Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 07/21/13


AREA FORECAST DISCUSSION
NWS TUCSON AZ
900 PM MST SAT JUL 20 2013 .SYNOPSIS...LOW PRESSURE OVER THE GULF OF CALIFORNIA WILL PROVIDE A MOIST EAST TO SOUTHEAST FLOW THIS WEEKEND. THIS FLOW WILL INCREASE CHANCES FOR SHOWERS AND THUNDERSTORMS WITH POTENTIALLY HEAVY RAINFALL. THEREAFTER...A MORE NORMAL CYCLE OF SCATTERED AFTERNOON AND EVENING THUNDERSTORMS WILL RETURN FOR MUCH OF NEXT WEEK. && .DISCUSSION...AFTER AN ACTIVE AND WET AFTERNOON...ACTIVITY ACROSS SOUTHEAST ARIZONA HAS DIMINISHED A BIT. HOWEVER...THE ATMOSPHERE IS STILL VERY MOIST AND WITH THE REMNANT OUTFLOW BOUNDARIES FLOATING AROUND...THERE IS STILL SOME POTENTIAL FOR ISOLATED CONVECTION THROUGH THE OVERNIGHT HOURS. IN FACT...DYING STORMS IN WESTERN NEW MEXICO PUSHED OUT A BOUNDARY THAT IS HEADING INTO THE GREENLEE/COCHISE COUNTY AREA AND MAY TRIGGER STORMS IN THE NEXT FEW HOURS. PLUS...WE STILL HAVE OUR UPPER LOW CHURNING TO THE SW...SO THE BEST LIFT WILL OCCUR OVER OUR WESTER ZONES. THE HRRR KEEPS US ON THE QUIET SIDE THROUGH THE REST OF THE EVENING AND THIS DOES MAKE SENSE GIVE THE POST STORM STABLE ATMOSPHERE IN PLACE. SO THE BIG QUESTION IS WHETHER OR NOR THE REMNANT BOUNDARIES CAN OVERCOME THE STABLE ATMOSPHERE TO PRODUCE CONVECTION. WITH ALL THAT IN MIND...I WILL INCREASE POPS TO THE CHANCE RANGE IN WESTERN PIMA AND KEEP THE CHANCE POPS ACROSS THE REST OF THE CWA. THERE IS STILL SOME POTENTIAL FOR HEAVY RAIN OVERNIGHT AND GIVEN THE WET GROUND IN PLACE...WE WILL NEED TO WATCH THE FLOOD THREAT. JJB && .AVIATION...SCATTERED TO NUMEROUS SHRA/TSRA WILL CONTINUE INTO THE EVENING...BECOMING MORE ISOLATED AFT 21/03Z. EXPECT MVFR CIGS AND VSBYS WITH BRIEF WIND GUSTS UP TO 40 KTS WITH THE STRONGER TSRA. CONDITIONS SCT-BKN060 SCT-BKN100 BKN250 THEN AFT 21/08Z SCT060 SCT-BKN100. SURFACE WIND DIURNAL IN DIRECTION AND GENERALLY LESS THAN 10 KTS THRU SUNDAY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. CERNIGLIA && .FIRE WEATHER...AN UPPER LOW OVER THE NORTHERN GULF OF CALIFORNIA WILL CONTINUE TO PUMP MOISTURE OVER SOUTHERN ARIZONA THROUGH SUNDAY AS IT SLOWLY MOVES WEST. THIS MOISTURE AND THE RESULTANT INSTABILITY WILL BRING ABOUT PLENTY OF CONVECTION THROUGH SUNDAY EVENING. THE STRONGER THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY DOWNPOURS DUE TO THE ABUNDANT MOISTURE AS WELL AS GUSTY AND ERRATIC WINDS. NORMAL DIURNAL WIND PATTERNS ARE EXPECTED OVER THE NEXT SEVERAL DAYS...HOWEVER THEY WILL BE DISRUPTED AT TIMES DUE TO STORM OUTFLOWS. THE SHOWERS AND THUNDERSTORMS WILL BECOME LESS NUMEROUS AND MORE LIMITED TO THE AFTERNOON AND EVENING HOURS MONDAY AND TUESDAY AS THE LOW MOVES FURTHER WEST AND THE AIR MASS BECOMES A BIT DRIER OVER THE REGION. ANOTHER EASTERLY WAVE WILL ENHANCE THE CONVECTION ACROSS SOUTHERN ARIZONA WEDNESDAY AND THURSDAY AS IT PASSES BY TO THE SOUTH. CERNIGLIA && .PREV DISCUSSION...THE UPPER LOW SPINNING OVER THE GULF OF CALIFORNIA WAS HELPING TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS EARLY THIS AFTERNOON. THE STEERING FLOW WAS TRACKING THIS ACTIVITY WESTWARD AT 15 MPH...WITH A FEW OF THE STRONGER THUNDERSTORMS PRODUCING RAINFALL AMOUNTS OF ONE-HALF OF INCH IN 15 TO 30 MINUTES. THAT SAID...THESE RAINFALL RATES CAN CAUSE MINOR FLOODING IN POOR DRAINAGE AREAS AND RAPID RUNOFF INTO NORMALLY DRY WASHES. THE STRONGEST STORMS COULD PRODUCE HIGH WINDS...BUT FLASH FLOODING WILL BE THE PRIMARY THREAT FROM THESE STORMS TODAY. THE UPPER LOW OVER THE GULF OF CALIFORNIA TODAY WILL TRACK THROUGH SOUTHERN CALIFORNIA AND WEAKEN SUNDAY INTO MONDAY. WILL SEE ANOTHER ACTIVE THUNDERSTORM DAY TOMORROW BEFORE DRIER AIR SPREADS IN BEHIND THE UPPER LOW ON MONDAY. THEREAFTER...HIGH PRESSURE ALOFT BECOMES CENTERED NEAR THE FOUR CORNERS REGION AROUND TUESDAY AND WEDNESDAY. OVERALL...THE PATTERN APPEARED FAVORABLE FOR DAILY THUNDERSTORM ACTIVITY THROUGH AT LEAST FRIDAY. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS PUEBLO CO
313 PM MDT FRI JUL 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 238 PM MDT FRI JUL 19 2013 AN UPR RIDGE WL REMAIN CENTERED OVR NV TONIGHT AND SATURDAY. A UPR DISTURBANCE WL CONTINUE MOVING SOUTH ACRS THE FORECAST AREA TONIGHT. THERE IS PLENTY OF MOISTURE OVER THE AREA AS WELL. ALL THE INGREDIENTS SEEM TO BE IN PLACE TO BRING WIDESPREAD PCPN OVR AND NR THE MTS...WITH SCT ACTIVITY OVR THE SERN PLAINS. THE STEERING FLOW WL REMAIN FAIRLY LIGHT...RESULTING AND SLOW MOVING STORMS AND THUS UNDER THE HEAVIER STORMS...LOCALLY HEAVY RAIN COULD FALL. THIS BECOMES A BIG CONCERN IF IT OCCURS OVR THE BURNS SCARS AS MUD AND ASH FLOWS COULD OCCUR. WL LEAVE THE FLASH FLOOD WATCH IN EFFECT FOR EL PASO AND TELLER COUNTIES. AS THE UPR DISTURBANCE MOVES SOUTHWARD OVR THE AREA...BOTH THE RAP13 AND NAM SHOW THE FOCUS OF PCPN SHIFTING SOUTHWARD THIS EVENING OVR THE SRN MTS AND SOUTH OF HIGHWAY 50. THE HRRR ALSO SHOWS WIDESPREAD PCPN AND CHANCES FOR RAIN OVR SRN AREAS...BUT ALSO INCREASES PCPN CHANCES OVR EL PASO...TELLER COUNTIES AND PUEBLO COUNTIES DURING THE EVENING HOURS. OVERNIGHT...PCPN CHANCES ARE EXPECTED TO DECREASE OR END FROM NORTH TO SOUTH...WITH SOME LIGHT PCPN POSSIBLY LINGERING THRU THE NIGHT OVR FAR SOUTHERN AREAS. IT LOOKS DRIER IN THE UPR LEVELS ON SATURDAY AS THE MSTR PLUME SHIFTS SOUTH OF THE AREA...BUT THERE WL STILL BE PLENTY OF LOW LEVEL MSTR TO WORK WITH FOR SCT TO LIKELY POPS OVR THE MTS AND PROBABLY ISOLD TO SCT POPS OVR THE SERN PLAINS. STORMS SHOULD BE FAIRLY SLOW MOVING AGAIN AND WE COULD SEE SOME LOCALIZED HEAVY RAIN. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 238 PM MDT FRI JUL 19 2013 UPPER LEVEL FLOW TURNS SLIGHTLY MORE NORTHWESTERLY SUNDAY...WHICH WILL TEND TO PUSH THE MOIST PLUME SOUTH OF THE STATE INTO NM AND AZ BY AFTERNOON. MODELS SHOW WEAK FRONTAL BOUNDARY DISSIPATING SOMEWHERE OVER THE ERN PLAINS OF CO...WITH DECREASING LOW LEVEL MOISTURE AS UPSLOPE WINDS WEAKEN. SUSPECT TSRA WILL STAY ISOLATED AND LIMITED TO MAINLY THE HIGHER TERRAIN SUN AFTERNOON AND EVENING...AND WILL END QUICKLY BY LATE EVENING WITH LITTLE IN THE WAY OF UPPER SUPPORT. MAX TEMPS SUN SHOULD CREEP UPWARD A DEGF OR TWO...THOUGH 700 MB TEMPS SUGGEST RATHER HOT MET GUIDANCE MAXES MAY BE JUST A TAD TOO WARM. SIMILAR SET-UP MON/TUE...AS WEAK SURFACE FRONT REFORMS OVER NORTHEAST COLORADO AND AIR MASS OVER SOUTHERN COLORADO CONTINUES TO DRY. AGAIN EXPECT ISOLATED MOUNTAIN CONVECTION BOTH DAYS...THOUGH COVERAGE AND RAINFALL AMOUNTS WILL BE RATHER SPARSE. 700 MB TEMPS CREEP UPWARD INTO THE 18C-20C RANGE...WHICH SHOULD PRODUCE A FEW 100F PLUS READINGS OVER THE EASTERN PLAINS BOTH DAYS. ON WED...FRONT DROPS SOUTH OVER THE PLAINS LEADING TO A RENEWED WESTWARD SURGE OF MOISTURE OVER THE EASTERN MOUNTAINS AND PLAINS BY AFTERNOON. GFS AND ECMWF ARE SIMILAR WITH SURFACE FEATURES...BUT ONLY GFS BREAKS OUT CONVECTION THU EVENING...WHILE ECMWF STAYS DRY. WILL LEAN TOWARD THE WETTER SOLUTION OF THE GFS FOR NOW...GIVEN THE DEEPER MOISTURE AND INSTABILITY BEHIND THE FRONT. FARTHER WEST...LOW GRADE MONSOON REDEVELOPS WED AS SLIGHTLY DEEPER MID LEVEL MOISTURE PUSHES BACK INTO THE STATE...LEADING TO BETTER TSRA COVERAGE THAN MON/TUE. PAST WED...MOISTURE LOOKS TO SLOSH BACK AND FORTH ACROSS THE EASTERN PLAINS...WITH PERHAPS A DECREASE IN PRECIP CHANCES THU AND AN INCREASE FRI. OVER THE MOUNTAINS...UPSWING IN CONVECTION LOOKS POSSIBLE FRI AS WELL...ESPECIALLY AS LAST FEW MODEL RUNS OF BOTH THE ECMWF AND GFS TRY TO BUILD THE UPPER RIDGE EASTWARD INTO TX...ALLOWING A RENEWED INFLUX OF MOISTURE FROM THE SOUTH. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 238 PM MDT FRI JUL 19 2013 THUNDERSTORMS WILL BE POSSIBLE THROUGH THIS EVENING AT KPUB...KCOS AND KALS...PROBABLY ENDING BY 06Z...ALTHOUGH COULD CONTINUE A BIT LATER AT KALS. HEAVY RAIN WILL BE POSSIBLE AT THE TAF SITES WHICH COULD BRIEFLY CAUSE MVFR/IFR CONDITIONS. OTHERWISE VFR CONDITIONS ARE EXPECTED. ON SATURDAY THE TAFS SITES COULD AGAIN SEE SOME SHOWERS AND THUNDERSTORMS...MAINLY AFTER 20Z. && .PUB WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR COZ081-082- 084-085. && $$ SHORT TERM...28 LONG TERM...PETERSEN AVIATION...28
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
309 PM MDT FRI JUL 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 308 PM MDT FRI JUL 19 2013 SHOWERS AND THUNDERSTORMS DEVELOPING FIRST OVER THE CENTRAL AND SOUTHERN MTNS THIS AFTERNOON ARE EXPECTED TO INCREASE IN COVERAGE AS THE DAY WEARS ON AND INSTABILITY CONTINUES BEING REALIZED. A BIT SLOWER START TODAY LIKELY THE RESULT OF MORE MORNING CLOUDINESS AS COMPARED TO THURSDAY. THE FLASH FLOOD WATCH REMAINS IN EFFECT FOR ALL BUT THE NORTHERN-MOST COUNTIES...WHERE A BIT DRIER AIR WAS WORKING IN. HOWEVER...THE HIGH-RESOLUTION HRRR MODEL AND THE NAM12 FOCUS PRECIPITATION MORE ON SE UT AND SW CO AND UP ACROSS GUNNISON COUNTY THROUGH LATE EVENING. THIS SEEMS REASONABLE AS SATELLITE IMAGES SHOW THE MONSOONAL MOISTURE PLUME AND ASSOCIATED DEFORMATION ZONE LAYING OVER AND BECOMING MORE EAST-WEST ORIENTED ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. SEE HYDROLOGY SECTION FOR ADDITIONAL INFO. DRIER AIR WILL CONTINUE TO CIRCULATE AROUND HIGH PRESSURE CENTERED OVER NEVADA ON SATURDAY. THE 12Z MODELS INDICATE PRECIPITABLE WATER DROPS BELOW 0.50 INCH ACROSS OUR NORTH AND CENTRAL AREAS ON SATURDAY...COMPARED TO 0.75 TO 1.30 VALUES FOR TODAY. THIS WILL CONFINE SCATTERED SHOWERS AND THUNDERSTORMS TO SOUTH OF INTERSTATE 70 SATURDAY AFTERNOON. THE BEST COVERAGE WILL BE OVER THE SAN JUAN MTNS WHERE PRECIPITABLE WATER VALUES OF OF 0.70 OR 0.80 INCH WILL PERSIST. CONVECTION SHOULD DIE OUT BEFORE MIDNIGHT WITH THE LOSS OF HEATING. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 308 PM MDT FRI JUL 19 2013 WARMER AND DRIER THROUGH TUESDAY THEN A RETURN OF MONSOONAL MOISTURE BEGINNING WEDNESDAY. GOOD MODEL AGREEMENT CONTINUES. INTO EARLY NEXT WEEK THE UPPER HIGH REMAINS CENTERED OVER THE GREAT BASIN AND NORTHERN CALIFORNIA...WITH AN INVERTED TROUGH IN NORTHERN BAJA. A N-NW FLOW KEEPS DRIER AIR ACROSS DOWN TO NEAR THE FOUR CORNERS ON SUNDAY. MODELED PRECIPITABLE WATER VALUES ARE AT OR LESS THEN 0.5 INCH FOR MUCH OF THE CWA WITH A SHARP INCREASED GRADIENT ALONG THE NM/AZ BORDER. SO SCATTERED SHOWERS AND STORMS WILL FAVOR THE FAR SOUTH AND ALONG THE SOUTHERN PORTION OF THE CONTINENTAL DIVIDE. THIS DRIER AIR REMAINS IN PLACE THROUGH TUESDAY. DIURNAL TEMPERATURE SPREAD WILL INCREASE IN THE DRIER AIR MASS WITH THE LOWER VALLEYS OF UTAH AND FAR WESTERN COLORADO THREATENING TRIPLE DIGIT AFTERNOONS AGAIN. DEWPOINTS IN THE 20-30S ALONG AND NORTH OF I-70 WILL HELP EVAPORATIVE COOLERS TO WORK MORE EFFICIENTLY. WEDNESDAY...THERE IS GOOD MODEL AGREEMENT THAT THE UPPER HIGH BEGINS TO SHIFT TO SOUTH CENTRAL COLORADO...THEN ONTO THE SOUTHERN PLAINS ON THURSDAY AND FRIDAY. MEANWHILE THE NORTHERN BAJA LOW BEGINS TO LIFT NE INTO THE GREAT BASIN BRINGING SUBTROPICAL MOISTURE WITH IT. THIS DEEPER MOISTURE AND INCREASED THUNDERSTORM POTENTIAL IS CURRENTLY TIMED TO SPREAD INTO EASTERN UTAH WEDNESDAY IN THE FASTER EC THEN WESTERN COLORADO ON THURSDAY AND FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 308 PM MDT FRI JUL 19 2013 SIMILAR TO YESTERDAY...SCATTERED SHOWERS AND THUNDERSTORMS MAINLY ACROSS THE CENTRAL AND SOUTH LATE TONIGHT WILL BECOME MORE NUMEROUS BY 00Z BEFORE DECREASING IN COVERAGE BY 06Z. HEAVY RAIN FROM THE STRONGER STORMS WILL CREATE PERIODS OF MVFR OR EVEN IFR VISIBILITY AT TIMES...WITH MOUNTAIN OBSCURATIONS. KVEL IS THE TAF SITE LEAST LIKELY TO BE AFFECTED. DRIER AIR WORKS IN FROM THE NW LATE TONIGHT AND SATURDAY CONFINING CONVECTIVE ACTIVITY MAINLY SOUTH OF I-70 AFTER 18Z SATURDAY. VFR SHOULD BE THE PREVAILING FLIGHT CONDITION AT ALL TAF SITES ON SATURDAY. && .HYDROLOGY... ISSUED AT 308 PM MDT FRI JUL 19 2013 THE FLASH FLOOD WATCH CONTINUES FOR MUCH OF THE FORECAST AREA. WILL BE MONITORING STORMS CLOSELY ONCE THEY DEVELOP FOR THE POTENTIAL OF EXCESSIVE RAINFALL/RUNOFF. SOME AREAS THAT MAY BE MORE PRONE TO RUNOFF PROBLEMS WILL BE THOSE LOCATIONS THAT HAVE ALREADY RECEIVED HEAVIER RAIN. BURN SCARS WILL LITTLE OR NO REGROWTH WILL BE ESPECIALLY SUSCEPTIBLE TO ASH AND DEBRIS/MUD FLOW IN HEAVY RAIN. THE THREAT OF HEAVY RAIN AND FLASH FLOODING DECREASES THIS WEEKEND. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR COZ001>003- 006>014-017>023. UT...FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR UTZ022-025- 027>029. && $$ SHORT TERM...JAD LONG TERM...JOE AVIATION...JAD HYDROLOGY...JAD
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1008 AM MDT FRI JUL 19 2013 .UPDATE...ONLY MINOR ADJUSTMENTS AT THIS TIME. SHOWERS AND TSTMS OVER THE NORTHEAST PLAINS THIS MORNING WILL PERSIST INTO THE EARLY AFTERNOON....WITH SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE MOUNTAINS AND FOOTHILLS AROUND 18Z. HRRR RUNS OFFERING DIFFERING SOLUTIONS REGARDING THE COVERAGE AND INTENSITY OF THE STORMS OVER THE FOOTHILLS THIS AFTERNOON SO WILL NOT CHANGE ANY ANYTHING REGARDING THE FLASH FLOOD WATCH AT THIS TIME. SINCE THE BURN AREAS ALREADY GOT A GOOD DOSE OF RAINFALL YESTERDAY...THAT REASON ALONE WILL JUSTIFY THE WATCH. SOME SOLUTIONS SUPPORT THE FLASH FLOOD WATCH WHILE OTHERS ARE DRIER. HARD TO SAY AT THIS POINT...SO WILL JUST HAVE TO MONITOR HOW THINGS DEVELOP. && .AVIATION...SFC WINDS BECOMING NNELY AT THIS TIME SO TREND IN THE WIND FCST STILL LOOKS ON TRACK. NO CHANGE REGARDING THE TIMING OF TSTMS THIS AFTN AND EVENING AT THIS TIME. IF HEAVY RAIN DEVELOPS WITH TSTMS THEN BRIEF MVFR CIGS/VSBYS WILL BE POSSIBLE. && .PREV DISCUSSION... /ISSUED 317 AM MDT FRI JUL 19 2013/ SHORT TERM...WATER VAPOR LOOP SHOWS UPPER LEVEL MOISTURE PLUME SHIFTING VERY SLOWLY SOUTHWARD ACROSS THE FORECAST AREA EARLY THIS MORNING. MEANWHILE...LAST NIGHTS PERSISTENT CONVECTION HAS LEFT BEHIND A MESOSCALE CONVECTIVE VORTEX...OR MCV...OVER NORTHERN WELD COUNTY... CREEPING EASTWARD. MCVS ARE QUITE RARE AROUND HERE...BUT CAN SERVE TO SPARK CONVECTION ON THE DOWNSHEAR...OR SOUTH/SOUTHEAST SIDE IN THIS CASE. HARD TO SAY EXACTLY WHERE THIS FEATURE WILL BE BY THE TIME WE REACH CONVECTIVE TEMPS...BUT SHOULD BE SOMEWHERE IN NORTHEAST COLORADO. OTHERWISE...AS THE WATER VAPOR PLUME CONTINUES TO SHIFT SOUTHWARD THIS WILL BRING A BETTER CHANCE OF STORMS TO THE DENVER METRO AREA/I-70 CORRIDOR/POINTS SOUTHWARD THIS AFTERNOON. WE COULD SEE A FEW SHOWERS LINGER THIS MORNING AS WELL...BUT CONVECTIVE STORMS WILL LIKELY INITIATE IN/NEAR THE FRONT RANGE AND DOWNSHEAR SIDE OF THE MCV BY LATE MORNING/NOON HOUR AS CONVECTIVE TEMPS ARE REACHED. POTENTIAL FOR HEAVY RAIN WILL BE THERE ESPECIALLY WITH THE HIGHEST PRECIPITABLE WATER PLUME SHIFTING SOUTHWARD TODAY. WHILE THE NORTHERN PORTIONS COULD SEE SOME DRYING AND EVEN SUBSIDENCE ON THE UPSHEAR SIDE OF THE MCV...ENOUGH FACTORS MENTIONED IN HYDROLOGY SECTION BELOW TO WARRANT A FLASH FLOOD WATCH FOR THE FOOTHILLS WITH MAIN THREAT ONCE AGAIN FOR THE BURN SCARS. COULD SEE RAINFALL RATES OF 1-1.5 INCHES IN 45 MINUTES FROM THE STRONGEST STORMS. EXPECT THINGS TO WIND DOWN FAIRLY QUICKLY THIS EVENING WITH SOME DRYING NOTED MOVING IN FROM THE NORTH/NORTHWEST. LONG TERM...A SLIGHT INCREASE IN NORTHWESTERLY FLOW ALOFT IS EXPECTED SATURDAY ALONG WITH A THETA E RIDGE ACROSS EASTERN COLORADO. CAPE VALUES OF BETWEEN 1000-1500 J/KG WILL BE FOUND OVER FAR NORTHEASTERN COLORADO. THIS WILL ALL COMBINE TO BRING A SLIGHT CHANCE OF SEVERE STRENGTH STORMS OVER THIS AREA. ELSEWHERE...ENOUGH MOISTURE WILL BE AROUND TO ALLOW FOR ISOLATED TO SCATTERED THUNDERSTORM ACTIVITY. MOISTURE WILL BE ON THE DECREASE OVER TODAY HOWEVER...SO FLOODING CONCERNS ARE A LOT LESS. TEMPERATURES WILL BE WARMING A FEW DEGREES AS THE UPPER HIGH OVER NEVADA CIRCULATES WARMER AIR AROUND INTO THE STATE. SUNDAY THROUGH THURSDAY WILL FEATURE THE UPPER HIGH OVER NEVADA TO BEGIN TO MIGRATE BACK EAST. THIS WILL BRING AN OVERALL WARMING PATTERN. SUNDAY AND MONDAY WILL BE MOSTLY DRY EXCEPT A FEW POSSIBLE STORMS OVER THE HIGH COUNTRY. THEN A WEAK SHORTWAVE COMING DOWN OUT OF THE NORTHERN ROCKIES MAY PUSH A COOL FRONT DOWN THE LEE SIDE OF THE ROCKIES TO BRING A BRIEF RESPITE FROM THE WARM AND DRY PATTERN. HOWEVER...MODELS DISAGREEING IF THIS FRONT WILL MAKE IT INTO CO...FOR NOW WILL TREND THE FORECAST TO BRING IT IN WITH COOLER TEMPS AND SLIGHT CHANCE OF STORMS FOR THE PLAINS ON TUESDAY AND AREA WIDE WEDNESDAY. FOR THURSDAY...IT LOOKS LIKE THE UPPER LOW WHICH RETROGRADED FROM WEST VIRGINIA ALL THE WAY TO ITS CURRENT POSITION OVER SONORA, MEXICO WILL CONTINUE ITS PATH WEST...THEN GET PULLED NORTH AROUND THE UPPER HIGH. THEN ITS PROGGED TO MOVE EAST ONSHORE AND BRING MORE MOISTURE OUR WAY FOR THURSDAY. HAVE POPS ACROSS THE FORECAST AREA TO ACCOUNT FOR THIS. AVIATION...STORM THREAT IS A LITTLE HIGHER TODAY GIVEN THE ABOVE MENTIONED FACTORS SO WILL LIKELY NEED TEMPO TSRA AND GUSTY VRB WINDS TO 35 KTS FOR A FEW HOURS THIS AFTERNOON. MAIN THREAT SHOULD BE 20Z-01Z WITH STORMS SHIFTING SOUTH OF THE FRONT RANGE AIRPORTS 01Z-04Z. BRIEF IFR/MVFR CONDITIONS POSSIBLE WITH THE STRONGEST STORMS. OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT. HYDROLOGY...LOWER LIFTING CONDENSATION LEVELS AND RESULTANT DEEPER WARM CLOUD DEPTH NEAR 1500 METERS MEANS MORE EFFICIENT RAINERS POSSIBLE TODAY. AS A RESULT...HAVE OPTED FOR A FLASH FLOOD WATCH FOR THE FRONT RANGE FOOTHILLS WITH MAIN THREAT OF FLASH FLOODING ONCE AGAIN FOR THE BURN SCARS. COULD SEE RAINFALL RATES OF 1-1.5 INCHES IN 45 MINUTES FROM THE STRONGEST STORMS. EXPECT THINGS TO WIND DOWN BY 7-8 PM THIS EVENING WITH SOME DRYING NOTED MOVING IN FROM THE NORTH/NORTHWEST. THERE IS A CHANCE OF SUBSIDENCE AND DRYING MOVING IN A LITTLE EARLIER FOR THE NORTHERN FRONT RANGE BURN SCARS INCLUDING HIGH PARK AND FOURMILE...BUT STILL ENOUGH THREAT ESPECIALLY CONSIDERING RAINFALL YESTERDAY AND ANTECEDENT CONDITIONS TO WARRANT A WATCH AT THIS TIME. && .BOU WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 8 PM MDT THIS EVENING FOR COZ035-036. && $$ SHORT TERM...COOPER LONG TERM....D-L AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1121 PM MDT THU JUL 18 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 323 PM MDT THU JUL 18 2013 MAIN CONCERN IS THE POTENTIAL FOR HEAVY RAIN MAINLY ON FRIDAY. THIS AFTERNOON...WATER VAPOR IMAGERY IS SHOWING THE MSTR PLUME MAINLY OVR FAR WRN CO...BUT PLENTY OF SHOWERS AND TSTMS HAVE POPPED UP ALONG THE CONTDVD. SOME OF THE STORMS HAVE BRIEFLY BEEN STRONG...LIKELY PRODUCING SMALL HAIL AND HEAVY RAIN. OVR THE ERN MTS...SO FAR THERE HAVE ONLY BEEN SOME ISOLD STORMS. STEERING FLOW ALOFT IS EASTERLY AND THUS THE STORMS ARE MOVING TOWARD THE WEST. NOT EXPECTING CONVECTION TO DEVELOP OVR THE SERN PLAINS...BUT LOCATIONS ALONG THE I-25 CORRIDOR WILL PROBABLY SEE SOME ACTIVITY THIS EVENING. THE NAM HAS BEEN CONSISTENT IS SHOWING SCT PCPN DEVELOPING THIS EVENING OVR EL PASO AND PUEBLO COUNTIES...WHILE THE HRRR AND RAP13 SHOW ONLY SOME ISOLD ACTIVITY. THERE IS THE POTENTIAL THIS EVENING FOR STRONGER STORMS TO PRODUCE HEAVY RAIN...SO WL HAVE TO KEEP AN EYE ON ANYTHING THE DEVELOPS OR MOVES OVR THE ANY OF THE BURN SCARS. AFTER MIDNIGHT THERE COULD BE JUST SOME ISOLD SHOWERS/TSTMS LINGERING THRU THE NIGHT IN A FEW AREAS...BUT THE CENTRAL MTS...TELLER...EL PASO...FREMONT AND PUEBLO COUNTIES WL HAVE THE BEST CHANCES OF SEEING SOME LINGERING CONVECTION. MODELS SHOWING A SFC LOW DEVELOPING OVR THE SE CORNER OF CO...CAUSING THE SFC WINDS TO BE NORTHEASTERLY UPSLOPE...AND LOW LEVEL MSTR WL BE IN PLACE AS WELL. MODELS ARE STILL CONSISTENT ON DEVELOPING PCPN IN THE MORNING HOURS OF FRI ALONG THE I-25 CORRIDOR AND THE HYR TRRN...WITH SOME ACTIVITY OVR THE FAR SERN PLAINS BY LATE AFTERNOON. PRECIPITABLE WATER VALUES ARE NOT FORECAST TO BE AS HIGH FOR FRI AS WHAT THEY WERE SHOWING THE LAST COUPLE DAYS FOR FRI...AND NOT AS HIGH AS THEY WERE WHEN THERE WAS FLASH FLOODING LAST WEEKEND. HOWEVER...THERE WILL STILL BE THE POTENTIAL FOR LOCALLY HEAVY RAIN WITH STRONGER STORMS ON FRI AND THUS FLASH FLOODING IS STILL A CONCERN...ESPECIALLY OVR THE BURN SCARS. THE FLOW ALOFT ON FRI WL BE NORTH TO NORTHEAST AND THUS STORMS ARE EXPECTED TO MOVE TOWARD THE SOUTH OR SOUTHWEST. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 323 PM MDT THU JUL 18 2013 LONGER TERM METEOROLOGICAL CHALLENGES INCLUDES POPS AND TEMPERATURES. FRIDAY NIGHT INTO SATURDAY SATURDAY SHOULD EXPERIENCE CONTINUED ELEVATED POPS(ESPECIALLY OVER SOUTHERN AND WESTERN SECTIONS) AS WELL AS NEAR SEASONAL TEMPERATURES BEFORE SOMEWHAT WARMER AND DRIER CONDITIONS DEVELOP OVER THE FORECAST DISTRICT FROM LATER IN THE WEEKEND INTO NEXT WEEK. LATEST LONGER TERM COMPUTER SIMULATIONS AND FORECAST SOUNDINGS INDICATE THAT ROUNDS OF BASICALLY SCATTERED SHOWERS AND THUNDERSTORMS CAPABLE OF PRODUCING LOCALLY HEAVY RAIN AND BURN SCAR ISSUES(ESPECIALLY OVER WESTERN AND SOUTHERN SECTIONS) WILL BE POSSIBLE FROM FRIDAY NIGHT INTO SATURDAY NIGHT IN WAKE OF NORTHERLY SURGE ALLOWING INCREASED ATMOSPHERIC MOISTURE/PRECIPITABLE WATER VALUES. WFO PUEBLO WILL CONTINUE TO MONITOR CLOSELY. THEN...A DEVELOPING RIDGE OF HIGH PRESSURE INITIALLY CENTERED OVER WESTERN NEVADA AT 00Z MONDAY IS PROJECTED TO BECOME CENTERED OVER SOUTHERN COLORADO BY 00Z THURSDAY BEFORE SHIFTING SOUTHEAST INTO THE TEXAS PANHANDLE BY 00Z FRIDAY. AS THIS OCCURS...ANTICIPATE THAT POPS WILL BECOME MORE ISOLATED FROM SUNDAY INTO NEXT WEEK IN COMBINATION WITH WARMER TEMPERATURES. SPEAKING OF TEMPERATURES...NEAR SEASONAL MAXIMUM TEMPERATURES ARE ANTICIPATED SATURDAY WITH ABOVE SEASONAL MAXIMUM TEMPERATURES THEN PROJECTED OVER THE FORECAST DISTRICT FROM SUNDAY INTO THURSDAY. MAXIMUM TEMPERATURES OVER PORTIONS OF THE SOUTHEASTERN PLAINS MAY CHALLENGE THE CENTURY MARK AT TIMES...ESPECIALLY FROM MONDAY INTO THURSDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1120 MDT THU JUL 18 2013 VFR CONDITIONS EXPECTED AT TAF SITES THROUGH THE REST OF TONIGHT WITH ISOLATED SHRA/TSRA CONTINUING TO DIMINISH ACROSS THE HIGHER TERRAIN. ALS PICKED UP SOME RAIN THIS EVENING...THOUGH THERE LOOKS TO BE ENOUGH MID AND HIGH LEVEL CLOUDS TO KEEP FOG FROM FORMING OVERNIGHT. SHOWERS AND THUNDERSTORMS WILL BE ON THE UPSWING EARLY FRIDAY MORNING AS A WEAK DISTURBANCE EMBEDDED WITHIN THE MONSOON MOISTURE PLUME MOVES SOUTH ACROSS THE STATE. COULD SEE SHOWERS AND THUNDERSTORMS AFFECTING COS AND PUB BETWEEN 16Z-21Z AND THROUGH THE AFTERNOON FOR ALS. MVFR AND BRIEF IFR CONDITIONS WILL BE POSSIBLE WITH LOCALLY HEAVY RAINFALL. HAVE KEPT VCTS IN THROUGH THE LATE AFTERNOON WITH CONVECTION LIKELY WINDING DOWN THROUGH THE EVENING. $$ .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ AVIATION...MW
AREA FORECAST DISCUSSION
NWS MIAMI FL
1027 PM EDT SAT JUL 20 2013 .UPDATE... ONLY A FEW CHANGES WERE NECESSARY THIS EVENING BASED ON THE LATEST TRENDS AND OBSERVATIONS AROUND THE LOCAL AREA. OTHERWISE...THE PREVIOUS FORECAST PACKAGE REMAINS ON TRACK. THE AFTERNOON/EARLY EVENING CONVECTION THAT MOSTLY IMPACTED THE INTERIOR AREAS AROUND THE LAKE REGION HAS DIMINISHED. THE LATEST HRRR RUN HAS LINED UP WELL WITH THE CURRENT CONDITIONS AND GENERALLY INDICATES A QUIET NIGHT WITH THE EXCEPTION OF SOME SHOWERS DEVELOPING OVER THE ATLANTIC WATERS THROUGH THE OVERNIGHT HOURS. FOR SUNDAY...DRIER AIR WILL BEGIN TO SPREAD NORTH INTO THE AREA AS THE RIDGE BEGINS TO BUILD OVERHEAD AND THE WEAK TROUGH LIFTS AWAY FROM THE AREA. HOWEVER...LINGERING MOISTURE OVER THE NORTHERN HALF OF THE CWA...OR AROUND THE LAKE REGION...WITH PWAT VALUES AROUND 2" COMBINED WITH SW LOW-LEVEL FLOW WILL BE ENOUGH TO THE KEEP THE AFTERNOON/EVENING SHOWERS/TSTMS IN THE FORECAST. && .PREV DISCUSSION... /ISSUED 723 PM EDT SAT JUL 20 2013/ AVIATION... OUTFLOW FROM INTERIOR CONVECTION IS MEETING DECAYING SEA BREEZE BOUNDARY OVER THE EASTERN METROPOLITAN AREAS THIS EVENING...THUS VCSH/VCTS IN TAFS BROWARD AND PALM BEACH COUNTIES TERMINALS. OUTFLOW BOUNDARY SHOULD BRING A BRIEF PERIOD OF WNW WINDS TO MIAMI-DADE TERMINALS...SO HAVE INCLUDED A TEMPO GROUP NOTING THE WIND SHIFT. OTHERWISE...LIGHT ESE WINDS WILL PREVAIL...AT SPEEDS OF AROUND 5 KTS TONIGHT AND 10 KTS ON SUNDAY. HAVE REMOVED VCSH BEYOND MIDNIGHT...AS POPS OVER THE TERMINALS ARE BELOW 30 PERCENT THROUGH SUNDAY. PREV DISCUSSION... /ISSUED 213 PM EDT SAT JUL 20 2013/ SHORT TERM (TONIGHT-MONDAY NIGHT)... A STRONG MID LEVEL RIDGE OVER THE MID ATLANTIC STRETCHES WEST TO ACROSS CENTRAL/SOUTH FLORIDA WITH MID LATITUDE TROUGHS MOVING ACROSS THE NORTHERN TIER OF STATES AND CANADA. A TROPICAL WAVE IS CURRENTLY MOVING THROUGH THE WESTERN CARIBBEAN SOUTHWEST OF JAMAICA AND THE NORTHERN EXTENT OF THIS WAVE IS LOCATED FROM THE EASTERN FLORIDA STRAITS AND INTO THE BAHAMAS. THIS HAS INCREASED CONVECTIVE ACTIVITY IN THAT REGION WITH HIGHER PWAT VALUES MOVING INTO SOUTH FLORIDA WHICH IN TURN IS HELPING TO ENHANCE CONVECTION. THE 12Z MFL SOUNDING WAS QUITE IMPRESSIVE AS REGARDS TO THE AVAILABLE CAPE BUT SO FAR THE STORMS HAVE BEEN SOMEWHAT SUPPRESSED DUE TO THE WEAK MID LEVEL LAPSE RATES ASSOCIATED WITH THE RIDGE AXIS. THE LOW LEVELS WERE VERY UNSTABLE HOWEVER AND THIS AIDED IN AN EARLY START TO THE CONVECTION PROCESS WITH STORM MOTION TO THE NORTHWEST DUE TO THE LOW LEVEL SOUTHEAST FLOW. THE FLOW BECOMES VERY WEAK TO LIGHT SOUTHWEST IN THE MID LEVELS IN RESPONSE TO THE RIDGE SO AS THE STORMS CONTINUE TO GROW, THE INTERIOR COULD GET QUITE ACTIVE LATER THIS AFTERNOON AS THE STORM MOTION BECOMES LESS THAN 5 MPH. THE WAVE WILL CONTINUE TO MOVE WEST OF THE AREA ON SUNDAY BUT AS MOISTURE CONTINUES TO LINGER ACROSS THE REGION WITH A WEAK SURFACE TROUGH BOUNDARY REMAINING IN PLACE, SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED AGAIN BY LATE SUNDAY MORNING INTO THE AFTERNOON. DUE TO THE WAVE BEING FARTHER TO THE WEST, THE LOW LEVEL SOUTHEAST FLOW WILL BECOME SHALLOWER SO STORM MOTION WILL GO EVEN LIGHTER AND SEA BREEZE BOUNDARIES WILL LIKELY BE THE DOMINANT FOCUSING MECHANISM. AT THE SAME TIME, A SURFACE RIDGE WILL BUILD BACK ACROSS SOUTH FLORIDA BY SUNDAY AFTERNOON THROUGH MONDAY AND THIS COULD SUPPRESS CONVECTIVE ACTIVITY EVEN FURTHER WITH SEA BREEZE BOUNDARIES AGAIN BEING THE MAIN FOCUS FOR MONDAY AFTERNOON. LONG TERM (TUESDAY-SATURDAY)... THIS SAME TREND WILL LIKELY CONTINUE THROUGH THE MIDDLE OF THE WEEK AS A DEEP LAYER RIDGE BECOMES FIRMLY ESTABLISHED AND FORECAST SOUNDINGS SHOW STORM MOTION 2 MPH OR LESS. A STRONG MID LEVEL TROUGH WILL BEGIN TO DEEPEN INTO THE EASTERN STATES BY THURSDAY INTO THE END OF THE WEEK AND INTO THE FIRST PART OF NEXT WEEKEND FOR A SLOW RETURN TO STORM MOTION STEERING STORMS BACK TOWARDS THE EAST COAST. FORECAST SOUNDINGS HOWEVER ARE NOT SHOWING A STRONG MOTION SO THE ENTIRE WEEK LOOKS AS IF VERY SLOW STORM MOTION WILL CONTINUE A THREAT FOR LOCALLY HEAVY RAINS WHERE EVER THE CONVECTION CAN SET UP. MARINE... GENERAL EAST TO SOUTHEAST WIND IS EXPECTED THROUGH TUESDAY AT SPEEDS OF LESS THAN 15 KNOTS OUTSIDE OF SCATTERED SHOWERS/THUNDERSTORMS. THE WIND WILL BEGIN TO VEER TO A SOUTH OR SOUTHWEST DIRECTION LATER IN THE WEEK AS THE SURFACE RIDGE SHIFTS TO THE SOUTH. FIRE WEATHER... NO PROBLEMS WITH PLENTY OF TROPICAL MOISTURE IN PLACE. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 76 89 76 88 / 20 20 20 30 FORT LAUDERDALE 78 89 79 89 / 20 20 20 30 MIAMI 77 90 77 88 / 20 20 20 20 NAPLES 76 91 75 89 / 10 20 10 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...85/AG AVIATION/RADAR...23/SK
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
402 AM EDT Fri Jul 19 2013 .NEAR TERM [Today and Tonight]... As has been advertised for the past couple days, we should be seeing a deep plume of tropical moisture arrive this morning. GOES blended precipitable water product shows the highest values lurking just offshore in the northeast Gulf of Mexico - on the order of 2.2 to 2.4 inches. This is actually not entirely unreasonable, as the 00z TBW sounding last evening sampled a 2.36" PWAT. The HRRR, other convection-allowing models (CAM), and even the global models show our PWATs increasing into this range later today. Forecast soundings also show a very deep warm cloud layer and weak flow in the mid-upper levels. Such environments can support very efficient rain production due to warm-rain processes, as well as backbuilding and quasi-stationary heavy rain bands. The global models are not really projecting much QPF over the next 24 hours, and our current grids only call for about 1-2" of rain through Saturday evening. However, CAM guidance and the HRRR do indicate localized maxima as high as 6-8" through tonight. Given that the environment can support very heavy rainfall, and the QPF signatures on the CAM guidance, we have issued a Hydrologic Outlook for all of our Florida zones. A Flash Flood Watch may become necessary depending on how things evolve during the daytime hours. For the forecast: PoPs were nudged up slightly again and "heavy rainfall" wording was inserted near the Florida Big Bend where models agree the best chances for heavy rain exist. Highs were kept similar to the inherited forecast and the HRRR - with low 80s near the Big Bend coast, to upper 80s in the northern third of our area. PoPs were kept above MOS overnight with warm temperatures as we may not see the usual diurnal cycle given the tropical air mass. In fact, our local WRF-ARW shows a band of heavy rain persisting through much of the night in parts of our Florida zones. && .SHORT TERM [Saturday Through Sunday]... It appears as though yet another wet and unsettled weekend is in store for the Tri-State area once again, as the persistent Synoptic scale pattern which keeps advecting deep layer tropical moisture into the region from the Gulf of Mexico (shown well on the blended TPW satellite product) will continue for much of the period. As mentioned above, if this level of moisture (with PWATS again over 2") is productive enough to generate heavy rainfall, Flooding could once again become a primary concern for parts of the CWA (as some areas in the eastern FL panhandle have recently received between 15 to 20" of rain! On Sunday, there is "some" hope that both Sfc and Upper level ridging will push far enough northward to at least bring PoPs back closer to climo, before the seemingly never ending troughing becomes re-established across the SE U.S by early mid week. Even after 19 years of forecasting at WFO TAE (where the Sea Breeze is typically the primary inducer of convection), the last 2 summers have been quite the aberration in my opinion. Therefore, it remains to be seen if a somewhat more "typical" summertime pattern can become established across the region before another summer has gone by the wayside. && .LONG TERM [Sunday Night through Wednesday]... Deep layer ridging will dominate the first part of the extended range forecast, with typical sea breeze patterns and rain chances through Monday. Thereafter, a trough will nose into the Southeast, nudging the mid/upper layer ridge out over our Gulf waters. Additionally, some form of surface reflection will slip into the Tri-State region and assist in the development of more widespread shower and thunderstorm development through the remainder of the period. && .AVIATION [through 12 UTC Saturday]... VFR conditions currently prevail at the TAF sites, and that is the way that most of the available guidance portrays the next 24 hours. However, with a very moist, tropical air mass moving into the area and fairly widespread rain expected - that may be a little too optimistic. We did insert some periods of MVFR this afternoon at all of the terminals with +RA possible. This may not be reduced enough, but confidence on location and timing of the heaviest rain was low. Therefore, pilots and flight planners can expect increasing MVFR over the region during the day, with IFR possible in and near the heavier rain showers and storms. && .MARINE... Light to moderate southerly winds will continue to impact the coastal waters, through Saturday, as an area of low pressure gradually exits the region. By Sunday, and the remainder of the period, high pressure at the surface should dominate, keeping winds and seas on the light side, with possible enhancements nearshore with the Sea Breeze, but this may not occur if conditions become and remain too disturbed aloft. && .FIRE WEATHER... Red flag conditions are not expected for the next several days. && .HYDROLOGY... A plume of deep tropical moisture is shifting toward the northeast gulf coast early this morning, and will overspread the interstate 10 corridor in Florida by midday. within this plume of tropical moisture, bands of heavy rain or thunderstorms are expected to develop and increase in coverage through the day. in environments such as this, heavier showers and thunderstorms can produce a considerable amount of rainfall in a short period of time. Average rainfall totals through Saturday evening across the Florida panhandle and big bend should be on the order of 1 to 2 inches. That amount of rainfall would generally be insufficient to produce much flooding across the area. However, localized rain totals could be quite a bit higher where heavier rain bands or thunderstorms can persist for more than an hour. Isolated totals in excess of 4 inches, perhaps as high as 6 to 8 inches, cannot be ruled out. Rainfall such as that could contribute to localized flooding, particularly in urban and low lying areas, and on rivers that are already experiencing high flows such as the St. Marks Aucilla rivers. A Flash Flood Watch could become necessary later today if model guidance becomes more supportive of localized very heavy rain amounts. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 83 74 88 73 92 / 70 50 60 30 40 Panama City 84 77 86 76 88 / 60 50 60 30 40 Dothan 88 74 88 72 89 / 50 40 60 30 50 Albany 89 73 88 73 90 / 50 40 60 30 50 Valdosta 85 73 90 74 92 / 70 50 60 30 50 Cross City 83 74 87 72 89 / 70 60 60 30 40 Apalachicola 82 77 86 77 86 / 70 60 60 30 40 && .TAE WATCHES/WARNINGS/ADVISORIES, FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Lamers SHORT TERM...Gould LONG TERM...Harrigan/Navarro AVIATION...Lamers MARINE...Gould FIRE WEATHER...Lamers HYDROLOGY...Lamers
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
334 PM EDT FRI JUL 19 2013 .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... CURRENT SATELLITE LOOP SHOWS CU FIELD CONTINUING TO DEVELOP ACROSS THE REGION THIS AFTERNOON. SCATTERED SHOWERS ACROSS NORTH AND SOUTH GA HAVE DEVELOPED OVER THE LAST FEW HOURS AND SHOULD CONTINUE THROUGH TONIGHT. THE MODELS ARE IN GOOD AGREEMENT IN THE SHORT TERM WITH THE GFS AND ECMWF SHOWING A NICE SLUG OF TROPICAL MOISTURE MOVING NORTHWARD OUT OF THE GULF TONIGHT. THIS MOISTURE IS EXPECTED TO MOVE SLOWLY NORTHWARD AND SHOULD BE ACROSS OUR AREA THOUGH THE WEEKEND. THE MAIN UPPER LEVEL LOW OVER THE GULF WILL FINALLY OPEN INTO A SHORT WAVE TROUGH BY SATURDAY AFTERNOON PUTTING GA IN GOOD SOUTHWEST FLOW. THIS WILL ALSO HELP TO ENHANCE THE SHRA/TSRA PROBABILITY ACROSS THE STATE. THIS INCREASED MOISTURE IS NOT EXPECTED TO BRING RAIN ACROSS THE AREA FOR WEEKS ON END LIKE WE EXPERIENCED IN MID JUNE THROUGH THE BEGINNING OF JULY. THE PATTERN WE ARE IN IS A MORE SUMMER LIKE PATTERN WITH DIURNALLY DRIVEN INSTABILITY AND CONVECTION SO ANYTHING THAT DOES DEVELOP THIS AFTERNOON AND SATURDAY AFTERNOON SHOULD DIMINISH AFTER SUNSET. 01 .LONG TERM /SUNDAY THROUGH FRIDAY/... MODELS ARE IN GOOD AGREEMENT WITH PEGGING BETTER PRECIP ACROSS NORTH GEORGIA ON SUNDAY SO WENT AHEAD AND INTRODUCED LIKELY TO THAT AREA. OTHERWISE ONLY MINOR TWEAKS TO THE EXTENDED AND THE PREVIOUS DISCUSSION FOLLOWS. 11 LONG TERM /SATURDAY THROUGH THURSDAY/... /ISSUED AT 349 AM EDT FRI JUL 19 2013/ MEDIUM RANGE MODELS START OUT QUITE SIMILAR TO BEGIN THE EXTENDED FORECAST PERIOD WITH A BROAD WEAKNESS IN THE UPPER FLOW OVER THE REGION THROUGH THE WEEKEND AS WEAK UPPER TROUGHING TAKES SHAPE ACROSS THE EASTERN U.S. THROUGH EARLY NEXT WEEK. THERE IS SOME MODEL DIVERGENCE IN THE EXACT PLACEMENT AND STRENGTH OF THE EASTERN U.S. UPPER TROUGH BY THE LATTER HALF OF NEXT WEEK...BUT BOTH THE GFS AND ECMWF MAINTAIN THIS FEATURE THROUGH THE PERIOD. SURFACE FEATURES SHOW SIMILAR SLIGHT DEPARTURES BETWEEN THE MODELS...BUT THE GENERAL THEME AMONG THE MEDIUM RANGE MODELS IS FOR GEORGIA TO BE ON THE NORTHWEST SIDE OF THE WESTERN ATLANTIC RIDGE WITH PERSISTENT WEAK TROUGHING IN THE LEE OF THE APPALACHIANS EXTENDING SOUTHWEST INTO THE FORECAST AREA. THIS SHOULD PROVIDE AMPLE MOISTURE OVER THE REGION FOR AT LEAST SCATTERED CONVECTION THROUGH THE PERIOD...WITH A NORMAL SUMMERTIME DIURNAL BIAS. ANY WEAK RIPPLES MOVING THROUGH THE UPPER FLOW WILL ENHANCE CONVECTIVE CHANCES...BUT TIMING OF ANY SUCH FEATURES ARE PROBLEMATIC AT BEST IN THE EXTENDED FORECAST PERIOD AND WITH THE LACK OF ANY CONSENSUS BETWEEN THE MODELS CONCERNING ANY LARGER...MORE ORGANIZED WAVES I HAVE CHOSEN TO KEEP POPS BELOW LIKELY THROUGH THE PERIOD. 20 && .AVIATION... 8Z UPDATE... SATELLITE LOOP SHOWS CU FIELD DEVELOPING ACROSS THE REGION THIS AFTERNOON WITH SOME ISOLATED SHOWERS NORTH AND SOUTH OF THE TAF SITES. SO FAR THE PRECIP HAS STAYED AWAY FROM THE TAF SITES BUT THE HRRR SHOWS A CLUSTER OF SHRA/TSRA DEVELOPING JUST WEST OF ATL BY 00Z. WILL KEEP THE TEMPO GROUP IN FROM 21 TO 01 TO COVER THIS AND WILL HAVE TO KEEP AN EYE ON THE SITUATION. WINDS ARE MAINLY 6KT OR LESS OUT OF THE SW BUT AM SEEING SOME SE WINDS AT TIMES. CEILINGS AND VSBYS SHOULD STAY VFR THROUGH THE PERIOD EXCEPT IN AND AROUND SHRA/TSRA DEVELOPMENT. //ATL CONFIDENCE...18Z UPDATE... CONFIDENCE MEDIUM TO HIGH ON ALL ELEMENTS 01 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 88 72 87 / 20 50 50 50 ATLANTA 72 87 73 85 / 20 60 60 50 BLAIRSVILLE 68 84 67 81 / 20 50 50 60 CARTERSVILLE 70 89 70 86 / 20 50 50 50 COLUMBUS 73 89 73 89 / 30 60 60 50 GAINESVILLE 72 87 72 84 / 20 50 50 50 MACON 72 89 72 89 / 30 60 60 50 ROME 70 89 70 87 / 20 50 50 50 PEACHTREE CITY 71 87 71 86 / 20 60 60 50 VIDALIA 72 89 73 89 / 40 60 60 50 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...01 LONG TERM....11 AVIATION...01
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
156 PM EDT FRI JUL 19 2013 .PREV DISCUSSION... /ISSUED 727 AM EDT FRI JUL 19 2013/ SHORT TERM /TODAY THROUGH TONIGHT/... /ISSUED AT 349 AM EDT FRI JUL 19 2013/ FOR THIS MORNING...SCATTERED SHOWERS HAVE MOVED OFF THE ATLANTIC AND INTO SOUTHEAST GA. SOME OF THESE WILL MOVE INTO THE SOUTHEAST CORNER OF THE CWA EARLY THIS MORNING AND SPREAD WESTWARD ACROSS THE REST OF CENTRAL GA THIS MORNING. DAYTIME HEATING WILL AID IN CONVECTION THIS AFTERNOON WITH THE BEST RISK IN THE MOUNTAINS AND ALSO CENTRAL GA. LATEST MODELS SHOW THE SURGE OF MOISTURE EXPECTED FOR TODAY IS COMING IN MUCH SLOWER THAN PREVIOUS RUNS...BRINGING IT INTO THE CWA SATURDAY AFTERNOON. THE H5 LOW WILL FINALLY OPEN INTO A SHORT WAVE TROUGH BY SATURDAY AFTERNOON AND THIS WILL PUT THE CWA IN A SOUTHWEST FLOW. BOTH GFS/NAM INDICATE A SIGNIFICANT SHORT WAVE MOVING INTO THE CWA SATURDAY AFTERNOON AND THIS SHOULD BRING SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. 17 LONG TERM /SATURDAY THROUGH THURSDAY/... /ISSUED AT 349 AM EDT FRI JUL 19 2013/ MEDIUM RANGE MODELS START OUT QUITE SIMILAR TO BEGIN THE EXTENDED FORECAST PERIOD WITH A BROAD WEAKNESS IN THE UPPER FLOW OVER THE REGION THROUGH THE WEEKEND AS WEAK UPPER TROUGHING TAKES SHAPE ACROSS THE EASTERN U.S. THROUGH EARLY NEXT WEEK. THERE IS SOME MODEL DIVERGENCE IN THE EXACT PLACEMENT AND STRENGTH OF THE EASTERN U.S. UPPER TROUGH BY THE LATTER HALF OF NEXT WEEK...BUT BOTH THE GFS AND ECMWF MAINTAIN THIS FEATURE THROUGH THE PERIOD. SURFACE FEATURES SHOW SIMILAR SLIGHT DEPARTURES BETWEEN THE MODELS...BUT THE GENERAL THEME AMONG THE MEDIUM RANGE MODELS IS FOR GEORGIA TO BE ON THE NORTHWEST SIDE OF THE WESTERN ATLANTIC RIDGE WITH PERSISTENT WEAK TROUGHING IN THE LEE OF THE APPALACHIANS EXTENDING SOUTHWEST INTO THE FORECAST AREA. THIS SHOULD PROVIDE AMPLE MOISTURE OVER THE REGION FOR AT LEAST SCATTERED CONVECTION THROUGH THE PERIOD...WITH A NORMAL SUMMERTIME DIURNAL BIAS. ANY WEAK RIPPLES MOVING THROUGH THE UPPER FLOW WILL ENHANCE CONVECTIVE CHANCES...BUT TIMING OF ANY SUCH FEATURES ARE PROBLEMATIC AT BEST IN THE EXTENDED FORECAST PERIOD AND WITH THE LACK OF ANY CONSENSUS BETWEEN THE MODELS CONCERNING ANY LARGER...MORE ORGANIZED WAVES I HAVE CHOSEN TO KEEP POPS BELOW LIKELY THROUGH THE PERIOD. 20 && .AVIATION... 18Z UPDATE... SATELLITE LOOP SHOWS CU FIELD DEVELOPING ACROSS THE REGION THIS AFTERNOON WITH SOME ISOLATED SHOWERS NORTH AND SOUTH OF THE TAF SITES. SO FAR THE PRECIP HAS STAYED AWAY FROM THE TAF SITES BUT THE HRRR SHOWS A CLUSTER OF SHRA/TSRA DEVELOPING JUST WEST OF ATL BY 00Z. WILL KEEP THE TEMPO GROUP IN FROM 21 TO 01 TO COVER THIS AND WILL HAVE TO KEEP AN EYE ON THE SITUATION. WINDS ARE MAINLY 6KT OR LESS OUT OF THE SW BUT AM SEEING SOME SE WINDS AT TIMES. CEILINGS AND VSBYS SHOULD STAY VFR THROUGH THE PERIOD EXCEPT IN AND AROUND SHRA/TSRA DEVELOPMENT. //ATL CONFIDENCE...18Z UPDATE... CONFIDENCE MEDIUM TO HIGH ON ALL ELEMENTS 01 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 90 71 88 72 / 20 20 50 50 ATLANTA 90 72 87 73 / 20 20 60 60 BLAIRSVILLE 87 68 84 67 / 30 20 50 50 CARTERSVILLE 91 70 89 70 / 20 20 50 50 COLUMBUS 94 73 89 73 / 40 30 60 60 GAINESVILLE 88 72 87 72 / 20 20 50 50 MACON 92 72 89 72 / 40 30 60 60 ROME 91 70 89 70 / 20 20 50 50 PEACHTREE CITY 89 71 87 71 / 20 20 60 60 VIDALIA 91 72 89 73 / 50 40 60 60 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...01 LONG TERM....11 AVIATION...01
AREA FORECAST DISCUSSION
NWS LINCOLN IL
859 PM CDT SAT JUL 20 2013 .DISCUSSION... ISSUED 858 PM CDT SAT JUL 20 2013 SOMEWHAT COMPLICATED SCENARIO FOR THE OVERNIGHT AS OPPOSED TO THE LAST SEVERAL NIGHTS. CONVECTION ALONG THE I-64 CORRIDOR HAS BEEN PERSISTENT THE LAST FEW HOURS. ALTHOUGH THE HEAVIEST RAIN IS NOW WELL SOUTH OF OUR AREA...THE EXTREME SOUTHEAST CWA HAS SEEN LIGHT TO MODERATE RAIN CONTINUING. THE FRONTAL BOUNDARY HAS BEGUN TO RETROGRADE WESTWARD...WITH IT APPEARING FAIRLY NICELY ON RADAR IMAGERY FROM JERSEYVILLE TO DECATUR TO JUST WEST OF CHAMPAIGN. LATEST RAP AND HRRR GUIDANCE DOES NOT SHOW MUCH IN THE WAY OF STEERING CURRENTS WHICH WOULD FULLY PUSH IT BACK SOUTHEAST OF THE AREA...BUT THEY INDICATE THAT IT SHOULD NOT GET TOO MUCH FURTHER NORTHWEST. WITH LIGHT WINDS...POOLING DEW POINTS NEAR 70 AND THE MOISTURE FROM THE HEAVIER RAIN POCKETS FROM EARLIER TODAY... HAVE SOME CONCERNS WITH FOG DEVELOPMENT ACROSS THE SOUTHEAST THIRD OF THE CWA DESPITE THE AMOUNT OF CLOUDS. HAVE ADDED SOME PATCHY FOG FOR THIS AREA OVERNIGHT. DID NOT REALLY CHANGE THE LOW TEMPERATURES...BUT HAD TO MAKE SOME SIGNIFICANT ADJUSTMENTS TO THE HOURLY TRENDS...ESPECIALLY IN THE SOUTHEAST DUE TO THE RAIN. UPDATED GRIDS HAVE BEEN SENT. EARLIER ZONE ISSUANCE AT 7 PM ALREADY TOOK INTO ACCOUNT MOST OF THE UPDATES...BUT WILL FRESHEN THIS AS WELL TO ADD THE FOG MENTION. GEELHART && .AVIATION... ISSUED 614 PM CDT SAT JUL 20 2013 COLD FRONT HAS PASSED THROUGH KDEC/KCMI OVER THE LAST HOUR OR SO. STILL SEEING SOME EXTENSIVE CLOUD COVER THERE DUE TO CONVECTION SOUTH OF THE FRONT IN SOUTHERN ILLINOIS...WITH CEILINGS BREAKING UP OVER THE NEXT COUPLE HOURS. OVERNIGHT CONCERN REMAINS WITH POTENTIAL FOR SOME MVFR CONDITIONS DUE TO LIGHT FOG...WITH THE WINDS REMAINING LIGHT OVERNIGHT AND TEMPERATURE/DEW POINT SPREADS FAIRLY MINIMAL DESPITE SOMEWHAT DRIER AIR FILTERING IN. LATER ON SUNDAY AFTERNOON...POTENTIAL FOR SCATTERED THUNDERSTORMS INCREASES FROM THE WEST...AS AN UPPER DISTURBANCE APPROACHES THE MISSISSIPPI VALLEY. HAVE INTRODUCED SOME VCTS AT KPIA/KSPI FOR THE LAST FEW HOURS OF THE FORECAST...BUT HELD OFF FURTHER EAST AS IT CURRENTLY APPEARS TO BE MORE OF AN EVENING THREAT IN THAT AREA. GEELHART && .PREV DISCUSSION... ISSUED 248 PM CDT SAT JUL 20 2013 MODELS LOOK IN VERY GOOD AGREEMENT IN THE SHORT TERM PERIOD...AS MAIN CONCERN IS PCPN CHANCES AND TEMPS. EXTENDED MODELS HAVE SOME DIFFERENCES BUT THEY ARE MINOR AND DO NOT CHANGE THE OVERALL FORECAST THAT MUCH...EXCEPT TO BRING IN SOME DRIER PERIODS DURING MIDDLE OF THE WEEK. SO OVERALL CONFIDENCE IN FORECAST IS GOOD. SHORT TERM...TONIGHT THROUGH TUESDAY FRONT HAS BEEN MOVING SOUTH THROUGH THE AREA TODAY AND WILL CONTINUE TO MOVE SOUTH LATE THIS AFTERNOON AND EVENING. THUNDERSTORMS HAVE DEVELOPED ALONG THE FRONT AS IT HAS INTERACTED WITH JUICY AIR WITH LOWER TO MIDDLE 70S DEWPOINTS. WITH THUNDERSTORMS THAT HAVE NOW DEVELOPED JUST NORTH OF I-70...WILL HAVE A LATE AFTERNOON PERIOD IN THE WORDED FORECAST ONCE IT IS ISSUED. OTHERWISE...TONIGHT THUNDERSTORMS WILL JUST BE IN THE SOUTHEAST JUST FOR THIS EVENING AND THEN DRY FOR AFTER MIDNIGHT. AS CAN BE SEEN ON VISIBLE SATELLITE AND RADAR IMAGES OUT WEST...THE FRONT EXTENDS BACK TO THE NORTHWEST WITH MORE SHOWERS AND THUNDERSTORMS. THIS FRONT WILL BE THE FOCUS FOR MORE DEVELOPMENT TOMORROW THAT WILL ADVECT TOWARD WESTERN ILLINOIS TOMORROW MORNING AND CENTRAL ILLINOIS TOMORROW AFTERNOON. THUNDERSTORM CHANCES WILL CONTINUE INTO TOMORROW NIGHT AS A SHORT WAVE MOVES ACROSS THE AREA AS WELL. POPS WILL BE HIGHEST TOMORROW NIGHT DUE TO THIS SHORT WAVE AS WELL. PCPN CHANCES WILL CONTINUE INTO MONDAY...THOUGH LOWER...AS THE SHORT WAVE MOVES EAST OF THE AREA. A SECOND WAVE OR MCS WILL THEN DEVELOP OUT WEST AND MOVE INTO THE AREA FOR MON NIGHT INTO TUESDAY. THIS WILL BRING CONTINUED THUNDERSTORM CHANCES FROM WEST TO EAST. CHANCES THEN DIMINISH FROM THE WEST TUE INTO TUE NIGHT. TEMP WILL REMAIN WARM AND WITH HIGH DEWPOINTS...MUGGY CONDITIONS WILL CONTINUE. AFTERNOON HIGHS ARE EXPECTED TO STILL REACH INTO THE MIDDLE TO UPPER 80S WITH NEAR 90 DEGREES IN THE SOUTHEAST ON MONDAY. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY AS THE SECOND WAVE MOVES THROUGH THE AREA...THUNDERSTORMS WILL PROBABLY STILL BE POSSIBLE IN THE SOUTHEAST SECTIONS FOR TUE NIGHT...SO WILL KEEP CHC POPS THERE. THIS SECOND WAVE SHOULD BE STRONG ENOUGH TO PUSH THE FRONT WELL SOUTH AND BRING A PERIOD OF DRY WEATHER TO THE AREA. UPPER LEVEL FLOW WILL ALSO BE OUT OF THE NORTHWEST...SO CONDITIONS SHOULD BE A TAD COOLER DURING THE DAY. CURRENT EXTENDED MODELS INDICATE THAT DRY WEATHER WILL PREVAIL THROUGH THURSDAY NIGHT AS MODELS DO NOT SHOW ANY SHORT WAVES MOVING THROUGH THE AREA DURING THAT PERIOD. HOWEVER...MODELS DO NOT DO WELL WITH SMALL WEAK FEATURES IN NORTHWEST FLOW SO DON`T BE SURPRISED IF THIS CHANGES OVER THE NEXT COUPLE OF DAYS. THE NEXT REAL CHANCE OF SHOWERS AND THUNDERSTORMS APPEARS NOT TO BE UNTIL FRIDAY THROUGH SATURDAY AS A MID LEVEL TROUGH MOVES TOWARD THE AREA. CURRENTLY THIS SYSTEM LOOKS TO REMAIN WEST OF THE AREA BUT STILL BRING PCPN TO ALL OF CENTRAL AND SOUTHEAST ILLINOIS FOR END OF THE WEEK. TEMPS WILL REMAIN AROUND NORMAL BUT THEN BECOME COOLER... POSSIBLY...AT THE END OF THE WEEK AND BEGINNING OF THE WEEKEND. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
552 PM CDT FRI JUL 19 2013 .MESOSCALE DISCUSSION...540 PM... ISOLATED CONVECTION IS DEVELOPING ALONG THE COOL FRONT AND A SUBTLE PRE-FRONTAL WIND CONVERGENCE FROM CENTRAL WI INTO SOUTHEAST IA LATE THIS AFTERNOON. THIS NOW LOOKS TO BE THE ONLY FOCUS FOR STORM ACTIVITY WITH THE REST OF THE CU HAVING DISSIPATED ACROSS THE REGION. THE COOL FRONT IS WELL-DEFINED ON OBSERVATIONS AND SATELLITE AND EASING ITS WAY SOUTHEAST AT 15 KT. WATER VAPOR AND PROFILERS INDICATE GRADUALLY INCREASE UPPER TO MID-LEVEL FLOW IS SETTLING SOUTH ACROSS THE UPPER MISSISSIPPI VALLEY ASSOCIATED WITH THE UPPER TROUGH. THIS MAY BE PROVIDING SOME BROAD ASCENT TO HELP CONVECTION TO DEVELOP AS WELL. THE MAIN PRESSURE RISES AND MOMENTUM BEHIND THE FRONT IS SHIFTING MORE EAST THAN SOUTH ACROSS WI AND THUS IT CONTINUES TO BE CONCERNING JUST HOW SHARP CONVERGENCE WILL OR WILL NOT BE THROUGH THE EVENING AS THE FRONT APPROACHES AND MOVES INTO THE FORECAST AREA. ALSO...THE FRONT IS NOW GOING AGAINST THE DIURNAL GRAIN AND MOST OF THE LOW-LEVEL JET AND MOISTURE TRANSPORT FOCUS IS TO THE NORTHEAST OF THE FORECAST AREA. SO THIS POINTS TOWARD SCATTERED CONVECTION ONLY...MAYBE AT BEST...WITH THE FRONTAL PASSAGE. ANY STORMS THAT DEVELOP WILL STILL HAVE PLENTY OF INSTABILITY WITH SFC BASED CAPE ON RAP AND LAPS OF 2000 TO 3000 J/KG AND ASSOCIATED LARGE VALUES OF DOWNDRAFT CAPE. THUS STORMS COULD FESTER/DEVELOP ON OUTFLOWS AHEAD OF THE FRONT IF ANY CAN SUSTAIN THEMSELVES. EVEN WITH THAT THOUGH...THINK COVERAGE WILL BE LIMITED AND MORE SO THAN WHAT SEVERAL CONVECTIVE ALLOWING MODELS ARE SHOWING. CONVECTION COULD CONCEIVABLY COME UP THE NEXT COUPLE HOURS AND THEN WANE AS IT MOVES INTO THE FORECAST AREA. POPS HAVE BEEN ADJUSTED AND LOWERED SOME TO ACCOUNT FOR LESS COVERAGE WITH THE FRONT. MTF && .DISCUSSION... 316 PM CDT THE MAIN FORECAST CONCERNS WILL FIRST FOCUS ON CONVECTIVE TRENDS THIS EVENING AND OVERNIGHT...AND ALSO THE HEAT THROUGH THIS EVENING. HOWEVER...OTHER CONCERNS IN THE FORECAST PERIOD WILL BE ADDITIONAL THREATS OF CONVECTION/MCS`S LATER THIS WEEKEND INTO EARLY NEXT WEEK. A COLD FRONTAL BOUNDARY IS CURRENTLY DROPPING SOUTHWARD ACROSS SOUTHERN WISCONSIN. LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY HAS REMAINED FAIRLY WEAK AS A WELL MIXED WARM SECTOR HAS PRODUCED SOUTHWESTERLY FLOW RELATIVELY PARALLEL WITH THE SURFACE FRONT. AS A RESULT OF THIS...STORM DEVELOPMENT HAS REMAINED ISOLATED THUS FAR. IN SPITE OF THIS ADDITIONAL STORMS ARE STILL EXPECTED TO DEVELOP THROUGH THE AFTERNOON. FOR MORE INFO ON THESE STORMS REFERENCE THE MESO DISCUSSION ABOVE. THUNDERSTORMS WILL LIKELY BECOME HIGHER IN AERIAL COVERAGE EARLY THIS EVENING AS LOWER LEVEL MOISTURE CONVERGENCE INCREASES AHEAD THIS BOUNDARY. IT APPEARS THE FRONT WILL BE SLOW TO CLEAR NORTHERN ILLINOIS...POSSIBLY NOT PASSING SOUTH OF CHICAGO UNTIL AFTER 03 UTC THIS EVENING. THEREFORE...THUNDERSTORMS WILL BE POSSIBLY THROUGH AT LEAST EARLY TO MID EVENING ACROSS MUCH OF ILLINOIS. THERE WILL STILL BE A THREAT FOR STORMS TO PRODUCE MICROBURSTS WITH ISOLATED AREAS OF STRONG DAMAGING WINDS INTO THIS EVENING AS DOWNDRAFT CAPE WILL REMAIN IN EXCESS OF 1,000 J/KG. HOWEVER...THE OTHER THREAT WILL BE TORRENTIAL DOWNPOURS WITH THESE THUNDERSTORMS. THE RICH THETA-E AIR...WITH PWATS UP AROUND 2 INCHES WILL PROVIDE AMPLE CONDITIONS FOR VERY HEAVY RAINFALL FROM THESE STORMS. MY CONCERN IS THAT AS THE LOWER LEVEL CONVERGENCE INCREASES ALONG THE LOWER LEVEL FRONTAL ZONE...THAT SOME OF THESE STORMS COULD TRAIN...WITH A NEARLY EASTERLY CLOUD BEARING FLOW AROUND 25 KT EXPECTED...WHICH SHOULD BE NEARLY PARALLEL TO THE BOUNDARY. IT APPEARS THE MAIN THREAT FOR THIS WILL BE PRIMARILY SOUTH OF CHICAGO ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN ILLINOIS COUNTIES. I HAVE MAINTAINED THE HEAVY RAIN WORDING IN THESE AREAS...ESPECIALLY THIS EVENING. THESE STORMS COULD EASY DROP 1 TO 2 INCHES PER HOUR...AND IF THE STORMS TRAIN OVER THE SAME AREAS THERE COULD BE SOME LOCALIZED AREAS OF HIGH RAINFALL AMOUNTS. THIS WILL NEED TO BE WATCHED THIS EVENING. CONFIDENCE IN WIDESPREAD HYDRO CONCERNS IN LOW...THEREFORE NO HEADLINES ARE PLANNED. THE THREAT FOR THUNDERSTORMS WITH HEAVY RAIN COULD CONTINUE OVERNIGHT ACROSS MY FAR SOUTHERN COUNTIES AS IT APPEARS THE FRONTAL BOUNDARY WILL BE SLOW TO MOVE ACROSS THESE AREAS. HOWEVER...IT APPEARS THAT THE FRONT SHOULD CLEAR THE AREA BY EARLY SATURDAY MORNING...ENDING THE THREAT FOR STORMS. I WILL LEAVE THE HEAT HEADLINES AS IS...WITH AN ENDING TIME AT 00 UTC THIS EVENING. WITH THE DEW POINTS MIXING OUT INTO THE UPPER 60S THE HEAT INDEX HAS NOT BEEN MUCH ABOVE 100. SO ALTHOUGH THE FRONT WILL NOT MOVE THROUGH TILL TONIGHT...IT APPEARS THE BIG HEAT WILL BE OVER BY 00 UTC...WITH COOLER AND LESS HUMID AIR TO MOVE IN LATER TONIGHT. SATURDAY AND SUNDAY WILL BE COOLER...WITH HIGHS MAINLY IN THE LOW TO MID 80S...WITH AN ONSHORE FLOW. DRY CONDITIONS ARE EXPECTED FOR MUCH OF THE WEEKEND. HOWEVER...THE CHANCE FOR MORE STORMS WILL INCREASE LATE SUNDAY AND SUNDAY NIGHT AS ANOTHER DISTURBANCE APPROACHES THE AREA. IT CURRENTLY APPEARS THE MAIN FOCUS MAY BE ACROSS THE SOUTHERN HALF TO TWO THIRDS OF MY AREA...BUT THE POTENTIAL FOR SOME ADDITIONAL HEAVY RAIN AREA POSSIBLE INTO EARLY MONDAY. SUBSIDENCE IN THE WAKE OF THIS DISTURBANCE MAY LEAD TO LITTLE TO NO CONVECTIVE ACTIVITY MONDAY AFTERNOON AND NIGHT. I HAVE THEREFORE TRENDED POPS DOWN SIGNIFICANTLY FOR THIS TIMEFRAME. HOWEVER...A FAIRLY DISTURBED WEST-NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL CONUS WILL LIKELY DRIVE ANOTHER DISTURBANCE OR TWO ACROSS THE AREA ON TUESDAY. THIS WILL PRODUCE ANOTHER DECENT CHANCE OF THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. ONCE THIS DISTURBANCE MOVES THROUGH...THE FLOW ALOFT LOOKS TO AMPLIFY SOME...WITH BUILDING HEIGHTS ACROSS THE WESTERN CONUS. THIS SHOULD ALLOW A COLD FRONT AND AREA OF SURFACE HIGH PRESSURE TO SHIFT SOUTHWARD ACROSS THE GREAT LAKES REGION. THIS SHOULD RESULT IN THE MAIN THREAT FOR CONVECTIVE ACTIVITY SHIFTING SOUTH OF THE REGION FOR WEDNESDAY THROUGH THURSDAY...WITH A CONTINUATION OF COOL TEMPERATURES INTO LATER NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * ISOLD-SCT SHRA/TSRA STILL POSSIBLE BUT HAVE SLOWED TIMING TO 01-04Z. * GUSTY SW WINDS BETWEEN 20-25KT WITH A FEW GUSTS TO 30 KT THRU EARLY THIS EVE. * WIND DIR SHIFTING FROM WEST TO NORTH LATE THIS EVENING. THEN WINDS STEADILY TURN NORTHEAST BY DAYBREAK SAT. SPEEDS TONIGHT THRU MIDDAY SAT WILL GENERALLY BE 7-10KT. MDB //DISCUSSION...UPDATED 22Z... CONTINUING TO MONITOR TSRA POTENTIAL INTO THE EVENING. COLD FRONTAL BOUNDARY FROM ROUGHLY GRB TO DLL TO PDC AT 22Z. SATELLITE SHOWS SEVERAL NARROW BANDS OF FAIRLY WELL DEVELOPED CU WITH THE CU RIGHT ALONG THE FRONT STARTING TO CATCH UP TO THE BAND FURTHER AHEAD OF IT. DEVELOPMENT IS STARTING TO OCCUR AND COVERAGE MAY INCREASE TO A DEGREE OVER THE NEXT HOUR AS THE TWO BANDS OF CU MEET. ANY ACTIVITY THAT DOES DEVELOP WILL STILL BE SEVERAL HOURS OUT FROM THE TERMINALS AND HAVE FURTHER SLOWED MENTION IN THE TAFS...WITH ADDITIONAL SLOWING POSSIBLE. COVERAGE IS STILL IN QUESTION...ESPECIALLY WITH EARLIEST ARRIVAL NEAR THE TERMINALS COMING CLOSER TO SUNSET SO ACTIVITY COULD BE ON A DOWNWARD TREND. MDB FROM 18Z... ATMOSPHERE OVER NORTHERN IL/NORTHWEST IN BEGINNING TO BECOME UNSTABLE AND PRIMED FOR ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST GUIDANCE CONTINUES TO FAVOR STEADILY INCREASED COVERAGE/INTENSITY OF THUNDERSTORMS BY 20-21Z. CUMULUS CLOUDS WILL THICKEN AND BUILD...AS THE CONVECTIVE POTENTIAL INCREASES. ALL OF THIS ACTIVITY WILL DEVELOP AHEAD OF THE FRONTAL BOUNDARY...WITH BREEZY CONDITIONS FROM THE SOUTHWEST. WINDS WILL GENERALLY BE THRU FRONTAL PASSAGE AND WITH PRECIP ARND 20-25KT. THEN BY 00-01Z TSRA COVERAGE WILL BEGIN TO DIMINISH AND SHIFT TO THE SOUTHEAST OF TAF SITES. EXPECT BY 02Z TSRA TO HAVE COME TO AN END WITH WINDS TURNING NORTH/NORTHEAST OVERNIGHT. THE GRADIENT BRIEFLY DIMINISHES LATE TONIGHT...WITH WINDS POSSIBLY COMING DOWN TO LESS THAN 7KT. SKIES WILL BECOME PARTLY CLOUDY WITH JUST A CIRRUS SHIELD OVERNIGHT. JUST AFT DAYBREAK SAT WIND SPEEDS WILL INCREASE TO 12-15KT WITH MOSTLY CLEAR SKIES...THEN EXPECT DIURNAL CUMULUS CLOUDS TO DEVELOP WITH BASES ARND 4KFT AGL...THIS SHUD HELP TO TRIM WINDS BACK TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 22Z... * MEDIUM-HIGH CONFIDENCE IN TIMING OF TSRA POTENTIAL...MEDIUM CONFIDENCE IN OCCURRENCE. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * HIGH CONFIDENCE IN WINDS TURNING NORTHEAST BY DAYBREAK SAT. MDB //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. WX NIL. SUNDAY...CHANCE OF TSRA AFTERNOON THROUGH OVERNIGHT. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES TSRA. THURSDAY...VFR. WX NIL. KREIN && .MARINE... 329 PM CDT INITIAL CONCERN IN THE NEARSHORE WITH GUSTY WEST-SOUTHWEST WINDS OCCASIONALLY TO 30 KT AHEAD OF A COLD FRONT. WITH SLOW PROGRESS OF FRONT...IT IS POSSIBLE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED FOR A FEW HOURS INTO MID EVENING. ALSO A FEW GUSTY STORMS ARE POSSIBLE THROUGH EARLY EVENING...WITH AN OUTSIDE CHANCE FOR GUSTS OVER 50 KT. THIS INCLUDES THE OPEN WATERS. BEHIND THE FRONT...A STRONG PUSH OF COOL AIR FOR THIS TIME OF YEAR WILL MOVE DOWN THE LAKE RESULTING IN INCREASING NORTHERLY WINDS...FIRST ON THE NORTH HALF SHIFTING TO THE SOUTH HALF DURING THE DAY SATURDAY. THERE MAY BE OCCASIONAL GUSTS TO 30 KT OVER THE OPEN WATERS. THEN HIGH PRESSURE WILL BUILD OVER THE LAKE BY SUNDAY AND WINDS WILL DIMINISH. THOUGH LOW PRESSURE WILL MOVE OVER THE REGION EARLY NEXT WEEK AND A COLD FRONT WILL PUSH ACROSS THE LAKE BY TUESDAY...WINDS LOOK TO REMAIN FAIRLY LIGHT OUT OF THE SOUTH UNTIL THE COLD FRONT PASSAGE. THEN AFTER THE FRONTAL PASSAGE LATE TUESDAY...THERE COULD POTENTIALLY BE A PERIOD OF MODESTLY STRONGER NORTHERLY WINDS FOLLOWED BY AN EXTENDED PERIOD OF LIGHT WINDS MID TO LATE NEXT WEEK AS HIGH PRESSURE SPREADS ACROSS THE GREAT LAKES. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 PM FRIDAY. IN...HEAT ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 PM FRIDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
510 PM CDT FRI JUL 19 2013 .MESOSCALE DISCUSSION... CONTINUING TO MONITOR CONVECTIVE CHANCES THIS AFTERNOON INTO EARLY EVENING WITH TRENDS SLOW TO GO THUS FAR AND CONTINUING TO APPEAR THAT ANY SEVERE THREAT WOULD BE ISOLATED IN COVERAGE. AS THE UPPER TROUGH CONTINUES TO DIG INTO THE FAR NORTHERN GREAT LAKES THIS AFTERNOON...A NARROW PLUME OF DEEPER MOISTURE IN ADVANCE AS SEEN ON WATER VAPOR HAS MOVED EAST INTO NORTHERN IL. THERE HAS BEEN ACCAS AND AGITATED CU WITHIN THIS STREAM...ALONG WITH SPORADIC ISOLATED SHOWERS ACROSS SOUTHERN WI AND NOW INTO NORTHERN BOONE COUNTY IL. SUBTLE PRE-FRONTAL SURFACE CONVERGENCE IS NOTED IN OBSERVATIONS UNDER THIS...BUT IT HAS BECOME PROGRESSIVELY LESS CONVERGENT AS THE BOUNDARY LAYER HAS BECOME WELL-MIXED. GIVEN THAT AN NO NOTICEABLE TRENDS ON SATELLITE OR RADAR DO NOT FORESEE ANY WIDESPREAD CONVECTIVE GROWTH ON THIS...ALTHOUGH ISOLATED TO SCATTERED STORMS COULD DEVELOP OR FESTER...PROBABLY MOST FAVORED ACROSS FAR NORTHEAST IL. FURTHER TO THE SOUTH A REMNANT ELEVATED OUTFLOW AS SEEN EARLIER ON SATELLITE AND RADAR HAS STALLED ACROSS FAR NORTHERN IN SOUTHWEST OVER KANKAKEE AND PONTIAC. THIS HAS TRIGGERED SOME CU WITH BETTER VERTICAL GROWTH ALONG WITH SHOWERS NOW BEING SEEN ALONG THE IN/MI BORDER WHERE CONVERGENCE APPEARS MORE DEFINED ON STREAMLINE ANALYSIS. AN AREA OF 73-75 DEW POINTS ACROSS EAST CENTRAL IL IS FEEDING INTO THIS AREA LEADING TO MLCAPES OF 3000-3500 J/KG. SIMILAR HERE...ISOLATED TO SCATTERED STORM DEVELOPMENT COULD BE SEEN...WITH SLOW MOVING CELLS IF ANYTHING CAN DEVELOP AS THE ACTIVITY IS FURTHER REMOVED FROM THE BETTER STEERING FLOW TO THE NORTH. OVERALL IT IS TRENDING THAT STORM CHANCES MAY BE BEST IN THE FORECAST AREA JUST AHEAD OF THE COOL FRONT WHICH AS OF 230 PM IS DRAPED FROM NORTHERN LAKE MI TO JUST SOUTH OF LA CROSSE WI. EVEN THEN THE COVERAGE COULD BE LIMITED. TOWERING CU HAS BEEN SEEN ALONG THIS AND THIS MAY FURTHER GROW AS THE FRONT UNDERCUTS THE AFOREMENTIONED DEEPER MOISTURE ALOFT BY LATE THIS AFTERNOON. SUBTLE SHORT WAVE ENERGY TRACKING EAST ACROSS NORTHERN IA COULD INTERACT WITH THIS TO HELP SPRING ACTIVITY...BUT IT MAY STRUGGLE LASTING DEEP INTO THE EVE AT LEAST WITH STRONG POTENTIAL GIVEN THE DIURNAL HEATING OF THE DAY HAVING WANED. CONVECTIVE ALLOWING GUIDANCE HAS QUITE A BIT OF RANGE IN SOLUTIONS...WHICH DOES NOT HELP TO BOLSTER CONFIDENCE ANY. LAPS AND RAP ANALYSIS AND SOUNDINGS INDICATE LARGE VALUES OF DCAPE /1100+ J/KG/ WHICH COMBINED WITH PRECIPITATION LOADING CONCERNS COULD FAVOR ISOLATED WET MICROBURSTS IN ANY STORMS...WHICH REMAINS THE PRIMARY CONCERN. DEEP LAYER SHEAR IS SLOWLY INCREASING JUST NOW APPROACHING 30 KT NEAR THE IL/WI BORDER...BUT IN GENERAL REMAINS WEAK ELSEWHERE. OBVIOUSLY THE HIGH PWATS CONTINUE TO SUPPORT HEAVY RAIN IN ANY STORM. MTF && .DISCUSSION... 316 PM CDT THE MAIN FORECAST CONCERNS WILL FIRST FOCUS ON CONVECTIVE TRENDS THIS EVENING AND OVERNIGHT...AND ALSO THE HEAT THROUGH THIS EVENING. HOWEVER...OTHER CONCERNS IN THE FORECAST PERIOD WILL BE ADDITIONAL THREATS OF CONVECTION/MCS`S LATER THIS WEEKEND INTO EARLY NEXT WEEK. A COLD FRONTAL BOUNDARY IS CURRENTLY DROPPING SOUTHWARD ACROSS SOUTHERN WISCONSIN. LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY HAS REMAINED FAIRLY WEAK AS A WELL MIXED WARM SECTOR HAS PRODUCED SOUTHWESTERLY FLOW RELATIVELY PARALLEL WITH THE SURFACE FRONT. AS A RESULT OF THIS...STORM DEVELOPMENT HAS REMAINED ISOLATED THUS FAR. IN SPITE OF THIS ADDITIONAL STORMS ARE STILL EXPECTED TO DEVELOP THROUGH THE AFTERNOON. FOR MORE INFO ON THESE STORMS REFERENCE THE MESO DISCUSSION ABOVE. THUNDERSTORMS WILL LIKELY BECOME HIGHER IN AERIAL COVERAGE EARLY THIS EVENING AS LOWER LEVEL MOISTURE CONVERGENCE INCREASES AHEAD THIS BOUNDARY. IT APPEARS THE FRONT WILL BE SLOW TO CLEAR NORTHERN ILLINOIS...POSSIBLY NOT PASSING SOUTH OF CHICAGO UNTIL AFTER 03 UTC THIS EVENING. THEREFORE...THUNDERSTORMS WILL BE POSSIBLY THROUGH AT LEAST EARLY TO MID EVENING ACROSS MUCH OF ILLINOIS. THERE WILL STILL BE A THREAT FOR STORMS TO PRODUCE MICROBURSTS WITH ISOLATED AREAS OF STRONG DAMAGING WINDS INTO THIS EVENING AS DOWNDRAFT CAPE WILL REMAIN IN EXCESS OF 1,000 J/KG. HOWEVER...THE OTHER THREAT WILL BE TORRENTIAL DOWNPOURS WITH THESE THUNDERSTORMS. THE RICH THETA-E AIR...WITH PWATS UP AROUND 2 INCHES WILL PROVIDE AMPLE CONDITIONS FOR VERY HEAVY RAINFALL FROM THESE STORMS. MY CONCERN IS THAT AS THE LOWER LEVEL CONVERGENCE INCREASES ALONG THE LOWER LEVEL FRONTAL ZONE...THAT SOME OF THESE STORMS COULD TRAIN...WITH A NEARLY EASTERLY CLOUD BEARING FLOW AROUND 25 KT EXPECTED...WHICH SHOULD BE NEARLY PARALLEL TO THE BOUNDARY. IT APPEARS THE MAIN THREAT FOR THIS WILL BE PRIMARILY SOUTH OF CHICAGO ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN ILLINOIS COUNTIES. I HAVE MAINTAINED THE HEAVY RAIN WORDING IN THESE AREAS...ESPECIALLY THIS EVENING. THESE STORMS COULD EASY DROP 1 TO 2 INCHES PER HOUR...AND IF THE STORMS TRAIN OVER THE SAME AREAS THERE COULD BE SOME LOCALIZED AREAS OF HIGH RAINFALL AMOUNTS. THIS WILL NEED TO BE WATCHED THIS EVENING. CONFIDENCE IN WIDESPREAD HYDRO CONCERNS IN LOW...THEREFORE NO HEADLINES ARE PLANNED. THE THREAT FOR THUNDERSTORMS WITH HEAVY RAIN COULD CONTINUE OVERNIGHT ACROSS MY FAR SOUTHERN COUNTIES AS IT APPEARS THE FRONTAL BOUNDARY WILL BE SLOW TO MOVE ACROSS THESE AREAS. HOWEVER...IT APPEARS THAT THE FRONT SHOULD CLEAR THE AREA BY EARLY SATURDAY MORNING...ENDING THE THREAT FOR STORMS. I WILL LEAVE THE HEAT HEADLINES AS IS...WITH AN ENDING TIME AT 00 UTC THIS EVENING. WITH THE DEW POINTS MIXING OUT INTO THE UPPER 60S THE HEAT INDEX HAS NOT BEEN MUCH ABOVE 100. SO ALTHOUGH THE FRONT WILL NOT MOVE THROUGH TILL TONIGHT...IT APPEARS THE BIG HEAT WILL BE OVER BY 00 UTC...WITH COOLER AND LESS HUMID AIR TO MOVE IN LATER TONIGHT. SATURDAY AND SUNDAY WILL BE COOLER...WITH HIGHS MAINLY IN THE LOW TO MID 80S...WITH AN ONSHORE FLOW. DRY CONDITIONS ARE EXPECTED FOR MUCH OF THE WEEKEND. HOWEVER...THE CHANCE FOR MORE STORMS WILL INCREASE LATE SUNDAY AND SUNDAY NIGHT AS ANOTHER DISTURBANCE APPROACHES THE AREA. IT CURRENTLY APPEARS THE MAIN FOCUS MAY BE ACROSS THE SOUTHERN HALF TO TWO THIRDS OF MY AREA...BUT THE POTENTIAL FOR SOME ADDITIONAL HEAVY RAIN AREA POSSIBLE INTO EARLY MONDAY. SUBSIDENCE IN THE WAKE OF THIS DISTURBANCE MAY LEAD TO LITTLE TO NO CONVECTIVE ACTIVITY MONDAY AFTERNOON AND NIGHT. I HAVE THEREFORE TRENDED POPS DOWN SIGNIFICANTLY FOR THIS TIMEFRAME. HOWEVER...A FAIRLY DISTURBED WEST-NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL CONUS WILL LIKELY DRIVE ANOTHER DISTURBANCE OR TWO ACROSS THE AREA ON TUESDAY. THIS WILL PRODUCE ANOTHER DECENT CHANCE OF THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. ONCE THIS DISTURBANCE MOVES THROUGH...THE FLOW ALOFT LOOKS TO AMPLIFY SOME...WITH BUILDING HEIGHTS ACROSS THE WESTERN CONUS. THIS SHOULD ALLOW A COLD FRONT AND AREA OF SURFACE HIGH PRESSURE TO SHIFT SOUTHWARD ACROSS THE GREAT LAKES REGION. THIS SHOULD RESULT IN THE MAIN THREAT FOR CONVECTIVE ACTIVITY SHIFTING SOUTH OF THE REGION FOR WEDNESDAY THROUGH THURSDAY...WITH A CONTINUATION OF COOL TEMPERATURES INTO LATER NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * ISOLD-SCT SHRA/TSRA STILL POSSIBLE BUT HAVE SLOWED TIMING TO 01-04Z. * GUSTY SW WINDS BETWEEN 20-25KT WITH A FEW GUSTS TO 30 KT THRU EARLY THIS EVE. * WIND DIR SHIFTING FROM WEST TO NORTH LATE THIS EVENING. THEN WINDS STEADILY TURN NORTHEAST BY DAYBREAK SAT. SPEEDS TONIGHT THRU MIDDAY SAT WILL GENERALLY BE 7-10KT. MDB //DISCUSSION...UPDATED 22Z... CONTINUING TO MONITOR TSRA POTENTIAL INTO THE EVENING. COLD FRONTAL BOUNDARY FROM ROUGHLY GRB TO DLL TO PDC AT 22Z. SATELLITE SHOWS SEVERAL NARROW BANDS OF FAIRLY WELL DEVELOPED CU WITH THE CU RIGHT ALONG THE FRONT STARTING TO CATCH UP TO THE BAND FURTHER AHEAD OF IT. DEVELOPMENT IS STARTING TO OCCUR AND COVERAGE MAY INCREASE TO A DEGREE OVER THE NEXT HOUR AS THE TWO BANDS OF CU MEET. ANY ACTIVITY THAT DOES DEVELOP WILL STILL BE SEVERAL HOURS OUT FROM THE TERMINALS AND HAVE FURTHER SLOWED MENTION IN THE TAFS...WITH ADDITIONAL SLOWING POSSIBLE. COVERAGE IS STILL IN QUESTION...ESPECIALLY WITH EARLIEST ARRIVAL NEAR THE TERMINALS COMING CLOSER TO SUNSET SO ACTIVITY COULD BE ON A DOWNWARD TREND. MDB FROM 18Z... ATMOSPHERE OVER NORTHERN IL/NORTHWEST IN BEGINNING TO BECOME UNSTABLE AND PRIMED FOR ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST GUIDANCE CONTINUES TO FAVOR STEADILY INCREASED COVERAGE/INTENSITY OF THUNDERSTORMS BY 20-21Z. CUMULUS CLOUDS WILL THICKEN AND BUILD...AS THE CONVECTIVE POTENTIAL INCREASES. ALL OF THIS ACTIVITY WILL DEVELOP AHEAD OF THE FRONTAL BOUNDARY...WITH BREEZY CONDITIONS FROM THE SOUTHWEST. WINDS WILL GENERALLY BE THRU FRONTAL PASSAGE AND WITH PRECIP ARND 20-25KT. THEN BY 00-01Z TSRA COVERAGE WILL BEGIN TO DIMINISH AND SHIFT TO THE SOUTHEAST OF TAF SITES. EXPECT BY 02Z TSRA TO HAVE COME TO AN END WITH WINDS TURNING NORTH/NORTHEAST OVERNIGHT. THE GRADIENT BRIEFLY DIMINISHES LATE TONIGHT...WITH WINDS POSSIBLY COMING DOWN TO LESS THAN 7KT. SKIES WILL BECOME PARTLY CLOUDY WITH JUST A CIRRUS SHIELD OVERNIGHT. JUST AFT DAYBREAK SAT WIND SPEEDS WILL INCREASE TO 12-15KT WITH MOSTLY CLEAR SKIES...THEN EXPECT DIURNAL CUMULUS CLOUDS TO DEVELOP WITH BASES ARND 4KFT AGL...THIS SHUD HELP TO TRIM WINDS BACK TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 22Z... * MEDIUM-HIGH CONFIDENCE IN TIMING OF TSRA POTENTIAL...MEDIUM CONFIDENCE IN OCCURRENCE. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * HIGH CONFIDENCE IN WINDS TURNING NORTHEAST BY DAYBREAK SAT. MDB //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. WX NIL. SUNDAY...CHANCE OF TSRA AFTERNOON THROUGH OVERNIGHT. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES TSRA. THURSDAY...VFR. WX NIL. KREIN && .MARINE... 329 PM CDT INITIAL CONCERN IN THE NEARSHORE WITH GUSTY WEST-SOUTHWEST WINDS OCCASIONALLY TO 30 KT AHEAD OF A COLD FRONT. WITH SLOW PROGRESS OF FRONT...IT IS POSSIBLE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED FOR A FEW HOURS INTO MID EVENING. ALSO A FEW GUSTY STORMS ARE POSSIBLE THROUGH EARLY EVENING...WITH AN OUTSIDE CHANCE FOR GUSTS OVER 50 KT. THIS INCLUDES THE OPEN WATERS. BEHIND THE FRONT...A STRONG PUSH OF COOL AIR FOR THIS TIME OF YEAR WILL MOVE DOWN THE LAKE RESULTING IN INCREASING NORTHERLY WINDS...FIRST ON THE NORTH HALF SHIFTING TO THE SOUTH HALF DURING THE DAY SATURDAY. THERE MAY BE OCCASIONAL GUSTS TO 30 KT OVER THE OPEN WATERS. THEN HIGH PRESSURE WILL BUILD OVER THE LAKE BY SUNDAY AND WINDS WILL DIMINISH. THOUGH LOW PRESSURE WILL MOVE OVER THE REGION EARLY NEXT WEEK AND A COLD FRONT WILL PUSH ACROSS THE LAKE BY TUESDAY...WINDS LOOK TO REMAIN FAIRLY LIGHT OUT OF THE SOUTH UNTIL THE COLD FRONT PASSAGE. THEN AFTER THE FRONTAL PASSAGE LATE TUESDAY...THERE COULD POTENTIALLY BE A PERIOD OF MODESTLY STRONGER NORTHERLY WINDS FOLLOWED BY AN EXTENDED PERIOD OF LIGHT WINDS MID TO LATE NEXT WEEK AS HIGH PRESSURE SPREADS ACROSS THE GREAT LAKES. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 PM FRIDAY. IN...HEAT ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 PM FRIDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
329 PM CDT FRI JUL 19 2013 .MESOSCALE DISCUSSION...239 PM CDT CONTINUING TO MONITOR CONVECTIVE CHANCES THIS AFTERNOON INTO EARLY EVENING WITH TRENDS SLOW TO GO THUS FAR AND CONTINUING TO APPEAR THAT ANY SEVERE THREAT WOULD BE ISOLATED IN COVERAGE. AS THE UPPER TROUGH CONTINUES TO DIG INTO THE FAR NORTHERN GREAT LAKES THIS AFTERNOON...A NARROW PLUME OF DEEPER MOISTURE IN ADVANCE AS SEEN ON WATER VAPOR HAS MOVED EAST INTO NORTHERN IL. THERE HAS BEEN ACCAS AND AGITATED CU WITHIN THIS STREAM...ALONG WITH SPORADIC ISOLATED SHOWERS ACROSS SOUTHERN WI AND NOW INTO NORTHERN BOONE COUNTY IL. SUBTLE PRE-FRONTAL SURFACE CONVERGENCE IS NOTED IN OBSERVATIONS UNDER THIS...BUT IT HAS BECOME PROGRESSIVELY LESS CONVERGENT AS THE BOUNDARY LAYER HAS BECOME WELL-MIXED. GIVEN THAT AN NO NOTICEABLE TRENDS ON SATELLITE OR RADAR DO NOT FORESEE ANY WIDESPREAD CONVECTIVE GROWTH ON THIS...ALTHOUGH ISOLATED TO SCATTERED STORMS COULD DEVELOP OR FESTER...PROBABLY MOST FAVORED ACROSS FAR NORTHEAST IL. FURTHER TO THE SOUTH A REMNANT ELEVATED OUTFLOW AS SEEN EARLIER ON SATELLITE AND RADAR HAS STALLED ACROSS FAR NORTHERN IN SOUTHWEST OVER KANKAKEE AND PONTIAC. THIS HAS TRIGGERED SOME CU WITH BETTER VERTICAL GROWTH ALONG WITH SHOWERS NOW BEING SEEN ALONG THE IN/MI BORDER WHERE CONVERGENCE APPEARS MORE DEFINED ON STREAMLINE ANALYSIS. AN AREA OF 73-75 DEW POINTS ACROSS EAST CENTRAL IL IS FEEDING INTO THIS AREA LEADING TO MLCAPES OF 3000-3500 J/KG. SIMILAR HERE...ISOLATED TO SCATTERED STORM DEVELOPMENT COULD BE SEEN...WITH SLOW MOVING CELLS IF ANYTHING CAN DEVELOP AS THE ACTIVITY IS FURTHER REMOVED FROM THE BETTER STEERING FLOW TO THE NORTH. OVERALL IT IS TRENDING THAT STORM CHANCES MAY BE BEST IN THE FORECAST AREA JUST AHEAD OF THE COOL FRONT WHICH AS OF 230 PM IS DRAPED FROM NORTHERN LAKE MI TO JUST SOUTH OF LA CROSSE WI. EVEN THEN THE COVERAGE COULD BE LIMITED. TOWERING CU HAS BEEN SEEN ALONG THIS AND THIS MAY FURTHER GROW AS THE FRONT UNDERCUTS THE AFOREMENTIONED DEEPER MOISTURE ALOFT BY LATE THIS AFTERNOON. SUBTLE SHORT WAVE ENERGY TRACKING EAST ACROSS NORTHERN IA COULD INTERACT WITH THIS TO HELP SPRING ACTIVITY...BUT IT MAY STRUGGLE LASTING DEEP INTO THE EVE AT LEAST WITH STRONG POTENTIAL GIVEN THE DIURNAL HEATING OF THE DAY HAVING WANED. CONVECTIVE ALLOWING GUIDANCE HAS QUITE A BIT OF RANGE IN SOLUTIONS...WHICH DOES NOT HELP TO BOLSTER CONFIDENCE ANY. LAPS AND RAP ANALYSIS AND SOUNDINGS INDICATE LARGE VALUES OF DCAPE /1100+ J/KG/ WHICH COMBINED WITH PRECIPITATION LOADING CONCERNS COULD FAVOR ISOLATED WET MICROBURSTS IN ANY STORMS...WHICH REMAINS THE PRIMARY CONCERN. DEEP LAYER SHEAR IS SLOWLY INCREASING JUST NOW APPROACHING 30 KT NEAR THE IL/WI BORDER...BUT IN GENERAL REMAINS WEAK ELSEWHERE. OBVIOUSLY THE HIGH PWATS CONTINUE TO SUPPORT HEAVY RAIN IN ANY STORM. MTF && .DISCUSSION... 316 PM CDT THE MAIN FORECAST CONCERNS WILL FIRST FOCUS ON CONVECTIVE TRENDS THIS EVENING AND OVERNIGHT...AND ALSO THE HEAT THROUGH THIS EVENING. HOWEVER...OTHER CONCERNS IN THE FORECAST PERIOD WILL BE ADDITIONAL THREATS OF CONVECTION/MCS`S LATER THIS WEEKEND INTO EARLY NEXT WEEK. A COLD FRONTAL BOUNDARY IS CURRENTLY DROPPING SOUTHWARD ACROSS SOUTHERN WISCONSIN. LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY HAS REMAINED FAIRLY WEAK AS A WELL MIXED WARM SECTOR HAS PRODUCED SOUTHWESTERLY FLOW RELATIVELY PARALLEL WITH THE SURFACE FRONT. AS A RESULT OF THIS...STORM DEVELOPMENT HAS REMAINED ISOLATED THUS FAR. IN SPITE OF THIS ADDITIONAL STORMS ARE STILL EXPECTED TO DEVELOP THROUGH THE AFTERNOON. FOR MORE INFO ON THESE STORMS REFERENCE THE MESO DISCUSSION ABOVE. THUNDERSTORMS WILL LIKELY BECOME HIGHER IN AERIAL COVERAGE EARLY THIS EVENING AS LOWER LEVEL MOISTURE CONVERGENCE INCREASES AHEAD THIS BOUNDARY. IT APPEARS THE FRONT WILL BE SLOW TO CLEAR NORTHERN ILLINOIS...POSSIBLY NOT PASSING SOUTH OF CHICAGO UNTIL AFTER 03 UTC THIS EVENING. THEREFORE...THUNDERSTORMS WILL BE POSSIBLY THROUGH AT LEAST EARLY TO MID EVENING ACROSS MUCH OF ILLINOIS. THERE WILL STILL BE A THREAT FOR STORMS TO PRODUCE MICROBURSTS WITH ISOLATED AREAS OF STRONG DAMAGING WINDS INTO THIS EVENING AS DOWNDRAFT CAPE WILL REMAIN IN EXCESS OF 1,000 J/KG. HOWEVER...THE OTHER THREAT WILL BE TORRENTIAL DOWNPOURS WITH THESE THUNDERSTORMS. THE RICH THETA-E AIR...WITH PWATS UP AROUND 2 INCHES WILL PROVIDE AMPLE CONDITIONS FOR VERY HEAVY RAINFALL FROM THESE STORMS. MY CONCERN IS THAT AS THE LOWER LEVEL CONVERGENCE INCREASES ALONG THE LOWER LEVEL FRONTAL ZONE...THAT SOME OF THESE STORMS COULD TRAIN...WITH A NEARLY EASTERLY CLOUD BEARING FLOW AROUND 25 KT EXPECTED...WHICH SHOULD BE NEARLY PARALLEL TO THE BOUNDARY. IT APPEARS THE MAIN THREAT FOR THIS WILL BE PRIMARILY SOUTH OF CHICAGO ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN ILLINOIS COUNTIES. I HAVE MAINTAINED THE HEAVY RAIN WORDING IN THESE AREAS...ESPECIALLY THIS EVENING. THESE STORMS COULD EASY DROP 1 TO 2 INCHES PER HOUR...AND IF THE STORMS TRAIN OVER THE SAME AREAS THERE COULD BE SOME LOCALIZED AREAS OF HIGH RAINFALL AMOUNTS. THIS WILL NEED TO BE WATCHED THIS EVENING. CONFIDENCE IN WIDESPREAD HYDRO CONCERNS IN LOW...THEREFORE NO HEADLINES ARE PLANNED. THE THREAT FOR THUNDERSTORMS WITH HEAVY RAIN COULD CONTINUE OVERNIGHT ACROSS MY FAR SOUTHERN COUNTIES AS IT APPEARS THE FRONTAL BOUNDARY WILL BE SLOW TO MOVE ACROSS THESE AREAS. HOWEVER...IT APPEARS THAT THE FRONT SHOULD CLEAR THE AREA BY EARLY SATURDAY MORNING...ENDING THE THREAT FOR STORMS. I WILL LEAVE THE HEAT HEADLINES AS IS...WITH AN ENDING TIME AT 00 UTC THIS EVENING. WITH THE DEW POINTS MIXING OUT INTO THE UPPER 60S THE HEAT INDEX HAS NOT BEEN MUCH ABOVE 100. SO ALTHOUGH THE FRONT WILL NOT MOVE THROUGH TILL TONIGHT...IT APPEARS THE BIG HEAT WILL BE OVER BY 00 UTC...WITH COOLER AND LESS HUMID AIR TO MOVE IN LATER TONIGHT. SATURDAY AND SUNDAY WILL BE COOLER...WITH HIGHS MAINLY IN THE LOW TO MID 80S...WITH AN ONSHORE FLOW. DRY CONDITIONS ARE EXPECTED FOR MUCH OF THE WEEKEND. HOWEVER...THE CHANCE FOR MORE STORMS WILL INCREASE LATE SUNDAY AND SUNDAY NIGHT AS ANOTHER DISTURBANCE APPROACHES THE AREA. IT CURRENTLY APPEARS THE MAIN FOCUS MAY BE ACROSS THE SOUTHERN HALF TO TWO THIRDS OF MY AREA...BUT THE POTENTIAL FOR SOME ADDITIONAL HEAVY RAIN AREA POSSIBLE INTO EARLY MONDAY. SUBSIDENCE IN THE WAKE OF THIS DISTURBANCE MAY LEAD TO LITTLE TO NO CONVECTIVE ACTIVITY MONDAY AFTERNOON AND NIGHT. I HAVE THEREFORE TRENDED POPS DOWN SIGNIFICANTLY FOR THIS TIMEFRAME. HOWEVER...A FAIRLY DISTURBED WEST-NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL CONUS WILL LIKELY DRIVE ANOTHER DISTURBANCE OR TWO ACROSS THE AREA ON TUESDAY. THIS WILL PRODUCE ANOTHER DECENT CHANCE OF THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. ONCE THIS DISTURBANCE MOVES THROUGH...THE FLOW ALOFT LOOKS TO AMPLIFY SOME...WITH BUILDING HEIGHTS ACROSS THE WESTERN CONUS. THIS SHOULD ALLOW A COLD FRONT AND AREA OF SURFACE HIGH PRESSURE TO SHIFT SOUTHWARD ACROSS THE GREAT LAKES REGION. THIS SHOULD RESULT IN THE MAIN THREAT FOR CONVECTIVE ACTIVITY SHIFTING SOUTH OF THE REGION FOR WEDNESDAY THROUGH THURSDAY...WITH A CONTINUATION OF COOL TEMPERATURES INTO LATER NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY SW WINDS BETWEEN 20-25KT WITH A FEW GUSTS TO 30 KT THRU EARLY THIS EVE. * ISO SHRA/TSRA DEVELOPING...BEST TIMING FOR STRONGER TSRA WOULD BE AFT 21Z THRU 01Z. * WIND DIR SHIFTING FROM WEST TO NORTH THIS EVENING. THEN WINDS STEADILY TURN NORTHEAST BY DAYBREAK SAT. SPEEDS TONIGHT THRU MIDDAY SAT WILL GENERALLY BE 7-10KT. BEACHLER //DISCUSSION...UPDATED 18Z... ATMOSPHERE OVER NORTHERN IL/NORTHWEST IN BEGINNING TO BECOME UNSTBALE AND PRIMED FOR ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST GUIDANCE CONTINUES TO FAVOR STEADILY INCREASED COVERAGE/INTENSITY OF THUNDERSTORMS BY 20-21Z. CUMULUS CLOUDS WILL THICKEN AND BUILD...AS THE CONVECTIVE POTENTIAL INCREASES. ALL OF THIS ACTIVITY WILL DEVELOP AHEAD OF THE FRONTAL BOUNDARY...WITH BREEZY CONDITIONS FROM THE SOUTHWEST. WINDS WILL GENERALLY BE THRU FRONTAL PASSAGE AND WITH PRECIP ARND 20-25KT. THEN BY 00-01Z TSRA COVERAGE WILL BEGIN TO DIMINISH AND SHIFT TO THE SOUTHEAST OF TAF SITES. EXPECT BY 02Z TSRA TO HAVE COME TO AN END WITH WINDS TURNING NORTH/NORTHEAST OVERNIGHT. THE GRADIENT BRIEFLY DIMINISHES LATE TONIGHT...WITH WINDS POSSIBLY COMING DOWN TO LESS THAN 7KT. SKIES WILL BECOME PARTLY CLOUDY WITH JUST A CIRRUS SHIELD OVERNIGHT. JUST AFT DAYBREAK SAT WIND SPEEDS WILL INCREASE TO 12-15KT WITH MOSTLY CLEAR SKIES...THEN EXPECT DIURNAL CUMULUS CLOUDS TO DEVELOP WITH BASES ARND 4KFT AGL...THIS SHUD HELP TO TRIM WINDS BACK TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM/HIGH CONFIDENCE IN SCT TSRA THIS AFTERNOON THRU EARLY EVENING. * MEDIUM CONFIDENCE IN TIMING OF ARRIVAL/ENDING AT ORD/MDW. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * HIGH CONFIDENCE IN WINDS TURNING NORTHEAST BY DAYBREAK SAT. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. WX NIL. SUNDAY...CHANCE OF TSRA AFTERNOON THROUGH OVERNIGHT. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES TSRA. THURSDAY...VFR. WX NIL. KREIN && .MARINE... 329 PM CDT INITIAL CONCERN IN THE NEARSHORE WITH GUSTY WEST-SOUTHWEST WINDS OCCASIONALLY TO 30 KT AHEAD OF A COLD FRONT. WITH SLOW PROGRESS OF FRONT...IT IS POSSIBLE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED FOR A FEW HOURS INTO MID EVENING. ALSO A FEW GUSTY STORMS ARE POSSIBLE THROUGH EARLY EVENING...WITH AN OUTSIDE CHANCE FOR GUSTS OVER 50 KT. THIS INCLUDES THE OPEN WATERS. BEHIND THE FRONT...A STRONG PUSH OF COOL AIR FOR THIS TIME OF YEAR WILL MOVE DOWN THE LAKE RESULTING IN INCREASING NORTHERLY WINDS...FIRST ON THE NORTH HALF SHIFTING TO THE SOUTH HALF DURING THE DAY SATURDAY. THERE MAY BE OCCASIONAL GUSTS TO 30 KT OVER THE OPEN WATERS. THEN HIGH PRESSURE WILL BUILD OVER THE LAKE BY SUNDAY AND WINDS WILL DIMINISH. THOUGH LOW PRESSURE WILL MOVE OVER THE REGION EARLY NEXT WEEK AND A COLD FRONT WILL PUSH ACROSS THE LAKE BY TUESDAY...WINDS LOOK TO REMAIN FAIRLY LIGHT OUT OF THE SOUTH UNTIL THE COLD FRONT PASSAGE. THEN AFTER THE FRONTAL PASSAGE LATE TUESDAY...THERE COULD POTENTIALLY BE A PERIOD OF MODESTLY STRONGER NORTHERLY WINDS FOLLOWED BY AN EXTENDED PERIOD OF LIGHT WINDS MID TO LATE NEXT WEEK AS HIGH PRESSURE SPREADS ACROSS THE GREAT LAKES. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 PM FRIDAY. IN...HEAT ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 PM FRIDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
317 PM CDT FRI JUL 19 2013 .MESOSCALE DISCUSSION... 239 PM CDT CONTINUING TO MONITOR CONVECTIVE CHANCES THIS AFTERNOON INTO EARLY EVENING WITH TRENDS SLOW TO GO THUS FAR AND CONTINUING TO APPEAR THAT ANY SEVERE THREAT WOULD BE ISOLATED IN COVERAGE. AS THE UPPER TROUGH CONTINUES TO DIG INTO THE FAR NORTHERN GREAT LAKES THIS AFTERNOON...A NARROW PLUME OF DEEPER MOISTURE IN ADVANCE AS SEEN ON WATER VAPOR HAS MOVED EAST INTO NORTHERN IL. THERE HAS BEEN ACCAS AND AGITATED CU WITHIN THIS STREAM...ALONG WITH SPORADIC ISOLATED SHOWERS ACROSS SOUTHERN WI AND NOW INTO NORTHERN BOONE COUNTY IL. SUBTLE PRE-FRONTAL SURFACE CONVERGENCE IS NOTED IN OBSERVATIONS UNDER THIS...BUT IT HAS BECOME PROGRESSIVELY LESS CONVERGENT AS THE BOUNDARY LAYER HAS BECOME WELL-MIXED. GIVEN THAT AN NO NOTICEABLE TRENDS ON SATELLITE OR RADAR DO NOT FORESEE ANY WIDESPREAD CONVECTIVE GROWTH ON THIS...ALTHOUGH ISOLATED TO SCATTERED STORMS COULD DEVELOP OR FESTER...PROBABLY MOST FAVORED ACROSS FAR NORTHEAST IL. FURTHER TO THE SOUTH A REMNANT ELEVATED OUTFLOW AS SEEN EARLIER ON SATELLITE AND RADAR HAS STALLED ACROSS FAR NORTHERN IN SOUTHWEST OVER KANKAKEE AND PONTIAC. THIS HAS TRIGGERED SOME CU WITH BETTER VERTICAL GROWTH ALONG WITH SHOWERS NOW BEING SEEN ALONG THE IN/MI BORDER WHERE CONVERGENCE APPEARS MORE DEFINED ON STREAMLINE ANALYSIS. AN AREA OF 73-75 DEW POINTS ACROSS EAST CENTRAL IL IS FEEDING INTO THIS AREA LEADING TO MLCAPES OF 3000-3500 J/KG. SIMILAR HERE...ISOLATED TO SCATTERED STORM DEVELOPMENT COULD BE SEEN...WITH SLOW MOVING CELLS IF ANYTHING CAN DEVELOP AS THE ACTIVITY IS FURTHER REMOVED FROM THE BETTER STEERING FLOW TO THE NORTH. OVERALL IT IS TRENDING THAT STORM CHANCES MAY BE BEST IN THE FORECAST AREA JUST AHEAD OF THE COOL FRONT WHICH AS OF 230 PM IS DRAPED FROM NORTHERN LAKE MI TO JUST SOUTH OF LA CROSSE WI. EVEN THEN THE COVERAGE COULD BE LIMITED. TOWERING CU HAS BEEN SEEN ALONG THIS AND THIS MAY FURTHER GROW AS THE FRONT UNDERCUTS THE AFOREMENTIONED DEEPER MOISTURE ALOFT BY LATE THIS AFTERNOON. SUBTLE SHORT WAVE ENERGY TRACKING EAST ACROSS NORTHERN IA COULD INTERACT WITH THIS TO HELP SPRING ACTIVITY...BUT IT MAY STRUGGLE LASTING DEEP INTO THE EVE AT LEAST WITH STRONG POTENTIAL GIVEN THE DIURNAL HEATING OF THE DAY HAVING WANED. CONVECTIVE ALLOWING GUIDANCE HAS QUITE A BIT OF RANGE IN SOLUTIONS...WHICH DOES NOT HELP TO BOLSTER CONFIDENCE ANY. LAPS AND RAP ANALYSIS AND SOUNDINGS INDICATE LARGE VALUES OF DCAPE /1100+ J/KG/ WHICH COMBINED WITH PRECIPITATION LOADING CONCERNS COULD FAVOR ISOLATED WET MICROBURSTS IN ANY STORMS...WHICH REMAINS THE PRIMARY CONCERN. DEEP LAYER SHEAR IS SLOWLY INCREASING JUST NOW APPROACHING 30 KT NEAR THE IL/WI BORDER...BUT IN GENERAL REMAINS WEAK ELSEWHERE. OBVIOUSLY THE HIGH PWATS CONTINUE TO SUPPORT HEAVY RAIN IN ANY STORM. MTF && .DISCUSSION... 316 PM CDT THE MAIN FORECAST CONCERNS WILL FIRST FOCUS ON CONVECTIVE TRENDS THIS EVENING AND OVERNIGHT...AND ALSO THE HEAT THROUGH THIS EVENING. HOWEVER...OTHER CONCERNS IN THE FORECAST PERIOD WILL BE ADDITIONAL THREATS OF CONVECTION/MCS`S LATER THIS WEEKEND INTO EARLY NEXT WEEK. A COLD FRONTAL BOUNDARY IS CURRENTLY DROPPING SOUTHWARD ACROSS SOUTHERN WISCONSIN. LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY HAS REMAINED FAIRLY WEAK AS A WELL MIXED WARM SECTOR HAS PRODUCED SOUTHWESTERLY FLOW RELATIVELY PARALLEL WITH THE SURFACE FRONT. AS A RESULT OF THIS...STORM DEVELOPMENT HAS REMAINED ISOLATED THUS FAR. IN SPITE OF THIS ADDITIONAL STORMS ARE STILL EXPECTED TO DEVELOP THROUGH THE AFTERNOON. FOR MORE INFO ON THESE STORMS REFERENCE THE MESO DISCUSSION ABOVE. THUNDERSTORMS WILL LIKELY BECOME HIGHER IN AERIAL COVERAGE EARLY THIS EVENING AS LOWER LEVEL MOISTURE CONVERGENCE INCREASES AHEAD THIS BOUNDARY. IT APPEARS THE FRONT WILL BE SLOW TO CLEAR NORTHERN ILLINOIS...POSSIBLY NOT PASSING SOUTH OF CHICAGO UNTIL AFTER 03 UTC THIS EVENING. THEREFORE...THUNDERSTORMS WILL BE POSSIBLY THROUGH AT LEAST EARLY TO MID EVENING ACROSS MUCH OF ILLINOIS. THERE WILL STILL BE A THREAT FOR STORMS TO PRODUCE MICROBURSTS WITH ISOLATED AREAS OF STRONG DAMAGING WINDS INTO THIS EVENING AS DOWNDRAFT CAPE WILL REMAIN IN EXCESS OF 1,000 J/KG. HOWEVER...THE OTHER THREAT WILL BE TORRENTIAL DOWNPOURS WITH THESE THUNDERSTORMS. THE RICH THETA-E AIR...WITH PWATS UP AROUND 2 INCHES WILL PROVIDE AMPLE CONDITIONS FOR VERY HEAVY RAINFALL FROM THESE STORMS. MY CONCERN IS THAT AS THE LOWER LEVEL CONVERGENCE INCREASES ALONG THE LOWER LEVEL FRONTAL ZONE...THAT SOME OF THESE STORMS COULD TRAIN...WITH A NEARLY EASTERLY CLOUD BEARING FLOW AROUND 25 KT EXPECTED...WHICH SHOULD BE NEARLY PARALLEL TO THE BOUNDARY. IT APPEARS THE MAIN THREAT FOR THIS WILL BE PRIMARILY SOUTH OF CHICAGO ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN ILLINOIS COUNTIES. I HAVE MAINTAINED THE HEAVY RAIN WORDING IN THESE AREAS...ESPECIALLY THIS EVENING. THESE STORMS COULD EASY DROP 1 TO 2 INCHES PER HOUR...AND IF THE STORMS TRAIN OVER THE SAME AREAS THERE COULD BE SOME LOCALIZED AREAS OF HIGH RAINFALL AMOUNTS. THIS WILL NEED TO BE WATCHED THIS EVENING. CONFIDENCE IN WIDESPREAD HYDRO CONCERNS IN LOW...THEREFORE NO HEADLINES ARE PLANNED. THE THREAT FOR THUNDERSTORMS WITH HEAVY RAIN COULD CONTINUE OVERNIGHT ACROSS MY FAR SOUTHERN COUNTIES AS IT APPEARS THE FRONTAL BOUNDARY WILL BE SLOW TO MOVE ACROSS THESE AREAS. HOWEVER...IT APPEARS THAT THE FRONT SHOULD CLEAR THE AREA BY EARLY SATURDAY MORNING...ENDING THE THREAT FOR STORMS. I WILL LEAVE THE HEAT HEADLINES AS IS...WITH AN ENDING TIME AT 00 UTC THIS EVENING. WITH THE DEW POINTS MIXING OUT INTO THE UPPER 60S THE HEAT INDEX HAS NOT BEEN MUCH ABOVE 100. SO ALTHOUGH THE FRONT WILL NOT MOVE THROUGH TILL TONIGHT...IT APPEARS THE BIG HEAT WILL BE OVER BY 00 UTC...WITH COOLER AND LESS HUMID AIR TO MOVE IN LATER TONIGHT. SATURDAY AND SUNDAY WILL BE COOLER...WITH HIGHS MAINLY IN THE LOW TO MID 80S...WITH AN ONSHORE FLOW. DRY CONDITIONS ARE EXPECTED FOR MUCH OF THE WEEKEND. HOWEVER...THE CHANCE FOR MORE STORMS WILL INCREASE LATE SUNDAY AND SUNDAY NIGHT AS ANOTHER DISTURBANCE APPROACHES THE AREA. IT CURRENTLY APPEARS THE MAIN FOCUS MAY BE ACROSS THE SOUTHERN HALF TO TWO THIRDS OF MY AREA...BUT THE POTENTIAL FOR SOME ADDITIONAL HEAVY RAIN AREA POSSIBLE INTO EARLY MONDAY. SUBSIDENCE IN THE WAKE OF THIS DISTURBANCE MAY LEAD TO LITTLE TO NO CONVECTIVE ACTIVITY MONDAY AFTERNOON AND NIGHT. I HAVE THEREFORE TRENDED POPS DOWN SIGNIFICANTLY FOR THIS TIMEFRAME. HOWEVER...A FAIRLY DISTURBED WEST-NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL CONUS WILL LIKELY DRIVE ANOTHER DISTURBANCE OR TWO ACROSS THE AREA ON TUESDAY. THIS WILL PRODUCE ANOTHER DECENT CHANCE OF THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. ONCE THIS DISTURBANCE MOVES THROUGH...THE FLOW ALOFT LOOKS TO AMPLIFY SOME...WITH BUILDING HEIGHTS ACROSS THE WESTERN CONUS. THIS SHOULD ALLOW A COLD FRONT AND AREA OF SURFACE HIGH PRESSURE TO SHIFT SOUTHWARD ACROSS THE GREAT LAKES REGION. THIS SHOULD RESULT IN THE MAIN THREAT FOR CONVECTIVE ACTIVITY SHIFTING SOUTH OF THE REGION FOR WEDNESDAY THROUGH THURSDAY...WITH A CONTINUATION OF COOL TEMPERATURES INTO LATER NEXT WEEK. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY SW WINDS BETWEEN 20-25KT WITH A FEW GUSTS TO 30 KT THRU EARLY THIS EVE. * ISO SHRA/TSRA DEVELOPING...BEST TIMING FOR STRONGER TSRA WOULD BE AFT 21Z THRU 01Z. * WIND DIR SHIFTING FROM WEST TO NORTH THIS EVENING. THEN WINDS STEADILY TURN NORTHEAST BY DAYBREAK SAT. SPEEDS TONIGHT THRU MIDDAY SAT WILL GENERALLY BE 7-10KT. BEACHLER //DISCUSSION...UPDATED 18Z... ATMOSPHERE OVER NORTHERN IL/NORTHWEST IN BEGINNING TO BECOME UNSTBALE AND PRIMED FOR ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST GUIDANCE CONTINUES TO FAVOR STEADILY INCREASED COVERAGE/INTENSITY OF THUNDERSTORMS BY 20-21Z. CUMULUS CLOUDS WILL THICKEN AND BUILD...AS THE CONVECTIVE POTENTIAL INCREASES. ALL OF THIS ACTIVITY WILL DEVELOP AHEAD OF THE FRONTAL BOUNDARY...WITH BREEZY CONDITIONS FROM THE SOUTHWEST. WINDS WILL GENERALLY BE THRU FRONTAL PASSAGE AND WITH PRECIP ARND 20-25KT. THEN BY 00-01Z TSRA COVERAGE WILL BEGIN TO DIMINISH AND SHIFT TO THE SOUTHEAST OF TAF SITES. EXPECT BY 02Z TSRA TO HAVE COME TO AN END WITH WINDS TURNING NORTH/NORTHEAST OVERNIGHT. THE GRADIENT BRIEFLY DIMINISHES LATE TONIGHT...WITH WINDS POSSIBLY COMING DOWN TO LESS THAN 7KT. SKIES WILL BECOME PARTLY CLOUDY WITH JUST A CIRRUS SHIELD OVERNIGHT. JUST AFT DAYBREAK SAT WIND SPEEDS WILL INCREASE TO 12-15KT WITH MOSTLY CLEAR SKIES...THEN EXPECT DIURNAL CUMULUS CLOUDS TO DEVELOP WITH BASES ARND 4KFT AGL...THIS SHUD HELP TO TRIM WINDS BACK TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM/HIGH CONFIDENCE IN SCT TSRA THIS AFTERNOON THRU EARLY EVENING. * MEDIUM CONFIDENCE IN TIMING OF ARRIVAL/ENDING AT ORD/MDW. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * HIGH CONFIDENCE IN WINDS TURNING NORTHEAST BY DAYBREAK SAT. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. WX NIL. SUNDAY...CHANCE OF TSRA AFTERNOON THROUGH OVERNIGHT. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES TSRA. THURSDAY...VFR. WX NIL. KREIN && .MARINE... 300 AM CDT A BROAD RIDGE OF HIGH PRESSURE EXTENDS FROM THE SOUTH HIGH PLAINS THROUGH THE OHIO VALLEY. THIS RIDGE WILL SAG SOUTHEAST AND STALL OUT OVER THE GULF COAST REGION LATE FRIDAY. MEANWHILE...LOW PRESSURE OVER JAMES BAY WILL DEEPEN SLIGHTLY AS IT TRACKS EAST TO NORTHERN QUEBEC...WHILE DRAGGING A COLD FRONT SOUTH ACROSS THE LAKE FRIDAY. SOUTHWEST WINDS WILL INCREASE TO AROUND 30KT OVER MUCH OF THE LAKE TODAY AS THE GRADIENT STRENGTHENS IN ADVACE OF THE COLD FRONT. WINDS WILL THEN SHIFT TO MORE NORTHERLY BEHIND THE FRONT...TEMPORARILY WEAKENING FOR A BRIEF PERIOD FRIDAY NIGHT. A SECONDARY SURGE OF COOLER AIR WILL PUSH DOWN THE LAKE LATE FRIDAY NIGHT AND SATURDAY STRENGTHENING THE WINDS TO AROUND 25KT WHILE VEERING THROUGH NORTHERLY TO NORTHEASTERLY. AS HIGH PRESSURE BUILDS FROM CENTRAL CANADA INTO THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES...WINDS WILL THEN VEER EASTERLY OVER THE LAKE...WHILE REMAINING RATHER BRISK. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 PM FRIDAY. IN...HEAT ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 PM FRIDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
240 PM CDT FRI JUL 19 2013 .MESOSCALE DISCUSSION... 239 PM CDT CONTINUING TO MONITOR CONVECTIVE CHANCES THIS AFTERNOON INTO EARLY EVENING WITH TRENDS SLOW TO GO THUS FAR AND CONTINUING TO APPEAR THAT ANY SEVERE THREAT WOULD BE ISOLATED IN COVERAGE. AS THE UPPER TROUGH CONTINUES TO DIG INTO THE FAR NORTHERN GREAT LAKES THIS AFTERNOON...A NARROW PLUME OF DEEPER MOISTURE IN ADVANCE AS SEEN ON WATER VAPOR HAS MOVED EAST INTO NORTHERN IL. THERE HAS BEEN ACCAS AND AGITATED CU WITHIN THIS STREAM...ALONG WITH SPORADIC ISOLATED SHOWERS ACROSS SOUTHERN WI AND NOW INTO NORTHERN BOONE COUNTY IL. SUBTLE PRE-FRONTAL SURFACE CONVERGENCE IS NOTED IN OBSERVATIONS UNDER THIS...BUT IT HAS BECOME PROGRESSIVELY LESS CONVERGENT AS THE BOUNDARY LAYER HAS BECOME WELL-MIXED. GIVEN THAT AN NO NOTICEABLE TRENDS ON SATELLITE OR RADAR DO NOT FORESEE ANY WIDESPREAD CONVECTIVE GROWTH ON THIS...ALTHOUGH ISOLATED TO SCATTERED STORMS COULD DEVELOP OR FESTER...PROBABLY MOST FAVORED ACROSS FAR NORTHEAST IL. FURTHER TO THE SOUTH A REMNANT ELEVATED OUTFLOW AS SEEN EARLIER ON SATELLITE AND RADAR HAS STALLED ACROSS FAR NORTHERN IN SOUTHWEST OVER KANKAKEE AND PONTIAC. THIS HAS TRIGGERED SOME CU WITH BETTER VERTICAL GROWTH ALONG WITH SHOWERS NOW BEING SEEN ALONG THE IN/MI BORDER WHERE CONVERGENCE APPEARS MORE DEFINED ON STREAMLINE ANALYSIS. AN AREA OF 73-75 DEW POINTS ACROSS EAST CENTRAL IL IS FEEDING INTO THIS AREA LEADING TO MLCAPES OF 3000-3500 J/KG. SIMILAR HERE...ISOLATED TO SCATTERED STORM DEVELOPMENT COULD BE SEEN...WITH SLOW MOVING CELLS IF ANYTHING CAN DEVELOP AS THE ACTIVITY IS FURTHER REMOVED FROM THE BETTER STEERING FLOW TO THE NORTH. OVERALL IT IS TRENDING THAT STORM CHANCES MAY BE BEST IN THE FORECAST AREA JUST AHEAD OF THE COOL FRONT WHICH AS OF 230 PM IS DRAPED FROM NORTHERN LAKE MI TO JUST SOUTH OF LA CROSSE WI. EVEN THEN THE COVERAGE COULD BE LIMITED. TOWERING CU HAS BEEN SEEN ALONG THIS AND THIS MAY FURTHER GROW AS THE FRONT UNDERCUTS THE AFOREMENTIONED DEEPER MOISTURE ALOFT BY LATE THIS AFTERNOON. SUBTLE SHORT WAVE ENERGY TRACKING EAST ACROSS NORTHERN IA COULD INTERACT WITH THIS TO HELP SPRING ACTIVITY...BUT IT MAY STRUGGLE LASTING DEEP INTO THE EVE AT LEAST WITH STRONG POTENTIAL GIVEN THE DIURNAL HEATING OF THE DAY HAVING WANED. CONVECTIVE ALLOWING GUIDANCE HAS QUITE A BIT OF RANGE IN SOLUTIONS...WHICH DOES NOT HELP TO BOLSTER CONFIDENCE ANY. LAPS AND RAP ANALYSIS AND SOUNDINGS INDICATE LARGE VALUES OF DCAPE /1100+ J/KG/ WHICH COMBINED WITH PRECIPITATION LOADING CONCERNS COULD FAVOR ISOLATED WET MICROBURSTS IN ANY STORMS...WHICH REMAINS THE PRIMARY CONCERN. DEEP LAYER SHEAR IS SLOWLY INCREASING JUST NOW APPROACHING 30 KT NEAR THE IL/WI BORDER...BUT IN GENERAL REMAINS WEAK ELSEWHERE. OBVIOUSLY THE HIGH PWATS CONTINUE TO SUPPORT HEAVY RAIN IN ANY STORM. MTF && .DISCUSSION... 1138 AM CDT THE MORNING CONVECTION AND THE ASSOCIATED CLOUD COVER HAVE DISSIPATED OVER THE PAST COUPLE HOURS ACROSS SOUTHERN WISCONSIN. IT APPEARS AN OUTFLOW BOUNDARY...LIKELY ELEVATED IS PUSHING ACROSS NORTHERN ILLINOIS AT THIS TIME. WITH SKIES REMAINING CLEAR ACROSS THE REGION...TEMPERATURES ARE QUICKLY WARMING INTO THE LOW 90S EARLY THIS MORNING. WITH EVEN WARM 925 MB TEMPERATURES TODAY NEAR 27 DEGREES C...PER 12 UTC DVN RAOB...I SEE NO REASON WHY TEMPERATURES WILL NOT WARM INTO THE MIDDLE 90S BY EARLY AFTERNOON. THEREFORE...I WARMED TEMPERATURES A FEW DEGREES. THE INCREASING SOUTHWESTERLY WINDS SHOULD HELP MIX OUT DEW POINTS SOME...RESULTING IN SOME SLIGHTLY LOWER DEW POINTS IN THE UPPER 60S TO THE LOW 70S. THEREFORE...HEAT INDEX VALUES STILL APPEAR TO PEAK NEAR 105 THIS AFTERNOON. IT APPEARS CONVECTION WILL FIRE UP ACROSS NORTHERN ILLINOIS AFTER 19 UTC. MODIFYING DVN 12 UTC RAOB FOR CURRENT CONDITIONS INDICATE VERY LITTLE CAP REMAINING ACROSS THE AREA WITH SB CAPE AROUND 2800 J/KG. THEREFORE...IT IS NOT SURPRISING THAT THE REGIONAL SATELLITE IMAGERY SHOWS AN AREA OF CLOUD COVER WITH INCREASING AGITATION ACROSS PORTIONS OF IOWA. THIS AREA ALSO COINCIDES WITH SOME ENHANCED BOUNDARY LAYER CONVERGENCE JUST AHEAD OF THE SURFACE COLD FRONT. THIS ACTIVITY SHOULD CONTINUE TO DEVELOP AND MOVE TOWARDS MY NORTHERN COUNTIES AFTER 19 OR 20 UTC AS THE SURFACE FRONT CONTINUES TO DROP SOUTHWARD. ADDITIONAL ISOLATED TO SCATTERED CONVECTION COULD ALSO DEVELOP FARTHER SOUTH AND EAST ACROSS THE SOUTHERN SUBURBS OF CHICAGO AND INTO NORTHWESTERN INDIANA THIS AFTERNOON...IN ASSOCIATION WITH INCREASING BOUNDARY LAYER CONVERGENCE ALONG A PREFRONTAL TROUGH. IT APPEARS THE MAIN SEVERE THREAT FROM THIS ACTIVITY WILL BE DAMAGING WIND GUSTS. DEEP LAYER SHEAR REMAINS RELATIVELY WEAK...20 TO 25 KT...MAINLY DUE TO THE STRONGER MID LEVEL FLOW REMAINING TO THE NORTH BEHIND THE FRONT. HOWEVER...WET OR EVEN HYBRID MICROBURSTS ARE LIKELY WITH THIS ACTIVITY WITH LAYER THETA-E DIFFERENCES IN EXCESS OF 20 DEGREES C. THE OTHER THREAT WILL BE THAT OF TORRENTIAL DOWNPOURS WITH THIS ACTIVITY. PWATS ARE PROGGED TO BY AROUND 2 INCHES...THEREFORE THESE STORMS WILL HAVE PLENTY OF HIGH THETA-E AIR TO WORK WITH. RAINFALL RATES IN SOME OF THESE STORMS COULD EASILY EXCEED AN INCH OR TWO AN HOUR...WHICH COULD RESULT IN SOME LOCALIZED HYDRO ISSUES...ESPECIALLY IF THIS OCCURS OVER THE URBAN AREAS. I DECIDED TO ADD HEAVY RAINFALL TO THE GRIDS EARLY THIS EVENING...BUT I KEPT IT SOUTH OF CHICAGO...MAINLY ACROSS EAST CENTRAL ILLINOIS AND NORTHWESTERN INDIANA WHERE THE CONVECTIVE ACTIVITY COULD LINGER THIS EVENING. STORM MOTIONS SHOULD BE TO THE EAST AROUND 25 KT...SO THE POTENTIAL FOR SOME TRAINING CELLS COULD RESULT IN LOCAL HEAVY RAINFALL AMOUNTS. KJB //PREV DISCUSSION... 337 AM CDT FORECAST CHALLENGES THIS MORNING INCLUDE HEAT AND THUNDERSTORMS CHANCES TODAY...FOLLOWED BY POPS/TSTORM CHANCES NEXT WEEK AS WE GET INTO A POTENTIALLY MORE UNSETTLED PATTERN AFTER A RETURN TO MORE SEASONABLE TEMPS THIS WEEKEND. TRICKY FORECAST FOR HEAT TODAY AS NORTHERN AND NORTHWESTERN PORTIONS OF THE CWA WILL SEE CONVECTIVE POTENTIAL RAMPING UP BY LATE MORNING WITH CLOUDINESS INCREASING. IN ADDITION...GOES SOUNDER PWAT IMAGERY SHOWS A SWATH OF LOWER PWAT AIR UPSTREAM AHEAD OF THE FRONT AND THIS WAS CONFIRMED IN 00Z SOUNDINGS WITH 925MB DEWPOINTS 5C+ LOWER THAN ILX/DVN. IN THIS REGION...STRONGER SOUTHWEST WINDS ALLOWED DEWPOINTS TO MIX OUT IN THE 60S THURS AFTERNOON AND AM CONCERNED WE COULD SEE SOMETHING SIMILAR HAPPEN HERE TODAY MAKING IT HARD FOR HEAT INDICES TO REACH 100F. RUC...WHICH DID SEEM TO INITIALIZE THIS DRIER AIR OK SHOWS IT GETTING PINCHED OFF THIS MORNING WITH NO APPRECIABLE DROP IN DEWPOINTS TODAY. IN REALITY...WE`RE PROBABLY TALKING ABOUT THE DIFFERENCE BETWEEN HEAT INDICES IN THE MID-UPPER 90S VS UP TO 100-105 WHICH IS PRETTY TRIVIAL DETAIL AT THIS POINT. NO SIGNIFICANT CHANGES WERE MADE TO FORECAST TEMPS OR HEAT INDICES...SO NO PLANS TO ALTER HEADLINES AT THIS TIME. CONVECTION HAS FINALLY BEGUN TO LIGHT UP DOWN THE FRONT OVER SOUTHERN MN WHICH GUIDANCE HAS BEEN SUGGESTING WOULD HAVE HAPPENED HOURS AGO. MANY OF THE CONVECTIVE ALLOWING MODELS (CAMS) HOLD ONTO THIS CONVECTION OR ITS OUTFLOW THROUGH THE MORNING WITH RE-INTENSIFICATION TAKING PLACE LATER THIS MORNING OVER SOUTHERN WI INTO N IL AS THE BOUNDARY LAYER RAPIDLY DESTABILIZES. GLANCING BLOW OF MID LEVEL HEIGHT FALLS ALONG WITH APPROACHING COLD FRONT AND STRONG INSTABILITY FAVOR SCATTERED TO POTENTIALLY NUMEROUS THUNDERSTORMS MOVING ACROSS THE AREA THIS AFTERNOON AND LINGERING INTO THIS EVENING SOUTH. CERTAINLY INSTABILITY WILL NOT BE LACKING...BUT GUIDANCE STRONGLY SUGGESTS THAT THE STRONGER FLOW ALOFT WILL LAG BEHIND THE FRONT AND CONVECTION TODAY WITH 0-6KM SHEAR MAGNITUDE OF GENERALLY LESS THAN 20KT. GIVEN THE WEAK SHEAR...VERY WARM TEMPS ALOFT (WET BULB ZERO RISING TO OVER 14KFT) AND WEAK MID LEVEL LAPSE RATES THE THREAT OF HAIL LOOKS MINIMAL. THE WEAK SHEAR ALSO SUGGESTS MINIMAL STORM SCALE ORGANIZATION OR LONGEVITY WITH ANY SEVERE THREAT LIKELY LIMITED TO SPOTTY PULSE TYPE MICROBURSTS WITH WHAT LIMITED SEVERE THREAT THERE IS LIKELY DIMINISHING FURTHER WITH SUNSET. NORTHERLY WINDS BEHIND THE FRONT LATER TONIGHT AND SATURDAY WILL GRADUALLY ADVECT IN LOWER DEWPOINTS AND COOLER TEMPERATURES...BUT AS IS TYPICAL WITH SUMMERTIME FRONT THE ARRIVAL OF THE COOLER/DRIER AIR WILL BE A GRADUAL PROCESS BEHIND THE FRONT. BY SUNDAY AND INTO THE FIRST HALF OF NEXT WEEK WITH A LOW AMPLITUDE WEST-NORTHWEST FLOW OVER THE REGION WITH MULTIPLE WEAK SHORTWAVES RIDING THIS FLOW INTO THE AREA BRINGING AT LEAST PERIODIC CHANCES OF SHOWERS AND THUNDERSTORMS. UNFORTUNATELY MODELS ARE ALL OVER THE PLACE IN TIMING AND INTENSITY OF THESE LOW AMPLITUDE FEATURES AND RESULTANT MCS ACTIVITY LENDING TO A LOW CONFIDENCE FORECAST. GIVEN THE LOW PREDICTABILITY OF THESE FEATURES WAS LEFT WITH LITTLE CHOICE THAN TO PAINT PERIOD AFTER PERIOD IN THE FORECAST WITH CHANCES POPS...WHEN IN REALITY MUCH OF THE PERIOD WILL BE DRY. TEMPERATURES GENERALLY LOOK TO BE FAIRLY SEASONABLE THROUGH THIS PERIOD...WITH DAYTIME TEMPS LIKELY AFFECTED TO A LARGE EXTENT BY COVERAGE OF PRECIP AND CLOUDINESS. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY SW WINDS BETWEEN 20-25KT WITH A FEW GUSTS TO 30 KT THRU EARLY THIS EVE. * ISO SHRA/TSRA DEVELOPING...BEST TIMING FOR STRONGER TSRA WOULD BE AFT 21Z THRU 01Z. * WIND DIR SHIFTING FROM WEST TO NORTH THIS EVENING. THEN WINDS STEADILY TURN NORTHEAST BY DAYBREAK SAT. SPEEDS TONIGHT THRU MIDDAY SAT WILL GENERALLY BE 7-10KT. BEACHLER //DISCUSSION...UPDATED 18Z... ATMOSPHERE OVER NORTHERN IL/NORTHWEST IN BEGINNING TO BECOME UNSTBALE AND PRIMED FOR ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST GUIDANCE CONTINUES TO FAVOR STEADILY INCREASED COVERAGE/INTENSITY OF THUNDERSTORMS BY 20-21Z. CUMULUS CLOUDS WILL THICKEN AND BUILD...AS THE CONVECTIVE POTENTIAL INCREASES. ALL OF THIS ACTIVITY WILL DEVELOP AHEAD OF THE FRONTAL BOUNDARY...WITH BREEZY CONDITIONS FROM THE SOUTHWEST. WINDS WILL GENERALLY BE THRU FRONTAL PASSAGE AND WITH PRECIP ARND 20-25KT. THEN BY 00-01Z TSRA COVERAGE WILL BEGIN TO DIMINISH AND SHIFT TO THE SOUTHEAST OF TAF SITES. EXPECT BY 02Z TSRA TO HAVE COME TO AN END WITH WINDS TURNING NORTH/NORTHEAST OVERNIGHT. THE GRADIENT BRIEFLY DIMINISHES LATE TONIGHT...WITH WINDS POSSIBLY COMING DOWN TO LESS THAN 7KT. SKIES WILL BECOME PARTLY CLOUDY WITH JUST A CIRRUS SHIELD OVERNIGHT. JUST AFT DAYBREAK SAT WIND SPEEDS WILL INCREASE TO 12-15KT WITH MOSTLY CLEAR SKIES...THEN EXPECT DIURNAL CUMULUS CLOUDS TO DEVELOP WITH BASES ARND 4KFT AGL...THIS SHUD HELP TO TRIM WINDS BACK TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM/HIGH CONFIDENCE IN SCT TSRA THIS AFTERNOON THRU EARLY EVENING. * MEDIUM CONFIDENCE IN TIMING OF ARRIVAL/ENDING AT ORD/MDW. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * HIGH CONFIDENCE IN WINDS TURNING NORTHEAST BY DAYBREAK SAT. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT...VFR. WX NIL. SUNDAY...CHANCE OF TSRA AFTERNOON THROUGH OVERNIGHT. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES TSRA. THURSDAY...VFR. WX NIL. KREIN && .MARINE... 300 AM CDT A BROAD RIDGE OF HIGH PRESSURE EXTENDS FROM THE SOUTH HIGH PLAINS THROUGH THE OHIO VALLEY. THIS RIDGE WILL SAG SOUTHEAST AND STALL OUT OVER THE GULF COAST REGION LATE FRIDAY. MEANWHILE...LOW PRESSURE OVER JAMES BAY WILL DEEPEN SLIGHTLY AS IT TRACKS EAST TO NORTHERN QUEBEC...WHILE DRAGGING A COLD FRONT SOUTH ACROSS THE LAKE FRIDAY. SOUTHWEST WINDS WILL INCREASE TO AROUND 30KT OVER MUCH OF THE LAKE TODAY AS THE GRADIENT STRENGTHENS IN ADVACE OF THE COLD FRONT. WINDS WILL THEN SHIFT TO MORE NORTHERLY BEHIND THE FRONT...TEMPORARILY WEAKENING FOR A BRIEF PERIOD FRIDAY NIGHT. A SECONDARY SURGE OF COOLER AIR WILL PUSH DOWN THE LAKE LATE FRIDAY NIGHT AND SATURDAY STRENGTHENING THE WINDS TO AROUND 25KT WHILE VEERING THROUGH NORTHERLY TO NORTHEASTERLY. AS HIGH PRESSURE BUILDS FROM CENTRAL CANADA INTO THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES...WINDS WILL THEN VEER EASTERLY OVER THE LAKE...WHILE REMAINING RATHER BRISK. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 PM FRIDAY. IN...HEAT ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 PM FRIDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1237 PM CDT FRI JUL 19 2013 ...UPDATE TO AVIATION... .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI JUL 19 2013 EARLY THIS MORNING A BROAD UPPER LEVEL RIDGE AXIS EXTENDED FROM COAST TO COAST ACROSS THE SOUTHERN CONUS. A CUT OFF UPPER LOW WAS DRIFTING WEST ACROSS THE NORTHERN GULF OF MEXICO. A SECOND CUT OFF LOW WAS DRIFTING SOUTHWEST INTO NORTHWEST MEXICO. AN UPPER LEVEL TROUGH WAS MOVING EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. TODAY AND TONIGHT...THE UPPER RIDGE ACROSS THE WESTERN CONUS WILL AMPLIFY CAUSING THE FLOW ACROSS THE CENTRAL PLAINS TO BECOME SLIGHTLY MORE NORTHWESTERLY. THE BEST UPPER LEVEL ASCENT AHEAD OF THE H5 TROUGH MOVING ACROSS THE NORTHERN PLAINS WILL REMAIN WELL NORTHEAST OF THE CWA. A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE INTO THE NORTHERN COUNTIES OF THE CWA BY 21Z. CONVERGENCE ALONG THIS FRONT MAY CAUSE ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE NORTHERN COUNTIES OF THE CWA. THE 00Z GFS AND TWO MESOSCALE MODELS...THE RAP AND NON-HYDROSTATIC WRF ARE SHOWING A LINE OF SCATTERED TO NUMEROUS SHOWERS DEVELOPING AHEAD OF THE FRONT AND PUSHING SOUTHEAST ACROSS THE REMAINDER OF THE CWA THROUGH THE EVENING HOURS. WHILE THE ECMWF AND 00Z NAM SHOW ONLY ISOLATED SHOWERS DEVELOPING ACROSS THE NORTHERN HALF OF THE CWA LATE FRIDAY AFTERNOON AND EVENING. I`M LEANING MORE TOWARDS THE NAM AND ECMWF SINCE THERE WILL BE LITTLE IN THE WAY OF UPPER LEVEL SUPPORT SINCE THE MAIN H5 TROUGH WILL BE DIGGING SOUTHEAST ACROSS THE MIDWEST INTO THE GREAT LAKES STATES. ATTM...I`LL KEEP THE LOW CHANCE POPS OF 25 TO 35 PERCENT ACROSS MUCH OF THE CWA TONIGHT. THE PRECIP SHOULD END FROM NORTH TO SOUTH DURING THE EARLY MORNING HOURS OF SATURDAY AS THE COLD FRONT PUSHES SOUTH OF THE CWA BY 12Z SAT. SKIES WILL START OUT MOSTLY SUNNY ACROSS THE CWA WITH AN INCREASE IN CU DURING THE AFTERNOON HOURS. HIGHS WILL REACH THE MID TO UPPER 90S ACROSS THE CWA. SURFACE DEWPOINTS WILL DECREASE SLIGHTLY DURING THE AFTERNOON HOURS AS THE BOUNDARY LAYER MIXES DEEPER ACROSS THE PLAINS. I HAVE AFTERNOON DEWPOINTS IN THE LOWER TO MID 60S...WHICH SHOULD KEEP HEAT INDICES NEAR THE HIGH TEMPERATURES IN THE UPPER 90S. HEAT INDICES MAY REACH AROUND 100 DEGREES ACROSS THE EASTERN COUNTIES OF THE CWA. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI JUL 19 2013 THE FRONT OR ITS REMNANTS WILL LIKELY REMAIN IN THE AREA THROUGH EARLY NEXT WEEK. WITH WEST TO NORTHWEST FLOW ALOFT ALSO DOMINATING...A SERIES OF SHORTWAVE TROUGHS WILL MOVE THROUGH THE FLOW AND ACROSS THE COUNTY WARNING AREA THROUGH THE EXTENDED PERIODS...ALTHOUGH THE MODELS OFFER DIFFERENT SOLUTIONS ON THE STRENGTH AND TIMING OF THESE SHORTWAVE TROUGHS. ALTHOUGH WILL GO WITH POPS THROUGH MOST OF THE FORECAST...THE BETTER CHANCES FOR MORE ORGANIZED/HIGHER COVERAGE CONVECTIVE EVENTS OCCURS DURING TWO PERIODS. THE FIRST WILL BE WITH A POSSIBLE MCS LATE SATURDAY NIGHT/EARLY SUNDAY ACROSS MAINLY THE WESTERN CWA AND WITH THE PASSAGE OF THE SHORTWAVE TROUGH ON THE NOSE OF VEERING LLVL FLOW AND STRONGER WARM ADVECTION LATE SUNDAY INTO SUNDAY NIGHT. THIS SHOULD BE FOLLOWED BY A PERIOD OF LOWER POP CHANCES INTO TUESDAY BEFORE ANOTHER SHORTWAVE TROUGH PASSES AND FRONT MOVES THROUGH THE AREA WITHIN ANOTHER REGION OF STRONGER WAA ALONG THE EASTERN PERIPHERY OF A STRONG THERMAL AXIS. WITH BOUNDARY STILL IN THE AREA/OR JUST SOUTH...WILL KEEP LOW POPS GOING PORTIONS OF THE CWA ON INTO THURSDAY HOWEVER. TEMPERATURES OVER THE WEEKEND INTO NEXT WEEK WILL BE CHALLENGING AS THE COUNTY WARNING AREA WILL OFTEN BE ON THE EASTERN EDGE OF A STRONG LLVL THERMAL AXIS WITH THE LLVL FLOW FREQUENTLY VEERED. HOWEVER...CLOUDS AND PERIODIC PRECIP CHANCES WILL BE OFFSETTING FACTORS. FOR NOW...HIGHS WILL GENERALLY BE IN THE LOW TO MID 90S THROUGH THE FCST. MONDAY AND TUESDAY WILL LIKELY BE THE WARMEST DAYS WITH SOME UPPER 90S POSSIBLE IN THE WESTERN/SOUTHWEST CWA. AT THIS POINT HEAT INDICES ON BOTH OF THOSE DAYS SHOULD BE IN THE 98 TO 102 DEGREE RANGE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1215 PM CDT FRI JUL 19 2013 VFR CONDITIONS AT KTOP/KFOE/KMHK FOR THE NEXT FORECAST PERIOD. A GRADUAL FROPA LATE THIS AFTERNOON MAINLY AFTER 22Z WILL VEER WINDS TO THE WEST AND THEN NORTHWEST BY 05Z AT KTOP/KFOE AND KMHK BY 04Z. TIMING IS APPROXIMATE AS MODELS VARY SLIGHTLY ON THE SPEED OF THE FRONT. WIDELY SCATTERED TSRA MAY BE POSSIBLE NEAR AND ALONG THE FRONT AS IT PASSES. INSERTED VCTS FOR THIS AFTERNOON/EARLY EVENING AT KMHK AND AFT 00Z AT KTOP/KFOE AS COVERAGE OF TSRA IS LOW. EXPECT LIGHT AND VARIABLE WINDS AFT 04Z AT TERMINALS WITH A BKN LAYER OF CIRRUS LINGERING THROUGH 18Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...BOWEN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
500 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI JUL 19 2013 EARLY THIS MORNING A BROAD UPPER LEVEL RIDGE AXIS EXTENDED FROM COAST TO COAST ACROSS THE SOUTHERN CONUS. A CUT OFF UPPER LOW WAS DRIFTING WEST ACROSS THE NORTHERN GULF OF MEXICO. A SECOND CUT OFF LOW WAS DRIFTING SOUTHWEST INTO NORTHWEST MEXICO. AN UPPER LEVEL TROUGH WAS MOVING EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. TODAY AND TONIGHT...THE UPPER RIDGE ACROSS THE WESTERN CONUS WILL AMPLIFY CAUSING THE FLOW ACROSS THE CENTRAL PLAINS TO BECOME SLIGHTLY MORE NORTHWESTERLY. THE BEST UPPER LEVEL ASCENT AHEAD OF THE H5 TROUGH MOVING ACROSS THE NORTHERN PLAINS WILL REMAIN WELL NORTHEAST OF THE CWA. A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE INTO THE NORTHERN COUNTIES OF THE CWA BY 21Z. CONVERGENCE ALONG THIS FRONT MAY CAUSE ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE NORTHERN COUNTIES OF THE CWA. THE 00Z GFS AND TWO MESOSCALE MODELS...THE RAP AND NON-HYDROSTATIC WRF ARE SHOWING A LINE OF SCATTERED TO NUMEROUS SHOWERS DEVELOPING AHEAD OF THE FRONT AND PUSHING SOUTHEAST ACROSS THE REMAINDER OF THE CWA THROUGH THE EVENING HOURS. WHILE THE ECMWF AND 00Z NAM SHOW ONLY ISOLATED SHOWERS DEVELOPING ACROSS THE NORTHERN HALF OF THE CWA LATE FRIDAY AFTERNOON AND EVENING. I`M LEANING MORE TOWARDS THE NAM AND ECMWF SINCE THERE WILL BE LITTLE IN THE WAY OF UPPER LEVEL SUPPORT SINCE THE MAIN H5 TROUGH WILL BE DIGGING SOUTHEAST ACROSS THE MIDWEST INTO THE GREAT LAKES STATES. ATTM...I`LL KEEP THE LOW CHANCE POPS OF 25 TO 35 PERCENT ACROSS MUCH OF THE CWA TONIGHT. THE PRECIP SHOULD END FROM NORTH TO SOUTH DURING THE EARLY MORNING HOURS OF SATURDAY AS THE COLD FRONT PUSHES SOUTH OF THE CWA BY 12Z SAT. SKIES WILL START OUT MOSTLY SUNNY ACROSS THE CWA WITH AN INCREASE IN CU DURING THE AFTERNOON HOURS. HIGHS WILL REACH THE MID TO UPPER 90S ACROSS THE CWA. SURFACE DEWPOINTS WILL DECREASE SLIGHTLY DURING THE AFTERNOON HOURS AS THE BOUNDARY LAYER MIXES DEEPER ACROSS THE PLAINS. I HAVE AFTERNOON DEWPOINTS IN THE LOWER TO MID 60S...WHICH SHOULD KEEP HEAT INDICES NEAR THE HIGH TEMPERATURES IN THE UPPER 90S. HEAT INDICES MAY REACH AROUND 100 DEGREES ACROSS THE EASTERN COUNTIES OF THE CWA. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI JUL 19 2013 THE FRONT OR ITS REMNANTS WILL LIKELY REMAIN IN THE AREA THROUGH EARLY NEXT WEEK. WITH WEST TO NORTHWEST FLOW ALOFT ALSO DOMINATING...A SERIES OF SHORTWAVE TROUGHS WILL MOVE THROUGH THE FLOW AND ACROSS THE COUNTY WARNING AREA THROUGH THE EXTENDED PERIODS...ALTHOUGH THE MODELS OFFER DIFFERENT SOLUTIONS ON THE STRENGTH AND TIMING OF THESE SHORTWAVE TROUGHS. ALTHOUGH WILL GO WITH POPS THROUGH MOST OF THE FORECAST...THE BETTER CHANCES FOR MORE ORGANIZED/HIGHER COVERAGE CONVECTIVE EVENTS OCCURS DURING TWO PERIODS. THE FIRST WILL BE WITH A POSSIBLE MCS LATE SATURDAY NIGHT/EARLY SUNDAY ACROSS MAINLY THE WESTERN CWA AND WITH THE PASSAGE OF THE SHORTWAVE TROUGH ON THE NOSE OF VEERING LLVL FLOW AND STRONGER WARM ADVECTION LATE SUNDAY INTO SUNDAY NIGHT. THIS SHOULD BE FOLLOWED BY A PERIOD OF LOWER POP CHANCES INTO TUESDAY BEFORE ANOTHER SHORTWAVE TROUGH PASSES AND FRONT MOVES THROUGH THE AREA WITHIN ANOTHER REGION OF STRONGER WAA ALONG THE EASTERN PERIPHERY OF A STRONG THERMAL AXIS. WITH BOUNDARY STILL IN THE AREA/OR JUST SOUTH...WILL KEEP LOW POPS GOING PORTIONS OF THE CWA ON INTO THURSDAY HOWEVER. TEMPERATURES OVER THE WEEKEND INTO NEXT WEEK WILL BE CHALLENGING AS THE COUNTY WARNING AREA WILL OFTEN BE ON THE EASTERN EDGE OF A STRONG LLVL THERMAL AXIS WITH THE LLVL FLOW FREQUENTLY VEERED. HOWEVER...CLOUDS AND PERIODIC PRECIP CHANCES WILL BE OFFSETTING FACTORS. FOR NOW...HIGHS WILL GENERALLY BE IN THE LOW TO MID 90S THROUGH THE FCST. MONDAY AND TUESDAY WILL LIKELY BE THE WARMEST DAYS WITH SOME UPPER 90S POSSIBLE IN THE WESTERN/SOUTHWEST CWA. AT THIS POINT HEAT INDICES ON BOTH OF THOSE DAYS SHOULD BE IN THE 98 TO 102 DEGREE RANGE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 454 AM CDT FRI JUL 19 2013 EXPECT VFR CONDITIONS THROUGH MOST OF THE NEXT 24 HOURS. THERE MAY BE SOME ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ACROSS THE TAF SITES. THERE CONTINUES TO BE UNCERTAINTY IN BOTH TIMING AND COVERAGE OF ANY THUNDERSTORM DEVELOPMENT AT THE TAF SITES THIS EVENING. THEREFORE...I DID NOT INCLUDE A VCTS IN THE TAFS. ANY THUNDERSTORMS MAY BRING BRIEF MVFR CEILINGS AND VISIBILITIES TO THE TAF SITES THIS EVENING. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...GARGAN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
358 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT FRI JUL 19 2013 EARLY THIS MORNING A BROAD UPPER LEVEL RIDGE AXIS EXTENDED FROM COAST TO COAST ACROSS THE SOUTHERN CONUS. A CUT OFF UPPER LOW WAS DRIFTING WEST ACROSS THE NORTHERN GULF OF MEXICO. A SECOND CUT OFF LOW WAS DRIFTING SOUTHWEST INTO NORTHWEST MEXICO. AN UPPER LEVEL TROUGH WAS MOVING EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. TODAY AND TONIGHT...THE UPPER RIDGE ACROSS THE WESTERN CONUS WILL AMPLIFY CAUSING THE FLOW ACROSS THE CENTRAL PLAINS TO BECOME SLIGHTLY MORE NORTHWESTERLY. THE BEST UPPER LEVEL ASCENT AHEAD OF THE H5 TROUGH MOVING ACROSS THE NORTHERN PLAINS WILL REMAIN WELL NORTHEAST OF THE CWA. A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE INTO THE NORTHERN COUNTIES OF THE CWA BY 21Z. CONVERGENCE ALONG THIS FRONT MAY CAUSE ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE NORTHERN COUNTIES OF THE CWA. THE 00Z GFS AND TWO MESOSCALE MODELS...THE RAP AND NON-HYDROSTATIC WRF ARE SHOWING A LINE OF SCATTERED TO NUMEROUS SHOWERS DEVELOPING AHEAD OF THE FRONT AND PUSHING SOUTHEAST ACROSS THE REMAINDER OF THE CWA THROUGH THE EVENING HOURS. WHILE THE ECMWF AND 00Z NAM SHOW ONLY ISOLATED SHOWERS DEVELOPING ACROSS THE NORTHERN HALF OF THE CWA LATE FRIDAY AFTERNOON AND EVENING. I`M LEANING MORE TOWARDS THE NAM AND ECMWF SINCE THERE WILL BE LITTLE IN THE WAY OF UPPER LEVEL SUPPORT SINCE THE MAIN H5 TROUGH WILL BE DIGGING SOUTHEAST ACROSS THE MIDWEST INTO THE GREAT LAKES STATES. ATTM...I`LL KEEP THE LOW CHANCE POPS OF 25 TO 35 PERCENT ACROSS MUCH OF THE CWA TONIGHT. THE PRECIP SHOULD END FROM NORTH TO SOUTH DURING THE EARLY MORNING HOURS OF SATURDAY AS THE COLD FRONT PUSHES SOUTH OF THE CWA BY 12Z SAT. SKIES WILL START OUT MOSTLY SUNNY ACROSS THE CWA WITH AN INCREASE IN CU DURING THE AFTERNOON HOURS. HIGHS WILL REACH THE MID TO UPPER 90S ACROSS THE CWA. SURFACE DEWPOINTS WILL DECREASE SLIGHTLY DURING THE AFTERNOON HOURS AS THE BOUNDARY LAYER MIXES DEEPER ACROSS THE PLAINS. I HAVE AFTERNOON DEWPOINTS IN THE LOWER TO MID 60S...WHICH SHOULD KEEP HEAT INDICES NEAR THE HIGH TEMPERATURES IN THE UPPER 90S. HEAT INDICES MAY REACH AROUND 100 DEGREES ACROSS THE EASTERN COUNTIES OF THE CWA. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 356 AM CDT FRI JUL 19 2013 THE FRONT OR ITS REMNANTS WILL LIKELY REMAIN IN THE AREA THROUGH EARLY NEXT WEEK. WITH WEST TO NORTHWEST FLOW ALOFT ALSO DOMINATING...A SERIES OF SHORTWAVE TROUGHS WILL MOVE THROUGH THE FLOW AND ACROSS THE COUNTY WARNING AREA THROUGH THE EXTENDED PERIODS...ALTHOUGH THE MODELS OFFER DIFFERENT SOLUTIONS ON THE STRENGTH AND TIMING OF THESE SHORTWAVE TROUGHS. ALTHOUGH WILL GO WITH POPS THROUGH MOST OF THE FORECAST...THE BETTER CHANCES FOR MORE ORGANIZED/HIGHER COVERAGE CONVECTIVE EVENTS OCCURS DURING TWO PERIODS. THE FIRST WILL BE WITH A POSSIBLE MCS LATE SATURDAY NIGHT/EARLY SUNDAY ACROSS MAINLY THE WESTERN CWA AND WITH THE PASSAGE OF THE SHORTWAVE TROUGH ON THE NOSE OF VEERING LLVL FLOW AND STRONGER WARM ADVECTION LATE SUNDAY INTO SUNDAY NIGHT. THIS SHOULD BE FOLLOWED BY A PERIOD OF LOWER POP CHANCES INTO TUESDAY BEFORE ANOTHER SHORTWAVE TROUGH PASSES AND FRONT MOVES THROUGH THE AREA WITHIN ANOTHER REGION OF STRONGER WAA ALONG THE EASTERN PERIPHERY OF A STRONG THERMAL AXIS. WITH BOUNDARY STILL IN THE AREA/OR JUST SOUTH...WILL KEEP LOW POPS GOING PORTIONS OF THE CWA ON INTO THURSDAY HOWEVER. TEMPERATURES OVER THE WEEKEND INTO NEXT WEEK WILL BE CHALLENGING AS THE COUNTY WARNING AREA WILL OFTEN BE ON THE EASTERN EDGE OF A STRONG LLVL THERMAL AXIS WITH THE LLVL FLOW FREQUENTLY VEERED. HOWEVER...CLOUDS AND PERIODIC PRECIP CHANCES WILL BE OFFSETTING FACTORS. FOR NOW...HIGHS WILL GENERALLY BE IN THE LOW TO MID 90S THROUGH THE FCST. MONDAY AND TUESDAY WILL LIKELY BE THE WARMEST DAYS WITH SOME UPPER 90S POSSIBLE IN THE WESTERN/SOUTHWEST CWA. AT THIS POINT HEAT INDICES ON BOTH OF THOSE DAYS SHOULD BE IN THE 98 TO 102 DEGREE RANGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1156 PM CDT THU JUL 18 2013 EXPECTING VFR CONDITIONS THROUGH THE AVIATION FORECAST PERIOD. A VERY WEAK BOUNDARY WILL SLIDE SOUTHWARD INTO NORTHERN KANSAS LATE IN THE TAF PERIOD...HOWEVER IT IS UNLIKELY THAT IT WILL REACH THE TERMINALS. WINDS MAY BECOME VERY LIGHT AND VARIABLE AS THE BOUNDARY APPROACHES. EXPECT A FEW THUNDERSTORMS ALONG OR JUST NORTH OF THE BOUNDARY...HOWEVER THESE STORMS SHOULD REMAIN NORTH OF THE TERMINALS UNTIL AFTER THIS FORECAST ISSUANCE. JL && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...LEIGHTON
AREA FORECAST DISCUSSION
NWS GOODLAND KS
212 AM MDT FRI JUL 19 2013 .UPDATE... ISSUED AT 1105 PM MDT THU JUL 18 2013 CONVECTION OVER PHILLIPS AND LOGAN COUNTIES IN COLORADO IS HAVING A DIFFICULT TIME MOVING INTO YUMA COUNTY. WILL KEEP A MENTION OF SOME STORMS THROUGH THE NIGHT THERE GIVEN SOME LOW LEVEL MOISTYRE CONVERGENCE...THOUGH THE HRRR MODEL NEVER BRINGS PRECIPITATION TO THE COUNTY THROUGH 12Z. SURFACE TROUGH HAS MOVED THROUGH FLAGLER AND YUMA...AND WILL ADJUST WIND DIRECTIONS OVER THE WESTERN HALF OF THE FORECAST AREA. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 228 PM MDT THU JUL 18 2013 AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE CLEAR. TEMPERATURES HAVE RISEN INTO THE MID 80S TO LOW 90S. GUSTY SOUTH WINDS CONTINUE THIS AFTERNOON DUE TO A LEE TROUGH OVER CENTRAL COLORADO AND A HIGH PRESSURE LOCATED TO THE SOUTH. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE ROCKIES THIS AFTERNOON. A COLD FRONT WAS LOCATED TO THE NORTH...IN THE VICINITY OF THE SOUTH DAKOTA AND NEBRASKA BORDER AND INTO SOUTHWEST WYOMING. FOR TONIGHT...MODELS INDICATE THAT SOME OF THE SHOWERS AND STORMS WILL MOVE TO THE EAST OFF THE TERRAIN. UNFORTUNATELY...MODELS SEEM PRETTY CONSISTENT IN SHOWING THAT ALL OF THE ACTIVITY WILL DIMINISH BEFORE MOVING INTO THE REGION. THE WEAK COLD FRONT WILL CONTINUE MOVING TO THE SOUTH TONIGHT...ENTERING THE REGION AROUND MIDNIGHT WITH A SLOW MOVEMENT TO THE SOUTH THROUGH THE OVERNIGHT HOURS. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT TONIGHT...MAINLY IN SOUTHWEST NEBRASKA AND NORTHEAST COLORADO. LOW TEMPERATURES TONIGHT SHOULD FALL INTO THE LOW TO UPPER 60S WITH COOLEST TEMPERATURES EXPECTED OVER EAST COLORADO. GUSTY SOUTH WINDS WILL DIMINISH THIS EVENING AS THE PRESSURE GRADIENT RELAXES. A PERIOD OF CALM WINDS IS ANTICIPATED JUST AHEAD OF THE COLD FRONT BEFORE NORTH TO NORTHEAST WINDS OF 5 TO 15 MPH BEGIN IN THE MORNING HOURS. FOR TOMORROW...THE WEAK COLD FRONT WILL CONTINUE A SLUGGISH SOUTHWARD PUSH. HIGHER DEWPOINTS THAN PREVIOUS DAYS ARE EXPECTED TO POOL ALONG AND JUST AHEAD OF THE FRONT. WITH THE INCREASED MOISTURE AND HIGH TEMPERATURES CLIMBING INTO THE LOW TO MID 90S AHEAD OF THE FRONT...INSTABILITY AND FRONTAL SURFACE CONVERGENCE SHOULD BE ENOUGH FOR SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP. EVEN THOUGH INSTABILITY WOULD BE ENOUGH TO SUPPORT SOME POSSIBLE SEVERE THUNDERSTORMS...WEAK LAPSE RATES AND LITTLE SHEAR LEAD ONE TO THINK THAT WIDESPREAD SEVERE WEATHER IS NOT LIKELY. A STRONG STORM OR TWO IS POSSIBLE BUT THAT SHOULD BE ABOUT IT. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES AND SLOW STORM MOTIONS...HEAVY DOWNPOURS SEEM LIKE A GOOD BET FOR THE STRONGER THUNDERSTORMS. WINDS WILL SHIFT TO THE EAST BEHIND THE WEAK COLD FRONT. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 212 AM MDT FRI JUL 19 2013 GFS HAS TRENDED SLIGHTLY MORE AMPLIFIED AND LESS PROGRESSIVE WITH THE UPPER LEVEL RIDGE IN THE WEST. THIS KEEPS OUR AREA IN NORTHWESTERLY FLOW ALOFT WITH EMBEDDED WEAK AND DIFFICULT TO RESOLVE SHORTWAVES RESULTING IN SOME CONVECTION TUESDAY THROUGH THURSDAY. IN CONTRAST...ECMWF HAS BEEN CONSISTENT WITH EXPANDING THE UPPER RIDGE FURTHER EAST AND HAS MORE DRAMATIC 500 MB HEIGHT RISES THE MIDDLE OF NEXT WEEK...LEADING TO SOME UNCERTAINTY. THE MOST PRONOUNCED SHORTWAVE IN NORTHWESTERLY FLOW ALOFT IS SHOWN BY BOTH GFS AND ECMWF AND WILL PASS THROUGH LATE TUESDAY. GFS IS STRONGEST WITH DEPICTING AN ASSOCIATED SURFACE BOUNDARY THAT MOVES INTO THE FORECAST AREA TUESDAY EVENING. ADDITIONALLY...COLUMN MOISTURE INCREASES WITH PWAT VALUES REACHING NEAR 1.5 INCHES. THIS IS A CHANGE FROM THE PREVIOUS FORECAST AND HAS REQUIRED THE INTRODUCTION OF SLIGHT CHANCE POP FOR TUESDAY EVENING/OVERNIGHT. ACCEPTED CR INITIAL TEMPERATURE GRIDS WHICH ARE A REASONABLY GOOD COMPROMISE BETWEEN THE COOLER MEX MOS MID WEEK AND THE HOTTER PATTERN THAT ECMWF IS SHOWING. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1105 PM MDT THU JUL 18 2013 SURFACE TROUGH WILL MOVE EAST THROUGH EASTERN COLORADO...AND WILL REACH KGLD AROUND 09Z. THIS WILL SWITCH THE SURFACE WINDS TO THE WEST. EXPECT WIND SHIFT AT KMCK AROUND 12Z. VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD...BUT EXPECT CONVECTION TO DEVELOP AFTER 18Z. THERE WILL BE CHANCE OF THUNDERSTORMS AT BOTH KGLD/KMCK...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INDICATE STORMS IN THE TAFS. IF STORMS DO MOVE OVER THE SITES...VISIBILITIES WILL DROP TO MVFR OR LOWER IN BRIEF HEAVY RAIN. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...MENTZER SHORT TERM...RRH LONG TERM...BRB AVIATION...MENTZER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1105 PM MDT THU JUL 18 2013 .UPDATE... ISSUED AT 1105 PM MDT THU JUL 18 2013 CONVECTION OVER PHILLIPS AND LOGAN COUNTIES IN COLORADO IS HAVING A DIFFICULT TIME MOVING INTO YUMA COUNTY. WILL KEEP A MENTION OF SOME STORMS THROUGH THE NIGHT THERE GIVEN SOME LOW LEVEL MOISTYRE CONVERGENCE...THOUGH THE HRRR MODEL NEVER BRINGS PRECIPITATION TO THE COUNTY THROUGH 12Z. SURFACE TROUGH HAS MOVED THROUGH FLAGLER AND YUMA...AND WILL ADJUST WIND DIRECTIONS OVER THE WESTERN HALF OF THE FORECAST AREA. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 228 PM MDT THU JUL 18 2013 AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE CLEAR. TEMPERATURES HAVE RISEN INTO THE MID 80S TO LOW 90S. GUSTY SOUTH WINDS CONTINUE THIS AFTERNOON DUE TO A LEE TROUGH OVER CENTRAL COLORADO AND A HIGH PRESSURE LOCATED TO THE SOUTH. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE ROCKIES THIS AFTERNOON. A COLD FRONT WAS LOCATED TO THE NORTH...IN THE VICINITY OF THE SOUTH DAKOTA AND NEBRASKA BORDER AND INTO SOUTHWEST WYOMING. FOR TONIGHT...MODELS INDICATE THAT SOME OF THE SHOWERS AND STORMS WILL MOVE TO THE EAST OFF THE TERRAIN. UNFORTUNATELY...MODELS SEEM PRETTY CONSISTENT IN SHOWING THAT ALL OF THE ACTIVITY WILL DIMINISH BEFORE MOVING INTO THE REGION. THE WEAK COLD FRONT WILL CONTINUE MOVING TO THE SOUTH TONIGHT...ENTERING THE REGION AROUND MIDNIGHT WITH A SLOW MOVEMENT TO THE SOUTH THROUGH THE OVERNIGHT HOURS. A FEW SHOWERS ARE POSSIBLE ALONG THE FRONT TONIGHT...MAINLY IN SOUTHWEST NEBRASKA AND NORTHEAST COLORADO. LOW TEMPERATURES TONIGHT SHOULD FALL INTO THE LOW TO UPPER 60S WITH COOLEST TEMPERATURES EXPECTED OVER EAST COLORADO. GUSTY SOUTH WINDS WILL DIMINISH THIS EVENING AS THE PRESSURE GRADIENT RELAXES. A PERIOD OF CALM WINDS IS ANTICIPATED JUST AHEAD OF THE COLD FRONT BEFORE NORTH TO NORTHEAST WINDS OF 5 TO 15 MPH BEGIN IN THE MORNING HOURS. FOR TOMORROW...THE WEAK COLD FRONT WILL CONTINUE A SLUGGISH SOUTHWARD PUSH. HIGHER DEWPOINTS THAN PREVIOUS DAYS ARE EXPECTED TO POOL ALONG AND JUST AHEAD OF THE FRONT. WITH THE INCREASED MOISTURE AND HIGH TEMPERATURES CLIMBING INTO THE LOW TO MID 90S AHEAD OF THE FRONT...INSTABILITY AND FRONTAL SURFACE CONVERGENCE SHOULD BE ENOUGH FOR SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP. EVEN THOUGH INSTABILITY WOULD BE ENOUGH TO SUPPORT SOME POSSIBLE SEVERE THUNDERSTORMS...WEAK LAPSE RATES AND LITTLE SHEAR LEAD ONE TO THINK THAT WIDESPREAD SEVERE WEATHER IS NOT LIKELY. A STRONG STORM OR TWO IS POSSIBLE BUT THAT SHOULD BE ABOUT IT. WITH PRECIPITABLE WATER VALUES AROUND 1.5 INCHES AND SLOW STORM MOTIONS...HEAVY DOWNPOURS SEEM LIKE A GOOD BET FOR THE STRONGER THUNDERSTORMS. WINDS WILL SHIFT TO THE EAST BEHIND THE WEAK COLD FRONT. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 228 PM MDT THU JUL 18 2013 FRIDAY NIGHT ELEVATED CAPE WILL EXIST OVER THE AREA UNTIL THE OVERNIGHT HOURS...WITH THE BEST CAPE DURING THE EVENING. THERE IS NO CLEAR AREA OF MID/UPPER LEVEL LIFT BUT THERE IS SOME LOW LEVEL CONVERGENCE ACROSS THE CENTRAL PART OF AREA. THE ELEVATED CAPE AND LOW LEVEL CONVERGENCE/WEAK COLD FRONT MAY ALLOW FOR SOME STORMS TO DEVELOP/CONTINUE...BUT CONFIDENCE AT THIS TIME IS FAIRLY LOW. THOUGHT ABOUT TRENDING PRECIP. CHANCES ACCORDING TO WHERE THE LOW LEVEL CONVERGENCE DEVELOPS...BUT INSTEAD KEPT THE BROAD PRECIP. CHANCES GOING THROUGH THE EVENING. DURING THE OVERNIGHT HOURS THE LOW LEVEL CONVERGENCE DWINDLES FROM EAST TO WEST AS THE MID LEVEL MOISTURE AND ELEVATED CAPE DECLINE...SO HAVE PRECIP. CHANCES TRENDING ACCORDINGLY. SATURDAY THE LOW LEVEL CONVERGENCE RETURNS TO THE AREA AGAIN. SOUNDINGS INDICATE THE MID LEVELS MOISTENING DURING THE AFTERNOON. WILL AGAIN KEEP PRECIP. CHANCES KIND OF BROAD BUT KEEP THEM OVER THE SOUTH HALF OF THE AREA WHERE THE LOW LEVEL CONVERGENCE IS BETTER. ONE OF THE MODELS BRINGS IN A COLD POOL/COLD FRONT DURING THE AFTERNOON FROM THE NORTH. DO NOT HAVE MUCH CONFIDENCE IN THIS SOLUTION SINCE OTHER MODELS ARE NOT SHOWING IT. SATURDAY EVENING AN UPPER LEVEL TROUGH AND COLD FRONT MOVE INTO THE AREA FROM THE NORTH. THE BEST CHANCE FOR PRECIP. WILL BE DURING THE EVENING OVER ROUGHLY THE EASTERN HALF OF THE AREA WHERE THE BEST UPPER LEVEL LIFT WILL TRACK ACROSS. OVERNIGHT PRECIP. CHANCES COME TO AN END AS DRIER AIR MOVES IN BEHIND THE UPPER LEVEL TROUGH. THE MAIN THREAT FROM ANY STORMS WILL BE HEAVY RAINFALL FRIDAY EVENING DUE TO MEAN STORM MOTIONS OF 5 TO 10 KTS AND 0-6KM SHEAR OF 10 TO 15KTS. SATURDAY THE 0-6KM SHEAR INCREASES TO 30KTS WHICH WILL BE MORE FAVORABLE FOR SEVERE THUNDERSTORMS. SUNDAY THROUGH THURSDAY A COUPLE WEAK COLD FRONTS/SURFACE TROUGHS ACCOMPANIED BY AN UPPER LEVEL SHORT WAVE TROUGH MOVE ACROSS THE AREA EARLY IN THE WEEK...BRINGING PRECIP CHANCES TO THE AREA. MID WEEK A SURFACE TROUGH DEVELOPS OVER THE SOUTHWEST PART OF THE AREA AND PUSHES NORTH THURSDAY BRINGING ANOTHER ROUND OF PRECIP. CHANCES FOR THE AREA. HIGH TEMPERATURES FOR THE PERIOD WILL WARM TO ABOVE NORMAL BY THE START OF THE WORK WEEK THEN COOL DOWN TO NEAR NORMAL BY MID WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1105 PM MDT THU JUL 18 2013 SURFACE TROUGH WILL MOVE EAST THROUGH EASTERN COLORADO...AND WILL REACH KGLD AROUND 09Z. THIS WILL SWITCH THE SURFACE WINDS TO THE WEST. EXPECT WIND SHIFT AT KMCK AROUND 12Z. VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD...BUT EXPECT CONVECTION TO DEVELOP AFTER 18Z. THERE WILL BE CHANCE OF THUNDERSTORMS AT BOTH KGLD/KMCK...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INDICATE STORMS IN THE TAFS. IF STORMS DO MOVE OVER THE SITES...VISIBILITIES WILL DROP TO MVFR OR LOWER IN BRIEF HEAVY RAIN. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...MENTZER SHORT TERM...RRH LONG TERM...JTL AVIATION...MENTZER
AREA FORECAST DISCUSSION
NWS JACKSON KY
1028 PM EDT SAT JUL 20 2013 .UPDATE... ISSUED AT 1025 PM EDT SAT JUL 20 2013 MOST SHOWERS AND THUNDERSTORMS HAVE DIMINISHED TO OUR NORTH AND EAST. HOWEVER...A LARGE LINE OF WEAK CONVECTION HAS DEVELOPED TO OUR WEST AND CONTINUES TO SLOWLY MAKE ITS WAY EASTWARD. EXPECT SOME CONTIUED WEAKENING BY THE TIME IT REACHES EASTERN KY...THOUGH LOW END CHANCES/SCT COVERAGE IS STILL WARRANTED BASED ON LATEST MODEL RUNS. UPDATED POPS TO REFLECT THIS LATEST RADAR TREND...WITH SCT CHANCES MOVING IN ACROSS THE WESTERN CWA IN THE NEXT COUPLE OF HOURS...AND THEN SPREADING ACROSS THE REMAINING CWA BY LATE TONIGHT. UPDATE ISSUED AT 527 PM EDT SAT JUL 20 2013 BASED ON CURRENT RADAR TRENDS...DIDN/T FEEL CONFIDENT IN NO POPS ACROSS THE AREA THIS AFTERNOON/EVENING. WENT AHEAD AND ADDED IN SOME SLIGHT CHANCES ALONG THE NORTHERN AND SOUTHEASTERN SECTIONS OF THE CWA THROUGH THIS AFTERNOON IN CASE SOME SHORT LIVED CONVECTION DEVELOPS. THEN HAVE ISOLATED CHANCES TAPERING OFF ACROSS THE SOUTHEAST THIS EVENING AS BEST INSTABILITY BECOMES FOCUSED OVER THE NORTHERN CWA WITH AN IMPOSING COLD FRONT AND AREA OF CONVECTION MOVING INTO THE REGION. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 325 PM EDT SAT JUL 20 2013 CONTINUING TO WATCH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DROPPING SOUTHWARD ACROSS THE OHIO RIVER VALLEY. A GAP IN THE LINE HAS OPENED UP JUST TO OUR NORTH. WHILE SHOWERS AND STORMS ARE STILL POSSIBLE THIS EVENING INTO TONIGHT...EVERY HRRR RUN OVER THE PAST SEVERAL HOURS CONTINUES TO BACK OFF ON OVERALL COVERAGE ACROSS EASTERN KENTUCKY THIS EVENING...WITH EVERYTHING FADING AWAY AROUND SUNSET. THUS...HAVE DECREASED POPS INTO THIS EVENING AND THE OVERNIGHT HOURS. THIS TREND MAY HAVE TO BE CONTINUED ON THE EVENING SHIFT IF THE TRENDS CONTINUE THE WAY THEY ARE HEADING. REGARDLESS...THE PROSPECTS FOR WIDESPREAD SHOWERS AND THUNDERSTORMS IS DRASTICALLY LESS NOW. WILL MAINTAIN LOW 20-30 POPS THROUGH THE OVERNIGHT HOURS. WITH THE BOUNDARY WASHED OUT OVER THE AREA TOMORROW...DAYTIME HEATING SHOULD ALLOW FOR QUICK REDEVELOPMENT AFTER SUNRISE. COVERAGE SHOULD BE DECENT TOMORROW...SO OPTED TO STAY WITH OUR 60-70 POPS. THERE IS SOME QUESTION AS TO HOW MUCH ACTIVITY WILL THEN LINGER INTO TOMORROW NIGHT AS THE QUASI BOUNDARY MAY SHIFT BACK TO THE NORTH. LACK OF OVERNIGHT INSTABILITY MAY KEEP THINGS FAIRLY LOW KEY FOR MUCH OF THE NIGHT. THERE IS A SHORTWAVE TROUGH PUSHING ACROSS THE AREA LATE IN THE NIGHT THAT COULD ACT TO FIRE OFF SOME SHOWERS AND THUNDERSTORMS...SO WILL INCREASE POPS THROUGH THE NIGHT. TEMPERATURES ON SUNDAY SHOULD BE SLIGHTLY LOWER WITH THE INCREASED CLOUD COVER AND PRECIPITATION. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 325 PM EDT SAT JUL 20 2013 THE MODELS BASICALLY AGREE ON THE GENERAL MID LEVEL PATTERN THROUGH THE BULK OF THE EXTENDED FORECAST. A TROUGH WILL DEVELOP THROUGH THE OHIO VALLEY INITIALLY AS ENERGY FROM THE NORTHERN PLAINS POOLS OVER THE REGION. THIS TROUGH EVOLVES GRADUALLY AS A COUPLE OF CYCLES OF WAVES MOVE THROUGH THE OHIO VALLEY...EACH DEPICTED SLIGHTLY DIFFERENT BY THE MODELS. THIS SEMI-STATIONARY TROUGH BOTTOMS OUT ON THURSDAY PER A CONSENSUS OF SOLUTIONS. EACH MODEL HAS ENOUGH OF A DIFFERENT HANDLING OF THE INDIVIDUAL WAVES THAT A BLENDED APPROACH IS PREFERRED FOR EXTENDED FORECASTING PURPOSES. IT DOES LOOK LIKE HEIGHTS WILL RISE A BIT ON FRIDAY AS THE CORE OF THE TROUGH SHIFTS TEMPORARILY EAST BUT THE ECMWF IS MOST AGGRESSIVE IN TAKING ANOTHER DECENT WAVE FROM THE PLAINS EAST INTO THE OHIO VALLEY FOR THE WEEKEND LIKELY RESTORING THE TROUGH FOR THE OHIO VALLEY. THE GFS HAS A VERSION OF THIS THAT ALSO LOWERS HEIGHTS OVER THE OHIO VALLEY ON SATURDAY...BUT DOES SO BY RELYING ON WAVES FURTHER NORTH THAN THE ECMWF...MAINLY MOVING THEM THROUGH THE GREAT LAKES. AGAIN HERE... WILL FAVOR A CONSENSUS SOLUTION FOR WEATHER DETAILS. SENSIBLE WEATHER WILL FEATURE A VERY UNSETTLED SITUATION TO START THE EXTENDED AS MID LEVEL WAVES ACTIVATE SHOWERS AND THUNDERSTORMS ALONG AND SOUTH OF A FRONTAL BOUNDARY RUNNING JUST NORTH OF THE OHIO RIVER. THERE WILL BE PLENTY OF HIGH PW AIR IN PLACE TO SUPPORT THE STORMS AND THUS A HEAVY RAIN POTENTIAL WILL EXIST THROUGH THE DAY...MONDAY. THE NEXT SFC BOUNDARY WILL APPROACH THE AREA ON TUESDAY CONTINUING OUR CHANCES OF SHOWERS AND THUNDERSTORMS. THIS CONVECTION IS EXPECTED TO LINGER INTO THE NIGHT WHEN THE BOUNDARY DROPS THROUGH THE CWA IN THE FORM OF A COLD FRONT. FOR THURSDAY AND FRIDAY...ANY CONVECTION SHOULD BE AT A MINIMUM IN THE WAKE OF THE SFC FRONT AND SLIGHTLY HIGHER HEIGHTS ALOFT. HOWEVER...THE NEXT SFC SYSTEM LOOKS TO BRING A RENEWED CHANCE OF CONVECTION TO THE AREA ON SATURDAY...SPURRED ON BY FALLING HEIGHTS AND MORE INBOUND MID-LEVEL ENERGY. THE CR GRID LOAD CAME IN PRETTY GOOD CONSIDERING THE SMALLER SCALE DIFFERENCES AMONG THE MODELS WITH RESPECT TO WEATHER DETAILS THROUGH THE EXTENDED. DID NUDGE DOWN POPS A BIT LATE IN THE FORECAST...MORE TOWARD THE OPERATIONAL ECMWF. ALSO...ADJUSTED OVERNIGHT LOWS A TAD FOR WEDNESDAY AND THURSDAY NIGHT TO BETTER EMPHASIZE RIDGE AND VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 744 PM EDT SAT JUL 20 2013 A WEAK COLD FRONT WILL PUSH SOUTHEAST AND STALL OVER NORTHERN KENTUCKY OVERNIGHT. A COMPLEX OF SHOWERS AND STORMS CONTINUES TO OUR NORTH AHEAD OF THIS LINE...CURRENTLY OVER SOUTHERN INDIANA AND OHIO...BUT RADAR TRENDS ARE NOT SHOWING MUCH PROMISE FOR THIS COMPLEX TO MOVE FAR ENOUGH SOUTH IN WHICH STORMS WILL AFFECT ANY TAF SITES DURING THE NIGHT. IF ANYTHING DOES DEVELOP IT SHOULD BE ISOLATED...WITH CONFIDENCE BEING TOO LOW TO INCLUDE IN TAFS AT THIS TIME. BY TOMORROW MORNING...HOWEVER...FRONT WILL MOVE SLIGHTLY SOUTHWARD. THIS WILL BE THE PUSH NEEDED TO BRING SCT TO NUMEROUS SHOWERS AND THUNDERSTORMS TO THE AREA AND TAF SITES...WITH BEST COVERAGE DURING THE LATE MORNING/MID AFTERNOON HOURS. FRONT WILL THEN BOUNCE BACK NORTHWARD...BRINGING AN END TO BEST COVERAGE BY LATE AFTERNOON. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...KAS LONG TERM...GREIF AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
744 PM EDT SAT JUL 20 2013 .UPDATE... ISSUED AT 527 PM EDT SAT JUL 20 2013 BASED ON CURRENT RADAR TRENDS...DIDN/T FEEL CONFIDENT IN NO POPS ACROSS THE AREA THIS AFTERNOON/EVENING. WENT AHEAD AND ADDED IN SOME SLIGHT CHANCES ALONG THE NORTHERN AND SOUTHEASTERN SECTIONS OF THE CWA THROUGH THIS AFTERNOON IN CASE SOME SHORT LIVED CONVECTION DEVELOPS. THEN HAVE ISOLATED CHANCES TAPERING OFF ACROSS THE SOUTHEAST THIS EVENING AS BEST INSTABILITY BECOMES FOCUSED OVER THE NORTHERN CWA WITH AN IMPOSING COLD FRONT AND AREA OF CONVECTION MOVING INTO THE REGION. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 325 PM EDT SAT JUL 20 2013 CONTINUING TO WATCH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DROPPING SOUTHWARD ACROSS THE OHIO RIVER VALLEY. A GAP IN THE LINE HAS OPENED UP JUST TO OUR NORTH. WHILE SHOWERS AND STORMS ARE STILL POSSIBLE THIS EVENING INTO TONIGHT...EVERY HRRR RUN OVER THE PAST SEVERAL HOURS CONTINUES TO BACK OFF ON OVERALL COVERAGE ACROSS EASTERN KENTUCKY THIS EVENING...WITH EVERYTHING FADING AWAY AROUND SUNSET. THUS...HAVE DECREASED POPS INTO THIS EVENING AND THE OVERNIGHT HOURS. THIS TREND MAY HAVE TO BE CONTINUED ON THE EVENING SHIFT IF THE TRENDS CONTINUE THE WAY THEY ARE HEADING. REGARDLESS...THE PROSPECTS FOR WIDESPREAD SHOWERS AND THUNDERSTORMS IS DRASTICALLY LESS NOW. WILL MAINTAIN LOW 20-30 POPS THROUGH THE OVERNIGHT HOURS. WITH THE BOUNDARY WASHED OUT OVER THE AREA TOMORROW...DAYTIME HEATING SHOULD ALLOW FOR QUICK REDEVELOPMENT AFTER SUNRISE. COVERAGE SHOULD BE DECENT TOMORROW...SO OPTED TO STAY WITH OUR 60-70 POPS. THERE IS SOME QUESTION AS TO HOW MUCH ACTIVITY WILL THEN LINGER INTO TOMORROW NIGHT AS THE QUASI BOUNDARY MAY SHIFT BACK TO THE NORTH. LACK OF OVERNIGHT INSTABILITY MAY KEEP THINGS FAIRLY LOW KEY FOR MUCH OF THE NIGHT. THERE IS A SHORTWAVE TROUGH PUSHING ACROSS THE AREA LATE IN THE NIGHT THAT COULD ACT TO FIRE OFF SOME SHOWERS AND THUNDERSTORMS...SO WILL INCREASE POPS THROUGH THE NIGHT. TEMPERATURES ON SUNDAY SHOULD BE SLIGHTLY LOWER WITH THE INCREASED CLOUD COVER AND PRECIPITATION. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 325 PM EDT SAT JUL 20 2013 THE MODELS BASICALLY AGREE ON THE GENERAL MID LEVEL PATTERN THROUGH THE BULK OF THE EXTENDED FORECAST. A TROUGH WILL DEVELOP THROUGH THE OHIO VALLEY INITIALLY AS ENERGY FROM THE NORTHERN PLAINS POOLS OVER THE REGION. THIS TROUGH EVOLVES GRADUALLY AS A COUPLE OF CYCLES OF WAVES MOVE THROUGH THE OHIO VALLEY...EACH DEPICTED SLIGHTLY DIFFERENT BY THE MODELS. THIS SEMI-STATIONARY TROUGH BOTTOMS OUT ON THURSDAY PER A CONSENSUS OF SOLUTIONS. EACH MODEL HAS ENOUGH OF A DIFFERENT HANDLING OF THE INDIVIDUAL WAVES THAT A BLENDED APPROACH IS PREFERRED FOR EXTENDED FORECASTING PURPOSES. IT DOES LOOK LIKE HEIGHTS WILL RISE A BIT ON FRIDAY AS THE CORE OF THE TROUGH SHIFTS TEMPORARILY EAST BUT THE ECMWF IS MOST AGGRESSIVE IN TAKING ANOTHER DECENT WAVE FROM THE PLAINS EAST INTO THE OHIO VALLEY FOR THE WEEKEND LIKELY RESTORING THE TROUGH FOR THE OHIO VALLEY. THE GFS HAS A VERSION OF THIS THAT ALSO LOWERS HEIGHTS OVER THE OHIO VALLEY ON SATURDAY...BUT DOES SO BY RELYING ON WAVES FURTHER NORTH THAN THE ECMWF...MAINLY MOVING THEM THROUGH THE GREAT LAKES. AGAIN HERE... WILL FAVOR A CONSENSUS SOLUTION FOR WEATHER DETAILS. SENSIBLE WEATHER WILL FEATURE A VERY UNSETTLED SITUATION TO START THE EXTENDED AS MID LEVEL WAVES ACTIVATE SHOWERS AND THUNDERSTORMS ALONG AND SOUTH OF A FRONTAL BOUNDARY RUNNING JUST NORTH OF THE OHIO RIVER. THERE WILL BE PLENTY OF HIGH PW AIR IN PLACE TO SUPPORT THE STORMS AND THUS A HEAVY RAIN POTENTIAL WILL EXIST THROUGH THE DAY...MONDAY. THE NEXT SFC BOUNDARY WILL APPROACH THE AREA ON TUESDAY CONTINUING OUR CHANCES OF SHOWERS AND THUNDERSTORMS. THIS CONVECTION IS EXPECTED TO LINGER INTO THE NIGHT WHEN THE BOUNDARY DROPS THROUGH THE CWA IN THE FORM OF A COLD FRONT. FOR THURSDAY AND FRIDAY...ANY CONVECTION SHOULD BE AT A MINIMUM IN THE WAKE OF THE SFC FRONT AND SLIGHTLY HIGHER HEIGHTS ALOFT. HOWEVER...THE NEXT SFC SYSTEM LOOKS TO BRING A RENEWED CHANCE OF CONVECTION TO THE AREA ON SATURDAY...SPURRED ON BY FALLING HEIGHTS AND MORE INBOUND MID-LEVEL ENERGY. THE CR GRID LOAD CAME IN PRETTY GOOD CONSIDERING THE SMALLER SCALE DIFFERENCES AMONG THE MODELS WITH RESPECT TO WEATHER DETAILS THROUGH THE EXTENDED. DID NUDGE DOWN POPS A BIT LATE IN THE FORECAST...MORE TOWARD THE OPERATIONAL ECMWF. ALSO...ADJUSTED OVERNIGHT LOWS A TAD FOR WEDNESDAY AND THURSDAY NIGHT TO BETTER EMPHASIZE RIDGE AND VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 744 PM EDT SAT JUL 20 2013 A WEAK COLD FRONT WILL PUSH SOUTHEAST AND STALL OVER NORTHERN KENTUCKY OVERNIGHT. A COMPLEX OF SHOWERS AND STORMS CONTINUES TO OUR NORTH AHEAD OF THIS LINE...CURRENTLY OVER SOUTHERN INDIANA AND OHIO...BUT RADAR TRENDS ARE NOT SHOWING MUCH PROMISE FOR THIS COMPLEX TO MOVE FAR ENOUGH SOUTH IN WHICH STORMS WILL AFFECT ANY TAF SITES DURING THE NIGHT. IF ANYTHING DOES DEVELOP IT SHOULD BE ISOLATED...WITH CONFIDENCE BEING TOO LOW TO INCLUDE IN TAFS AT THIS TIME. BY TOMORROW MORNING...HOWEVER...FRONT WILL MOVE SLIGHTLY SOUTHWARD. THIS WILL BE THE PUSH NEEDED TO BRING SCT TO NUMEROUS SHOWERS AND THUNDERSTORMS TO THE AREA AND TAF SITES...WITH BEST COVERAGE DURING THE LATE MORNING/MID AFTERNOON HOURS. FRONT WILL THEN BOUNCE BACK NORTHWARD...BRINGING AN END TO BEST COVERAGE BY LATE AFTERNOON. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...KAS LONG TERM...GREIF AVIATION...JMW
AREA FORECAST DISCUSSION
NWS PADUCAH KY
630 PM CDT SAT JUL 20 2013 .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... ISSUED AT 200 PM CDT SAT JUL 20 2013 18Z MESOANALYSIS SHOWS A COLD FRONT EXTENDING WESTWARD ACROSS CENTRAL INDIANA TO A WEAK SURFACE LOW OVER CENTRAL ILLINOIS. A SURFACE TROUGH EXTENDS SOUTHWEST FROM THE LOW CENTER TO NEAR KFAM AND THEN BETWEEN KUNO/KPOF. DEW POINTS POOLING INTO THE LOWER AND MID 70S ALONG THE TROUGH AND COLD FRONT HAVE CONTRIBUTED TO VERY UNSTABLE CAPES LOCALLY OVER 3000 J/KG. ISOLATED STORMS HAVE POPPED UP ALONG THE SURFACE TROUGH OVER MISSOURI...WHILE LARGER CLUSTERS OF STORMS ARE EAST OF THE SURFACE LOW CENTER IN INDIANA/EAST CENTRAL IL. THROUGH THE EVENING HOURS...THE COLD FRONT IS FORECAST TO DRIFT SOUTH TO THE INTERSTATE 64 CORRIDOR WHILE THE SURFACE TROUGH REMAINS STATIONARY OVER THE MISSOURI OZARKS. THE LATEST HRRR MODEL REFLECTIVITY INDICATES THAT CLUSTERS OF STORMS /POSSIBLE MCS/ WILL PROPAGATE SOUTH ALONG THE WABASH VALLEY...REACHING THE PENNYRILE REGION OF WESTERN KY THIS EVENING. THIS SCENARIO IS SUPPORTED BY THE 12Z HIGH RES NMM. OTHER ISOLATED STORMS MAY DEVELOP EASTWARD FROM THE SURFACE TROUGH OVER MISSOURI. VERY LIMITED SHEAR MAGNITUDE WILL LIMIT SEVERE POTENTIAL TO ISOLATED PULSE EVENTS...THOUGH AN ORGANIZED COLD POOL COULD DEVELOP WITH THE WABASH VALLEY MCS. ACTIVITY WILL WEAKEN SIGNIFICANTLY BY 06Z AS THE BOUNDARY LAYER COOLS AND STABILIZES. ON SUNDAY...THE SURFACE FRONT IS FORECAST TO SLOWLY LIFT BACK NORTH AS A WARM FRONT. A MINOR 500 MB SHORTWAVE WILL MOVE EAST/SOUTHEAST ACROSS THE MISSISSIPPI VALLEY. THIS SHORTWAVE WILL HELP REJUVENATE CONVECTION ALONG AND SOUTH OF THE FRONT...ESPECIALLY DURING THE WARMER AND MORE UNSTABLE AFTERNOON HOURS. HIGH TEMPS WILL STRUGGLE TO REACH THE UPPER 80S DUE TO ABUNDANT CLOUDINESS AND CONVECTION. ON SUNDAY NIGHT...A RATHER WELL DEVELOPED 500 MB SHORTWAVE FOR MID SUMMER WILL APPROACH FROM THE CENTRAL PLAINS. THIS SHORTWAVE WILL TAP A VERY MOIST AND UNSTABLE SOUTHWEST WIND FLOW. SHOWERS AND STORMS ARE LIKELY OVERNIGHT INTO MONDAY MORNING...UNTIL THE PASSAGE OF THE SHORTWAVE. ONCE AGAIN...SEASONABLY WEAK SHEAR PROFILES WILL LIMIT THE POTENTIAL HAZARDS TO MAINLY HEAVY RAIN AND FREQUENT LIGHTNING. ON MONDAY AFTERNOON AND MONDAY NIGHT...PRECIP COVERAGE WILL GRADUALLY DECREASE WITH THE PASSAGE OF THE SHORTWAVE. 850 MB WARM ADVECTION WILL BE COUNTERED BY EXTENSIVE CLOUD COVER AND PRECIP... SO DAYTIME HIGHS ON MONDAY WILL ONLY BE NEAR SEASONAL NORMS. OVERNIGHT LOWS WILL BE NEAR SURFACE DEW POINTS IN THE LOWER 70S. .LONG TERM /TUESDAY THROUGH SATURDAY/... ISSUED AT 200 PM CDT SAT JUL 20 2013 THE MODELS ARE IN A LITTLE BETTER AGREEMENT WITH THE TIMING OF THE MID WEEK FRONT. THIS FRONT WILL PROVIDE THE FOCUS FOR THUNDERSTORMS TUESDAY THEN TAPERING OFF INTO WEDNESDAY. WEAK HIGH PRESSURE WILL DRY US OUT FOR AT LEAST THURSDAY AND FRIDAY WITH AT LEAST A CHANCE RETURNING FRIDAY NIGHT INTO SATURDAY AS YET ANOTHER COLD FRONT ENTERS THE PICTURE AT THE SAME TIME A WARM FRONT TRIES TO LIFT OUT OF THE PLAINS INTO THE REGION. THE LATEST RUNS WOULD HAVE THE COLD FRONT WINNING OUT AND SUPPRESSING THE WARM FRONT TO THE SOUTHWEST. HOWEVER...THE SIGNALS ARE VERY WEAK AND MAY FLIP FLOP WITH LATER RUNS. THIS WOULD ALSO RESULT IN A SIGNIFICANT CHANGE FOR TEMPS THIS WEEKEND. EITHER WAY ONE SYSTEM OR THE OTHER WILL PROVIDE A CHANCE FOR THUNDERSTORMS. AS FOR TEMPS FOLLOWED THE ONGOING TREND WITH THE WARMEST DAY TUESDAY THEN COOLING AND A BIT DRIER LATE IN THE WEEK. TEMPS BEGIN TO SOAR BACK TO AROUND 90 LATE IN THE WEEK AHEAD OF THE APPROACHING COLD FRONT. IF THE WEEKEND COLD FRONT MAKES IT THROUGH THE AREA WE WILL COOL BACK INTO THE 80S AGAIN HOWEVER SHOULD THE WARM FRONT OVERTAKE THE REGION WILL HAVE TO ADJUST TEMPS UP FROM CURRENT FORECAST. && .AVIATION... ISSUED AT 630 PM CDT SAT JUL 20 2013 CONVECTIVE COMPLEXES DEVELOPED THIS AFTERNOON ACROSS SOUTHERN IN/SRN ILLINOIS/SE MISSOURI. THE LEADING EDGE OF THE OUTFLOW WINDS FROM THIS ACTIVITY PASSED ACROSS KEVV/KCGI TAF SITES...AND WILL BE CROSSING KOWB/KPAH VERY SOON. SOME BRIEF CIG AND VSBY RESTRICTIONS ARE LIKELY IN THE STORMS...MAINLY AT KEVV/KOWB EARLY THIS EVENING. HOWEVER...THE ACTIVITY APPEARS TO BE STARTING TO WEAKEN ALREADY...AND THIS TREND WILL CONTINUE THIS EVENING. WINDS WILL BECOME LIGHT AND VARIABLE OVERNIGHT...ALLOWING SOME LIGHT FOG OR HAZE TO FORM AS SKIES BECOME MOSTLY CLEAR. MID LEVEL CLOUDS WILL INCREASE AHEAD OF AN UPPER LEVEL DISTURBANCE EARLY SUNDAY. SCATTERED SHOWERS MAY DEVELOP AFTER SUNRISE AS THE FRONT BEGINS TO MOVE BACK NORTH AS A WARM FRONT. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ SHORT TERM...MY LONG TERM...KH AVIATION...MY
AREA FORECAST DISCUSSION
NWS JACKSON KY
223 PM EDT FRI JUL 19 2013 .UPDATE... ISSUED AT 223 PM EDT FRI JUL 19 2013 SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED...WITH THE GREATEST CONCENTRATION OVER THE SW PART OF THE AREA...MOVING ENE. BASED ON RADAR TRENDS...HAVE RAISED AFTERNOON POPS SLIGHTLY...BUT STILL IN THE CHANCE CATEGORY. UPDATE ISSUED AT 945 AM EDT FRI JUL 19 2013 FOG PERSISTED IN THE UPPER REACHES OF THE CUMBERLAND VALLEY AT MID MORNING...BUT HAD DISSIPATED ELSEWHERE...AND SHOULD SOON BE GONE EVERYWHERE. OUTSIDE OF FOG...SKIES WERE GENERALLY CLEAR AT MID MORNING. HAVE DELAYED THE INCREASE IN CLOUD COVER AND PRECIP TODAY... WITH WIDESPREAD CU DEVELOPMENT EXPECTED AROUND MID DAY...AND SCATTERED SHOWERS AND THUNDERSTORMS TO SOON FOLLOW. UPDATE ISSUED AT 745 AM EDT FRI JUL 19 2013 FOG CONTINUES TO LIFT UP TO THE RIDGE TOP LEVEL IN SOUTHEASTERN KY. K22... JKL AND I35 ARE CURRENTLY EXPERIENCING DENSE FOG. THIS SHOULD LIFT AND DISSIPATE BY AROUND 9 AM. THE HWO...ZFP AND GRIDS ALREADY HAD A HANDLE ON THIS. HOURLY TEMPS AND DEW POINTS WERE FRESHENED UP BASED ON RECENT OBS. OVERALL...THE FORECAST REMAINS ON TRACK. THE 6Z NAM AND MOST RECENT HRRR RUN APPEAR TO DEVELOP CONVECTION TOO QUICKLY AND BOTH HAVE CONVECTION NEAR THE OH RIVER THAT IS NOT OCCURRING. HOWEVER...DIURNALLY DRIVEN SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...AFTER 16Z. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 325 AM EDT FRI JUL 19 2013 EARLY THIS MORNING...A RIDGE OF HIGH PRESSURE WAS LOCATED OVER THE WESTERN CONUS WITH ANOTHER RIDGE CENTERED OVER VA WITH A BIT OF A WEAKNESS IN BETWEEN. MEANWHILE A CLOSED UPPER LEVEL LOW WAS OVER THE HUDSON BAY REGION IN CENTRAL CANADA. A SERIES OF UPPER LEVEL DISTURBANCES WERE MOVING THROUGH THE WESTERLIES NEAR THE US/CANADIAN BORDER. ONE SHORTWAVE IN PARTICULAR EXTENDED FROM WESTERN ONTARIO DOWN INTO THE NORTHERN PLAINS/UPPER MS VALLEY REGION AND WAS APPROACHING THE WESTERN GREAT LAKES REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS OVER NORTHERN ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST INTO THE UPPER MS VALLEY AND NORTHERN GREAT LAKES REGION. LOCALLY...TEMPS ARE RATHER MILD EVEN FOR JULY WITH MOST LOCATIONS CURRENTLY IN THE LOW TO MID 70S. PATCHY DENSE FOG HAS ALSO FORMED MAINLY IN THE VALLEYS. THROUGH AN HOUR OR TWO PAST DAWN...PATCHY DENSE RIVER VALLEY FOG SHOULD GRADUALLY LIFT AND DISSIPATE. THIS WILL CONTINUE TO BE INCLUDED IN THE HWO AND A PRE-FIRST PERIOD WILL PROBABLY BE USED TO COVER THIS AS WELL. THROUGH THE PERIOD...THE UPPER LEVEL LOW AND LEAD SHORTWAVE WILL ROTATE THROUGH THE GREAT LAKES REGION AND ONTARIO INTO QUEBEC RESPECTIVELY AS THE UPPER LEVEL RIDGE NOW OVER VA WEAKENS AND SHIFTS OFF THE SOUTHEASTERN US COAST AND INTO THE ATLANTIC WITH RIDGING REMAINING OVER THE WESTERN CONUS. THIS COMBINATION WILL LEAD TO A BROAD TROUGH BEING CARVED OUT OVER MUCH OF EASTERN CANADA SOUTH INTO MUCH OF THE EASTERN CONUS. ALTHOUGH THE ASSOCIATED COLD FRONT WILL BECOME INCREASINGLY SHEARED WITH TIME...IT IS EXPECTED TO MOVE THROUGH THE GREAT LAKES AND MUCH OF NEW ENGLAND BY THE END OF THE PERIOD WITH THE TRAILING PORTION OF THE FRONT BECOMINGLY INCREASINGLY WEST TO EAST ORIENTED AS IT APPROACHES THE OH RIVER VALLEY REGION. THIS COLD FRONT AS SHORTWAVES MOVING THROUGH THE FLOW WILL BECOME A FOCUS FOR CONVECTION IN THE OH VALLEY LATE IN THE PERIOD. UNTIL THEN...THE SOURCES FOR FOCUSING CONVECTION OTHER THAN A GRADUAL DECREASE IN HEIGHTS AND ANY LEFTOVER BOUNDARIES FROM CONVECTION IN FRI AS WELL AS DAYTIME HEATING ARE HARD TO DETERMINE. WITH MINIMAL SHEAR AND MODERATE INSTABILITY EXPECTED TODAY...CONVECTION SHOULD BE SCATTERED IN NATURE. A DECREASE IN CONVECTION IS EXPECTED TONIGHT WITH LOSS OF DAYTIME HEATING. TEMPERATURES TODAY WILL BE LARGELY DETERMINED BY TIMING OF DEVELOPMENT OF CU AND ANY SHRA OR TSRA. THE MAV MOS IS LIKELY TOO WARM AS IT WAS YESTERDAY BUT THE COOLER MET NUMBERS ARE PROBABLY DUE TO ITS CONVECTION EARLIER IN THE DAY WHICH SEEMS A BIT SUSPECT. OVERALL..A COMPROMISE OF THE INHERITED FORECAST AND A BLEND OF THE MODEL GUIDANCE WAS USED FOR DAYTIME HEIGHT`S TODAY. DEW POINTS ARE EXPECTED TO REMAIN IN THE LOWER 70S AND THIS WILL LEAD TO HEAT INDEX VALUES IN THE MID TO UPPER 90S IN THE LOWER ELEVATIONS BELOW 2000 FEET AND POSSIBLY TOUCHING 100 IN A FEW SPOTS THIS AFTERNOON. THIS HAS ALREADY BEEN ADDED TO AN HWO UPDATE OVERNIGHT AND WE WILL CONSIDER AN SPS FOR THIS AS WELL. THE APPROACHING FROM AND SHORTWAVE TROUGH SHOULD LEAD TO THE GREATEST COVERAGE OF CONVECTION ON SATURDAY IN THE NORTH WITH MORE SCATTERED CONVECTION FURTHER SOUTH. GREATER CLOUD COVER SHOULD LEAD TO TEMPS ON SAT A BIT BELOW THOSE LATER TODAY. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 AM EDT FRI JUL 19 2013 THE EXTENDED WILL FEATURE A LARGE SCALE EASTERN CONUS TROUGH AND A SLOW MOVING FRONTAL BOUNDARY THAT IS PROGGED TO MEANDER ABOUT THE AREA JUST SOUTH OF THE OHIO RIVER. THE DAYTIME PERIODS WILL BE THE MOST ACTIVE...AS PULSES OF ENERGY MOVE FROM WEST TO EAST ALONG THE NEARLY STATIONARY BOUNDARY DURING THE AFTERNOON AND EVENING PEAK HEATING HOURS. SHOWERS AND THUNDERSTORMS WILL BE WIDESPREAD AND COULD BRING LOCALLY HEAVY RAINFALL TO SOME LOCATIONS...PARTICULARLY SUNDAY THROUGH TUESDAY. THE TROUGH WILL FINALLY PUSH EASTWARD AND OUT OF THE REGION BY THE END OF THE WEEK...AS THE UPPER PARENT TROUGH IS DISPLACED BY A LARGE AREA OF CANADIAN HIGH PRESSURE MIDWEEK ONWARD. TEMPERATURES SUNDAY THROUGH WEDNESDAY WILL LIKELY RUN A BIT BELOW NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION EXPECTED TO AFFECT THE AREA. THE END OF THE NEW WORK WEEK WILL SEE A WARM UP TO MORE NORMAL SUMMERTIME TEMPERATURES...AS A RIDGE OF HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 141 PM EDT FRI JUL 19 2013 THE CYCLE CONTINUES...WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING AGAIN THIS AFTERNOON. LOCALIZED IFR CAN BE EXPECTED IN THUNDERSTORMS AND THE HEAVIER SHOWERS. MOST OF THE PRECIP SHOULD THEN DIE OUT THIS EVENING. FOG IS FORECAST OVERNIGHT...MAINLY IN VALLEYS. THE EXTENT OF THE FOG TONIGHT WILL BE AFFECTED BY THE EXTENT OF RAIN THIS AFTERNOON...WITH AREAS WHICH RECEIVE RAIN LATE IN THE DAY EXPECTED TO HAVE MORE FOG. LOCALIZED IFR WILL OCCUR IN THE FOG. FOG WILL DISSIPATE BY AROUND MID MORNING ON SATURDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS THEN STARTING TO POP UP AGAIN TOWARD THE END OF THE PERIOD. OUTSIDE OF PRECIP AND FOG...MAINLY VFR SHOULD OCCUR. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JP LONG TERM...AR AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
141 PM EDT FRI JUL 19 2013 .UPDATE... ISSUED AT 945 AM EDT FRI JUL 19 2013 FOG PERSISTED IN THE UPPER REACHES OF THE CUMBERLAND VALLEY AT MID MORNING...BUT HAD DISSIPATED ELSEWHERE...AND SHOULD SOON BE GONE EVERYWHERE. OUTSIDE OF FOG...SKIES WERE GENERALLY CLEAR AT MID MORNING. HAVE DELAYED THE INCREASE IN CLOUD COVER AND PRECIP TODAY... WITH WIDESPREAD CU DEVELOPMENT EXPECTED AROUND MID DAY...AND SCATTERED SHOWERS AND THUNDERSTORMS TO SOON FOLLOW. UPDATE ISSUED AT 745 AM EDT FRI JUL 19 2013 FOG CONTINUES TO LIFT UP TO THE RIDGE TOP LEVEL IN SOUTHEASTERN KY. K22... JKL AND I35 ARE CURRENTLY EXPERIENCING DENSE FOG. THIS SHOULD LIFT AND DISSIPATE BY AROUND 9 AM. THE HWO...ZFP AND GRIDS ALREADY HAD A HANDLE ON THIS. HOURLY TEMPS AND DEW POINTS WERE FRESHENED UP BASED ON RECENT OBS. OVERALL...THE FORECAST REMAINS ON TRACK. THE 6Z NAM AND MOST RECENT HRRR RUN APPEAR TO DEVELOP CONVECTION TOO QUICKLY AND BOTH HAVE CONVECTION NEAR THE OH RIVER THAT IS NOT OCCURRING. HOWEVER...DIURNALLY DRIVEN SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...AFTER 16Z. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 325 AM EDT FRI JUL 19 2013 EARLY THIS MORNING...A RIDGE OF HIGH PRESSURE WAS LOCATED OVER THE WESTERN CONUS WITH ANOTHER RIDGE CENTERED OVER VA WITH A BIT OF A WEAKNESS IN BETWEEN. MEANWHILE A CLOSED UPPER LEVEL LOW WAS OVER THE HUDSON BAY REGION IN CENTRAL CANADA. A SERIES OF UPPER LEVEL DISTURBANCES WERE MOVING THROUGH THE WESTERLIES NEAR THE US/CANADIAN BORDER. ONE SHORTWAVE IN PARTICULAR EXTENDED FROM WESTERN ONTARIO DOWN INTO THE NORTHERN PLAINS/UPPER MS VALLEY REGION AND WAS APPROACHING THE WESTERN GREAT LAKES REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS OVER NORTHERN ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST INTO THE UPPER MS VALLEY AND NORTHERN GREAT LAKES REGION. LOCALLY...TEMPS ARE RATHER MILD EVEN FOR JULY WITH MOST LOCATIONS CURRENTLY IN THE LOW TO MID 70S. PATCHY DENSE FOG HAS ALSO FORMED MAINLY IN THE VALLEYS. THROUGH AN HOUR OR TWO PAST DAWN...PATCHY DENSE RIVER VALLEY FOG SHOULD GRADUALLY LIFT AND DISSIPATE. THIS WILL CONTINUE TO BE INCLUDED IN THE HWO AND A PRE-FIRST PERIOD WILL PROBABLY BE USED TO COVER THIS AS WELL. THROUGH THE PERIOD...THE UPPER LEVEL LOW AND LEAD SHORTWAVE WILL ROTATE THROUGH THE GREAT LAKES REGION AND ONTARIO INTO QUEBEC RESPECTIVELY AS THE UPPER LEVEL RIDGE NOW OVER VA WEAKENS AND SHIFTS OFF THE SOUTHEASTERN US COAST AND INTO THE ATLANTIC WITH RIDGING REMAINING OVER THE WESTERN CONUS. THIS COMBINATION WILL LEAD TO A BROAD TROUGH BEING CARVED OUT OVER MUCH OF EASTERN CANADA SOUTH INTO MUCH OF THE EASTERN CONUS. ALTHOUGH THE ASSOCIATED COLD FRONT WILL BECOME INCREASINGLY SHEARED WITH TIME...IT IS EXPECTED TO MOVE THROUGH THE GREAT LAKES AND MUCH OF NEW ENGLAND BY THE END OF THE PERIOD WITH THE TRAILING PORTION OF THE FRONT BECOMINGLY INCREASINGLY WEST TO EAST ORIENTED AS IT APPROACHES THE OH RIVER VALLEY REGION. THIS COLD FRONT AS SHORTWAVES MOVING THROUGH THE FLOW WILL BECOME A FOCUS FOR CONVECTION IN THE OH VALLEY LATE IN THE PERIOD. UNTIL THEN...THE SOURCES FOR FOCUSING CONVECTION OTHER THAN A GRADUAL DECREASE IN HEIGHTS AND ANY LEFTOVER BOUNDARIES FROM CONVECTION IN FRI AS WELL AS DAYTIME HEATING ARE HARD TO DETERMINE. WITH MINIMAL SHEAR AND MODERATE INSTABILITY EXPECTED TODAY...CONVECTION SHOULD BE SCATTERED IN NATURE. A DECREASE IN CONVECTION IS EXPECTED TONIGHT WITH LOSS OF DAYTIME HEATING. TEMPERATURES TODAY WILL BE LARGELY DETERMINED BY TIMING OF DEVELOPMENT OF CU AND ANY SHRA OR TSRA. THE MAV MOS IS LIKELY TOO WARM AS IT WAS YESTERDAY BUT THE COOLER MET NUMBERS ARE PROBABLY DUE TO ITS CONVECTION EARLIER IN THE DAY WHICH SEEMS A BIT SUSPECT. OVERALL..A COMPROMISE OF THE INHERITED FORECAST AND A BLEND OF THE MODEL GUIDANCE WAS USED FOR DAYTIME HEIGHT`S TODAY. DEW POINTS ARE EXPECTED TO REMAIN IN THE LOWER 70S AND THIS WILL LEAD TO HEAT INDEX VALUES IN THE MID TO UPPER 90S IN THE LOWER ELEVATIONS BELOW 2000 FEET AND POSSIBLY TOUCHING 100 IN A FEW SPOTS THIS AFTERNOON. THIS HAS ALREADY BEEN ADDED TO AN HWO UPDATE OVERNIGHT AND WE WILL CONSIDER AN SPS FOR THIS AS WELL. THE APPROACHING FROM AND SHORTWAVE TROUGH SHOULD LEAD TO THE GREATEST COVERAGE OF CONVECTION ON SATURDAY IN THE NORTH WITH MORE SCATTERED CONVECTION FURTHER SOUTH. GREATER CLOUD COVER SHOULD LEAD TO TEMPS ON SAT A BIT BELOW THOSE LATER TODAY. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 AM EDT FRI JUL 19 2013 THE EXTENDED WILL FEATURE A LARGE SCALE EASTERN CONUS TROUGH AND A SLOW MOVING FRONTAL BOUNDARY THAT IS PROGGED TO MEANDER ABOUT THE AREA JUST SOUTH OF THE OHIO RIVER. THE DAYTIME PERIODS WILL BE THE MOST ACTIVE...AS PULSES OF ENERGY MOVE FROM WEST TO EAST ALONG THE NEARLY STATIONARY BOUNDARY DURING THE AFTERNOON AND EVENING PEAK HEATING HOURS. SHOWERS AND THUNDERSTORMS WILL BE WIDESPREAD AND COULD BRING LOCALLY HEAVY RAINFALL TO SOME LOCATIONS...PARTICULARLY SUNDAY THROUGH TUESDAY. THE TROUGH WILL FINALLY PUSH EASTWARD AND OUT OF THE REGION BY THE END OF THE WEEK...AS THE UPPER PARENT TROUGH IS DISPLACED BY A LARGE AREA OF CANADIAN HIGH PRESSURE MIDWEEK ONWARD. TEMPERATURES SUNDAY THROUGH WEDNESDAY WILL LIKELY RUN A BIT BELOW NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION EXPECTED TO AFFECT THE AREA. THE END OF THE NEW WORK WEEK WILL SEE A WARM UP TO MORE NORMAL SUMMERTIME TEMPERATURES...AS A RIDGE OF HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 141 PM EDT FRI JUL 19 2013 THE CYCLE CONTINUES...WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING AGAIN THIS AFTERNOON. LOCALIZED IFR CAN BE EXPECTED IN THUNDERSTORMS AND THE HEAVIER SHOWERS. MOST OF THE PRECIP SHOULD THEN DIE OUT THIS EVENING. FOG IS FORECAST OVERNIGHT...MAINLY IN VALLEYS. THE EXTENT OF THE FOG TONIGHT WILL BE AFFECTED BY THE EXTENT OF RAIN THIS AFTERNOON...WITH AREAS WHICH RECEIVE RAIN LATE IN THE DAY EXPECTED TO HAVE MORE FOG. LOCALIZED IFR WILL OCCUR IN THE FOG. FOG WILL DISSIPATE BY AROUND MID MORNING ON SATURDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS THEN STARTING TO POP UP AGAIN TOWARD THE END OF THE PERIOD. OUTSIDE OF PRECIP AND FOG...MAINLY VFR SHOULD OCCUR. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JP LONG TERM...AR AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
945 AM EDT FRI JUL 19 2013 .UPDATE... ISSUED AT 945 AM EDT FRI JUL 19 2013 FOG PERSISTED IN THE UPPER REACHES OF THE CUMBERLAND VALLEY AT MID MORNING...BUT HAD DISSIPATED ELSEWHERE...AND SHOULD SOON BE GONE EVERYWHERE. OUTSIDE OF FOG...SKIES WERE GENERALLY CLEAR AT MID MORNING. HAVE DELAYED THE INCREASE IN CLOUD COVER AND PRECIP TODAY... WITH WIDESPREAD CU DEVELOPMENT EXPECTED AROUND MID DAY...AND SCATTERED SHOWERS AND THUNDERSTORMS TO SOON FOLLOW. UPDATE ISSUED AT 745 AM EDT FRI JUL 19 2013 FOG CONTINUES TO LIFT UP TO THE RIDGETOP LEVEL IN SOUTHEASTERN KY. K22... JKL AND I35 ARE CURRENTLY EXPERIENCING DENSE FOG. THIS SHOULD LIFT AND DISSIPATE BY AROUND 9 AM. THE HWO...ZFP AND GRIDS ALREADY HAD A HANDLE ON THIS. HOURLY TEMPS AND DEW POINTS WERE FRESHENED UP BASED ON RECENT OBS. OVERALL...THE FORECAST REMAINS ON TRACK. THE 6Z NAM AND MOST RECENT HRRR RUN APPEAR TO DEVELOP CONVECTION TOO QUICKLY AND BOTH HAVE CONVECTION NEAR THE OH RIVER THAT IS NOT OCCURRING. HOWEVER...DIURNALLY DRIVEN SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...AFTER 16Z. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 325 AM EDT FRI JUL 19 2013 EARLY THIS MORNING...A RIDGE OF HIGH PRESSURE WAS LOCATED OVER THE WESTERN CONUS WITH ANOTHER RIDGE CENTERED OVER VA WITH A BIT OF A WEAKNESS IN BETWEEN. MEANWHILE A CLOSED UPPER LEVEL LOW WAS OVER THE HUDSON BAY REGION IN CENTRAL CANADA. A SERIES OF UPPER LEVEL DISTURBANCES WERE MOVING THROUGH THE WESTERLIES NEAR THE US/CANADIAN BORDER. ONE SHORTWAVE IN PARTICULAR EXTENDED FROM WESTERN ONTARIO DOWN INTO THE NORTHERN PLAINS/UPPER MS VALLEY REGION AND WAS APPROACHING THE WESTERN GREAT LAKES REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS OVER NORTHERN ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST INTO THE UPPER MS VALLEY AND NORTHERN GREAT LAKES REGION. LOCALLY...TEMPS ARE RATHER MILD EVEN FOR JULY WITH MOST LOCATIONS CURRENTLY IN THE LOW TO MID 70S. PATCHY DENSE FOG HAS ALSO FORMED MAINLY IN THE VALLEYS. THROUGH AN HOUR OR TWO PAST DAWN...PATCHY DENSE RIVER VALLEY FOG SHOULD GRADUALLY LIFT AND DISSIPATE. THIS WILL CONTINUE TO BE INCLUDED IN THE HWO AND A PRE-FIRST PERIOD WILL PROBABLY BE USED TO COVER THIS AS WELL. THROUGH THE PERIOD...THE UPPER LEVEL LOW AND LEAD SHORTWAVE WILL ROTATE THROUGH THE GREAT LAKES REGION AND ONTARIO INTO QUEBEC RESPECTIVELY AS THE UPPER LEVEL RIDGE NOW OVER VA WEAKENS AND SHIFTS OFF THE SOUTHEASTERN US COAST AND INTO THE ATLANTIC WITH RIDGING REMAINING OVER THE WESTERN CONUS. THIS COMBINATION WILL LEAD TO A BROAD TROUGH BEING CARVED OUT OVER MUCH OF EASTERN CANADA SOUTH INTO MUCH OF THE EASTERN CONUS. ALTHOUGH THE ASSOCIATED COLD FRONT WILL BECOME INCREASINGLY SHEARED WITH TIME...IT IS EXPECTED TO MOVE THROUGH THE GREAT LAKES AND MUCH OF NEW ENGLAND BY THE END OF THE PERIOD WITH THE TRAILING PORTION OF THE FRONT BECOMINGLY INCREASINGLY WEST TO EAST ORIENTED AS IT APPROACHES THE OH RIVER VALLEY REGION. THIS COLD FRONT AS SHORTWAVES MOVING THROUGH THE FLOW WILL BECOME A FOCUS FOR CONVECTION IN THE OH VALLEY LATE IN THE PERIOD. UNTIL THEN...THE SOURCES FOR FOCUSING CONVECTION OTHER THAN A GRADUAL DECREASE IN HEIGHTS AND ANY LEFTOVER BOUNDARIES FROM CONVECTION IN FRI AS WELL AS DAYTIME HEATING ARE HARD TO DETERMINE. WITH MINIMAL SHEAR AND MODERATE INSTABILITY EXPECTED TODAY...CONVECTION SHOULD BE SCATTERED IN NATURE. A DECREASE IN CONVECTION IS EXPECTED TONIGHT WITH LOSS OF DAYTIME HEATING. TEMPERATURES TODAY WILL BE LARGELY DETERMINED BY TIMING OF DEVELOPMENT OF CU AND ANY SHRA OR TSRA. THE MAV MOS IS LIKELY TOO WARM AS IT WAS YESTERDAY BUT THE COOLER MET NUMBERS ARE PROBABLY DUE TO ITS CONVECTION EARLIER IN THE DAY WHICH SEEMS A BIT SUSPECT. OVERALL..A COMPROMISE OF THE INHERITED FORECAST AND A BLEND OF THE MODEL GUIDANCE WAS USED FOR DAYTIME HEIGHT`S TODAY. DEW POINTS ARE EXPECTED TO REMAIN IN THE LOWER 70S AND THIS WILL LEAD TO HEAT INDEX VALUES IN THE MID TO UPPER 90S IN THE LOWER ELEVATIONS BELOW 2000 FEET AND POSSIBLY TOUCHING 100 IN A FEW SPOTS THIS AFTERNOON. THIS HAS ALREADY BEEN ADDED TO AN HWO UPDATE OVERNIGHT AND WE WILL CONSIDER AN SPS FOR THIS AS WELL. THE APPROACHING FROM AND SHORTWAVE TROUGH SHOULD LEAD TO THE GREATEST COVERAGE OF CONVECTION ON SATURDAY IN THE NORTH WITH MORE SCATTERED CONVECTION FURTHER SOUTH. GREATER CLOUD COVER SHOULD LEAD TO TEMPS ON SAT A BIT BELOW THOSE LATER TODAY. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 AM EDT FRI JUL 19 2013 THE EXTENDED WILL FEATURE A LARGE SCALE EASTERN CONUS TROUGH AND A SLOW MOVING FRONTAL BOUNDARY THAT IS PROGGED TO MEANDER ABOUT THE AREA JUST SOUTH OF THE OHIO RIVER. THE DAYTIME PERIODS WILL BE THE MOST ACTIVE...AS PULSES OF ENERGY MOVE FROM WEST TO EAST ALONG THE NEARLY STATIONARY BOUNDARY DURING THE AFTERNOON AND EVENING PEAK HEATING HOURS. SHOWERS AND THUNDERSTORMS WILL BE WIDESPREAD AND COULD BRING LOCALLY HEAVY RAINFALL TO SOME LOCATIONS...PARTICULARLY SUNDAY THROUGH TUESDAY. THE TROUGH WILL FINALLY PUSH EASTWARD AND OUT OF THE REGION BY THE END OF THE WEEK...AS THE UPPER PARENT TROUGH IS DISPLACED BY A LARGE AREA OF CANADIAN HIGH PRESSURE MIDWEEK ONWARD. TEMPERATURES SUNDAY THROUGH WEDNESDAY WILL LIKELY RUN A BIT BELOW NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION EXPECTED TO AFFECT THE AREA. THE END OF THE NEW WORK WEEK WILL SEE A WARM UP TO MORE NORMAL SUMMERTIME TEMPERATURES...AS A RIDGE OF HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 750 AM EDT FRI JUL 19 2013 FOG WILL CONTINUE TO LIFT AND DISSIPATE THROUGH ABOUT 13Z. INITIALLY FOG WILL BE BELOW AIRPORT MINS AT JKL AND IN THE IFR RANGE AT LOZ...WITH THIS IMPROVING BY 13Z. DIURNALLY DRIVEN CONVECTION SHOULD DEVELOP AFTER 16Z...BUT DECREASE IN COVERAGE BY THE 0Z TO 3Z PERIOD. SOME MVFR OR LOWER FOG WILL BE POSSIBLE IN ALL AREAS FROM ABOUT 6Z ON ONCE AGAIN...ESPECIALLY WHERE CONVECTION OCCURS LATER TODAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JP LONG TERM...AR AVIATION...JP
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
750 AM EDT FRI JUL 19 2013 .UPDATE... ISSUED AT 745 AM EDT FRI JUL 19 2013 FOG CONTINUES TO LIFT UP TO THE RIDGETOP LEVEL IN SOUTHEASTERN KY. K22... JKL AND I35 ARE CURRENTLY EXPERIENCING DENSE FOG. THIS SHOULD LIFT AND DISSIPATE BY AROUND 9 AM. THE HWO...ZFP AND GRIDS ALREADY HAD A HANDLE ON THIS. HOURLY TEMPS AND DEWPOINTS WERE FRESHENED UP BASED ON RECENT OBS. OVERALL...THE FORECAST REMAINS ON TRACK. THE 6Z NAM AND MOST RECENT HRRR RUN APPEAR TO DEVELOP CONVECTION TOO QUICKLY AND BOTH HAVE CONVECTION NEAR THE OH RIVER THAT IS NOT OCCURRING. HOWEVER...DIURNALLY DRIVEN SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...AFTER 16Z. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 325 AM EDT FRI JUL 19 2013 EARLY THIS MORNING...A RIDGE OF HIGH PRESSURE WAS LOCATED OVER THE WESTERN CONUS WITH ANOTHER RIDGE CENTERED OVER VA WITH A BIT OF A WEAKNESS IN BETWEEN. MEANWHILE A CLOSED UPPER LEVEL LOW WAS OVER THE HUDSON BAY REGION IN CENTRAL CANADA. A SERIES OF UPPER LEVEL DISTURBANCES WERE MOVING THROUGH THE WESTERLIES NEAR THE US/CANADIAN BORDER. ONE SHORTWAVE IN PARTICULAR EXTENDED FROM WESTERN ONTARIO DOWN INTO THE NORTHERN PLAINS/UPPER MS VALLEY REGION AND WAS APPROACHING THE WESTERN GREAT LAKES REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS OVER NORTHERN ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST INTO THE UPPER MS VALLEY AND NORTHERN GREAT LAKES REGION. LOCALLY...TEMPS ARE RATHER MILD EVEN FOR JULY WITH MOST LOCATIONS CURRENTLY IN THE LOW TO MID 70S. PATCHY DENSE FOG HAS ALSO FORMED MAINLY IN THE VALLEYS. THROUGH AN HOUR OR TWO PAST DAWN...PATCHY DENSE RIVER VALLEY FOG SHOULD GRADUALLY LIFT AND DISSIPATE. THIS WILL CONTINUE TO BE INCLUDED IN THE HWO AND A PREFIRST PERIOD WILL PROBABLY BE USED TO COVER THIS AS WELL. THROUGH THE PERIOD...THE UPPER LEVEL LOW AND LEAD SHORTWAVE WILL ROTATE THROUGH THE GREAT LAKES REGION AND ONTARIO INTO QUEBEC RESPECTIVELY AS THE UPPER LEVEL RIDGE NOW OVER VA WEAKENS AND SHIFTS OFF THE SOUTHEASTERN US COAST AND INTO THE ATLANTIC WITH RIDGING REMAINING OVER THE WESTERN CONUS. THIS COMBINATION WILL LEAD TO A BROAD TROUGH BEING CARVED OUT OVER MUCH OF EASTERN CANADA SOUTH INTO MUCH OF THE EASTERN CONUS. ALTHOUGH THE ASSOCIATED COLD FRONT WILL BECOME INCREASINGLY SHEARED WITH TIME...IT IS EXPECTED TO MOVE THROUGH THE GREAT LAKES AND MUCH OF NEW ENGLAND BY THE END OF THE PERIOD WITH THE TRAILING PORTION OF THE FRONT BECOMINGLY INCREASINGLY WEST TO EAST ORIENTED AS IT APPROACHES THE OH RIVER VALLEY REGION. THIS COLD FRONT AS SHORTWAVES MOVING THROUGH THE FLOW WILL BECOME A FOCUS FOR CONVECTION IN THE OH VALLEY LATE IN THE PERIOD. UNTIL THEN...THE SOURCES FOR FOCUSING CONVECTION OTHER THAN A GRADUAL DECREASE IN HEIGHTS AND ANY LEFTOVER BOUNDARIES FROM CONVECTION IN FRI AS WELL AS DAYTIME HEATING ARE HARD TO DETERMINE. WITH MINIMAL SHEAR AND MODERATE INSTABILITY EXPECTED TODAY...CONVECTION SHOULD BE SCATTERED IN NATURE. A DECREASE IN CONVECTION IS EXPECTED TONIGHT WITH LOSS OF DAYTIME HEATING. TEMPERATURES TODAY WILL BE LARGELY DETERMINED BY TIMING OF DEVELOPMENT OF CU AND ANY SHRA OR TSRA. THE MAV MOS IS LIKELY TOO WARM AS IT WAS YESTERDAY BUT THE COOLER MET NUMBERS ARE PROBABLY DUE TO ITS CONVECTION EARLIER IN THE DAY WHICH SEEMS A BIT SUSPECT. OVERALL..A COMPROMISE OF THE INHERITED FORECAST AND A BLEND OF THE MODEL GUIDANCE WAS USED FOR DAYTIME HEIGHT`S TODAY. DEWPOINTS ARE EXPECTED TO REMAIN IN THE LOWER 70S AND THIS WILL LEAD TO HEAT INDEX VALUES IN THE MID TO UPPER 90S IN THE LOWER ELEVATIONS BELOW 2000 FEET AND POSSIBLY TOUCHING 100 IN A FEW SPOTS THIS AFTERNOON. THIS HAS ALREADY BEEN ADDED TO AN HWO UPDATE OVERNIGHT AND WE WILL CONSIDER AN SPS FOR THIS AS WELL. THE APPROACHING FROM AND SHORTWAVE TROUGH SHOULD LEAD TO THE GREATEST COVERAGE OF CONVECTION ON SATURDAY IN THE NORTH WITH MORE SCATTERED CONVECTION FURTHER SOUTH. GREATER CLOUD COVER SHOULD LEAD TO TEMPS ON SAT A BIT BELOW THOSE LATER TODAY. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 AM EDT FRI JUL 19 2013 THE EXTENDED WILL FEATURE A LARGE SCALE EASTERN CONUS TROUGH AND A SLOW MOVING FRONTAL BOUNDARY THAT IS PROGGED TO MEANDER ABOUT THE AREA JUST SOUTH OF THE OHIO RIVER. THE DAYTIME PERIODS WILL BE THE MOST ACTIVE...AS PULSES OF ENERGY MOVE FROM WEST TO EAST ALONG THE NEARLY STATIONARY BOUNDARY DURING THE AFTERNOON AND EVENING PEAK HEATING HOURS. SHOWERS AND THUNDERSTORMS WILL BE WIDESPREAD AND COULD BRING LOCALLY HEAVY RAINFALL TO SOME LOCATIONS...PARTICULARLY SUNDAY THROUGH TUESDAY. THE TROUGH WILL FINALLY PUSH EASTWARD AND OUT OF THE REGION BY THE END OF THE WEEK...AS THE UPPER PARENT TROUGH IS DISPLACED BY A LARGE AREA OF CANADIAN HIGH PRESSURE MIDWEEK ONWARD. TEMPERATURES SUNDAY THROUGH WEDNESDAY WILL LIKELY RUN A BIT BELOW NORMAL...WITH WIDESPREAD CLOUD COVER AND PRECIPITATION EXPECTED TO AFFECT THE AREA. THE END OF THE NEW WORK WEEK WILL SEE A WARM UP TO MORE NORMAL SUMMERTIME TEMPERATURES...AS A RIDGE OF HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 750 AM EDT FRI JUL 19 2013 FOG WILL CONTINUE TO LIFT AND DISSIPATE THROUGH ABOUT 13Z. INITIALLY FOG WILL BE BELOW AIRPORT MINS AT JKL AND IN THE IFR RANGE AT LOZ...WITH THIS IMPROVING BY 13Z. DIURNALLY DRIVEN CONVECTION SHOULD DEVELOP AFTER 16Z...BUT DECREASE IN COVERAGE BY THE 0Z TO 3Z PERIOD. SOME MVFR OR LOWER FOG WILL BE POSSIBLE IN ALL AREAS FROM ABOUT 6Z ON ONCE AGAIN...ESPECIALLY WHERE CONVECTION OCCURS LATER TODAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...JP LONG TERM...AR AVIATION...JP
AREA FORECAST DISCUSSION
NWS CARIBOU ME
928 PM EDT SAT JUL 20 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE REGION OVERNIGHT. A DRIER AND COOLER CANADIAN AIR MASS WILL THEN BUILD INTO THE AREA ON SUNDAY AND HOLD OVER THE REGION THROUGH MONDAY. THE NEXT LOW PRESSURE FROM THE GREAT LAKES WILL APPROACH THE REGION LATE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH SUNDAY/... 928 PM UPDATE...A COLD FRONT ENTERING THE NORTHERN PORTION OF THE CWA WILL SWEEP ACROSS THE REMAINDER OF THE AREA TONIGHT...USHERING A MUCH DRIER AND COOLER AIR MASS ACROSS THE REGION. THE THREAT OF SEVERE WEATHER ENDED EARLIER THIS EVENING WITH NOTHING MORE THAN ISOLATED SHOWERS EXPECTED DURING THE NEXT FEW HOURS. CLEARING WILL GRADUALLY WORK INTO THE AREA IN THE WAKE OF THE COLD FRONT. UPDATED THE WX GRIDS TO REMOVE THUNDERSTORMS FOR THE REMAINDER OF THE EVENING AND UPLOADED THE PAST FEW HOURS OF OBSERVED DATA AND INTERPOLATED THROUGH THE OVERNIGHT. OVERNIGHT LOWS WERE DROPPED SEVERAL DEGREES ACROSS THE WESTERN ZONES WHERE TEMPS AT 01Z WERE RUNNING SEVERAL DEGREES ABOVE FORECAST VALUES. IT APPEARS THAT THERE WILL BE SOME MIXING AND WIND OVERNIGHT AND WITH THE LOWERING DEW POINTS DO NOT ANTICIPATE THAT THE RISK OF FOG IS GREAT AND REMOVED IT FROM THE GRIDS. UPDATE 1920 EDT: HAVE ADJUSTED POPS ...WEATHER GRIDS AND TEMPERATURES BASED ON LATEST OBSERVATIONS. PREVIOUS DISCUSSION... A COLD FRONT WILL MOVE THROUGH THE REGION OVERNIGHT FOLLOWED BY CANADIAN HIGH PRES FOR SUNDAY. THIS HIGH WILL REMAIN IN CONTROL THROUGH EARLY NEXT WEEK. SOME CONVECTION HAS FIRED UP MAINLY ACROSS NORTHERN AND WESTERN AREAS(SUB-SEVERE) AS SOME UPPER LEVEL DIVERGENCE SEEN ON THE SATL WV IMAGERY AND 12Z UA. THE BEST SHOT FOR ANY STRONGER STORMS WILL BE ACROSS THE DOWNEAST AND COAST INTO THE EVENING AND THEN ACTIVITY WILL WEAKEN. THE BEST FORCING AND INSTABILITY WILL SHIFT TO THE EAST. ADDED SOME FOG TO THE GRIDS FOR TONIGHT INTO EARLY SUNDAY MORNING BASED ON ANTICIPATED CLEARING AND COOLER TEMPERATURES W/A WET GROUND. ADJUSTED THE OVERNIGHT LOW USING A BLEND OF THE NAM12 AND ECMWF. POPS ARE A BLEND OF THE RUC AND DOWNSCALED NAM WHICH SHOW PRECIP CHANCES WINDING DOWN AFTER 00Z. SUNDAY LOOKS TO BE SUNNY AND PLEASANT W/HIGH PRES BUILDING IN FROM CANADA. THINKING ATTM IS TO TAKE W/CONSISTENCY AND KEEP THE MIDNIGHT CREW`S MAXES OF LOWER 70S NORTHERN CWA AND MID TO UPPER 70S CENTRAL AND DOWNEAST. && .SHORT TERM /SUNDAY NIGHT/... HIGH PRESSURE WILL SETTLE OVER THE AREA SUNDAY NIGHT. WITH LIGHT WINDS...CLEAR SKIES AND RELATIVELY DRY AIR THE NIGHT WILL BE COOL WITH LOWS DROPPING INTO THE 40S NORTH TO NEAR 50 DOWNEAST. THIS WILL BE FOLLOWED BY A MOSTLY SUNNY AND SEASONABLE DAY ON MONDAY. CLOUDS WILL BEGIN TO INCREASE FROM THE SOUTHWEST LATE IN THE DAY AS MOISTURE LIFTS NORTH FROM LOW PRESSURE TRACKING INTO SOUTHERN NEW ENGLAND. CLOUDS WILL CONTINUE TO INCREASE MONDAY NIGHT AND SOME RAIN MAY SPREAD INTO THE AREA LATE. THE BEST CHANCE FOR RAIN WILL BE ALONG THE FRONTAL BOUNDARY WHICH WILL BE NEAR THE COAST. THE LOW WILL TRACK JUST OFFSHORE ON TUESDAY BRINGING A CHANCE OF RAIN TO THE AREA. THE BEST CHANCE FOR RAIN WILL BE ALONG COASTAL AREAS. A COLD FRONT WILL APPROACH THE WEST LATE IN THE DAY. WARM AND HUMID AIR MOVING NORTH AHEAD OF THE FRONT BENEATH RELATIVELY COOLER AIR ALOFT MAY PRODUCE SOME THUNDERSTORMS IN WESTERN AREAS LATE IN THE DAY. && .LONG TERM /MONDAY THROUGH SATURDAY/... A WEAK LOW WILL BE TRACKING OFF THE COAST TUESDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE LOW MAY BRING SOME RAIN TO COASTAL AREAS EARLY TUESDAY NIGHT WHILE THE APPROACHING FRONT BRINGS SOME SHOWERS AND POSSIBLY THUNDERSTORMS TO FAR WESTERN AREAS. THE FRONT IS EXPECTED TO CROSS THE AREA EARLY WEDNESDAY BRINGING SOME SHOWERS AND ISOLATED THUNDERSTORMS MAINLY TO THE DOWNEAST REGION. HIGH PRESSURE SHOULD THEN BRING DRIER AIR WITH CLEARING LATER WEDNESDAY INTO THURSDAY. ANOTHER FRONT MAY APPROACH LATER FRIDAY INTO SATURDAY WITH INCREASED HUMIDITY FRIDAY INTO SATURDAY. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR THROUGH SUNDAY. SHORT TERM: VFR CONDITIONS ARE EXPECTED SUNDAY NIGHT INTO MONDAY WITH HIGH PRESSURE AND MOSTLY CLEAR SKIES. CONDITIONS WILL LIKELY BEGIN VFR MONDAY NIGHT BUT MAY LOWER TO MVFR OR IFR LATE AS LOW CLOUDS AND SHOWERS MOVE IN. MVFR CONDITIONS ARE EXPECTED TUESDAY NIGHT INTO EARLY WEDNESDAY. HIGH PRESSURE MAY THEN BRING AN IMPROVEMENT TO VFR WEDNESDAY INTO EARLY FRIDAY. LOWERING CLOUDS AND SHOWERS MAY LOWER CONDITIONS TO MVFR FRIDAY NIGHT INTO SATURDAY AS THE NEXT FRONT MOVES IN. && .MARINE... NEAR TERM: SEAS RUNNING AROUND 4 FT AT THE EASTERN MAINE SHELF THIS EVENING. WINDS ARE EXPECTED TO BECOME GUSTY W/THE COLD FRONT TONIGHT W/SPEEDS OF 25 KT BRIEFLY. THE WINDS WILL SUBSIDE ON SUNDAY DOWN TO 10 KT AS HIGH PRES PUSHES E. SHORT TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE SHOULD BRING CLEAR AND PLEASANT CONDITIONS SUNDAY INTO MONDAY. LOWER CLOUDS...FOG AND SOME RAIN MAY MOVE OVER THE WATERS ON TUESDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...CB/HEWITT/MIGNONE SHORT TERM...BLOOMER LONG TERM...BLOOMER AVIATION...CB/HEWITT/MIGNONE/BLOOMER MARINE...CB/HEWITT/MIGNONE/BLOOMER
AREA FORECAST DISCUSSION
NWS CARIBOU ME
723 PM EDT SAT JUL 20 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE REGION OVERNIGHT. A DRIER AND COOLER CANADIAN AIRMASS WILL THEN BUILD INTO THE AREA ON SUNDAY AND HOLD OVER THE REGION THROUGH MONDAY. THE NEXT LOW PRESSURE FROM THE GREAT LAKES WILL APPROACH THE REGION LATE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH SUNDAY/... UPDATE 1920 EDT: HAVE ADJUSTED POPS ...WEATHER GRIDS AND TEMPERATURES BASED ON LATEST OBSERVATIONS. A COLD FRONT WILL MOVE THROUGH THE REGION OVERNIGHT FOLLOWED BY CANADIAN HIGH PRES FOR SUNDAY. THIS HIGH WILL REMAIN IN CONTROL THROUGH EARLY NEXT WEEK. SOME CONVECTION HAS FIRED UP MAINLY ACROSS NORTHERN AND WESTERN AREAS(SUB-SEVERE) AS SOME UPPER LEVEL DIVERGENCE SEEN ON THE SATL WV IMAGERY AND 12Z UA. THE BEST SHOT FOR ANY STRONGER STORMS WILL BE ACROSS THE DOWNEAST AND COAST INTO THE EVENING AND THEN ACTIVITY WILL WEAKEN. THE BEST FORCING AND INSTABILITY WILL SHIFT TO THE EAST. ADDED SOME FOG TO THE GRIDS FOR TONIGHT INTO EARLY SUNDAY MORNING BASED ON ANTICIPATED CLEARING AND COOLER TEMPERATURES W/A WET GROUND. ADJUSTED THE OVERNIGHT LOW USING A BLEND OF THE NAM12 AND ECMWF. POPS ARE A BLEND OF THE RUC AND DOWNSCALED NAM WHICH SHOW PRECIP CHANCES WINDING DOWN AFTER 00Z. SUNDAY LOOKS TO BE SUNNY AND PLEASANT W/HIGH PRES BUILDING IN FROM CANADA. THINKING ATTM IS TO TAKE W/CONSISTENCY AND KEEP THE MIDNIGHT CREW`S MAXES OF LOWER 70S NORTHERN CWA AND MID TO UPPER 70S CENTRAL AND DOWNEAST. && .SHORT TERM /SUNDAY NIGHT/... HIGH PRESSURE WILL SETTLE OVER THE AREA SUNDAY NIGHT. WITH LIGHT WINDS...CLEAR SKIES AND RELATIVELY DRY AIR THE NIGHT WILL BE COOL WITH LOWS DROPPING INTO THE 40S NORTH TO NEAR 50 DOWNEAST. THIS WILL BE FOLLOWED BY A MOSTLY SUNNY AND SEASONABLE DAY ON MONDAY. CLOUDS WILL BEGIN TO INCREASE FROM THE SOUTHWEST LATE IN THE DAY AS MOISTURE LIFTS NORTH FROM LOW PRESSURE TRACKING INTO SOUTHERN NEW ENGLAND. CLOUDS WILL CONTINUE TO INCREASE MONDAY NIGHT AND SOME RAIN MAY SPREAD INTO THE AREA LATE. THE BEST CHANCE FOR RAIN WILL BE ALONG THE FRONTAL BOUNDARY WHICH WILL BE NEAR THE COAST. THE LOW WILL TRACK JUST OFFSHORE ON TUESDAY BRINGING A CHANCE OF RAIN TO THE AREA. THE BEST CHANCE FOR RAIN WILL BE ALONG COASTAL AREAS. A COLD FRONT WILL APPROACH THE WEST LATE IN THE DAY. WARM AND HUMID AIR MOVING NORTH AHEAD OF THE FRONT BENEATH RELATIVELY COOLER AIR ALOFT MAY PRODUCE SOME THUNDERSTORMS IN WESTERN AREAS LATE IN THE DAY. && .LONG TERM /MONDAY THROUGH SATURDAY/... A WEAK LOW WILL BE TRACKING OFF THE COAST TUESDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE LOW MAY BRING SOME RAIN TO COASTAL AREAS EARLY TUESDAY NIGHT WHILE THE APPROACHING FRONT BRINGS SOME SHOWERS AND POSSIBLY THUNDERSTORMS TO FAR WESTERN AREAS. THE FRONT IS EXPECTED TO CROSS THE AREA EARLY WEDNESDAY BRINGING SOME SHOWERS AND ISOLATED THUNDERSTORMS MAINLY TO THE DOWNEAST REGION. HIGH PRESSURE SHOULD THEN BRING DRIER AIR WITH CLEARING LATER WEDNESDAY INTO THURSDAY. ANOTHER FRONT MAY APPROACH LATER FRIDAY INTO SATURDAY WITH INCREASED HUMIDITY FRIDAY INTO SATURDAY. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... NEAR TERM: UNSETTLED CONDITIONS THROUGH AT THE START OF THE PERIOD. MVFR NORTH...BECMG VFR EARLY EVENING. A BRIEF PERIOD OF MVFR AND PERHAPS IFR FOR KBHB/KBGR THROUGH TONIGHT IN SHRA/TSRA AND SOME FOG. VFR ALL SITES ON SUNDAY. SHORT TERM: VFR CONDITIONS ARE EXPECTED SUNDAY NIGHT INTO MONDAY WITH HIGH PRESSURE AND MOSTLY CLEAR SKIES. CONDITIONS WILL LIKELY BEGIN VFR MONDAY NIGHT BUT MAY LOWER TO MVFR OR IFR LATE AS LOW CLOUDS AND SHOWERS MOVE IN. MVFR CONDITIONS ARE EXPECTED TUESDAY NIGHT INTO EARLY WEDNESDAY. HIGH PRESSURE MAY THEN BRING AN IMPROVEMENT TO VFR WEDNESDAY INTO EARLY FRIDAY. LOWERING CLOUDS AND SHOWERS MAY LOWER CONDITIONS TO MVFR FRIDAY NIGHT INTO SATURDAY AS THE NEXT FRONT MOVES IN. && .MARINE... NEAR TERM: SEAS 3-5 FT ATTM. WAVE GUIDANCE INCLUDING THE SWAN RUNNING TOO HIGH AS THE LATEST OBS SHOWED NO MORE THAN 4 FT(44027). WINDS ARE EXPECTED TO BECOME GUSTY W/THE COLD FRONT TONIGHT W/SPEEDS OF 25 KT BRIEFLY. THE WINDS WILL SUBSIDE ON SUNDAY DOWN TO 10 KT AS HIGH PRES PUSHES E. SHORT TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE SHOULD BRING CLEAR AND PLEASANT CONDITIONS SUNDAY INTO MONDAY. LOWER CLOUDS...FOG AND SOME RAIN MAY MOVE OVER THE WATERS ON TUESDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...MIGNONE
AREA FORECAST DISCUSSION
NWS GRAY ME
644 PM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID WEATHER WILL CONTINUE THIS EVENING ALONG WITH THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS...ESPECIALLY ACROSS NORTHERN AREAS WHERE A SEVERE THUNDERSTORM WATCH IS IN EFFECT THROUGH 11 PM THIS EVENING. OTHERWISE VERY WARM AND MUGGY WEATHER AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE OFF THE COAST SATURDAY NIGHT WITH ANOTHER CHANCE OF STRONG TO SEVERE THUNDERSTORMS DURING THE DAY SATURDAY. HIGH PRESSURE FOLLOWS THE FRONT BRINGING COOLER AND LESS HUMID AIR TO THE REGION WHICH WILL END OUR HEAT WAVE. THE HIGH WILL HOLD ON THROUGH TUESDAY. WEAK LOW PRESSURE WILL MOVE THROUGH SOUTHERN NEW ENGLAND TUESDAY NIGHT AND WEDNESDAY...PROVIDING THE NEXT CHANCE OF SHOWERS OR THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WILL UPDATE TO ADJUST CHANCE OF SHOWERS AND THUNDERSTORMS BASED ON LATEST RADAR. RADAR SHOWING LINE OF STRONG/SEVERE THUNDERSTORMS MOVING THROUGH OUR NORTHERN MOST ZONES. A FEW SHOWERS JUST SOUTH OF THE LINE WITH MOST OF THE FORECAST AREA DRY AT THIS TIME. THE LINE OF STORMS WILL CONTINUE TO MOVE EAST WHILE OTHER SHOWERS AND ISOLATED TO SCATTERED THUNDERSTORMS MAKE THERE WAY INTO THE REGION LATER THIS EVENING. HAVE ADDED PATCHY VALLEY FOG LATER TONIGHT DUE TO ANY RAINFALL THAT OCCURS AND SATURATES THE BOUNDARY LAYER WHERE WE ALREADY HAVE VERY HIGH DEW POINTS. ALREADY UPDATED FORECAST TO ISSUE A SEVERE THUNDERSTORM WATCH FOR OUR NORTHERN ZONES WHICH INCLUDE COOS COUNTY IN NH AND OXFORD... FRANKLIN AND SOMERSET COUNTIES IN MAINE. THE WATCH IS IN EFFECT THROUGH 11 PM THIS EVENING. PREVIOUS DISCUSSION... HOT AND HUMID CONDITIONS ACROSS THE COASTAL PLAIN WILL GIVE WAY TO A WARM AND MUGGY NIGHT. DEW POINTS WILL ONCE AGAIN BE IN THE 70S... AND LOW TEMPERATURES WILL ONLY REACH THE LOW TO MID 70S FOR MUCH OF THE COASTAL PLAIN. THIS WILL MAKE IT DIFFICULT FOR HOT BUILDINGS THAT BAKED IN THE HEAT TODAY TO COOL OFF MUCH OVERNIGHT WITHOUT THE HELP OF AIR CONDITIONING. SHOWER AND THUNDERSTORM ACTIVITY HAS FAILED TO DEVELOP THIS AFTERNOON OVER THE FORECAST AREA... BUT EXPECT SOME DEVELOPMENT OVER THE HIGHER TERRAIN OF NEW YORK STATE AND SOUTHERN VERMONT. THIS MAY MOVE INTO SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE THIS EVENING. OTHER MORE WIDESPREAD SHOWERS AND STORMS HAVE FORMED A LINE IN SOUTHEAST ONTARIO AND SOUTHERN QUEBEC... MOVING TOWARD MONTREAL. THIS WILL LIKELY HOLD TOGETHER AND BEGIN IMPACTING FAR NORTHERN MAINE ZONES BY 6 PM. OTHER DEVELOPMENT FURTHER WEST MAY ALSO MOVE INTO THE NORTHERN PORTIONS OF THE FORECAST AREA AROUND 9 PM. THE HRRR MODEL IS ONCE AGAIN HANDLING THIS ACTIVITY QUITE WELL. DAMAGING WINDS AND HEAVY RAINFALL WILL BE A THREAT WITH THESE STORMS ESPECIALLY AS THEY FORM A LINE WITH EMBEDDED BOWING SEGMENTS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... EXPECT THE COLD FRONT TO BE PUSHING INTO NORTHERN AREAS BY SATURDAY MORNING... WITH SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF IT. MAY HAVE ACTIVITY ONGOING AT 8 AM... PROGRESSING SOUTHEAST ACROSS THE FORECAST AREA THROUGH THE AFTERNOON. THUNDERSTORM CHANCES DIMINISH THROUGH THE LATE AFTERNOON AS THE FRONT PUSHES OFFSHORE. WIND SHEAR WILL BE SUPPORTIVE FOR STORM ORGANIZATION AND A DAMAGING WIND THREAT. HIGH TEMPERATURES WILL REACH THE UPPER 80S AND LOW 90S ALONG THE COASTAL PLAIN WHERE SOME HEATING WILL OCCUR BEFORE THUNDERSTORMS ARRIVE. LINGERING HUMIDITY WILL ALLOW HEAT INDEX VALUES TO REACH THE UPPER 90S BUT SHOULD NOT REACH HEAT ADVISORY LEVELS. WITH THE COLD FRONT PUSHING OFFSHORE AND DRY HIGH PRESSURE BUILDING IN BEHIND IT... EXPECT A BREAK FROM THE HUMID WEATHER AND A RETURN TO MORE SEASONABLE TEMPERATURES. LOWS WILL REACH THE 50S AND LOW 60S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... SUNDAY WILL FINALLY BRING AN END TO THE HEAT AND HUMIDITY...WITH DEW POINTS DROPPING INTO 50S AND HIGHS IN THE 70S TO AROUND 80... UNDER MAINLY SUNNY SKIES. THE HIGH SHOULD STAY IN PLACE BENEATH MAINLY ZONAL FLOW ALOFT THROUGH TUESDAY...WITH SEASONABLE TEMPS AND RH LEVELS. MODELS SUGGESTING SEVERAL 500MB WAVES TRACKING OUT ACROSS THE GREAT LAKES TUESDAY INTO THE END OF THE WEEK...CARVING OUT A LARGER SCALE TROUGH OVER THE EASTERN THIRD OF THE CONUS. THERE WILL BE A COUPLE CHANCES FOR PRECIP AS THESE WAVES MOVE THROUGH...THE FIRST OF WHICH LOOKS TO BE TUESDAY NIGHT OR WEDNESDAY. AS THE 500 MB TROUGH DIGS TO THE WEST...WILL SEE AN INCREASE IN MOISTURE...WITH MORE HUMID CONDITIONS RETURNING MID-LATE WEEK. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM /THROUGH SATURDAY NIGHT/...SEVERE TSTM WATCH IN EFFECT THROUGH 03Z THIS EVE FOR OUR NORTHERN ZONES WHICH IMPACTS HIE. ISOLD TO SCT TSTMS COULD ALSO IMPACT REST OF FORECAST AREA OVERNIGHT...RESULTING IN GUSTY WINDS AND LOWER CIG/VSBY. PATCHY F COULD FORM OVERNIGHT ESPECIALLY WHERE RAIN FALLS...LEADING TO LOCAL IFR/LIFR. TSTMS POSSIBLE SATURDAY WITH SEVERE WX AGAIN A POSSIBILITY AS A COLD FRONT MOVES THROUGH LATER IN THE DAY. HIGH PRESSURE BUILDS IN SATURDAY NIGHT BRINGING VFR WX, WITH SOME PATCHY LATE NIGHT VALLEY F POSSIBLE, AS IT PUSHES TSTMS OUT TO SEA. LONG TERM...MAINLY VFR THROUGH WEDNESDAY. SOME VALLEY FOG WILL BE POSSIBLE SUNDAY AND MONDAY NIGHT WITH RESTRICTIONS POSSIBLE IN FOG AND COASTAL STRATUS TUESDAY NIGHT. && .MARINE... SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...WILL UPDATE TO INCREASE WINDS/GUSTS A BIT AND LOWER SEAS SOME FOR THIS EVENING BASED ON LATEST BUOY REPORTS. SMALL CRAFT ADVISORY CONTINUES FOR THE OUTER WATERS. THE PERSISTENT SOUTHWEST FLOW WILL ALLOW SEAS TO BUILD THROUGH TONIGHT... BUT MODELS TEND TO OVERDO THE WAVE HEIGHTS ON SOUTHWEST FLOW. STILL MAY SEE SOME 5 FT SEAS IN EASTERN AREAS BY MORNING. SEAS SHOULD SUBSIDE FROM SOUTHWEST TO NORTHEAST DURING THE DAY ON SATURDAY. WINDS LET UP LATE SATURDAY THEN SHIFT TO NW AS THE FRONT MOVES OFFSHORE SATURDAY NIGHT. LONG TERM...WATERS SHOULD BE QUIET SUNDAY THROUGH WEDNESDAY...WITH LIGHT WINDS...AND SEAS BELOW 5FT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MEZ012-018>021- 023-024. NH...EXCESSIVE HEAT WARNING UNTIL 7 PM EDT THIS EVENING FOR NHZ010- 013-014. HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NHZ006-008-009. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ150-152. SMALL CRAFT ADVISORY UNTIL NOON EDT SATURDAY FOR ANZ154. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
418 PM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID WEATHER WILL CONTINUE THIS EVENING ALONG WITH THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS...ESPECIALLY ACROSS NORTHERN AREAS WHERE A SEVERE THUNDERSTORM WATCH IS IN EFFECT THROUGH 11 PM THIS EVENING. OTHERWISE VERY WARM AND MUGGY WEATHER AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE OFF THE COAST SATURDAY NIGHT WITH ANOTHER CHANCE OF STRONG TO SEVERE THUNDERSTORMS DURING THE DAY SATURDAY. HIGH PRESSURE FOLLOWS THE FRONT BRINGING COOLER AND LESS HUMID AIR TO THE REGION WHICH WILL END OUR HEAT WAVE. THE HIGH WILL HOLD ON THROUGH TUESDAY. WEAK LOW PRESSURE WILL MOVE THROUGH SOUTHERN NEW ENGLAND TUESDAY NIGHT AND WEDNESDAY...PROVIDING THE NEXT CHANCE OF SHOWERS OR THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... UPDATED FORECAST TO ISSUE A SEVERE THUNDERSTORM WATCH FOR OUR NORTHERN ZONES WHICH INCLUDE COOS COUNTY IN NH AND OXFORD... FRANKLIN AND SOMERSET COUNTIES IN MAINE. THE WATCH IS IN EFFECT THROUGH 11 PM THIS EVENING. HOT AND HUMID CONDITIONS ACROSS THE COASTAL PLAIN WILL GIVE WAY TO A WARM AND MUGGY NIGHT. DEW POINTS WILL ONCE AGAIN BE IN THE 70S... AND LOW TEMPERATURES WILL ONLY REACH THE LOW TO MID 70S FOR MUCH OF THE COASTAL PLAIN. THIS WILL MAKE IT DIFFICULT FOR HOT BUILDINGS THAT BAKED IN THE HEAT TODAY TO COOL OFF MUCH OVERNIGHT WITHOUT THE HELP OF AIR CONDITIONING. SHOWER AND THUNDERSTORM ACTIVITY HAS FAILED TO DEVELOP THIS AFTERNOON OVER THE FORECAST AREA... BUT EXPECT SOME DEVELOPMENT OVER THE HIGHER TERRAIN OF NEW YORK STATE AND SOUTHERN VERMONT. THIS MAY MOVE INTO SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE THIS EVENING. OTHER MORE WIDESPREAD SHOWERS AND STORMS HAVE FORMED A LINE IN SOUTHEAST ONTARIO AND SOUTHERN QUEBEC... MOVING TOWARD MONTREAL. THIS WILL LIKELY HOLD TOGETHER AND BEGIN IMPACTING FAR NORTHERN MAINE ZONES BY 6 PM. OTHER DEVELOPMENT FURTHER WEST MAY ALSO MOVE INTO THE NORTHERN PORTIONS OF THE FORECAST AREA AROUND 9 PM. THE HRRR MODEL IS ONCE AGAIN HANDLING THIS ACTIVITY QUITE WELL. DAMAGING WINDS AND HEAVY RAINFALL WILL BE A THREAT WITH THESE STORMS ESPECIALLY AS THEY FORM A LINE WITH EMBEDDED BOWING SEGMENTS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... EXPECT THE COLD FRONT TO BE PUSHING INTO NORTHERN AREAS BY SATURDAY MORNING... WITH SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF IT. MAY HAVE ACTIVITY ONGOING AT 8 AM... PROGRESSING SOUTHEAST ACROSS THE FORECAST AREA THROUGH THE AFTERNOON. THUNDERSTORM CHANCES DIMINISH THROUGH THE LATE AFTERNOON AS THE FRONT PUSHES OFFSHORE. WIND SHEAR WILL BE SUPPORTIVE FOR STORM ORGANIZATION AND A DAMAGING WIND THREAT. HIGH TEMPERATURES WILL REACH THE UPPER 80S AND LOW 90S ALONG THE COASTAL PLAIN WHERE SOME HEATING WILL OCCUR BEFORE THUNDERSTORMS ARRIVE. LINGERING HUMIDITY WILL ALLOW HEAT INDEX VALUES TO REACH THE UPPER 90S BUT SHOULD NOT REACH HEAT ADVISORY LEVELS. WITH THE COLD FRONT PUSHING OFFSHORE AND DRY HIGH PRESSURE BUILDING IN BEHIND IT... EXPECT A BREAK FROM THE HUMID WEATHER AND A RETURN TO MORE SEASONABLE TEMPERATURES. LOWS WILL REACH THE 50S AND LOW 60S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... SUNDAY WILL FINALLY BRING AN END TO THE HEAT AND HUMIDITY...WITH DEW POINTS DROPPING INTO 50S AND HIGHS IN THE 70S TO AROUND 80... UNDER MAINLY SUNNY SKIES. THE HIGH SHOULD STAY IN PLACE BENEATH MAINLY ZONAL FLOW ALOFT THROUGH TUESDAY...WITH SEASONABLE TEMPS AND RH LEVELS. MODELS SUGGESTING SEVERAL 500MB WAVES TRACKING OUT ACROSS THE GREAT LAKES TUESDAY INTO THE END OF THE WEEK...CARVING OUT A LARGER SCALE TROUGH OVER THE EASTERN THIRD OF THE CONUS. THERE WILL BE A COUPLE CHANCES FOR PRECIP AS THESE WAVES MOVE THROUGH...THE FIRST OF WHICH LOOKS TO BE TUESDAY NIGHT OR WEDNESDAY. AS THE 500 MB TROUGH DIGS TO THE WEST...WILL SEE AN INCREASE IN MOISTURE...WITH MORE HUMID CONDITIONS RETURNING MID-LATE WEEK. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... SHORT TERM...GUSTY SOUTHWEST WINDS WILL SUBSIDE SOMEWHAT LATE THIS AFTERNOON. THUNDERSTORMS ARE POSSIBLE MAINLY THIS EVENING IN NORTHERN AREAS... THOUGH THERE COULD BE A THUNDERSTORM OR TWO OVER SOUTHERN NEW HAMPSHIRE THIS AFTERNOON. DESPITE CONTINUED HUMID WEATHER... DO NOT EXPECT FOG TONIGHT. FOG LAST NIGHT WAS DUE TO INCREASING DEW POINTS OVERNIGHT... WHILE THEY SHOULD HOLD STEADY TONIGHT WITH WINDS STAYING IN THE 5 TO 10 KNOT RANGE. THUNDERSTORMS ARE LIKELY ON SATURDAY DURING THE DAY AS A COLD FRONT MOVES THROUGH. LONG TERM...MAINLY VFR THROUGH WEDNESDAY. SOME VALLEY FOG WILL BE POSSIBLE SUNDAY AND MONDAY NIGHT WITH RESTRICTIONS POSSIBLE IN FOG AND COASTAL STRATUS TUESDAY NIGHT. && .MARINE... SHORT TERM...SMALL CRAFT ADVISORY CONTINUES FOR THE OUTER WATERS. ALTHOUGH 850 MB WIND SPEEDS ARE 30 TO 35 KNOTS... THE INVERSION THAT LIKELY EXISTS OVER THE COOLER WATERS IN THIS ENVIRONMENT WILL PREVENT WIND GUSTS FROM GETTING MUCH ABOVE 20 TO 25 KT. THE PERSISTENT SOUTHWEST FLOW WILL ALLOW SEAS TO BUILD THROUGH TONIGHT... BUT MODELS TEND TO OVERDO THE WAVE HEIGHTS ON SOUTHWEST FLOW. STILL MAY SEE SOME 5 FT SEAS IN EASTERN AREAS BY MORNING. SEAS SHOULD SUBSIDE FROM SOUTHWEST TO NORTHEAST DURING THE DAY ON SATURDAY. LONG TERM...WATERS SHOULD BE QUIET SUNDAY THROUGH WEDNESDAY...WITH LIGHT WINDS...AND SEAS BELOW 5FT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MEZ012-018>021- 023-024. NH...EXCESSIVE HEAT WARNING UNTIL 7 PM EDT THIS EVENING FOR NHZ010- 013-014. HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NHZ006-008-009. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ150-152. SMALL CRAFT ADVISORY UNTIL NOON EDT SATURDAY FOR ANZ154. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
415 PM EDT FRI JUL 19 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION ON SATURDAY...PRODUCING POTENTIALLY SEVERE STORMS. BEHIND THIS FRONT...COOLER AND LESS HUMID HIGH PRESSURE WILL BUILD IN...BRINGING AN END TO OUR HEAT WAVE. THIS HIGH HOLD FOR SUNDAY THROUGH TUESDAY...WITH HIGHS IN THE 70S TO LOW 80S...AND OVERNIGHT LOWS IN THE 50S TO AROUND 60. WEAK LOW PRESSURE WILL MOVE THROUGH SOUTHERN NEW ENGLAND TUESDAY NIGHT AND WEDNESDAY...PROVIDING THE NEXT CHANCE OF SHOWERS OR THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... UPDATED FORECAST TO ISSUE A SEVERE THUNDERSTORM WATCH FOR OUR NORTHERN ZONES WHICH INCLUDE COOS COUNTY IN NH AND OXFORD... FRANKLIN AND SOMERSET COUNTIES IN MAINE. THE WATCH IS IN EFFECT THROUGH 11 PM THIS EVENING. HOT AND HUMID CONDITIONS ACROSS THE COASTAL PLAIN WILL GIVE WAY TO A WARM AND MUGGY NIGHT. DEW POINTS WILL ONCE AGAIN BE IN THE 70S... AND LOW TEMPERATURES WILL ONLY REACH THE LOW TO MID 70S FOR MUCH OF THE COASTAL PLAIN. THIS WILL MAKE IT DIFFICULT FOR HOT BUILDINGS THAT BAKED IN THE HEAT TODAY TO COOL OFF MUCH OVERNIGHT WITHOUT THE HELP OF AIR CONDITIONING. SHOWER AND THUNDERSTORM ACTIVITY HAS FAILED TO DEVELOP THIS AFTERNOON OVER THE FORECAST AREA... BUT EXPECT SOME DEVELOPMENT OVER THE HIGHER TERRAIN OF NEW YORK STATE AND SOUTHERN VERMONT. THIS MAY MOVE INTO SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE THIS EVENING. OTHER MORE WIDESPREAD SHOWERS AND STORMS HAVE FORMED A LINE IN SOUTHEAST ONTARIO AND SOUTHERN QUEBEC... MOVING TOWARD MONTREAL. THIS WILL LIKELY HOLD TOGETHER AND BEGIN IMPACTING FAR NORTHERN MAINE ZONES BY 6 PM. OTHER DEVELOPMENT FURTHER WEST MAY ALSO MOVE INTO THE NORTHERN PORTIONS OF THE FORECAST AREA AROUND 9 PM. THE HRRR MODEL IS ONCE AGAIN HANDLING THIS ACTIVITY QUITE WELL. DAMAGING WINDS AND HEAVY RAINFALL WILL BE A THREAT WITH THESE STORMS ESPECIALLY AS THEY FORM A LINE WITH EMBEDDED BOWING SEGMENTS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... EXPECT THE COLD FRONT TO BE PUSHING INTO NORTHERN AREAS BY SATURDAY MORNING... WITH SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF IT. MAY HAVE ACTIVITY ONGOING AT 8 AM... PROGRESSING SOUTHEAST ACROSS THE FORECAST AREA THROUGH THE AFTERNOON. THUNDERSTORM CHANCES DIMINISH THROUGH THE LATE AFTERNOON AS THE FRONT PUSHES OFFSHORE. WIND SHEAR WILL BE SUPPORTIVE FOR STORM ORGANIZATION AND A DAMAGING WIND THREAT. HIGH TEMPERATURES WILL REACH THE UPPER 80S AND LOW 90S ALONG THE COASTAL PLAIN WHERE SOME HEATING WILL OCCUR BEFORE THUNDERSTORMS ARRIVE. LINGERING HUMIDITY WILL ALLOW HEAT INDEX VALUES TO REACH THE UPPER 90S BUT SHOULD NOT REACH HEAT ADVISORY LEVELS. WITH THE COLD FRONT PUSHING OFFSHORE AND DRY HIGH PRESSURE BUILDING IN BEHIND IT... EXPECT A BREAK FROM THE HUMID WEATHER AND A RETURN TO MORE SEASONABLE TEMPERATURES. LOWS WILL REACH THE 50S AND LOW 60S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... SUNDAY WILL FINALLY BRING AN END TO THE HEAT AND HUMIDITY...WITH DEW POINTS DROPPING INTO 50S AND HIGHS IN THE 70S TO AROUND 80... UNDER MAINLY SUNNY SKIES. THE HIGH SHOULD STAY IN PLACE BENEATH MAINLY ZONAL FLOW ALOFT THROUGH TUESDAY...WITH SEASONABLE TEMPS AND RH LEVELS. MODELS SUGGESTING SEVERAL 500MB WAVES TRACKING OUT ACROSS THE GREAT LAKES TUESDAY INTO THE END OF THE WEEK...CARVING OUT A LARGER SCALE TROUGH OVER THE EASTERN THIRD OF THE CONUS. THERE WILL BE A COUPLE CHANCES FOR PRECIP AS THESE WAVES MOVE THROUGH...THE FIRST OF WHICH LOOKS TO BE TUESDAY NIGHT OR WEDNESDAY. AS THE 500 MB TROUGH DIGS TO THE WEST...WILL SEE AN INCREASE IN MOISTURE...WITH MORE HUMID CONDITIONS RETURNING MID-LATE WEEK. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... SHORT TERM...GUSTY SOUTHWEST WINDS WILL SUBSIDE SOMEWHAT LATE THIS AFTERNOON. THUNDERSTORMS ARE POSSIBLE MAINLY THIS EVENING IN NORTHERN AREAS... THOUGH THERE COULD BE A THUNDERSTORM OR TWO OVER SOUTHERN NEW HAMPSHIRE THIS AFTERNOON. DESPITE CONTINUED HUMID WEATHER... DO NOT EXPECT FOG TONIGHT. FOG LAST NIGHT WAS DUE TO INCREASING DEW POINTS OVERNIGHT... WHILE THEY SHOULD HOLD STEADY TONIGHT WITH WINDS STAYING IN THE 5 TO 10 KNOT RANGE. THUNDERSTORMS ARE LIKELY ON SATURDAY DURING THE DAY AS A COLD FRONT MOVES THROUGH. LONG TERM...MAINLY VFR THROUGH WEDNESDAY. SOME VALLEY FOG WILL BE POSSIBLE SUNDAY AND MONDAY NIGHT WITH RESTRICTIONS POSSIBLE IN FOG AND COASTAL STRATUS TUESDAY NIGHT. && .MARINE... SHORT TERM...SMALL CRAFT ADVISORY CONTINUES FOR THE OUTER WATERS. ALTHOUGH 850 MB WIND SPEEDS ARE 30 TO 35 KNOTS... THE INVERSION THAT LIKELY EXISTS OVER THE COOLER WATERS IN THIS ENVIRONMENT WILL PREVENT WIND GUSTS FROM GETTING MUCH ABOVE 20 TO 25 KT. THE PERSISTENT SOUTHWEST FLOW WILL ALLOW SEAS TO BUILD THROUGH TONIGHT... BUT MODELS TEND TO OVERDO THE WAVE HEIGHTS ON SOUTHWEST FLOW. STILL MAY SEE SOME 5 FT SEAS IN EASTERN AREAS BY MORNING. SEAS SHOULD SUBSIDE FROM SOUTHWEST TO NORTHEAST DURING THE DAY ON SATURDAY. LONG TERM...WATERS SHOULD BE QUIET SUNDAY THROUGH WEDNESDAY...WITH LIGHT WINDS...AND SEAS BELOW 5FT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MEZ012-018>021- 023-024. NH...EXCESSIVE HEAT WARNING UNTIL 7 PM EDT THIS EVENING FOR NHZ010- 013-014. HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NHZ006-008-009. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ150-152. SMALL CRAFT ADVISORY UNTIL NOON EDT SATURDAY FOR ANZ154. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
319 PM EDT FRI JUL 19 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION ON SATURDAY...PRODUCING POTENTIALLY SEVERE STORMS. BEHIND THIS FRONT...COOLER AND LESS HUMID HIGH PRESSURE WILL BUILD IN...BRINGING AN END TO OUR HEAT WAVE. THIS HIGH HOLD FOR SUNDAY THROUGH TUESDAY...WITH HIGHS IN THE 70S TO LOW 80S...AND OVERNIGHT LOWS IN THE 50S TO AROUND 60. WEAK LOW PRESSURE WILL MOVE THROUGH SOUTHERN NEW ENGLAND TUESDAY NIGHT AND WEDNESDAY...PROVIDING THE NEXT CHANCE OF SHOWERS OR THUNDERSTORMS. && .NEAR TERM /TONIGHT/... HOT AND HUMID CONDITIONS ACROSS THE COASTAL PLAIN WILL GIVE WAY TO A WARM AND MUGGY NIGHT. DEW POINTS WILL ONCE AGAIN BE IN THE 70S... AND LOW TEMPERATURES WILL ONLY REACH THE LOW TO MID 70S FOR MUCH OF THE COASTAL PLAIN. THIS WILL MAKE IT DIFFICULT FOR HOT BUILDINGS THAT BAKED IN THE HEAT TODAY TO COOL OFF MUCH OVERNIGHT WITHOUT THE HELP OF AIR CONDITIONING. SHOWER AND THUNDERSTORM ACTIVITY HAS FAILED TO DEVELOP THIS AFTERNOON OVER THE FORECAST AREA... BUT EXPECT SOME DEVELOPMENT OVER THE HIGHER TERRAIN OF NEW YORK STATE AND SOUTHERN VERMONT. THIS MAY MOVE INTO SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE THIS EVENING. OTHER MORE WIDESPREAD SHOWERS AND STORMS HAVE FORMED A LINE IN SOUTHEAST ONTARIO AND SOUTHERN QUEBEC... MOVING TOWARD MONTREAL. THIS WILL LIKELY HOLD TOGETHER AND BEGIN IMPACTING FAR NORTHERN MAINE ZONES BY 6 PM. OTHER DEVELOPMENT FURTHER WEST MAY ALSO MOVE INTO THE NORTHERN PORTIONS OF THE FORECAST AREA AROUND 9 PM. THE HRRR MODEL IS ONCE AGAIN HANDLING THIS ACTIVITY QUITE WELL. DAMAGING WINDS AND HEAVY RAINFALL WILL BE A THREAT WITH THESE STORMS ESPECIALLY AS THEY FORM A LINE WITH EMBEDDED BOWING SEGMENTS. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... EXPECT THE COLD FRONT TO BE PUSHING INTO NORTHERN AREAS BY SATURDAY MORNING... WITH SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF IT. MAY HAVE ACTIVITY ONGOING AT 8 AM... PROGRESSING SOUTHEAST ACROSS THE FORECAST AREA THROUGH THE AFTERNOON. THUNDERSTORM CHANCES DIMINISH THROUGH THE LATE AFTERNOON AS THE FRONT PUSHES OFFSHORE. WIND SHEAR WILL BE SUPPORTIVE FOR STORM ORGANIZATION AND A DAMAGING WIND THREAT. HIGH TEMPERATURES WILL REACH THE UPPER 80S AND LOW 90S ALONG THE COASTAL PLAIN WHERE SOME HEATING WILL OCCUR BEFORE THUNDERSTORMS ARRIVE. LINGERING HUMIDITY WILL ALLOW HEAT INDEX VALUES TO REACH THE UPPER 90S BUT SHOULD NOT REACH HEAT ADVISORY LEVELS. WITH THE COLD FRONT PUSHING OFFSHORE AND DRY HIGH PRESSURE BUILDING IN BEHIND IT... EXPECT A BREAK FROM THE HUMID WEATHER AND A RETURN TO MORE SEASONABLE TEMPERATURES. LOWS WILL REACH THE 50S AND LOW 60S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... SUNDAY WILL FINALLY BRING AN END TO THE HEAT AND HUMIDITY...WITH DEW POINTS DROPPING INTO 50S AND HIGHS IN THE 70S TO AROUND 80... UNDER MAINLY SUNNY SKIES. THE HIGH SHOULD STAY IN PLACE BENEATH MAINLY ZONAL FLOW ALOFT THROUGH TUESDAY...WITH SEASONABLE TEMPS AND RH LEVELS. MODELS SUGGESTING SEVERAL 500MB WAVES TRACKING OUT ACROSS THE GREAT LAKES TUESDAY INTO THE END OF THE WEEK...CARVING OUT A LARGER SCALE TROUGH OVER THE EASTERN THIRD OF THE CONUS. THERE WILL BE A COUPLE CHANCES FOR PRECIP AS THESE WAVES MOVE THROUGH...THE FIRST OF WHICH LOOKS TO BE TUESDAY NIGHT OR WEDNESDAY. AS THE 500 MB TROUGH DIGS TO THE WEST...WILL SEE AN INCREASE IN MOISTURE...WITH MORE HUMID CONDITIONS RETURNING MID-LATE WEEK. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... SHORT TERM...GUSTY SOUTHWEST WINDS WILL SUBSIDE SOMEWHAT LATE THIS AFTERNOON. THUNDERSTORMS ARE POSSIBLE MAINLY THIS EVENING IN NORTHERN AREAS... THOUGH THERE COULD BE A THUNDERSTORM OR TWO OVER SOUTHERN NEW HAMPSHIRE THIS AFTERNOON. DESPITE CONTINUED HUMID WEATHER... DO NOT EXPECT FOG TONIGHT. FOG LAST NIGHT WAS DUE TO INCREASING DEW POINTS OVERNIGHT... WHILE THEY SHOULD HOLD STEADY TONIGHT WITH WINDS STAYING IN THE 5 TO 10 KNOT RANGE. THUNDERSTORMS ARE LIKELY ON SATURDAY DURING THE DAY AS A COLD FRONT MOVES THROUGH. LONG TERM...MAINLY VFR THROUGH WEDNESDAY. SOME VALLEY FOG WILL BE POSSIBLE SUNDAY AND MONDAY NIGHT WITH RESTRICTIONS POSSIBLE IN FOG AND COASTAL STRATUS TUESDAY NIGHT. && .MARINE... SHORT TERM...SMALL CRAFT ADVISORY CONTINUES FOR THE OUTER WATERS. ALTHOUGH 850 MB WIND SPEEDS ARE 30 TO 35 KNOTS... THE INVERSION THAT LIKELY EXISTS OVER THE COOLER WATERS IN THIS ENVIRONMENT WILL PREVENT WIND GUSTS FROM GETTING MUCH ABOVE 20 TO 25 KT. THE PERSISTENT SOUTHWEST FLOW WILL ALLOW SEAS TO BUILD THROUGH TONIGHT... BUT MODELS TEND TO OVERDO THE WAVE HEIGHTS ON SOUTHWEST FLOW. STILL MAY SEE SOME 5 FT SEAS IN EASTERN AREAS BY MORNING. SEAS SHOULD SUBSIDE FROM SOUTHWEST TO NORTHEAST DURING THE DAY ON SATURDAY. LONG TERM...WATERS SHOULD BE QUIET SUNDAY THROUGH WEDNESDAY...WITH LIGHT WINDS...AND SEAS BELOW 5FT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MEZ012-018>021- 023-024. NH...EXCESSIVE HEAT WARNING UNTIL 7 PM EDT THIS EVENING FOR NHZ010- 013-014. HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NHZ006-008-009. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ150-152. SMALL CRAFT ADVISORY UNTIL NOON EDT SATURDAY FOR ANZ154. && $$ SYNOPSIS...CEMPA NEAR TERM...KIMBLE SHORT TERM...KIMBLE LONG TERM...CEMPA AVIATION...CEMPA/KIMBLE MARINE...CEMPA/KIMBLE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
715 PM EDT SAT JUL 20 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 419 PM EDT SAT JUL 20 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NE CANADA AND A WEAK RIDGE INTO MANITOBA RESULTING IN CONFLUENT WNW FLOW THROUGH THE NRN GREAT LAKES. AT THE SFC...A RIDGE EXTENDED FROM SRN MANTIOBA INTO NW ONTARIO TO NW LAKE SUPERIOR. ABUNDANT DIRUNAL CU HAD DEVELOPED IN THE COOL AIR TO THE NORTH OF LAKE SUPERIOR WHERE 850 MB TEMPS WERE DOWN TO 2C-3C. FARTHER SOUTH...VIS LOOP SHOWED ONLY SCT CU OVER THE W HALF OF UPPER MI. TONIGHT...WITH CLEAR SKIES AND LIGHT WINDS TONIGHT...FAVORABLE RADIATIONAL COOLING CONDITIONS IN THE DRY AIRMASS OVER THE REGION (PWAT BELOW 0.50 INCH)WILL ALLOW TEMPS TO DROP TO NEAR THE LOW END OF GUIDANCE...NEAR 40 OVER THE COLDER INLAND LOCATIONS. SUN...AS THE SFC HIGH SHIFTS EAST OF THE AREA AND THE MID LEVEL FLOW BECOMES MORE ZONAL...SRLY FLOW AND WAA WILL INCREASE AHEAD OF APPROACHING SHORTWAVE AND FRONTAL SYSTEM OVER THE NRN PLAINS. TEMPS SHOULD CLIMB INTO THE LOWER TO MID 70S INLAND WITH LOWER READINGS IN THE MID TO UPPER 60S ALONG THE GREAT LAKES. MODELS SUGGEST THAT THE GREATEST INCREASE IN MOISTURE AND STRONGER 300-310K ISENTROPIC LIFT WILL REMAIN TO THE SOUTH AND WEST OF UPPER MI FROM SRN MN INTO CNTRL WI LATE SUN AFTERNOON. SO...THE FCST MAINTAINS ONLY SLIGHT CHANCE POPS INTO THE FAR WEST .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 419 PM EDT SAT JUL 20 2013 UPPER AIR PATTERN THROUGH NEXT WEEK DRIVEN BY TWO AREAS OF LOWER HEIGHTS...ONE OVER GULF OF ALASKA/BRITISH COLUMBIA AND THE OTHER VCNTY OF HUDSON BAY ACROSS QUEBEC. IN BTWN THESE TWO...WNW FLOW HOLDS IN PLACE FROM WESTERN CANADA ACROSS GREAT LAKES. MOST PERSISTENT RIDGING WILL BE LIMITED TO SOUTHWEST PART OF CONUS. PATTERN DOES NOT LOOK APPRECIABLY WARM...ESPECIALLY COMPARED TO THE RECENT HEAT WAVE THAT AFFECTED GREAT LAKES REGION. OVERALL TEMPS THROUGH THE PERIOD WILL BE AT OR SLIGHTLY BLO NORMAL /NORMAL HIGH TEMPS ON AVERAGE THIS TIME OF YEAR ARE IN THE UPR 70S NORTH TO LOWER 80S SOUTH/. WARMEST DAY MOST LIKELY ON MONDAY AS WARM FRONT LIFTS ACROSS UPPER LAKES RESULTING IN SW SFC WINDS. COLD FRONT MOVES IN MONDAY NIGHT THOUGH...MAKING THIS STAY IN THE WARM SECTOR VERY BRIEF. SHRA/TSRA POSSIBLE AS THESE FRONTAL BOUNDARIES AFFECT THE AREA. ONLY OTHER CHANCE OF RAIN ARRIVES LATER THURSDAY INTO FRIDAY AS ANOTHER SFC TROUGH CROSSES THE REGION. WEAK HIGH PRESSURE AND DRY WEATHER WILL DOMINATE THE WEATHER PATTERN REST OF THE LONG TERM. FIRST FOCUS IN LONGER TERM IS SHORTWAVE PRESSING INTO SCNTRL CANADA ON SUNDAY NIGHT AND SFC LOW/TROUGH MOVING ACROSS NORTHERN PLAINS. SLIGHT H85 TEMP/MOISTURE ADVECTION OVER UPR MICHIGAN AHEAD OF THE WAVE AND SFC TROUGH...BUT INSTABILITY IS PRETTY MINIMAL WITH MUCAPES 1-6KM A FEW HUNDRED J/KG AT BEST...MAINLY OVER FAR WEST LK SUPERIOR CLOSER TO STRONGEST H85-H7 MOISTURE TRANSPORT. FCST SOUNDINGS SHOW INCREASE OF H8-H7 MOISTURE BUT HINT AT DRY AIR BLO AND ABOVE THIS LAYER. WITH LACK OF INSTABILITY AND DEEP MOISTURE AND LARGER SCALE FORCING...THINK COVERAGE TO ANY SHRA/TSRA WILL BE LIMITED SUN NIGHT BUT CANNOT COMPLETELY RULE IT OUT. SEEMS THAT BETTER CHANCES FOR SHRA/TSRA OCCUR ON MONDAY IN THE MORNING DUE TO CLOSER PROXIMITY OF SHORTWAVE/H85 TROUGH AND RESULTING SHARPER WARM AIR ADVECTION AND INCREASING H85 MOISTURE TRANSPORT. EXPECT THIS WARM AIR ADVECTION SHRA/ISOLD TSRA TO SHIFT NORTH BY AFTN ALONG SFC WARM FRONT AND THEN...PROVIDED THERE IS ENOUGH CLEARING OF MORNING CLOUDS/SHRA/TSRA...THERE SHOULD BE PERIOD OF BUILDING INSTABILITY DURING PEAK HEATING AS TEMPS WARM INTO THE UPR 70S/LWR 80S. MLCAPES TOP OUT AROUND 800-1200J/KG...HIGHEST ALONG WI BORDER. DEEP LAYER SHEAR INCREASES IN WARM SECTOR OUT AHEAD OF COLD FRONT TO 30-40 KTS AS SHORTWAVE CROSSES NORTHERN ONTARIO AND ADJACENT LK SUPERIOR. SOUNDINGS SHOW A BIT OF CAPPING AROUND H8 AND THIS ADDS UNCERTAINTY TO INITIATION. BASED ON CAPE AND SHEAR BALANCE...THERE SEEMS TO BE AT LEAST SMALL POTENTIAL FOR ISOLD SVR STORMS. SUPERCELLS POSSIBLE AS WINDS SHOW SUFFICIENT VEERING WITH HEIGHT. HAIL/WIND PRIMARY HAZARDS WITH LOWER WBZERO HEIGHTS AROUND 11KFT AND DCAPE UP TO 1000J/KG. ALL THIS IS CONDITIONAL ON HOW MUCH INSTABILITY CAN MATERIALIZE. SINCE SPC DAY 3 DID INDICATE SEE TEXT OVER THE AREA...THINK IT IS WORTH AN HWO MENTION. COLD FRONT BLOWS THROUGH CWA PRETTY QUICKLY MONDAY EVENING/EARLY OVERNIGHT. TRENDED TOWARD LOWER POPS 6Z-12Z ON TUESDAY WITH DRYING NOTED IN SOUNDINGS AND GFS/ECMWF SHOWING LITTLE IF ANY QPF IN THAT TIME FRAME THE LAST FEW MODEL RUNS. IN WAKE OF THE COLD FRONT ON TUESDAY...COULD END UP WITH NEARLY CARBON COPY OF TODAY...COOL TEMPS ALONG LK SUPERIOR/HIGHER SWIM RISK AND READINGS INTO LOWER 70S TOWARD WI BORDER. CUT GUIDANCE TEMPS FOR TUESDAY NIGHT WITH HIGH CENTER OVERHEAD. FAVORED COLD SPOTS OVER MAINLY WEST COULD REACH TO AROUND 40 DEGREES. STAYS QUIET THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE SLOWLY RETREATS. NEXT CHANCE OF RAIN RETURNS THURSDAY INTO FRIDAY. MODELS HAVING TOUGH TIME HANDLING SHORTWAVE TROUGH PUSHING THROUGH IN WNW FLOW ALOFT. LATEST GFS AND ECMWF WOULD INDICATE SHORTWAVE PASSAGE THURSDAY OR THURSDAY NIGHT. BLEND OF CONSENSUS SHOWS SLIGHT CHANCE/LOW CHANCE POPS AS ANOTHER COLD FRONT CROSSES THE AREA TIED TO THE WAVE. SATURDAY LOOKING PRETTY COOL YET AGAIN BEHIND THIS COLD FRONT. PROBABLY WILL END UP SIMILAR TO WHAT IS OCCURRING TODAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 715 PM EDT SAT JUL 20 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD AS HIGH PRESSURE REMAINS OVER THE REGION. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 419 PM EDT SAT JUL 20 2013 AS HIGH PRESSURE BUILDS INTO THE NORTHERN GREAT LAKES...WINDS WILL DIMINISH THIS EVENING TO LESS THAN 20 KNOTS. SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA ON MONDAY. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20 TO 30 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND A COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...JLA AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
548 PM EDT FRI JUL 19 2013 LATEST UPDATE... MESOSCALE DISCUSSION .MESOSCALE DISCUSSION... ISSUED AT 545 PM EDT FRI JUL 19 2013 I BELIEVE WE STILL HAVE SOME POTENTIAL FOR A LINE OF STRONG TO SEVERE STORMS TO DEVELOP JUST AHEAD OF THE COLD FRONT AS IT MOVES SLOWLY SOUTH THROUGH OUR CWA EARLY TONIGHT. CURRENTLY THERE ARE SCATTERED STORMS AHEAD OF THE FRONT OVER NORTHERN LOWER. HOWEVER THERE IS A SPEED MAX (SEEN ON THE WATER VAPOR IMAGE LOOP) OVER CNTL MN/WI AT 532 PM HEADING TOWARD NORTHERN LOWER MICHIGAN. THAT WILL BE OVER NORTHERN LOWER MICHIGAN IN THE 8 PM TO MIDNIGHT TIME FRAME. I EXPECT THE LINE TO FILL IN WITHIN THE NEXT HOUR OR TWO. THEN CONTINUE TO MOVE SOUTH SIMILAR TO THE 20Z HRRR SHOWS IT DOING. AS A RESULT I PLAN ON KEEPING OUR SEVERE THUNDERSTORM WATCH IN PLACE FOR NOW. && .SYNOPSIS... ISSUED AT 356 PM EDT FRI JUL 19 2013 A COLD FRONT WILL PRESS THROUGH SOUTHWEST LOWER MICHIGAN TONIGHT WHICH WILL BE PRECEDED BY SHOWERS AND THUNDERSTORMS. SOME OF THE STORMS THIS EVENING MAY BE SEVERE WITH DAMAGING WINDS AND TORRENTIAL RAINS. THE SHOWERS AND STORMS WILL MOVE SOUTH INTO INDIANA AND OHIO SATURDAY MORNING. A REFRESHING COOLER AND DRIER AIR MASS WILL SETTLE INTO THE STATE FOR THE WEEKEND. HIGHS WILL BE CLOSER TO NORMALS FOR THIS TIME OF YEAR WITH LOWER 80S ON SATURDAY AND AROUND 80 ON SUNDAY. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 356 PM EDT FRI JUL 19 2013 STILL A COMPLEX CONVECTIVE EVOLUTION IN PLACE...WITH A PRE FRONTAL CONVERGENCE ZONE RESULTING IN SCATTERED THUNDERSTORM DEVELOPMENT AT THIS TIME FROM NEAR HOLLAND EAST TO IONIA. THESE STORMS WILL CONTINUE TO DEVELOP AS MIXED LAYER CAPE VALUES ARE ON THE ORDER OF 2000 J/KG AT THIS TIME. TWO MAIN CORRIDORS OF INSTABILITY ARE IN PLACE ONE POOLED NEAR THE FRONT OFF TO THE NORTH WHICH STRETCHES FROM NORTHERN LAKE MICHIGAN INTO CENTRAL WISCONSIN. THE OTHER AREA OF EVEN HIGHER INSTABILITY IS NOSED INTO SOUTH CENTRAL LOWER MICHIGAN FROM GRR SOUTH AND EAST. THIS ZONE IS IN PLAY DUE TO THE FACT THAT THE SOUTHWEST FLOW IS NOT OFF THE LAKE HERE. DYNAMICS REMAIN A FACTOR AS THE MID LEVEL SHORTWAVE TROUGH EDGES IN ALONG WITH AN ENTRANCE REGION TO A 250MB JET STREAK. REALLY ALL INGREDIENTS ARE IN PLACE...MOISTURE...INSTABILITY AND LIFT. ENVISION THE CURRENT LINE CONTINUING TO DEVELOP WITH SOME SEVERE WIND GUSTS EMBEDDED. THE FRONT TO THE NORTH WILL BE THE WILD CARD BUT EXPECT TO SEE A LINEAR LINE OF STORMS FORM ALONG IT AND PROGRESS SOUTH. THESE STORMS MAY BE MOVING INTO CENTRAL LOWER MICHIGAN IN THE 7-9PM TIME RANGE. SEVERE WEATHER WITH THESE IS POSSIBLE BUT THERE IS A SOLID LAKE SHADOW OF WEAKER INSTABILITY THERE. MAIN THREAT CONTINUES TO BE DAMAGING WINDS AS STRONG SYNOPTIC SCALE FLOW IS IN PLACE IN THE 850-500MB LAYER. COOLER AND DRIER AIR WILL BRING QUIET WEATHER SATURDAY INTO SUNDAY. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 356 PM EDT FRI JUL 19 2013 COOLER PATTERN TO PERSIST WITH NEAR NORMAL TO SLIGHTLY BELOW NORMAL TEMPERATURES LOOKING MORE LIKELY THROUGH NEXT WEEK. THIS MEANS HIGHS IN THE UPPER 70S TO LOWER 80S WITH LOWS IN THE LOWER 60S. THERE WILL BE SCATTERED CHANCES FOR SHOWERS AND THUNDERSTORMS ESPECIALLY DURING THE FIRST HALF OF NEXT WEEK...BUT OVERALL NO ORGANIZED SIGNIFICANT WEATHER EXPECTED MONDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 148 PM EDT FRI JUL 19 2013 GENERALLY VFR CIGS/VSBYS EXPECTED THROUGH THE PERIOD. THERE MAY BE SHOWERS PERHAPS A TSRA IN THE VICINITY OF THE TAF SITES LATER THIS AFTERNOON. HOWEVER LATEST VIS LOOP SHOWS WEST WIND HAVE SCOURED OUT THE CU ACROSS MUCH OF THE AREA. THINK THE BETTER CHANCE OF STORMS WILL BE AFTER 10 PM WHEN THE MAIN COLD FRONT STARTS TO MOVE SOUTH ACROSS THE LOWER PENINSULA. NOT CONVINCED WE/LL SEE A SOLID LINE OF STORMS ALONG THE FRONT SO LEFT THE VCTS COMMENT IN THE TAFS. && .MARINE... ISSUED AT 356 PM EDT FRI JUL 19 2013 A COMPLEX MARINE SCENARIO IS IN PLACE WITH AN ONGOING HIGH WAVE EVENT IN PROGRESS. WAVES OF 4 TO 7 FEET ARE COMMON PLACE IN THE NEARSHORE AREA AT THIS TIME. THE WIND WILL DIMINISH TONIGHT AND THE WAVES WILL DAMPEN OUT AS WELL...SUBSIDING BELOW SMALL CRAFT ADVISORY CRITERIA AFTER MIDNIGHT. A HIGH SWIM HAZARD RISK WILL CONTINUE THROUGH SUNSET. THE COMPLICATING FACTOR IS IT APPEARS ANOTHER HIGH WAVE EVENT WILL FOLLOW QUICKLY ON THE HEELS OF THIS ONE TOMORROW AFTERNOON IN THE NORTHERLY FLOW BEHIND THE COLD FRONT. WILL HOLD OFF ON ISSUING A BEACH HAZARDS STATEMENT AND SMALL CRAFT ADVISORY FOR SATURDAY INTO SATURDAY NIGHT...LETTING THIS ONE END FIRST. A CLOSER LOOK WILL BE TAKEN AT TOMORROWS EVENT BY THE MID SHIFT. && .HYDROLOGY... ISSUED AT 356 PM EDT FRI JUL 19 2013 LOCAL FLOODING POTENTIAL WILL CONTINUE UNTIL THE FRONT AND THEREFORE STORM THREAT IS SOUTH OF THE AREA. BY SATURDAY MORNING THE FRONT SHOULD BE SOUTH OF SOUTHWEST LOWER MICHIGAN. ANY STORMS THIS EVENING AND TONIGHT GIVEN A VERY MOIST AIRMASS IN PLACE WILL BE CAPABLE OF TORRENTIAL DOWNPOURS. LOCALIZED FLOODING IS VERY POSSIBLE IN AN AIR MASS SUCH AS THIS. WIDESPREAD HEAVY AREAL RAINFALL IS NOT EXPECTED HOWEVER. SO...A FLASH FLOOD TYPE THREAT WILL EXIST THIS EVENING AND TONIGHT BUT WIDESPREAD RIVER ISSUES ARE NOT ANTICIPATED GIVEN THE LOCAL NATURE OF THE HEAVY RAINS. A COOLER AND DRIER AIR MASS WILL PUSH INTO THE AREA FOR SATURDAY AND SUNDAY. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037- 043-050-056-064-071. HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ037>040-043>046- 050>052-056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LMZ844>849. && $$ MESOSCALE...WDM SYNOPSIS...DUKE SHORT TERM...DUKE LONG TERM...MACZKO AVIATION...93 HYDROLOGY...DUKE MARINE...DUKE
AREA FORECAST DISCUSSION
NWS GAYLORD MI
132 AM EDT FRI JUL 19 2013 .SYNOPSIS... ISSUED AT 358 PM EDT THU JUL 18 2013 ONE MORE DAY OF HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS NORTHERN MICHIGAN FRIDAY BEFORE A COUPLE OF COLD FRONTS PASSING THROUGH THE GREAT LAKES WILL COOL THINGS DOWN DRAMATICALLY BY SATURDAY. PASSAGE OF THESE FRONTS WILL BE ACCOMPANIED BY THUNDERSTORM ACTIVITY...SOME OF WHICH COULD BE SEVERE OVERNIGHT AND INTO FRIDAY. THE SEVERE WEATHER THREAT WILL END BY FRIDAY EVENING...WITH A DRY AND PLEASANT WEEKEND ON TAP. && .UPDATE... ISSUED AT 113 AM EDT FRI JUL 19 2013 CHANCES FOR PRECIPITATION NEEDED UPDATING FOR TIMING/COVERAGE OF BAND OF RAIN SHOWERS AND EMBEDDED ISOLATED THUNDER (INSTABILITY REALLY LESS THAN DESIRABLE). THIS BAND WAS DROPPING THROUGH EASTERN UPPER AND WILL MAKE IT TO AND THROUGH THE STRAITS...WHILE A SECONDARY BAND OF SHOWERS BEGINS TO DROP SOUTHWARD AND BACK INTO EASTERN UPPER AND NE WISCONSIN. LESS CONFIDENCE IN THIS...AS IT MAY TAKE UNTIL THE DAYLIGHT HOURS FOR THIS TO ARRIVE. THUS...A LULL IN THE ACTION OVERNIGHT? SKY NEEDED FIXING AS WELL...WITH CLEAR SKIES ACROSS MOST OF NRN LOWER...AND THIS WILL LIKELY CONTINUE THROUGH THE NIGHT UNTIL SAID NEXT BAND OF SHOWERS/STORMS ARRIVES IN THE DAYLIGHT HOURS. UPDATE ISSUED AT 1005 PM EDT THU JUL 18 2013 SEVERE THUNDERSTORM WATCH CONTINUES LATE THIS EVENING FOR ERN UPR MICHIGAN AND THE TIP OF THE MITT. CONVECTIVE LINE (LEWP) HAS SPREAD ACROSS ALL OF ERN UPR MICHIGAN...WITH THE LEADING EDGE NOW IN THE STRAITS AREA. A FEW STORMS WITHIN THIS LINE HAVE BECOME VERY STRONG/LOW END SEVERE...BUT DID SHOW AN OVERALL DOWNWARD TREND IN INTENSITY AS IT ENTERED OUR NRN ZONES. AT THIS POINT...WILL KEEP THE WATCH GOING GIVEN THE POTENTIAL FOR A FEW ADDITIONAL STRONG/SEVERE STORMS IN RESPONSE TO STRENGTHEN WIND SHEAR AS A 45 TO 50 KT JET MAX LEANS INTO THE AREA LATE TONIGHT. WILL ALSO KEEP AN EYE ON THE NEXT LINE OF CONVECTION NOW MOVING E/SE THRU CENTRAL LAKE SUPERIOR AS WE HEAD INTO THE OVERNIGHT HOURS. UPDATE ISSUED AT 742 PM EDT THU JUL 18 2013 DIURNAL ENHANCEMENT TO CONVECTION IS QUICKLY DIMINISHING WITH THE APPROACH OF SUNSET...BRINGING AN END TO THE WIDELY SCATTERED SHOWERS AND STORMS ACROSS ALL OF NRN LWR MICHIGAN. AFTERNOON CONVECTION OVER LAKE SUPERIOR HAS FURTHER ORGANIZED INTO A LEWP... EXTENDING FROM JUST NORTH OF WHITEFISH BAY WESTWARD ALONG THE LAKE SUPERIOR SHORELINE OF CENTRAL AND ERN UPR MICHIGAN. ADDITIONAL SCATTERED SHOWERS AND STORMS HAVE DEVELOPED AHEAD OF THIS LINE OF CONVECTION...WITH THESE CELLS AND THE WHOLE LINE MOVING E/SE. THIS LINE OF CONVECTION WILL SLIDE THRU ERN UPR MICHIGAN AND THE STRAITS DURING THE BALANCE OF THE EVENING. VELOCITY DATA HAS SHOWN SOME EMBEDDED AREAS OF ROTATION WITHIN THE THE LINE...AND WILL CERTAINLY MONITOR RADAR AS THIS LINE SLIDES THRU OUR NRN CWA. OVERALL AHEAD WILL STRENGTHEN THRU THE NIGHT AS AS 45 TO 50 KT LOW LEVEL JET MAX LEANS INTO NRN MICHIGAN. PLENTY OF SURFACE BASED INSTABILITY WILL REMAIN IN TACT AS WE HEAD THRU THE NIGHT...AS WILL AMPLE 850 MB THETA E. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 358 PM EDT THU JUL 18 2013 HIGH IMPACT WEATHER POTENTIAL: ISOLATED SEVERE THUNDERSTORMS POSSIBLE THROUGH EARLY EVENING. INCREASING THREAT FOR DAMAGING WINDS TONIGHT OVER EASTERN UPPER AND THE TIP OF THE MITT...MOVING SOUTH INTO NORTHERN LOWER MICHIGAN ON FRIDAY. HOT AND HUMID WEATHER CONTINUES...WITH HEAT ADVISORIES BEING CONFINED CLOSER TO SAGINAW BAY FOR THE DAY ON FRIDAY AHEAD OF ARRIVING COLD FRONT. OVERVIEW: FLAT RIDGING CONTINUES ACROSS THE GREAT LAKES REGION THIS AFTERNOON WITH STRONGER SHORTWAVE ENERGY NOW BECOMING EVIDENT DROPPING OUT OF NORTHERN MANITOBA...WITH AN ADDITIONAL WAVE OVER SOUTHERN SASKATCHEWAN. AT THE SURFACE...LOW PRESSURE HAS TAKEN SHAPE OVER EASTERN NORTH DAKOTA THIS HOUR WITH QUASI-STATIONARY WARM FRONT EXTENDING EAST ACROSS NORTHERN MINNESOTA AND UPPER MICHIGAN. STORMS HAVE PERCOLATED ALONG THIS BOUNDARY ALL DAY GIVEN SOUPY WARM SECTOR AIRMASS AND SOUTHWESTERLY WINDS RIDING OVER THE BOUNDARY IN THE PRESENCE OF AMPLE UNCAPPED INSTABILITY AND GRADUALLY INCREASING DEEP LAYER SHEAR. ON THE MESOSCALE...AND OUTFLOW BOUNDARY WORKED SOUTH INTO NORTHERN LOWER HELPING TO TRIGGER CONVECTION SOUTH OF THE FRONT...WITH SOME OF THIS ACTIVITY ONGOING AS I TYPE. TEMPS IN AREAS NOT SEEING RAINFALL ARE NOT DISAPPOINTING THE HOT/HUMID TALK OF LATE...WITH TVC 96 AND CAD 97 THIS HOUR. THROUGH EARLY EVENING: ISOLATED TO SCATTERED TSRA ACTIVITY WILL CONTINUE OVER NORTHERN LOWER...ALTHOUGH DECREASING IN COVERAGE AS WE AWAIT FURTHER DEVELOPMENT UPSTREAM. TONIGHT: BROAD AREA OF HEIGHT FALLS OVERSPREADS THE GREAT LAKES REGION AHEAD OF STRONG SHORTWAVE WHOSE CORE WILL BE DROPPING THROUGH NORTHERN MANITOBA. BENEATH THIS FEATURE THE SURFACE LOW WILL TRACK NORTH AND EAST...TO NEAR THE SOUTHERN SHORE OF JAMES BAY BY DAYBREAK FRIDAY. HEIGHT FALLS AND TIME OF DAY WILL COAX A STRENGTHENING LLJ AT H8 FROM NORTHERN WISCONSIN NORTH AND EAST ACROSS LAKE SUPERIOR. SYNOPTIC SETUP AND SHEAR PARAMETERS CERTAINLY FAVOR PROGRESSIVE MCS DEVELOPMENT WITH OVER 30KTS OF 0-3KM BULK SHEAR...BUT NO MORE THAN 10KTS ABOVE THIS TO 6KM. THE QUESTION BECOMES...WHERE IS THIS CONVECTION LIKELY TO FORM/MOVE? THE SYNOPTICALLY-FAVORED LOCATION WOULD BE NEAR OR JUST NORTH OF LAKE SUPERIOR GIVEN THE CURRENT FRONTAL BOUNDARY AND EXPECTED LLJ LOCATION. THIS IS WELL SHOWN BY THE NEW 12Z NAM AND PROBABLY THE STRONGEST GUIDANCE CONSENSUS WHICH BRINGS TO DISTINCT CONVECTIVE COMPLEXES OVER OR NORTH OF MY NORTHERN ZONES. AFTERNOON RADAR TRENDS...HOWEVER...SUGGEST DEVELOPMENT A LITTLE FURTHER SOUTH AND WEST...OVER THE ARROWHEAD OF MINNESOTA ALONG OUTFLOW BOUNDARY IN THIS AREA. EARLY AFTERNOON HRRR IS ONTO THIS TREND...AND WITH FORWARD-PROPAGATING CORFIDI VECTORS SUGGESTING AN ESE STORM MOTION...LOOKS TO BRING ACTIVITY TOWARDS EASTERN UPPER LATER THIS EVENING...WITH PERHAPS MORE ACTIVITY DEVELOPING UPSTREAM THROUGH THE FIRST HALF OF TONIGHT AS THE LLJ STRENGTHENS IMMEDIATELY AHEAD OF THE SURFACE COLD FRONT. THUS...WILL INCREASE POPS OVER EASTERN UPPER TO LIKELY DURING THE EVENING HOURS...BUT KEEP LIKELIES PRIMARILY RESTRICTED TO EASTERN UPPER OVERNIGHT GIVEN EXPECTED STORM PROPAGATION. SOME ROGUE STORM DEVELOPMENT TO THE SOUTH IS POSSIBLE...BUT LOWER POPS WARRANTED HERE. SEVERE THREAT IS THERE...MORE ISOLATED WIND/HAIL IN THE NEAR TERM...WITH A MORE ORGANIZED WIND THREAT TAKING SHAPE THIS EVENING. REALLY LIKE INHERITED VERY WARM OVERNIGHT LOWS GIVEN INCREASING CLOUD COVER AND COUPLED BOUNDARY LAYER FLOW NOT GIVING TEMPERATURES MUCH ROOM TO FALL. SO...LOOKING LIKE THE LAST UNCOMFORTABLE SLEEPING NIGHT MAY BE THE WORST /AT LEAST OVER NORTHERN LOWER/ WHERE MID TO UPPER 70S SHOULD ABOUT DO IT. FRIDAY: SOMEWHAT UNUSUAL FOR THE APX CWA SO FAR THIS WARM SEASON...WE HAVE A COLD FRONT PROGGED TO PUSH THROUGH THE FORECAST AREA IN THE MIDDLE OF PEAK HEATING. CLEARLY...OVERNIGHT CONVECTIVE ACTIVITY WILL HAVE A HUGE IMPACT ON WHAT HAPPENS THUNDERSTORM-WISE DURING THE DAY. COULD VERY WELL BE SOME ONGOING ACTIVITY ACROSS THE CWA EARLY...WITH THE BEST CHANCES AGAIN BEING OVER EASTERN UPPER...CLOSEST TO THE ARRIVING COLD FRONT. THIS AT LEAST SPELLS THE POTENTIAL FOR SOME DESTABILIZATION AHEAD OF AFOREMENTIONED COLD FRONT /ESP OVER NORTHERN LOWER/ WHICH LOOKS TO PUSH THROUGH THE CWA IN THE 18-00Z TIME FRAME. SHEAR PARAMETERS ARE IMPRESSIVE AS THE PRIMARY BELT OF THE WESTERLIES SINKS INTO OUR AREA. 0-3KM BULK SHEAR REACHES 40KTS...WITH 50KTS+ OF 0-6KM SHEAR. SHEAR LOOKS TO ONLY HAVE A SLIGHT ANGLE TO THE ARRIVING BOUNDARY...SO A LINEAR MODE WITH EMBEDDED BOWING SEGMENTS COULD CERTAINLY BE SUPPORTED. THIS IS WELL CAPTURED BY THE DAY 2 SLIGHT RISK AREA FROM SPC. AS FOR TEMPERATURES AND HEAT ADVISORY CONCERNS...THE EARLIER EXPANSION OF THE HEAT ADVISORY TO THE SOUTHEASTERN ZONES FOR THE DAY LOOKS RIGHT ON...GIVEN STRENGTHENING SOUTHWEST WINDS GIVING SOME DOWNSLOPING ASSISTANCE TO THESE AREAS...WHICH SHOULD PUSH TEMPS INTO THE LOW/MID 90S BEFORE CONVECTIVE ACTIVITY ARRIVES FROM THE NORTH AND WEST. ELSEWHERE...LOW TO MID 80S LOOK GOOD GIVEN EXPECTED CLOUD COVER AND RAINFALL. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 358 PM EDT THU JUL 18 2013 RECENT TRENDS...TEMPERATURES: HOT...OBVIOUSLY. 1-3C ABOVE NORMAL LAST 7 DAYS AND PRETTY MUCH FOR THE MONTH OF JULY THUS FAR. PRECIPITATION/HYDROLOGY: BAND OF HEAVIER PRECIPITATION ACROSS EASTERN UPPER/STRAITS REGION LAST NIGHT (RADAR ESTIMATES 3+ INCHES FAR WESTERN MACKINAC/SCHOOLCRAFT COUNTIES) MOST SUBSTANTIAL RAINFALL OF LAST SEVEN DAYS...OUTSIDE OF SCATTERED DIURNAL ACTIVITY MUCH OF NORTHERN LOWER MICHIGAN HASN`T SEEN A DROP. 30 DAY STANDARDIZED PRECIP INDEX CONTINUING TO TREND DRIER...ESPECIALLY ACROSS PORTIONS OF UPPER MICHIGAN THAT SAW GOOD RAINS OVERNIGHT. STREAMFLOWS ON AREA RIVERS STILL MOSTLY NEAR NORMAL...HYDROGRAPHS FLAT GIVEN LACK OF RENEWED RUNOFF. TOPSOIL MOISTURE STILL IN GOOD SHAPE DESPITE RECENT DRYNESS. LARGE SCALE PATTERN/FORECAST...CONTINENTAL U.S. DOMINATED BY FLAT RIDGING...WITH THE SOUTHERN EDGE OF THE MAIN WESTERLIES RUNNING STRAIGHT WEST-EAST ALONG THE CANADIAN BORDER. PATTERN MORE BLOCKY UPSTREAM ACROSS THE PACIFIC WITH "OFF THE CHART" -EPO/-WPO INDICES. BALL OF ENERGY EMERGING FROM ABOVE THE ARCTIC CIRCLE AND ENTERING FAR NORTHERN SASKATCHEWAN/MANITOBA THIS AFTERNOON WILL BE THE CATALYST TO THE END OF THE CURRENT HEAT AND HUMIDITY THAT HAS BEEN LINGERING OVER THE UPPER LAKES THIS WEEK. STRONG HEIGHT FALLS WILL DROP ACROSS THE REGION FRIDAY AND DRIVE COOLER AIR INTO MICHIGAN FOR THE WEEKEND. QUASI-ZONAL FLOW THEN FORECAST TO SET UP ACROSS THE NORTHERN HALF OF THE CONUS FOR THE FIRST PART OF NEXT WEEK...WITH SOME LOW AMPLITUDE TROUGHING FROM THE GREAT LAKES/OHIO VALLEY NORTHEAST INTO NEW ENGLAND. AHEAD OF THE CANADIAN HEIGHT FALLS WILL BE A PAIR OF COLD FRONTS THAT WILL SWEEP ACROSS NORTHERN MICHIGAN FRIDAY/FRIDAY NIGHT. THIS WILL PUSH A REFRESHINGLY COOLER/DRIER AIR MASS INTO THE UPPER LAKES SATURDAY...WHILE HIGH PRESSURE SETTLES INTO THE REGION FOR SUNDAY. HIGH PRESSURE RETREATS TO THE EAST MONDAY WITH RETURN FLOW OF WARMER AIR BACK INTO THE UPPER MIDWEST/UPPER LAKES GETTING UNDERWAY. MAIN FORECAST CONCERN THROUGH THE WEEKEND WILL BE WITH THE TRANSITION FROM WARM/MUGGY TO COOLER WEATHER FRIDAY NIGHT. FRIDAY NIGHT THROUGH SUNDAY: WEATHER...LEAD COLD FRONT WILL LIKELY STILL BE IN THE VICINITY OF THE M-72/US-10 CORRIDOR FRIDAY EVENING...WITH CONVECTION (POTENTIALLY SEVERE) LIKELY ONGOING AHEAD OF THIS BOUNDARY WHICH SHOULD SINK INTO SOUTHERN LOWER MICHIGAN BY MIDNIGHT. SECONDARY BOUNDARY COMES IN HOT ON ITS HEELS...PUSHED ALONG BY THE MAIN SHORT WAVE TROUGH THAT WILL BE DIGGING SOUTHEAST. MUCH OF THE FORCING ALOFT LOOKS TO REMAIN NORTH OF THE FORECAST AREA...SOME QG SUBSIDENCE CROSSES NORTHERN MICHIGAN BEHIND THE LEAD FRONT. SO WILL RUN WITH THUNDERSTORM CHANCES BASICALLY SOUTH OF A MBL-APN LINE FRIDAY EVENING...AND DRY THINGS OUT THEREAFTER HEADING INTO SATURDAY. WEAK SHORT WAVE TROUGH WILL TRACK THROUGH THE MIDWEST SUNDAY...WHICH COULD PUSH CLOUDS INTO NORTHWEST LOWER DURING THE AFTERNOON HOURS. WINDS...SHIFTING TO THE NORTHWEST BEHIND SECONDARY COLD FRONT EARLY SATURDAY MORNING...WINDS WILL BE A BIT GUSTY SATURDAY GIVEN GOOD POST-FRONTAL MIXING (LOW LEVEL COLD ADVECTION/DIURNAL HEATING) ON THE ORDER OF 20+MPH. WINDS FORECAST TO SETTLE DOWN SATURDAY NIGHT AS HIGH BUILDS IN AND GRADIENT DROPS OFF. SUNDAY WINDS WILL BE LIGHT AND DOMINATED BY LAKE BREEZE EVOLUTION. TEMPERATURES...OVERNIGHT LOWS SHOULD FINALLY BREAK INTO THE 50S ACROSS EASTERN UPPER AND MUCH OF NORTHWEST/NORTH CENTRAL LOWER SATURDAY MORNING. SHOULD SEE A NICE DROP IN HUMIDITY EXPECTED SATURDAY WITH DEW POINTS FALLING INTO THE 40S DURING THE AFTERNOON. SATURDAY AFTERNOON HIGHS 65-70 EASTERN UPPER...UPPER 60S-LOWER 70S MUCH OF NORTHWEST LOWER WITH MID-UPPER 70S NORTHEAST LOWER. SEASONABLY COOL LOWS FOR SUNDAY MORNING WITH TEMPERATURES DROPPING INTO THE 40S AWAY FROM THE IMMEDIATE LAKESHORES. SUNDAY HIGHS AROUND 70-MID 70S EXPECTED. EXTENDED FORECAST (MONDAY THROUGH THURSDAY): MIDWEST SHORT WAVE CURRENTLY LOOKS AS IF IT WILL PASS SOUTH OF LOWER MICHIGAN AND INTO THE OHIO VALLEY SUNDAY NIGHT/MONDAY. IF THAT IS THE CASE THEN WILL PROBABLY START THE NEW WORK WEEK WITH A DRY FORECAST. BETTER THREAT FOR RAIN MAY ARRIVE WITH A COLD FRONT HEADING INTO THE MIDWEEK PERIOD...THEN WILL START THE NEW THURSDAY FORECAST OUT DRY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 113 AM EDT FRI JUL 19 2013 OVERALL CONDITIONS WILL REMAIN VFR THRU MOST OF THE 24 HR TAF FORECAST PERIOD...HOWEVER CHANCES OF SHOWERS AND STORMS WILL STEADILY INCREASE OVERNIGHT AND INTO FRIDAY AS A COLD FRONT DROPS SE THRU NRN MICHIGAN. LOW LEVEL SW FLOW WILL CONTINUE TO INCREASE AHEAD OF THE FRONT...LENDING TO LLWS THRU THIS MORNING. LOW LEVEL WINDS WILL BE STRONGER IN AND AROUND THUNDERSTORMS. THE COLD FRONT WILL CLEAR NRN LWR MICHIGAN BY LATE AFTERNOON...WITH MVFR CIGS DEVELOPING BEHIND THE FRONT FOR THE EVENING HOURS. && .MARINE... ISSUED AT 130 AM EDT FRI JUL 19 2013 UPDATED THE SMALL CRAFT ADVISORIES TO INCLUDE ALL OF THE NW LOWER LAKE MICHIGAN NEARSHORES....INCLUDING GRAND TRAVERSE BAY. THIS WAS ALREADY OUT...BUT TOOK OUT SEUL CHOIX TO THE BRIDGE...AND ADDED PORTIONS OF LAKE HURON NEARSHORES. GRADIENT WINDS OF 35KTS...EVEN WITH THE STABILITY...WILL LIKELY RESULT IN LOW END ADVISORY GUSTS PRIOR TO A COLD FRONTAL PASSAGE FRIDAY. IN ADDITION...GUSTY OUTFLOW FROM BAND OF SHOWER SAND ISOLATED THUNDER DROPPING INTO EASTERN UPPER WILL RESULT IN TEMPORARY ADVISORY LEVEL GUSTS. WILL HANDLE THIS WITH AN MWS. MARGINAL SCA/S MAY AGAIN BE NECESSARY ON SATURDAY GIVEN STRENGTHENING NORTHWEST FLOW. BEHIND THE FRONT FOR FRIDAY NIGHT AND SATURDAY MORNING...THE STRENGTHENING NW WINDS ARE A RESULT OF A SECONDARY COLD FRONTAL PASSAGE. HIGH PRESSURE THEN BUILDS IN FOR THE REMAINDER OF THE WEEKEND. && .APX WATCHES/WARNINGS/ADVISORIES... MI...HEAT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ016>034. HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ035-036-041-042. LH...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR LHZ349. LM...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR LMZ323-342- 344>346. LS...NONE. && $$ UPDATE...SD SYNOPSIS...JPB SHORT TERM...ARNOTT LONG TERM...JPB AVIATION...SD MARINE...ARNOTT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
203 PM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 459 AM CDT FRI JUL 19 2013 OUR MPX WRF AND HOP WRF ARE ON SIMILAR PATHS WITH THE SHOWER AND THUNDERSTORM ACTIVITY EXITING OUR AREA BY 12Z. FOR TODAY...A BREAK FROM THE HEAT AND HUMIDITY WILL BE NOTED WITH SOME SCATTERED CLOUDS...EXCEPT FOR SOUTHWEST MN WHICH MAY BE CLOUD FREE. VERY DRY AIR ABOVE 6000 FEET WILL CONTINUE WORKING ITS ITS WAY INTO WESTERN MN. THERE IS SOME LOW LEVEL MOISTURE ACROSS EASTERN MN AND WESTERN WI. THE RAP KEEPS THIS MOISTURE IN PLACE UNTIL MID AFTERNOON. SHOULD BE PLENTY OF MIXING SO DO NOT EXPECT MORE THAN SCATTERED CLOUDS...EXCEPT SW MN WHERE IT MAY BE CLEAR. MAY BE CLEAR AFTER 21Z IN MOST AREAS AS DRIER AIR FILTERS IN. OVERNIGHT A SECONDARY COLD FRONT USHERS IN COOLER AIR AND BY SATURDAY MORNING A DISTURBANCE MOVES TOWARD WESTERN MN WITH AN INCREASE IN MOISTURE. NO PRECIPITATION EXPECTED THROUGH 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 459 AM CDT FRI JUL 19 2013 THE LONG TERM PORTION OF THE FORECAST WILL FEATURE RIDGING OVER THE ROCKIES...WITH EPISODIC IMPULSES PARADING ACROSS THE NORTHERN CONUS. THE FIRST OF THESE SHORTWAVES HAS BEEN CONSISTENTLY PROGGED TO ARRIVE ON SATURDAY NIGHT INTO SUNDAY BY DETERMINISTIC AND ENSEMBLE SOLUTIONS. FAIRLY IMPRESSIVE LIFT FROM 305-310K IS PROGGED TO BLOSSOM OVER THE AREA BETWEEN 06Z AND 12Z SUNDAY AS 925-850 MOISTURE TRANSPORT NOSES INTO SOUTHERN MN. HAVE INCLUDED 50-60 POPS FOR THIS TIME FRAME. NORTHWEST FLOW PERSISTS THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL NECESSITATE THE INCLUSION OF 20-30 POPS FOR A LONG DURATION. THE TUESDAY INTO WEDNESDAY TIME FRAME IS TRENDING DRIER HOWEVER...AS DRY SURFACE HIGH PRESSURE BUILDS IN...SO MAY BE ABLE TO SHED SHOWER AND THUNDERSTORM CHANCES FOR THOSE DAYS. WEDNESDAY NIGHT INTO FRIDAY LOOK WET AGAIN HOWEVER....AS SHORTWAVE ENERGY CHANNELS THROUGH THE WESTERN PERIPHERY OF THE ONTARIO LOW. TEMPERATURES WILL REMAIN RELATIVELY STATIC THROUGH THE EXTENDED PERIOD...WITH HIGHS GENERALLY IN THE MID 70S TO LOWER 80S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 134 PM CDT FRI JUL 19 2013 NO PROBLEMS IN THE SHORT TERM. WE SHOULD LARGELY REMAIN DRY WITH VFR CONDITIONS TONIGHT AND MOST OF THE DAY TOMORROW. YOU WILL NOTICE A SMALL AREA OF THUNDERSTORMS NEAR THE ND/CANADIAN BORDER THIS AFTERNOON. IT IS POSSIBLE SOME OF THIS ACTIVITY WILL MAKE IT INTO WESTERN AND CENTRAL MN TONIGHT. INCLUDED A VCSH AT KAXN AND KRWF...BUT SHOWERS WILL BE WIDELY SCATTERED IF THEY OCCUR AT ALL. WE MAY END UP SEEING A FEW MORE MID CLOUDS LATE TONIGHT. KMSP... AS MENTIONED ABOVE...WE HAVE A GOOD CHANCE OF REMAINING DRY TONIGHT AND AT WORSE THE AIRPORT WILL SEE A LIGHT SHOWER OR A FEW SPRINKLES JUST BEFORE SUNRISE. VFR IS EXPECTED. /OUTLOOK FOR KMSP/ SAT NIGHT...MAINLY VFR. SLGT CHC -SHRA/-TSRA. NW WINDS 5-10 KTS. SUN...MAINLY VFR. CHC -SHRA/-TSRA. NE WINDS 5-10 KTS. MON...MAINLY VFR. CHC -SHRA/TSRA. SE-S WINDS 5 TO 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...DRL LONG TERM...LS AVIATION...CLF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
655 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 459 AM CDT FRI JUL 19 2013 OUR MPX WRF AND HOP WRF ARE ON SIMILAR PATHS WITH THE SHOWER AND THUNDERSTORM ACTIVITY EXITING OUR AREA BY 12Z. FOR TODAY...A BREAK FROM THE HEAT AND HUMIDITY WILL BE NOTED WITH SOME SCATTERED CLOUDS...EXCEPT FOR SOUTHWEST MN WHICH MAY BE CLOUD FREE. VERY DRY AIR ABOVE 6000 FEET WILL CONTINUE WORKING ITS ITS WAY INTO WESTERN MN. THERE IS SOME LOW LEVEL MOISTURE ACROSS EASTERN MN AND WESTERN WI. THE RAP KEEPS THIS MOISTURE IN PLACE UNTIL MID AFTERNOON. SHOULD BE PLENTY OF MIXING SO DO NOT EXPECT MORE THAN SCATTERED CLOUDS...EXCEPT SW MN WHERE IT MAY BE CLEAR. MAY BE CLEAR AFTER 21Z IN MOST AREAS AS DRIER AIR FILTERS IN. OVERNIGHT A SECONDARY COLD FRONT USHERS IN COOLER AIR AND BY SATURDAY MORNING A DISTURBANCE MOVES TOWARD WESTERN MN WITH AN INCREASE IN MOISTURE. NO PRECIPITATION EXPECTED THROUGH 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 459 AM CDT FRI JUL 19 2013 THE LONG TERM PORTION OF THE FORECAST WILL FEATURE RIDGING OVER THE ROCKIES...WITH EPISODIC IMPULSES PARADING ACROSS THE NORTHERN CONUS. THE FIRST OF THESE SHORTWAVES HAS BEEN CONSISTENTLY PROGGED TO ARRIVE ON SATURDAY NIGHT INTO SUNDAY BY DETERMINISTIC AND ENSEMBLE SOLUTIONS. FAIRLY IMPRESSIVE LIFT FROM 305-310K IS PROGGED TO BLOSSOM OVER THE AREA BETWEEN 06Z AND 12Z SUNDAY AS 925-850 MOISTURE TRANSPORT NOSES INTO SOUTHERN MN. HAVE INCLUDED 50-60 POPS FOR THIS TIME FRAME. NORTHWEST FLOW PERSISTS THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL NECESSITATE THE INCLUSION OF 20-30 POPS FOR A LONG DURATION. THE TUESDAY INTO WEDNESDAY TIME FRAME IS TRENDING DRIER HOWEVER...AS DRY SURFACE HIGH PRESSURE BUILDS IN...SO MAY BE ABLE TO SHED SHOWER AND THUNDERSTORM CHANCES FOR THOSE DAYS. WEDNESDAY NIGHT INTO FRIDAY LOOK WET AGAIN HOWEVER....AS SHORTWAVE ENERGY CHANNELS THROUGH THE WESTERN PERIPHERY OF THE ONTARIO LOW. TEMPERATURES WILL REMAIN RELATIVELY STATIC THROUGH THE EXTENDED PERIOD...WITH HIGHS GENERALLY IN THE MID 70S TO LOWER 80S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 643 AM CDT FRI JUL 19 2013 VFR ON TAP FOR THE DAY TODAY AT ALL TAF SITES. LOW LEVEL MOISTURE TO REMAIN IN PLACE MOST OF THE DAY OVER THE EASTERN AREAS. DRIER AIR MOVES INTO THE WESTERN AREAS TODAY WITH VERY DRY CONDITIONS ABOVE 6000 FEET. WITH GOOD MIXING WOULD NOT BE SURPRISED TO SEE SKC AT AXN/RWF. THE OTHER SITES SHOULD BE SCATTERED BECOMING SKC BY EVENING. WITH THE MIXING COMES FAIRLY GUSTY WINDS BY MID MORNING AND LASTING INTO THE EVENING HOURS. AS A DISTURBANCE APPROACHES THE STATE SATURDAY MORNING WE WILL SEE A RETURN TO SCATTERED TO BROKEN CLOUDS AND A CHANCE FOR PRECIPITATION ESPECIALLY IN THE WEST LATER SATURDAY. KMSP...VFR THROUGH THE PERIOD. BKN MID DECK SHOULD GIVE WAY TO SCT THEN FEW BY 00Z. GUSTY NORTHWEST WINDS TODAY. /OUTLOOK FOR KMSP/ SAT...MAINLY VFR. SLGT CHC -SHRA/-TSRA IN THE LATE AFTERNOON. NW WINDS 5-10 KTS. SUN...MAINLY VFR. CHC -SHRA/-TSRA. NE WINDS 5-10 KTS. MON...MAINLY VFR. CHC -SHRA/TSRA. SE-S WINDS 5 TO 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...DRL LONG TERM...LS AVIATION...DRL
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
459 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 459 AM CDT FRI JUL 19 2013 OUR MPX WRF AND HOP WRF ARE ON SIMILAR PATHS WITH THE SHOWER AND THUNDERSTORM ACTIVITY EXITING OUR AREA BY 12Z. FOR TODAY...A BREAK FROM THE HEAT AND HUMIDITY WILL BE NOTED WITH SOME SCATTERED CLOUDS...EXCEPT FOR SOUTHWEST MN WHICH MAY BE CLOUD FREE. VERY DRY AIR ABOVE 6000 FEET WILL CONTINUE WORKING ITS ITS WAY INTO WESTERN MN. THERE IS SOME LOW LEVEL MOISTURE ACROSS EASTERN MN AND WESTERN WI. THE RAP KEEPS THIS MOISTURE IN PLACE UNTIL MID AFTERNOON. SHOULD BE PLENTY OF MIXING SO DO NOT EXPECT MORE THAN SCATTERED CLOUDS...EXCEPT SW MN WHERE IT MAY BE CLEAR. MAY BE CLEAR AFTER 21Z IN MOST AREAS AS DRIER AIR FILTERS IN. OVERNIGHT A SECONDARY COLD FRONT USHERS IN COOLER AIR AND BY SATURDAY MORNING A DISTURBANCE MOVES TOWARD WESTERN MN WITH AN INCREASE IN MOISTURE. NO PRECIPITATION EXPECTED THROUGH 12Z SATURDAY. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 459 AM CDT FRI JUL 19 2013 THE LONG TERM PORTION OF THE FORECAST WILL FEATURE RIDGING OVER THE ROCKIES...WITH EPISODIC IMPULSES PARADING ACROSS THE NORTHERN CONUS. THE FIRST OF THESE SHORTWAVES HAS BEEN CONSISTENTLY PROGGED TO ARRIVE ON SATURDAY NIGHT INTO SUNDAY BY DETERMINISTIC AND ENSEMBLE SOLUTIONS. FAIRLY IMPRESSIVE LIFT FROM 305-310K IS PROGGED TO BLOSSOM OVER THE AREA BETWEEN 06Z AND 12Z SUNDAY AS 925-850 MOISTURE TRANSPORT NOSES INTO SOUTHERN MN. HAVE INCLUDED 50-60 POPS FOR THIS TIME FRAME. NORTHWEST FLOW PERSISTS THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL NECESSITATE THE INCLUSION OF 20-30 POPS FOR A LONG DURATION. THE TUESDAY INTO WEDNESDAY TIMEFRAME IS TRENDING DRIER HOWEVER...AS DRY SURFACE HIGH PRESSURE BUILDS IN...SO MAY BE ABLE TO SHED SHOWER AND THUNDERSTORM CHANCES FOR THOSE DAYS. WEDNESDAY NIGHT INTO FRIDAY LOOK WET AGAIN HOWEVER....AS SHORTWAVE ENERGY CHANNELS THROUGH THE WESTERN PERIPHERY OF THE ONTARIO LOW. TEMPERATURES WILL REMAIN RELATIVELY STATIC THROUGH THE EXTENDED PERIOD...WITH HIGHS GENERALY IN THE MID 70S TO LOWER 80S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1149 PM CDT THU JUL 18 2013 HAVE SCALED BACK PRECIP CHCS IN THE 06Z ISSUANCE AS MIDLVL RIDGING HAS PREVENTED MUCH IN THE WAY OF CONVECTIVE DEVELOPMENT FROM DROPPING S FROM NRN MN. THAT SAID...ISOLD ECHOES HAVE BEGUN TO SHOW UP IN W-CENTRAL MN ON THE KMPX RADAR. HOWEVER...LATEST SHORT- TERM MODEL RNUS INDICATE VERY LITTLE TO NEARLY NO CONVECTIVE ACTIVITY WILL IMPACT THE TERMINALS. LATEST POP UPDATE HAS DROPPED PRECIP CHCS TO NO HIGHER THAN 30 PERCENT SO HAVE OPTED TO RUN WITH A DRY FCST WITH CONFIDENCE QUITE LOW IN PREDICTING CONVECTION TO IMPACT ANY TERMINAL. CLOUD COVER WILL INCRS OVERNIGHT...LIKELY TO RESULT IN MIDLVL CIGS BUT STILL WELL UP IN VFR RANGE. SKIES WILL THEN STEADILY CLEAR OUT DURG THE DAY. MAINLY SW WINDS AT INITIALIZATION IN THE 6-10KT RANGE FROM GRADUALLY VEER TO THE W AND NW DURG THE DAY. SPEEDS WILL ALSO INCRS TO NEAR 15G25KT. KMSP...RAN WITH VFR THIS FCST PERIOD AS PRECIP CHCS HAVE BEEN REDUCED FOR THE FIRST 6 HRS OF THIS FCST. CLOUD COVER IS HARD TO FIND OVER CENTRAL MN AT INITIALIZATION BUT ADDITIONAL OBS HAVE STARTED TO REPORT SCT/BKN COVERAGE IN NRN AND W-CENTRAL MN. THESE WILL GRADUALLY GET INTO MSP DURG THE EARLY MRNG HRS...MAKING FOR A MIDLVL CIG. IF ANY PRECIP WERE TO OCCUR...BEST TIMING LOOKS TO BE 07Z-10Z...BUT WITH POPS LESS THAN 30 PERCENT...HAVE OPTED TO RUN WITH A DRY FCST. SKIES THEN GRADUALLY CLEAR OUT STARTING AROUND DAYBREAK THRU THE REST OF THE DAY. SW WINDS SETTLE DOWN TO THE 5-8 KT RANGE THEN VEER THROUGH DAYBREAK AS A CDFNT SLIPS S ACRS THE AREA. WINDS GRADUALLY BECOME NW BY LATE MRNG AND INCRS TO THE 15G25KT AREA BEFORE SETTLING DOWN FRI EVE. /OUTLOOK FOR KMSP/ SAT...MAINLY VFR. SLGT CHC -SHRA/-TSRA. NW WINDS 5-10 KTS. SUN...MAINLY VFR. CHC -SHRA/-TSRA. SE WINDS 5-10 KTS. MON...MAINLY VFR. CHC -SHRA/TSRA. S WINDS 5 TO 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...DRL LONG TERM...LS AVIATION...JPC
AREA FORECAST DISCUSSION
NWS DULUTH MN
1245 AM CDT FRI JUL 19 2013 .AVIATION.../00Z TAF ISSUANCE/ VFR CEILINGS WITH VCTS WILL BE COMMON THROUGH THE REMAINDER OF THE NIGHT AS A COLD FRONT MARCHES EAST ACROSS THE REGION. THE LINGERING SHOWERS AND STORMS WILL EXIT FRIDAY MORNING WITH INCREASING NORTHWEST WINDS THROUGH THE DAY. WIDESPREAD GUSTS AROUND 25 KT WILL BE FOUND BY FRIDAY AFTERNOON WITH MID LEVEL SCT/BKN CEILINGS. && PREV DISCUSSION... /ISSUED 304 PM CDT THU JUL 18 2013/ SHORT TERM.../THROUGH TONIGHT/ THE FOCUS IS ON THE THREAT OF SEVERE THUNDERSTORMS THROUGH THIS EVENING. THE STORM PREDICTION CENTER HAS POSTED ALL OF THE NORTHLAND IN AT LEAST A SLIGHT RISK OF SEVERE THUNDERSTORMS...AND A MODERATE RISK ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. LARGE HAIL AND HEAVY RAIN MAY BE THE INITIAL MAIN THREATS AND THEN QUICKLY TRANSITIONING TO A DAMAGING WIND THREAT. THE MODELS...ESPECIALLY THE HIGH RESOLUTION HRRR AND NCEP WRF SIMULATED REFLECTIVITY RUNS...HAVE BEEN INDICATING SUPERCELL THUNDERSTORMS WILL LIKELY DEVELOP IN NW AND NORTH CENTRAL MINNESOTA LATE THIS AFTERNOON OR EARLY THIS EVENING...AND THEN CONGEAL INTO A LINE OF STORMS THAT SWEEP THROUGH THE NORTHLAND THIS EVENING. A SEVERE THUNDERSTORM WATCH WILL LIKELY BE ISSUED WITHIN THE NEXT HOUR OR SO. THIS AFTERNOON AND EVENING...MUCH OF THE NORTHLAND HAS HOT AND MUGGY WEATHER WITH GUSTY SW WINDS AS A FRONT STRETCHES ACROSS WESTERN ONTARIO TO A LOW IN THE NORTHERN RED RIVER VALLEY. A STRONG COLD FRONT EXTENDS FROM SW FROM THE LOW THROUGH THE CENTRAL DAKOTAS. MOST OF THE NORTHLAND...SAVE FOR THE FAR NORTH AND OVER THE LAKE...HAS DEVELOPED AMPLE SURFACE BASED CAPE UP TO AROUND 3500 J/KG...MAXIMIZED ACROSS THE S AND SW FORECAST AREA. THERE IS LITTLE IF ANY INHIBITION. DEEP LAYER (0-6KM) WIND SHEAR OF 30 TO 50 KNOTS HAS DEVELOPED...WITH THE HIGHEST SHEAR ACROSS THE NORTHERN HALF OF THE FORECAST AREA. PRECIPITABLE WATER VALUES ARE AROUND 1.75 TO 2 INCHES. THERE SHOULD BE INCREASING CHANCES OF SHOWERS AND STORMS ACROSS THE FORECAST AREA THROUGH THE REST OF THE AFTERNOON...BUT THE FOCUS WILL BE ON THE WESTERN FORECAST AREA WHERE THE MODELS HAVE BEEN INDICATING THUNDERSTORMS...LIKELY AT FIRST SUPERCELLS...WILL DEVELOP IN NW AND NORTH CENTRAL MINNESOTA LATE THIS AFTERNOON NEAR THE LOW PRESSURE SYSTEM AND APPROACHING COLD FRONT. CONSIDERING THE AVAILABLE CAPE...CAPE SOUNDING PROFILES...AND DEEP LAYER WINDS...THE SUPERCELLS COULD EASILY DEVELOP LARGE HAIL...GUSTY WINDS...AND HEAVY RAIN. A STRAY TORNADO CANNOT BE RULED OUT. THE STORMS MAY QUICKLY CONGEAL...AS THE MODELS SUGGEST...INTO A LINE OF STORMS WITH A TRANSITIONING THREAT TO MAINLY DAMAGING WINDS AND HEAVY RAIN. THIS LINE AND COLD FRONT COULD SWEEP ESE THROUGH THE REST OF NE MINNESOTA AND THEN NW WISCONSIN PRETTY QUICKLY THIS EVENING. I ADDED WORDING TO THE FORECAST TO INCLUDE SEVERE THUNDERSTORMS AND THE LIKELY THREATS FOR WHEREVER MY PCPN CHANCES ARE LIKELY LATE THIS AFTERNOON THROUGH AROUND MIDNIGHT...WHICH IS BASICALLY MY BEST GUESS ON THE HOURLY TIMING OF THE MAIN LINE OF THUNDERSTORMS. LATE TONIGHT...THE SEVERE WEATHER THREAT SHOULD COME TO AN END AROUND MIDNIGHT AS THE MAIN LINE OF STORMS MOVES SE OF THE FORECAST AREA...BUT THERE COULD BE SOME LINGERING SHOWERS AND STORMS ACROSS THE SE FORECAST AREA NEAR THE FRONT. THERE SHOULD ALSO BE DECREASING CHANCES OF SHOWERS AND STORMS FROM NW TO SE...BUT I LEFT LOW CHANCES OF SHOWERS AND STORMS ACROSS MOST OF THE FORECAST AREA SINCE A SHORTWAVE WILL LIKELY MOVE INTO THE NORTHERN FORECAST AREA LATE TONIGHT. THIS SHORTWAVE COULD HELP DEVELOP SOME MORE SHOWERS AND STORMS. LONG TERM.../FRIDAY - WEDNESDAY/ THE WEST-NORTHWEST FLOW OF COOLER AND DRIER AIR WILL BE ESTABLISHED OVER THE FORECAST AREA BY FRIDAY MIDDAY. THERE WILL BE SOME LINGERING SHOWERS LEFT OVER FRIDAY MORNING BEFORE ENDING BY MIDDAY. THE WEST TO NORTHWEST FLOW WILL CONTINUE INTO SATURDAY BUT A WEAK SHORTWAVE WILL CAUSE A POSSIBILITY OF SHOWERS ACROSS THE REGION. THE RIDGE WILL MOVE EAST AND A RETURN FLOW OF MOISTURE TO THE FORECAST AREA ON SUNDAY. THIS WILL CONTINUE INTO MIDWEEK WITH WEAK SHORTWAVES PASSING THROUGH THE FLOW. THIS WILL KEEP A CHANCE FOR PRECIP ACROSS THE FORECAST AREA FOR THE TIME PERIOD. TEMPS WILL BE NEAR NORMAL THROUGH MOST OF THE WEEK. && .POINT TEMPS/POPS... DLH 52 70 49 69 / 10 10 20 20 INL 46 69 48 73 / 10 10 10 10 BRD 55 75 52 76 / 10 10 20 30 HYR 53 75 50 74 / 10 10 20 20 ASX 52 69 48 70 / 10 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR MNZ011-012- 019>021. WI...NONE. LS...NONE. && $$ AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS GLASGOW MT
904 PM MDT SAT JUL 20 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY... 9PM UPDATE...VERY ISOLATED THUNDERSTORMS CONTINUE IN THE SOUTHEASTERN CORNER AND NORTHWESTERN CORNER OF THE FORECAST AREA. DO EXPECT VERY ISOLATED THUNDERSTORM ACTIVITY TO CONTINUE THROUGH THE REST OF TONIGHT MAINLY FOR THE NORTHERN AND EASTERN AREAS. PROTON MADE ANOTHER UPDATE TO POPS AND WX GRIDS BASED ON THE LATEST MOVEMENT OF THE THUNDERSTORMS. THESE STORMS ARE PRODUCING BRIEF HEAVY RAIN...GUSTY WIND AND HAIL RANGING IN SIZE FROM DIME TO QUARTER. THEY ARE EXPECT TO DEPART THE AREA BY MID EVENING. SCT PREVIOUS UPDATE... MADE A QUICK UPDATE TO CHANGE AFTERNOON WX TO COVERAGE AND INCREASE POPS. A COUPLE OF STRONG STORMS HAVE POPPED UP WITH REPORTS OF HEAVY RAIN...SMALL HAIL...AND GUSTY WIND. SCT PREVIOUS DISCUSSION... CONVECTIVE ACTIVITY THIS AFTERNOON WILL CONTINUE TO DEVELOP OVER THE NEXT COUPLE OF HOURS BUT SHOULD DIMINISH PRETTY QUICK WITHOUT THE SHEAR IN PLACE. HRRR MODEL SHOWING JUST SCATTERED ACTIVITY AT BEST OVER THE NORTHEASTERN HALF OF THE CWA THIS EVENING. WITH AN UPPER TROUGH OVER THE EASTERN STATES AND A RIDGE TO OUR WEST...THE AREA IS UNDER A WEST-NORTHWEST FLOW. A DISTURBANCE...BOTH AT THE SURFACE AND ALOFT MOVES INTO SOUTHERN SASK LATER TONIGHT...KEEPING SHOWERS/THUNDERSTORMS GOING OVERNIGHT MAINLY TO THE NORTHEAST ZONES. SUNDAY...DISTURBANCE MOVES SOUTHEAST AND THROUGH THE CWA BRINGING AN INCREASE IN WEST WINDS DURING THE AFTERNOON. THEY SHOULD BE STRONG ENOUGH TO CAUSE PROBLEMS FOR FORT PECK LAKE FROM NOON UNTIL 9 PM...SO ISSUED A LAKE WIND ADVISORY. ON MONDAY...BACKDOOR FRONT THAT LIES NW TO SE ACROSS MONTANA SUNDAY NIGHT HELPS TO FIRE UP THUNDERSTORMS AS A VORT MAX MOVES IN FROM THE WEST. ACTIVITY MOVES IN FROM THE WEST WITH MORE ACTIVITY EXPECTED DURING THE EVENING. TFJ .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... AN UPPER LEVEL RIDGE IN THE WEST AND A PERSISTENT UPPER TROUGH CENTERED OVER NORTHERN QUEBEC WILL MAINTAIN A NORTHWEST FLOW OVER NORTHEAST MONTANA THROUGH MOST OF THE PERIOD. WEAK EMBEDDED DISTURBANCES IN THE UPPER FLOW WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS TO THE REGION THROUGHOUT THE PERIOD. MONDAY EVENING AND OVERNIGHT GFS SENDS A DISTURBANCE FLOWING ALONG THE STATIONARY BOUNDARY THAT WILL INITIATE THUNDERSTORMS ACROSS NEMONT. WITH SOME AGREEMENT FROM THE 00Z EC...WENT AHEAD AND ADJUSTED POPS TO CHANCE. TUESDAY THROUGH SATURDAY THE FLUCTUATING STATIONARY BOUNDARY AND WEAK DISTURBANCES WILL GENERATE A FEW STORMS EACH DAY. THIS IS REFLECTED IN THE INHERITED GRIDS AND NO CHANGES ARE PLANNED HERE. SCT SYNOPTIC SET UP... A LARGE HIGH PRESSURE HEAT DOME IS CENTERED OVER THE LOWER INTER-MOUNTAIN WEST. A RIDGE SPUR RUNS NORTH OF THIS DOME INTO BRITISH COLUMBIA. A LARGE TROUGH EXTENDS FROM THE NORTHERN US PLAINS INTO MANITOBA AND UP THROUGH NUNAVUT. NORTHEAST MONTANA LIES BETWEEN THESE TWO FEATURES IN A ZONAL TO NORTHWEST FLOW PATTERN. ANOTHER LARGE TROUGH LIES OFF THE COAST OF BRITISH COLUMBIA. MONDAY NIGHT THROUGH THURSDAY NIGHT... NORTHWEST FLOW WILL END UP ALLOWING HIGH POP CHANCE ACROSS THE NORTHEAST DRYING TOWARD THE SOUTHWEST. THIS GRADIENT WILL BEGIN A BIT MORE SHARP MONDAY NIGHT BUT WILL SLOWLY DIFFUSE OUT TOWARD THURSDAY NIGHT AS JETS AND SHORTWAVES BECOME MORE FUZZY IN TIME. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS DO EXIST ALMOST EVERY PERIOD. FRIDAY ONWARD... THE PATTERN WILL BECOME A LITTLE MORE PROGRESSIVE AS THE RIDGE TO THE WEST SETTLES OVER THE MONTANA HIGH PLAINS. THIS SHOULD EDGE TEMPERATURES UP BUT POPS WILL PROBABLY REMAIN AS THE ATMOSPHERE BECOMES MORE DESTABILIZED. HOWEVER... QPF IS EXPECTED TO LOWER AS PLANTS BEGIN TO STRESS FROM PROGRESSIVELY DRIER HOTTER DAYS AND SOILS FOLLOWED BY THE SURFACE LAYER OF THE ATMOSPHERE DRY OUT. GAH && .AVIATION... GENERALLY VFR. HOWEVER A WEAK UPPER LEVEL DISTURBANCE FLOWING OVER A STATIONARY SURFACE BOUNDARY WILL INITIATE ISOLATED TO SCATTERED AFTERNOON/EVENING THUNDERSTORMS THAT COULD AFFECT ANY OF THE TAF SITES. SCT && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM NOON TO 9 PM MDT SUNDAY FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
819 PM MDT SAT JUL 20 2013 .UPDATE... KEEPING A CLOSE EYE ON A SEVERE THUNDERSTORM MOVING QUICKLY SE THROUGH DAWSON COUNTY TO THE NE OF THE FORECAST AREA. HAVE INCREASED POPS IN PATH OF THIS STORM OVER FALLON...NE CUSTER COUNTY AND NORTHERN CARTER COUNTY THROUGH THE EVENING. MESO ANALYSIS INDICATED 50 KT OF SHEAR OVER THE EASTERN PART OF THE FORECAST AREA AND RAP KBHK SOUNDING HAD CAPES CLOSE TO 1000 J/KG. JET ENERGY AND SHORTWAVES IN THE AREA WERE FUELING LIFT FOR THE STORM. STORM WAS ALSO RIDING ALONG AN OUTFLOW BOUNDARY FROM PREVIOUS STORMS OVER NE MT. OTHER FORECAST PARAMETERS WERE ON TRACK. ARTHUR && .SHORT TERM...VALID FOR SUN AND MON... ISOLATED CONVECTION HAS DEVELOPED OVER THE SNOWIES THIS AFTERNOON. ACTIVITY NOT MAKING IT VERY FAR OFF THE MOUNTAINS...SO THOUGH ADDED LOW POPS TO AREAS NORTH...DID NOT GO TOO FAR EAST WITH THEM THE REST OF THE AFTERNOON AND EVENING. SUNDAY LOOKS TO BE VERY WARM AND DRY. 700MB TEMPERATURES APPROACH 13C WITH PRECIPITABLE WATER VALUES BELOW A HALF INCH FOR THE WESTERN HALF OF THE AREA. A MID LEVEL FRONT IS PROGGED TO SLIDE THROUGH DURING THE AFTERNOON AND THIS WILL HELP TO MIX THE ATMOSPHERE DEEPLY. THIS WILL CAUSE DEWPOINTS TO CRASH IN THE AFTERNOON WITH HUMIDITIES FALLING WELL INTO THE TEENS. SHORTWAVE ACTIVITY WILL BE QUITE MINIMAL...SO NOT EXPECTING CONVECTION. A SHORTWAVE TROUGH MOVES INTO NORTH CENTRAL MONTANA SUNDAY AFTERNOON. DEWPOINTS WILL REMAIN LOW AND WILL THUS KEEP THE CENTRAL AND WESTERN ZONES DRY. WILL BRUSH LOW POPS INTO THE EASTERN ZONES AS A SURFACE LOW MOVES IN THERE FOR SOME LOW LEVEL CONVERGENCE. LOW LEVEL WINDS WILL TURN EAST THERE TOO AND PROVIDE ACCESS TO SLIGHTLY HIGHER DEWPOINTS. STORMS WILL HAVE GUSTY WINDS WITH INVERTED V SOUNDINGS AND ELEVATED CAPE. MONDAY WILL STILL BE WARM WITH THE MID LEVEL FRONT BEING COUNTERACTED BY MIXING. TWH .LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT... MODELS CONTINUE TO BE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED. CURRENT FORECAST LOOKS TO BE IN GOOD SHAPE SO DID NOT MAKE ANY SIGNIFICANT CHANGES WITH THIS ISSUANCE. RIDGING BEGINS TO BUILD ACROSS THE FORECAST AREA TUESDAY AND WEDNESDAY AND BECOMES A BIT STRONGER BY THE END OF THE WEEK INTO NEXT WEEKEND. A FEW UPPER LEVEL DISTURBANCES MAY MOVE NORTHEAST OUT OF THE GREAT BASIN AREA AND POSSIBLY UNDERCUT THE RIDGE WEDNESDAY INTO THURSDAY. HOWEVER...THE LATEST MODELS SHOW THE BULK OF THESE DISTURBANCES MAY MOVE TO THE NORTH AND SOUTH OF OUR AREA WITH THE NORTHERN PORTION MOVING ALONG THE RIDGE PERIPHERY ACROSS NORTHERN AND THEN EASTERN MONTANA. AS A RESULT...BEST THUNDERSTORM CHANCES LOOK TO BE ALONG THE MONTANA/WYOMING BORDER AND ACROSS EASTERN MONTANA. AFTERNOON TEMPERATURES CONTINUE TO LOOK A FEW DEGREES ABOVE AND BELOW NORMAL WITH READINGS IN THE MIDDLE 80S TO LOWER 90S. HOOLEY && .AVIATION... VFR WILL PREVAIL OVER THE AREA TONIGHT AND SAT. HOWEVER...AREAS E AND SE OF KMLS WILL HAVE IFR TO VLIFR CONDITIONS THROUGH 06Z DUE TO A STRONG TO SEVERE THUNDERSTORM MOVING INTO THE AREA. LARGE HAIL...WIND GUSTS TO 60 KT AND VERY HEAVY RAINFALL WILL BE POSSIBLE WITH THIS STORM. ARTHUR && .PRELIMINARY POINT TEMP/POPS... SUN MON TUE WED THU FRI SAT ----------------------------------------------------------- BIL 060/093 061/092 061/090 061/091 062/086 060/087 061/088 10/U 01/U 00/U 11/U 12/T 22/T 12/T LVM 046/092 047/092 049/090 052/091 054/085 052/087 053/088 00/U 00/U 00/U 01/U 12/T 22/T 11/B HDN 059/094 059/094 059/089 060/091 061/087 058/087 060/090 10/U 01/U 00/U 11/U 22/T 22/T 12/T MLS 062/094 062/092 063/089 062/090 064/087 062/087 063/090 10/N 02/T 21/U 11/U 22/T 22/T 12/T 4BQ 059/093 058/093 058/088 058/092 060/086 057/084 057/088 10/U 01/U 21/U 11/U 22/T 22/T 22/T BHK 057/090 057/085 058/082 057/084 058/086 058/081 057/083 50/U 02/T 22/T 21/U 22/T 22/T 12/T SHR 055/094 053/093 056/088 057/093 056/087 056/086 056/088 10/U 01/U 00/U 01/U 22/T 22/T 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
654 PM MDT SAT JUL 20 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY... MADE ANOTHER UPDATE TO POPS AND WX GRIDS BASED ON THE LATEST MOVEMENT OF THE THUNDERSTORMS. THESE STORMS ARE PRODUCING BRIEF HEAVY RAIN...GUSTY WIND AND HAIL RANGING IN SIZE FROM DIME TO QUARTER. THEY ARE EXPECT TO DEPART THE AREA BY MID EVENING. SCT PREVIOUS UPDATE... MADE A QUICK UPDATE TO CHANGE AFTERNOON WX TO COVERAGE AND INCREASE POPS. A COUPLE OF STRONG STORMS HAVE POPPED UP WITH REPORTS OF HEAVY RAIN...SMALL HAIL...AND GUSTY WIND. SCT PREVIOUS DISCUSSION... CONVECTIVE ACTIVITY THIS AFTERNOON WILL CONTINUE TO DEVELOP OVER THE NEXT COUPLE OF HOURS BUT SHOULD DIMINISH PRETTY QUICK WITHOUT THE SHEAR IN PLACE. HRRR MODEL SHOWING JUST SCATTERED ACTIVITY AT BEST OVER THE NORTHEASTERN HALF OF THE CWA THIS EVENING. WITH AN UPPER TROUGH OVER THE EASTERN STATES AND A RIDGE TO OUR WEST...THE AREA IS UNDER A WEST-NORTHWEST FLOW. A DISTURBANCE...BOTH AT THE SURFACE AND ALOFT MOVES INTO SOUTHERN SASK LATER TONIGHT...KEEPING SHOWERS/THUNDERSTORMS GOING OVERNIGHT MAINLY TO THE NORTHEAST ZONES. SUNDAY...DISTURBANCE MOVES SOUTHEAST AND THROUGH THE CWA BRINGING AN INCREASE IN WEST WINDS DURING THE AFTERNOON. THEY SHOULD BE STRONG ENOUGH TO CAUSE PROBLEMS FOR FORT PECK LAKE FROM NOON UNTIL 9 PM...SO ISSUED A LAKE WIND ADVISORY. ON MONDAY...BACKDOOR FRONT THAT LIES NW TO SE ACROSS MONTANA SUNDAY NIGHT HELPS TO FIRE UP THUNDERSTORMS AS A VORT MAX MOVES IN FROM THE WEST. ACTIVITY MOVES IN FROM THE WEST WITH MORE ACTIVITY EXPECTED DURING THE EVENING. TFJ .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... AN UPPER LEVEL RIDGE IN THE WEST AND A PERSISTENT UPPER TROUGH CENTERED OVER NORTHERN QUEBEC WILL MAINTAIN A NORTHWEST FLOW OVER NORTHEAST MONTANA THROUGH MOST OF THE PERIOD. WEAK EMBEDDED DISTURBANCES IN THE UPPER FLOW WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS TO THE REGION THROUGHOUT THE PERIOD. MONDAY EVENING AND OVERNIGHT GFS SENDS A DISTURBANCE FLOWING ALONG THE STATIONARY BOUNDARY THAT WILL INITIATE THUNDERSTORMS ACROSS NEMONT. WITH SOME AGREEMENT FROM THE 00Z EC...WENT AHEAD AND ADJUSTED POPS TO CHANCE. TUESDAY THROUGH SATURDAY THE FLUCTUATING STATIONARY BOUNDARY AND WEAK DISTURBANCES WILL GENERATE A FEW STORMS EACH DAY. THIS IS REFLECTED IN THE INHERITED GRIDS AND NO CHANGES ARE PLANNED HERE. SCT SYNOPTIC SET UP... A LARGE HIGH PRESSURE HEAT DOME IS CENTERED OVER THE LOWER INTER-MOUNTAIN WEST. A RIDGE SPUR RUNS NORTH OF THIS DOME INTO BRITISH COLUMBIA. A LARGE TROUGH EXTENDS FROM THE NORTHERN US PLAINS INTO MANITOBA AND UP THROUGH NUNAVUT. NORTHEAST MONTANA LIES BETWEEN THESE TWO FEATURES IN A ZONAL TO NORTHWEST FLOW PATTERN. ANOTHER LARGE TROUGH LIES OFF THE COAST OF BRITISH COLUMBIA. MONDAY NIGHT THROUGH THURSDAY NIGHT... NORTHWEST FLOW WILL END UP ALLOWING HIGH POP CHANCE ACROSS THE NORTHEAST DRYING TOWARD THE SOUTHWEST. THIS GRADIENT WILL BEGIN A BIT MORE SHARP MONDAY NIGHT BUT WILL SLOWLY DIFFUSE OUT TOWARD THURSDAY NIGHT AS JETS AND SHORTWAVES BECOME MORE FUZZY IN TIME. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS DO EXIST ALMOST EVERY PERIOD. FRIDAY ONWARD... THE PATTERN WILL BECOME A LITTLE MORE PROGRESSIVE AS THE RIDGE TO THE WEST SETTLES OVER THE MONTANA HIGH PLAINS. THIS SHOULD EDGE TEMPERATURES UP BUT POPS WILL PROBABLY REMAIN AS THE ATMOSPHERE BECOMES MORE DESTABILIZED. HOWEVER... QPF IS EXPECTED TO LOWER AS PLANTS BEGIN TO STRESS FROM PROGRESSIVELY DRIER HOTTER DAYS AND SOILS FOLLOWED BY THE SURFACE LAYER OF THE ATMOSPHERE DRY OUT. GAH && .AVIATION... GENERALLY VFR. HOWEVER A WEAK UPPER LEVEL DISTURBANCE FLOWING OVER A STATIONARY SURFACE BOUNDARY WILL INITIATE ISOLATED TO SCATTERED AFTERNOON/EVENING THUNDERSTORMS THAT COULD AFFECT ANY OF THE TAF SITES. SCT && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM NOON TO 9 PM MDT SUNDAY FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
944 PM CDT SAT JUL 20 2013 .UPDATE... ISSUED AT 942 PM CDT SAT JUL 20 2013 AS WAS THE CASE DURING THE PRECEDING DAY SHIFT...CONFIDENCE IN THUNDERSTORM TRENDS/RAIN CHANCES THROUGH THE OVERNIGHT HOURS CONTINUES TO RUN AT LESS-THAN-IDEAL LEVELS. FOR AT LEAST A SHORT TIME LONGER...THE ENTIRE CWA CONTINUES IN A MULTI-HOUR LULL IN THE WAKE OF AFTERNOON CONVECTION THAT HAS SINCE EXITED WELL SOUTHEAST OF THE CWA. ALTHOUGH AREAS FROM THE TRI-CITIES AND WEST/NORTHWEST ESSENTIALLY MISSED OUT ON THE EARLIER ROUND...SEVERAL SMALL POCKETS ACROSS NORTH CENTRAL KS AND FAR SOUTHERN NEB RECEIVED A QUICK 1-4 INCH DRENCHING PER OUR LOCAL STORM REPORTS. LOOKING AHEAD...THE ONLY SHOW IN TOWN AT THE 9 PM HOUR IS A SMALL LINEAR COMPLEX OF STRONG TO MARGINALLY SEVERE STORMS TRACKING SOUTH- SOUTHEAST THROUGH THE WEST CENTRAL/NORTH CENTRAL NEB SANDHILLS...BUT GRADUALLY APPROACHING THE FRINGES OF THE CWA. FARTHER UPSTREAM...ADDITIONAL CLUSTERS OF STRONG-SEVERE STORMS HAVE TAKEN OFF IN SOUTHERN SD. ON THE LARGE SCALE ALOFT...SEASONABLY DECENT WEST-NORTHWEST FLOW WILL PERSIST THROUGH THE NIGHT MAINLY AT/ABOVE 500 MILLIBARS...WHILE FAIRLY CHAOTIC AND LIGHT FLOW PERSISTS A BIT LOWER AT 700MB...AND LOWER YET EVEN THE FLOW AT 850MB APPEARS QUITE UNDERWHELMING...WITH THE PRIMARY EXIT REGION OF A FAIRLY WEAK LOW LEVEL JET AIMED NORTH OF THE LOCAL AREA NEAR THE NEB/SD BORDER. AS A RESULT...GIVEN THE LACK OF NOTABLE THETA-E ADVECTION/CONVERGENCE IN AND NEAR THE CWA AT BOTH THE 850/700MB LEVEL...OUR CURRENTLY-ADVERTISED 50+ PERCENT POPS ACROSS THE MAJORITY OF THE CWA OVERNIGHT ARE COMING INCREASINGLY UNDER QUESTION ESPECIALLY IN THE CENTRAL/SOUTHEAST COUNTIES. NOT SURPRISINGLY...THE LATEST 00Z NAM AND HRRR ARE BOTH PRETTY PALTRY WITH MEASURABLE RAIN POTENTIAL OVERNIGHT. BASED ON CURRENT RADAR TRENDS...IT MAY VERY WELL END UP BEING THE CASE THAT THE BEST HOPE FOR LEGITIMATE RAINFALL WILL HINGE ON HOW SUCCESSFULLY THE ACTIVITY CURRENTLY DRIFTING TOWARD THE FAR NORTHWEST EDGES OF THE CWA HOLDS TOGETHER OVER THE NEXT FEW HOURS. PER THE LATEST RAP INSTABILITY TRENDS...THERE COULD BE AT LEAST A MODEST INCREASE IN ELEVATED MUCAPE IN THE 850-700MB LAYER INTO THE 500-1000 J/KG RANGE AS THE NIGHT WEARS ON...BUT MODEL SOUNDINGS SHOW THAT EVEN MUCH OF THIS INSTABILITY MAY BE RATHER CAPPED. AS FOR ANY OVERNIGHT SEVERE THREAT...THAT ALSO APPEARS TO BE ON A DECLINE...UNLESS SOMEHOW THE CONVECTION CURRENTLY IN THE NORTH PLATTE CWA RE-INTENSIFIES OR DEVELOPS A NEW VIGOROUS COLD POOL OVER THE NEXT FEW HOURS. HAIL-WISE...IT MAY BE TOUGH TO GET ANYTHING LARGER THAN DIMES-NICKELS GIVEN LATEST INSTABILITY TRENDS. IN SUMMARY...WILL CONTINUE TO EXAMINE THE LATEST TRENDS AND POTENTIALLY DECREASE POPS ACROSS PARTS OF THE CWA IN A FORTHCOMING EVENING UPDATE...BUT IN THE CONTINUED PRESENCE OF SUBTLE NORTHWEST-FLOW FORCING...PROBABLY CANNOT EXCLUDE ANY LOCATION FROM AT LEAST A TOKEN 20 PERCENT CHANCE OF SHOWERS/STORMS OVERNIGHT...AS NORTHWEST FLOW IS NOTORIOUS FOR PROVIDING A FEW SURPRISES. BY AND LARGE THOUGH...ITS STARTING TO LOOK LIKE THE 50+ POPS WE/VE BEEN ADVERTISING THE PAST FEW DAYS MAY PROVE OVERDONE FOR A DECENT CHUNK OF THE AREA...ESPECIALLY FOR THOSE LOOKING FOR MORE THAN A FEW TENTHS OF AN INCH. ALSO MAY BE MAKING A FEW DOWNWARD TWEAKS TO OVERNIGHT LOW TEMPS BASED ON LATEST OBSERVATIONAL TRENDS AND GUIDANCE. WILL BE DEFER TO ONCOMING OVERNIGHT SHIFT TO MAKE CHANGES BEYOND 12Z SUNDAY MORNING...BUT IT APPEARS IT COULD BE ANOTHER DAY/NIGHT OF FICKLE THUNDERSTORM TRENDS. LOOK FOR NEXT ROUND OF FORECAST UPDATES TO BE OUT BETWEEN 10-1030 PM... && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 353 PM CDT SAT JUL 20 2013 ALOFT: QUASI-ZONAL WNW FLOW WILL CONT THRU 00Z/MON. WV IMAGERY SHOWS A SUBTLE SHRTWV TROF MOVING INTO THE PANHANDLE FROM WY. THIS TROF IS FCST TO DEEPEN TNGT...CROSS THE FCST AREA SUN MRNG...AND WILL BE MOVING INTO NERN KS DURING PEAK HEATING. WHILE THIS TROF MAY AID TSTM DEVELOPMENT TNGT...HAVE TO WONDER IF SUBSIDENCE IN ITS WAKE WILL CAP OFF TSTM THREAT SUN AFTN. SFC: NUMEROUS OUTFLOW BOUNDARIES WILL LINGER THRU SUN. THE LEE/HEAT LOW WILL STRENGTHEN AND DRIFT INTO WRN KS. THIS SHOULD DROP DWPTS SUBSTANTIALLY FROM MCK-PHG-RCP AND PROBABLY DID NOT GO LOW ENOUGH. RAINFALL: PLEASE FOLLOW OUR LOCAL STORM REPORTS /LSR/. WE HAVE SEEN SOME SUBSTANTIAL 2-3 INCH AMTS BUT IT HAS BEEN FEAST OR FAMINE. REST OF THIS AFTN: THE ATMS HAS APPARENTLY STABILIZED OVER MUCH OF S-CNTRL NEB BASED ON THE LACK OF CU AND A WWD MOVING OUTFLOW BOUNDARY W OF HWY 283. SCT TSTMS WILL GRADUALLY DIE OFF OVER N-CNTRL KS. TNGT: PROBABLY SOMEWHAT OF A BREAK THIS EVNG. WE WERE WATCHING UPSTREAM TSTMS OVER THE PANHANDLE...WHICH THE MODELS SUGGESTED WOULD PROPAGATE INTO S-CNTRL NEB. THOSE TSTMS HAVE DIED WHICH LOWERS CONFIDENCE IN TNGT/S FCST...ESPECIALLY SINCE VIS SATPIX SHOW NO AGITATED CU FIELDS. SOME SEMBLANCE OF A COUPLED ULJ DEVELOPS TNGT...WHICH WILL ENHANCE THE LLJ. SO THE ENVIRONMENT WILL REMAIN FAVORABLE FOR ADDITIONAL TSTM DEVELOPMENT. SUN: IT ALL HINGES ON WHAT HAPPENS TNGT. IF SCT TSTMS FORM AND MOVE THRU THEN WE/LL SEE TSTMS DEPARTING DURING THE MRNG HRS WITH CLEARING THEREAFTER. FCST SOUNDINGS INDICATE DAYTIME HEATING SHOULD ERODE THE CAP. LEFTOVER OUTFLOW BOUNDARIES WILL PROVIDE FOCI FOR TSTM DEVELOPMENT. HOWEVER...IT APPEARS DOUBTFUL WE SEE ANYTHING MORE THAN AN ISOLATED TSTM MAYBE TWO? LARGE-SCALE SUBSIDENCE COULD LIMIT OR MITIGATE THE THREAT ALTOGETHER. IT/S POSSIBLE MODEL SOUNDINGS ARE NOT FULLY DEPICTING THIS. QPF IS PRETTY MEAGER SO IT MAY BE OF LITTLE CONSEQUENCE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 353 PM CDT SAT JUL 20 2013 GUIDANCE SUGGESTS NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER THE CENTRAL PLAINS THROUGH MUCH OF THE EXTENDED FORECAST PERIOD. THERE WILL BE THE POTENTIAL FOR MULTIPLE SMALL SCALE PERTURBATIONS TO WORK THEIR WAY ACROSS THE REGION AS A RESULT...WITH QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN SUGGESTING PRECIPITATION WILL BE REALIZED OVER VARIOUS PORTIONS OF OUR AREA DURING THE EXTENDED FORECAST PERIOD. AN EVEN AVERAGE OF THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN WAS UTILIZED TO DERIVE QPF FIELDS AND RESULTANT POPS FOR MONDAY AND TUESDAY...WHICH RESULTS IN LOW POPS BEING PRESENTED TO MOST ALL OF THE CWA BOTH DAYS. THE SAME PATTERN IS EXPECTED TO PERSIST THROUGH MUCH OF THE REST OF THE WEEK AS WELL...WITH ALLBLEND PROVIDING 20-60% POPS TO THE CWA AS A RESULT. THESE POPS WERE LEFT UNCHANGED FOR THE MOST PART. AS FOR SEVERE WEATHER CHANCES DURING THE EXTENDED FORECAST PERIOD...PERSISTENT LOW LEVEL MOISTURE SHOULD PRESENT DECENT CAPE VALUES ACROSS THE AREA...WITH GUIDANCE SUGGESTING SUCH VALUES WILL AVERAGE FROM 1500 TO 3000J/KG ON MOST DAYS. GIVEN THE UNCERTAINTY OF PLACEMENT AND TIMING OF SEVERE WEATHER HOWEVER...WILL PROVIDE A VAGUE SEVERE WEATHER MENTION IN THE HWO FOR MONDAY BUT LEAVE OUT ANY MENTION OF SEVERE WEATHER THROUGH THE REMAINDER OF THE EXTENDED FORECAST PERIOD. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT AFTERNOON HIGH TEMPERATURES IN THE 90S TO START THE EXTENDED FORECAST PERIOD...WITH SLIGHTLY COOLER AIR PROVIDING AFTERNOON HIGHS IN THE 80S TO NEAR 90 BY THE END OF THE EXTENDED FORECAST PERIOD. OVERNIGHT LOW TEMPERATURES IN THE 60S ARE EXPECTED FOR MOST PART DURING THE EXTENDED FORECAST PERIOD. && .AVIATION...(FOR THE 00Z KGRI TAF THROUGH 00Z SUNDAY EVENING) ISSUED AT 653 PM CDT SAT JUL 20 2013 AT LEAST FOR THE TIME BEING...WILL MAINTAIN VFR CEILING/VISIBILITY AND FAIRLY LIGHT BREEZES THROUGHOUT THE NEXT 24 HOURS...BUT PLEASE NOTE THIS DOES NOT TAKE INTO ACCOUNT THE STILL-TOO-SOON-TO-RESOLVE EFFECTS THAT THUNDERSTORMS COULD HAVE ON THE TERMINAL. AS FOR THESE STORM CHANCES...WILL CONTINUE TO CARRY A VICINITY THUNDERSTORM MENTION DURING A 7-HOUR BLOCK FROM 04Z-11Z TONIGHT...AS THIS APPEARED TO BE THE MOST FAVORED WINDOW OF OPPORTUNITY. SHOULD STORMS MOVING GENERALLY TOWARD THE AREA FROM NORTHWEST NEBRASKA MAINTAIN A CONSISTENT TRACK OVER THE NEXT SEVERAL HOURS...ITS QUITE POSSIBLE THAT A MORE-REFINED TEMPO GROUP MAY BE INTRODUCED LATER THIS EVENING. SHOULD STORMS MOVE IN LATER...AT LEAST A BRIEF PERIOD OF HEAVY RAIN AND GUSTS IN EXCESS OF 30-40KT CANNOT BE RULED OUT. BEYOND 11Z SUNDAY MORNING...WILL KEEP THE FORECAST VOID OF THUNDERSTORM MENTION...BUT ITS NOT OUT OF THE QUESTION THAT ADDITIONAL STORM CHANCES COULD CREEP BACK INTO THE PICTURE MAINLY LATE SUNDAY AFTERNOON...BUT CONFIDENCE IS FAR TOO LOW TO INTRODUCE THIS INTO THE FORECAST YET. SHOULD RAIN HAPPEN TO FALL AT KGRI LATER TONIGHT...THE COMBINATION OF WET GROUND AND GENERALLY LIGHT/VARIABLE BREEZES COULD RESULT IN AT LEAST LIGHT FOG/MVFR VISIBILITY RESTRICTIONS...BUT AGAIN WITH SO MUCH UNCERTAINTY IN STORM TIMING IN THE FIRST PLACE...WILL ACKNOWLEDGE FOG AS A LOW PROBABILITY CAVEAT FOR NOW...AND NOT INSERT INTO THE TAF. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...PFANNKUCH SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
637 PM CDT SAT JUL 20 2013 .SYNOPSIS... ISSUED AT 253 PM CDT SAT JUL 20 2013 THE H5 ANALYSIS THIS MORNING...HAS AN ACTIVE NW FLOW PATTERN ACROSS THE NRN CONUS. HIGH PRESSURE WAS ANCHORED ACROSS THE CENTRAL VALLEY OF CA...WITH A PERSISTENT BERMUDA HIGH PRESENT ACROSS THE WESTERN ATLANTIC. A BROAD TROUGH OF LOW PRESSURE EXTENDED FROM NRN QUEBEC INTO THE MID ATLANTIC STATES. ACROSS THE NRN ROCKIES AND CENTRAL PLAINS...NUMEROUS SHORTWAVES WERE EMBEDDED IN THE NWRLY FLOW. ONE OVER NWRN WYOMING...AND A SECOND OVER THE IDAHO PANHANDLE. ANOTHER DISTURBANCE WAS NOTED OVER NWRN IA AS WELL. AT THE SURFACE...SHOWERS AND THUNDERSTORMS HAVE CONTINUED ACROSS NORTHERN NEBRASKA THIS MORNING AND EARLY THIS AFTERNOON...ALONG A WEAK SURFACE BOUNDARY. TEMPERATURES AS OF 2 PM CDT RANGED FROM 68 IN RAIN COOLED AIR AT ONEILL...TO 87 AT OGALLALA...IMPERIAL AND NORTH PLATTE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 SCATTERED THUNDERSTORMS THIS AFTERNOON ARE EXPECTED TO DEVELOP OVER THE NEBRASKA PANHANDLE AND NORTHWEST NEBRASKA AND COALESCE INTO A CONVECTIVE SYSTEM BY EARLY THIS EVENING. WITH THE DEEP SHEAR VECTORS DIAGONAL TO THE LOW LEVEL BOUNDARY...IT APPEARS TO FAVOR THE DEVELOPMENT OF A LINEAR CONVECTIVE SYSTEM. ACCORDING TO THE SHORT RANGE HRRR AND RAP13...THE SYSTEM WILL AFFECT A LARGE PART OF THE SANDHILLS AND SOUTHWEST NEBRASKA BY 01Z AND FINALLY CLEARING CENTRAL NEBRASKA BY 09Z. THEY DO INDICATE SOME LINGERING SHOWERS AND THUNDERSTORMS EVEN INTO EARLY SUNDAY. INSTABILITY CONTINUES OVER WESTERN NEBRASKA SUNDAY AND THERE IS A CHANCE OF ANOTHER CONVECTIVE SYSTEM DEVELOPING IN SOUTH DAKOTA AND NORTHWEST NEBRASKA LATE SUNDAY MORNING OR EARLY AFTERNOON...THEN CROSSING WESTERN NEBRASKA THROUGH THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 MID RANGE...SUNDAY NIGHT THROUGH TUESDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO TUESDAY...THANKS TO NWLY FLOW AND THE PRESENCE OF EMBEDDED SHORTWAVES WITHIN THAT FLOW. BEGINNING SUNDAY NIGHT...ANOTHER UPPER LEVEL DISTURBANCE WILL TRACK FROM THE CENTRAL AND NORTHERN ROCKIES...ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. CONVECTION WILL BE ONGOING BY SUNDAY AFTERNOON AND IS EXPECTED TO IMPACT MOST OF THE FORECAST AREA DURING THE EVENING AND OVERNIGHT HOURS. ATTM...WILL PAINT THE HIGHEST POPS IN THE CENTRAL AND SOUTHWESTERN CWA...AS THESE LOCATIONS WILL SEE THE BEST DEEP LAYER SHEAR OF 30 TO 40 KTS. SHEAR IN THE NERN ZONES WILL RUN 10 TO 20 KTS SUNDAY EVENING...SO ANY TSRAS IN THESE AREAS WILL BE FEW AND FAR BETWEEN. WILL CONTINUE MENTION OF THUNDERSTORMS IN THE FORECAST OVERNIGHT IN THE SOUTHWESTERN ZONES AS THERE ARE INDICATIONS OF THE DEVELOPMENT OF A LOW LEVEL JET...WHICH BECOMES FOCUSED ACROSS SWRN AND CENTRAL NEBRASKA OVERNIGHT SUNDAY NIGHT. CONVECTION ALONG WITH THE EXITING DISTURBANCE...WILL FORCE A FRONTAL BOUNDARY THROUGH THE FORECAST AREA ON MONDAY...STALLING THIS FEATURE ACROSS CENTRAL AND EASTERN NEBRASKA MONDAY EVENING. ONCE AGAIN...UPPER LEVEL ENERGY WILL ENTER THE CENTRAL PLAINS FROM THE ROCKIES LATE IN THE DAY MONDAY...LEADING TO THE DEVELOPMENT OF THUNDERSTORMS. THERE IS SOME DISAGREEMENT AS TO WHERE THE UPPER LEVEL ENERGY WILL TRACK DURING THIS PERIOD SO CONFIDENCE IN LOCATION OF POPS IS LACKING ATTM. DECIDED TO CONFINE POPS INVOF OF THE FRONTAL BOUNDARY...IE...EASTERN CWA FOR MONDAY NIGHT. ON TUESDAY...EASTERLY WINDS WILL BECOME SOUTHERLY BY AFTERNOON AS HIGH PRESSURE DRIFTS EAST INTO THE UPPER MIDWEST. THE FRONTAL BOUNDARY WILL WASH OUT WHILE NORTHWESTERLY FLOW ALOFT CONTINUES. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL TRACK ACROSS THE REGION TUESDAY AFTERNOON AND TUESDAY NIGHT AS ANOTHER UPPER LEVEL DISTURBANCE TRACKS FROM THE CENTRAL AND NORTHERN ROCKIES ONTO THE CENTRAL PLAINS. LONG RANGE...TUESDAY NIGHT THROUGH SATURDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO THE EXTENDED PERIODS WITH ABUNDANT LOW LEVEL MOISTURE AND PERSISTENT WESTERLY AND NORTHWESTERLY FLOW ALOFT. NUMEROUS SHORTWAVES WILL TRACK ACROSS THE CENTRAL ROCKIES ACROSS THE CENTRAL PLAINS THROUGH THE PERIOD...LEADING TO A GOOD CHANCE FOR PRECIPITATION DURING THE PERIOD. TEMPERATURES WILL BE SEASONAL WITH HIGHS IN THE 80S AND LOWS IN THE UPPER 50S AND LOWER 60S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 635 PM CDT SAT JUL 20 2013 THUNDERSTORMS WILL SWEEP THE FORECAST AREA TONIGHT...AND EXIT BY 09Z. VFR IS EXPECTED THEREAFTER UNTIL 21Z SUNDAY AT WHICH TIME ISOLATED THUNDERSTORMS COULD REDEVELOP...WEST OF HIGHWAY 83. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...SPRINGER LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
550 AM CDT FRI JUL 19 2013 .UPDATE... ISSUED AT 541 AM CDT FRI JUL 19 2013 CONVECTION HAS DEVELOPED ACROSS PLATTE AND NANCE COUNTY AND MAY CONTINUE TO EXPAND ACROSS OUR NORTHERN CWA OVER THE NEXT FEW HOURS IF THE HRRR IS ACCURATE. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON THIS SITUATION AND WILL BE SENDING OUT AN UPDATED FORECAST SHORTLY TO INCLUDE THUNDERSTORMS THIS MORNING ACROSS NORTHERN ZONES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 339 AM CDT FRI JUL 19 2013 HOT CONDITIONS WILL PERSIST TODAY...BUT AT LEAST THERE IS FINALLY A SLIGHT CHANCE OF PRECIPITATION ACROSS PORTIONS OF THE FORECAST AREA. A FRONTAL BOUNDARY LOCATED OVER NORTHERN NEBRASKA EARLY THIS MORNING WILL SLIDE SOUTH AND INTO NORTHERN KANSAS BY LATER THIS AFTERNOON. THE AIR ALONG AND RIGHT BEHIND THIS FRONT REMAINS HOT AND THUS DO NOT EXPECT ANY RELIEF FROM THE HEAT TODAY. IN FACT...THE WIND WILL BECOME RATHER LIGHT IN CLOSE PROXIMITY TO THE FRONT AND MOISTURE WILL POOL ALONG THE FRONT MAKING FOR A MORE UNCOMFORTABLE STICKY DAY WITH LESS AIR FLOW TO KEEP YOU COOL. THERE SHOULD BE A FEW MORE CLOUDS THAN THE PAST SEVERAL DAYS GIVEN CONVERGENCE ALONG THE FRONT. THE EARLY MORNING RUNS OF THE HRRR WOULD INDICATE THE POTENTIAL FOR SHOWERS THIS MORNING...BUT MOST FORECAST MODELS HOLD OFF PRECIPITATION UNTIL AFTERNOON. THE HRRR HAS BEEN OVERDOING PRECIPITATION THIS MORNING THUS FAR BASED ON THE LACK OF RADAR ECHOS. HENCE WILL KEEP ACCUMULATING PRECIPITATION OUT OF THE FORECAST UNTIL AFTERNOON...BUT CAN NOT COMPLETELY RULE OUT SPRINKLES OR A VERY LIGHT SHOWER THIS MORNING NEAR THE SFC FRONT. TONIGHT...THE SFC FRONT WILL BE LOCATED OVER NORTHER KANSAS AND THIS IS WHERE OUR BEST CHANCE OF RAIN WILL BE...ALTHOUGH IT IS ONLY A SLIGHT CHANCE OF PRECIPITATION. WILL ALSO NEED TO KEEP AN EYE OUT TO THE NORTHWEST AS SHOWERS AND THUNDERSTORMS FROM SOUTHWEST SOUTH DAKOTA AND WESTERN NEBRASKA TRY TO MAKE IT INTO OUR NORTHERN MOST TIER OF COUNTIES AS WE NEAR DAWN. CURRENT THINKING BASED ON MOST FORECAST MODELS IS THAT THE NORTHERN CONVECTION WILL REMAIN NORTH OF OUR FORECAST AREA...BUT WORTH KEEPING AN EYE ON. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 339 AM CDT FRI JUL 19 2013 MAIN FORECAST CONCERNS WILL BE CHANCES FOR THUNDERSTORMS AND TEMPERATURES. NORTHWEST FLOW IS FORECAST TO REMAIN ACROSS THE PLAINS THROUGH THIS PERIOD. THERE ARE SEVERAL UPPER LEVEL WAVES THAT MOVE THROUGH THE NORTHWEST FLOW AND EACH OF THEM BRING ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA. AS IS TYPICAL OF THIS TYPE OF REGIME THE TIMING AND STRENGTH OF THESE WAVES PLAYS A LARGE PART IN WHERE PRECIPITATION WILL FALL. MODELS HAVE SLIGHTLY DIFFERENT TIMING OF THESE WAVES AS THEY MOVE THROUGH THE AREA. THIS GIVES THE RELATIVELY SMALL POPS FOR NEARLY EVERY PERIOD FOR AT LEAST A PORTION OF THE AREA. AT THIS TIME THE STRONGEST AND MOST LIKELY PERIOD FOR THERE TO BE SOME PRECIPITATION WILL BE DURING THE SATURDAY NIGHT THROUGH SUNDAY NIGHT TIME FRAME. AN UPPER LEVEL WAVE MOVES INTO THE AREA SATURDAY AND STRENGTHENS SATURDAY NIGHT. AS THE UPPER WAVE MOVES INTO THE AREA SATURDAY MORNING THERE IS A CHANCE FOR SOME THUNDERSTORMS IN THE NORTH...BUT THE MAIN THUNDERSTORMS ARE EXPECTED TO DEVELOP ON THE HIGH PLAINS DURING THE AFTERNOON AND MOVE INTO THE AREA DURING THE AFTERNOON AND EVENING. MUCAPE IS THE BEST DURING THE LATE AFTERNOON INTO THE EVENING AND EXPECT THERE COULD BE SOME STRONG TO SEVERE STORMS DURING THIS TIME. THE THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO SUNDAY AND SUNDAY NIGHT AS ANOTHER WAVE MOVES INTO THE AREA. THE SAME STORY CONTINUES TO PLAY OUT MONDAY THROUGH TUESDAY NIGHT AS A SERIES OF UPPER LEVEL WAVES MOVE THROUGH. THESE ARE A LITTLE WEAKER AND EXPECT THERE MAY BE SOME MORE SPOTTY PRECIPITATION OUT OF THESE UPPER WAVES. NOT EVERYONE WILL HAVE PRECIPITATION AS THESE SYSTEMS MOVE THROUGH. WEDNESDAY APPEARS TO BE DRY BEFORE MORE WEAK UPPER LEVEL WAVES MOVE INTO THE AREA AND SOME SLIGHT CHANCES FOR THUNDERSTORMS. TEMPERATURES WILL BE AROUND NORMAL OR JUST A LITTLE ABOVE DURING THIS TIME. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 541 AM CDT FRI JUL 19 2013 THERE ARE ESSENTIALLY TWO THINGS TO WATCH FOR. THE FIRST WILL BE A GRADUALLY SHIFTING WIND AS A FRONT PASSES THROUGH. EXPECT A SHIFT FROM SOUTHWEST...TO NORTH...TO NORTHEAST OVER THE COURSE OF THE MORNING. THE SECOND AREA OF CONCERN WILL CENTER AROUND THE SLIGHT CHANCE OF AN ISOLATED THUNDERSTORM. THE BEST CHANCE OF THUNDERSTORMS WOULD BE FROM LATE MORNING THROUGH MID AFTERNOON. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...WESELY SHORT TERM...WESELY LONG TERM...JCB AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS BUFFALO NY
348 PM EDT FRI JUL 19 2013 .SYNOPSIS... SHOWERS AND THUNDERSTORMS WILL DROP ACROSS THE REGION TONIGHT...WHICH WILL LINGER INTO SATURDAY. A COLD FRONT WILL DROP ACROSS THE REGION SATURDAY...BRINGING MUCH COOLER CONDITIONS FOR SUNDAY AND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... FOR THE REMAINDER OF THIS AFTERNOON HOT AND WINDY CONDITIONS WILL PERSIST ACROSS THE REGION. AN UPPER LEVEL TROF SOUTH OF HUDSON BAY WILL DIVE TOWARD THE UPPER LAKES THROUGH TONIGHT...PUSHING AN ASSOCIATED COLD FRONTAL BOUNDARY TOWARD OUR REGION. WHILE THE FRONT ITSELF WILL REMAIN WELL UPSTREAM...THIS WILL RESULT IN A TIGHTENING PRESSURE GRADIENT. THE BUFFALO VAD WIND PROFILE ALREADY SHOWS 40 KNOT WINDS AT 925 MB...WITH THESE WINDS FORECAST TO INCREASE SLIGHTLY FROM WEST TO EAST THROUGH THIS EVENING. THESE SOUTHWEST WINDS SHOULD FAIRLY READILY MIX TO THE SURFACE...WITH THE LAKE BREEZE ENHANCING THIS FLOW TO THE NORTHEAST OF THE LAKES. THE WINDIEST CONDITIONS SHOULD BE ACROSS THE NIAGARA FRONTIER AND IMMEDIATE LAKE ERIE SHORELINE...WHICH INCLUDES THE BUFFALO METRO AREA. GUSTS SHOULD GENERALLY RUN IN THE 40 TO 45 MPH RANGE IN THIS AREA...WITH PEAK GUSTS LIKELY TO TOP OUT NEAR 50 MPH. EXPECT THAT WITH THE FULL FOLIAGE...THIS WILL RESULT IN A FEW DOWNED TREE LIMBS...WITH SOME SPOTTY POWER OUTAGES POSSIBLE. ELSEWHERE WILL BE BREEZY AS WELL...BUT INTERIOR LOCATIONS WILL GENERALLY LESS WINDY. THE OTHER BIG ISSUE WILL SIMPLY BE THE HOT WEATHER. THE SW FLOW OFF THE LAKE SHOULD HOLD TEMPERATURES 90 IN THE BUFFALO AREA...BUT ROCHESTER EASTWARD THIS FLOW WILL DOWNSLOPE AND ADD A FEW MORE DEGREES TO THE ALREADY HOT WEATHER. FOR MANY THIS WILL BE THE HOTTEST DAY SO FAR...WITH HIGHS IN THE MID 90S. THIS COMBINED WITH DEW POINTS IN THE LOWER 70S WILL RESULT IN HEAT INDEX VALUES OVER 100 FOR ROCHESTER AND IN THE NORTHERN GENESEE VALLEY AND FINGER LAKES REGIONS. OTHERWISE...EXPECT WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER AND EASTERN LAKE ONTARIO REGION TO DISSIPATE TOWARD SUNSET...AS DAYTIME HEATING DIMINISHES AND AS WINDS INCREASE MIXING AND EXPAND THE LAKE SHADOWING. FOR TONIGHT AND INTO SATURDAY...THE FOCUS WILL SHIFT TO THE POTENTIAL FOR SEVERE WEATHER AND FOR LOCALLY HEAVY RAINFALL. THIS WILL LIKELY COME IN TWO WAVES. THE FIRST CAN ALREADY BE SEEN CLEARLY THROUGH MID-AFTERNOON...WITH THIS AREA ASSOCIATED WITH A LINE OF THUNDERSTORMS ACROSS LAKE HURON AND EXTENDING EAST INTO SOUTHERN ONTARIO PROVINCE. THIS INITIAL WAVE WILL TRACK TOWARD OUR REGION...BUT GIVEN THE STRONG SW FLOW ACROSS THE LAKES WILL PROBABLY CAUSE IT TO WEAKEN AS IT TRIES TO MOVE INTO OUR REGION. HIGHER RESOLUTION GUIDANCE IS IN GENERAL AGREEMENT WITH THE NAM/RGEM/HRRR ALL SHOWING THIS GENERAL TREND. THERE IS STILL A POSSIBILITY THAT THIS WILL HOLD TOGETHER LONG ENOUGH TO HAVE SOME IMPACT ON OUR CWA...WITH THE SAINT LAWRENCE RIVER AND NORTH COUNTRY AND POSSIBLY PORTIONS OF THE NIAGARA FRONTIER THE AREAS TO WATCH. IT WILL BE TRICKY...SINCE THE LINE WILL PROBABLY BE QUITE IMPRESSIVE JUST UPSTREAM OF THE LAKE BREEZE...WITH BOWING LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WINDS. THIS INITIAL LINE WILL IMPACT OUR REGION BETWEEN 700 PM AND 1000 PM. BEHIND THIS...IS A SECONDARY LINE OF THUNDERSTORMS DEVELOPING ALONG WHAT APPEARS TO BE A PRE-FRONTAL TROF WIND SHIFT BOUNDARY. 00/12Z RUNS OF THE NAM/RGEM AND RECENT RUNS OF THE HRRR CONTINUE TO SUGGEST THAT THIS AREA WILL EXPAND...AND EVENTUALLY DROP ACROSS OUR REGION DURING THE OVERNIGHT HOURS. THE LATER TIMING...AND CLOSER PROXIMITY TO THE SHORTWAVE WILL MAKE THIS FEATURE MORE LIKELY TO HOLD TOGETHER AS IT DROPS ACROSS THE LAKES AND ACROSS WESTERN NEW YORK LATE TONIGHT AND INTO SATURDAY MORNING. THIS TIMING IS CLIMATOLOGICALLY NOT FAVORABLE FOR SEVERE WEATHER...BUT GIVEN THE SIGNIFICANT AMOUNT OF NIGHTTIME INSTABILITY...AND STILL A FAIR AMOUNT OF SHEAR...IT WILL BEAR A RADAR WATCH IF IT DOES INDEED DEVELOP AS FORECAST. IN ADDITION TO THE SEVERE WEATHER THREAT...THERE WILL ALSO BE A RISK FOR LOCALLY HEAVY DOWNPOURS. PRECIPITABLE WATER VALUES WILL BE 1.75 TO 2.00 INCHES...AND WHILE STORMS WILL LIKELY BE MOVING...LARGE AREAS OF CONVECTION OR BRIEF TRAINING COULD QUICKLY ADD UP AND LEAD TO LOCALIZED FLOODING. ON SATURDAY...EXPECT MOST OF THE SHOWERS AND THUNDERSTORM ACTIVITY TO SLIDE TO THE SOUTH AND EAST OF THE AREA LATE MORNING AND INTO THE AFTERNOON HOURS. THE ACTUAL FRONTAL BOUNDARY WILL NOT CROSS UNTIL LATER IN THE DAY...BUT MUCH DRIER AIR WILL MOVE IN BEHIND THE PRE-FRONTAL TROF WITH ONLY MARGINAL CHANCE FOR ANY SHOWERS OR THUNDERSTORMS ALONG THE FRONT ITSELF WHICH WILL CROSS LATE IN THE DAY SATURDAY. WITH COOLER AIR MOVING IN AND LINGERING PRECIPITATION...TEMPERATURES WILL BE NOTABLY COOLER ON SATURDAY...WITH HIGHS MAINLY IN THE LOWER 80S. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... BY SATURDAY EVENING...MOST OF THE 12Z GUIDANCE PACKAGES ARE IN GOOD AGREEMENT THAT THE COLD FRONTAL ZONE AND THE BULK OF ITS ASSOCIATED PRECIPITATION WILL HAVE SLIPPED TO OUR SOUTH...SAVE FOR THE NAM WHICH IS A SLOWER OUTLIER. AS THIS PARTICULAR MODEL HAS SHOWN SOME RUN-TO-RUN INCONSISTENCIES WITH THE TIMING OF THE FRONT OVER THE PAST DAY OR SO...WILL DISREGARD IT IN FAVOR OF THE FASTER GFS/ GEM/ECMWF CONSENSUS AND OUR EXISTING CONTINUITY...ALL OF WHICH ADVERTISE A GENERALLY DRY NIGHT. IN THE WAKE OF THE FRONT...A HIGHLY ANTICIPATED COOLER AND DRIER AIRMASS WILL SPREAD SOUTH ACROSS OUR AREA THROUGH THE COURSE OF THE NIGHT...FINALLY BRINGING SOME MUCH WELCOMED RELIEF FROM THE TROPICAL HEAT AND HUMIDITY LEVELS OF THE PAST WEEK. EXPECT OVERNIGHT LOWS TO DROP TO THE MID 50S TO LOWER 60S...WHILE SURFACE DEWPOINTS FALL BACK TO MUCH MORE COMFORTABLE LEVELS IN THE 50S. WITH THE WATERS OF THE LOWER GREAT LAKES NOW IN THE MID TO UPPER 70S /OR AROUND +25C/...AND THE INCOMING COOLER AIRMASS EVENTUALLY FEATURING 850 MB TEMPS OF AROUND +10C BY LATER IN THE NIGHT...WE MAY WELL SEE SOME LAKE EFFECT CLOUDINESS DEVELOP SOUTH OF THE LAKES OVERNIGHT...THOUGH THE INCOMING AIRMASS WILL LIKELY REMAIN TOO DRY AND FEATURE TOO LOW OF A SUBSIDENCE INVERSION TO SUPPORT ANY LAKE EFFECT SHOWERS. SUNDAY AND SUNDAY NIGHT...SURFACE HIGH PRESSURE WILL SETTLE DIRECTLY ACROSS THE LOWER LAKES AND NEW YORK STATE IN THE WAKE OF THE COLD FRONT. COUPLED WITH STRONG MIDSUMMER DIURNAL EFFECTS...THIS SHOULD RESULT IN ANY LAKE EFFECT CLOUDS FROM SATURDAY NIGHT BREAKING UP DURING THE COURSE OF SUNDAY MORNING...LEADING TO A DECENT AMOUNT OF SUNSHINE EVERYWHERE FOR THE AFTERNOON. MEANWHILE...850 MB TEMPS RANGING FROM +9C NORTH TO +13C SOUTH SHOULD SUPPORT RATHER PLEASANT HIGHS IN THE MID TO UPPER 70S...WHILE DEWPOINTS CONTINUE TO LOWER TO THE 50-55 DEGREE RANGE WITH DIURNAL MIXING. THE COOLER AND QUIET WEATHER WILL THEN CONTINUE INTO SUNDAY NIGHT...WHEN LOWS SHOULD RANGE THROUGH THE 50S IN MOST LOCATIONS...WITH SOME UPPER 40S EVEN POSSIBLE ACROSS PORTIONS OF THE NORTH COUNTRY. WITH THE LOW LEVEL FLOW VEERING MORE EASTERLY...DO NOT EXPECT LAKE EFFECT CLOUDINESS TO BE A PROBLEM FOR SUNDAY NIGHT...THOUGH THERE WILL PROBABLY BE SOME INCREASE IN MID/HIGH CLOUDS OVERNIGHT IN ADVANCE OF A MODEST SHORTWAVE TROUGH THAT WILL BE WORKING INTO THE CENTRAL GREAT LAKES. MONDAY AND MONDAY NIGHT...THE SURFACE HIGH WILL SLIDE EAST ACROSS NEW ENGLAND AND OUT TO SEA...WHILE THE AFOREMENTIONED SHORTWAVE TROUGH TO OUR WEST SETTLES ACROSS THE LOWER LAKES AND NY/PA...WHILE ALSO SPAWNING SOME SEMBLANCE OF A WEAK SURFACE REFLECTION. WHILE THE VARIOUS GUIDANCE PACKAGES STILL DIFFER WITH RESPECT TO HOW FAST THIS SYSTEM ARRIVES AND EXACTLY HOW WELL DEVELOPED IT WILL BE...ALL HAVE CONTINUED THE RECENT TREND TOWARD A FASTER AND SOMEWHAT MORE DEVELOPED SYSTEM...WITH A PLUME OF DEEPER MOISTURE AND WEAK TO MODEST ISENTROPIC LIFT EVENTUALLY ADVECTING INTO OUR AREA BETWEEN MONDAY AFTERNOON AND MONDAY NIGHT. WITH THIS AND OUR EXISTING CONTINUITY OF A TOTALLY DRY FORECAST BOTH IN MIND...HAVE ELECTED TO GRADUALLY INTRODUCE SOME LOWER CHANCE POPS INTO AREAS SOUTH OF LAKE ONTARIO MONDAY AFTERNOON...BEFORE BRINGING HIGHER CHANCE RANGE POPS INTO THE ENTIRE AREA MONDAY NIGHT. THE HIGHEST PRECIPITATION CHANCES WILL BE FOCUSED ACROSS OUR FINGER LAKES AND NORTH COUNTRY ZONES... WHICH WILL BE CLOSEST TO THE BEST AREA OF DEEPER MOISTURE AND ISENTROPIC LIFT. TEMPS THROUGH THIS LATTER PORTION OF THE PERIOD WILL RETURN TO MIDSUMMER NORMS GIVEN THE WEAK WARM AIR ADVECTION PATTERN...WITH DAYTIME HIGHS OF AROUND 80 EXPECTED ON MONDAY... FOLLOWED BY LOWS IN THE LOWER TO MID 60S MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... IN THE LONG TERM PORTION OF THE FORECAST...THE LARGE-SCALE WEATHER PATTERN ACROSS NORTH AMERICA WILL REVERT TO ONE WE HAVE BEEN MORE FAMILIAR WITH FOR THE BULK OF THE SPRING AND SUMMER...THAT OF A BROAD RIDGE OVER THE ROCKIES AND WESTERN PLAINS...WITH A CORRESPONDING BROAD DOWNSTREAM TROUGH DEVELOPING OVER THE GREAT LAKES AND NORTHEAST. THIS CHANGE IN THE PATTERN WILL RESULT IN AN EXTENDED PERIOD OF MORE NORMAL SUMMERTIME TEMPERATURES FOR OUR REGION...WITH DAILY HIGHS AVERAGING WITHIN A FEW DEGREES OF 80 EACH DAY...AND NIGHTTIME LOWS GENERALLY RANGING IN THE LOWER TO MID 60S. WITH RESPECT TO PRECIPITATION CHANCES...THE FORECAST PICTURE REMAINS CONSIDERABLY MORE MUDDLED. UNDER THE EXPECTED LARGE-SCALE FLOW REGIME...NUMEROUS PIECES OF SHORTWAVE ENERGY SHOULD ROTATE THROUGH THE DEVELOPING TROUGH AND LEAD TO PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS...HOWEVER THE MEDIUM RANGE GUIDANCE REMAINS ALL OVER THE MAP WITH RESPECT TO THE TIMING AND STRENGTH OF THESE FEATURES. WITH THIS IN MIND...HAVE JUST CONTINUED TO BROADBRUSH SOME LOW CHANCE POPS ACROSS THE ENTIRE PERIOD FOR NOW...AND WILL WAIT UNTIL BETTER MODEL AGREEMENT DEVELOPS BEFORE TRYING TO PROVIDE MORE REFINED/DETAILED PRECIPITATION PROBABILITIES AND TIMING. ALL THIS SAID...THIS PERIOD LOOKS TO BE FAR FROM A WASHOUT AT THIS TIME... WITH ANY SHOTS OF SHOWERS/STORMS LIKELY TO ALTERNATE WITH FREQUENT DRY PERIODS. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... FOR THE 18Z TAF CYCLE...GUSTY SW WINDS TO BE THE MAIN IMPACT FOR THIS AFTERNOON...WITH BUF/IAG/ROC/ART ALL SEEING PREVAILING GUSTS IN THE 30 TO 35 KT RANGE. WIDELY SCATTERED THUNDERSTORMS MAY BRIEFLY IMPACT JHW. AFTER THIS...A LINE OF THUNDERSTORMS WILL APPROACH FROM THE WEST 23Z. THIS AREA WILL PROBABLY WEAKEN AS IT MOVES INTO OUR REGION...BUT MAY HOLD TOGETHER LONG ENOUGH TO IMPACT IAG/ART...AND POSSIBLY BUF/ROC DURING THE EVENING HOURS. STEADIER THUNDERSTORMS ARE LIKELY LATE TONIGHT AS A LARGER AREA IS FORECAST TO DROP ACROSS THE REGION. ALL THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND WIND SHIFTS...WITH HEAVY RAIN LOWERING VSBY TO 1SM. STORMS WILL DROP FROM N-S LATE TONIGHT AND INTO SATURDAY MORNING...WITH CONDITIONS IMPROVING TO VFR. OUTLOOK... SATURDAY NIGHT THROUGH MONDAY MORNING...VFR. MONDAY AFTERNOON THROUGH WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS. && .MARINE... WINDS HAVE PICKED UP THROUGH THE EARLY AFTERNOON HOURS ACROSS MOST OF THE WATERS...WITH WINDS STRONGEST NEAR THE LAKE SHORES. THESE WILL CONTINUE THROUGH THIS EVENING...AS A STRONG LOW LEVEL JET REMAINS ACROSS THE REGION. WINDS WILL DIMINISH FROM WEST TO EAST LATER TONIGHT...MORE QUICKLY ACROSS AREAS NEAR LAND WHERE THE LOSS OF DAYTIME HEATING WILL RESULT IN LESS MIXING. WAVES ON THE NORTHEAST SHORES WILL TAKE A BIT TO DROP OFF ON BOTH OF THE LAKES. THE OTHER ISSUE FOR THIS EVENING AND TONIGHT WILL BE THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS ON THE WATERS. WINDS WILL DIMINISH SATURDAY AND ONWARD WITH NO HEADLINES ANTICIPATED. && .CLIMATE... HOT AND HUMID WEATHER WILL CONTINUE THROUGH TODAY AND TEMPERATURES WILL APPROACH RECORD HIGHS THIS AFTERNOON...THOUGH THE ONLY SITE THAT IS EXPECTED TO AT LEAST TIE IT/S RECORD HIGH IS ROCHESTER. HOWEVER...WITH READINGS IN THE UPPER 70S THIS FRIDAY MORNING...RECORD WARM LOWS SHOULD BE BROKEN AT ALL THREE LOCATIONS BELOW. HERE ARE THE RECORDS FOR THE REMAINDER OF THE WORK WEEK. BUFFALO.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 75 ROCHESTER.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 95 75 WATERTOWN.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 72 HERE ARE THE MONTHLY AND ALL TIME RECORD LOW MINIMUMS... BUFFALO.. JULY.. 78 1897 ALL TIME.. 79 2006 ROCHESTER.. JULY (ALL TIME)..81 1936 AND 1940 WATERTOWN.. JULY (ALL TIME).. 79 2011 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001>006-011- 013-014. WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001-002-010- 011-019-085. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ030-042-043. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LOZ044- 045. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...JJR LONG TERM...JJR AVIATION...APFFEL MARINE...APFFEL CLIMATE...HITCHCOCK/WOOD/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
302 PM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY...WITH PLENTY OF SUNSHINE AND MAINLY RAIN FREE CONDITIONS TODAY. THERE WILL BE JUST AN ISOLATED STORM WELL INLAND FROM THE LAKES THIS AFTERNOON. THERE WILL ALSO BE A GUSTY SOUTHWESTERLY WIND TODAY AHEAD OF A COLD FRONT...WITH THE COLD FRONT BRINGING SOME SHOWERS AND THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY ACROSS THE REGION. COMFORTABLE CONDITIONS WILL FINALLY RETURN BEHIND THE FRONT FOR SUNDAY. && .NEAR TERM /THROUGH SATURDAY/... FOR THE REMAINDER OF THIS AFTERNOON HOT AND WINDY CONDITIONS WILL PERSIST ACROSS THE REGION. AN UPPER LEVEL TROF SOUTH OF HUDSON BAY WILL DIVE TOWARD THE UPPER LAKES THROUGH TONIGHT...PUSHING AN ASSOCIATED COLD FRONTAL BOUNDARY TOWARD OUR REGION. WHILE THE FRONT ITSELF WILL REMAIN WELL UPSTREAM...THIS WILL RESULT IN A TIGHTENING PRESSURE GRADIENT. THE VAD WIND PROFILE ALREADY SHOWS 40 KNOT WINDS AT 925 MB...AND THESE ARE FORECAST TO INCREASE A BIT MORE THROUGH SUNSET FROM WEST TO EAST. THESE SOUTHWEST WINDS SHOULD FAIRLY READILY MIX TO THE SURFACE...WITH THE LAKE BREEZE ENHANCING THIS FLOW TO THE NORTHEAST OF THE LAKES. THE WINDIEST CONDITIONS SHOULD BE ACROSS THE NIAGARA FRONTIER AND IMMEDIATE LAKE ERIE SHORELINE...WHICH INCLUDES THE BUFFALO METRO AREA. GUSTS SHOULD GENERALLY RUN IN THE 40 TO 45 MPH RANGE IN THIS AREA...WITH PEAK GUSTS LIKELY TO TOP OUT NEAR 50 MPH. EXPECT THAT WITH THE FULL FOLIAGE...THIS WILL RESULT IN A FEW DOWNED TREE LIMBS...WITH SOME SPOTTY POWER OUTAGES POSSIBLE. ELSEWHERE WILL BE BREEZY AS WELL...BUT INTERIOR LOCATIONS WILL GENERALLY LESS WINDY. THE OTHER BIG ISSUE WILL SIMPLY BE THE HOT WEATHER. THE SW FLOW OFF THE LAKE SHOULD HOLD TEMPERATURES 90 IN THE BUFFALO AREA...BUT ROCHESTER EASTWARD THIS FLOW WILL DOWNSLOPE AND ADD A FEW MORE DEGREES TO THE ALREADY HOT WEATHER. FOR MANY THIS WILL BE THE HOTTEST DAY SO FAR...WITH HIGHS IN THE MID 90S. THIS COMBINED WITH DEW POINTS IN THE LOWER 70S WILL RESULT IN HEAT INDEX VALUES OVER 100 FOR ROCHESTER AND IN THE NORTHERN GENESEE VALLEY AND FINGER LAKES REGIONS. OTHERWISE...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER AND EASTERN LAKE ONTARIO REGION TO DISSIPATE TOWARD THIS EVENING...AS DAYTIME HEATING DIMINISHES AND AS WINDS INCREASE MIXING AND EXPAND THE LAKE SHADOWING. FOR TONIGHT AND INTO SATURDAY...THE FOCUS WILL SHIFT TO THE POTENTIAL FOR SEVERE WEATHER...WITH LOCALLY HEAVY DOWNPOURS. THIS WILL LIKELY COME IN TWO WAVES. THE FIRST CAN ALREADY BE SEEN CLEARLY EARLY THIS AFTERNOON...ASSOCIATED WITH A LINE OF THUNDERSTORMS DEVELOPING ACROSS CENTRAL MICHIGAN TO LAKE HURON. THIS INITIAL WAVE WILL TRACK TOWARD OUR REGION THROUGH THE AFTERNOON HOURS...BUT GIVEN THE STRONG SW FLOW ACROSS THE LAKES EXPECT IT WILL WEAKEN RAPIDLY AS IT APPROACHES OUR REGION. HIGHER RESOLUTION GUIDANCE IS IN GENERAL AGREEMENT WITH THE NAM/RGEM/HRRR ALL SHOWING THIS GENERAL TREND. THERE IS STILL A POSSIBILITY THAT THIS WILL HOLD TOGETHER LONG ENOUGH TO HAVE SOME IMPACT ON OUR CWA...WITH THE SAINT LAWRENCE RIVER AND NORTH COUNTRY AND POSSIBLY PORTIONS OF THE NIAGARA FRONTIER THE AREAS TO WATCH. IT WILL BE TRICKY...SINCE THE LINE WILL PROBABLY BE QUITE IMPRESSIVE JUST UPSTREAM OF THE LAKE BREEZE...WITH BOWING LINE SEGMENTS CAPABLE OF PRODUCING STRONG WINDS. THIS INITIAL LINE WILL IMPACT OUR REGION BETWEEN 700 PM AND 1000 PM. BEHIND THIS...IS A SECONDARY LINE OF THUNDERSTORMS DEVELOPING ALONG WHAT APPEARS TO BE A PRE-FRONTAL TROF WIND SHIFT BOUNDARY. 00/12Z RUNS OF THE NAM/RGEM AND RECENT RUNS OF THE HRRR CONTINUE TO SUGGEST THAT THIS AREA WILL EXPAND...AND EVENTUALLY DROP ACROSS OUR REGION DURING THE OVERNIGHT HOURS. THE LATER TIMING...AND CLOSER PROXIMITY TO THE SHORTWAVE WILL MAKE THIS FEATURE MORE LIKELY TO HOLD TOGETHER AS IT DROPS ACROSS THE LAKES AND ACROSS WESTERN NEW YORK LATE TONIGHT AND INTO SATURDAY MORNING. THIS TIMING IS CLIMATOLOGICALLY NOT FAVORABLE FOR SEVERE WEATHER...BUT GIVEN THE SIGNIFICANT AMOUNT OF NIGHTTIME INSTABILITY...AND STILL A FAIR AMOUNT OF SHEAR...IT WILL BEAR A RADAR WATCH IF IT DOES INDEED DEVELOP AS FORECAST. IN ADDITION TO THE SEVERE WEATHER THREAT...THERE WILL ALSO BE A RISK FOR LOCALLY HEAVY DOWNPOURS. PRECIPITABLE WATER VALUES WILL BE 1.75 TO 2.00 INCHES...AND WHILE STORMS WILL LIKELY BE MOVING...LARGE AREAS OF CONVECTION OR BRIEF TRAINING COULD QUICKLY ADD UP AND LEAD TO LOCALIZED FLOODING. ON SATURDAY...EXPECT MOST OF THE SHOWERS AND THUNDERSTORM ACTIVITY TO SLIDE TO THE SOUTH AND EAST OF THE AREA LATE MORNING AND INTO THE AFTERNOON HOURS. THE ACTUAL FRONTAL BOUNDARY WILL NOT CROSS UNTIL LATER IN THE DAY...BUT MUCH DRIER AIR WILL MOVE IN BEHIND THE PRE-FRONTAL TROF WITH ONLY MARGINAL CHANCE FOR ANY SHOWERS OR THUNDERSTORMS ALONG THE FRONT ITSELF WHICH WILL CROSS LATE IN THE DAY SATURDAY. WITH COOLER AIR MOVING IN AND LINGERING PRECIPITATION...TEMPERATURES WILL BE NOTABLY COOLER ON SATURDAY...WITH HIGHS MAINLY IN THE LOWER 80S. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... BY SATURDAY EVENING...MOST OF THE 12Z GUIDANCE PACKAGES ARE IN GOOD AGREEMENT THAT THE COLD FRONTAL ZONE AND THE BULK OF ITS ASSOCIATED PRECIPITATION WILL HAVE SLIPPED TO OUR SOUTH...SAVE FOR THE NAM WHICH IS A SLOWER OUTLIER. AS THIS PARTICULAR MODEL HAS SHOWN SOME RUN-TO-RUN INCONSISTENCIES WITH THE TIMING OF THE FRONT OVER THE PAST DAY OR SO...WILL DISREGARD IT IN FAVOR OF THE FASTER GFS/ GEM/ECMWF CONSENSUS AND OUR EXISTING CONTINUITY...ALL OF WHICH ADVERTISE A GENERALLY DRY NIGHT. IN THE WAKE OF THE FRONT...A HIGHLY ANTICIPATED COOLER AND DRIER AIRMASS WILL SPREAD SOUTH ACROSS OUR AREA THROUGH THE COURSE OF THE NIGHT...FINALLY BRINGING SOME MUCH WELCOMED RELIEF FROM THE TROPICAL HEAT AND HUMIDITY LEVELS OF THE PAST WEEK. EXPECT OVERNIGHT LOWS TO DROP TO THE MID 50S TO LOWER 60S...WHILE SURFACE DEWPOINTS FALL BACK TO MUCH MORE COMFORTABLE LEVELS IN THE 50S. WITH THE WATERS OF THE LOWER GREAT LAKES NOW IN THE MID TO UPPER 70S /OR AROUND +25C/...AND THE INCOMING COOLER AIRMASS EVENTUALLY FEATURING 850 MB TEMPS OF AROUND +10C BY LATER IN THE NIGHT...WE MAY WELL SEE SOME LAKE EFFECT CLOUDINESS DEVELOP SOUTH OF THE LAKES OVERNIGHT...THOUGH THE INCOMING AIRMASS WILL LIKELY REMAIN TOO DRY AND FEATURE TOO LOW OF A SUBSIDENCE INVERSION TO SUPPORT ANY LAKE EFFECT SHOWERS. SUNDAY AND SUNDAY NIGHT...SURFACE HIGH PRESSURE WILL SETTLE DIRECTLY ACROSS THE LOWER LAKES AND NEW YORK STATE IN THE WAKE OF THE COLD FRONT. COUPLED WITH STRONG MIDSUMMER DIURNAL EFFECTS...THIS SHOULD RESULT IN ANY LAKE EFFECT CLOUDS FROM SATURDAY NIGHT BREAKING UP DURING THE COURSE OF SUNDAY MORNING...LEADING TO A DECENT AMOUNT OF SUNSHINE EVERYWHERE FOR THE AFTERNOON. MEANWHILE...850 MB TEMPS RANGING FROM +9C NORTH TO +13C SOUTH SHOULD SUPPORT RATHER PLEASANT HIGHS IN THE MID TO UPPER 70S...WHILE DEWPOINTS CONTINUE TO LOWER TO THE 50-55 DEGREE RANGE WITH DIURNAL MIXING. THE COOLER AND QUIET WEATHER WILL THEN CONTINUE INTO SUNDAY NIGHT...WHEN LOWS SHOULD RANGE THROUGH THE 50S IN MOST LOCATIONS...WITH SOME UPPER 40S EVEN POSSIBLE ACROSS PORTIONS OF THE NORTH COUNTRY. WITH THE LOW LEVEL FLOW VEERING MORE EASTERLY...DO NOT EXPECT LAKE EFFECT CLOUDINESS TO BE A PROBLEM FOR SUNDAY NIGHT...THOUGH THERE WILL PROBABLY BE SOME INCREASE IN MID/HIGH CLOUDS OVERNIGHT IN ADVANCE OF A MODEST SHORTWAVE TROUGH THAT WILL BE WORKING INTO THE CENTRAL GREAT LAKES. MONDAY AND MONDAY NIGHT...THE SURFACE HIGH WILL SLIDE EAST ACROSS NEW ENGLAND AND OUT TO SEA...WHILE THE AFOREMENTIONED SHORTWAVE TROUGH TO OUR WEST SETTLES ACROSS THE LOWER LAKES AND NY/PA...WHILE ALSO SPAWNING SOME SEMBLANCE OF A WEAK SURFACE REFLECTION. WHILE THE VARIOUS GUIDANCE PACKAGES STILL DIFFER WITH RESPECT TO HOW FAST THIS SYSTEM ARRIVES AND EXACTLY HOW WELL DEVELOPED IT WILL BE...ALL HAVE CONTINUED THE RECENT TREND TOWARD A FASTER AND SOMEWHAT MORE DEVELOPED SYSTEM...WITH A PLUME OF DEEPER MOISTURE AND WEAK TO MODEST ISENTROPIC LIFT EVENTUALLY ADVECTING INTO OUR AREA BETWEEN MONDAY AFTERNOON AND MONDAY NIGHT. WITH THIS AND OUR EXISTING CONTINUITY OF A TOTALLY DRY FORECAST BOTH IN MIND...HAVE ELECTED TO GRADUALLY INTRODUCE SOME LOWER CHANCE POPS INTO AREAS SOUTH OF LAKE ONTARIO MONDAY AFTERNOON...BEFORE BRINGING HIGHER CHANCE RANGE POPS INTO THE ENTIRE AREA MONDAY NIGHT. THE HIGHEST PRECIPITATION CHANCES WILL BE FOCUSED ACROSS OUR FINGER LAKES AND NORTH COUNTRY ZONES... WHICH WILL BE CLOSEST TO THE BEST AREA OF DEEPER MOISTURE AND ISENTROPIC LIFT. TEMPS THROUGH THIS LATTER PORTION OF THE PERIOD WILL RETURN TO MIDSUMMER NORMS GIVEN THE WEAK WARM AIR ADVECTION PATTERN...WITH DAYTIME HIGHS OF AROUND 80 EXPECTED ON MONDAY... FOLLOWED BY LOWS IN THE LOWER TO MID 60S MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... IN THE LONG TERM PORTION OF THE FORECAST...THE LARGE-SCALE WEATHER PATTERN ACROSS NORTH AMERICA WILL REVERT TO ONE WE HAVE BEEN MORE FAMILIAR WITH FOR THE BULK OF THE SPRING AND SUMMER...THAT OF A BROAD RIDGE OVER THE ROCKIES AND WESTERN PLAINS...WITH A CORRESPONDING BROAD DOWNSTREAM TROUGH DEVELOPING OVER THE GREAT LAKES AND NORTHEAST. THIS CHANGE IN THE PATTERN WILL RESULT IN AN EXTENDED PERIOD OF MORE NORMAL SUMMERTIME TEMPERATURES FOR OUR REGION...WITH DAILY HIGHS AVERAGING WITHIN A FEW DEGREES OF 80 EACH DAY...AND NIGHTTIME LOWS GENERALLY RANGING IN THE LOWER TO MID 60S. WITH RESPECT TO PRECIPITATION CHANCES...THE FORECAST PICTURE REMAINS CONSIDERABLY MORE MUDDLED. UNDER THE EXPECTED LARGE-SCALE FLOW REGIME...NUMEROUS PIECES OF SHORTWAVE ENERGY SHOULD ROTATE THROUGH THE DEVELOPING TROUGH AND LEAD TO PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS...HOWEVER THE MEDIUM RANGE GUIDANCE REMAINS ALL OVER THE MAP WITH RESPECT TO THE TIMING AND STRENGTH OF THESE FEATURES. WITH THIS IN MIND...HAVE JUST CONTINUED TO BROADBRUSH SOME LOW CHANCE POPS ACROSS THE ENTIRE PERIOD FOR NOW...AND WILL WAIT UNTIL BETTER MODEL AGREEMENT DEVELOPS BEFORE TRYING TO PROVIDE MORE REFINED/DETAILED PRECIPITATION PROBABILITIES AND TIMING. ALL THIS SAID...THIS PERIOD LOOKS TO BE FAR FROM A WASHOUT AT THIS TIME... WITH ANY SHOTS OF SHOWERS/STORMS LIKELY TO ALTERNATE WITH FREQUENT DRY PERIODS. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... FOR THE 18Z TAF CYCLE...GUSTY SW WINDS TO BE THE MAIN IMPACT FOR THIS AFTERNOON...WITH BUF/IAG/ROC/ART ALL SEEING PREVAILING GUSTS IN THE 30 TO 35 KT RANGE. WIDELY SCATTERED THUNDERSTORMS MAY BRIEFLY IMPACT JHW. AFTER THIS...A LINE OF THUNDERSTORMS WILL APPROACH FROM THE WEST 23Z. THIS AREA WILL PROBABLY WEAKEN AS IT MOVES INTO OUR REGION...BUT MAY HOLD TOGETHER LONG ENOUGH TO IMPACT IAG/ART...AND POSSIBLY BUF/ROC DURING THE EVENING HOURS. STEADIER THUNDERSTORMS ARE LIKELY LATE TONIGHT AS A LARGER AREA IS FORECAST TO DROP ACROSS THE REGION. ALL THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND WIND SHIFTS...WITH HEAVY RAIN LOWERING VSBY TO 1SM. STORMS WILL DROP FROM N-S LATE TONIGHT AND INTO SATURDAY MORNING...WITH CONDITIONS IMPROVING TO VFR. OUTLOOK... SATURDAY NIGHT THROUGH MONDAY MORNING...VFR. MONDAY AFTERNOON THROUGH WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS. && .MARINE... AN INCREASING PRESSURE GRADIENT WILL BRING GUSTY SOUTHWEST WINDS TODAY TO THE LAKES...ESPECIALLY LAKE ERIE AND ACROSS BOTH RIVERS. WINDS AND WAVES WILL BUILD TO SMALL CRAFT ADVISORY LEVELS THROUGH THE DAY TODAY...THEN LINGER AT THESE LEVELS THROUGH TONIGHT/EARLY SATURDAY. WILL CONTINUE WITH SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS OF LAKES ERIE AND ONTARIO...AS WELL AS THE NIAGARA RIVER AND SAINT LAWRENCE RIVER. A GREATER AND MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES WILL ARRIVE FOR TONIGHT AS A COLD FRONT MAKES ITS WAY ACROSS THE LOWER LAKES...BRINGING THE POTENTIAL FOR STRONGER TO POTENTIALLY SEVERE STORMS WITH LOCALLY STRONG WINDS AND HIGHER WAVES. CONDITIONS WILL RETURN TO BELOW SCA LATER ON SATURDAY AND REMAIN BELOW SCA THROUGH THE REMAINDER OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. && .CLIMATE... HOT AND HUMID WEATHER WILL CONTINUE THROUGH TODAY AND TEMPERATURES WILL APPROACH RECORD HIGHS THIS AFTERNOON...THOUGH THE ONLY SITE THAT IS EXPECTED TO AT LEAST TIE IT/S RECORD HIGH IS ROCHESTER. HOWEVER...WITH READINGS IN THE UPPER 70S THIS FRIDAY MORNING...RECORD WARM LOWS SHOULD BE BROKEN AT ALL THREE LOCATIONS BELOW. HERE ARE THE RECORDS FOR THE REMAINDER OF THE WORK WEEK. BUFFALO.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 75 ROCHESTER.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 95 75 WATERTOWN.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 72 HERE ARE THE MONTHLY AND ALL TIME RECORD LOW MINIMUMS... BUFFALO.. JULY.. 78 1897 ALL TIME.. 79 2006 ROCHESTER.. JULY (ALL TIME)..81 1936 AND 1940 WATERTOWN.. JULY (ALL TIME).. 79 2011 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001>006-011- 013-014. WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001-002-010- 011-019-085. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ030-042-043. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LOZ044- 045. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL SHORT TERM...JJR LONG TERM...JJR AVIATION...APFFEL MARINE...APFFEL/THOMAS CLIMATE...HITCHCOCK/WOOD/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
256 PM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY...WITH PLENTY OF SUNSHINE AND MAINLY RAIN FREE CONDITIONS TODAY. THERE WILL BE JUST AN ISOLATED STORM WELL INLAND FROM THE LAKES THIS AFTERNOON. THERE WILL ALSO BE A GUSTY SOUTHWESTERLY WIND TODAY AHEAD OF A COLD FRONT...WITH THE COLD FRONT BRINGING SOME SHOWERS AND THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY ACROSS THE REGION. COMFORTABLE CONDITIONS WILL FINALLY RETURN BEHIND THE FRONT FOR SUNDAY. && .NEAR TERM /THROUGH SATURDAY/... FOR THE REMAINDER OF THIS AFTERNOON HOT AND WINDY CONDITIONS WILL PERSIST ACROSS THE REGION. AN UPPER LEVEL TROF SOUTH OF HUDSON BAY WILL DIVE TOWARD THE UPPER LAKES THROUGH TONIGHT...PUSHING AN ASSOCIATED COLD FRONTAL BOUNDARY TOWARD OUR REGION. WHILE THE FRONT ITSELF WILL REMAIN WELL UPSTREAM...THIS WILL RESULT IN A TIGHTENING PRESSURE GRADIENT. THE VAD WIND PROFILE ALREADY SHOWS 40 KNOT WINDS AT 925 MB...AND THESE ARE FORECAST TO INCREASE A BIT MORE THROUGH SUNSET FROM WEST TO EAST. THESE SOUTHWEST WINDS SHOULD FAIRLY READILY MIX TO THE SURFACE...WITH THE LAKE BREEZE ENHANCING THIS FLOW TO THE NORTHEAST OF THE LAKES. THE WINDIEST CONDITIONS SHOULD BE ACROSS THE NIAGARA FRONTIER AND IMMEDIATE LAKE ERIE SHORELINE...WHICH INCLUDES THE BUFFALO METRO AREA. GUSTS SHOULD GENERALLY RUN IN THE 40 TO 45 MPH RANGE IN THIS AREA...WITH PEAK GUSTS LIKELY TO TOP OUT NEAR 50 MPH. EXPECT THAT WITH THE FULL FOLIAGE...THIS WILL RESULT IN A FEW DOWNED TREE LIMBS...WITH SOME SPOTTY POWER OUTAGES POSSIBLE. ELSEWHERE WILL BE BREEZY AS WELL...BUT INTERIOR LOCATIONS WILL GENERALLY LESS WINDY. THE OTHER BIG ISSUE WILL SIMPLY BE THE HOT WEATHER. THE SW FLOW OFF THE LAKE SHOULD HOLD TEMPERATURES 90 IN THE BUFFALO AREA...BUT ROCHESTER EASTWARD THIS FLOW WILL DOWNSLOPE AND ADD A FEW MORE DEGREES TO THE ALREADY HOT WEATHER. FOR MANY THIS WILL BE THE HOTTEST DAY SO FAR...WITH HIGHS IN THE MID 90S. THIS COMBINED WITH DEW POINTS IN THE LOWER 70S WILL RESULT IN HEAT INDEX VALUES OVER 100 FOR ROCHESTER AND IN THE NORTHERN GENESEE VALLEY AND FINGER LAKES REGIONS. OTHERWISE...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER AND EASTERN LAKE ONTARIO REGION TO DISSIPATE TOWARD THIS EVENING...AS DAYTIME HEATING DIMINISHES AND AS WINDS INCREASE MIXING AND EXPAND THE LAKE SHADOWING. FOR TONIGHT AND INTO SATURDAY...THE FOCUS WILL SHIFT TO THE POTENTIAL FOR SEVERE WEATHER...WITH LOCALLY HEAVY DOWNPOURS. THIS WILL LIKELY COME IN TWO WAVES. THE FIRST CAN ALREADY BE SEEN CLEARLY EARLY THIS AFTERNOON...ASSOCIATED WITH A LINE OF THUNDERSTORMS DEVELOPING ACROSS CENTRAL MICHIGAN TO LAKE HURON. THIS INITIAL WAVE WILL TRACK TOWARD OUR REGION THROUGH THE AFTERNOON HOURS...BUT GIVEN THE STRONG SW FLOW ACROSS THE LAKES EXPECT IT WILL WEAKEN RAPIDLY AS IT APPROACHES OUR REGION. HIGHER RESOLUTION GUIDANCE IS IN GENERAL AGREEMENT WITH THE NAM/RGEM/HRRR ALL SHOWING THIS GENERAL TREND. THERE IS STILL A POSSIBILITY THAT THIS WILL HOLD TOGETHER LONG ENOUGH TO HAVE SOME IMPACT ON OUR CWA...WITH THE SAINT LAWRENCE RIVER AND NORTH COUNTRY AND POSSIBLY PORTIONS OF THE NIAGARA FRONTIER THE AREAS TO WATCH. IT WILL BE TRICKY...SINCE THE LINE WILL PROBABLY BE QUITE IMPRESSIVE JUST UPSTREAM OF THE LAKE BREEZE...WITH BOWING LINE SEGMENTS CAPABLE OF PRODUCING STRONG WINDS. THIS INITIAL LINE WILL IMPACT OUR REGION BETWEEN 700 PM AND 1000 PM. BEHIND THIS...IS A SECONDARY LINE OF THUNDERSTORMS DEVELOPING ALONG WHAT APPEARS TO BE A PRE-FRONTAL TROF WIND SHIFT BOUNDARY. 00/12Z RUNS OF THE NAM/RGEM AND RECENT RUNS OF THE HRRR CONTINUE TO SUGGEST THAT THIS AREA WILL EXPAND...AND EVENTUALLY DROP ACROSS OUR REGION DURING THE OVERNIGHT HOURS. THE LATER TIMING...AND CLOSER PROXIMITY TO THE SHORTWAVE WILL MAKE THIS FEATURE MORE LIKELY TO HOLD TOGETHER AS IT DROPS ACROSS THE LAKES AND ACROSS WESTERN NEW YORK LATE TONIGHT AND INTO SATURDAY MORNING. THIS TIMING IS CLIMATOLOGICALLY NOT FAVORABLE FOR SEVERE WEATHER...BUT GIVEN THE SIGNIFICANT AMOUNT OF NIGHTTIME INSTABILITY...AND STILL A FAIR AMOUNT OF SHEAR...IT WILL BEAR A RADAR WATCH IF IT DOES INDEED DEVELOP AS FORECAST. IN ADDITION TO THE SEVERE WEATHER THREAT...THERE WILL ALSO BE A RISK FOR LOCALLY HEAVY DOWNPOURS. PRECIPITABLE WATER VALUES WILL BE 1.75 TO 2.00 INCHES...AND WHILE STORMS WILL LIKELY BE MOVING...LARGE AREAS OF CONVECTION OR BRIEF TRAINING COULD QUICKLY ADD UP AND LEAD TO LOCALIZED FLOODING. ON SATURDAY...EXPECT MOST OF THE SHOWERS AND THUNDERSTORM ACTIVITY TO SLIDE TO THE SOUTH AND EAST OF THE AREA LATE MORNING AND INTO THE AFTERNOON HOURS. THE ACTUAL FRONTAL BOUNDARY WILL NOT CROSS UNTIL LATER IN THE DAY...BUT MUCH DRIER AIR WILL MOVE IN BEHIND THE PRE-FRONTAL TROF WITH ONLY MARGINAL CHANCE FOR ANY SHOWERS OR THUNDERSTORMS ALONG THE FRONT ITSELF WHICH WILL CROSS LATE IN THE DAY SATURDAY. WITH COOLER AIR MOVING IN AND LINGERING PRECIPITATION...TEMPERATURES WILL BE NOTABLY COOLER ON SATURDAY...WITH HIGHS MAINLY IN THE LOWER 80S. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... THE MAIN STORY THIS WEEKEND WILL BE THE PASSAGE OF A COLD FRONT THAT WILL BREAK THE HEAT WAVE THE REGION HAS BEEN EXPERIENCING OF LATE AND USHER IN A RETURN TO MUCH MORE SEASONABLE TEMPERATURES. AS WE OPEN THE WEEKEND SATURDAY MORNING HOWEVER...SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE PRE-FRONTAL TROUGH WILL STILL LIKELY BE CROSSING THE FORECAST AREA. THIS INITIAL BATCH OF CONVECTIVE ACTIVITY SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE MORNING HOURS WITH THE PASSAGE OF THE TROUGH...HOWEVER A SECOND ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN DURING THE AFTERNOON/EARLY EVENING HOURS ACCOMPANYING THE PASSAGE OF THE ACTUAL COLD FRONT. WITH THE LOW LEVEL JET WELL TO OUR EAST AND MODEL CAPES ONLY IN THE 500-1000 J/KG RANGE...ANY SHOWERS AND THUNDERSTORMS THAT DO OCCUR SHOULD REMAIN RELATIVELY BENIGN. THE COMBINATION OF CLOUD COVER AND THE GRADUAL FILTERING OF COOLER AIR INTO THE REGION BEHIND THE PRE-FRONTAL TROUGH MEANS THAT MOST AREAS SHOULD ONLY TOP OUT IN THE LOWER 80S...THOUGH AREAS SOUTHEAST OF LAKE ONTARIO COULD STILL SEE HIGHS IN THE MID 80S THANKS TO DOWNSLOPING SOUTHWESTERLY FLOW AHEAD OF THE COLD FRONT. THE COLD FRONT WILL CROSS WESTERN/NORTH CENTRAL NEW YORK SATURDAY EVENING BRINGING AN END TO ANY LINGERING PRECIPITATION AS MUCH COOLER AND DRIER AIR ADVECTS INTO THE REGION. WITH THE MUCH ANTICIPATED ARRIVAL OF THIS AIRMASS LOOK FOR TEMPERATURES TO DIP INTO THE MID 50S ACROSS THE NORTH COUNTRY AND SOUTHERN TIER WHILE THE LAKE PLAINS AND FINGER LAKES WILL COOL INTO THE LOWER 60S. THE COOLING TEMPERATURES COMBINED WITH ANY LINGERING MOISTURE FROM FRIDAY NIGHT/SATURDAY/S RAINFALL COULD LEAD TO PATCHY FOG ACROSS THE SOUTHERN TIER. DRY AND MILD WEATHER WILL PREVAIL ON SUNDAY AND SUNDAY NIGHT AS HIGH PRESSURE SETTLES OVER THE GREAT LAKES IN THE WAKE OF THE COLD FRONT. HIGHS IN THE MID TO UPPER 70S ON SUNDAY WILL PROVIDE A REFRESHING BREAK FROM THE RECENT HEAT. WHILE MOST AREAS SHOULD SEE PLENTY OF SUNSHINE...WITH 850MB TEMPERATURES COOLING TO THE +8 TO +10C RANGE AND LAKE TEMPERATURES RUNNING A TOASTY +25C...CANNOT RULE OUT THE POSSIBILITY OF SOME LAKE INDUCED CLOUD COVER CREEPING INTO WESTERN NEW YORK. ANY LAKE INDUCED CLOUD COVER SHOULD DIMINISH SUNDAY EVENING AS WINDS VEER TO TO THE EAST...HOWEVER EXPECT MID/HIGH CLOUDS TO MOVE IN FROM THE WEST LATER SUNDAY NIGHT AHEAD OF A WEAK SHORTWAVE CROSSING THE CENTRAL GREAT LAKES. && .LONG TERM /MONDAY THROUGH THURSDAY/... BY MONDAY HIGH PRESSURE WILL DRIFT OFF THE NEW ENGLAND COAST... ALLOWING SOUTHERLY RETURN FLOW TO BEGIN. MODELS CONTINUE TO BE A LITTLE MORE AGGRESSIVE IN BRINGING A PLUME OF DEEPER MOISTURE AND PERHAPS A FEW SHOWERS INTO EASTERN PA AND NY...BUT IT STILL APPEARS THIS WILL REMAIN MAINLY TO OUR EAST. HAVE CONTINUED WITH A DRY FORECAST FOR MONDAY WITH TEMPERATURES MODERATING TO VERY CLOSE TO AVERAGE. TUESDAY THROUGH THURSDAY A BROAD TROUGH WILL SLOWLY EVOLVE IN THE GREAT LAKES. NUMEROUS SHORTWAVE FEATURES WILL ROTATE THROUGH THE DEVELOPING TROUGH...BUT MODEL GUIDANCE REMAINS OUT OF PHASE WITH RESPECT TO TIMING AND AMPLITUDE OF THESE FEATURES. AT THIS POINT HAVE JUST BLANKETED THE PERIOD WITH LOW CHANCE POPS UNTIL BETTER MODEL AGREEMENT ALLOWS FOR MORE REFINED TIMING. TEMPERATURES WILL RETURN TO A LITTLE ABOVE AVERAGE AND HUMIDITY WILL INCREASE...BUT BOTH WILL REMAIN BELOW THE LEVELS OF THIS WEEK. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... FOR THE 18Z TAF CYCLE...GUSTY SW WINDS TO BE THE MAIN IMPACT FOR THIS AFTERNOON...WITH BUF/IAG/ROC/ART ALL SEEING PREVAILING GUSTS IN THE 30 TO 35 KT RANGE. WIDELY SCATTERED THUNDERSTORMS MAY BRIEFLY IMPACT JHW. AFTER THIS...A LINE OF THUNDERSTORMS WILL APPROACH FROM THE WEST 23Z. THIS AREA WILL PROBABLY WEAKEN AS IT MOVES INTO OUR REGION...BUT MAY HOLD TOGETHER LONG ENOUGH TO IMPACT IAG/ART...AND POSSIBLY BUF/ROC DURING THE EVENING HOURS. STEADIER THUNDERSTORMS ARE LIKELY LATE TONIGHT AS A LARGER AREA IS FORECAST TO DROP ACROSS THE REGION. ALL THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND WIND SHIFTS...WITH HEAVY RAIN LOWERING VSBY TO 1SM. STORMS WILL DROP FROM N-S LATE TONIGHT AND INTO SATURDAY MORNING...WITH CONDITIONS IMPROVING TO VFR. OUTLOOK... SATURDAY NIGHT THROUGH MONDAY MORNING...VFR. MONDAY AFTERNOON THROUGH WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS. && .MARINE... AN INCREASING PRESSURE GRADIENT WILL BRING GUSTY SOUTHWEST WINDS TODAY TO THE LAKES...ESPECIALLY LAKE ERIE AND ACROSS BOTH RIVERS. WINDS AND WAVES WILL BUILD TO SMALL CRAFT ADVISORY LEVELS THROUGH THE DAY TODAY...THEN LINGER AT THESE LEVELS THROUGH TONIGHT/EARLY SATURDAY. WILL CONTINUE WITH SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS OF LAKES ERIE AND ONTARIO...AS WELL AS THE NIAGARA RIVER AND SAINT LAWRENCE RIVER. A GREATER AND MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES WILL ARRIVE FOR TONIGHT AS A COLD FRONT MAKES ITS WAY ACROSS THE LOWER LAKES...BRINGING THE POTENTIAL FOR STRONGER TO POTENTIALLY SEVERE STORMS WITH LOCALLY STRONG WINDS AND HIGHER WAVES. CONDITIONS WILL RETURN TO BELOW SCA LATER ON SATURDAY AND REMAIN BELOW SCA THROUGH THE REMAINDER OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. && .CLIMATE... HOT AND HUMID WEATHER WILL CONTINUE THROUGH TODAY AND TEMPERATURES WILL APPROACH RECORD HIGHS THIS AFTERNOON...THOUGH THE ONLY SITE THAT IS EXPECTED TO AT LEAST TIE IT/S RECORD HIGH IS ROCHESTER. HOWEVER...WITH READINGS IN THE UPPER 70S THIS FRIDAY MORNING...RECORD WARM LOWS SHOULD BE BROKEN AT ALL THREE LOCATIONS BELOW. HERE ARE THE RECORDS FOR THE REMAINDER OF THE WORK WEEK. BUFFALO.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 75 ROCHESTER.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 95 75 WATERTOWN.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 72 HERE ARE THE MONTHLY AND ALL TIME RECORD LOW MINIMUMS... BUFFALO.. JULY.. 78 1897 ALL TIME.. 79 2006 ROCHESTER.. JULY (ALL TIME)..81 1936 AND 1940 WATERTOWN.. JULY (ALL TIME).. 79 2011 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001>006-011- 013-014. WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001-002-010- 011-019-085. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ030-042-043. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LOZ044- 045. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL SHORT TERM...WOOD LONG TERM...HITCHCOCK AVIATION...APFFEL MARINE...APFFEL/THOMAS CLIMATE...HITCHCOCK/WOOD/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1114 AM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY...WITH PLENTY OF SUNSHINE AND MAINLY RAIN FREE CONDITIONS TODAY. THERE WILL BE JUST AN ISOLATED STORM WELL INLAND FROM THE LAKES THIS AFTERNOON. THERE WILL ALSO BE A GUSTY SOUTHWESTERLY WIND TODAY AHEAD OF A COLD FRONT...WITH THE COLD FRONT BRINGING SOME SHOWERS AND THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY ACROSS THE REGION. COMFORTABLE CONDITIONS WILL FINALLY RETURN BEHIND THE FRONT FOR SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... ANOTHER VERY WARM AND MUGGY START TO THE DAY TODAY WITH A FADING AREA OF HIGH PRESSURE STILL ANCHORED NEAR THE SOUTHEAST COASTLINE. AN AREA OF LOW PRESSURE NEAR JAMES BAY THIS MORNING IS PUSHING EASTWARD...WITH SUPPORT FROM AN UPPER LEVEL SHORTWAVE SEEN ON WATER VAPOR IMAGERY JUST TO THE SOUTHWEST OF HUDSON BAY. A COLD FRONT FROM THIS AREA OF LOW PRESSURE IS SLICING ACROSS THE NORTHERN PLAINS AND UPPER GREAT LAKES THIS EARLY MORNING. AS OF 1000 AM...RADAR SHOWS A LONE SHOWER HAS DEVELOPED ACROSS THE NORTHEAST SHORELINE OF LAKE ERIE. WHILE THIS STORM SHOULD STRUGGLE TO MAKE IT ACROSS THE DEVELOPING LAKE SHADOW...EXPANDING CUMULUS CLOUDS WITH SOME HINT OF QPF FROM THE HRRR AND 00Z RGEM SUGGEST THERE MAY BE A FEW SHOWERS OR THUNDERSTORMS DEVELOPING ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER LATE MORNING/EARLY AFTERNOON. AS WINDS ALOFT INCREASE...THIS ACTIVITY SHOULD GET PUSHED FURTHER EAST OF THE LAKES...AS SHADOWING BECOMES MORE PRONOUNCED. OTHERWISE...THE TWO PRIMARY CONCERNS FOR TODAY WILL BE THE HEAT AND GUSTY WINDS...FOLLOWED BY THE PROSPECTS FOR STRONG THUNDERSTORMS THIS EVENING AND OVERNIGHT. TODAY A TIGHTENING PRESSURE GRADIENT BETWEEN THE AREA OF LOW PRESSURE OVER ONTARIO CANADA AND THE SURFACE HIGH PRESSURE OVER THE SOUTHEAST WILL BRING GUSTY SOUTHWEST WINDS ACROSS THE CWA. A LOW LEVEL JET OF 40 TO 45 KNOTS ABOUT 2 TO 3K FEET ABOVE THE SURFACE WILL PASS OVER THE REGION. WITH PLENTY OF SUNSHINE TODAY INCREASING MIXING HEIGHTS...UPWARD INTO THIS LLJ GUSTY WINDS WILL BE BROUGHT DOWN TO THE SURFACE. THE STRONGEST GUSTS WILL BE FOUND ALONG THE LAKE ERIE SHORELINE AND INLAND ACROSS THE NIAGARA FRONTIER WHERE FUNNELING UP LAKE ERIE WILL BRING GUSTS IN THE 40 TO 45 MPH RANGE. WHILE THERE WILL JUST BE ISOLATED GUSTS ABOVE 45 MPH...HAVE DECIDED TO ISSUE A WIND ADVISORY MORE SO FOR IMPACT OF THESE SUMMERTIME WINDS SPEEDS...WITH TREES FULLY FOLIATED. THE OTHER ISSUE FOR TODAY WILL BE THE HEAT. TEMPERATURES ALOFT WILL RISE ABOUT A DEGREE FROM YESTERDAY WITH 19 TO 20C AIR ABOVE THE EASTERN GREAT LAKES...AND A SOUTHWESTERLY DOWNSLOPE FLOW WILL BRING PERHAPS THE HOTTEST DAY OF THE YEAR FOR LOWER ELEVATIONS. TEMPERATURES WILL RISE TOWARDS 90 DEGREES THROUGH THE REGION...WITH MID 90S LIKELY ACROSS THE NORTHERN NIAGARA FRONTIER AND TOWARDS THE GENESEE VALLEY/FINGER LAKES REGION AND THE BLACK RIVER VALLEY. A DOWNSLOPE FLOW ACROSS THE LOWER ELEVATIONS MAY BRING SPOTS TO NEAR RECORD HEAT FOR THE DAY. WITH A MOIST AIRMASS REMAINING...DEWPOINTS INTO THE LOWER 70S APPARENT TEMPERATURES WILL RISE ABOVE 100F FOR MUCH OF OUR CWA. HAVE ALSO ISSUED A HEAT ADVISORY FOR NIAGARA COUNTY...EASTWARD ACROSS ORLEANS/GENESEE AND INTO THE GENESEE VALLEY AND FINGER LAKES REGION. OUTSIDE THIS AREA IT WILL STILL BE HOT WITH APPARENT TEMPERATURES INTO THE 90S. STRONG SOUTHWEST FLOW WILL BRING THE LAKE ERIE BREEZE WELL INLAND TODAY AND SHADOW AREAS DOWNWIND OF BOTH GREAT LAKES. THE LACK OF UPPER LEVEL SUPPORT FOR THUNDERSTORMS WILL AGAIN BRING THE PRIMARY FOCUS FOR LIFT UPON THESE LAKE BREEZE BOUNDARIES...WITH SOME ADDITIONAL LIFT FROM THE APPROACHING LLJ AND THE CONVERGENCE ALONG THIS JET. A FEW THUNDERSTORMS ARE POSSIBLE ACROSS WELL INLAND AREAS...AND ACROSS THE EASTERN LAKE ONTARIO REGION THIS AFTERNOON. TONIGHT THE CONCERN WILL SHIFT FROM THE HEAT AND WINDS TO THE THUNDERSTORMS THAT WILL BE FORMING ALONG A PRE FRONTAL TROUGH WELL AHEAD OF THE MAIN COLD FRONT. THE TIMING OF THIS SURFACE TROUGH AND SHOWER AND THUNDERSTORM ACTIVITY BRINGS IT INTO OUR REGION AFTER THE PEAK DAYTIME HEATING. STILL SBCAPES OF 1000 TO 2000 J/KG WILL REMAIN IN THIS VERY WARM AIRMASS...AND INCREASING MID LEVEL MOISTURE WILL FUEL SHOWERS AND THUNDERSTORMS DROPPING SOUTHEASTWARD ACROSS THE CWA. ALOFT DYNAMICS BECOME A LITTLE MORE FAVORABLE FOR WIDESPREAD SHOWERS AND THUNDERSTORMS TONIGHT WITH A 120 KNOT 250 HPA JET CENTERED OVER QUEBEC WITH OUR EASTERN GREAT LAKES REGION WITHIN THE RIGHT ENTRANCE REGION. THERE WILL ALSO BE FALLING HEIGHTS ALOFT AHEAD OF THE SHORTWAVE THAT WILL SLIDE SOUTHWARD DOWN THE WEST SIDE OF HUDSON BAY TODAY AND TOWARDS THE UPPER GREAT LAKES TONIGHT. A STILL STRONG LLJ OF 35 TO 40 KNOTS WILL REMAIN ACROSS THE CWA...AND THIS JET COMBINED WITH DOWNDRAFTS FROM THUNDERSTORMS WILL POSE THE PROSPECTS FOR GUSTY TO DAMAGING WINDS WITH THE OVERNIGHT CONVECTION. WILL CONTINUE TO MENTION GUSTY WINDS IN THE GRIDS ALONG WITH THE HEAVY RAINFALL AS PWATS CLIMB TOWARDS 1.75 TO 2.00 INCHES. WHILE THUNDERSTORMS ARE LIKELY ACROSS MUCH OF THE CWA TONIGHT...WILL PLACE JUST A HIGH CHANCE ACROSS THE FAR SOUTHERN GENESEE VALLEY WHICH WILL REMAIN SOUTH OF THE BEST UPPER LEVEL DYNAMICS...AND EASTWARD OF THE SURFACE TROUGH. THE COLD FRONT WILL ONLY REACH FROM ABOUT QUEBEC...TO DETROIT TO CENTRAL ILLINOIS BY 12Z SATURDAY. THIS WILL LEAVE OUR REGION STILL WITHIN THE WARM SECTOR WITH OVERNIGHT LOWS REMAINING IN THE 70S. WITH WARM TEMPERATURES THROUGH 1 AM EDT...SOME OF OUR CLIMATE SITES MAY SET NOT ONLY DAILY...BUT NEAR MONTHLY RECORD HIGH MINIMUMS. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... THE MAIN STORY THIS WEEKEND WILL BE THE PASSAGE OF A COLD FRONT THAT WILL BREAK THE HEAT WAVE THE REGION HAS BEEN EXPERIENCING OF LATE AND USHER IN A RETURN TO MUCH MORE SEASONABLE TEMPERATURES. AS WE OPEN THE WEEKEND SATURDAY MORNING HOWEVER...SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE PRE-FRONTAL TROUGH WILL STILL LIKELY BE CROSSING THE FORECAST AREA. THIS INITIAL BATCH OF CONVECTIVE ACTIVITY SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE MORNING HOURS WITH THE PASSAGE OF THE TROUGH...HOWEVER A SECOND ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN DURING THE AFTERNOON/EARLY EVENING HOURS ACCOMPANYING THE PASSAGE OF THE ACTUAL COLD FRONT. WITH THE LOW LEVEL JET WELL TO OUR EAST AND MODEL CAPES ONLY IN THE 500-1000 J/KG RANGE...ANY SHOWERS AND THUNDERSTORMS THAT DO OCCUR SHOULD REMAIN RELATIVELY BENIGN. THE COMBINATION OF CLOUD COVER AND THE GRADUAL FILTERING OF COOLER AIR INTO THE REGION BEHIND THE PRE-FRONTAL TROUGH MEANS THAT MOST AREAS SHOULD ONLY TOP OUT IN THE LOWER 80S...THOUGH AREAS SOUTHEAST OF LAKE ONTARIO COULD STILL SEE HIGHS IN THE MID 80S THANKS TO DOWNSLOPING SOUTHWESTERLY FLOW AHEAD OF THE COLD FRONT. THE COLD FRONT WILL CROSS WESTERN/NORTH CENTRAL NEW YORK SATURDAY EVENING BRINGING AN END TO ANY LINGERING PRECIPITATION AS MUCH COOLER AND DRIER AIR ADVECTS INTO THE REGION. WITH THE MUCH ANTICIPATED ARRIVAL OF THIS AIRMASS LOOK FOR TEMPERATURES TO DIP INTO THE MID 50S ACROSS THE NORTH COUNTRY AND SOUTHERN TIER WHILE THE LAKE PLAINS AND FINGER LAKES WILL COOL INTO THE LOWER 60S. THE COOLING TEMPERATURES COMBINED WITH ANY LINGERING MOISTURE FROM FRIDAY NIGHT/SATURDAY/S RAINFALL COULD LEAD TO PATCHY FOG ACROSS THE SOUTHERN TIER. DRY AND MILD WEATHER WILL PREVAIL ON SUNDAY AND SUNDAY NIGHT AS HIGH PRESSURE SETTLES OVER THE GREAT LAKES IN THE WAKE OF THE COLD FRONT. HIGHS IN THE MID TO UPPER 70S ON SUNDAY WILL PROVIDE A REFRESHING BREAK FROM THE RECENT HEAT. WHILE MOST AREAS SHOULD SEE PLENTY OF SUNSHINE...WITH 850MB TEMPERATURES COOLING TO THE +8 TO +10C RANGE AND LAKE TEMPERATURES RUNNING A TOASTY +25C...CANNOT RULE OUT THE POSSIBILITY OF SOME LAKE INDUCED CLOUD COVER CREEPING INTO WESTERN NEW YORK. ANY LAKE INDUCED CLOUD COVER SHOULD DIMINISH SUNDAY EVENING AS WINDS VEER TO TO THE EAST...HOWEVER EXPECT MID/HIGH CLOUDS TO MOVE IN FROM THE WEST LATER SUNDAY NIGHT AHEAD OF A WEAK SHORTWAVE CROSSING THE CENTRAL GREAT LAKES. && .LONG TERM /MONDAY THROUGH THURSDAY/... BY MONDAY HIGH PRESSURE WILL DRIFT OFF THE NEW ENGLAND COAST... ALLOWING SOUTHERLY RETURN FLOW TO BEGIN. MODELS CONTINUE TO BE A LITTLE MORE AGGRESSIVE IN BRINGING A PLUME OF DEEPER MOISTURE AND PERHAPS A FEW SHOWERS INTO EASTERN PA AND NY...BUT IT STILL APPEARS THIS WILL REMAIN MAINLY TO OUR EAST. HAVE CONTINUED WITH A DRY FORECAST FOR MONDAY WITH TEMPERATURES MODERATING TO VERY CLOSE TO AVERAGE. TUESDAY THROUGH THURSDAY A BROAD TROUGH WILL SLOWLY EVOLVE IN THE GREAT LAKES. NUMEROUS SHORTWAVE FEATURES WILL ROTATE THROUGH THE DEVELOPING TROUGH...BUT MODEL GUIDANCE REMAINS OUT OF PHASE WITH RESPECT TO TIMING AND AMPLITUDE OF THESE FEATURES. AT THIS POINT HAVE JUST BLANKETED THE PERIOD WITH LOW CHANCE POPS UNTIL BETTER MODEL AGREEMENT ALLOWS FOR MORE REFINED TIMING. TEMPERATURES WILL RETURN TO A LITTLE ABOVE AVERAGE AND HUMIDITY WILL INCREASE...BUT BOTH WILL REMAIN BELOW THE LEVELS OF THIS WEEK. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... VFR FLIGHT CONDITIONS WERE IN PLACE AT 15Z ACROSS THE REGION...WITH SOME BKN CIGS AROUND 3K FEET ACROSS THE SOUTHERN TIER NEAR JHW. THE PRESSURE GRADIENT WILL INCREASE TODAY IN ADVANCE OF AN APPROACHING COLD FRONT SAGGING SOUTHWARD ACROSS ONTARIO PROVINCE... WHICH WILL RESULT IN RATHER BREEZY TO WINDY CONDITIONS DEVELOPING ACROSS THE AREA DURING THE MORNING...THEN CONTINUING THROUGH THE AFTERNOON. EXPECT SOUTHWESTERLY SURFACE WINDS TO INCREASE TO 15-25 KTS WITH GUSTS TO AS HIGH AS 35-40 KTS BY EARLY AFTERNOON...WITH THE STRONGEST WINDS MOST LIKELY DOWNWIND OF LAKE ERIE FROM KBUF/KIAG OVER TO KROC. WITH THE DEVELOPING STRONGER SOUTHWESTERLY FLOW...LAKE SHADOWS WILL QUICKLY DEVELOP AND SPREAD ACROSS MUCH OF THE AREA THIS AFTERNOON... THEREBY LIMITING ANY POTENTIAL FOR CONVECTION TO FAR SOUTHERN PORTIONS OF THE SOUTHERN TIER/FINGER LAKES AND INTERIOR PORTIONS OF THE NORTH COUNTRY FOR THE VAST MAJORITY OF THE DAY. THROUGH THE EVENING HOURS CONVECTION WILL BEGIN TO EDGE INTO WNY AS WELL AS THE NORTH COUNTRY. EXPECT CONDITIONS TO DROP TO MVFR OVERNIGHT AS THE RAIN SHOWERS PRESS SOUTHEASTWARD ACROSS THE EASTERN GREAT LAKES REGION. WITH INSTABILITY REMAINING THERE WILL ALSO LIKELY BE THUNDERSTORMS ACCOMPANYING THE PRECIPITATION. RAIN SHOWERS WITH THUNDERSTORMS WILL THEN CONTINUE TO FALL THROUGH THE END OF THE TAF CYCLE. ANY OF THESE STORMS COULD BEING BRIEF PERIODS OF IFR FLIGHT CONDITIONS. OUTLOOK... SATURDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS IS LIKELY WITH ASSOCIATED IFR/MVFR...WITH MAINLY VFR CONDITIONS OTHERWISE. SUNDAY AND MONDAY...VFR. TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS. && .MARINE... AN INCREASING PRESSURE GRADIENT WILL BRING GUSTY SOUTHWEST WINDS TODAY TO THE LAKES...ESPECIALLY LAKE ERIE AND ACROSS BOTH RIVERS. WINDS AND WAVES WILL BUILD TO SMALL CRAFT ADVISORY LEVELS THROUGH THE DAY TODAY...THEN LINGER AT THESE LEVELS THROUGH TONIGHT/EARLY SATURDAY. WILL CONTINUE WITH SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS OF LAKES ERIE AND ONTARIO...AS WELL AS THE NIAGARA RIVER AND SAINT LAWRENCE RIVER. A GREATER AND MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES WILL ARRIVE FOR TONIGHT AS A COLD FRONT MAKES ITS WAY ACROSS THE LOWER LAKES...BRINGING THE POTENTIAL FOR STRONGER TO POTENTIALLY SEVERE STORMS WITH LOCALLY STRONG WINDS AND HIGHER WAVES. CONDITIONS WILL RETURN TO BELOW SCA LATER ON SATURDAY AND REMAIN BELOW SCA THROUGH THE REMAINDER OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. && .CLIMATE... HOT AND HUMID WEATHER WILL CONTINUE THROUGH TODAY AND TEMPERATURES WILL APPROACH RECORD HIGHS THIS AFTERNOON...THOUGH THE ONLY SITE THAT IS EXPECTED TO AT LEAST TIE IT/S RECORD HIGH IS ROCHESTER. HOWEVER...WITH READINGS IN THE UPPER 70S THIS FRIDAY MORNING...RECORD WARM LOWS SHOULD BE BROKEN AT ALL THREE LOCATIONS BELOW. HERE ARE THE RECORDS FOR THE REMAINDER OF THE WORK WEEK. BUFFALO.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 75 ROCHESTER.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 95 75 WATERTOWN.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 72 HERE ARE THE MONTHLY AND ALL TIME RECORD LOW MINIMUMS... BUFFALO.. JULY.. 78 1897 ALL TIME.. 79 2006 ROCHESTER.. JULY (ALL TIME)..81 1936 AND 1940 WATERTOWN.. JULY (ALL TIME).. 79 2011 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001>006-011- 013-014. WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001-002-010- 011-019-085. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ042- 043. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LOZ044- 045. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...WOOD LONG TERM...HITCHCOCK AVIATION...APFFEL/THOMAS MARINE...APFFEL/THOMAS CLIMATE...HITCHCOCK/WOOD/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1031 AM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY...WITH PLENTY OF SUNSHINE AND MAINLY RAIN FREE CONDITIONS TODAY. THERE WILL BE JUST AN ISOLATED STORM WELL INLAND FROM THE LAKES THIS AFTERNOON. THERE WILL ALSO BE A GUSTY SOUTHWESTERLY WIND TODAY AHEAD OF A COLD FRONT...WITH THE COLD FRONT BRINGING SOME SHOWERS AND THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY ACROSS THE REGION. COMFORTABLE CONDITIONS WILL FINALLY RETURN BEHIND THE FRONT FOR SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... ANOTHER VERY WARM AND MUGGY START TO THE DAY TODAY WITH A FADING AREA OF HIGH PRESSURE STILL ANCHORED NEAR THE SOUTHEAST COASTLINE. AN AREA OF LOW PRESSURE NEAR JAMES BAY THIS MORNING IS PUSHING EASTWARD...WITH SUPPORT FROM AN UPPER LEVEL SHORTWAVE SEEN ON WATER VAPOR IMAGERY JUST TO THE SOUTHWEST OF HUDSON BAY. A COLD FRONT FROM THIS AREA OF LOW PRESSURE IS SLICING ACROSS THE NORTHERN PLAINS AND UPPER GREAT LAKES THIS EARLY MORNING. AS OF 1000 AM...RADAR SHOWS A LONE SHOWER HAS DEVELOPED ACROSS THE NORTHEAST SHORELINE OF LAKE ERIE. WHILE THIS STORM SHOULD STRUGGLE TO MAKE IT ACROSS THE DEVELOPING LAKE SHADOW...EXPANDING CUMULUS CLOUDS WITH SOME HINT OF QPF FROM THE HRRR AND 00Z RGEM SUGGEST THERE MAY BE A FEW SHOWERS OR THUNDERSTORMS DEVELOPING ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER LATE MORNING/EARLY AFTERNOON. AS WINDS ALOFT INCREASE...THIS ACTIVITY SHOULD GET PUSHED FURTHER EAST OF THE LAKES...AS SHADOWING BECOMES MORE PRONOUNCED. OTHERWISE...THE TWO PRIMARY CONCERNS FOR TODAY WILL BE THE HEAT AND GUSTY WINDS...FOLLOWED BY THE PROSPECTS FOR STRONG THUNDERSTORMS THIS EVENING AND OVERNIGHT. TODAY A TIGHTENING PRESSURE GRADIENT BETWEEN THE AREA OF LOW PRESSURE OVER ONTARIO CANADA AND THE SURFACE HIGH PRESSURE OVER THE SOUTHEAST WILL BRING GUSTY SOUTHWEST WINDS ACROSS THE CWA. A LOW LEVEL JET OF 40 TO 45 KNOTS ABOUT 2 TO 3K FEET ABOVE THE SURFACE WILL PASS OVER THE REGION. WITH PLENTY OF SUNSHINE TODAY INCREASING MIXING HEIGHTS...UPWARD INTO THIS LLJ GUSTY WINDS WILL BE BROUGHT DOWN TO THE SURFACE. THE STRONGEST GUSTS WILL BE FOUND ALONG THE LAKE ERIE SHORELINE AND INLAND ACROSS THE NIAGARA FRONTIER WHERE FUNNELING UP LAKE ERIE WILL BRING GUSTS IN THE 40 TO 45 MPH RANGE. WHILE THERE WILL JUST BE ISOLATED GUSTS ABOVE 45 MPH...HAVE DECIDED TO ISSUE A WIND ADVISORY MORE SO FOR IMPACT OF THESE SUMMERTIME WINDS SPEEDS...WITH TREES FULLY FOLIATED. THE OTHER ISSUE FOR TODAY WILL BE THE HEAT. TEMPERATURES ALOFT WILL RISE ABOUT A DEGREE FROM YESTERDAY WITH 19 TO 20C AIR ABOVE THE EASTERN GREAT LAKES...AND A SOUTHWESTERLY DOWNSLOPE FLOW WILL BRING PERHAPS THE HOTTEST DAY OF THE YEAR FOR LOWER ELEVATIONS. TEMPERATURES WILL RISE TOWARDS 90 DEGREES THROUGH THE REGION...WITH MID 90S LIKELY ACROSS THE NORTHERN NIAGARA FRONTIER AND TOWARDS THE GENESEE VALLEY/FINGER LAKES REGION AND THE BLACK RIVER VALLEY. A DOWNSLOPE FLOW ACROSS THE LOWER ELEVATIONS MAY BRING SPOTS TO NEAR RECORD HEAT FOR THE DAY. WITH A MOIST AIRMASS REMAINING...DEWPOINTS INTO THE LOWER 70S APPARENT TEMPERATURES WILL RISE ABOVE 100F FOR MUCH OF OUR CWA. HAVE ALSO ISSUED A HEAT ADVISORY FOR NIAGARA COUNTY...EASTWARD ACROSS ORLEANS/GENESEE AND INTO THE GENESEE VALLEY AND FINGER LAKES REGION. OUTSIDE THIS AREA IT WILL STILL BE HOT WITH APPARENT TEMPERATURES INTO THE 90S. STRONG SOUTHWEST FLOW WILL BRING THE LAKE ERIE BREEZE WELL INLAND TODAY AND SHADOW AREAS DOWNWIND OF BOTH GREAT LAKES. THE LACK OF UPPER LEVEL SUPPORT FOR THUNDERSTORMS WILL AGAIN BRING THE PRIMARY FOCUS FOR LIFT UPON THESE LAKE BREEZE BOUNDARIES...WITH SOME ADDITIONAL LIFT FROM THE APPROACHING LLJ AND THE CONVERGENCE ALONG THIS JET. A FEW THUNDERSTORMS ARE POSSIBLE ACROSS WELL INLAND AREAS...AND ACROSS THE EASTERN LAKE ONTARIO REGION THIS AFTERNOON. TONIGHT THE CONCERN WILL SHIFT FROM THE HEAT AND WINDS TO THE THUNDERSTORMS THAT WILL BE FORMING ALONG A PRE FRONTAL TROUGH WELL AHEAD OF THE MAIN COLD FRONT. THE TIMING OF THIS SURFACE TROUGH AND SHOWER AND THUNDERSTORM ACTIVITY BRINGS IT INTO OUR REGION AFTER THE PEAK DAYTIME HEATING. STILL SBCAPES OF 1000 TO 2000 J/KG WILL REMAIN IN THIS VERY WARM AIRMASS...AND INCREASING MID LEVEL MOISTURE WILL FUEL SHOWERS AND THUNDERSTORMS DROPPING SOUTHEASTWARD ACROSS THE CWA. ALOFT DYNAMICS BECOME A LITTLE MORE FAVORABLE FOR WIDESPREAD SHOWERS AND THUNDERSTORMS TONIGHT WITH A 120 KNOT 250 HPA JET CENTERED OVER QUEBEC WITH OUR EASTERN GREAT LAKES REGION WITHIN THE RIGHT ENTRANCE REGION. THERE WILL ALSO BE FALLING HEIGHTS ALOFT AHEAD OF THE SHORTWAVE THAT WILL SLIDE SOUTHWARD DOWN THE WEST SIDE OF HUDSON BAY TODAY AND TOWARDS THE UPPER GREAT LAKES TONIGHT. A STILL STRONG LLJ OF 35 TO 40 KNOTS WILL REMAIN ACROSS THE CWA...AND THIS JET COMBINED WITH DOWNDRAFTS FROM THUNDERSTORMS WILL POSE THE PROSPECTS FOR GUSTY TO DAMAGING WINDS WITH THE OVERNIGHT CONVECTION. WILL CONTINUE TO MENTION GUSTY WINDS IN THE GRIDS ALONG WITH THE HEAVY RAINFALL AS PWATS CLIMB TOWARDS 1.75 TO 2.00 INCHES. WHILE THUNDERSTORMS ARE LIKELY ACROSS MUCH OF THE CWA TONIGHT...WILL PLACE JUST A HIGH CHANCE ACROSS THE FAR SOUTHERN GENESEE VALLEY WHICH WILL REMAIN SOUTH OF THE BEST UPPER LEVEL DYNAMICS...AND EASTWARD OF THE SURFACE TROUGH. THE COLD FRONT WILL ONLY REACH FROM ABOUT QUEBEC...TO DETROIT TO CENTRAL ILLINOIS BY 12Z SATURDAY. THIS WILL LEAVE OUR REGION STILL WITHIN THE WARM SECTOR WITH OVERNIGHT LOWS REMAINING IN THE 70S. WITH WARM TEMPERATURES THROUGH 1 AM EDT...SOME OF OUR CLIMATE SITES MAY SET NOT ONLY DAILY...BUT NEAR MONTHLY RECORD HIGH MINIMUMS. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... THE MAIN STORY THIS WEEKEND WILL BE THE PASSAGE OF A COLD FRONT THAT WILL BREAK THE HEAT WAVE THE REGION HAS BEEN EXPERIENCING OF LATE AND USHER IN A RETURN TO MUCH MORE SEASONABLE TEMPERATURES. AS WE OPEN THE WEEKEND SATURDAY MORNING HOWEVER...SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE PRE-FRONTAL TROUGH WILL STILL LIKELY BE CROSSING THE FORECAST AREA. THIS INITIAL BATCH OF CONVECTIVE ACTIVITY SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE MORNING HOURS WITH THE PASSAGE OF THE TROUGH...HOWEVER A SECOND ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN DURING THE AFTERNOON/EARLY EVENING HOURS ACCOMPANYING THE PASSAGE OF THE ACTUAL COLD FRONT. WITH THE LOW LEVEL JET WELL TO OUR EAST AND MODEL CAPES ONLY IN THE 500-1000 J/KG RANGE...ANY SHOWERS AND THUNDERSTORMS THAT DO OCCUR SHOULD REMAIN RELATIVELY BENIGN. THE COMBINATION OF CLOUD COVER AND THE GRADUAL FILTERING OF COOLER AIR INTO THE REGION BEHIND THE PRE-FRONTAL TROUGH MEANS THAT MOST AREAS SHOULD ONLY TOP OUT IN THE LOWER 80S...THOUGH AREAS SOUTHEAST OF LAKE ONTARIO COULD STILL SEE HIGHS IN THE MID 80S THANKS TO DOWNSLOPING SOUTHWESTERLY FLOW AHEAD OF THE COLD FRONT. THE COLD FRONT WILL CROSS WESTERN/NORTH CENTRAL NEW YORK SATURDAY EVENING BRINGING AN END TO ANY LINGERING PRECIPITATION AS MUCH COOLER AND DRIER AIR ADVECTS INTO THE REGION. WITH THE MUCH ANTICIPATED ARRIVAL OF THIS AIRMASS LOOK FOR TEMPERATURES TO DIP INTO THE MID 50S ACROSS THE NORTH COUNTRY AND SOUTHERN TIER WHILE THE LAKE PLAINS AND FINGER LAKES WILL COOL INTO THE LOWER 60S. THE COOLING TEMPERATURES COMBINED WITH ANY LINGERING MOISTURE FROM FRIDAY NIGHT/SATURDAY/S RAINFALL COULD LEAD TO PATCHY FOG ACROSS THE SOUTHERN TIER. DRY AND MILD WEATHER WILL PREVAIL ON SUNDAY AND SUNDAY NIGHT AS HIGH PRESSURE SETTLES OVER THE GREAT LAKES IN THE WAKE OF THE COLD FRONT. HIGHS IN THE MID TO UPPER 70S ON SUNDAY WILL PROVIDE A REFRESHING BREAK FROM THE RECENT HEAT. WHILE MOST AREAS SHOULD SEE PLENTY OF SUNSHINE...WITH 850MB TEMPERATURES COOLING TO THE +8 TO +10C RANGE AND LAKE TEMPERATURES RUNNING A TOASTY +25C...CANNOT RULE OUT THE POSSIBILITY OF SOME LAKE INDUCED CLOUD COVER CREEPING INTO WESTERN NEW YORK. ANY LAKE INDUCED CLOUD COVER SHOULD DIMINISH SUNDAY EVENING AS WINDS VEER TO TO THE EAST...HOWEVER EXPECT MID/HIGH CLOUDS TO MOVE IN FROM THE WEST LATER SUNDAY NIGHT AHEAD OF A WEAK SHORTWAVE CROSSING THE CENTRAL GREAT LAKES. && .LONG TERM /MONDAY THROUGH THURSDAY/... BY MONDAY HIGH PRESSURE WILL DRIFT OFF THE NEW ENGLAND COAST... ALLOWING SOUTHERLY RETURN FLOW TO BEGIN. MODELS CONTINUE TO BE A LITTLE MORE AGGRESSIVE IN BRINGING A PLUME OF DEEPER MOISTURE AND PERHAPS A FEW SHOWERS INTO EASTERN PA AND NY...BUT IT STILL APPEARS THIS WILL REMAIN MAINLY TO OUR EAST. HAVE CONTINUED WITH A DRY FORECAST FOR MONDAY WITH TEMPERATURES MODERATING TO VERY CLOSE TO AVERAGE. TUESDAY THROUGH THURSDAY A BROAD TROUGH WILL SLOWLY EVOLVE IN THE GREAT LAKES. NUMEROUS SHORTWAVE FEATURES WILL ROTATE THROUGH THE DEVELOPING TROUGH...BUT MODEL GUIDANCE REMAINS OUT OF PHASE WITH RESPECT TO TIMING AND AMPLITUDE OF THESE FEATURES. AT THIS POINT HAVE JUST BLANKETED THE PERIOD WITH LOW CHANCE POPS UNTIL BETTER MODEL AGREEMENT ALLOWS FOR MORE REFINED TIMING. TEMPERATURES WILL RETURN TO A LITTLE ABOVE AVERAGE AND HUMIDITY WILL INCREASE...BUT BOTH WILL REMAIN BELOW THE LEVELS OF THIS WEEK. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... VFR FLIGHT CONDITIONS WERE FOUND AT 12Z ACROSS THE REGION...AND THESE CONDITIONS SHOULD PREVAIL THROUGH MUCH OF THE FIRST 12 TO 18 HOURS OF THIS TAF CYCLE. THE PRESSURE GRADIENT WILL INCREASE TODAY IN ADVANCE OF AN APPROACHING COLD FRONT SAGGING SOUTHWARD ACROSS ONTARIO PROVINCE... WHICH WILL RESULT IN RATHER BREEZY TO WINDY CONDITIONS DEVELOPING ACROSS THE AREA DURING THE MORNING...THEN CONTINUING THROUGH THE AFTERNOON. EXPECT SOUTHWESTERLY SURFACE WINDS TO INCREASE TO 15-25 KTS WITH GUSTS TO AS HIGH AS 35-40 KTS BY LATE MORNING/EARLY AFTERNOON...WITH THE STRONGEST WINDS MOST LIKELY DOWNWIND OF LAKE ERIE FROM KBUF/KIAG OVER TO KROC. WITH THE DEVELOPING STRONGER SOUTHWESTERLY FLOW...LAKE SHADOWS WILL QUICKLY DEVELOP AND SPREAD ACROSS MUCH OF THE AREA THIS AFTERNOON... THEREBY LIMITING ANY POTENTIAL FOR CONVECTION TO FAR SOUTHERN PORTIONS OF THE SOUTHERN TIER/FINGER LAKES AND INTERIOR PORTIONS OF THE NORTH COUNTRY FOR THE VAST MAJORITY OF THE DAY. THROUGH THE EVENING HOURS CONVECTION WILL BEGIN TO EDGE INTO WNY AS WELL AS THE NORTH COUNTRY. EXPECT CONDITIONS TO DROP TO MVFR OVERNIGHT AS THE RAIN SHOWERS PRESS SOUTHEASTWARD ACROSS THE EASTERN GREAT LAKES REGION. WITH INSTABILITY REMAINING THERE WILL ALSO LIKELY BE THUNDERSTORMS ACCOMPANYING THE PRECIPITATION. RAIN SHOWERS WITH THUNDERSTORMS WILL THEN CONTINUE TO FALL THROUGH THE END OF THE TAF CYCLE. ANY OF THESE STORMS COULD BEING BRIEF PERIODS OF IFR FLIGHT CONDITIONS. OUTLOOK... SATURDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS IS LIKELY WITH ASSOCIATED IFR/MVFR...WITH MAINLY VFR CONDITIONS OTHERWISE. SUNDAY AND MONDAY...VFR. TUESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS/THUNDERSTORMS. && .MARINE... AN INCREASING PRESSURE GRADIENT WILL BRING GUSTY SOUTHWEST WINDS TODAY TO THE LAKES...ESPECIALLY LAKE ERIE AND ACROSS BOTH RIVERS. WINDS AND WAVES WILL BUILD TO SMALL CRAFT ADVISORY LEVELS THROUGH THE DAY TODAY...THEN LINGER AT THESE LEVELS THROUGH TONIGHT/EARLY SATURDAY. WILL CONTINUE WITH SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS OF LAKES ERIE AND ONTARIO...AS WELL AS THE NIAGARA RIVER AND SAINT LAWRENCE RIVER. A GREATER AND MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES WILL ARRIVE FOR TONIGHT AS A COLD FRONT MAKES ITS WAY ACROSS THE LOWER LAKES...BRINGING THE POTENTIAL FOR STRONGER TO POTENTIALLY SEVERE STORMS WITH LOCALLY STRONG WINDS AND HIGHER WAVES. CONDITIONS WILL RETURN TO BELOW SCA LATER ON SATURDAY AND REMAIN BELOW SCA THROUGH THE REMAINDER OF THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. && .CLIMATE... HOT AND HUMID WEATHER WILL CONTINUE THROUGH TODAY AND TEMPERATURES WILL APPROACH RECORD HIGHS THIS AFTERNOON...THOUGH THE ONLY SITE THAT IS EXPECTED TO AT LEAST TIE IT/S RECORD HIGH IS ROCHESTER. HOWEVER...WITH READINGS IN THE UPPER 70S THIS FRIDAY MORNING...RECORD WARM LOWS SHOULD BE BROKEN AT ALL THREE LOCATIONS BELOW. HERE ARE THE RECORDS FOR THE REMAINDER OF THE WORK WEEK. BUFFALO.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 75 ROCHESTER.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 95 75 WATERTOWN.. DATE RECORD HIGH RECORD WARM LOW FRI 7/19 92 72 HERE ARE THE MONTHLY AND ALL TIME RECORD LOW MINIMUMS... BUFFALO.. JULY.. 78 1897 ALL TIME.. 79 2006 ROCHESTER.. JULY (ALL TIME)..81 1936 AND 1940 WATERTOWN.. JULY (ALL TIME).. 79 2011 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001>006-011- 013-014. WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ001-002-010- 011-019-085. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LOZ042- 043. SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR LOZ044- 045. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR SLZ022-024. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...WOOD LONG TERM...HITCHCOCK AVIATION...THOMAS MARINE...THOMAS CLIMATE...HITCHCOCK/WOOD/THOMAS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
150 PM EDT FRI JUL 19 2013 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL EXTEND INTO THE AREA THROUGH SATURDAY. A COLD FRONT WILL APPROACH THE CAROLINAS ON SUNDAY AND THEN STALL ACROSS THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1020 AM FRIDAY... 12Z SOUNDINGS FROM AROUND THE AREA SHOWED A MODEST CAP AROUND 700MB AT KMHX...WITH THE CAP AT THAT LEVEL MUCH WEAKER TOWARD KGSO GIVEN TEMPERATURES 2C TO 3C COOLER. THE LATEST RUC INDICATES GENERAL SUBSIDENCE OVER CENTRAL NORTH CAROLINA THIS AFTERNOON...WITH WEAK WINDS ALOFT AND THE MOST FAVORABLE ITEMS FOR ANY RELATIVELY DEEP LIFT BEING THE SURFACE TROUGH LINGERING OVER THE WESTERN PIEDMONT... COUPLED WITH A WEAK 850MB TROUGH IN THE SAME AREA AND AVAILABLE LOW-LEVEL MOISTURE. OVERALL MOISTURE SHOULD BE BEST TOWARD THE NORTHWEST PIEDMONT LATER THIS AFTERNOON WHERE HIGHER 850MB THETA-E VALUES ARE FORECAST. IT IS ALSO IN THAT LOCATION WHERE THE BETTER 1000-500MB LAPSE RATES ARE FORECAST...NEAR 6.75C/KM...AND WHERE THE BETTER INSTABILITY LIES...2000-2500J/KG VERSUS A FORECAST OF ONLY 1000-1500J/KG TOWARD THE COASTAL PLAIN. CONVECTION-ALLOWING MODELS...GIVEN THE GENERAL SUBSIDENCE...ARE MOSTLY RELUCTANT TO FORECAST MUCH PRECIPITATION IN CENTRAL NORTH CAROLINA...BUT WITHIN THE SLIGHT CHANCE RANGE...THE BETTER CHANCE SHOULD MAINLY BE ALONG AND NORTH/WEST OF INTERSTATE 85. AS NOTED PREVIOUSLY...WEAK WINDS ALOFT WILL ALLOW ANY OF THE ISOLATED STORMS TO MOVE ONLY VERY SLOWLY. 1000-850MB THICKNESSES AT 12Z AND FORECAST LATE THIS AFTERNOON ARE BASICALLY PERSISTENCE FROM THURSDAY...AND HAVE FORECAST HIGHS CLOSE TO THOSE OF THURSDAY AS A RESULT. THIS PLACES MOST LOCATIONS WITH HEAT INDICES AROUND 100...A COUPLE OF DEGREES WARMER TOWARD KIXA AND KRZZ. ANY THUNDERSTORMS SHOULD DIMINISH DIURNALLY...WITH OVERNIGHT LOWS IN THE LOWER TO MID 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 245 AM FRIDAY... THE NORTHERN STREAM TROUGH AND ASSOCIATED SFC COLD FRONT WILL REMAIN NORTH OF THE AREA...SAGGING SOUTH INTO THE SOUTHERN OHIO VALLEY AND NORTHERN MID-ATLANTIC STATES BY SUNDAY MORNING. NOT MANY DIFFERENCES BETWEEN TODAY AND SATURDAY WITH THE SAME MESOSCALE FORCING DRIVING ISOLATED TO SCATTERED DIURNAL CONVECTION SATURDAY AFTERNOON HIGHS IN THE LOWER 90S. LOWS IN THE LOWER TO MID 70S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS OF 150 PM FRIDAY... SUNDAY AND MONDAY... THE BACKDOOR COLD FRONT OVER THE OHIO VALLEY WILL BE SLOW TO EDGE SOUTH AND IS EXPECTED TO STALL NORTH OF THE AREA SUNDAY AND MONDAY AS IT ALIGNS PARALLEL TO THE FLOW ALONG THE LOW AMPLITUDE UPPER TROF. TANGIBLE DISTURBANCES IN THE LARGER FLOW REGIME ARE NOT READILY EVIDENT AT THIS TIME...BUT MOISTURE AND INSTABILITY WILL BE MORE THAN ADEQUATE FOR SUPPORT OF MAINLY DIURNAL CONVECTION. WILL CONTINUE POPS IN THE 50-60 PERCENT RANGE BOTH DAYS. SMALL HEIGHT FALLS AND REDUCED INSOLATION WILL TAKE THE EDGE OFF OUR HIGH TEMPERATURES...AND HIGHS BOTH DAYS WILL BE SLIGHTLY COOLER THAN NORMAL...IN THE 85 TO 90 RANGE. TUESDAY THROUGH FRIDAY... VERY SLOW EASTWARD TRANSLATION AND DEEPENING OF THE UPPER TROF TO OUR WEST WILL KEEP US IN AN UNSETTLED PATTERN THROUGH AT LEAST THURSDAY. THE STALLED FRONT NORTH OF THE AREA BECOMES MORE DIFFUSE WITH TIME... MEANWHILE THE PERSISTENT LEE TROF ALONG THE EASTERN SEABOARD SHARPENS IN STRENGTHENING SOUTHWEST FLOW AHEAD OF THE DEEPENING UPPER TROF. THE PROBABILITY OF PRECIP WILL REMAIN ABOVE NORMAL ACROSS THE AREA AS THE NEAR STAGNANT AIRMASS WILL REQUIRE LITTLE FORCING TO GENERATE CONVECTION...ITS THE DISTRIBUTION AND TIMING WHICH WILL REMAIN LOW CONFIDENCE. THAT SAID...WILL HAVE 40-50 POPS TUE THROUGH FRI...AGAIN FOCUSING ON MAX DIURNAL HEATING...WITH PERSISTENCE HIGHS FROM 85-90. THE UPPER TROF MAY MAKE ITS MOVE EAST ACROSS THE AREA LATE THIS WEEK...WHICH WOULD ENHANCE AS WELL AS PROVIDE ORGANIZATION FOR CONVECTION IN THE LATE THURSDAY OR FRIDAY TIME FRAME...AS WELL AS INITIATE A DRYING TREND FOR THE UPCOMING WEEKEND...WE SHALL SEE. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 1205 PM FRIDAY... VFR CONDITIONS ARE CURRENTLY BEING REPORTED ACROSS MOST OF CENTRAL NC. THIS IS EXPECTED TO REMAIN THE CASE THROUGH THE 24 HOUR TAF PERIOD...WITH THE EXCEPTION OF A FEW ISOLD TSTMS DURING THE REST OF THIS AFTERNOON AND EARLY EVENING THAT MAY BRIEFLY REDUCE FLT CONDITIONS TO MVFR. BEYOND THE 24 HOUR TAF PERIOD: OUTSIDE OF SOME EARLY MORNING FOG/STRATUS SATURDAY...VFR CONDITIONS SHOULD PREVAIL WITH ONLY ISOLATED AFTERNOON STORMS. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY AND WILL STALL ACROSS THE AREA THROUGH EARLY NEXT WEEK. THIS WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...WITH SUB VFR CONDITIONS IN HEAVY RAIN. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/DJF SHORT TERM...CBL LONG TERM...MLM AVIATION...NP/CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1205 PM EDT FRI JUL 19 2013 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL EXTEND INTO THE AREA THROUGH SATURDAY. A COLD FRONT WILL APPROACH THE CAROLINAS ON SUNDAY AND THEN STALL ACROSS THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1020 AM FRIDAY... 12Z SOUNDINGS FROM AROUND THE AREA SHOWED A MODEST CAP AROUND 700MB AT KMHX...WITH THE CAP AT THAT LEVEL MUCH WEAKER TOWARD KGSO GIVEN TEMPERATURES 2C TO 3C COOLER. THE LATEST RUC INDICATES GENERAL SUBSIDENCE OVER CENTRAL NORTH CAROLINA THIS AFTERNOON...WITH WEAK WINDS ALOFT AND THE MOST FAVORABLE ITEMS FOR ANY RELATIVELY DEEP LIFT BEING THE SURFACE TROUGH LINGERING OVER THE WESTERN PIEDMONT... COUPLED WITH A WEAK 850MB TROUGH IN THE SAME AREA AND AVAILABLE LOW-LEVEL MOISTURE. OVERALL MOISTURE SHOULD BE BEST TOWARD THE NORTHWEST PIEDMONT LATER THIS AFTERNOON WHERE HIGHER 850MB THETA-E VALUES ARE FORECAST. IT IS ALSO IN THAT LOCATION WHERE THE BETTER 1000-500MB LAPSE RATES ARE FORECAST...NEAR 6.75C/KM...AND WHERE THE BETTER INSTABILITY LIES...2000-2500J/KG VERSUS A FORECAST OF ONLY 1000-1500J/KG TOWARD THE COASTAL PLAIN. CONVECTION-ALLOWING MODELS...GIVEN THE GENERAL SUBSIDENCE...ARE MOSTLY RELUCTANT TO FORECAST MUCH PRECIPITATION IN CENTRAL NORTH CAROLINA...BUT WITHIN THE SLIGHT CHANCE RANGE...THE BETTER CHANCE SHOULD MAINLY BE ALONG AND NORTH/WEST OF INTERSTATE 85. AS NOTED PREVIOUSLY...WEAK WINDS ALOFT WILL ALLOW ANY OF THE ISOLATED STORMS TO MOVE ONLY VERY SLOWLY. 1000-850MB THICKNESSES AT 12Z AND FORECAST LATE THIS AFTERNOON ARE BASICALLY PERSISTENCE FROM THURSDAY...AND HAVE FORECAST HIGHS CLOSE TO THOSE OF THURSDAY AS A RESULT. THIS PLACES MOST LOCATIONS WITH HEAT INDICES AROUND 100...A COUPLE OF DEGREES WARMER TOWARD KIXA AND KRZZ. ANY THUNDERSTORMS SHOULD DIMINISH DIURNALLY...WITH OVERNIGHT LOWS IN THE LOWER TO MID 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 245 AM FRIDAY... THE NORTHERN STREAM TROUGH AND ASSOCIATED SFC COLD FRONT WILL REMAIN NORTH OF THE AREA...SAGGING SOUTH INTO THE SOUTHERN OHIO VALLEY AND NORTHERN MID-ATLANTIC STATES BY SUNDAY MORNING. NOT MANY DIFFERENCES BETWEEN TODAY AND SATURDAY WITH THE SAME MESOSCALE FORCING DRIVING ISOLATED TO SCATTERED DIURNAL CONVECTION SATURDAY AFTERNOON HIGHS IN THE LOWER 90S. LOWS IN THE LOWER TO MID 70S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 230 AM FRIDAY... SUNDAY THROUGH THURSDAY: THIS PERIOD WILL BE DOMINATED BY A SURFACE TROUGH/FRONTAL BOUNDARY STALLING OVER THE MID ATLANTIC...WITH THE UPPER LEVEL TROUGH DIGGING SOUTH INTO CENTRAL NC. GOOD MOISTURE ADVECTION FROM THE GULF IN SOUTHWEST FLOW ALONG THE TROUGH AXIS WILL MOISTEN THE COLUMN...WITH PW`S AROUND TWO INCHES FORECAST THROUGH TUESDAY NIGHT. DISTURBANCES TRACKING OVER THE AREA ALONG THE BASE OF THE MID/UPPER TROUGH WILL BE SUFFICIENT TO INITIATE CONVECTION...ESPECIALLY DURING THE AFT/EVE...GIVEN THE MOIST AND UNSTABLE AIRMASS IN PLACE. CONFIDENCE ON EXACTLY WHERE THE BEST CHANCES/COVERAGE OF SHOWERS AND STORMS WILL OCCUR IS STILL LOW GIVEN THE UNCERTAINTY OF WHERE THE FRONT WILL STALL. FOR NOW WILL CONTINUE TO CARRY AT LEAST A CHANCE OF SHOWERS AND STORMS THROUGH THE PERIOD...WITH HIGHEST CHANCES DURING THE AFT/EVE. WITH THE CURRENT CHANCES OF CONVECTION AND GIVEN THE INCREASE IN MOISTURE EXPECTED...CLOUDY CONDITIONS WILL BE LIKELY OVER CENTRAL NC DURING THIS TIME. TAKING CLOUDS AND PRECIP INTO ACCOUNT...HIGH TEMPS IN THE MID 80S TO NEAR 90 DEGREES AND OVERNIGHT LOWS IN THE UPPER 60S TO LOW 70S ARE EXPECTED THROUGH THE PERIOD. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 1205 PM FRIDAY... VFR CONDITIONS ARE CURRENTLY BEING REPORTED ACROSS MOST OF CENTRAL NC. THIS IS EXPECTED TO REMAIN THE CASE THROUGH THE 24 HOUR TAF PERIOD...WITH THE EXCEPTION OF A FEW ISOLD TSTMS DURING THE REST OF THIS AFTERNOON AND EARLY EVENING THAT MAY BRIEFLY REDUCE FLT CONDITIONS TO MVFR. BEYOND THE 24 HOUR TAF PERIOD: OUTSIDE OF SOME EARLY MORNING FOG/STRATUS SATURDAY...VFR CONDITIONS SHOULD PREVAIL WITH ONLY ISOLATED AFTERNOON STORMS. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY AND WILL STALL ACROSS THE AREA THROUGH EARLY NEXT WEEK. THIS WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...WITH SUB VFR CONDITIONS IN HEAVY RAIN. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/DJF SHORT TERM...CBL LONG TERM...KC AVIATION...NP/CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1020 AM EDT FRI JUL 19 2013 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL EXTEND INTO THE AREA THROUGH SATURDAY. A COLD FRONT WILL APPROACH THE CAROLINAS ON SUNDAY AND THEN STALL ACROSS THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1020 AM FRIDAY... 12Z SOUNDINGS FROM AROUND THE AREA SHOWED A MODEST CAP AROUND 700MB AT KMHX...WITH THE CAP AT THAT LEVEL MUCH WEAKER TOWARD KGSO GIVEN TEMPERATURES 2C TO 3C COOLER. THE LATEST RUC INDICATES GENERAL SUBSIDENCE OVER CENTRAL NORTH CAROLINA THIS AFTERNOON...WITH WEAK WINDS ALOFT AND THE MOST FAVORABLE ITEMS FOR ANY RELATIVELY DEEP LIFT BEING THE SURFACE TROUGH LINGERING OVER THE WESTERN PIEDMONT... COUPLED WITH A WEAK 850MB TROUGH IN THE SAME AREA AND AVAILABLE LOW-LEVEL MOISTURE. OVERALL MOISTURE SHOULD BE BEST TOWARD THE NORTHWEST PIEDMONT LATER THIS AFTERNOON WHERE HIGHER 850MB THETA-E VALUES ARE FORECAST. IT IS ALSO IN THAT LOCATION WHERE THE BETTER 1000-500MB LAPSE RATES ARE FORECAST...NEAR 6.75C/KM...AND WHERE THE BETTER INSTABILITY LIES...2000-2500J/KG VERSUS A FORECAST OF ONLY 1000-1500J/KG TOWARD THE COASTAL PLAIN. CONVECTION-ALLOWING MODELS...GIVEN THE GENERAL SUBSIDENCE...ARE MOSTLY RELUCTANT TO FORECAST MUCH PRECIPITATION IN CENTRAL NORTH CAROLINA...BUT WITHIN THE SLIGHT CHANCE RANGE...THE BETTER CHANCE SHOULD MAINLY BE ALONG AND NORTH/WEST OF INTERSTATE 85. AS NOTED PREVIOUSLY...WEAK WINDS ALOFT WILL ALLOW ANY OF THE ISOLATED STORMS TO MOVE ONLY VERY SLOWLY. 1000-850MB THICKNESSES AT 12Z AND FORECAST LATE THIS AFTERNOON ARE BASICALLY PERSISTENCE FROM THURSDAY...AND HAVE FORECAST HIGHS CLOSE TO THOSE OF THURSDAY AS A RESULT. THIS PLACES MOST LOCATIONS WITH HEAT INDICES AROUND 100...A COUPLE OF DEGREES WARMER TOWARD KIXA AND KRZZ. ANY THUNDERSTORMS SHOULD DIMINISH DIURNALLY...WITH OVERNIGHT LOWS IN THE LOWER TO MID 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 245 AM FRIDAY... THE NORTHERN STREAM TROUGH AND ASSOCIATED SFC COLD FRONT WILL REMAIN NORTH OF THE AREA...SAGGING SOUTH INTO THE SOUTHERN OHIO VALLEY AND NORTHERN MID-ATLANTIC STATES BY SUNDAY MORNING. NOT MANY DIFFERENCES BETWEEN TODAY AND SATURDAY WITH THE SAME MESOSCALE FORCING DRIVING ISOLATED TO SCATTERED DIURNAL CONVECTION SATURDAY AFTERNOON HIGHS IN THE LOWER 90S. LOWS IN THE LOWER TO MID 70S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 230 AM FRIDAY... SUNDAY THROUGH THURSDAY: THIS PERIOD WILL BE DOMINATED BY A SURFACE TROUGH/FRONTAL BOUNDARY STALLING OVER THE MID ATLANTIC...WITH THE UPPER LEVEL TROUGH DIGGING SOUTH INTO CENTRAL NC. GOOD MOISTURE ADVECTION FROM THE GULF IN SOUTHWEST FLOW ALONG THE TROUGH AXIS WILL MOISTEN THE COLUMN...WITH PW`S AROUND TWO INCHES FORECAST THROUGH TUESDAY NIGHT. DISTURBANCES TRACKING OVER THE AREA ALONG THE BASE OF THE MID/UPPER TROUGH WILL BE SUFFICIENT TO INITIATE CONVECTION...ESPECIALLY DURING THE AFT/EVE...GIVEN THE MOIST AND UNSTABLE AIRMASS IN PLACE. CONFIDENCE ON EXACTLY WHERE THE BEST CHANCES/COVERAGE OF SHOWERS AND STORMS WILL OCCUR IS STILL LOW GIVEN THE UNCERTAINTY OF WHERE THE FRONT WILL STALL. FOR NOW WILL CONTINUE TO CARRY AT LEAST A CHANCE OF SHOWERS AND STORMS THROUGH THE PERIOD...WITH HIGHEST CHANCES DURING THE AFT/EVE. WITH THE CURRENT CHANCES OF CONVECTION AND GIVEN THE INCREASE IN MOISTURE EXPECTED...CLOUDY CONDITIONS WILL BE LIKELY OVER CENTRAL NC DURING THIS TIME. TAKING CLOUDS AND PRECIP INTO ACCOUNT...HIGH TEMPS IN THE MID 80S TO NEAR 90 DEGREES AND OVERNIGHT LOWS IN THE UPPER 60S TO LOW 70S ARE EXPECTED THROUGH THE PERIOD. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... AS OF 1020 AM FRIDAY... VFR CONDITIONS WILL PREVAIL OUTSIDE OF ANY AFTERNOON AND EVENING SHOWER OR THUNDERSTORM. DEEP CONVECTIVE COVERAGE THIS AFTERNOON AND EVENING IS EXPECTED TO BE RATHER ISOLATED AND THUS HAVE OMITTED ANY MENTION OF SHOWERS OR THUNDER FROM ALL TAF SITES. BEYOND THE 24 HOUR TAF PERIOD: OUTSIDE OF SOME EARLY MORNING FOG/STRATUS SATURDAY...VFR CONDITIONS SHOULD PREVAIL WITH ONLY ISOLATED AFTERNOON STORMS. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY AND WILL STALL ACROSS THE AREA THROUGH EARLY NEXT WEEK. THIS WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS...WITH SUB VFR CONDITIONS IN HEAVY RAIN. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/DJF SHORT TERM...CBL LONG TERM...KC AVIATION...CBL/DJF
AREA FORECAST DISCUSSION
NWS BISMARCK ND
834 PM CDT SAT JUL 20 2013 .UPDATE... ISSUED AT 834 PM CDT SAT JUL 20 2013 LATEST REGIONAL RADAR SHOWS AN AREA OF SEVERE THUNDERSTORMS IN EASTERN MONTANA MOVING SOUTHEAST WITH TIME. MONITORING FOR ANY OUTFLOWS...WITH CURRENT MOVEMENT INDICATING THAT THIS AREA COULD MOVE INTO OUR FAR SOUTHWESTERN COUNTIES OF GOLDEN VALLEY/SLOPE/BOWMAN IN THE NEXT COUPLE OF HOURS. OTHERWISE EXPECT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS OVERNIGHT...WITH INCREASING WARM AIR ADVECTION ASSOCIATED WITH A WARM FRONT OVER EASTERN MONTANA. STILL SOME ISOLATED CONVECTION IN NORTHWESTERN SOUTH DAKOTA BUT NOTHING SEVERE AT THIS TIME. MINOR CHANGES FROM PREVIOUS FORECAST. UPDATE ISSUED AT 559 PM CDT SAT JUL 20 2013 REGIONAL RADAR IMAGERY SHOWS A COUPLE OF AREAS TO WATCH THIS EVENING. FIRST IS IN OUR SOUTHWEST...WITH A SEVERE THUNDERSTORM WATCH BOX UP TO OUR SOUTHWEST BORDER FROM SOUTH DAKOTA. THUNDERSTORMS CONTINUE TO REMAIN SOUTH OF THE BORDER...BUT COULD DEVELOP A BIT FURTHER NORTH WITH AN AGITATED CUMULUS FIELD EVIDENT NEAR BAKER AND ALONG OUR FAR SOUTHWESTERN ZONES. THE OTHER AREA WAS SEEN OVER NORTHEASTERN MONTANA WITH SEVERE THUNDERSTORMS ROLLING OUT OF SOUTHERN SASKATCHEWAN AND INTO NORTHERN MONTANA. WILL CONTINUE TO MONITOR DEVELOPMENT OF THESE THUNDERSTORMS FURTHER EAST THIS EVENING AND OVERNIGHT...AS WHAT IS BEING INDICATED BY THE HRRR (HIGH RESOLUTION RAPID REFRESH MODEL)...AS WELL AS THE OTHER SHORT TERM MODELS. WARM AIR ADVECTION INCREASES OVERNIGHT AS NAM/GFS SOUNDINGS SHOW MODERATE VEERING WIND PROFILES FROM THE SFC TO 750MB. EXPECTING AN INCREASE IN THE AREAL COVERAGE OF SHOWERS/ELEVATED THUNDERSTORMS THROUGH EARLY SUNDAY MORNING...AS THEY CONTINUE TO DEVELOP ALONG A WARM FRONT IN EASTERN MONTANA. NAM/GFS SOUNDINGS SHOW DECENT INSTABILITY/CAPE ABOVE 750MB OVERNIGHT...WITH SHOWALTER INDICES SHOWING AN INCREASED POTENTIAL FOR ELEVATED THUNDERSTORMS WEST OF MINOT THROUGH 12Z SUNDAY. THUS WILL CONTINUE TO MENTION ISOLATED TO SCATTERED THUNDERSTORMS WEST...AND JUST INTO PORTIONS OF CENTRAL NORTH DAKOTA OVERNIGHT. WILL MONITOR FOR ANY SEVERE POTENTIAL DURING THE EVENING/OVERNIGHT. MOST OF WESTERN AND CENTRAL NORTH DAKOTA GET INTO THE WARM SECTOR BY LATE MORNING AND EARLY AFTERNOON SUNDAY...SETTING THE STAGE FOR SEVERE THUNDERSTORMS ALONG AND AHEAD OF AN ADVANCING COLD FRONT. SEE PREVIOUS DISCUSSION BELOW FOR MORE DETAILS. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 310 PM CDT SAT JUL 20 2013 MAIN CONCERNS THIS PERIOD WILL BE THUNDERSTORMS ASSOCIATED WITH A WARM FRONT EXTENDED ACROSS EASTERN MONTANA THAT IS FORECAST TO TRACK EAST ACROSS THE STATE LATE TONIGHT AND SUNDAY. SATELLITE LOOPS SHOW CLOUD COVER ACROSS WESTERN NORTH DAKOTA IN LOW LEVEL MOIST UP SLOPE FLOW. A BAND OF MID LEVEL SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING THROUGH SOUTH CENTRAL NORTH DAKOTA. THIS IS EXPECTED TO DIMINISH AS IT MOVES EAST. THE FOCUS FOR TONIGHT AND SUNDAY WILL BE THE WARM FRONT IN EASTERN MONTANA THIS WILL BE PROVIDE LIFT AND WITH A SHORT WAVE TROUGH SUPPORT THUNDERSTORMS ACROSS THE NORTHWEST...AND THEN THE NORTH CENTRAL ON SUNDAY. ADDED THE MENTION OF SEVERE WHERE SPC HAS DEFINED THE SLIGHT RISK SUNDAY AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 315 PM CDT SAT JUL 20 2013 THE RISK OF SEVERE WEATHER CONTINUES FROM SUNDAY AFTERNOON INTO THE NIGHT...MAINLY OVER THE CENTRAL AND EASTERN PARTS OF THE FORECAST AREA. LONG TERM MODELS ARE IN AGREEMENT THROUGH THE PERIOD ON THE BIG PICTURE...NAMELY THAT THE H5 RIDGE OFF THE SOUTHWEST COAST BUILDS EAST INTO THE DESERT SOUTHWEST AND EXPENDS NORTH INTO THE NORTHERN ROCKIES AND AMPLIFIES. THIS KEEPS A WEAK NORTHWEST FLOW OVER NORTH DAKOTA WITH CHANCES FOR THUNDERSTORMS COMING AS RIDGE RIDER SHORT WAVES CREST THE RIDGE AND PASS THROUGH EVERY OTHER DAY. THIS PATTERN IS ENHANCED AS AN H5 LOW CUTS OFF OVER ONTARIO AND SENDS A TROUGH AXIS THROUGH DURING THE THURSDAY-FRIDAY TIME FRAME. THAT...AS INDICATED IN THE PREVIOUS LONG TERM DISCUSSION...WILL BE THE GREATEST CHANCES FOR STORMS IN THE LONG TERM...AFTER SUNDAY NIGHT. BUT AGAIN...THERE ARE CHANCES ABOUT EVERY DAY AS TIMING OF THE WAVES WILL LIKELY CHANGE FROM FORECAST TO FORECAST. TEMPERATURES SHOULD BE FAIRLY STEADY IN THE PATTERN...AND NOT TOO FAR FROM NORMAL...GENERALLY IN THE MID 70S NORTHEAST TO MID 80S SOUTHWEST AND LOWS IN THE 50S TO LOWER 60S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 559 PM CDT SAT JUL 20 2013 LATEST SATELLITE AND RADAR IMAGERY SHOWS SCT/BKN VFR CIGS WITH DRY CONDITIONS AT THE AERODROMES. AN AREA OF SHOWERS AND THUNDERSTORMS IN NORTHEASTERN MONTANA WILL BEGIN TO SHIFT EAST OVERNIGHT...PRODUCING A MENTION FOR PREDOMINANT SHOWERS AND A VCTS AT KMOT/KBIS BY 09Z SUNDAY. ALTHOUGH VFR CIGS/VSBYS ARE ANTICIPATED NEXT 24HR...ANY OF THE STRONGER SHOWERS OR THUNDERSTORMS MAY RESULT IN BRIEF PERIODS OF MVFR/LOW VFR CIGS/VSBYS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...WAA LONG TERM...JPM AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1150 AM CDT FRI JUL 19 2013 .UPDATE... ISSUED AT 1138 AM CDT FRI JUL 19 2013 LATE THIS MORNING...THE VISIBLE SATELLITE LOOP SHOWS A CLUSTER OF SHOWERS NEAR REGINA SASKATCHEWAN...MOVING SOUTHEAST. OTHERWISE JUST A FEW CLOUDS WERE ALONG THE NORTH DAKOTA - CANADIAN BORDER. CURRENT THINKING STILL ASSUMES THE SHOWERS ASSOCIATED WITH A COLD FRONTAL BOUNDARY MOVING THROUGH SOUTHERN CANADA WILL TRACK INTO/DEVELOP ACROSS THE NORTHWEST LATE THIS AFTERNOON. OTHERWISE MOSTLY SUNNY SKIES AND COOLER AND DRIER WEATHER FORECAST THROUGH TODAY. CURRENT FORECAST LOOKING GOOD. UPDATE ISSUED AT 932 AM CDT FRI JUL 19 2013 FRIDAY MORNING...THE CURRENT WEATHER CONDITIONS WERE DEFINED BY A POST FRONTAL ENVIRONMENT WITH MOSTLY CLEAR SKIES AND LIGHT NORTHWEST WINDS. THIS UPDATE WILL BE MAINLY TO PROVIDE CURRENT TEMPERATURES AND RELATIVE HUMIDITY. THIS AFTERNOON...ANOTHER FRONTAL SYSTEM WILL APPROACH FROM THE NORTHWEST AND BRING A SLIGHT CHANCE FOR THUNDERSTORMS. CURRENT FORECAST LOOKS GOOD IN THIS REGARD. UPDATE ISSUED AT 627 AM CDT FRI JUL 19 2013 NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA EARLY THIS MORNING SO LOWERED CLOUD COVER THIS MORNING ACROSS THE NORTH. DO EXPECT INCREASING CLOUDS NORTH BY MID MORNING WITH SHOWER AND THUNDERSTORM CHANCES HOLDING OFF UNTIL AFTERNOON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE HIGHLIGHT OF THE SHORT TERM IS THE CONVECTIVE POTENTIAL THIS AFTERNOON THROUGH TONIGHT. AS OF 0830 UTC...A COLD FRONT WAS ANALYZED FROM NORTHEAST MANITOBA...ARCHING SOUTHWEST ACROSS NORTHERN LAKE WINNIPEG AND INTO CENTRAL SASKATCHEWAN. THIS FRONT IS FORECAST TO CONTINUE TO PROPAGATE SOUTH TODAY...CROSSING INTO THE NORTHERN PORTIONS OF NORTH DAKOTA BY 20-22 UTC. THIS FEATURE WILL BE THE FOCUS FOR CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND THROUGH THE NIGHT. THE 00 UTC 4 KM WRF AND 06 UTC HRRR SUGGEST SURFACE BASED CONVECTION ENTERING NORTH DAKOTA WITHIN THE 20-22 UTC TIME FRAME AND PROPAGATING SOUTH THROUGH THE EVENING AND OVERNIGHT WITH THE FRONT. CANNOT RULE OUT AN ISOLATED LOW END SEVERE STORM GIVEN ML CAPE VALUES AROUND 1000 J/KG AND DEEP LAYER SHEAR OF 40 KTS. HOWEVER...GIVEN WEAK UPPER LEVEL FORCING...THE THREAT SEEMS MARGINAL WITH WESTERN AND CENTRAL NORTH DAKOTA ONLY IN GENERAL THUNDER IN THE SPC DAY 1 OUTLOOK. THERE IS SOME UNCERTAINTY AS TO HOW LONG AFTER SUNSET CONVECTION CAN SUSTAIN ITSELF...WITH WEAK UPPER LEVEL FORCING AND THE LACK OF A LOW LEVEL JET. THE 00 UTC DETERMINISTIC SUITE SUGGESTS ISOLATED TO SCATTERED CONVECTION CONTINUING IN THE VICINITY OF THE FRONT THROUGH THE NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE LONG TERM PERIOD WILL CONSIST OF A NORTHWEST UPPER FLOW PATTERN WITH IMPULSES TRANSLATING THROUGH THE POLAR JET AND AFFECTING THE LOCAL AREA ABOUT EVERY 18-24 HOURS THROUGH THE ENTIRE PERIOD. THIS WILL RESULT IN A SEASONABLE TEMPERATURE REGIME WITH DAYTIME HIGHS MAINLY IN THE MID 70S NORTHEAST TO THE MID 80S SOUTHWEST...AND OVERNIGHT LOWS IN THE MID 50S TO LOWER 60S. FOR PRECIPITATION...A MODEL BLEND WAS UTILIZED DUE TO THE UNCERTAINTY OF TIMING AND PLACEMENT OF INDIVIDUAL IMPULSES MOVING THROUGH THE MEAN UPPER LEVEL FLOW. ON SATURDAY...SURFACE HIGH PRESSURE TO OUR NORTH AND EAST WILL RESULT IN A COOLER EASTERLY FLOW. 00 UTC FRI 19 JULY NAM/GFS FORECAST SOUNDINGS FOR SATURDAY INDICATE A STABLE ATMOSPHERE OVER CENTRAL NORTH DAKOTA WITH MID LEVEL SHORTWAVE ENERGY PRODUCING SHOWERS. THE WEST APPEARS TO BE THE AREA TO SEE ANY LATE MORNING OR AFTERNOON CONVECTION. THEREFORE LIMITED CONVECTION TO AREAS WEST OF BISMARCK AND MINOT ON SATURDAY. WE ALSO CUT BACK ON THE FORECAST HIGHS ACROSS THE NORTHEAST THIRD OF THE CWA...WITH UPPER 60S FORECAST FOR AREAS SUCH AS BOTTINEAU AND RUGBY. THE SOUTHWEST IS STILL FORECAST TO CLIMB INTO THE LOWER TO MIDDLE 80S. NO SIGNIFICANT CHANGES FROM THE MODEL BLEND SOLUTION WERE MADE TO THE REMAINDER OF THE EXTENDED FORECAST...RESULTING IN AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS EACH DAY FOR AT LEAST A PORTION OF THE CWA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1138 AM CDT FRI JUL 19 2013 AT 11 AM CDT...SKIES WERE MOSTLY CLEAR. VFR CONDITIONS ARE OBSERVED AND ARE FORECAST THROUGH THE 18Z TAF PERIOD. A WEAK COLD FRONTAL BOUNDARY ACROSS SOUTHERN CANADA WILL BE THE FOCUS FOR ISOLATED THUNDERSTORMS ACROSS NORTHERN NORTH DAKOTA AFTER 22Z...AND ACROSS THE SOUTH AFTER 00Z. THUNDERSTORMS SHOULD BE TOO ISOLATED TO ACCURATELY FORECAST...SO PLAN TO CONTINUE TO EXPRESS THE THUNDERSTORM HAZARD VIA VCTY (VICINITY). && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...AYD LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
944 AM CDT FRI JUL 19 2013 .UPDATE... ISSUED AT 932 AM CDT FRI JUL 19 2013 FRIDAY MORNING...THE CURRENT WEATHER CONDITIONS WERE DEFINED BY A POST FRONTAL ENVIRONMENT WITH MOSTLY CLEAR SKIES AND LIGHT NORTHWEST WINDS. THIS UPDATE WILL BE MAINLY TO PROVIDE CURRENT TEMPERATURES AND RELATIVE HUMIDITY. THIS AFTERNOON...ANOTHER FRONTAL SYSTEM WILL APPROACH FROM THE NORTHWEST AND BRING A SLIGHT CHANCE FOR THUNDERSTORMS. CURRENT FORECAST LOOKS GOOD IN THIS REGARD. UPDATE ISSUED AT 627 AM CDT FRI JUL 19 2013 NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA EARLY THIS MORNING SO LOWERED CLOUD COVER THIS MORNING ACROSS THE NORTH. DO EXPECT INCREASING CLOUDS NORTH BY MID MORNING WITH SHOWER AND THUNDERSTORM CHANCES HOLDING OFF UNTIL AFTERNOON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE HIGHLIGHT OF THE SHORT TERM IS THE CONVECTIVE POTENTIAL THIS AFTERNOON THROUGH TONIGHT. AS OF 0830 UTC...A COLD FRONT WAS ANALYZED FROM NORTHEAST MANITOBA...ARCHING SOUTHWEST ACROSS NORTHERN LAKE WINNIPEG AND INTO CENTRAL SASKATCHEWAN. THIS FRONT IS FORECAST TO CONTINUE TO PROPAGATE SOUTH TODAY...CROSSING INTO THE NORTHERN PORTIONS OF NORTH DAKOTA BY 20-22 UTC. THIS FEATURE WILL BE THE FOCUS FOR CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND THROUGH THE NIGHT. THE 00 UTC 4 KM WRF AND 06 UTC HRRR SUGGEST SURFACE BASED CONVECTION ENTERING NORTH DAKOTA WITHIN THE 20-22 UTC TIME FRAME AND PROPAGATING SOUTH THROUGH THE EVENING AND OVERNIGHT WITH THE FRONT. CANNOT RULE OUT AN ISOLATED LOW END SEVERE STORM GIVEN ML CAPE VALUES AROUND 1000 J/KG AND DEEP LAYER SHEAR OF 40 KTS. HOWEVER...GIVEN WEAK UPPER LEVEL FORCING...THE THREAT SEEMS MARGINAL WITH WESTERN AND CENTRAL NORTH DAKOTA ONLY IN GENERAL THUNDER IN THE SPC DAY 1 OUTLOOK. THERE IS SOME UNCERTAINTY AS TO HOW LONG AFTER SUNSET CONVECTION CAN SUSTAIN ITSELF...WITH WEAK UPPER LEVEL FORCING AND THE LACK OF A LOW LEVEL JET. THE 00 UTC DETERMINISTIC SUITE SUGGESTS ISOLATED TO SCATTERED CONVECTION CONTINUING IN THE VICINITY OF THE FRONT THROUGH THE NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE LONG TERM PERIOD WILL CONSIST OF A NORTHWEST UPPER FLOW PATTERN WITH IMPULSES TRANSLATING THROUGH THE POLAR JET AND AFFECTING THE LOCAL AREA ABOUT EVERY 18-24 HOURS THROUGH THE ENTIRE PERIOD. THIS WILL RESULT IN A SEASONABLE TEMPERATURE REGIME WITH DAYTIME HIGHS MAINLY IN THE MID 70S NORTHEAST TO THE MID 80S SOUTHWEST...AND OVERNIGHT LOWS IN THE MID 50S TO LOWER 60S. FOR PRECIPITATION...A MODEL BLEND WAS UTILIZED DUE TO THE UNCERTAINTY OF TIMING AND PLACEMENT OF INDIVIDUAL IMPULSES MOVING THROUGH THE MEAN UPPER LEVEL FLOW. ON SATURDAY...SURFACE HIGH PRESSURE TO OUR NORTH AND EAST WILL RESULT IN A COOLER EASTERLY FLOW. 00 UTC FRI 19 JULY NAM/GFS FORECAST SOUNDINGS FOR SATURDAY INDICATE A STABLE ATMOSPHERE OVER CENTRAL NORTH DAKOTA WITH MID LEVEL SHORTWAVE ENERGY PRODUCING SHOWERS. THE WEST APPEARS TO BE THE AREA TO SEE ANY LATE MORNING OR AFTERNOON CONVECTION. THEREFORE LIMITED CONVECTION TO AREAS WEST OF BISMARCK AND MINOT ON SATURDAY. WE ALSO CUT BACK ON THE FORECAST HIGHS ACROSS THE NORTHEAST THIRD OF THE CWA...WITH UPPER 60S FORECAST FOR AREAS SUCH AS BOTTINEAU AND RUGBY. THE SOUTHWEST IS STILL FORECAST TO CLIMB INTO THE LOWER TO MIDDLE 80S. NO SIGNIFICANT CHANGES FROM THE MODEL BLEND SOLUTION WERE MADE TO THE REMAINDER OF THE EXTENDED FORECAST...RESULTING IN AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS EACH DAY FOR AT LEAST A PORTION OF THE CWA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 932 AM CDT FRI JUL 19 2013 AT 9 AM CDT...VFR CONDITIONS WITH CLEAR SKIES COVERED THE REGION. LATE THIS AFTERNOON ANOTHER WEAK COLD FRONTAL BOUNDARY WILL APPROACH THE STATE FROM THE NORTHWEST. THE FRONT WILL BE THE FOCUS FOR WIDELY SCATTERED THUNDERSTORMS. AT THIS TIME...TO MUCH UNCERTAINTY TO ADD THUNDERSTORMS TO THE TAF. CURRENT 12Z TAFS EXPRESS THE THUNDERSTORM THREAT AS VCTS (VICINITY) THUNDERSTORMS AFTER 22Z NORTH AND AFTER 00Z SOUTH. WILL RE EVALUATE THE TIMING FOR THE 18Z TAF ISSUANCE BUT THREAT WILL PROBABLY BE TO ISOLATED TO ADD MORE DEFINITION THAN CURRENT TAFS EXPRESS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...AYD LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
627 AM CDT FRI JUL 19 2013 .UPDATE... ISSUED AT 627 AM CDT FRI JUL 19 2013 NO SIGNIFICANT CHANGES TO THE CURRENT FORECAST. CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA EARLY THIS MORNING SO LOWERED CLOUD COVER THIS MORNING ACROSS THE NORTH. DO EXPECT INCREASING CLOUDS NORTH BY MID MORNING WITH SHOWER AND THUNDERSTORM CHANCES HOLDING OFF UNTIL AFTERNOON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE HIGHLIGHT OF THE SHORT TERM IS THE CONVECTIVE POTENTIAL THIS AFTERNOON THROUGH TONIGHT. AS OF 0830 UTC...A COLD FRONT WAS ANALYZED FROM NORTHEAST MANITOBA...ARCHING SOUTHWEST ACROSS NORTHERN LAKE WINNIPEG AND INTO CENTRAL SASKATCHEWAN. THIS FRONT IS FORECAST TO CONTINUE TO PROPAGATE SOUTH TODAY...CROSSING INTO THE NORTHERN PORTIONS OF NORTH DAKOTA BY 20-22 UTC. THIS FEATURE WILL BE THE FOCUS FOR CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND THROUGH THE NIGHT. THE 00 UTC 4 KM WRF AND 06 UTC HRRR SUGGEST SURFACE BASED CONVECTION ENTERING NORTH DAKOTA WITHIN THE 20-22 UTC TIME FRAME AND PROPAGATING SOUTH THROUGH THE EVENING AND OVERNIGHT WITH THE FRONT. CANNOT RULE OUT AN ISOLATED LOW END SEVERE STORM GIVEN ML CAPE VALUES AROUND 1000 J/KG AND DEEP LAYER SHEAR OF 40 KTS. HOWEVER...GIVEN WEAK UPPER LEVEL FORCING...THE THREAT SEEMS MARGINAL WITH WESTERN AND CENTRAL NORTH DAKOTA ONLY IN GENERAL THUNDER IN THE SPC DAY 1 OUTLOOK. THERE IS SOME UNCERTAINTY AS TO HOW LONG AFTER SUNSET CONVECTION CAN SUSTAIN ITSELF...WITH WEAK UPPER LEVEL FORCING AND THE LACK OF A LOW LEVEL JET. THE 00 UTC DETERMINISTIC SUITE SUGGESTS ISOLATED TO SCATTERED CONVECTION CONTINUING IN THE VICINITY OF THE FRONT THROUGH THE NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE LONG TERM PERIOD WILL CONSIST OF A NORTHWEST UPPER FLOW PATTERN WITH IMPULSES TRANSLATING THROUGH THE POLAR JET AND AFFECTING THE LOCAL AREA ABOUT EVERY 18-24 HOURS THROUGH THE ENTIRE PERIOD. THIS WILL RESULT IN A SEASONABLE TEMPERATURE REGIME WITH DAYTIME HIGHS MAINLY IN THE MID 70S NORTHEAST TO THE MID 80S SOUTHWEST...AND OVERNIGHT LOWS IN THE MID 50S TO LOWER 60S. FOR PRECIPITATION...A MODEL BLEND WAS UTILIZED DUE TO THE UNCERTAINTY OF TIMING AND PLACEMENT OF INDIVIDUAL IMPULSES MOVING THROUGH THE MEAN UPPER LEVEL FLOW. ON SATURDAY...SURFACE HIGH PRESSURE TO OUR NORTH AND EAST WILL RESULT IN A COOLER EASTERLY FLOW. 00 UTC FRI 19 JULY NAM/GFS FORECAST SOUNDINGS FOR SATURDAY INDICATE A STABLE ATMOSPHERE OVER CENTRAL NORTH DAKOTA WITH MID LEVEL SHORTWAVE ENERGY PRODUCING SHOWERS. THE WEST APPEARS TO BE THE AREA TO SEE ANY LATE MORNING OR AFTERNOON CONVECTION. THEREFORE LIMITED CONVECTION TO AREAS WEST OF BISMARCK AND MINOT ON SATURDAY. WE ALSO CUT BACK ON THE FORECAST HIGHS ACROSS THE NORTHEAST THIRD OF THE CWA...WITH UPPER 60S FORECAST FOR AREAS SUCH AS BOTTINEAU AND RUGBY. THE SOUTHWEST IS STILL FORECAST TO CLIMB INTO THE LOWER TO MIDDLE 80S. NO SIGNIFICANT CHANGES FROM THE MODEL BLEND SOLUTION WERE MADE TO THE REMAINDER OF THE EXTENDED FORECAST...RESULTING IN AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS EACH DAY FOR AT LEAST A PORTION OF THE CWA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 627 AM CDT FRI JUL 19 2013 VFR CONDITIONS ARE FORECAST FOR THE 12 UTC TAF CYCLE OUTSIDE OF THUNDERSTORMS. INCLUDED VCTS FOR KISN AND KMOT BY 22-00 UTC AND KJMS AND KBIS BY 00-02 UTC AS A COLD FRONT MOVES SOUTH OUT OF CANADA. LEFT THE MENTION OF THUNDER OUT FOR NOW AT KDIK DUE TO UNCERTAINTY IN IMPACTS TO THE TERMINAL AS THE GREATER CHANCES FOR THUNDERSTORMS LOOK TO BE NORTH AND EAST. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...AYD LONG TERM...TWH AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
352 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE HIGHLIGHT OF THE SHORT TERM IS THE CONVECTIVE POTENTIAL THIS AFTERNOON THROUGH TONIGHT. AS OF 0830 UTC...A COLD FRONT WAS ANALYZED FROM NORTHEAST MANITOBA...ARCHING SOUTHWEST ACROSS NORTHERN LAKE WINNIPEG AND INTO CENTRAL SASKATCHEWAN. THIS FRONT IS FORECAST TO CONTINUE TO PROPAGATE SOUTH TODAY...CROSSING INTO THE NORTHERN PORTIONS OF NORTH DAKOTA BY 20-22 UTC. THIS FEATURE WILL BE THE FOCUS FOR CONVECTIVE DEVELOPMENT LATE THIS AFTERNOON AND THROUGH THE NIGHT. THE 00 UTC 4 KM WRF AND 06 UTC HRRR SUGGEST SURFACE BASED CONVECTION ENTERING NORTH DAKOTA WITHIN THE 20-22 UTC TIME FRAME AND PROPAGATING SOUTH THROUGH THE EVENING AND OVERNIGHT WITH THE FRONT. CANNOT RULE OUT AN ISOLATED LOW END SEVERE STORM GIVEN ML CAPE VALUES AROUND 1000 J/KG AND DEEP LAYER SHEAR OF 40 KTS. HOWEVER...GIVEN WEAK UPPER LEVEL FORCING...THE THREAT SEEMS MARGINAL WITH WESTERN AND CENTRAL NORTH DAKOTA ONLY IN GENERAL THUNDER IN THE SPC DAY 1 OUTLOOK. THERE IS SOME UNCERTAINTY AS TO HOW LONG AFTER SUNSET CONVECTION CAN SUSTAIN ITSELF...WITH WEAK UPPER LEVEL FORCING AND THE LACK OF A LOW LEVEL JET. THE 00 UTC DETERMINISTIC SUITE SUGGESTS ISOLATED TO SCATTERED CONVECTION CONTINUING IN THE VICINITY OF THE FRONT THROUGH THE NIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 352 AM CDT FRI JUL 19 2013 THE LONG TERM PERIOD WILL CONSIST OF A NORTHWEST UPPER FLOW PATTERN WITH IMPULSES TRANSLATING THROUGH THE POLAR JET AND AFFECTING THE LOCAL AREA ABOUT EVERY 18-24 HOURS THROUGH THE ENTIRE PERIOD. THIS WILL RESULT IN A SEASONABLE TEMPERATURE REGIME WITH DAYTIME HIGHS MAINLY IN THE MID 70S NORTHEAST TO THE MID 80S SOUTHWEST...AND OVERNIGHT LOWS IN THE MID 50S TO LOWER 60S. FOR PRECIPITATION...A MODEL BLEND WAS UTILIZED DUE TO THE UNCERTAINTY OF TIMING AND PLACEMENT OF INDIVIDUAL IMPULSES MOVING THROUGH THE MEAN UPPER LEVEL FLOW. ON SATURDAY...SURFACE HIGH PRESSURE TO OUR NORTH AND EAST WILL RESULT IN A COOLER EASTERLY FLOW. 00 UTC FRI 19 JULY NAM/GFS FORECAST SOUNDINGS FOR SATURDAY INDICATE A STABLE ATMOSPHERE OVER CENTRAL NORTH DAKOTA WITH MID LEVEL SHORTWAVE ENERGY PRODUCING SHOWERS. THE WEST APPEARS TO BE THE AREA TO SEE ANY LATE MORNING OR AFTERNOON CONVECTION. THEREFORE LIMITED CONVECTION TO AREAS WEST OF BISMARCK AND MINOT ON SATURDAY. WE ALSO CUT BACK ON THE FORECAST HIGHS ACROSS THE NORTHEAST THIRD OF THE CWA...WITH UPPER 60S FORECAST FOR AREAS SUCH AS BOTTINEAU AND RUGBY. THE SOUTHWEST IS STILL FORECAST TO CLIMB INTO THE LOWER TO MIDDLE 80S. NO SIGNIFICANT CHANGES FROM THE MODEL BLEND SOLUTION WERE MADE TO THE REMAINDER OF THE EXTENDED FORECAST...RESULTING IN AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS EACH DAY FOR AT LEAST A PORTION OF THE CWA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 352 AM CDT FRI JUL 19 2013 VFR CONDITIONS ARE FORECAST FOR THE 06 UTC TAF CYCLE OUTSIDE OF THUNDERSTORMS. INCLUDED VCTS FOR KISN AND KMOT BY 22-00 UTC...CONTINUING THEREAFTER AS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE ALONG A COLD FRONT MOVING SOUTH FROM CANADA. KEPT THE MENTION OF THUNDERSTORMS OUT FOR KDIK...KBIS AND KJMS FOR NOW DUE TO UNCERTAINTY...AND WILL RE-EVALUATE WITH THE 12 UTC CYCLE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AYD LONG TERM...TWH AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CDT FRI JUL 19 2013 .UPDATE... ISSUED AT 1246 AM CDT FRI JUL 19 2013 NO CHANGES REQUIRED WITH THIS UPDATE OTHER THAN TO BLEND TO THE 05 UTC OBSERVED TRENDS IN THE WAKE OF THE COLD FRONT PROPAGATING INTO NORTHEAST MINNESOTA THROUGH SOUTHWEST SOUTH DAKOTA. UPDATE ISSUED AT 942 PM CDT THU JUL 18 2013 UPDATE TO REDUCE LATE EVENING POPS AND CONFINE AREA FROM THE TURTLE MOUNTAINS THROUGH FOSTER COUNTY. STRONG STORMS GLANCED THE FAR NORTHEAST EARLIER THIS EVENING BUT HAVE SINCE DISSIPATED WHILE CONVECTION CONTINUES TO THE EAST. CANNOT RULE OUT AN ISOLATED STORM OVER THE NEXT FEW HOURS...BUT THE PROBABILITY IS LOW. && .SHORT TERM...(THIS AFTERNOON THROUGH FRIDAY) ISSUED AT 250 PM CDT THU JUL 18 2013 THE MAIN FORECAST CONCERN FOR THE PERIOD WILL BE THUNDERSTORM CHANCES THIS AFTERNOON AND EVENING AS WELL AS THE SEVERE POTENTIAL. HEAT INDEX VALUES APPROACHING 100 DEGREES WILL CONTINUE ACROSS THE SOUTHERN JAMES RIVER BASIN AHEAD OF A COLD FRONT THROUGH THE LATE AFTERNOON. THEREFORE...WILL MAINTAIN THE CURRENT HEAT ADVISORY IN EFFECT THROUGH 00Z. IN ADDITION...THUNDERSTORMS ARE STILL PROGGED TO DEVELOP OVER THE JAMES RIVER BASIN IN AN AREA OF LARGE INSTABILITY CHARACTERIZED BY SURFACE-BASED CAPE VALUES OF 2500 J/KG. HOWEVER...MARGINAL TO LOW DEEP LAYER SHEAR IS EXPECTED TO KEEP THIS CONVECTION BELOW SEVERE LIMITS. THIS ACTIVITY SHOULD BE OUT OF THE JAMES RIVER BASIN BY 00Z THIS EVENING AS THE COLD FRONT PUSHES EAST OF THE CWA. AN UPPER WAVE OVER NORTHWESTERN NORTH DAKOTA WILL PIVOT ACROSS THE STATE TONIGHT. ONGOING CONVECTION OVER THE SOUTHERN CANADIAN PRAIRIES IS EXPECTED TO ENTER NORTH CENTRAL NORTH DAKOTA AFTER 23Z AS THE WAVE PIVOTS ACROSS THE REGION. THE 3KM HRRR AND 12Z WRF KEEP THE CONVECTION CONFINED TO AREAS NORTHEAST OF HIGHWAY 52 THROUGH 03Z. SOME STORMS MIGHT ALREADY BE SEVERE AS THEY CROSS THE BORDER. HOWEVER...THE SEVERE THREAT SHOULD DIMINISH AFTER 03Z WITH THE LOSS OF DAYTIME HEATING. WILL THEREFORE INTRODUCE SEVERE WORDING IN THE GRIDS FOR THE 23Z-03Z PERIOD FOR POINTS NORTH OF A LINE FROM MOHALL TO DEERING TO BALTA. FURTHERMORE...WILL CONTINUE TO HIGHLIGHT THIS THREAT IN THE HWO. AFTER 03Z...DRY CONDITIONS ARE EXPECTED AREAWIDE AS HIGH PRESSURE BUILDS INTO THE REGION. MUCH COOLER OVERNIGHT LOWS ARE EXPECTED WITH READINGS FROM THE MID 50S WEST TO THE LOWER 60S SOUTHEAST. FOR FRIDAY...HIGH PRESSURE WILL SLOWLY SINK SOUTHWARD INTO SOUTH DAKOTA. AS IT DOES...A WEAK BAROCLINIC ZONE IS PROGGED TO SET UP OVER NORTHERN NORTH DAKOTA. THIS FEATURE SHOULD PROVIDE FOCUS FOR AFTERNOON CONVECTION. GIVEN THE ELEVATED NATURE OF THE THUNDERSTORM POTENTIAL...THINK ANY CONVECTION THAT DOES DEVELOP WILL STAY BELOW SEVERE LIMITS. TEMPERATURES WILL BE MORE SEASONAL FRIDAY WITH HIGHS FROM THE UPPER 70S NORTH TO THE MID 80S SOUTH. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 250 PM CDT THU JUL 18 2013 THE LONG TERM PERIOD WILL BE CHARACTERIZED BY A NORTHWEST UPPER LEVEL FLOW PATTERN WITH PERIODIC EMBEDDED SHORTWAVES MOVING THROUGH THE FLOW. AT THIS TIME THE LONG TERM MODELS ARE DEPICTING SHORTWAVES MOVING THROUGH THE FORECAST AREA EACH DAY...KEEPING ISOLATED TO SCATTERED THUNDERSTORM ACTIVITY/CHANCES EACH DAY. THE LONG TERM BEGINS FRIDAY NIGHT WITH ANOTHER SURFACE COLD FRONT MOVING SOUTHWARD DURING THE DAYTIME FRIDAY...BECOMING STATIONARY FRIDAY NIGHT/SATURDAY AS DRY HIGH PRESSURE MOVES INTO NORTHEASTERN NORTH DAKOTA. EXPECT SCATTERED THUNDERSTORMS ALONG THIS BOUNDARY FROM NORTHWEST TO SOUTH CENTRAL/SOUTHEASTERN NORTH DAKOTA. PLENTY OF CAPE BUT LIMITED SHEAR WILL KEEP THE MENTION OF SEVERE STORMS OUT OF THE FORECAST. THE NEXT CHANCE OF SCATTERED THUNDERSTORMS APPEARS TO BE SUNDAY AFTERNOON/NIGHT...THEN AGAIN MONDAY AFTERNOON/NIGHT. AT THIS TIME IT APPEARS THAT WEDNESDAY MAY SEE A BREAK IN THE ACTION WITH DRY SURFACE HIGH PRESSURE DEPICTED AND A LULL IN THE SHORTWAVES ACROSS NORTH DAKOTA...BUT TIMING IS VERY IFFY WITH TIMING OF SHORTWAVES. ANOTHER SHORTWAVE WITH A SURFACE TROUGH/FRONT TRAVERSES THE FORECAST AREA THURSDAY. THUS ISOLATED TO SCATTERED THUNDERSTORMS NEARLY EACH DAY. THE COOLEST DAY SHOULD BE SATURDAY WITH HIGHS FROM THE 70S ALONG AND NORTH AND EAST OF THE MISSOURI RIVER WITH LOW TO MID 80S SOUTH AND WEST OF THE RIVER. OTHERWISE SEASONABLE TEMPERATURES WITH HIGHS MAINLY IN THE 80S AND LOWS IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1246 AM CDT FRI JUL 19 2013 VFR CONDITIONS ARE FORECAST FOR THE 06 UTC TAF CYCLE OUTSIDE OF THUNDERSTORMS. INCLUDED VCTS FOR KISN AND KMOT BY 22-00 UTC...CONTINUING THEREAFTER AS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE ALONG A COLD FRONT MOVING SOUTH FROM CANADA FRIDAY EVENING. KEPT THE MENTION OF THUNDERSTORMS OUT FOR KDIK...KBIS AND KJMS DUE TO UNCERTAINTY...AND WILL RE-EVALUATE WITH THE 12 UTC CYCLE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...TM LONG TERM...JV AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1137 PM CDT THU JUL 18 2013 .UPDATE... ISSUED AT 1130 PM CDT THU JUL 18 2013 WIDELY SCATTERED/ISOLATED CONVECTION CONTINUES ACROSS NORTHERN MN ASSOCIATED WITH SHORT WAVE TRACKING ALONG INTERNATIONAL BORDER. MAINTAINED SOME CHC POPS ACROSS NE THIRD OF FORECAST AREA FOR A FEW MORE HOURS BEFORE ANY CONVECTION SHOULD BE SHIFTING EAST OF FA. CELL ACROSS N BELTRAMI HAS STRENGTHENED SLIGHTLY HOWEVER STILL BELOW SEVERE LIMITS AND WILL ALLOW WATCH TO EXPIRE AT MIDNIGHT. TRIMMED POPS FARTHER WEST BEHIND BOUNDARIES FOR REMAINDER OF THE NIGHT. REMAINDER OF THE FORECAST BASICALLY UNCHANGED AS TEMPERATURES AND CLOUD TRENDS ON TRACK. UPDATE ISSUED AT 945 PM CDT THU JUL 18 2013 CONVECTION STRUGGLED ALL EVENING TO GET GOING ACROSS EASTERN FA ALONG PREFRONTAL TROUGH/WARM FRONT. ABOVE BOUNDARY CLOSE TO EXITING FA TO THE EAST AND NOW CONFINED TO HUBBARD/BELTRAMI COUNTY. TRIMMED BACK ON POPS THIS AREA. FARTHER NORTHWEST MORE ROBUST BUT WIDELY SCATTERED CONVECTION CONTINUES ALONG INTERNATIONAL BORDER AREA ASSOCIATED WITH SECONDARY BOUNDARY AND MID LEVEL WAVE RIDING ALONG INTERNATIONAL BORDER. HAVE HIGHEST POPS ALONG INTERNATIONAL BORDER INTO EARLY AM AS FEATURE CONTINUES TO PROPAGATE EAST IN MODERATELY UNSTABLE AIR MASS. ELSEWHERE ADJUSTED POPS ACCORDINGLY BASED ON CURRENT RADAR TRENDS. REMAINDER OF FORECAST UNCHANGED FOR THIS UPDATE. UPDATE ISSUED AT 645 PM CDT THU JUL 18 2013 DEEP CONVECTION BECOMING A LITTLE BETTER ORGANIZED ALONG FRONTAL BOUNDARY FROM NEAR FSE NE TO INL. SO FAR CELLS HAVE REMAINED BLO SVR LIMITS HOWEVER WILL CONTINUE TO MONITOR. FARTHER NW ISOLD SHRA/TSRA CLOSING IN ON FAR NW FA HOWEVER STRONGER STORMS STILL WELL NORTH OF INL BORDER AND CONFIDENCE NOT VERY HIGH ON SEVERE POTENTIAL THIS AREA. FOR NOW WITH STRENGTH OF MID LEVEL IMPULSE AND DEGREE OF INSTABILITY CANNOT RULE OUT ISLD STRONG STORM SO WILL MAINTAIN STRONGER STORM WORDING THIS AREA. MADE SOME MINOR POP ADJUSTMENTS THROUGH MID EVENING TRYING TO FINE TUNE AREAS FOR BEST STORM POTENTIAL ACROSS N CENTRAL MN. PULLED POPS ACROSS CENTRAL FA IN BETWEEN BOUNDARIES WHERE CONVECTION NOT ANTICIPATED. TEMPERATURES STILL WARM/HUMID BUT BLO HEAT ADVISORY CRITERIA SO WILL ALLOW TO EXPIRE ON TIME. ANY OTHER CHANGES MINIMAL THIS UPDATE. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 250 PM CDT THU JUL 18 2013 SEVERE POTENTIAL THIS EVENING WILL BE THE MAIN CONCERN. HEAT ADVISORY CONDITIONS ACROSS THE SOUTHERN FA WILL CONTINUE INTO THE EARLY EVENING HOURS. THE MAIN SEVERE RISK AREA WILL BE ALONG THE WARM FRONT FROM JUST EAST OF GRAND FORKS INTO BEMIDJI...AND LOCATIONS 50 MILES NORTH AND SOUTH OF THIS LINE. SPC SUPERCELL COMPOSITE AND SIGNIFICANT TORNADO PARAMETERS INDICATE THIS AREA WITH THE GREATEST POTENTIAL. 19Z LAPS ANALYSIS STILL INDICATES A STRONG CAP (MLCIN AOA 40 J/KG)...AND NOT SURE HOW WIDESPREAD INITIATION WILL BE. HRRR HAS BEEN CONSISTENT WITH DEVELOPING STORMS...AND WILL CONTINUE TO FOLLOW ITS COVERAGE AND INITIATION TIMES. ANTICIPATE SUPERCELL STORMS CAPABLE OF ALL MODES OF SEVERE WEATHER. THERE IS ANOTHER AREA OF CONCERN ACROSS THE NW FA AS THE UPPER WAVE APPROACHES THIS EVENING. AN AREA OF STORMS HAS DEVELOPED WELL TO THE NW IN SASKATCHEWAN (JUST AHEAD OF THE UPPER WAVE)...AND INSTABILITY SHOULD INCREASE JUST AHEAD OF THIS COMPLEX. THIS COMPLEX MAY STILL BE SEVERE AS IT MOVES INTO THE NW FA...AND QUICKLY WEAKEN BY MIDNIGHT. FRIDAY-FRIDAY NIGHT...ANOTHER COLD FRONT WILL MOVE INTO THE REGION ON FRIDAY. INSTABILITY WILL BE WEAK...BUT SHOULD BE ENOUGH FOR ISOLD SHOWERS AND POSSIBLY THUNDER FRIDAY AFTERNOON. SFC HIGH PRESSURE WILL BEGIN WORKING INTO THE REGION FROM THE NE FRIDAY NIGHT...AND MIN TEMPS BY SATURDAY MORNING SHOULD BE INTO THE 40S ACROSS NE MN (WARMER TO THE WEST AND SOUTH). .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 250 PM CDT THU JUL 18 2013 SATURDAY-SUNDAY...MODELS AGREE WITH NORTHWEST FLOW ALOFT AND SURFACE RIDGING ACROSS MUCH OF THE FA. THE SURFACE RIDGE GRADUALLY SHIFTS BACK TO THE EAST BY SUNDAY. THUNDER CHANCES WILL BE ON THE WESTERN EDGE OF THE FA ON SATURDAY...AND SHIFT TO THE EAST BY SUNDAY. FORCING AND INSTABILITY WILL BE WEAK...SO EXPECT ONLY ISOLD TO SCATTERED ACTIVITY. TEMPERATURES WILL BE BELOW NORMAL VALUES AS A RELATIVELY COLDER AIRMASS WILL BE ACROSS THE REGION. SUNDAY NIGHT-THURSDAY...LONG TERM MODELS ARE IN POOR AGREEMENT. IN GENERAL...ECMWF TRACK OF SFC LOWS TRANSITING SOUTHERN CANADA NEXT WEEK ARE MUCH FURTHER NORTH THAN THE GFS...WHICH BRINGS THEM ACROSS NORTHERN TIER OF CONUS. ECMWF ALSO CONTINUES TO PRODUCE A LOT OF QPF...WHICH SEEMS UNREALISTIC. THEY DO AGREE SOMEWHAT ON A NW FLOW UPPER AIR PATTERN BUT EVEN THAT DIVERGES BY DAY 6. THUS LOW POPS IN CONSALL IS A RESULT OF ECMWF BLENDED INTO THE SOLUTION. CONFIDENCE IS LOW BEYOND DAY 4 (NIGHT). BEST CHANCE APPEARS TO BE SUN NIGHT INTO MON MORNING...WHEN AN UPPER WAVE MOVES ACROSS THE AREA. BEST CHANCES WILL BE ACROSS THE NORTHEAST AND DO HAVE A FAIR DEGREE OF CONFIDENCE FOR 40S POPS ACROSS THE NORTH. GFS WOULD THEN GIVE US DRY WEATHER MON NIGHT AND I HAVE REMOVED CHANCE POPS FOR THIS PERIOD. GFS THEN BRINGS ANOTHER SFC LOW INTO NORTHERN TIER TUE NIGHT...FOR ANOTHER CHANCE OF SHOWERS/TSTMS ACROSS THE NORTH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1132 PM CDT THU JUL 18 2013 ISOLATED TSRA WILL CONTINUE ALONG AND NORTH OF A LINE FROM TVF TO BJI FOR A FEW MORE HOURS HOWEVER CIGS/VSBY TO REMAIN VFR. REMAINDER OF FA WILL REMAIN VFR THROUGH THE FORECAST PERIOD. CONFIDENCE NOT HIGH ENOUGH TO ADD PCPN MENTION TOMORROW AFTERNOON AHEAD OF NEXT COLD FRONT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...VOELKER SHORT TERM...TG LONG TERM...TG/SPEICHER AVIATION...VOELKER
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
143 PM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID AIR MASS OVER THE REGION WILL BREAK DOWN TONIGHT AS A COLD FRONT MOVES INTO THE REGION. STORMS WILL ACCOMPANY THE FRONT AS IT MOVES THROUGH THE AREA ON SATURDAY. COOLER AND DRIER WEATHER ON TAP FOR SUNDAY...BUT THE HUMIDITY WILL RETURN EARLY NEXT WEEK. TEMPERATURES WILL BE MORE COMFORTABLE WITH HIGHS AT OR SLIGHTLY BELOW NORMAL THROUGH MOST OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...MADE MINOR ADJUSTMENTS FOR THE NEXT SEVERAL DAYS. FOR TODAY ADDED A SLIGHT CHANCE TO THE NORTHWEST COUNTIES WHERE LIKE THE PAST FEW DAYS THE HRRR SHOWED AFTERNOON DEVELOPMENT. TEMPERATURES OVERNIGHT REMAINED HIGH IN THE MID 70S...WHICH WILL PROVIDE A WARM START FOR HEAT ADVISORY CONDITIONS LATER TODAY. LOOK FOR SCATTERED CLOUDS DEVELOPING THIS AFTERNOON...BUT NOT ENOUGH COVERAGE TO KEEP TEMPERATURES FROM RETURNING TO THE LOWER 90S...AND IN SOME W SITES IN THE MID 90S. EXPECT SOME LOW LEVEL WIND SHEAR TO STRENGTHEN TODAY WITH STRONGER SOUTHWEST WINDS ALOFT. MIXING MAY CAUSE A DROP OF DEWPOINTS SLIGHTLY...BUT THE MOISTURE BEING ADVECTED IN COULD COUNTER THIS AND EASILY SUPPORT HEAT INDEX VALUES AROUND 100-104F THIS AFTERNOON. SOME WEAK CONVERGENCE COULD BE ENOUGH TO TRIGGER SOME ISOLATED STORMS MAINLY ACROSS OUR SOUTHERN TIER OF COUNTIES UP INTO NW PA. THE LAKESHORE COUNTIES SHOULD REMAIN RAIN FREE FOR THE BETTER PART OF THE DAY. THE CONVECTION IS EXPECTED TO GET GOING MID DAY NORTH IN MI AND CANADA WHERE THE DYNAMICS WILL BE THE BEST. MODELS ARE INDICATING SOME SUBSIDENCE OVER MOST OF OUR AREA THIS AFTERNOON WHICH COULD LEAVE US WITH MOSTLY SUNNY SKIES EXCEPT THE MORE SOUTHERN COUNTIES. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... ALL EYES WILL BE ON THE CONVECTION ANTICIPATED TO OUR NORTH AND ANY OUTFLOWS THAT COULD SINK ACROSS THE LAKE AND TRIGGER STORMS THIS EVENING IN OUR NORTHERN COUNTIES. EXCLUDING THAT SCENARIO...THE BEST CHANCE FOR THUNDERSTORMS WON`T BE UNTIL 03-06Z AS THE FRONT SINKS SOUTH INTO OUR AREA. THE BOTTLED UP ENERGY IN PLACE OVER THE REGION WITH CAPES EXCEEDING 3K J/KG WILL BE REDUCED MARGINALLY OVERNIGHT...BUT NOT ENOUGH TO RULE OUT STRONG TO SEVERE STORMS. WITH UNIDIRECTIONAL WIND SHEAR...WITH A DECENT AMOUNT OF SPEED SHEAR...THE HIGHEST THREAT WILL BE STRONG STRAIGHT LINE WINDS. THE SLOW MOVING FRONT WILL PUSH INTO THE AREA DURING THE EARLY MORNING HOURS ON SATURDAY. THIS WILL PROVIDE A FOCUS FOR MORE CONVECTION ON SATURDAY...GRADUALLY CLEARING FROM NW TO SE DURING THE AFTERNOON. SPC HAS THE REGION OUTLOOKED FOR SLIGHT RISK OF SEVERE WEATHER FOR SATURDAY. THE STORM MOTIONS WILL BE SUFFICIENT TO KEEP THE FLOOD RISK LIMITED TO ONLY AREAS WHERE THERE MAY BE TRAINING. CONCERN HERE WILL BE WHERE THE FRONT OR OTHER BOUNDARIES HANG UP...OTHERWISE THE HIGHEST QPF LOOKS TO BE OVER NW PA. OVERALL LOOKING AT A 0.5" WIDESPREAD AVERAGE WITH LOCALLY HIGHER AMOUNTS. BEHIND FROPA A COOLER AND DRIER HIGH OUT OF CANADA WILL SLIDE IN FOR SUNDAY GIVING A NICE BREAK TO THE HOT HUMID WEATHER OF THE LAST WEEK. BY MONDAY AN UPPER LVL TROF WILL DEVELOP OVER THE OH VALLEY AND WE`LL SEE A RETURN OF MUGGY CONDITIONS. TEMPERATURES HOWEVER WILL REMAIN AT OR BELOW SEASONAL NORMALS AS THE THICKNESSES DROP. THE PRESENCE OF THE TROUGH AND INCREASED MOISTURE RETURN WILL UNFORTUNATELY PUT US BACK INTO A WETTER PATTERN...THOUGH NOTHING ORGANIZED AT THIS TIME. && .LONG TERM /TUESDAY THROUGH THURSDAY/... STILL PLENTY OF UNCERTAINTY IN THE FORECAST FOR TUESDAY THROUGH THURSDAY AS PIECES OF JET ENERGY MOVE THROUGH A TROUGH THAT WILL BE OVER THE GREAT LAKES REGION. FOR NOW HAVE SLIGHT CHANCE TO CHANCE POPS IN THE FORECAST FOR MOST OF THE REGION. TEMPERATURES TUESDAY THROUGH THURSDAY SHOULD BE VERY CLOSE TO SEASONAL AVERAGES. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... POP UP THUNDERSTORMS WILL SPREAD ACROSS MUCH OF NE OH/NW PA THIS AFTERNOON...INLAND FROM THE LAKE ERIE LAKE BREEZE. THE ODDS OF A DIRECT HIT ON AN AVIATION TERMINAL ARE PROBABLY 30-40 PERCENT AND WILL FORECAST "VICINITY" IN THE TAF THIS AFTERNOON EXCEPT AT KTOL AND KERI WHERE THEY SHOULD BE PROTECTED BY THE PROXIMITY TO LAKE ERIE. A LINE OF SHOWERS AND THUNDERSTORMS WILL SLIDE ACROSS LAKE ERIE TONIGHT AHEAD OF THE COLD FRONT. THE STORMS MAY BE WEAKENING BY THE EARLY MORNING HOURS BUT THERE IS A GOOD CHANCE OF MVFR CONDITIONS AND A CHANCE FOR IFR VISIBILITIES IN THE HEAVIER THUNDERSTORMS. MVFR STRATOCUMULUS CEILINGS WILL LIKELY DEVELOP AFTER THE SHOWERS/STORMS EARLY SATURDAY OR FIRST THING SATURDAY MORNING. CEILINGS WILL LIFT TO VFR SATURDAY AFTERNOON. NEW SHOWERS/STORMS MAY DEVELOP SATURDAY AFTERNOON FROM NEAR KYNG TO KCAK AND KMFD BUT NOT A LOT OF CONFIDENCE AND WILL LEAVE THEM OUT OF THE FORECAST FOR NOW. GUSTY WINDS THIS AFTERNOON WILL SETTLE TONIGHT AND SHIFT TO THE WEST SATURDAY MORNING AS THE COLD FRONT BEGINS TO SLIDE ACROSS THE AREA. .OUTLOOK...NON VFR IN PATCHY EARLY MORNING FOG. SHOWERS AND THUNDERSTORMS MAY ALSO CAUSE NON VFR CONDITIONS MONDAY THRU WEDNESDAY. && .MARINE... A COLD FRONT WILL MOVE INTO THE UPPER GREAT LAKES TODAY AS HIGH PRESSURE MOVES TO THE SOUTHEASTERN US. THIS WILL ALLOW A STRONGER PRESSURE GRADIENT TO DEVELOP OVER THE LAKE TODAY. SOUTHWEST WINDS OF 10 TO 20 KNOTS SHOULD BE ENOUGH TO BUILD WAVES TO 3 TO 5 FEET FROM WILLOWICK TO RIPLEY. THE LARGEST WAVES WILL LIKELY BE IN THE PA WATERS. SO WITH THAT SAID WE WILL HOIST A SMALL CRAFT ADVISORY THAT WILL REMAIN IN EFFECT THROUGH TONIGHT. THE COLD FRONT WILL MOVE SOUTHEAST ACROSS LAKE ERIE ON SATURDAY. HIGH PRESSURE WILL THEN BUILD ACROSS THE GREAT LAKES ON SUNDAY BEFORE SHIFTING EAST AND STAYING NORTH OF LAKE ERIE ON MONDAY. NORTHEAST WINDS WILL DEVELOP BY SUNDAY MORNING WITH CHOPPY CONDITIONS POSSIBLE FOR THE WESTERN HALF OF THE LAKE. WINDS SHOULD BECOME SOUTHERLY BY MONDAY AS WARM FRONT LIFTS ACROSS THE LAKE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR OHZ003-006>011- 013-017>023-027>033-036>038-047. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ147>149. && $$ SYNOPSIS...JAMISON NEAR TERM...JAMISON/TK SHORT TERM...JAMISON LONG TERM...MULLEN AVIATION...KOSARIK MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1002 AM EDT FRI JUL 19 2013 .SYNOPSIS... HOT AND HUMID AIRMASS OVER THE REGION WILL BREAK DOWN TONIGHT AS A COLD FRONT MOVES INTO THE REGION. STORMS WILL ACCOMPANY THE FRONT AS IT MOVES THROUGH THE AREA ON SATURDAY. COOLER AND DRIER WEATHER ON TAP FOR SUNDAY...BUT THE HUMIDITY WILL RETURN EARLY NEXT WEEK. TEMPERATURES WILL BE MORE COMFORTABLE WITH HIGHS AT OR SLIGHTLY BELOW NORMAL THROUGH MOST OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...MADE MINOR ADJUSTMENTS FOR THE NEXT SEVERAL DAYS. FOR TODAY ADDED A SLIGHT CHANCE TO THE NORTHWEST COUNTIES WHERE LIKE THE PAST FEW DAYS THE HRRR SHOWED AFTERNOON DEVELOPMENT. TEMPERATURES OVERNIGHT REMAINED HIGH IN THE MID 70S...WHICH WILL PROVIDE A WARM START FOR HEAT ADVISORY CONDITIONS LATER TODAY. LOOK FOR SCATTERED CLOUDS DEVELOPING THIS AFTERNOON...BUT NOT ENOUGH COVERAGE TO KEEP TEMPERATURES FROM RETURNING TO THE LOWER 90S...AND IN SOME W SITES IN THE MID 90S. EXPECT SOME LOW LEVEL WIND SHEAR TO STRENGTHEN TODAY WITH STRONGER SOUTHWEST WINDS ALOFT. MIXING MAY CAUSE A DROP OF DEWPOINTS SLIGHTLY...BUT THE MOISTURE BEING ADVECTED IN COULD COUNTER THIS AND EASILY SUPPORT HEAT INDEX VALUES AROUND 100-104F THIS AFTERNOON. SOME WEAK CONVERGENCE COULD BE ENOUGH TO TRIGGER SOME ISOLATED STORMS MAINLY ACROSS OUR SOUTHERN TIER OF COUNTIES UP INTO NW PA. THE LAKESHORE COUNTIES SHOULD REMAIN RAIN FREE FOR THE BETTER PART OF THE DAY. THE CONVECTION IS EXPECTED TO GET GOING MID DAY NORTH IN MI AND CANADA WHERE THE DYNAMICS WILL BE THE BEST. MODELS ARE INDICATING SOME SUBSIDENCE OVER MOST OF OUR AREA THIS AFTERNOON WHICH COULD LEAVE US WITH MOSTLY SUNNY SKIES EXCEPT THE MORE SOUTHERN COUNTIES. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... ALL EYES WILL BE ON THE CONVECTION ANTICIPATED TO OUR NORTH AND ANY OUTFLOWS THAT COULD SINK ACROSS THE LAKE AND TRIGGER STORMS THIS EVENING IN OUR NORTHERN COUNTIES. EXCLUDING THAT SCENARIO...THE BEST CHANCE FOR THUNDERSTORMS WON`T BE UNTIL 03-06Z AS THE FRONT SINKS SOUTH INTO OUR AREA. THE BOTTLED UP ENERGY IN PLACE OVER THE REGION WITH CAPES EXCEEDING 3K J/KG WILL BE REDUCED MARGINALLY OVERNIGHT...BUT NOT ENOUGH TO RULE OUT STRONG TO SEVERE STORMS. WITH UNIDIRECTIONAL WIND SHEAR...WITH A DECENT AMOUNT OF SPEED SHEAR...THE HIGHEST THREAT WILL BE STRONG STRAIGHT LINE WINDS. THE SLOW MOVING FRONT WILL PUSH INTO THE AREA DURING THE EARLY MORNING HOURS ON SATURDAY. THIS WILL PROVIDE A FOCUS FOR MORE CONVECTION ON SATURDAY...GRADUALLY CLEARING FROM NW TO SE DURING THE AFTERNOON. SPC HAS THE REGION OUTLOOKED FOR SLIGHT RISK OF SEVERE WEATHER FOR SATURDAY. THE STORM MOTIONS WILL BE SUFFICIENT TO KEEP THE FLOOD RISK LIMITED TO ONLY AREAS WHERE THERE MAY BE TRAINING. CONCERN HERE WILL BE WHERE THE FRONT OR OTHER BOUNDARIES HANG UP...OTHERWISE THE HIGHEST QPF LOOKS TO BE OVER NW PA. OVERALL LOOKING AT A 0.5" WIDESPREAD AVERAGE WITH LOCALLY HIGHER AMOUNTS. BEHIND FROPA A COOLER AND DRIER HIGH OUT OF CANADA WILL SLIDE IN FOR SUNDAY GIVING A NICE BREAK TO THE HOT HUMID WEATHER OF THE LAST WEEK. BY MONDAY AN UPPER LVL TROF WILL DEVELOP OVER THE OH VALLEY AND WE`LL SEE A RETURN OF MUGGY CONDITIONS. TEMPERATURES HOWEVER WILL REMAIN AT OR BELOW SEASONAL NORMALS AS THE THICKNESSES DROP. THE PRESENCE OF THE TROUGH AND INCREASED MOISTURE RETURN WILL UNFORTUNATELY PUT US BACK INTO A WETTER PATTERN...THOUGH NOTHING ORGANIZED AT THIS TIME. && .LONG TERM /TUESDAY THROUGH THURSDAY/... STILL PLENTY OF UNCERTAINTY IN THE FORECAST FOR TUESDAY THROUGH THURSDAY AS PIECES OF JET ENERGY MOVE THROUGH A TROUGH THAT WILL BE OVER THE GREAT LAKES REGION. FOR NOW HAVE SLIGHT CHANCE TO CHANCE POPS IN THE FORECAST FOR MOST OF THE REGION. TEMPERATURES TUESDAY THROUGH THURSDAY SHOULD BE VERY CLOSE TO SEASONAL AVERAGES. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... PATCHY MORNING MVFR FOG HAS OCCURRED ONCE AGAIN FOR INLAND TAF SITES BUT WILL QUICKLY BURN OFF. OTHERWISE THERE WILL BE VFR CONDITIONS WITH AFTERNOON CUMULUS. SOUTHWESTERLY WINDS WILL BE STRONGER TODAY WITH GUSTS AROUND 20 KNOTS LIKELY. THE STRONGEST WINDS WILL LIKELY BE ACROSS NW OHIO INCLUDING KTOL AND KFDY WITH GUSTS AROUND 25 KNOTS. CANT COMPLETELY RULE OUT SOME ISOLATED CONVECTION OVER THE SOUTHERN TIER OF NY THAT MAY BUILD BACK INTO PORTIONS OF NW PA AND SOUTH OF A LINE FROM KFDY TO KYNG. WE WILL THEN AWAIT THE ARRIVAL OF THUNDERSTORMS AFTER SUNSET. MOST OF THEM WILL LIKELY BE AFTER 03Z AND GRADUALLY SAG SOUTH AND EAST WITH A COLD FRONT. SOME OF THESE STORMS WILL BE CAPABLE OF STRONG WINDS. .OUTLOOK...NON VFR IN PATCHY EARLY MORNING FOG. SHOWERS AND THUNDERSTORMS MAY ALSO CAUSE NON VFR CONDITIONS SATURDAY AND TUESDAY. && .MARINE... A COLD FRONT WILL MOVE INTO THE UPPER GREAT LAKES TODAY AS HIGH PRESSURE MOVES TO THE SOUTHEASTERN US. THIS WILL ALLOW A STRONGER PRESSURE GRADIENT TO DEVELOP OVER THE LAKE TODAY. SOUTHWEST WINDS OF 10 TO 20 KNOTS SHOULD BE ENOUGH TO BUILD WAVES TO 3 TO 5 FEET FROM WILLOWICK TO RIPLEY. THE LARGEST WAVES WILL LIKELY BE IN THE PA WATERS. SO WITH THAT SAID WE WILL HOIST A SMALL CRAFT ADVISORY THAT WILL REMAIN IN EFFECT THROUGH TONIGHT. THE COLD FRONT WILL MOVE SOUTHEAST ACROSS LAKE ERIE ON SATURDAY. HIGH PRESSURE WILL THEN BUILD ACROSS THE GREAT LAKES ON SUNDAY BEFORE SHIFTING EAST AND STAYING NORTH OF LAKE ERIE ON MONDAY. NORTHEAST WINDS WILL DEVELOP BY SUNDAY MORNING WITH CHOPPY CONDITIONS POSSIBLE FOR THE WESTERN HALF OF THE LAKE. WINDS SHOULD BECOME SOUTHERLY BY MONDAY AS WARM FRONT LIFTS ACROSS THE LAKE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR OHZ003-006>011-013-017>023-027>033-036>038- 047. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR LEZ147>149. && $$ SYNOPSIS...JAMISON NEAR TERM...JAMISON/TK SHORT TERM...JAMISON LONG TERM...MULLEN AVIATION...MULLEN MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
152 PM EDT FRI JUL 19 2013 .SYNOPSIS... THE SUBTROPICAL RIDGE OVER THE EASTERN UNITED STATES WILL WEAKEN AND SHIFT EASTWARD...YIELDING TO A VIGOROUS NORTHERN STREAM SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES INTO THE NEW ENGLAND. IT WILL BE UNSEASONABLY WARM UNTIL THE ASSOCIATED COLD FRONTAL PASSAGE LATER SATURDAY. THE COLD FRONT COULD TRIGGER SOME SEVERE THUNDERSTORMS. A BROAD UPPER LEVEL TROUGH SHOULD BUILD OVER THE REGION FROM SUNDAY INTO NEXT WEEK. THIS PATTERN WILL FEATURE A RETURN TO NEAR NORMAL TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... 17Z...TSTMS ARE DEVELOPING IN AREAS WHERE THE MESO MDLS HAD PROJECTED - ON THE ELEVATED TERRAIN FROM NRN WV INTO SW PA AND DOWNWIND OF LAKE ERIE. A FEW ISOLD CELLS ALSO FIRED OVER THE SE PIEDMONT FROM NEAR MDT-LNS TO JUST NORTH OF RDG. STORM NEAR LNS GREW QUICKLY TAPPING ABUNDANT CAPE (90/75 AT 16Z) WITH TOPS OVER 40KFT. THE LATEST RAPID-REFRESH HRRR SUGGEST A LINE OF STORMS MAY DOWNWIND OF LAKE ERIE FROM NRN OH ACRS NW PA LATE THIS AFTN. AGAIN MADE VERY MINOR CHANGES TO THE GOING FCST OF ISOLD TO SCT TSTMS. 17-18Z HX VALUES MAY PUSH 105F AT LNS AND MDT BUT WILL CONTINUE WITH HEAT ADVY. PREVIOUS DISCUSSION... 14-15Z...VISIBLE SATL LOOPS SHOW CU FIELD GOING UP ALONG ON THE WRN AND CNTRL RIDGES...PARALLEL TO THE LLVL FLOW INDICATING BLYR DESTABILIZATION. 14Z RUC ML CAPES ARE RUNNING BTWN 2-2.5K J/KG PER SPC MESO PAGE. LATEST OBS STILL SHOW SOME 6-7SM HZ WITH SFC DEWPOINTS IN THE LOW 70S. TEMPS SHOULD REACH THE LOW 90S IN THE LWR SUSQ VLY BY 15Z WITH HEAT INDEXES APPROACHING 100F. THE MAIN FCST CHALLENGE FOR TODAY CONTINUES TO BE FOCUSED ON THE DEVELOPMENT/PLACEMENT OF DIURNAL CONVECTION. WITH AFTN TEMPS IN THE UPPER 80S TO MID 90S AND SFC DEWPTS BTWN 65-70F...CAPES WILL BE ROBUST AND EASILY SUPPORT UPDRAFTS. QUESTION REMAINS AS TO THE EVOLUTION OF STORMS GIVEN NEBULOUS FORCING AND WARM 700MB TEMPS. RAPID-REFRESH MESO MDL DATA IS STILL SHOWING THE GREATEST CVRG OF TSTMS IN WRN/SWRN PA INTO WV. THIS MAY BE DUE TO A WK SHORTWAVE ROTATING FROM KY INTO THE UPPER OH VLY ON THE NW PERIPHERY OF RETREATING UPPER RIDGE. THE TERRAIN WILL ALSO ACT TO ENHANCE LIFT. SOME CONVECTION IS ALSO PSBL NEAR THE LAKESHORE BOUNDARY OVER THE NW MTNS. OVERALL...EXPECT ISOLD TO WDLY SCT TSTMS AS WE GET LATER IN THE DAY. THE ENVIRONMENT SHOULD FAVOR MAINLY NON-SVR MULTI-CELL STORMS GIVEN HIGH CAPE AND RELATIVELY WEAK 0-6KM SHEAR. A HEAT ADVISORY REMAINS IN EFFECT FOR THE S-CENTRAL MTNS AND SUSQ VLY UNTL 8PM. HEAT INDEXES/APPARENT TEMPERATURES ARE FCST TO REACH THE 100 TO 104F RANGE...RESULTING IN AN ELEVATED RISK OF HEAT- RELATED ILLNESS ESPECIALLY THOSE WITHOUT AC OR OUTDOORS FOR AN EXTENDED PERIOD. AFTN/EVE STORMS SHOULD WEAKEN INTO TONIGHT WITH THE LOSS OF HEATING. IT WILL BE A WARM HUMID/MUGGY OVERNIGHT WITH INCREASED SOUTHERLY FLOW AHEAD OF THE APPROACHING FRONTAL SYSTEM - WHICH SHOULD REACH THE ST. LAWRENCE VLY AND LWR LKS REGIONS BY DAYBREAK SATURDAY. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... BROAD CYCLONIC FLOW ALOFT ASSOCIATED WITH AN UPPER LEVEL TROUGH WILL SPREAD SEWD FROM THE GREAT LAKES REGION ACRS THE OH VLY INTO THE NRN APPLCHNS. A 60-75KT MID-LVL JET WILL MOVE THROUGH THE SE- SIDE OF THE TROUGH ACRS QUEBEC. A COLD FRONT...CURRENTLY CROSSING CENTRAL WI AND N-CENTRL LWR MI...SHOULD BE ACTIVE AT THE START OF THE PERIOD WITH SHOWERS AND STORMS INVOF THE ST.LAWRENCE VLY SWWD INTO THE LWR/ERN LAKES. AS THE COLD FRONT CONTINUES TO PUSH SEWD INTO PA BY SAT AFTN...EXPECT CONVECTION TO EXPAND IN COVERAGE AND INTENSITY WHICH WILL COINCIDE WITH SFC HEATING IN THE WARM SECTOR. THE PRE-FRONTAL ENVIRONMENT WILL BE CHARACTERIZED BY MODERATE INSTABILITY AND 30+ KTS OF 0-6KM SHEAR...WHICH SHOULD SUPPORT ORGANIZED STORM STRUCTURES. THE UNIDIRECTIONAL WIND PROFILES SUGGEST THE PRIMARY SEVERE STORM THREAT WILL BE DMGG WINDS WITH SOME LARGE HAIL ALSO POSSIBLE WHERE STORMS CAN INGEST THE HIGH CAPES. SPC HAS MAINTAINED A SLGT RISK OUTLOOK FOR SEVERAL DAYS NOW AND EXPECT THIS TO PAN-OUT DURING THE DAY TOMORROW. THE WILD CARD MAY BE THE DEVELOPMENT OF AN MCS WHICH COULD COMPLICATE THINGS PRIOR TO FROPA. SREF/GEFS PWAT FCSTS SUGGEST THE COLD FRONT WILL CLEAR THE NRN ZONES BY 00Z BUT LINGER OVER SRN PA INTO SUNDAY MORNING. THEREFORE KEPT LOW POPS ACRS THE SRN 1/2 TO 1/3 OF THE CWA LATE TONIGHT. AS DRIER AIR ARRIVES BEHIND THE FRONT...LOOK FOR A COOLER...MORE COMFORTABLE OVERNIGHT PERIOD OVER THE N-CNTRL MTNS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... SUNDAY SHOULD BE A POST FRONTAL DAY WITH PW VALUES NEAR TO SLIGHTLY BELOW NORMAL. THE LOWER TROPOSPHERIC TEMPERATURES WILL BE NEAR NORMAL TOO. THE CHANCE TO SHOWERS SHOULD BE LOW PERHAPS BEST CHANCE IN SOUTHERNMOST AREAS CLOSE TO THE FRONTAL BOUNDARY. OVERALL...SUNDAY IS LOOKING LIKE A VERY PLEASANT DAY FOR MOST AREAS AS A WEAK AREA OF HIGH PRESSURE WILL BE OVER THE REGION. THE LOWER HUMIDITY AND LOWER TEMPERATURES SHOULD BE WELCOME RELIEF. THE LOW-LEVEL FRONTAL BOUNDARY DOES NOT PUSH TOO FAR TO OUR SOUTH. THUS AS ANOTHER WAVE APPROACHES FROM THE WEST IT WILL LIKELY PULL SOME OF THE MOISTURE BACK INTO THE REGION LATE MONDAY INTO TUESDAY INCREASING THE CHANCE OF SHOWERS AND THUNDERSTORMS. THE NORTHWESTERLY FLOW WILL LIKELY PUSH A FRONT THROUGH THE REGION AROUND MID-WEEK. THIS COULD INCREASE THE CHANCE OF SHOWERS AND THUNDERSTORMS...MOST LIKELY ON WEDNESDAY. BEHIND THIS SECOND FRONT THE PW VALUES DROP TO BELOW NORMAL...SHOULD BE VERY COMFORTABLE THURSDAY AND FRIDAY BEHIND THIS FRONT SHOULD THESE FORECAST PROVE CLOSE TO CORRECT. OVERALL...THE MODELS AND ENSEMBLES ALL SHOW A TROUGH OVER THE EASTERN USA MOST OF THE COMING WEEK IMPLYING COOLER AND RELATIVELY DRIER WEATHER. BY MID-WEEK THE HEAT WAVE OF MID-JULY 2013 SHOULD BE A FAINT MEMORY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR CUMULUS WILL CONTINUE TO BUILD THRU THE AFTN WITH VISBYS IN THE 6-8SM RANGE IN HZ DUE TO VERY MOIST BLYR /DEWPOINTS IN THE UPPER 60S TO LOW 70S/. INCREASING INSTABILITY SHOULD COMBINE WITH THE TERRAIN TO PROMOTE ISOLD TO SCT TSTM ACTIVITY WITH INITIATION IN THE 17-20Z TIMEFRAME. WILL CONTINUE TO SHOW VCTS AND CB/S IN THE TAFS GIVEN UNCERTAINTY IN EXACT LOCATION OF STORMS. W/SW LLVL FLOW AHEAD OF APPROACHING COLD FRONT SHOULD LIMIT FOG/ST FORMATION LATE TONIGHT...ESPECIALLY OVER THE WRN AREAS. ERN TAFS HAVE A BETTER SHOT A GOING CLR/CALM SO COULD SEE SOME LCL RESTRICTIONS BY DAYBREAK SATURDAY. THE COLD FRONT WILL CROSS THE REGION LATER SATURDAY AND TRIGGER SCT STG TO SVR STORMS. THE WND SHIFT SHOULD OCCUR FROM NW-SE BY SAT NIGHT. OUTLOOK... SAT...VFR. PM TSTM IMPACTS. SOME STORMS MAY BE SVR. SUN...MVFR TO VFR. SHOWERS/ISOLD TSRA PSBL SOUTH. MON...VFR. TUES...VFR WITH PM SHOWERS/THUNDERSTORMS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ019-026>028- 035>037-041-042-045-046-049>053-056>059-063>066. && $$ SYNOPSIS...GRUMM/STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...GRUMM/MARTIN AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1259 PM EDT FRI JUL 19 2013 .SYNOPSIS... THE SUBTROPICAL RIDGE OVER THE EASTERN UNITED STATES WILL WEAKEN AND SHIFT EASTWARD...YIELDING TO A VIGOROUS NORTHERN STREAM SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES INTO THE NEW ENGLAND. IT WILL BE UNSEASONABLY WARM UNTIL THE ASSOCIATED COLD FRONTAL PASSAGE LATER SATURDAY. THE COLD FRONT COULD TRIGGER SOME SEVERE THUNDERSTORMS. A BROAD UPPER LEVEL TROUGH SHOULD BUILD OVER THE REGION FROM SUNDAY INTO NEXT WEEK. THIS PATTERN WILL FEATURE A RETURN TO NEAR NORMAL TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... 17Z...TSTMS ARE DEVELOPING IN AREAS WHERE THE MESO MDLS HAD PROJECTED - ON THE ELEVATED TERRAIN FROM NRN WV INTO SW PA AND DOWNWIND OF LAKE ERIE. A FEW ISOLD CELLS ALSO FIRED OVER THE SE PIEDMONT FROM NEAR MDT-LNS TO JUST NORTH OF RDG. STORM NEAR LNS GREW QUICKLY TAPPING ABUNDANT CAPE (90/75 AT 16Z) WITH TOPS OVER 40KFT. THE LATEST RAPID-REFRESH HRRR SUGGEST A LINE OF STORMS MAY DOWNWIND OF LAKE ERIE FROM NRN OH ACRS NW PA LATE THIS AFTN. AGAIN MADE VERY MINOR CHANGES TO THE GOING FCST OF ISOLD TO SCT TSTMS. 17-18Z HX VALUES MAY PUSH 105F AT LNS AND MDT BUT WILL CONTINUE WITH HEAT ADVY. PREVIOUS DISCUSSION... 14-15Z...VISIBLE SATL LOOPS SHOW CU FIELD GOING UP ALONG ON THE WRN AND CNTRL RIDGES...PARALLEL TO THE LLVL FLOW INDICATING BLYR DESTABILIZATION. 14Z RUC ML CAPES ARE RUNNING BTWN 2-2.5K J/KG PER SPC MESO PAGE. LATEST OBS STILL SHOW SOME 6-7SM HZ WITH SFC DEWPOINTS IN THE LOW 70S. TEMPS SHOULD REACH THE LOW 90S IN THE LWR SUSQ VLY BY 15Z WITH HEAT INDEXES APPROACHING 100F. THE MAIN FCST CHALLENGE FOR TODAY CONTINUES TO BE FOCUSED ON THE DEVELOPMENT/PLACEMENT OF DIURNAL CONVECTION. WITH AFTN TEMPS IN THE UPPER 80S TO MID 90S AND SFC DEWPTS BTWN 65-70F...CAPES WILL BE ROBUST AND EASILY SUPPORT UPDRAFTS. QUESTION REMAINS AS TO THE EVOLUTION OF STORMS GIVEN NEBULOUS FORCING AND WARM 700MB TEMPS. RAPID-REFRESH MESO MDL DATA IS STILL SHOWING THE GREATEST CVRG OF TSTMS IN WRN/SWRN PA INTO WV. THIS MAY BE DUE TO A WK SHORTWAVE ROTATING FROM KY INTO THE UPPER OH VLY ON THE NW PERIPHERY OF RETREATING UPPER RIDGE. THE TERRAIN WILL ALSO ACT TO ENHANCE LIFT. SOME CONVECTION IS ALSO PSBL NEAR THE LAKESHORE BOUNDARY OVER THE NW MTNS. OVERALL...EXPECT ISOLD TO WDLY SCT TSTMS AS WE GET LATER IN THE DAY. THE ENVIRONMENT SHOULD FAVOR MAINLY NON-SVR MULTI-CELL STORMS GIVEN HIGH CAPE AND RELATIVELY WEAK 0-6KM SHEAR. A HEAT ADVISORY REMAINS IN EFFECT FOR THE S-CENTRAL MTNS AND SUSQ VLY UNTL 8PM. HEAT INDEXES/APPARENT TEMPERATURES ARE FCST TO REACH THE 100 TO 104F RANGE...RESULTING IN AN ELEVATED RISK OF HEAT- RELATED ILLNESS ESPECIALLY THOSE WITHOUT AC OR OUTDOORS FOR AN EXTENDED PERIOD. AFTN/EVE STORMS SHOULD WEAKEN INTO TONIGHT WITH THE LOSS OF HEATING. IT WILL BE A WARM HUMID/MUGGY OVERNIGHT WITH INCREASED SOUTHERLY FLOW AHEAD OF THE APPROACHING FRONTAL SYSTEM - WHICH SHOULD REACH THE ST. LAWRENCE VLY AND LWR LKS REGIONS BY DAYBREAK SATURDAY. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... THE CLOUDS WITH THE FRONT SHOULD KEEP IT A BIT COOLER SATURDAY ESPECIALLY IN THE NORTHWESTERN AREAS. THE STRONG SOUTHWESTERLY FLOW...HIGH PRECIPITABLE WATER VALUES AND RELATIVELY HIGH CAPE IMPLY THAT THERE SHOULD BE THUNDERSTORMS SATURDAY FROM LATE MORNING IN THE WEST TO LATER AFTERNOON IN THE SOUTHEAST. SOME OF THESE STORMS COULD BE STRONG TO SEVERE. NEARLY ALL OF OUR AREA IS IN SLIGHT RISK FOR SEVERE THUNDERSTORMS SATURDAY. THERE IS SOME MODESTLY STRONG MOISTURE FLUX AT 850 HPA IMPLYING GOOD LIFT MOVING ACROSS THE STATE FROM ABOUT 15Z TO 00Z. MOST MODELS IMPLY THE DEEP MOISTURE PLUME IS PUSHED TO OUR EAST SATURDAY EVENING. DRIER AIR MOVES IN LATE EVENING WITH COOLER AIR BEHIND IT. SHOULD BECOME QUITE COMFORTABLE OVERNIGHT AND NOTICEABLY COOLER LOWS ON SUNDAY MORNING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... SUNDAY SHOULD BE A POST FRONTAL DAY WITH PW VALUES NEAR TO SLIGHTLY BELOW NORMAL. THE LOWER TROPOSPHERIC TEMPERATURES WILL BE NEAR NORMAL TOO. THE CHANCE TO SHOWERS SHOULD BE LOW PERHAPS BEST CHANCE IN SOUTHERNMOST AREAS CLOSE TO THE FRONTAL BOUNDARY. OVERALL...SUNDAY IS LOOKING LIKE A VERY PLEASANT DAY FOR MOST AREAS AS A WEAK AREA OF HIGH PRESSURE WILL BE OVER THE REGION. THE LOWER HUMIDITY AND LOWER TEMPERATURES SHOULD BE WELCOME RELIEF. THE LOW-LEVEL FRONTAL BOUNDARY DOES NOT PUSH TOO FAR TO OUR SOUTH. THUS AS ANOTHER WAVE APPROACHES FROM THE WEST IT WILL LIKELY PULL SOME OF THE MOISTURE BACK INTO THE REGION LATE MONDAY INTO TUESDAY INCREASING THE CHANCE OF SHOWERS AND THUNDERSTORMS. THE NORTHWESTERLY FLOW WILL LIKELY PUSH A FRONT THROUGH THE REGION AROUND MID-WEEK. THIS COULD INCREASE THE CHANCE OF SHOWERS AND THUNDERSTORMS...MOST LIKELY ON WEDNESDAY. BEHIND THIS SECOND FRONT THE PW VALUES DROP TO BELOW NORMAL...SHOULD BE VERY COMFORTABLE THURSDAY AND FRIDAY BEHIND THIS FRONT SHOULD THESE FORECAST PROVE CLOSE TO CORRECT. OVERALL...THE MODELS AND ENSEMBLES ALL SHOW A TROUGH OVER THE EASTERN USA MOST OF THE COMING WEEK IMPLYING COOLER AND RELATIVELY DRIER WEATHER. BY MID-WEEK THE HEAT WAVE OF MID-JULY 2013 SHOULD BE A FAINT MEMORY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR CUMULUS WILL CONTINUE TO BUILD THRU THE AFTN WITH VISBYS IN THE 6-8SM RANGE IN HZ DUE TO VERY MOIST BLYR /DEWPOINTS IN THE UPPER 60S TO LOW 70S/. INCREASING INSTABILITY SHOULD COMBINE WITH THE TERRAIN TO PROMOTE ISOLD TO SCT TSTM ACTIVITY WITH INITIATION IN THE 17-20Z TIMEFRAME. WILL CONTINUE TO SHOW VCTS AND CB/S IN THE TAFS GIVEN UNCERTAINTY IN EXACT LOCATION OF STORMS. W/SW LLVL FLOW AHEAD OF APPROACHING COLD FRONT SHOULD LIMIT FOG/ST FORMATION LATE TONIGHT...ESPECIALLY OVER THE WRN AREAS. ERN TAFS HAVE A BETTER SHOT A GOING CLR/CALM SO COULD SEE SOME LCL RESTRICTIONS BY DAYBREAK SATURDAY. THE COLD FRONT WILL CROSS THE REGION LATER SATURDAY AND TRIGGER SCT STG TO SVR STORMS. THE WND SHIFT SHOULD OCCUR FROM NW-SE BY SAT NIGHT. OUTLOOK... SAT...VFR. PM TSTM IMPACTS. SOME STORMS MAY BE SVR. SUN...MVFR TO VFR. SHOWERS/ISOLD TSRA PSBL SOUTH. MON...VFR. TUES...VFR WITH PM SHOWERS/THUNDERSTORMS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ019-026>028- 035>037-041-042-045-046-049>053-056>059-063>066. && $$ SYNOPSIS...GRUMM/STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...GRUMM/MARTIN AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1119 AM EDT FRI JUL 19 2013 .SYNOPSIS... THE SUBTROPICAL RIDGE OVER THE EASTERN UNITED STATES WILL BEGIN ITS SLOW EROSION OVER THE NEXT 2 DAYS. A VIGOROUS NORTHERN STREAM WAVE SHOULD LOWER THE 500 HPA HEIGHTS AND PUSH A COLD FRONT INTO THE REGION SATURDAY. IT WILL BE UNSEASONABLY WARM UNTIL THE FRONTAL PASSAGE AND THE FRONT COULD TRIGGER SOME STRONG THUNDERSTORMS. THE 500 HPA TROUGH SHOULD BUILD OVER THE REGION SUNDAY INTO NEXT WEEK. IT WILL BE SIGNIFICANTLY COOLER AND DRIER SUNDAY AND INTO THE COMING WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... 14-15Z...VISIBLE SATL LOOPS SHOW CU FIELD GOING UP ALONG ON THE WRN AND CNTRL RIDGES...PARALLEL TO THE LLVL FLOW INDICATING BLYR DESTABILIZATION. 14Z RUC ML CAPES ARE RUNNING BTWN 2-2.5K J/KG PER SPC MESO PAGE. LATEST OBS STILL SHOW SOME 6-7SM HZ WITH SFC DEWPOINTS IN THE LOW 70S. TEMPS SHOULD REACH THE LOW 90S IN THE LWR SUSQ VLY BY 15Z WITH HEAT INDEXES APPROACHING 100F. THE MAIN FCST CHALLENGE FOR TODAY CONTINUES TO BE FOCUSED ON THE DEVELOPMENT/PLACEMENT OF DIURNAL CONVECTION. WITH AFTN TEMPS IN THE UPPER 80S TO MID 90S AND SFC DEWPTS BTWN 65-70F...CAPES WILL BE ROBUST AND EASILY SUPPORT UPDRAFTS. QUESTION REMAINS AS TO THE EVOLUTION OF STORMS GIVEN NEBULOUS FORCING AND WARM 700MB TEMPS. RAPID-REFRESH MESO MDL DATA IS STILL SHOWING THE GREATEST CVRG OF TSTMS IN WRN/SWRN PA INTO WV. THIS MAY BE DUE TO A WK SHORTWAVE ROTATING FROM KY INTO THE UPPER OH VLY ON THE NW PERIPHERY OF RETREATING UPPER RIDGE. THE TERRAIN WILL ALSO ACT TO ENHANCE LIFT. SOME CONVECTION IS ALSO PSBL NEAR THE LAKESHORE BOUNDARY OVER THE NW MTNS. OVERALL...EXPECT ISOLD TO WDLY SCT TSTMS AS WE GET LATER IN THE DAY. THE ENVIRONMENT SHOULD FAVOR MAINLY NON-SVR MULTI-CELL STORMS GIVEN HIGH CAPE AND RELATIVELY WEAK 0-6KM SHEAR. A HEAT ADVISORY REMAINS IN EFFECT FOR THE S-CENTRAL MTNS AND SUSQ VLY UNTL 8PM. HEAT INDEXES/APPARENT TEMPERATURES ARE FCST TO REACH THE 100 TO 104F RANGE...RESULTING IN AN ELEVATED RISK OF HEAT- RELATED ILLNESS ESPECIALLY THOSE WITHOUT AC OR OUTDOORS FOR AN EXTENDED PERIOD. AFTN/EVE STORMS SHOULD WEAKEN INTO TONIGHT WITH THE LOSS OF HEATING. IT WILL BE A WARM HUMID/MUGGY OVERNIGHT WITH INCREASED SOUTHERLY FLOW AHEAD OF THE APPROACHING FRONTAL SYSTEM - WHICH SHOULD REACH THE ST. LAWRENCE VLY AND LWR LKS REGIONS BY DAYBREAK SATURDAY. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... THE CLOUDS WITH THE FRONT SHOULD KEEP IT A BIT COOLER SATURDAY ESPECIALLY IN THE NORTHWESTERN AREAS. THE STRONG SOUTHWESTERLY FLOW...HIGH PRECIPITABLE WATER VALUES AND RELATIVELY HIGH CAPE IMPLY THAT THERE SHOULD BE THUNDERSTORMS SATURDAY FROM LATE MORNING IN THE WEST TO LATER AFTERNOON IN THE SOUTHEAST. SOME OF THESE STORMS COULD BE STRONG TO SEVERE. NEARLY ALL OF OUR AREA IS IN SLIGHT RISK FOR SEVERE THUNDERSTORMS SATURDAY. THERE IS SOME MODESTLY STRONG MOISTURE FLUX AT 850 HPA IMPLYING GOOD LIFT MOVING ACROSS THE STATE FROM ABOUT 15Z TO 00Z. MOST MODELS IMPLY THE DEEP MOISTURE PLUME IS PUSHED TO OUR EAST SATURDAY EVENING. DRIER AIR MOVES IN LATE EVENING WITH COOLER AIR BEHIND IT. SHOULD BECOME QUITE COMFORTABLE OVERNIGHT AND NOTICEABLY COOLER LOWS ON SUNDAY MORNING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... SUNDAY SHOULD BE A POST FRONTAL DAY WITH PW VALUES NEAR TO SLIGHTLY BELOW NORMAL. THE LOWER TROPOSPHERIC TEMPERATURES WILL BE NEAR NORMAL TOO. THE CHANCE TO SHOWERS SHOULD BE LOW PERHAPS BEST CHANCE IN SOUTHERNMOST AREAS CLOSE TO THE FRONTAL BOUNDARY. OVERALL...SUNDAY IS LOOKING LIKE A VERY PLEASANT DAY FOR MOST AREAS AS A WEAK AREA OF HIGH PRESSURE WILL BE OVER THE REGION. THE LOWER HUMIDITY AND LOWER TEMPERATURES SHOULD BE WELCOME RELIEF. THE LOW-LEVEL FRONTAL BOUNDARY DOES NOT PUSH TOO FAR TO OUR SOUTH. THUS AS ANOTHER WAVE APPROACHES FROM THE WEST IT WILL LIKELY PULL SOME OF THE MOISTURE BACK INTO THE REGION LATE MONDAY INTO TUESDAY INCREASING THE CHANCE OF SHOWERS AND THUNDERSTORMS. THE NORTHWESTERLY FLOW WILL LIKELY PUSH A FRONT THROUGH THE REGION AROUND MID-WEEK. THIS COULD INCREASE THE CHANCE OF SHOWERS AND THUNDERSTORMS...MOST LIKELY ON WEDNESDAY. BEHIND THIS SECOND FRONT THE PW VALUES DROP TO BELOW NORMAL...SHOULD BE VERY COMFORTABLE THURSDAY AND FRIDAY BEHIND THIS FRONT SHOULD THESE FORECAST PROVE CLOSE TO CORRECT. OVERALL...THE MODELS AND ENSEMBLES ALL SHOW A TROUGH OVER THE EASTERN USA MOST OF THE COMING WEEK IMPLYING COOLER AND RELATIVELY DRIER WEATHER. BY MID-WEEK THE HEAT WAVE OF MID-JULY 2013 SHOULD BE A FAINT MEMORY. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... VFR CUMULUS WILL CONTINUE TO BUILD THRU THE AFTN WITH VISBYS IN THE 6-8SM RANGE IN HZ DUE TO VERY MOIST BLYR /DEWPOINTS IN THE UPPER 60S TO LOW 70S/. INCREASING INSTABILITY SHOULD COMBINE WITH THE TERRAIN TO PROMOTE ISOLD TO SCT TSTM ACTIVITY WITH INITIATION IN THE 17-20Z TIMEFRAME. WILL CONTINUE TO SHOW VCTS AND CB/S IN THE TAFS GIVEN UNCERTAINTY IN EXACT LOCATION OF STORMS. W/SW LLVL FLOW AHEAD OF APPROACHING COLD FRONT SHOULD LIMIT FOG/ST FORMATION LATE TONIGHT...ESPECIALLY OVER THE WRN AREAS. ERN TAFS HAVE A BETTER SHOT A GOING CLR/CALM SO COULD SEE SOME LCL RESTRICTIONS BY DAYBREAK SATURDAY. THE COLD FRONT WILL CROSS THE REGION LATER SATURDAY AND TRIGGER SCT STG TO SVR STORMS. THE WND SHIFT SHOULD OCCUR FROM NW-SE BY SAT NIGHT. OUTLOOK... SAT...VFR. PM TSTM IMPACTS. SOME STORMS MAY BE SVR. SUN...MVFR TO VFR. SHOWERS/ISOLD TSRA PSBL SOUTH. MON...VFR. TUES...VFR WITH PM SHOWERS/THUNDERSTORMS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ019-026>028- 035>037-041-042-045-046-049>053-056>059-063>066. && $$ SYNOPSIS...GRUMM/STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...GRUMM/STEINBUGL LONG TERM...GRUMM/MARTIN AVIATION...CERU/STEINBUGL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1039 PM EDT SAT JUL 20 2013 .SYNOPSIS... HIGH PRESSURE OVER THE SOUTHEAST WILL WEAKEN DURING THE REMAINDER OF THE WEEKEND AS A COLD FRONT MOVES SOUTHWARD FROM THE GREAT LAKES. THE FRONT WILL STALL NORTH OF THE AREA ON SUNDAY AND THEN DISSIPATE OR RETURN NORTHWARD INTO MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EAST ON TUESDAY AND LINGER THROUGH LATE WEEK. A SECOND WEAK COLD FRONT WILL ARRIVE FROM THE NORTHWEST ON THURSDAY AND SETTLE JUST SOUTHEAST OF THE REGION THROUGH FRIDAY. && .NEAR TERM /THROUGH SUNDAY/... 1015 PM UPDATE...THUNDERSTORMS PERSIST AT THIS HOUR IN THE VICINITY OF A REMNANT GUST FRONT EXTENDING ACROSS THE LOWER SC PIEDMONT AND SOUTH SIDE OF THE CHARLOTTE METRO. LATEST SPC MESOANALYSIS SHOWS NEARLY 2000 J OF SBCAPE STILL UNINHIBITED JUST SOUTH OF THIS BOUNDARY...AS WELL AS A THERMAL GRADIENT IN THE SAME AREA THAT IS LIKELY PROVIDING ENOUGH FORCING TO GET PARCELS GOING. LIGHT SLY FLOW ON THE S SIDE OF THE BDY WILL CONTINUE TO REINFORCE THE GRADIENT AND IT MAY TAKE SOME TIME FOR THE REMNANT INSTABILITY TO BE CONSUMED. LATEST HRRR SUPPORTS THIS CONCEPT AS WELL AS THE SCHC POP WHICH HAS BEEN MAINTAINED OVERNIGHT FOR MOST OF THE CWFA...AS IT FEATURES A COUPLE OF ISOLATED CELLS HERE AND THERE...ESPECIALLY NEAR THE BLUE RIDGE. ON A FINAL NOTE...PATCHY FOG ALREADY DEVELOPING AT SOME SITES...PRIMARILY SITES WHICH SAW HEAVY RAIN THIS AFTN. FOLLOWING THAT THINKING THE MAIN AREA OF CONCERN WOULD BE THE FOOTHILLS AND UPPER PIEDMONT. AT THIS TIME THE REPORTING SITES ARE TOO SCATTERED TO NEED A DENSE FOG ADVY...AND NAM SOUNDINGS ARE NOT SUPPORTIVE OF WIDESPREAD DENSE FOG ANYWAY. HOWEVER...IT BEARS MONITORING AND WILL INFORM INCOMING SHIFT OF THIS CONCERN. AT 230 PM EDT SATURDAY...AN UPPER LEVEL TROUGH WILL SLOWLY AMPLIFY OVER THE EASTERN USA TONIGHT AND SUNDAY. A SHORTWAVE WILL MOVE INTO THE BASE OF THIS TROUGH OVER THE TN RIVER VALLEY LATE SUNDAY. DEEP GULF MOISTURE WILL BE TRANSPORTED NORTH INTO OUR AREA BY A GENTLE SW LOW LEVEL FLOW ON THE WEST SIDE OF A BERMUDA HIGH...WHILE A COLD FRONT DROPS SOUTH INTO VA. WITH LOW LEVEL FLOW NEARLY PARALLEL THE TO THE BLUE RIDGE...UPSLOPE FLOW WILL BE LIMITED...THOUGH STILL PRESENT. WITH THE LOWE LEVELS STABILIZING LATE THIS EVENING... CONVECTIVE COVER SHOULD DIMINISH. MODEL SOUNDINGS SHOW CAPE SURPASSING 1000 J/KG AGAIN ON SUNDAY...AND CONVECTIVE TRENDS ARE EXPECTED TO MIMIC TODAY...WITH THE GREATEST COVERAGE IN THE MOUNTAINS...WITH ACTIVITY SPREADING EAST INTO THE FOOTHILLS AND PIEDMONT WITH TIME. SHEAR WILL REMAIN WEAK HOWEVER...LIMITING STORM ORGANIZATION. MINIMUM TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL TONIGHT IN A MOIST AIR MASS. MAXIMUM TEMPERATURES SUNDAY WILL BE SLIGHTLY BELOW NORMAL...WITH CLOUDS...MOISTURE A FALLING HEIGHTS ALOFT LIMITING WARMING. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... AT 230 PM SATURDAY... 500 MB HEIGHTS GRADUALLY LOWER OVER THE SOUTHEAST MONDAY AND TUESDAY BUT SURFACE PATTERN CHANGES WILL BE RATHER SUBTLE. DIURNAL CONVECTION WILL CONTINUE INTO THE FORECAST PERIOD BEGINNING 00Z MONDAY THEN GRADUALLY DIMINISH DURING THE NIGHT. MOIST AND MODERATELY UNSTABLE AIR MASS WILL CONTINUE OVER THE REGION AND GFS DEPICTS SHORT WAVE TROUGH APPROACHING CWA BY 12Z MONDAY... SO AT LEAST SLIGHT CHANCE POPS WILL CONTINUE WELL INTO THE NIGHT. DURING DAYTIME MONDAY... CWA REMAINS IN AIRMASS CONDUCIVE TO CONVECTIVE STORM DEVELOPMENT SO POPS WILL INCREASE WITH DAYTIME HEATING INTO CHANCE CATEGORY WITH LIKELY POPS OVER HIGHER TERRAIN. GFS HAS ANOTHER SHORT WAVE TROUGH DROPPING INTO LONG WAVE TROUGH POSITION EARLY TUESDAY... SO CHANCE POPS WILL CONTINUE THROUGH THE NIGHT AND INTO TUESDAY WHEN DIURNAL HEATING CYCLE ONCE AGAIN LEADS TO HIGHER PROBABILITIES DURING AFTERNOON. NO SIGNIFICANT TEMPERATURE CHANGES WILL OCCUR DURING MONDAY TUESDAY. HIGHS OUTSIDE THE MOUNTAINS WILL BE IN THE UPPER 80S AND LOWER 90S WHILE MOUNTAIN VALLEY TEMPERATURES WILL BE IN THE LOWER TO MIDDLE 80S. VERY WARM LOW TEMPERATURES IN THE 60S AND LOWER 70S ARE EXPECTED TO CONTINUE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 230 PM SATURDAY... FLOW PATTERN ACROSS U.S. DURING THE PERIOD WILL CONSIST OF RIDGE IN THE WEST AND TROUGH OVER THE EASTERN STATES. BOUNDARY LAYER WILL REMAIN WARM AND MOIST SO COOL TEMPERATURES ALOFT ON WEDNESDAY WILL SUPPORT LAPSE RATES SUFFICIENTLY STEEP TO PROMOTE CONVECTION WITH APPROACH AND PASSAGE EARLY THURSDAY OF COLD FRONT. THEREAFTER DETAILS BECOME DIFFICULT TO RESOLVE AS FRONT DRIFTS SLOWLY SOUTHEAST AND APPEARS IN CURRENT GUIDANCE TO BECOME NEARLY STATIONARY JUST AFTER CROSSING CWA. THUS... AIR MASS CHANGE WILL NOT BE SUFFICIENTLY SIGNIFICANT TO ELIMINATE POPS BUT NUMBERS WILL BE IN THE LOWER END OF THE CHANCE SPECTRUM AND WILL DISPLAY A DIURNAL TREND. NO SIGNIFICANT CHANGES IN TEMPERATURE EXPECTED. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... AT KCLT...PATTERN LARGELY THE SAME AS LAST NIGHT SO PERSISTENCE WAS KEY TO FCST. LLVL MOISTURE ONCE AGAIN ABUNDANT AND GUIDANCE CONSENSUS IS LOW MVFR EARLY SUNDAY. WOULD NOT BE SURPRISED TO SEE IFR AROUND DAYBREAK THOUGH LACK OF RAINFALL IN THE IMMEDIATE VICINITY TODAY MAKES THAT A BIT LESS LIKELY. IMPROVEMENT LIKELY TO BE SOMEWHAT SLOW AFTER SUNRISE...WITH PERSISTENT LOW CIGS DELAYING THE ONSET OF DIURNAL INSTABILITY /CU AND TS DEVELOPMENT/. DEEPENING MOISTURE PUTS AFTN THUNDER CHANCES A BIT MORE THAN USUAL...BUT STILL ONLY WORTHY OF PROB30. WINDS WILL REMAIN LIGHT SOUTHERLY. ELSEWHERE...VFR DEBRIS FROM AFTN TSTMS WILL LINGER THIS EVENING...BUT WITH VERY MOIST CONDITIONS CONTINUING...LOW MVFR OR IFR CIGS WILL BEGIN TO DEVELOP OVER MUCH OF THE REGION BY MIDNIGHT. GUIDANCE GENERALLY IN AGREEMENT WHICH LENDS CONFIDENCE TO A RESTRICTIVE FCST MUCH LIKE THE CONDITIONS EARLY SATURDAY MRNG. CIGS WILL BE THE MAIN FACTOR WITH DENSE FOG LOOKING MOST LIKELY IN THE MTN VALLEYS /INCLUDING KAVL/. THE LOW CIGS WILL BE SLOW TO IMPROVE BUT SOUTHERLY WINDS WILL PROVIDE WEAK UPSLOPE FORCING TO ENHANCE PRECIP COVERAGE FROM MODEST DIURNAL INSTABILITY. PRECIP LIKELY ACRS THE MTNS AND FOOTHILLS BY LATE MRNG. OUTLOOK...MOIST SOUTHWESTERLY FLOW CONTINUES INTO THE EARLY WEEK. THIS WILL HELP DRIVE SHOWERS AND THUNDERSTORMS...MAINLY IN THE AFTERNOON AND EVENING...AND LIKELY CAUSE RESTRICTIVE CIGS/VSBYS EARLY EACH MORNING. CONFIDENCE TABLE... 02-08Z 08-14Z 14-20Z 20-02Z KCLT MED 78% MED 72% HIGH 86% HIGH 100% KGSP LOW 56% LOW 56% HIGH 86% HIGH 100% KAVL MED 75% MED 76% MED 61% MED 64% KHKY LOW 55% LOW 59% LOW 58% HIGH 100% KGMU LOW 52% LOW 55% LOW 59% HIGH 100% KAND MED 79% LOW 52% HIGH 86% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...JAT/WIMBERLEY SHORT TERM...LGL LONG TERM...LGL AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1037 PM EDT SAT JUL 20 2013 .SYNOPSIS... HIGH PRESSURE OVER THE SOUTHEAST WILL WEAKEN DURING THE REMAINDER OF THE WEEKEND AS A COLD FRONT MOVES SOUTHWARD FROM THE GREAT LAKES. THE FRONT WILL STALL NORTH OF THE AREA ON SUNDAY AND THEN DISSIPATE OR RETURN NORTHWARD INTO MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EAST ON TUESDAY AND LINGER THROUGH LATE WEEK. A SECOND WEAK COLD FRONT WILL ARRIVE FROM THE NORTHWEST ON THURSDAY AND SETTLE JUST SOUTHEAST OF THE REGION THROUGH FRIDAY. && .NEAR TERM /THROUGH SUNDAY/... 1015 PM UPDATE...THUNDERSTORMS PERSIST AT THIS HOUR IN THE VICINITY OF A REMNANT GUST FRONT EXTENDING ACROSS THE LOWER SC PIEDMONT AND SOUTH SIDE OF THE CHARLOTTE METRO. LATEST SPC MESOANALYSIS SHOWS NEARLY 2000 J OF SBCAPE STILL UNINHIBITED JUST SOUTH OF THIS BOUNDARY...AS WELL AS A THERMAL GRADIENT IN THE SAME AREA THAT IS LIKELY PROVIDING ENOUGH FORCING TO GET PARCELS GOING. LIGHT SLY FLOW ON THE S SIDE OF THE BDY WILL CONTINUE TO REINFORCE THE GRADIENT AND IT MAY TAKE SOME TIME FOR THE REMNANT INSTABILITY TO BE CONSUMED. LATEST HRRR SUPPORTS THIS CONCEPT AS WELL AS THE SCHC POP WHICH HAS BEEN MAINTAINED OVERNIGHT FOR MOST OF THE CWFA...AS IT FEATURES A COUPLE OF ISOLATED CELLS HERE AND THERE...ESPECIALLY NEAR THE BLUE RIDGE. AT 230 PM EDT SATURDAY...AN UPPER LEVEL TROUGH WILL SLOWLY AMPLIFY OVER THE EASTERN USA TONIGHT AND SUNDAY. A SHORTWAVE WILL MOVE INTO THE BASE OF THIS TROUGH OVER THE TN RIVER VALLEY LATE SUNDAY. DEEP GULF MOISTURE WILL BE TRANSPORTED NORTH INTO OUR AREA BY A GENTLE SW LOW LEVEL FLOW ON THE WEST SIDE OF A BERMUDA HIGH...WHILE A COLD FRONT DROPS SOUTH INTO VA. WITH LOW LEVEL FLOW NEARLY PARALLEL THE TO THE BLUE RIDGE...UPSLOPE FLOW WILL BE LIMITED...THOUGH STILL PRESENT. WITH THE LOWE LEVELS STABILIZING LATE THIS EVENING... CONVECTIVE COVER SHOULD DIMINISH. MODEL SOUNDINGS SHOW CAPE SURPASSING 1000 J/KG AGAIN ON SUNDAY...AND CONVECTIVE TRENDS ARE EXPECTED TO MIMIC TODAY...WITH THE GREATEST COVERAGE IN THE MOUNTAINS...WITH ACTIVITY SPREADING EAST INTO THE FOOTHILLS AND PIEDMONT WITH TIME. SHEAR WILL REMAIN WEAK HOWEVER...LIMITING STORM ORGANIZATION. MINIMUM TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL TONIGHT IN A MOIST AIR MASS. MAXIMUM TEMPERATURES SUNDAY WILL BE SLIGHTLY BELOW NORMAL...WITH CLOUDS...MOISTURE A FALLING HEIGHTS ALOFT LIMITING WARMING. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... AT 230 PM SATURDAY... 500 MB HEIGHTS GRADUALLY LOWER OVER THE SOUTHEAST MONDAY AND TUESDAY BUT SURFACE PATTERN CHANGES WILL BE RATHER SUBTLE. DIURNAL CONVECTION WILL CONTINUE INTO THE FORECAST PERIOD BEGINNING 00Z MONDAY THEN GRADUALLY DIMINISH DURING THE NIGHT. MOIST AND MODERATELY UNSTABLE AIR MASS WILL CONTINUE OVER THE REGION AND GFS DEPICTS SHORT WAVE TROUGH APPROACHING CWA BY 12Z MONDAY... SO AT LEAST SLIGHT CHANCE POPS WILL CONTINUE WELL INTO THE NIGHT. DURING DAYTIME MONDAY... CWA REMAINS IN AIRMASS CONDUCIVE TO CONVECTIVE STORM DEVELOPMENT SO POPS WILL INCREASE WITH DAYTIME HEATING INTO CHANCE CATEGORY WITH LIKELY POPS OVER HIGHER TERRAIN. GFS HAS ANOTHER SHORT WAVE TROUGH DROPPING INTO LONG WAVE TROUGH POSITION EARLY TUESDAY... SO CHANCE POPS WILL CONTINUE THROUGH THE NIGHT AND INTO TUESDAY WHEN DIURNAL HEATING CYCLE ONCE AGAIN LEADS TO HIGHER PROBABILITIES DURING AFTERNOON. NO SIGNIFICANT TEMPERATURE CHANGES WILL OCCUR DURING MONDAY TUESDAY. HIGHS OUTSIDE THE MOUNTAINS WILL BE IN THE UPPER 80S AND LOWER 90S WHILE MOUNTAIN VALLEY TEMPERATURES WILL BE IN THE LOWER TO MIDDLE 80S. VERY WARM LOW TEMPERATURES IN THE 60S AND LOWER 70S ARE EXPECTED TO CONTINUE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 230 PM SATURDAY... FLOW PATTERN ACROSS U.S. DURING THE PERIOD WILL CONSIST OF RIDGE IN THE WEST AND TROUGH OVER THE EASTERN STATES. BOUNDARY LAYER WILL REMAIN WARM AND MOIST SO COOL TEMPERATURES ALOFT ON WEDNESDAY WILL SUPPORT LAPSE RATES SUFFICIENTLY STEEP TO PROMOTE CONVECTION WITH APPROACH AND PASSAGE EARLY THURSDAY OF COLD FRONT. THEREAFTER DETAILS BECOME DIFFICULT TO RESOLVE AS FRONT DRIFTS SLOWLY SOUTHEAST AND APPEARS IN CURRENT GUIDANCE TO BECOME NEARLY STATIONARY JUST AFTER CROSSING CWA. THUS... AIR MASS CHANGE WILL NOT BE SUFFICIENTLY SIGNIFICANT TO ELIMINATE POPS BUT NUMBERS WILL BE IN THE LOWER END OF THE CHANCE SPECTRUM AND WILL DISPLAY A DIURNAL TREND. NO SIGNIFICANT CHANGES IN TEMPERATURE EXPECTED. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... AT KCLT...PATTERN LARGELY THE SAME AS LAST NIGHT SO PERSISTENCE WAS KEY TO FCST. LLVL MOISTURE ONCE AGAIN ABUNDANT AND GUIDANCE CONSENSUS IS LOW MVFR EARLY SUNDAY. WOULD NOT BE SURPRISED TO SEE IFR AROUND DAYBREAK THOUGH LACK OF RAINFALL IN THE IMMEDIATE VICINITY TODAY MAKES THAT A BIT LESS LIKELY. IMPROVEMENT LIKELY TO BE SOMEWHAT SLOW AFTER SUNRISE...WITH PERSISTENT LOW CIGS DELAYING THE ONSET OF DIURNAL INSTABILITY /CU AND TS DEVELOPMENT/. DEEPENING MOISTURE PUTS AFTN THUNDER CHANCES A BIT MORE THAN USUAL...BUT STILL ONLY WORTHY OF PROB30. WINDS WILL REMAIN LIGHT SOUTHERLY. ELSEWHERE...VFR DEBRIS FROM AFTN TSTMS WILL LINGER THIS EVENING...BUT WITH VERY MOIST CONDITIONS CONTINUING...LOW MVFR OR IFR CIGS WILL BEGIN TO DEVELOP OVER MUCH OF THE REGION BY MIDNIGHT. GUIDANCE GENERALLY IN AGREEMENT WHICH LENDS CONFIDENCE TO A RESTRICTIVE FCST MUCH LIKE THE CONDITIONS EARLY SATURDAY MRNG. CIGS WILL BE THE MAIN FACTOR WITH DENSE FOG LOOKING MOST LIKELY IN THE MTN VALLEYS /INCLUDING KAVL/. THE LOW CIGS WILL BE SLOW TO IMPROVE BUT SOUTHERLY WINDS WILL PROVIDE WEAK UPSLOPE FORCING TO ENHANCE PRECIP COVERAGE FROM MODEST DIURNAL INSTABILITY. PRECIP LIKELY ACRS THE MTNS AND FOOTHILLS BY LATE MRNG. OUTLOOK...MOIST SOUTHWESTERLY FLOW CONTINUES INTO THE EARLY WEEK. THIS WILL HELP DRIVE SHOWERS AND THUNDERSTORMS...MAINLY IN THE AFTERNOON AND EVENING...AND LIKELY CAUSE RESTRICTIVE CIGS/VSBYS EARLY EACH MORNING. CONFIDENCE TABLE... 02-08Z 08-14Z 14-20Z 20-02Z KCLT MED 78% MED 72% HIGH 86% HIGH 100% KGSP LOW 56% LOW 56% HIGH 86% HIGH 100% KAVL MED 75% MED 76% MED 61% MED 64% KHKY LOW 55% LOW 59% LOW 58% HIGH 100% KGMU LOW 52% LOW 55% LOW 59% HIGH 100% KAND MED 79% LOW 52% HIGH 86% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...JAT/WIMBERLEY SHORT TERM...LGL LONG TERM...LGL AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
441 PM EDT FRI JUL 19 2013 .SYNOPSIS... HIGH PRESSURE WILL WEAKEN AND TRACK EAST THROUGH SATURDAY. A COLD FRONT WILL APPROACH THE AREA FROM THE NORTHWEST ON SUNDAY...STALLING AND DISSIPATING IN THE VICINITY THROUGH EARLY NEXT WEEK. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EAST TUESDAY AND MOVE THROUGH THE AREA ON WEDNESDAY...WITH A SECOND WEAK COLD FRONT ARRIVING FROM THE NORTHWEST FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... 415 PM UPDATE...WILL MAINTAIN POPS LARGELY AS-IS. SPC MESOANALYSIS SHOWS SBCAPE IN 2500-3500 J RANGE ACRS THE AREA. BEST COVERAGE ATTM IS IN THE MTNS AND CONGESTED CU ARE ALIGNED ALONG RIDGETOPS SO THIS COVERAGE IS STILL CAPABLE OF INCREASING FURTHER. REVISED PIEDMONT POPS SUCH THAT BEST CHANCES ARE ALIGNED WITH THE BAND OF BETTER CU FROM AROUND ELBERTON TO SALISBURY. THERE DOES APPEAR TO BE AN AREA OF LOCAL SCALE SUBSIDENCE IN THE MIDLANDS SUPPRESSING CU GROWTH. THIS IS WORKING NORTHWESTWARD...BUT THE CU IN THAT BAND ARE STILL GROWING SO SOME CHANCE REMAINS IN THE PIEDMONT. 17Z HRRR DEVELOPS CELLS AROUND SUNSET IN THE MTNS WHICH MARCH ACROSS THE NRN THIRD OF THE CWFA THRU 03Z APPARENTLY ALONG AN OUTFLOW BOUNDARY. THIS IS RATHER UNUSUAL BUT LAST NIGHT CELLS DID FIRE ALONG OUTFLOW IN THE VERY MOIST AIR AT THAT TIME OF DAY. WILL MONITOR TRENDS IN SHORT TERM GUIDANCE. AT 220 PM EDT FRIDAY...AN UPPER TROUGH WILL SLOWLY AMPLIFY OVER THE GREAT LAKES TONIGHT AND SATURDAY...WHILE AN ATLANTIC UPPER RIDGE PROGRESSES FARTHER OUT TO SEA. MEANWHILE...A COLD FRONT WILL MOVE SOUTHEAST...FROM THE UPPER MS RIVER VALLEY TO THE OH RIVER VALLEY. LIGHT SSW LOW LEVEL FLOW WILL MAINTAIN RICH MOISTURE OVER OUR AREA BELOW 700 MB. THE MODELS DISAGREE ON WEATHER THIS AFTERNOON OR SATURDAY AFTERNOON WILL HAVE BETTER INSTABILITY...BUT ENOUGH SHOULD BE PRESENT FOR SCATTERED CONVECTION EACH DAY...WITH THE BETTER COVERAGE IN THE MOUNTAINS DUE TO OROGRAPHIC EFFECTS. WITH WEAK SHEAR...STORM ORGANIZATION SHOULD BE LIMITED. STEERING FLOW IS GENERALLY SHOWN TO BE LIGHT IN MODEL SOUNDINGS...SUGGESTING THAT SLOW TRACKING STORMS COULD PRODUCE HEAVY PRECIPITATION...AND PERHAPS ISOLATED FLASH FLOODING. MINIMUM TEMPERATURES TONIGHT WILL BE ABOVE NORMAL TONIGHT IN A MOIST ATMOSPHERE. MAXIMUM TEMPERATURES SATURDAY WILL BE SLIGHTLY COOLER THAN TODAY AND NEAR NORMAL AS HEIGHTS FALL ALOFT. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 215 PM EDT FRIDAY...AN UNSETTLED PERIOD IS SETTING UP FOR THE SHORT TERM AS AN UPPER TROUGH AMPLIFIES OVER THE GREAT LAKES THROUGH THE WEEKEND. A COLD FRONT WILL MOVE SLOWLY SOUTHEAST FROM THE OHIO VALLEY AND SETTLE OVER NORTH CAROLINA ON SUNDAY AFTERNOON AND THEN MOVE NORTH AGAIN ON MONDAY. AS THE UPPER TROUGH AMPLIFIES TO THE NORTH...A LIGHT ZONAL FLOW ALOFT WILL DEVELOP ON SUNDAY AND THEN BECOME SW ON MONDAY AS A SHORT WAVE APPROACHES. LOOKS LIKE CONVECTION WILL STILL HAVE MAINLY A DIURNAL MODE...ESPECIALLY SAT NIGHT WHEN NO APPARENT FORCING WILL BE IN PLACE TO MAINTAIN UPDRAFTS AFTER THE LOSS OF HEATING. HENCE...RAMPED POPS DOWN QUICKLY SAT EVENING. ON SUN...SHOWERS/STORMS ARE EXPECTED TO BECOME NUMEROUS AGAIN BY AFTERNOON OVER THE MOUNTAINS AS THE WEAK FRONT DROPS INTO THE NORTHERN PORTION OF AREA. SHOULD SEE AT LEAST SCT SHOWERS/THUNDERSTORMS ELSEWHERE AS SBCAPES APPROACH 1500J DURING THE AFTERNOON. CONVECTION LOOKS LIKE IT WILL BE SLOWER TO ABATE SUN NIGHT AS UPPER DIVERGENCE IMPROVES...BUT HAVE BACKED POPS DOWN TO <15% OUTSIDE OF THE MOUNTAINS AFTER MIDNIGHT. ON MONDAY...EXPECT ANOTHER DAY WHERE SHOWERS/THUDNERSTORMS WILL BECOME NUMEROUS DURING THE AFTERNOON HOURS AS A SHORT WAVE APPROACHES FROM THE WEST AND UPPER DIVERGENCE CONTINUES. USED A CONSENSUS APPROACH TO GRID FIELDS. MAX TEMPS ARE FORECAST TO BE ABOUT A CATEGORY SHY OF AVERAGE DUE TO INCREASED CLOUD COVER AND PRECIP COVERAGE. LOWS WILL BE A LITTLE ABOVE AVERAGE. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AT 200 PM EDT FRIDAY...BOTH THE ECMWF AND GFS INDICATE THAT A H5 TROF WILL START TO AMPLIFY ACROSS THROUGH SOUTHERN APPALACHIAN REGION ON TUESDAY. A SHORT WAVE EMBEDDED IN THE TROF AXIS IS EXPECTED TO RIPPLE ACROSS THE FORECAST AREA DURING THE HEAT OF TUES AFTERNOON. FORECAST SOUNDINGS INDICATE THAT MILD MID LEVEL TEMPERATURES WILL REMAIN OVER THE REGION...RESULTING CAPE VALUES OF 500-1000 J/KG. THE PASSAGE OF THE S/W COMBINED WITH THE POOL OF MARGINAL CAPES TO SUPPORT INCREASING COVERAGE THROUGH THE AFTERNOON. I WILL FORECAST LIKELY POPS ACROSS THE MTNS WITH HIGH CHC EAST. HIGH TEMPERATURES UNDER DECREASING THICKNESSES AND PARTLY TO MOSTLY CLOUDY SKY COVER SHOULD REMAIN A COUPLE OF DEGREES BELOW NORMAL. WEDNESDAY AND THURSDAY...THE LONG WAVE TROUGH WILL REMAIN OVER THE REGION. GFS FORECAST SOUNDINGS INDICATE THAT MID LEVEL TEMPERATURES WILL SLOWLY COOL...RESULTING IN AN INCREASE IN CAPES FROM DAY TO DAY. WEAK DISTURBANCES WILL LIKELY CONTINUE TO TRACK ACROSS THE REGION...SUPPORTING SCT TO NUM SHRA/TSRA DURING THE EAST OF THE AFTERNOON. THE GREATEST COVERAGE SHOULD OCCUR OVER THE MTNS. TEMPERATURES SHOULD CONTINUE TO RANGE 2-3 DEGREES BELOW NORMAL. FRIDAY...MEDIUM RANGE GUIDANCE INDICATES THAT THE L/W TROUGH AXIS WILL PIVOT EAST OF THE CWA. DRIER AIR MAY ARRIVE FROM THE WEST...IN THE WEAK OF A WEAK COLD FRONT. HOWEVER...MOISTURE WILL LIKELY LINGER ACROSS THE FOOTHILLS AND PIEDMONT. GFS FORECAST SOUNDINGS CONTINUE TO INDICATE MARGINAL DIURNAL CAPE ACROSS THE REGION. IT APPEARS THAT AT LEAST SCT SHRA/TSRA WILL DEVELOP ALONG AND AHEAD OF THE SFC BOUNDARY. I WILL FORECAST 30 TO 40 POPS ACROSS THE REGION. TEMPERATURES WILL REMAIN COMPARABLE TO THE TUES THROUGH WED PERIOD. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...GUIDANCE IS NOT VERY SUPPORTIVE OF RESTRICTIONS...CARRYING ONLY LOW VFR VSBY AT DAYBREAK SATURDAY. ROBUST INSTABILITY WILL SUPPORT ENOUGH LATE AFTERNOON AND EARLY EVENING CONVECTION TO CARRY A MENTION IN THE TAF...WITH MVFR CIG AND VSBY RESTRICTIONS POSSIBLE. LIGHT SSW WINDS WILL PERSIST. ELSEWHERE...A BLEND OF ADJMAV AND ADJMET GUIDANCE FAVORS MVFR VSBY IN DAYBREAK FOG AT KAVL...WITH LOW VFR VSBY AT FOOTHILLS SITES. THE BEST BET FOR CIGS WILL BE IN THE MOUNTAINS...WHERE MODEL TIME HEIGHTS SUGGEST A BORDERLINE MVFR CIG AT KAVL THIS AFTERNOON/ OF COURSE...ANY SITE THAT HAS A THUNDERSTORM MOVE OVERHEAD THIS AFTERNOON OR EVENING WILL HAVE A CHANCE OF MVFR CIG AND VSBY RESTRICTIONS DURING THE STORM...AND AGAIN AT DAYBREAK IN A RAIN MOISTENED ATMOSPHERE. LIGHT WINDS WILL FAVOR THE SSW...EXCEPT IN THE MOUNTAINS TONIGHT WHERE THEY WILL VEER TO THE NW TONIGHT. OUTLOOK...A COLD FRONT WILL SAG SEWD INTO THE AREA THIS WEEKEND. EXPECT ABOVE NORMAL TSRA COVERAGE SUNDAY AND INTO EARLY NEXT WEEK...WITH BEST CHANCES STILL DURING AFTERNOONS AND EVENINGS. CONFIDENCE TABLE... 20-02Z 02-08Z 08-14Z 14-20Z KCLT HIGH 100% HIGH 100% HIGH 98% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 96% HIGH 100% KAVL LOW 56% LOW 53% MED 67% MED 61% KHKY HIGH 100% HIGH 100% HIGH 86% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 96% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 94% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...GOODMAN NEAR TERM...JAT/WIMBERLEY SHORT TERM...LG LONG TERM...GOODMAN/NED AVIATION...JAT
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
931 PM CDT SAT JUL 20 2013 .UPDATE... UPDATED TO INCREASE POPS IN CENTRAL SOUTH DAKOTA WITH QUITE A FEW STORMS SHOWN ON RADAR. ALSO...SOME NEW DEVELOPMENT SHOWING UP IN NORTH CENTRAL SOUTH DAKOTA. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT SEVERAL WEAK SHORT WAVES EMBEDDED WITHIN THE NORTHWEST FLOW ALOFT WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS ACROSS THE REGION THIS EVENING THOUGH SUNDAY. WITH HI-RES MODELS STRUGGLING TO DEPICT THE AREAS OF CONVECTION...WITH MAINTAIN AT LEAST A LOW POP THROUGH 18Z SUNDAY. AS OF 19Z...A NARROW LINE OF SHOWERS ARE MOVING SE ACROSS HYDE/HAND COUNTY. THESE STORMS SHOULD CONTINUE TO DISSIPATE AS THEY EXIT THIS CWA. FARTHER WEST...A MORE PRONOUNCED SHORT WAVE HAS CAUSED CONVECTION A DEVELOP OVER THE BLACK HILLS. THIS AREA IS BASICALLY UNCAPPED WITH SB-CAPE VALUES AROUND 2000 J/KG. THESE STORMS SHOULD CONTINUE TO GROW AS SOUTH TO EASTERLY LOW LEVEL FLOW WILL FILTER MOISTURE INTO SW SOUTH DAKOTA. WOULD EXPECT THESE STORM WILL REMAIN JUST SOUTH OF THE CWA AS THE LAYER STORM MOTION OFF THE RUC SUGGEST A SE MOTION. THAT SAID...SEVERAL OUTFLOW BOUNDARIES FROM EARLIER CONVECTION COULD RESULT IN A NORTHWARD JOG. CHANCES FOR THUNDERSTORMS IN THE EASTERN CWA TONIGHT/SUNDAY IS A LITTLE UNCLEAR AT THIS TIME. HALF THE MODEL SUGGEST LLJ INDUCED THUNDERSTORMS MOVING ACROSS THE EASTERN DAKOTAS BY 12Z. OTHERS SUGGEST CONVECTION COULD BE SOUTH/EAST/OR NORTH OF THIS CWA. WITH VERY LOW CONFIDENCE...WILL BROAD BRUSH MOST OF THE CWA WITH LOW POPS FOR NOW ON SUNDAY. AN AREA OF LOW PRESSURE AND SURFACE COLD FRONT WILL MOVE ACROSS THE REGION ON SUNDAY NIGHT/MONDAY MORNING. WITH THE MAJORITY OF THE PCPN FALLING POST FRONTAL...SEVERE STORMS DO NOT APPEAR POSSIBLE. COOLER TEMPERATURES ARE EXPECTED ON MONDAY WITH HIGHS IN THE UPPER 70S..IN THE NE...TO AROUND 90 IN THE SOUTHWEST CWA. A BLEND OF CONSALL/ALLBLEND SHOWS HIGHS COULD BE SLIGHTLY COOLER THAN CURRENTLY ADVERTISED. .LONG TERM...TUESDAY THROUGH SATURDAY NORTHWEST FLOW ALOFT WILL DOMINATE THROUGH THE EXTENDED. MAIN FORECAST CHALLENGE WILL BE TIMING SHORTWAVE ACTIVITY. THE PATTERN WILL REMAIN VERY ACTIVE THROUGH THURSDAY WITH A SERIES OF SHORTWAVES. TIMING AND INTENSITY ARE VERY DIFFICULT TO DETERMINE AT THIS TIME RANGE SO CONFIDENCE IN POPS IN ANY GIVEN PERIOD IS LOW. THAT SAID TUESDAY NIGHT DOES SEEM TO HAVE MODEL AGREEMENT ON BEING DRY WHILE THURSDAY HAS BEEN CONSISTENTLY STORMY. STUCK CLOSE TO ALLBLEND POPS BECAUSE OF UNCERTAINTY. BY FRIDAY SFC HIGH PRESSURE BEGINS TO DROP OUT OF CANADA AND NOSE INTO EASTERN SD. THE START OF THE WEEKEND APPEARS DRY FOR NOW AS A RESULT. TEMPERATURES WILL BE MUCH COOLER THROUGH THE PERIOD WITH HIGHS RANGING FROM THE UPPER 70S IN THE EAST TO THE MID 80S IN THE SOUTHWEST. && .AVIATION... 00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED AT ALL TAF LOCATIONS THROUGH TONIGHT AND SUNDAY. A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE REGION TONIGHT AND SUNDAY AND MAY AFFECT THE TERMINALS AT OR IN THE VICINITY. WILL WATCH FOR POSSIBLE AMENDMENTS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...SD LONG TERM...WISE AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
705 PM CDT SAT JUL 20 2013 .UPDATE... 00Z AVIATION DISCUSSION UPDATED BELOW. && .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT SEVERAL WEAK SHORT WAVES EMBEDDED WITHIN THE NORTHWEST FLOW ALOFT WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS ACROSS THE REGION THIS EVENING THOUGH SUNDAY. WITH HI-RES MODELS STRUGGLING TO DEPICT THE AREAS OF CONVECTION...WITH MAINTAIN AT LEAST A LOW POP THROUGH 18Z SUNDAY. AS OF 19Z...A NARROW LINE OF SHOWERS ARE MOVING SE ACROSS HYDE/HAND COUNTY. THESE STORMS SHOULD CONTINUE TO DISSIPATE AS THEY EXIT THIS CWA. FARTHER WEST...A MORE PRONOUNCED SHORT WAVE HAS CAUSED CONVECTION A DEVELOP OVER THE BLACK HILLS. THIS AREA IS BASICALLY UNCAPPED WITH SB-CAPE VALUES AROUND 2000 J/KG. THESE STORMS SHOULD CONTINUE TO GROW AS SOUTH TO EASTERLY LOW LEVEL FLOW WILL FILTER MOISTURE INTO SW SOUTH DAKOTA. WOULD EXPECT THESE STORM WILL REMAIN JUST SOUTH OF THE CWA AS THE LAYER STORM MOTION OFF THE RUC SUGGEST A SE MOTION. THAT SAID...SEVERAL OUTFLOW BOUNDARIES FROM EARLIER CONVECTION COULD RESULT IN A NORTHWARD JOG. CHANCES FOR THUNDERSTORMS IN THE EASTERN CWA TONIGHT/SUNDAY IS A LITTLE UNCLEAR AT THIS TIME. HALF THE MODEL SUGGEST LLJ INDUCED THUNDERSTORMS MOVING ACROSS THE EASTERN DAKOTAS BY 12Z. OTHERS SUGGEST CONVECTION COULD BE SOUTH/EAST/OR NORTH OF THIS CWA. WITH VERY LOW CONFIDENCE...WILL BROAD BRUSH MOST OF THE CWA WITH LOW POPS FOR NOW ON SUNDAY. AN AREA OF LOW PRESSURE AND SURFACE COLD FRONT WILL MOVE ACROSS THE REGION ON SUNDAY NIGHT/MONDAY MORNING. WITH THE MAJORITY OF THE PCPN FALLING POST FRONTAL...SEVERE STORMS DO NOT APPEAR POSSIBLE. COOLER TEMPERATURES ARE EXPECTED ON MONDAY WITH HIGHS IN THE UPPER 70S..IN THE NE...TO AROUND 90 IN THE SOUTHWEST CWA. A BLEND OF CONSALL/ALLBLEND SHOWS HIGHS COULD BE SLIGHTLY COOLER THAN CURRENTLY ADVERTISED. .LONG TERM...TUESDAY THROUGH SATURDAY NORTHWEST FLOW ALOFT WILL DOMINATE THROUGH THE EXTENDED. MAIN FORECAST CHALLENGE WILL BE TIMING SHORTWAVE ACTIVITY. THE PATTERN WILL REMAIN VERY ACTIVE THROUGH THURSDAY WITH A SERIES OF SHORTWAVES. TIMING AND INTENSITY ARE VERY DIFFICULT TO DETERMINE AT THIS TIME RANGE SO CONFIDENCE IN POPS IN ANY GIVEN PERIOD IS LOW. THAT SAID TUESDAY NIGHT DOES SEEM TO HAVE MODEL AGREEMENT ON BEING DRY WHILE THURSDAY HAS BEEN CONSISTENTLY STORMY. STUCK CLOSE TO ALLBLEND POPS BECAUSE OF UNCERTAINTY. BY FRIDAY SFC HIGH PRESSURE BEGINS TO DROP OUT OF CANADA AND NOSE INTO EASTERN SD. THE START OF THE WEEKEND APPEARS DRY FOR NOW AS A RESULT. TEMPERATURES WILL BE MUCH COOLER THROUGH THE PERIOD WITH HIGHS RANGING FROM THE UPPER 70S IN THE EAST TO THE MID 80S IN THE SOUTHWEST. && .AVIATION... 00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED AT ALL TAF LOCATIONS THROUGH TONIGHT AND SUNDAY. A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE REGION TONIGHT AND SUNDAY AND MAY AFFECT THE TERMINALS AT OR IN THE VICINITY. WILL WATCH FOR POSSIBLE AMENDMENTS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...SD LONG TERM...WISE AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1049 PM MDT THU JUL 18 2013 .UPDATE... ISSUED AT 821 PM MDT THU JUL 18 2013 02Z SURFACE ANALYSIS SHOWED COOL FRONT/TROUGH EXITING CWA. DIURNAL CYCLE TAKING IT/S TOLL ON TSRA WITH ACTIVITY ABOUT DONE SAVE FOR SOME ANVIL DEBRIS. LOOKS PRETTY QUITE OVERNIGHT PER 00Z RAP AND 00Z KUNR SOUNDING. WILL LEAVE SMALL POPS NEAR THE NE BORDER GIVEN NUMEROUS BOUNDARIES AND PROXIMITY TO 850-700MB FRONT AND ELEVATED INSTABILITY. && .SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT ISSUED AT 221 PM MDT THU JUL 18 2013 NORTHERN STREAM IMPULSE CONTINUES TO ADVECT/PROPAGATE TO THE EAST ACROSS SOUTHERN SK/MB WITH AN ORPHANING TROUGH AXIS OVER THE SOUTHERN FA. MOISTURE POOLING JUST BEHIND THE TROUGH COUPLED WITH DIURNAL HEATING/SOUTHERN BH CONVERGENCE/AND WEAK LSA HAS SUPPORTED A CLUSTER OF THUNDERSTORMS OVER THE SOUTHERN BH...WITH ADDITIONAL CELLS EXPECTED TO INITIATE ACROSS THE EASTERN AND SOUTHERN FA THIS AFTERNOON AND EVENING...AS THE TROUGH PROGRESSES SE AND INHIBITION WEAKENS PER DIURNAL HEATING. CELLS WILL CONTINUE TO FIGHT THE CAPPING INVERSION ACROSS THE EASTERN AND SE FA WITH FAIRLY WARM TEMPS ALOFT HIGHLY LIMITING CAPE. MARGINAL TO WEAK DEEP LAYER SHEAR SHOULD PREVENT MOST STORMS FROM ORGANIZATION...REMAINING PULSE DRIVEN. WIDESPREAD MASSIVE CONUS RIDGE WILL EVENTUALLY FLATTEN AS A STRONGER MORE PRONOUNCED UPPER SHORTWAVE DIGS SE INTO THE GREAT LAKES THROUGH FRIDAY. MEANWHILE...LOCAL DEEP LAYER FLOW WILL TURN NW...WITH IMPULSES ORIGINATING FROM THE CLOSED NE PAC UPPER LOW EXPECTED IN THE FLOW. AFOREMENTIONED TROUGH AND ASSOCIATED LL MOISTURE BUBBLE WITH THETA-E POOLING WILL RESIDE OVERT THE SW FA THROUGH FRIDAY NIGHT. FORECAST MODELS ARE IN RATHER STRONG AGREEMENT THAT A WEAK...BUT SUFFICIENT IMPULSE WILL PASS THROUGH THE FLOW FRI NIGHT...WITH REFLECTED FRONT SIDE SOUTHERLY FLOW /INDICATED WELL AT H7/ EXPECTED TO SUPPORT A PERIOD OF POS THETA-E ADV UNDER FAIRLY STEEP MID LEVEL LAPSE RATES. GIVEN AMPLE LL SLIGHTLY ELEVATED MOISTURE IN PLACE...SHOWER AND THUNDERSTORMS CHANCES LOOK GOOD OVER THE REGION...WITH THE POSSIBLY OF A SMALL MCS. THERE IS A SMALL POTENTIAL FOR A SEVERE STORM OR TWO FRI NIGHT. PROGGED DEEP LAYER SHEAR UTILIZING AN ELEVATED PARCEL SUGGEST 30 TO 45 KNOTS OF BULK SHEAR...WITH MU CAPE AOA 1000 J/KG ACROSS THE FAR SW FA PER NAM DATA. THIS WILL HAVE TO WATCHED. RETAINED LOW CHANCE POPS ACROSS THE SE FA THROUGH THIS EVENING...WITH LOW SLIGHTS ACROSS THE FAR SW LATE TONIGHT FOR POSSIBLE ELEVATED SHOWERS...WHICH MAY END UP AS JUST VIRGA. ALSO RETAINED LOW SLIGHTS ACROSS THE SW FA FRI GIVEN THE COLLOCATION OF THE LL THETA-E PLUME. HOWEVER...MODEL DATA SUGGEST THAT THIS PLUME OF MOISTURE WILL REMAIN ELEVATED. HENCE...ANY MODEL GENERATED QPF IN THIS PERIOD MAY BE FROM AN ACCAS PLUME. DID TREND POPS UP ACROSS THE SW HALF FRIDAY NIGHT GIVEN ABOVE CONCERNS. AS FOR TEMPS...WARM TO HOT CONDITIONS CAN BE EXPECTED MOST PLACES FRIDAY...ALTHOUGH 5 TO 10 DEGREES COOLER THAN TODAY/S TEMPS AS THE THERMAL RIDGE SHIFTS EAST. LOWS GENERALLY IN THE 60S CAN BE EXPECTED BOTH TONIGHT AND FRIDAY NIGHT. && .LONG TERM...SATURDAY THROUGH THURSDAY ISSUED AT 221 PM MDT THU JUL 18 2013 BROAD...RELATIVELY FLAT LONG WAVE RIDGE HAS RETROGRESSED TO ABOUT 105W WITH NEXT UPSTREAM TROF NEAR 130W. RIDGE IS FCST BY BOTH GFS AND ECMWF MODELS TO CONTINUE MOVING W WARD TO NEAR THE PAC COAST BY 12Z SATURDAY AND TO NEAR 130W BY 12Z SUNDAY. THE TREND IS THEN FOR IT TO MOVE SLOWLY E WARD AND AMPLIFY A BIT BY 12Z WED. THIS PLACES WEAK WNW FLOW OVER OUR CWA DURING ALL OF THE LONG TERM PERIOD. SEVERAL WEAK SHORT WAVES WILL MOVE ACROSS THE AREA IN THIS FLOW. TIMING OF THESE WAVES IS HANDLED VERY DIFFERENTLY BY EACH OF THE MODELS...SO HAVE NOT TRIED TO PIN THEM DOWN TOO CLOSELY IN POPS. STAYED CLOSE TO GUIDANCE IN TEMPS WITH LITTLE REASON TO DEPART. AS NOTED BY PREVIOUS SHIFT...EXTENDED GRID INITIALIZATION PLACED DEW POINTS THE LOOK TOO HIGH OVER OUR WY COUNTIES. THE INITIALIZATION IS NOT HANDLING DIURNAL DEW POINT TRENDS WELL...SO MOST NIGHT TIME DEW POINTS WERE LOWERED CLOSER TO GFS AND EURO MOS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1045 PM MDT THU JUL 18 2013 ISOLATED TSRA ARE POSSIBLE FOR THE REST OF TONIGHT NEAR THE NE BORDER. AFTER A QUIET MORNING...ADDITIONAL TSRA WILL DEVELOP OVER WY FRIDAY AFTERNOON...SPREADING EAST/NORTH ACROSS SD LATER FRIDAY AFTERNOON/NIGHT. VFR CONDITIONS WILL PREVAIL OUTSIDE OF TSRA...EXCEPT FOR LOCAL MVFR CIGS/VSBYS IN/NEAR STORMS. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...BARBER AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
953 PM CDT SAT JUL 20 2013 .UPDATE... DIURNALLY DRIVEN SHOWERS HAVE DISSIPATED ACROSS WEST CENTRAL TX BUT WE CONTINUE TO SEE ECHOES ROTATING TO THE NORTHWEST AROUND THE MID/UPPER LEVEL CYCLONE NEAR THE BIG BEND. POPS WERE REMOVED ACROSS MOST OF THE FORECAST AREA THROUGH THE REMAINDER OF THE OVERNIGHT PERIOD BUT I DID RETAIN A SLIGHT CHANCE OF SHOWERS IN THE SOUTH...MAINLY CROCKETT AND SUTTON COUNTIES DUE TO THE PROXIMITY OF THIS UPPER LOW. BOTH THE 3K TTU WRF AND HRRR DEPICT WEAK CONVECTION MOVING INTO THIS AREA AFTER MIDNIGHT. OTHERWISE...ONLY MINOR MODIFICATIONS WERE MADE TO THE INHERITED FORECAST. JOHNSON && .PREV DISCUSSION... /ISSUED 633 PM CDT SAT JUL 20 2013/ DISCUSSION... SEE AVIATION DISCUSSION BELOW/ AVIATION... CURRENTLY ISOLATED SHOWERS HAVE DEVELOPED ACROSS MASON...MCCULLOUGH...MENARD...COLEMAN...SHACKELFORD AND SUTTON COUNTIES. AN ISOLATED SHOWER WAS NOTED JUST NORTH OF SAN ANGELO. MOST OF THESE SHOWERS ARE EXPECTED TO DISSIPATE AFTER SUNSET. ON SUNDAY THERE IS POTENTIAL FOR ISOLATED SHOWERS TO REDEVELOP... CAUSED BY AFTERNOON HEATING THAT WILL CAUSE WARM AIR TO RISE THROUGH A WEAKLY CAPPED ATMOSPHERE THAT HAS MOIST AIR IN THE LOWEST 5K FEET. THE MOST LIKELY SHOWER AREAS WILL BE ACROSS MASON...KIMBLE... SUTTON...MENARD AND SAN SABA COUNTIES. HOWEVER...MOSTLY VFR CONDITIONS WILL PREVAIL THE NEXT 24 HOURS ACROSS THE FORECAST AREA. PREV DISCUSSION... /ISSUED 349 PM CDT SAT JUL 20 2013/ SHORT TERM... /TONIGHT AND SUNDAY/ .ISOLATED BRIEF SHOWERS AND THUNDERSTORMS INTO SUNDAY... MOIST LOW LEVEL MOISTURE WILL CONTINUE WITH A WEAKLY OR UNCAPPED ATMOSPHERE INTO SUNDAY. MOST STORMS EXPECTED TO DEVELOP MID AND LATE AFTERNOON UNDER MAXIMUM HEATING...THEN DISSIPATE AFTER SUNSET. HOWEVER...A FEW STORMS MAY LAST LONGER OVER SOUTHERN SECTIONS ALONG THE I-10 CORRIDOR AT NIGHT WHERE THE THE UPPER RIDGE IS WEAKEST. BRIEF HEAVY RAIN IS POSSIBLE IN SLOW MOVING STORMS. LONG TERM... THERE IS A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN SECTIONS ON MONDAY WITH DRY AND WARMER WEATHER FOR THE REMAINDER OF NEXT WEEK. A WEAK UPPER LEVEL LOW WILL BE SITUATED NEAR THE BIG BEND SUNDAY EVENING AND WILL DRIFT SOUTHWEST INTO NORTHERN MEXICO BY TUESDAY AFTERNOON. WE WILL STILL SEE A DECENT AMOUNT OF LOW AND MID LEVEL MOISTURE AROUND...ESPECIALLY ACROSS SOUTHERN SECTIONS ON MONDAY. KEPT INHERITED LOW POPS INTACT MAINLY OVER THE NORTHWEST HILL COUNTRY AND NORTHERN EDWARDS PLATEAU MONDAY AND MONDAY EVENING WHERE WIDELY SCATTERED SHOWERS AND FEW THUNDERSTORMS WILL BE POSSIBLE. HIGHS ON MONDAY WILL BE MAINLY IN THE LOW TO MID 90S WITH A FEW READINGS IN THE UPPER 90S ACROSS THE NORTHERN BIG COUNTRY. AN UPPER LEVEL RIDGE WILL BUILD SOUTHEAST ACROSS THE SOUTHERN ROCKIES AND INTO CENTRAL TEXAS TUESDAY THROUGH THE END OF THE WEEK. THE ECMWF DOES SHUNT THE RIDGE BACK TO THE WEST FRIDAY INTO SATURDAY AS A SHORT WAVE DROPS SOUTHEAST FROM THE NORTHERN ROCKIES...WITH AN ASSOCIATED WEAK COLD FRONT ENTERING THE AREA. THE GFS MAINTAINS A STRONGER RIDGE WITH THE FRONT REMAINING NORTH OF THE AREA. KEPT A DRY FORECAST GOING FOR NOW GIVEN THESE MODEL DISCREPANCIES. HIGH TEMPERATURES WILL WARM FROM THE LOW TO MID 90S ON TUESDAY...TO THE MID AND UPPER 90S WEDNESDAY THROUGH SATURDAY. OVERNIGHT LOWS WILL MAINLY BE IN THE LOWER 70S THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 71 93 72 94 74 / 5 10 10 10 10 SAN ANGELO 70 93 72 94 74 / 10 20 10 20 10 JUNCTION 70 92 72 93 73 / 10 30 20 20 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 25
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1231 PM CDT FRI JUL 19 2013 .DISCUSSION... SEE AVIATION FOR THE 18Z TAF DISCUSSION. && .AVIATION... AT 17Z AN AREA OF SHOWERS AND THUNDERSTORMS WAS LOCATED OVER NORTHEAST TEXAS MOVING SOUTHWEST AT 15 MPH. THE LATEST RUC13 AND EXTRAPOLATION OF CURRENT MOVEMENT SUGGESTS CONVECTION WILL IMPACT KAUS AS EARLY AS 23Z. THUS WILL GO WITH A 3 HOUR TEMPO GROUP AT KAUS. ISOLATED CONVECTION IS ALSO EXPECTED ALONG THE INLAND MOVING SEA-BREEZE BOUNDARY THIS AFTERNOON. THE ISOLATED NATURE OF THIS ACTIVITY DOES NOT WARRANT INCLUSION IN THE KSAT OR KSSF TAFS ATTM. OTHERWISE VFR CONDITIONS WILL PREVAIL THIS AFTERNOON AND EVENING...WITH MVFR IN AND NEAR TSTMS. MVFR CIGS WILL FORM AT THE I-35 TERMINALS BETWEEN 09Z AND 10Z...REACHING KDRT BY 11Z. CIGS WILL IMPROVE TO VFR BY 17Z WITH ISOLATED AFTERNOON CONVECTION EAST OF A KBMQ...KSAT...KFTN LINE. SFC WINDS WILL BE SOUTHERLY AT 5 TO 10 KTS WITH CONVECTIVE OUTFLOW GUSTS OF 20 TO 30 KTS POSSIBLE THIS AFTERNOON AND EVENING. && .PREV DISCUSSION... /ISSUED 630 AM CDT FRI JUL 19 2013/ AVIATION... STRATUS DECK ACROSS THE HILL COUNTRY AND ADJACENT AREAS WILL CONTINUE TO EXPAND THROUGH THE NEAR-DAYBREAK HOURS. CIG BASES WILL MOSTLY BE LOW MVFR WITH OCCASIONAL DROPS TO IFR BEFORE LIFTING/SCATTERING OUT TO VFR AROUND 15-16Z AT KAUS/KSAT/KSSF AND 17Z AT KDRT. LIGHT SFC WINDS THIS MORNING WILL BECOME SE-SLY MOSTLY AOB 10KTS THROUGH THE AFTERNOON. ISOLATED SHRA/TSRA ARE POSSIBLE ACROSS FAR WESTERN PORTIONS OF THE REGION...AS WELL AS GENERALLY EAST OF A LINE FROM KBMQ TO KHYI TO KVCT...MAINLY DURING THE AFTERNOON HOURS. HOWEVER...AREAL COVERAGE IS TOO LOW TO WARRANT EXPLICIT MENTION OF IMPACTS AT KAUS. PREV DISCUSSION... /ISSUED 359 AM CDT FRI JUL 19 2013/ SHORT TERM (TODAY THROUGH SATURDAY)... A THIN SUBTROPICAL RIDGE AXIS IS OVER SOUTH CENTRAL TEXAS BETWEEN A TUTT LOW OVER THE CENTRAL GULF COAST AND AN UPPER LEVEL LOW OVER SONORA STATE IN NORTHWESTERN MEXICO. AREA RADARS SHOW SCATTERED SHOWERS OVER THE SERRANIAS DEL BURRO AND ISOLATED STREAMER SHOWERS OVER THE COASTAL PLAINS. HAVE SLIGHT CHANCE POPS TODAY INTO THIS EVENING FOR OUR EASTERN COUNTIES AS THE TUTT LOW APPROACHES WHILE INTERACTING WITH THE SEABREEZE. ALSO HAVE POPS FOR OUR FAR WESTERN AREA AS SOME STORMS MAY COME OFF THE SERRANIAS DEL BURROS. ON SATURDAY...THE TUTT LOW MOVES A LITTLE FURTHER WEST TO THE UPPER TEXAS COAST/SOUTHEASTERN TEXAS TO ENHANCE THE SEABREEZE. POPS INCREASE TO LOW END CHANCE ACROSS THE EAST. HIGHS WARM SLIGHTLY TODAY AND THEN LEVEL OFF MOST AREAS OR EVEN COOL SLIGHTLY IN THE FAR EAST ON SATURDAY. LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)... THE TUTT LOW WEAKENS INTO A SHEAR AXIS OVER EASTERN INTO SOUTHERN TEXAS BY SUNDAY WHILE A SHORT-WAVE ROTATES AROUND THE SONORAN UPPER LOW TOWARD THE BIG BEND AND SLOWLY DEVELOPS INTO AN UPPER LOW ITSELF LATE SUNDAY INTO MONDAY. THE ECMWF/UKMET DEPICT THIS DEVELOPMENT OVER THE BIG BEND STRONGER WHILE THE GFS/GEM/NAVGEM ARE MUCH WEAKER OR NON EXISTENT. WILL GO WITH AN IN BETWEEN SOLUTION AND HAVE GONE WITH SLIGHT CHANCE POPS FOR ALL AREAS SUNDAY AND AGAIN MONDAY. HOWEVER...POPS MAY HAVE TO BE RAISED WITH INCREASING QPF OUT WEST IF THE STRONGER ECMWF/UKMET VERIFY. ON TUESDAY...THE SUBTROPICAL RIDGE REASSERTS ITSELF WITH SLIGHT CHANCE POPS ONLY IN THE FAR WEST. FOR THE REMAINDER OF NEXT WEEK INTO NEXT WEEKEND...THE SUBTROPICAL RIDGE DOMINATES WITH NO POPS AND ABOVE AVERAGE DAYTIME TEMPERATURES. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 73 96 74 96 75 / 20 30 20 20 10 AUSTIN BERGSTROM INTL AIRPORT 71 96 71 96 73 / 20 20 20 20 10 NEW BRAUNFELS MUNI AIRPORT 70 95 71 96 72 / 10 20 10 20 10 BURNET MUNI AIRPORT 72 94 72 94 73 / 10 20 10 20 10 DEL RIO INTL AIRPORT 74 93 74 94 76 / 10 10 10 20 10 GEORGETOWN MUNI AIRPORT 72 95 72 94 73 / 20 30 20 20 10 HONDO MUNI AIRPORT 71 96 73 96 74 / 10 10 10 20 10 SAN MARCOS MUNI AIRPORT 71 95 72 96 74 / 20 20 10 20 10 LA GRANGE - FAYETTE REGIONAL 73 95 73 95 76 / 20 30 20 30 10 SAN ANTONIO INTL AIRPORT 74 95 74 95 76 / 10 20 10 20 10 STINSON MUNI AIRPORT 73 95 73 96 74 / 10 20 10 20 10 && .EWX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE/AVIATION...13 SYNOPTIC/GRIDS...02 PUBLIC SERVICE/DATA COLLECTION...30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1155 PM CDT THU JUL 18 2013 .DISCUSSION... SEE THE 06Z AVIATION DISCUSSION BELOW. 40 && .AVIATION... NOT MUCH CHANGE FROM THE PREVIOUS DISCUSSION AT 00Z. VFR CONDITIONS EXPECTED FOR MOST LOCATIONS FROM KCXO SOUTH TO THE COAST...WITH THE EXCEPTION AT KUTS TOWARD SUNRISE. ANY SHOWERS OR THUNDERSTORMS THAT DO DEVELOP SHOULD DISSIPATE BY EARLY FRIDAY EVENING. 40 && .PREV DISCUSSION... /ISSUED 858 PM CDT THU JUL 18 2013/ UPDATE... SEE EVENING UPDATE. DISCUSSION... A VARIETY OF CONDITIONS ACROSS SE TX THIS EVENING. SFC DEW POINTS VARY WILDLY ACROSS THE AREA WITH MID 50S OVER THE EXTREME NW ZONES...MID TO UPPER 60S CENTRAL AND LOWER TO MID 70S ALONG THE COAST AND OVER THE NORTHEAST. CONVECTION OVER THE CWA HAS WANED AND THE STORMS TO THE EAST ALSO SHOWS SIGNS OF WEAKENING. THE LATEST RAP SUPPORTS OTHER SHORT TERM MODELS WITH CONVECTION GENERALLY ENDING WITH POSSIBLE REDEVELOPMENT ALONG THE COAST PRIOR TO SUNRISE. 00Z SOUNDINGS SHOW PW VALUES NEAR 1.9 INCHES AND 1.7 INCHES AT CRP. 850 MB MOISTURE WAS HIGHER OVER LOUISIANA AND DRIER TOWARD THE MIDDLE AND LOWER TEXAS COAST. A WEAK 850 MB LOW WAS LOCATED OVER EASTERN LOUISIANA WITH A WEAKNESS ALOFT ALSO OVER EASTERN LA. THIS WEAKNESS IS PROGGED TO SHIFT WEST ON FRIDAY AND WILL PROBABLY BRING THE EASTERN HALF OF THE AREA SLIGHTLY HIGHER RAIN CHANCES. WILL ISSUE NEW ZONES TO CLEAN UP EVENING WORDING ONCE THE THREAT FOR CONVECTION ENDS. 43 PREV DISCUSSION... /ISSUED 647 PM CDT THU JUL 18 2013/ DISCUSSION... SEE THE 00Z AVIATION DISCUSSION BELOW. 40 AVIATION... THE MAIN WEATHER FEATURES AFFECTING SE TX AT 2330Z THIS EVENING WERE THE SURFACE HIGH PRESSURE RIDGE EXTENDING INTO THE AREA FROM KY AND WHAT LOOKED TO BE A TUTT LOW INLAND OF THE FL AND AL COASTS. THE DRY MID AND UPPER LEVEL AIRMASS THAT WAS OVER THE AREA EARLIER TODAY WAS PUSHING OFF TO THE SOUTHWEST. ISOLATED SHOWERS WILL LIKELY AFFECT AT LEAST KUTS AND KCLL THROUGH ABOUT 02Z OR SO. THESE MAY DEVELOP A BIT FURTHER TO THE SOUTH AND WILL AMEND IF NECESSARY. OTHER STORMS OVER WESTERN LA SHOULD DISSIPATE AFTER SUNSET. ALTHOUGH THERE MAY BE ANOTHER ISOLATED EPISODE OF A SITE EXPERIENCING IFR OR LOWER LATE TONIGHT OR EARLY FRIDAY MORNING... EXPECT MOST LOCATIONS TO REMAIN VFR THROUGH THE NIGHT AND ON FRIDAY. WENT WITH MVFR FOR KUTS AND KCXO BUT THESE CONDITIONS COULD ALSO AFFECT KLBX AS WELL. FOR THE MOST PART...FELT THAT AS THE UPPER LOW MOVES WESTWARD THAT SE TX SHOULD BE IN THE RELATIVELY DRIER SIDE OF THE SYSTEM THROUGH MIDDAY. THE EXCEPTIONS SHOULD BE THOSE LOCATIONS NEAR AND ALONG THE COAST IF ISOLATED SHOWERS DEVELOP OFF THE COAST AND MOVE INLAND DURING THE MORNING. THE NAM12 WAS MORE AGGRESSIVE TOMORROW AFTERNOON AND FELT THAT THE CHANCES WERE HIGH ENOUGH GIVEN THAT ANY MOISTURE WRAPPING AROUND THE UPPER LOW SHOULD HELP ENHANCE THE SEABREEZE OR THE LIFT PROVIDED BY THE UPPER LEVEL SYSTEM. FOR NOW WILL END THE RAIN CHANCES NEAR THE COAST AND GO WITH A VCSH DURING THE LATTER HALF OF THE AFTERNOON FOR MOST INLAND SITES NEAR THE METRO HOUSTON AIRPORTS. 40 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 93 72 94 73 / 20 20 20 30 10 HOUSTON (IAH) 75 93 73 93 73 / 20 30 20 30 20 GALVESTON (GLS) 79 90 79 89 78 / 20 30 20 30 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...43 AVIATION/MARINE...40
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1011 PM CDT SAT JUL 20 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 247 PM CDT SAT JUL 20 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SECONDARY COLD FRONT STRETCHING FROM CENTRAL NORTH DAKOTA TO PORT WASHINGTON TO SOUTHERN LOWER MICHIGAN. SEVERAL SHORTWAVES NOTED ON WV IMAGERY FROM WESTERN WISCONSIN TO NORTH DAKOTA. THE SHORTWAVE OVER WESTERN WISCONSIN MAY BE HELPING A FEW SHOWERS POP JUST WEST OF THE FOX VALLEY THIS AFTERNOON EVEN WITHOUT MUCH INSTABILITY AND NORTH OF THE FRONTAL BOUNDARY. WILL KEEP AN ISOLATED POP MENTION OVER NORTHEAST WISCONSIN FOR THE REST OF THE AFTERNOON. PRETTY QUIET UPSTREAM UNTIL YOU REACH THE DAKOTAS. WITH SEVERAL SHORTWAVES TO PASS OVER THE REGION...SMALL PRECIP CHANCES ARE THE MAIN FORECAST CONCERN. TONIGHT...LAST NIGHTS COLD FRONT WILL SETTLE FROM THE NORTHERN PLAINS TO FAR NORTHEAST ILLINOIS. THE 850MB FRONT WILL STALL FARTHER NORTH OVER CENTRAL WISCONSIN WHERE SEVERAL WEAK RIPPLES UPSTREAM WILL PASS OVER WITHIN WNW FLOW ALOFT. WEAK FGEN ALSO NOTED ALONG THE FRONT IN THE MODELS...BUT MODELS ARE ALSO VERY GENEROUS IN CREATING QPF ALONG THE FRONT TODAY...WHICH HAS NOT VERIFIED WELL. GIVEN VERY WEAK FORCING AND LITTLE TO NO INSTABILITY TONIGHT...AM NOT ENTHUSIASTIC ABOUT PRECIP CHANCES AND WILL LEAVE THE FORECAST AREA DRY TONIGHT EXCEPT FOR VERY LATE WHEN A FEW SPRINKLES OR LIGHT SHOWERS ARE POSSIBLE OVER CENTRAL WISCONSIN WHERE MOISTURE GETS A LITTLE MORE DEEPER THAN THE REST OF THE AREA. PLENTY OF MID CLOUDS UPSTREAM SO INCREASED SKY COVER...AND THEREFORE MIN TEMPS AS WELL. LOWS FROM THE MID 40S NORTH TO UPPER 50S SOUTH. SUNDAY...A LITTLE STRONGER SHORTWAVE WILL SWING ACROSS THE NORTHERN MISSISSIPPI VALLEY AND INTO SOUTHWEST WISCONSIN IN THE AFTERNOON. FORCING WILL REMAIN ON THE WEAKER SIDE...BUT WILL IMPROVE MARGINALLY THROUGH THE DAY WITH THE APPROACH OF THE SHORTWAVE. WILL KEEP POPS WEST OF THE FOX VALLEY AND INCREASE THEM A BIT OVER CENTRAL WISCONSIN FOR THE AFTERNOON. IF SUFFICIENT BREAKS IN THE CLOUDS OCCUR SO TEMPS CAN REACH INTO THE MID 70S...CAPES MAY REACH INTO THE 500-700 J/KG RANGE OVER CENTRAL. SO CANNOT RULE OUT THUNDER CONSIDERING THUNDERSTORMS ARE OCCURRING UPSTREAM OVER THE PLAINS. HIGHS IN THE LOW TO MID 70S UNDER PARTLY TO MOSTLY CLOUDY CONDITIONS. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 247 PM CDT SAT JUL 20 2013 AREA REMAINS UNDER NW UPPER FLOW DURING THE PERIOD AS SHORTWAVE TROFS MOVE THROUGH MEAN LONGWAVE TROF OVER E NOAM. STRONGEST OF THE SHORTWAVES MOVES THROUGH LATE MONDAY. SUFFICIENT INSTABILITY AND SHEAR FOR THUNDERSTORMS WITH GUSTY WINDS AHEAD OF ASSOCIATED COLD FRONT LATE MONDAY INTO MONDAY EVENING. BIGGEST QUESTION IS AMOUNT OF PRECIP IN WAA AHEAD OF THAT SYSTEM. GFS A BIT MORE AGRESSIVE WITH ELEVATED INSTABILITY AND APPEARS TO SUFFER FROM SOME CONVECTIVE FEEDBACK OVER S WISC LATE SUNDAY. REGARDLESS... SCATTERED SHOWERS OR STORMS EXPECTED LATE SUNDAY ASSOCIATED WITH LIFT IN WAA ZONE. COOL AIR MOVES INTO REGION BEHIND THE LATE MONDAY COLD FRONT...WITH LOW TEMPS BY TUE NIGHT FALLING WELL INTO THE 40S ACROSS THE FAR NORTH. WENT BELOW GUIDANCE MINS FOR THE PERIOD. TEMP FORECAST FOR THE REMAINDER OF THE PERIOD A BLEND OF BEST PERFORMING MODEL GUIDANCE. OUTSIDE OF TUE MAX TEMPS...MUCH OF PERIOD WILL HAVE TEMPS AOB NORMS. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1011 PM CDT SAT JUL 20 2013 MID LEVEL VFR CLOUDS WILL CONTINUE TO PASS OVER THE AREA TONIGHT INTO SUNDAY ALONG AND NEAR STATIONARY FRONTAL BOUNDARY. PATCHY MVFR CIGS WITH LIGHT RAIN MAY DEVELOP OVER CENTRAL WISCONSIN OVERNIGHT AND THEN LATER SUNDAY OVER THE REST OF THE AREA. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......JKL AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
507 PM CDT FRI JUL 19 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 204 PM CDT FRI JUL 19 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A LINE OF CLOUDS EXTENDING FROM A PRE-FRONTAL TROUGH FROM LOWER MICHIGAN TO NEBRASKA...WHICH EXITED THE AREA EARLIER THIS MORNING. THE MAIN FOCUS CENTERS AROUND A COLD FRONT WHICH EXTENDS FROM WAUSAUKEE TO MINNEAPOLIS. A LINE OF BUBBLY CU CONTINUES TO FIRE ALONG THE FRONT...THOUGH CONVECTION IS WIDELY SCT AT BEST. DID HAVE ONE STRONG STORM DEVELOP OVER THE SOUTHERN U.P. EARLIER THIS AFTERNOON...BUT THE OTHER STORMS HAVE BEEN GARDEN VARIETY. GUSTY WEST WINDS HAVE HELPED MIX DOWN DRIER AIR ALOFT OVER NORTH-CENTRAL AND CENTRAL WISCONSIN...WHICH HAS KEPT THE INSTABILITY IN CHECK OVER THESE AREAS. DEWPOINTS REMAIN IN THE LOW 70S FROM THE SOUTHERN FOX VALLEY TO THE WEST SHORE OF THE BAY OF GREEN BAY WHERE ML CAPES ARE UPWARDS OF 1.6K J/KG. DEWPOINTS HAVE BEEN FALLING JUST UPSTREAM OF THE FOX VALLEY AT SHAWANO AND WAUPACA...SO THINK THIS TREND WILL MOVE TO LOCATIONS FURTHER EAST. AS RESULT...THINK CHANCES OF SEVERE STORMS DEVELOPING IS RELATIVELY LOW AND WILL JUST CARRY A SLIGHT CHANCE OF STORMS FOR THE REST OF THE AFTERNOON. AS FOR THE HEAT ADVISORY...SOME LOCATIONS FLIRTING WITH CRITERIA...BUT IN GENERAL...HEAT INDEX READINGS ARE BELOW 95F. WITH DEWPOINTS FALLING DUE TO MIXING...WILL CANCEL THE ADVISORY WITH THE AFTERNOON FORECAST PACKAGE. TONIGHT...ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR THE FIRST COUPLE HOURS OF THE EVENING. THE THREAT OF PRECIP WILL DIMINISH QUICKLY BY MID-EVENING...AND DRIER AIR WILL GRADUALLY FILTER SOUTHEAST ACROSS THE REGION. THE MAIN PUSH OF COOLER AND DRIER AIR WILL NOT ARRIVE UNTIL LATE TONIGHT WHEN A SECONDARY FRONT SHIFTS SOUTH ACROSS THE NORTHERN THIRD OF THE STATE. UNTIL THAT FRONT ARRIVES...THINK WILL SEE MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS. LOWS RANGING FROM THE MIDDLE 50S NORTH TO THE MIDDLE 60S SOUTH. SATURDAY...THE SECONDARY COLD FRONT WILL CONTINUE MOVE SOUTH ACROSS CENTRAL WISCONSIN EARLY IN THE PERIOD AND THEN SETTLE OVER THE SOUTHERN GREAT LAKES IN THE AFTERNOON. RIGHT REAR QUAD OF JET STREAK WILL SWING FROM WEST-CENTRAL WISCONSIN TO SOUTHEAST WISCONSIN BUT THE DEEPER MOISTURE WILL BE TIED UP ALONG THE COLD FRONT SO CENTRAL WISCONSIN MAY JUST SEE A LITTLE MORE CU THAT THE REST OF THE REGION. OTHERWISE...LIGHT NORTH WINDS WILL USHER IN DEWPOINTS IN THE MID 40S TO MID 50S...WITH HIGHS MAINLY RANGING THROUGH THE 70S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 204 PM CDT FRI JUL 19 2013 UPPER PATTERN THIS PERIOD CHARACTERIZED BY MEAN TROF IN THE EAST WITH RIDGE OVER THE WEST. RIDGE EXPECTED TO BUILD SOME OVER ROCKIES LATER IN PERIOD. TIMING ISSUES LATER PERIODS CONTINUE WITH MODELS...THOUGH TREND IS TOWARD HIGHEST PROBABILITY OF PCPN MON/MON NIGHT. OP GFS COOLER AT END OF PERIOD THAN THAT SUGGESTED BY 00Z ECMWF...THOUGH CURRENT ENSEMBLES FROM BOTH GFS AND ECMWF TREND CLOSER TO GFS SOLUTION. HAVE STAYED WITH BLEND OF MODELS FOR LATER PERIODS. IN NEAR TERM...SFC HIGH TO SHIFT EAST WITH WARM FRONT MOVING INTO SOUTHWEST WI SAT NIGHT. GIVEN LINGERING DRY AIR MASS WILL STAY WITH INHERITED DRY FORECAST. WAA REGIME CONTINUES SUN INTO MONDAY AHEAD OF FRONT EXPECTED TO MOVE THROUGH LATER MONDAY. MUCH OF GULF MOISTURE TIED TO FRONT TO SOUTH OF AREA. MODELS NOT SHOWING MUCH IN THE WAY OF INSTABILITY...SOME WEAK ELEVATED INSTABILITY PRESENT. WENT MORE WITH SHOWERS...ISOLATED THUNDER AT BEST. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 507 PM CDT FRI JUL 19 2013 A COLD FRONT WILL CONTINUE TO SLIDE SOUTH OVER THE SOUTHEAST HALF OF WISCONSIN THIS EVENING. ISOLATED SHOWERS OR STORMS WILL LINGER THROUGH EARLY EVENING OVER EAST CENTRAL WISCONSIN. COOLER AND DRIER AIR WILL FILTER INTO THE REGION ON NORTHWEST WINDS GUSTING TO 20 KNOTS EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED TONIGHT INTO SATURDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
330 PM CDT FRI JUL 19 2013 .SHORT TERM... LATE THIS AFTERNOON...TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH. MAIN ISSUE WILL BE AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS AS COLD FRONT SLIDES SOUTHEAST THROUGH THE AREA THROUGH EARLY THIS EVENING. CUMULUS LINE FORMING ALONG FRONT TO THE NORTHWEST OF THE FORECAST AREA. UPWARD VERTICAL MOTION IS WEAK TO MODEST WITH FRONT AS IT PASSES THROUGH THE AREA...WITH WEAK TO MODEST 500MB VORTICITY MAXIMUM TRAILING THE FRONT. CAP ALMOST MIXED OUT IN SOUTHEAST COUNTIES WITH LOWER TO MID 90S TEMPERATURES...WITH SLIGHTLY COOLER TEMPERATURES ALLOWING FOR A BIT MORE CAPPING TO THE NORTHWEST. LATEST HRRR/WRF 4KM WITH LAPS AGREE ON A BROKEN LINE OF SHOWERS AND THUNDERSTORMS MOVING THROUGH THE AREA WITH THE FRONT. BEST CHANCES PROBABLY WILL BE IN THE FAR EAST AND OVER LAKE MICHIGAN...AS FRONT INTERACTS WITH COOL LAKE AIRMASS AND RESULTS IN ENHANCED UPWARD VERTICAL MOTION. WENT WITH SCATTERED POPS IN FORECAST THROUGH EARLY EVENING FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA...AS THERE IS SOME UNCERTAINTY WITH THE AREAL COVERAGE GIVEN THE WEAK TO MODEST UPWARD VERTICAL MOTION. SPC HAS MAINLY THE SOUTHEAST HALF OF THE AREA IN SLIGHT RISK FOR SEVERE STORMS THROUGH EARLY EVENING. RAP AREA FORECAST SOUNDINGS INDICATE AROUND 2500 J/KG MEAN LAYER CAPE WITH AROUND 30 KNOTS OF 0 TO 6 KM SHEAR AND FAIRLY HIGH PRECIPITABLE WATER VALUES. THIS SHOULD ALLOW FOR SOME STRONG TO SEVERE STORMS TO DEVELOP. DAMAGING WINDS AND LARGE HAIL WOULD BE THE MAIN HAZARDS. KEPT HEAT ADVISORY GOING UNTIL 00Z SATURDAY ACROSS THE AREA...DESPITE MIXY CONDITIONS KEEPING DEW POINTS IN THE 60S IN PORTIONS OF THE AREA. HEAT INDEX VALUES WILL STILL BE IN THE 95 TO 102 RANGE. COLD AIR ADVECTION THEN BRINGS COOLER AND DRIER AIRMASS INTO THE REGION BEHIND FRONT FROM MID EVENING THROUGH SATURDAY...AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTHWEST. BACKDOOR COLD FRONT DOES SLIDE SOUTHWARD THROUGH THE AREA SATURDAY...FIRST DOWN THE LAKESHORE THEN IN THE WEST LATER IN THE DAY. NORTHEAST WINDS AFTER THE FRONTAL PASSAGE WILL BRING COOLER TEMPERATURES...ESPECIALLY NEAR THE LAKE. KEPT DRY FORECAST AS AIRMASS IS FAIRLY DRY DESPITE WEAK INSTABILITY IN FORECAST SOUNDINGS. SATURDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM WEAK VORTICITY MAXIMUMS WITHIN NW FLOW ALOFT WILL MOVE ACROSS THE REGION DURING THIS PERIOD. A SLIGHTLY MORE ORGANIZED SHORTWAVE TROUGH WILL PASS THROUGH IA...IL...AND SRN WI FOR SUNDAY AFTERNOON THROUGH THE NIGHT BUT LOOKS THE MOST ORGANIZED TO THE SOUTH. PWS HOWEVER COULD INCREASE TO 1.5 INCHES WITH THIS FEATURE. MAINTAINING CHANCE POPS FOR THIS BUT IF UPPER WAVE BECOMES STRONGER WITH GIVEN MOISTURE...THEN RAIN COVERAGE AND INTENSITY WOULD BE HIGHER. WITH MORE HUMID CONDITIONS RETURNING AND SCT-BKN CLOUD COVER...KEPT MILD LOW TEMPS FOR THIS PERIOD. ONSHORE FLOW WILL KEEP FAR ERN WI RELATIVELY COOL FOR SAT BUT INLAND TEMPS MORE CHALLENGING. DID ACCOUNT FOR SOME SUNSHINE IN HIGHS FOR SAT. SUBSIDENCE FROM DEPARTING SHORTWAVE TROUGH FOR MON SHOULD RESULT IN MORE SUNSHINE. IN ADDITION...SSWLY WINDS AND WEAK WARM ADVECTION AHEAD OF LOW PRESSURE TRACKING ACROSS SRN CANADA SHOULD ALSO HELP BOOST HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. ONLY A SLIGHT CHANCE OF TSTORMS IS FORECAST TO ACCOUNT FOR SLOWER SHORTWAVE TROUGH MOVEMENT OR A FASTER MOVEMENT OF THE COLD FRONT THAT EXTENDS FROM THE CANADIAN LOW. LOW POPS ARE THEN FORECAST FOR THE COOL FROPA MON NT AND TUE. .LONG TERM... WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM EXTENDED MODELS DUE SHOW A MORE ORGANIZED SFC HIGH PRESSURE AREA TO COME INTO THE GREAT LAKES REGION FOR WED AND THU AND POSSIBLY EXTENDING THROUGH FRI. WENT DRY WITH THE EXCEPTION OF THE FAR WRN CWA FOR FRI. PLEASANT WITH NEAR NORMAL TEMPS AND HUMIDITY EXPECTED. && .AVIATION/00Z TAFS/...VFR CONDITIONS ARE EXPECTED ACROSS TAF SITES TONIGHT AND SATURDAY. GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED UNTIL SUNSET...WITH FREQUENT GUSTS IN THE 20 TO 25 KNOT RANGE. SOME DIURNAL CUMULUS WILL DEVELOP AS MID LEVEL CLOUDS MOVE THROUGH AND EAST OF THE AREA. SCATTERED SHOWERS AND STORMS ARE EXPECTED WITH THE COLD FRONTAL PASSAGE LATER THIS AFTERNOON...ENDING EARLY THIS EVENING AS FRONT MOVES OUT OF THE AREA. LEFT VICINITY THUNDER WORDING IN TAFS TO ACCOUNT FOR THIS...WITH BRIEF MVFR VISIBILITIES AND GUSTY WINDS POSSIBLE IN ANY STORMS. AREAL COVERAGE IS UNCERTAIN...SO COULD END UP BEING DRY AT TAF SITES. WINDS WILL SHIFT TO THE NORTHWEST BEHIND THE FRONT BY MID EVENING...WITH SKIES CLEARING OUT TONIGHT WITH COOLER AND DRIER AIRMASS MOVING IN. WINDS WILL SHIFT NORTH AND THEN NORTHEAST BY SATURDAY AFTERNOON...AS BACKDOOR COLD FRONT MOVES SOUTHWARD THROUGH THE AREA. MOSTLY CLEAR SKIES ARE EXPECTED SATURDAY AT THE EASTERN SITES...WITH SOME DIURNAL CUMULUS AT MADISON DURING THE AFTERNOON. && .MARINE...SMALL CRAFT ADVISORY WILL CONTINUE UNTIL 00Z SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. TIGHT PRESSURE GRADIENT AND MIXING WITH DAYTIME HEATING WILL CONTINUE TO BRING GUSTY SOUTHWEST TO WEST WINDS ACROSS THIS AREA THROUGH THE REST OF THE DAY. GUSTS IN THE MID 20 KNOT RANGE ARE EXPECTED AT TIMES. OFFSHORE FLOW WILL KEEP ANY HIGH WAVES OVER THE OPEN WATERS. THE GUSTS WILL SUBSIDE BY EVENING...WITH A WEAKENING PRESSURE GRADIENT WITH THE PASSING COLD FRONT. BACKDOOR COLD FRONT WILL PUSH SOUTHWARD ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN SATURDAY MORNING...WITH A QUICK WIND SHIFT TO THE NORTHEAST BEHIND IT. WINDS MAY BE GUSTING UP TO 15 KNOTS OR SO FOR AN HOUR OR TWO AFTER THE FRONTAL PASSAGE...THEN REMAIN IN THE 10 TO 15 KNOT RANGE THROUGH THE REST OF THE DAY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR WIZ046-047-051-052- 056>060-062>072. LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LMZ643>646. && $$ TONIGHT/SATURDAY AND AVIATION/MARINE...WOOD SATURDAY NIGHT THROUGH FRIDAY...GEHRING
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 204 PM CDT FRI JUL 19 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A LINE OF CLOUDS EXTENDING FROM A PRE-FRONTAL TROUGH FROM LOWER MICHIGAN TO NEBRASKA...WHICH EXITED THE AREA EARLIER THIS MORNING. THE MAIN FOCUS CENTERS AROUND A COLD FRONT WHICH EXTENDS FROM WAUSAUKEE TO MINNEAPOLIS. A LINE OF BUBBLY CU CONTINUES TO FIRE ALONG THE FRONT...THOUGH CONVECTION IS WIDELY SCT AT BEST. DID HAVE ONE STRONG STORM DEVELOP OVER THE SOUTHERN U.P. EARLIER THIS AFTERNOON...BUT THE OTHER STORMS HAVE BEEN GARDEN VARIETY. GUSTY WEST WINDS HAVE HELPED MIX DOWN DRIER AIR ALOFT OVER NORTH-CENTRAL AND CENTRAL WISCONSIN...WHICH HAS KEPT THE INSTABILITY IN CHECK OVER THESE AREAS. DEWPOINTS REMAIN IN THE LOW 70S FROM THE SOUTHERN FOX VALLEY TO THE WEST SHORE OF THE BAY OF GREEN BAY WHERE ML CAPES ARE UPWARDS OF 1.6K J/KG. DEWPOINTS HAVE BEEN FALLING JUST UPSTREAM OF THE FOX VALLEY AT SHAWANO AND WAUPACA...SO THINK THIS TREND WILL MOVE TO LOCATIONS FURTHER EAST. AS RESULT...THINK CHANCES OF SEVERE STORMS DEVELOPING IS RELATIVELY LOW AND WILL JUST CARRY A SLIGHT CHANCE OF STORMS FOR THE REST OF THE AFTERNOON. AS FOR THE HEAT ADVISORY...SOME LOCATIONS FLIRTING WITH CRITERIA...BUT IN GENERAL...HEAT INDEX READINGS ARE BELOW 95F. WITH DEWPOINTS FALLING DUE TO MIXING...WILL CANCEL THE ADVISORY WITH THE AFTERNOON FORECAST PACKAGE. TONIGHT...ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR THE FIRST COUPLE HOURS OF THE EVENING. THE THREAT OF PRECIP WILL DIMINISH QUICKLY BY MID-EVENING...AND DRIER AIR WILL GRADUALLY FILTER SOUTHEAST ACROSS THE REGION. THE MAIN PUSH OF COOLER AND DRIER AIR WILL NOT ARRIVE UNTIL LATE TONIGHT WHEN A SECONDARY FRONT SHIFTS SOUTH ACROSS THE NORTHERN THIRD OF THE STATE. UNTIL THAT FRONT ARRIVES...THINK WILL SEE MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS. LOWS RANGING FROM THE MIDDLE 50S NORTH TO THE MIDDLE 60S SOUTH. SATURDAY...THE SECONDARY COLD FRONT WILL CONTINUE MOVE SOUTH ACROSS CENTRAL WISCONSIN EARLY IN THE PERIOD AND THEN SETTLE OVER THE SOUTHERN GREAT LAKES IN THE AFTERNOON. RIGHT REAR QUAD OF JET STREAK WILL SWING FROM WEST-CENTRAL WISCONSIN TO SOUTHEAST WISCONSIN BUT THE DEEPER MOISTURE WILL BE TIED UP ALONG THE COLD FRONT SO CENTRAL WISCONSIN MAY JUST SEE A LITTLE MORE CU THAT THE REST OF THE REGION. OTHERWISE...LIGHT NORTH WINDS WILL USHER IN DEWPOINTS IN THE MID 40S TO MID 50S...WITH HIGHS MAINLY RANGING THROUGH THE 70S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 204 PM CDT FRI JUL 19 2013 UPPER PATTERN THIS PERIOD CHARACTERIZED BY MEAN TROF IN THE EAST WITH RIDGE OVER THE WEST. RIDGE EXPECTED TO BUILD SOME OVER ROCKIES LATER IN PERIOD. TIMING ISSUES LATER PERIODS CONTINUE WITH MODELS...THOUGH TREND IS TOWARD HIGHEST PROBABILITY OF PCPN MON/MON NIGHT. OP GFS COOLER AT END OF PERIOD THAN THAT SUGGESTED BY 00Z ECMWF...THOUGH CURRENT ENSEMBLES FROM BOTH GFS AND ECMWF TREND CLOSER TO GFS SOLUTION. HAVE STAYED WITH BLEND OF MODELS FOR LATER PERIODS. IN NEAR TERM...SFC HIGH TO SHIFT EAST WITH WARM FRONT MOVING INTO SOUTHWEST WI SAT NIGHT. GIVEN LINGERING DRY AIR MASS WILL STAY WITH INHERITED DRY FORECAST. WAA REGIME CONTINUES SUN INTO MONDAY AHEAD OF FRONT EXPECTED TO MOVE THROUGH LATER MONDAY. MUCH OF GULF MOISTURE TIED TO FRONT TO SOUTH OF AREA. MODELS NOT SHOWING MUCH IN THE WAY OF INSTABILITY...SOME WEAK ELEVATED INSTABILITY PRESENT. WENT MORE WITH SHOWERS...ISOLATED THUNDER AT BEST. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1233 PM CDT FRI JUL 19 2013 A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL AND NORTHEAST WISCONSIN THIS AFTERNOON. STORMS HAVE FIRED ALONG THE FRONT OVER FAR NORTHERN WISCONSIN AND THE UPPER PENINSULA BUT MIXING OF DRIER AIR TO THE SURFACE HAS LIMITED THE STORMS INTENSITY. ADDITIONAL STORMS ARE EXPECTED TO FIRE THIS AFTERNOON AND SOME COULD PRODUCE STRONG GUSTY WINDS. CLEARING IS EXPECTED BEHIND THE COLD FRONT THIS EVENING WITH GOOD FLYING WEATHER TONIGHT THROUGH SATURDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1203 PM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT FRI JUL 19 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER RIDGING OVER THE WESTERN U.S. AS WELL AS OVER THE MID-ATLANTIC...WHILE TROUGHING WAS IN-BETWEEN FROM SOUTH CENTRAL CANADA INTO WESTERN MN. THIS TROUGHING IS COMPOSED OF A POTENT SHORTWAVE OVER MANITOBA...A SHORTWAVE FROM CENTRAL NORTH DAKOTA INTO NORTHERN MN...AND A DEEP DRY-SLOT AHEAD OF THE SHORTWAVE FROM SOUTH DAKOTA INTO WESTERN LAKE SUPERIOR. A COLD FRONT AT THE SURFACE WAS ANALYZED FROM NEAR SIOUX FALLS TO THUNDER BAY ONTARIO...SLIGHTLY AHEAD OF THE DRY SLOT. AMAZINGLY...DESPITE 4000 J/KG OF SBCAPE AND LITTLE CIN ON THE 00Z ABR SOUNDING...THE FRONT WENT THROUGH THERE WITH LITTLE ACTIVITY. BEST GUESS WAS THE LACK OF CONVERGENCE ON THE FRONT...WHICH WAS REPRESENTED WELL ON 0-2KM RAP CONVERGENCE PLOTS. FRONT IS MORE ACTIVE NOW...MORESO THE WARM ADVECTION AHEAD OF IT...WITH HIGHER BASED SHOWERS AND THUNDERSTORMS FROM FARMINGTON MN TO PARK FALLS WI. WARM AIR CONTINUES TO HOLD STRONG IN THE WARM SECTOR WITH READINGS IN THE UPPER 70S / LOW 80S...THANKS IN PART TO A 30-45 KT 925MB WINDS OVER THE AREA. THERE IS EVEN WARMER AIR FLOWING IN FROM THE WEST ALONG THE FRONT...OBSERVED ON THE 00Z ABR SOUNDING WITH AN 800MB TEMP OF 20C AND 925MB TEMP OF 30C...COMPARED TO 17C AND 27C RESPECTIVELY FROM THE 00Z MPX SOUNDING. BEHIND THE FRONT...925MB TEMPS ARE NOT THAT MUCH COOLER WITH 28C OBSERVED AT GGW...BUT DEWPOINTS DROP INTO THE 50S AND LOW 60S. SYNOPTIC OVERVIEW... UPPER TROUGHING IS STILL POISED TO FORM OVER THE WESTERN GREAT LAKES REGION BY 06Z TONIGHT...THOUGH THE MORE POTENT SHORTWAVE COMPOSING THE TROUGH IS FORECAST TO STAY UP IN CANADA. MEANWHILE...THE SHORTWAVE SEEN UP IN CENTRAL NORTH DAKOTA IS SLATED TO DROP INTO CENTRAL MN BY 18Z...THEN PUSH EAST INTO LOWER MI. WITH THE UPPER TROUGHING FORMING...EXPECT THE COLD FRONT TO CONTINUE MARCHING SOUTHEAST. MODEL TIMING IS WELL AGREED UPON...AT 18Z STRETCHING FROM OMAHA NEB TO VOLK FIELD WI AND MARINETTE WI...AND AT 00Z FROM NORTHWEST MO TO NEAR DUBUQUE IA AND UP TO MANITOWOC WI. HAZARDS... ONGOING HEAT ADVISORY...DUE TO FRONTAL TIMING AND DRYING DEWPOINTS BEHIND THE FRONT...HAVE CANCELLED SOME OF THE ADVISORY. AREAS INCLUDE SOUTHEAST MN AND PORTIONS OF NORTHEAST IOWA INTO CENTRAL WI. THERE ALSO IS A CHANCE FOR SEVERE WEATHER THIS AFTERNOON ALONG THE COLD FRONT COMING THROUGH NORTHEAST IOWA AND SOUTHWEST WI. 0-6KM SHEAR VALUES ARE HIGHER IN THE 09.00Z NAM...ORDER OF 30-40 KT VERSUS 20-30 KT IN THE 09.06Z RAP. IF SEVERE WEATHER OCCURS...DAMAGING WINDS WOULD BE THE MAIN HAZARDS. TODAY... TWO BIG QUESTIONS...TEMPERATURES AND PRECIPITATION CHANCES. ON THE PRECIPITATION SIDE OF THINGS...19.00Z GFS/NAM/REGIONAL CANADIAN ALL WANT TO BRING THE SHOWERS AND SOME THUNDERSTORMS THROUGH THE FORECAST AREA THIS MORNING PRIOR TO THE FRONTAL PASSAGE. THESE ORIGINATE FROM ISENTROPIC LIFT ON THE 310 K SURFACE AHEAD OF THE FRONT. IT APPEARS THESE SHOULD WEAKEN THROUGH THE MORNING TOO WITH THE NOCTURNAL LOW LEVEL JET WEAKENING. A PERIOD OF CLEARING THEN TAKES PLACE IN THE WARM SECTOR...WITH SOME HINTS FROM THE 19.00Z GFS/REGIONAL CANADIAN AND 19.06Z RAP THAT THE FRONT COULD CONVECT IN SOUTHEASTERN PORTION OF THE FORECAST AREA SAY BETWEEN 19-23Z. NOT THRILLED ABOUT THE FRONT CONVECTING AS THE 0-2KM CONVERGENCE IS VERY WEAK. HOWEVER...GIVEN MODELS HAVE BEEN SHOWING IT THE PAST FEW DAYS AND PLENTY OF INSTABILITY PROGGED TO DEVELOP TODAY...KEPT SOME CHANCES IN THE FORECAST. HAVE ALSO ADDED SOME LOW CHANCES OF PRECIPITATION FOR THE AFTERNOON HOURS FROM TAYLOR COUNTY SOUTH TO JACKSON. HERE ANOTHER FRONT LURKING UP IN NORTHERN MN IS PROGGED BY THE 09.06Z RAP AND 09.05Z HRRR TO COME THROUGH AND HAVE SOME CONVECTION ON IT. ON THE TEMPERATURE SIDE OF THINGS...A WARM START PLUS 925MB TEMPS HOLDING IN THE 24-26C RANGE SHOULD EASILY ALLOWS HIGHS TO REACH THE UPPER 80S TO POSSIBLY MID 90S AGAIN. THIS IS EVEN DESPITE THE FRONTAL PASSAGE GIVEN THE WARM AIR STILL HOLDING BACK AND LIKELY DEEPER MIXING BEHIND THE FRONT. HOWEVER...HEAT INDICES WILL FALL WITH THE FRONT AS DRIER DEWPOINTS FLOW IN. TONIGHT... SUBSIDENCE AND DRYING COMING IN BEHIND THE COLD FRONT WILL ALLOW FOR A MOSTLY CLEAR NIGHT ACROSS THE FORECAST AREA. DRIER AIR AND DIMINISHING WINDS SHOULD ALLOW TEMPERATURES TO FALL CLOSE TO GUIDANCE VALUES...IN THE UPPER 50S TO MID 60S...10-15 DEGREES COLDER THAN TONIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 321 AM CDT FRI JUL 19 2013 SYNOPTIC OVERVIEW... MUCH OF THE NEXT 6 DAYS LOOKS TO BE DOMINATED BY NORTHWEST FLOW ACCORDING TO THE 19.00Z ECMWF/GFS/CANADIAN WITH RIDGING STAYING PUT OVER THE WESTERN U.S.. THERE ARE SOME SIGNS FROM THE ECMWF THE RIDGE MAY WANT TO BUILD EAST TOWARDS THE FORECAST AREA ON THURSDAY...BUT PLENTY OF UNCERTAINTY ON THAT SEEING THE TROUGHING IN THE GFS. ADDITIONALLY...THIS NORTHWEST FLOW HAS UNCERTAINTY IN TERMS OF TIMING SHORTWAVES AND THE CHANCES OF PRECIPITATION WITH THEM. SATURDAY THROUGH SUNDAY NIGHT... MAIN FEATURE OF INTEREST DURING THIS PERIOD IS A SHORTWAVE ALL MODELS HAVE TRACKING OUT OF MONTANA ON SATURDAY AND THROUGH THE FORECAST AREA ON SUNDAY. SURPRISINGLY MODELS ARE IN REALLY GOOD AGREEMENT WITH THIS SHORTWAVE...ALBEIT PERHAPS THE GFS HAS A BIT OF CONVECTIVE FEEDBACK TO IT. IN ANY EVENT...INCREASING 310 K ISENTROPIC LIFT COMBINED WITH INSTABILITY SHOULD INITIATE CONVECTION OVER EASTERN SOUTH DAKOTA DURING THE AFTERNOON. THIS CONVECTION THEN SPREADS TOWARDS THE FORECAST AREA SATURDAY NIGHT AS THE ISENTROPIC LIFT AND 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE SHIFTS EAST. PERHAPS THERE IS A SHOT SOME HIGH BASED SHOWERS COULD DEVELOP DOWNSTREAM OF THE CONVECTION SATURDAY AFTERNOON...BUT THINK THE BULK OF THE PRECIPITATION WOULD WAIT UNTIL SATURDAY NIGHT. SUNDAY APPEARS TO HAVE THE HIGHEST CHANCE OF RAIN WHERE DPVA ACCOMPANYING THE SHORTWAVE INTERSECTS 850MB MOISTURE TRANSPORT CONTINUING TO AIM AT THE AREA. ITS HARD TO SAY HOW SUNDAY NIGHT WILL EVOLVE. SUBSIDENCE BEHIND THE SHORTWAVE MOVING THROUGH ON SUNDAY WOULD SEEM TO LIKELY PROVIDE A DRY PERIOD...LIKE SUGGESTED BY THE 19.00Z NAM. HOWEVER... THE 19.00Z GFS/ECMWF SHOW A POTENT SHORTWAVE TROUGH CROSSING SOUTHERN MANITOBA SUNDAY NIGHT...WHICH INCREASES 850MB MOISTURE TRANSPORT INTO THE AREA. THEREFORE...THESE MODELS WANT TO HANG ONTO SOME SHOWERS. HAVE MAINTAINED SOME CHANCES OF PRECIPITATION TO ACCOUNT FOR THE GFS/ECMWF SCENARIO. BIGGEST ISSUE IN THE TEMPERATURE DEPARTMENT IS HIGHS ON SUNDAY. IF IT RAINS ALL DAY...TEMPERATURES MAY GET STUCK IN THE UPPER 60S/LOW 70S. FOR NOW TRENDED HIGHS DOWN SLIGHTLY. MONDAY THROUGH THURSDAY NIGHT... THIS PERIOD IS HIGHLY UNCERTAIN. 19.00Z GFS/ECMWF/CANADIAN SHOW NUMEROUS SHORTWAVES MOVING THROUGH THE NORTHWEST FLOW ALOFT THROUGH MUCH OF THE WEEK. TIMING AND TRACK OF THESE VARIES FROM RUN TO RUN...THUS THE LOW CONFIDENCE. THERE DOES APPEAR TO BE SOME SIGNAL FOR A COLD FRONT COMING THROUGH THE FORECAST AREA MONDAY NIGHT...ASSOCIATED WITH THAT POTENT TROUGH OVER SOUTHERN MANITOBA PROGGED TO LIFT EAST-NORTHEAST. IF THIS STAYS CONSISENT...WE MIGHT BE ABLE TO DRY OUT TUESDAY. OTHERWISE...HAVE MAINTAINED A MODEL CONSENSUS OF 20-40 PERCENT CHANCES THROUGH THURSDAY NIGHT. LIKELY THE ENTIRE PERIOD WILL NOT BE WET...BUT HARD TO PIN POINT MUCH FOR POSSIBLE DRY PERIODS BEYOND TUESDAY. WITH A NORTHWEST FLOW IN PLACE...EXPECT A COOLER FLOW OF AIR. 850MB TEMPS ARE GENERALLY PROGGED TO DROP FROM 18-20C ON MONDAY TO 12-15C FOR TUESDAY THROUGH THURSDAY. THESE SHOULD RESULT IN A DROP IN HIGHS TO SLIGHTLY BELOW NORMAL AFTER NEAR NORMAL ON MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1203 PM CDT FRI JUL 19 2013 COLD FRONT MAKING STEADY SOUTHEASTWARD PROGRESS THROUGH THE AREA. IT HAS ALREADY PASSED THROUGH KRST AND SHOULD BE THROUGH KLSE BY OR JUST AFTER 18Z. WILL THUS START BOTH SITES WITH SOME GUSTY NORTHWEST WINDS. THE WINDS EXPECTED TO DIE DOWN EARLY IN THE EVENING AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST RELAXING THE GRADIENT. NOT EXPECTING ANY FOG TO FORM OVERNIGHT AT KLSE AS THE NORTHWEST WINDS WILL BRING IN DRIER AIR WITH DEW POINTS EXPECTED TO DROP INTO THE LOWER 60S MAINTAINING A TEMP/DEW POINT SPREAD OF AT LEAST 4 DEGREES THROUGH THE NIGHT. && .CLIMATE... ISSUED AT 321 AM CDT FRI JUL 19 2013 LA CROSSE WI HAS ONLY SEEN 0.27 INCHES FOR THE MONTH OF JULY THROUGH THE 18TH. THIS IS THE 5TH DRIEST START TO JULY. THE DRIEST THROUGH JULY 18TH WAS 0.05 INCHES BACK IN 1896...AND THE LAST TIME IT WAS THIS DRY WAS IN 1967. FOR REFERENCE...LA CROSSE NORMALLY SHOULD HAVE 2.41 INCHES UP THROUGH THE 18TH. ROCHESTER MN HAS HAD QUITE A BIT MORE RAIN...THUS THE 1.42 INCHES OBSERVED THROUGH JULY 18TH IS WELL OUTSIDE THE TOP 20 DRIEST. STILL ROCHESTER IS 1.25 INCHES BELOW NORMAL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR WIZ041>044-053>055- 061. MN...NONE. IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ011-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...04 CLIMATE...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1051 AM CDT FRI JUL 19 2013 .UPDATE...THE LINE OF SHOWERS AND THUNDERSTORMS THAT WERE MOVING THROUGH WEST CENTRAL AND CENTRAL WI...AND SOUTHEAST MN EARLIER THIS MORNING HAVE ALL BUT DISSIPATED UPON MOVING SOUTHEAST INTO THE CWA AS OF 10 AM CDT. VIS SAT SHOWS CONVECTIVE DEBRIS AND MID LEVEL ACCAS ORIENTED SW TO NE MOVING SOUTHEAST THROUGH SOUTH CENTRAL AND EAST CENTRAL WISCONSIN. UPSTREAM...DIURNAL CU ALREADY DEVELOPING IN GRB AND MSP FORECAST AREAS. MAIN CHANGES WERE LIMITED TO CURRENT TRENDS AND UPDATING THE WX/POPS IN THE TODAY PERIOD. HIGHS LOOK ON TRACK AS IS. REGARDING POPS/WX THIS AFTERNOON/EVENING...ECMWF AND NAM NOT PRODUCING MUCH QPF WITH FROPA. HRRR AND LOCAL WRF FLAVOR PRODUCING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WITH FROPA...BUT NOT LARGE IN COVERAGE. ACTIVITY IS MAINLY SHOWN TO DEVELOP AFTER 20 UTC...WITH THE BULK OF THE ACTIVITY THE SOUTHEAST HALF OF THE CWA. DESTABILIZATION SHOULD BE SUFFICIENT TODAY GIVEN CURRENT CONDITIONS AND AFTER THESE CLOUDS MOVE THROUGH. LOOKING AT THE NEAR STORM ENVIRONMENT THIS AFTERNOON AND EVENING FROM THE RAP...DEEP LAYERED 0-6 KM SHEAR PEAKS AROUND 30-35 KTS...AMPLE ML CAPE INSTABILITY IS PRESENT...AND LOW-LEVEL MOISTURE WILL BE FAVORABLE WITH SFC DEW POINTS IN THE LOW 70S. AS SUCH...THE ENVIRONMENT STILL LOOKS SUPPORTIVE FOR MULTICELLS AND A FEW SUPERCELLS PROVIDED THINGS GET UNDERWAY. SPC SSEO DOESNT SHOW MUCH POTENTIAL IN REGARD TO SUPERCELLS THOUGH. ESPECIALLY WHEN LOOKING AT THE UPDRAFT HELICITY IN TERMS OF A SIGNAL THIS AFTERNOON/EVENING. ET && .AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED ACROSS TAF SITES THIS AFTERNOON...TONIGHT AND SATURDAY. GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED UNTIL SUNSET...WITH FREQUENT GUSTS IN THE 20 TO 25 KNOT RANGE. SOME DIURNAL CUMULUS WILL DEVELOP THIS AFTERNOON IN THE WAKE OF THE MID LEVEL CLOUDS NOW MOVING THROUGH THE AREA. SCATTERED SHOWERS AND STORMS ARE EXPECTED WITH THE COLD FRONTAL PASSAGE LATER THIS AFTERNOON...ENDING EARLY THIS EVENING AS FRONT MOVES OUT OF THE AREA. LEFT VICINITY THUNDER WORDING IN TAFS TO ACCOUNT FOR THIS...WITH BRIEF MVFR VISIBILITIES AND GUSTY WINDS POSSIBLE IN ANY STORMS. WINDS WILL SHIFT TO THE NORTHWEST BEHIND THE FRONT BY MID EVENING...WITH SKIES CLEARING OUT TONIGHT WITH COOLER AND DRIER AIRMASS MOVING IN. WINDS WILL SHIFT NORTH AND THEN NORTHEAST BY SATURDAY AFTERNOON...AS BACKDOOR COLD FRONT MOVES SOUTHWEST THROUGH THE AREA. MOSTLY CLEAR SKIES ARE EXPECTED SATURDAY. WOOD && .MARINE...SMALL CRAFT ADVISORY CONTINUES UNTIL 00Z SATURDAY FOR ALL OF THE NEARSHORE WATERS. TIGHT PRESSURE GRADIENT AND DAYTIME HEATING ALLOWING FOR GUSTY SOUTHWEST TO WEST WINDS ACROSS THE WATERS. THESE WINDS WILL CONTINUE THROUGH THE REST OF THE DAY...THUS HAVE EXTENDED SMALL CRAFT ADVISORY NORTH OF NORTH POINT LIGHTHOUSE UNTIL 00Z SATURDAY. WAVES WILL REMAIN WELL BELOW SMALL CRAFT ADVISORY CRITERIA WITH OFFSHORE FLOW. WINDS WILL THEN SUBSIDE EARLY THIS EVENING WITH WEAKENING PRESSURE GRADIENT AND PASSING COLD FRONT. WOOD && .PREV DISCUSSION... /ISSUED 338 AM CDT FRI JUL 19 2013/ SHORT TERM... TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM CURRENTLY WATCHING A LINE OF PRE-FRONTAL THUNDERSTORMS FROM NORTHWEST WISCONSIN THROUGH SOUTH-CENTRAL MINNESOTA. SEEMS THESE STORMS ARE HOLDING UP FAIRLY WELL RIGHT NOW...SO INCREASED MORNING POPS A BIT IN THE NORTHWEST HALF OF THE FORECAST AREA. KIND OF A TRICKY ONE THOUGH...BECAUSE MODELS ARE ALL DOING DIFFERENT THINGS WITH THIS MORNING CONVECTION...FROM WIPING IT OUT BEFORE IT ARRIVES...TO PUSHING IT ALL THE WAY THROUGH THE FORECAST AREA. THE AMOUNT OF CLOUDS/PRECIP ACROSS SRN WI THIS MORNING WILL CERTAINLY IMPACT HIGH TEMPS AND RESULTANT DESTABILIZATION FOR THE NEXT ROUND OF STORMS AS THE COLD FRONT APPROACHES. WENT WITH THE SOLUTION SEEN IN THE MOST MODELS...WHICH WOULD BRINGS THE LINE OF STORMS IN...BUT WIPES IT OUT BY THE TIME IT REACHES THE SOUTHEAST. THIS WOULD LEAVE A WINDOW OF OPPORTUNITY TO HEAT BACK UP AHEAD OF THE FRONT. GIVEN SUFFICIENT SUNSHINE...MODELS SUGGEST SURFACE BASED CAPES REACHING AROUND 3000 J/KG THIS AFTERNOON. ALSO...0-6 KM BULK SHEAR WILL BE 30-35 KT. THE BEST 850 FLOW WILL BE SET UP JUST TO THE SOUTH AND INTO MICHIGAN...ALONG WITH THE BETTER UPPER DIVERGENCE. STILL...SEEMS LIKE A DECENT SETUP FOR STRONG TO SEVERE STORMS IF THEY CAN GET GOING THIS AFTERNOON. THE NAM DOES SHOW A BIT OF A CAP THROUGH MUCH OF THE AFTERNOON WHICH COULD BE AN ISSUE. WENT WITH HIGH CHANCE POPS FOR THROUGH THE DAY DUE TO GENERAL UNCERTAINTY. MAY NEED TO RAISE MORNING POPS IN AT LEAST THE NORTHWEST THOUGH IF THE CONVECTION TO THE NORTHWEST CONTINUES TO HOLD TOGETHER. LOOKS LIKE ANOTHER HOT AND HUMID ONE TODAY AHEAD OF THE FRONT. GIVEN MORNING CLOUDS AND CONVECTION AND THEN POSSIBLE REDEVELOPMENT THIS AFTERNOON...WENT WITH HIGHS A COUPLE DEGREES LOWER THAN THE LAST COUPLE DAYS. STILL LOOKS LIKE 95-100 DEGREE HEAT INDICIES THOUGH...POSSIBLY A BIT OVER 100 IN A FEW SPOTS. WILL THUS KEEP HEAT ADVISORY GOING INTO EARLY EVENING. SHOULD TURN DRY BY LATE EVENING AS THE FRONT PUSHES THROUGH. SHOULD SEE LOWS ACTUALLY FALL INTO THE 60S MOST PLACES OVERNIGHT AS COOLER AND DRIER AIR BEGINS TO MOVE IN BEHIND THE FRONT. SATURDAY...FORECAST CONFIDENCE HIGH. A SECONDARY COLD FRONT WILL DROP DOWN THROUGH WI ON SATURDAY...WITH WINDS BECOMING NORTH. THE MODELS SHOW THE FRONT ACCELERATING DOWN THE LAKE A LITTLE FASTER THAN ON LAND AND PRODUCE LIGHT QPF ALONG THE CONVERGENCE LINE IN SOUTHEAST WI. WILL CONTINUE DRY FORECAST FOR NOW GIVEN THE WEAK FORCING. WITH MORNING SUNSHINE AND THE COLD FRONT WEAKENING AS IT GETS INTO SOUTH CENTRAL WI...HIGHS WILL BE IN THE LOWER 80S OVER MUCH OF THE AREA. THE COOL SPOT IN THE UPPER 70S WILL BE THE SHEBOYGAN AREA WHERE NORTH WINDS SHOULD PUSH INLAND EARLIER IN THE DAY. THIS WILL BE A WELCOMED RELIEF TO THE HEAT WAVE. SATURDAY NIGHT THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM. LATER SATURDAY NIGHT...THE LOW LEVEL JET WILL POINT INTO WESTERN WI ALONG WITH 850MB WARM AIR ADVECTION AND A SHORTWAVE TROUGH MOVING ACROSS THE UPPER MIDWEST. THE ELEVATED THUNDERSTORM CHANCE WILL BE HIGHER TOWARD EASTERN MN/WESTERN WI...BUT ADDED A SMALL CHANCE IN THE WESTERN MKX FORECAST AREA. THIS FAVORED AREA FOR THUNDERSTORMS IN THE VICINITY OF THE LOW LEVEL JET AND THE SHORTWAVE TROUGH WILL SHIFT EASTWARD ACROSS WI THROUGH THE DAY SUNDAY. THE NAM FOCUSES CONVECTION MORE IN NORTHERN WI ON THE NOSE OF THE LLJ WHILE THE ECMWF DIMINISHES THAT CONVECTION. THERE WILL BE ANOTHER AREA OF CONVECTION TIED MORE TOWARD THE BASE OF THE SHORTWAVE TROUGH OVER IL. THERE IS A CHANCE THAT SOUTHERN WI WILL END UP BETWEEN THE TWO AREAS OF CONVECTION. THE ECMWF IS SLOWER WITH THE 500MB TROUGH CROSSING WI...SO CHANCE OF THUNDERSTORMS CONTINUES THROUGH SUNDAY NIGHT. EITHER WAY...EXPECT PLENTY OF CLOUDS SUNDAY. ALONG WITH 925MB TEMPS ONLY AROUND 18C...HIGHS WILL BE IN THE UPPER 70S INLAND AND LOWER/MID 70S NEAR THE LAKE WITH EAST WINDS. LONG TERM... MONDAY THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM. A 500MB NORTHWEST FLOW PATTERN SETS UP OVER THE UPPER MIDWEST FOR THE FIRST HALF OF NEXT WEEK. WEAK SHORTWAVES WILL BRING THUNDERSTORM CHANCES TO SOUTHERN WI ON MONDAY. THERE IS GENERALLY AGREEMENT BETWEEN THE GFS AND ECMWF THAT A SURFACE LOW PRESSURE TROUGH WILL SWEEP SOUTHEAST THROUGH WI MONDAY NIGHT INTO TUE MORNING WITH THUNDERSTORM CHANCES ALONG THAT FRONT. WEDNESDAY THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM TO LOW. SURFACE HIGH PRESSURE IS EXPECTED OVER THE GREAT LAKES REGION ON WEDNESDAY. THEN THE GFS BRINGS THUNDERSTORMS INTO SOUTHERN WI ONCE AGAIN ON ANOTHER SHORTWAVE WHILE THE ECMWF KEEPS US HIGH AND DRY. IT WILL DEPEND ON HOW AMPLIFIED THAT EASTERN UPPER TROUGH WILL BECOME. AVIATION/12Z TAFS/... WILL BE A CHANCE FOR SHOWERS AND STORMS TODAY AS A COLD FRONT MOVES THROUGH THE FORECAST AREA. WILL PROBABLY SEE TWO ROUNDS...THE FIRST OF WHICH WILL ARRIVE IN THE NORTHWEST THIS MORNING. SOME UNCERTAINTY AS TO HOW WELL THIS WILL HOLD TOGETHER AS IT PROGRESSES SOUTHEAST. SECOND ROUND WILL LIKELY FIRE RIGHT AHEAD OF THE FRONT BY LATE AFTERNOON...WITH THE BEST CHANCE THEN ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA. SOME OF THE STORMS COULD BE STRONG TO SEVERE THIS AFTERNOON INTO EARLY EVENING. WILL THEN TURN DRY BY LATE EVENING...WITH QUIET WEATHER EXPECTED OVERNIGHT AND INTO SATURDAY. VFR CONDITIONS WILL PREVAIL THROUGH THE NEXT 24 HOURS...EXCEPT FOR LOWER VSBYS POSSIBLE IN ANY MODERATE TO HEAVY RAINFALL. MARINE... SOUTHWEST WINDS WILL LIKELY REACH SMALL CRAFT ADVISORY LEVELS TODAY AHEAD OF AN APPROACHING COLD FRONT. THE BEST CHANCE FOR HIGHER GUSTS WILL BE ALONG SHORE FROM MID MORNING INTO LATE AFTERNOON NORTH AND EARLY EVENING SOUTH. A SMALL CRAFT ADVISORY WILL THUS BE ISSUED THIS MORNING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR WIZ046-047-051-052- 056>060-062>072. LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LMZ643>646. && $$ UPDATE...ET/WOOD TODAY/TONIGHT AND AVIATION/MARINE...DDV SATURDAY THROUGH THURSDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
625 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT FRI JUL 19 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER RIDGING OVER THE WESTERN U.S. AS WELL AS OVER THE MID-ATLANTIC...WHILE TROUGHING WAS IN-BETWEEN FROM SOUTH CENTRAL CANADA INTO WESTERN MN. THIS TROUGHING IS COMPOSED OF A POTENT SHORTWAVE OVER MANITOBA...A SHORTWAVE FROM CENTRAL NORTH DAKOTA INTO NORTHERN MN...AND A DEEP DRY-SLOT AHEAD OF THE SHORTWAVE FROM SOUTH DAKOTA INTO WESTERN LAKE SUPERIOR. A COLD FRONT AT THE SURFACE WAS ANALYZED FROM NEAR SIOUX FALLS TO THUNDER BAY ONTARIO...SLIGHTLY AHEAD OF THE DRY SLOT. AMAZINGLY...DESPITE 4000 J/KG OF SBCAPE AND LITTLE CIN ON THE 00Z ABR SOUNDING...THE FRONT WENT THROUGH THERE WITH LITTLE ACTIVITY. BEST GUESS WAS THE LACK OF CONVERGENCE ON THE FRONT...WHICH WAS REPRESENTED WELL ON 0-2KM RAP CONVERGENCE PLOTS. FRONT IS MORE ACTIVE NOW...MORESO THE WARM ADVECTION AHEAD OF IT...WITH HIGHER BASED SHOWERS AND THUNDERSTORMS FROM FARMINGTON MN TO PARK FALLS WI. WARM AIR CONTINUES TO HOLD STRONG IN THE WARM SECTOR WITH READINGS IN THE UPPER 70S / LOW 80S...THANKS IN PART TO A 30-45 KT 925MB WINDS OVER THE AREA. THERE IS EVEN WARMER AIR FLOWING IN FROM THE WEST ALONG THE FRONT...OBSERVED ON THE 00Z ABR SOUNDING WITH AN 800MB TEMP OF 20C AND 925MB TEMP OF 30C...COMPARED TO 17C AND 27C RESPECTIVELY FROM THE 00Z MPX SOUNDING. BEHIND THE FRONT...925MB TEMPS ARE NOT THAT MUCH COOLER WITH 28C OBSERVED AT GGW...BUT DEWPOINTS DROP INTO THE 50S AND LOW 60S. SYNOPTIC OVERVIEW... UPPER TROUGHING IS STILL POISED TO FORM OVER THE WESTERN GREAT LAKES REGION BY 06Z TONIGHT...THOUGH THE MORE POTENT SHORTWAVE COMPOSING THE TROUGH IS FORECAST TO STAY UP IN CANADA. MEANWHILE...THE SHORTWAVE SEEN UP IN CENTRAL NORTH DAKOTA IS SLATED TO DROP INTO CENTRAL MN BY 18Z...THEN PUSH EAST INTO LOWER MI. WITH THE UPPER TROUGHING FORMING...EXPECT THE COLD FRONT TO CONTINUE MARCHING SOUTHEAST. MODEL TIMING IS WELL AGREED UPON...AT 18Z STRETCHING FROM OMAHA NEB TO VOLK FIELD WI AND MARINETTE WI...AND AT 00Z FROM NORTHWEST MO TO NEAR DUBUQUE IA AND UP TO MANITOWOC WI. HAZARDS... ONGOING HEAT ADVISORY...DUE TO FRONTAL TIMING AND DRYING DEWPOINTS BEHIND THE FRONT...HAVE CANCELLED SOME OF THE ADVISORY. AREAS INCLUDE SOUTHEAST MN AND PORTIONS OF NORTHEAST IOWA INTO CENTRAL WI. THERE ALSO IS A CHANCE FOR SEVERE WEATHER THIS AFTERNOON ALONG THE COLD FRONT COMING THROUGH NORTHEAST IOWA AND SOUTHWEST WI. 0-6KM SHEAR VALUES ARE HIGHER IN THE 09.00Z NAM...ORDER OF 30-40 KT VERSUS 20-30 KT IN THE 09.06Z RAP. IF SEVERE WEATHER OCCURS...DAMAGING WINDS WOULD BE THE MAIN HAZARDS. TODAY... TWO BIG QUESTIONS...TEMPERATURES AND PRECIPITATION CHANCES. ON THE PRECIPITATION SIDE OF THINGS...19.00Z GFS/NAM/REGIONAL CANADIAN ALL WANT TO BRING THE SHOWERS AND SOME THUNDERSTORMS THROUGH THE FORECAST AREA THIS MORNING PRIOR TO THE FRONTAL PASSAGE. THESE ORIGINATE FROM ISENTROPIC LIFT ON THE 310 K SURFACE AHEAD OF THE FRONT. IT APPEARS THESE SHOULD WEAKEN THROUGH THE MORNING TOO WITH THE NOCTURNAL LOW LEVEL JET WEAKENING. A PERIOD OF CLEARING THEN TAKES PLACE IN THE WARM SECTOR...WITH SOME HINTS FROM THE 19.00Z GFS/REGIONAL CANADIAN AND 19.06Z RAP THAT THE FRONT COULD CONVECT IN SOUTHEASTERN PORTION OF THE FORECAST AREA SAY BETWEEN 19-23Z. NOT THRILLED ABOUT THE FRONT CONVECTING AS THE 0-2KM CONVERGENCE IS VERY WEAK. HOWEVER...GIVEN MODELS HAVE BEEN SHOWING IT THE PAST FEW DAYS AND PLENTY OF INSTABILITY PROGGED TO DEVELOP TODAY...KEPT SOME CHANCES IN THE FORECAST. HAVE ALSO ADDED SOME LOW CHANCES OF PRECIPITATION FOR THE AFTERNOON HOURS FROM TAYLOR COUNTY SOUTH TO JACKSON. HERE ANOTHER FRONT LURKING UP IN NORTHERN MN IS PROGGED BY THE 09.06Z RAP AND 09.05Z HRRR TO COME THROUGH AND HAVE SOME CONVECTION ON IT. ON THE TEMPERATURE SIDE OF THINGS...A WARM START PLUS 925MB TEMPS HOLDING IN THE 24-26C RANGE SHOULD EASILY ALLOWS HIGHS TO REACH THE UPPER 80S TO POSSIBLY MID 90S AGAIN. THIS IS EVEN DESPITE THE FRONTAL PASSAGE GIVEN THE WARM AIR STILL HOLDING BACK AND LIKELY DEEPER MIXING BEHIND THE FRONT. HOWEVER...HEAT INDICES WILL FALL WITH THE FRONT AS DRIER DEWPOINTS FLOW IN. TONIGHT... SUBSIDENCE AND DRYING COMING IN BEHIND THE COLD FRONT WILL ALLOW FOR A MOSTLY CLEAR NIGHT ACROSS THE FORECAST AREA. DRIER AIR AND DIMINISHING WINDS SHOULD ALLOW TEMPERATURES TO FALL CLOSE TO GUIDANCE VALUES...IN THE UPPER 50S TO MID 60S...10-15 DEGREES COLDER THAN TONIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 321 AM CDT FRI JUL 19 2013 SYNOPTIC OVERVIEW... MUCH OF THE NEXT 6 DAYS LOOKS TO BE DOMINATED BY NORTHWEST FLOW ACCORDING TO THE 19.00Z ECMWF/GFS/CANADIAN WITH RIDGING STAYING PUT OVER THE WESTERN U.S.. THERE ARE SOME SIGNS FROM THE ECMWF THE RIDGE MAY WANT TO BUILD EAST TOWARDS THE FORECAST AREA ON THURSDAY...BUT PLENTY OF UNCERTAINTY ON THAT SEEING THE TROUGHING IN THE GFS. ADDITIONALLY...THIS NORTHWEST FLOW HAS UNCERTAINTY IN TERMS OF TIMING SHORTWAVES AND THE CHANCES OF PRECIPITATION WITH THEM. SATURDAY THROUGH SUNDAY NIGHT... MAIN FEATURE OF INTEREST DURING THIS PERIOD IS A SHORTWAVE ALL MODELS HAVE TRACKING OUT OF MONTANA ON SATURDAY AND THROUGH THE FORECAST AREA ON SUNDAY. SURPRISINGLY MODELS ARE IN REALLY GOOD AGREEMENT WITH THIS SHORTWAVE...ALBEIT PERHAPS THE GFS HAS A BIT OF CONVECTIVE FEEDBACK TO IT. IN ANY EVENT...INCREASING 310 K ISENTROPIC LIFT COMBINED WITH INSTABILITY SHOULD INITIATE CONVECTION OVER EASTERN SOUTH DAKOTA DURING THE AFTERNOON. THIS CONVECTION THEN SPREADS TOWARDS THE FORECAST AREA SATURDAY NIGHT AS THE ISENTROPIC LIFT AND 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE SHIFTS EAST. PERHAPS THERE IS A SHOT SOME HIGH BASED SHOWERS COULD DEVELOP DOWNSTREAM OF THE CONVECTION SATURDAY AFTERNOON...BUT THINK THE BULK OF THE PRECIPITATION WOULD WAIT UNTIL SATURDAY NIGHT. SUNDAY APPEARS TO HAVE THE HIGHEST CHANCE OF RAIN WHERE DPVA ACCOMPANYING THE SHORTWAVE INTERSECTS 850MB MOISTURE TRANSPORT CONTINUING TO AIM AT THE AREA. ITS HARD TO SAY HOW SUNDAY NIGHT WILL EVOLVE. SUBSIDENCE BEHIND THE SHORTWAVE MOVING THROUGH ON SUNDAY WOULD SEEM TO LIKELY PROVIDE A DRY PERIOD...LIKE SUGGESTED BY THE 19.00Z NAM. HOWEVER... THE 19.00Z GFS/ECMWF SHOW A POTENT SHORTWAVE TROUGH CROSSING SOUTHERN MANITOBA SUNDAY NIGHT...WHICH INCREASES 850MB MOISTURE TRANSPORT INTO THE AREA. THEREFORE...THESE MODELS WANT TO HANG ONTO SOME SHOWERS. HAVE MAINTAINED SOME CHANCES OF PRECIPITATION TO ACCOUNT FOR THE GFS/ECMWF SCENARIO. BIGGEST ISSUE IN THE TEMPERATURE DEPARTMENT IS HIGHS ON SUNDAY. IF IT RAINS ALL DAY...TEMPERATURES MAY GET STUCK IN THE UPPER 60S/LOW 70S. FOR NOW TRENDED HIGHS DOWN SLIGHTLY. MONDAY THROUGH THURSDAY NIGHT... THIS PERIOD IS HIGHLY UNCERTAIN. 19.00Z GFS/ECMWF/CANADIAN SHOW NUMEROUS SHORTWAVES MOVING THROUGH THE NORTHWEST FLOW ALOFT THROUGH MUCH OF THE WEEK. TIMING AND TRACK OF THESE VARIES FROM RUN TO RUN...THUS THE LOW CONFIDENCE. THERE DOES APPEAR TO BE SOME SIGNAL FOR A COLD FRONT COMING THROUGH THE FORECAST AREA MONDAY NIGHT...ASSOCIATED WITH THAT POTENT TROUGH OVER SOUTHERN MANITOBA PROGGED TO LIFT EAST-NORTHEAST. IF THIS STAYS CONSISENT...WE MIGHT BE ABLE TO DRY OUT TUESDAY. OTHERWISE...HAVE MAINTAINED A MODEL CONSENSUS OF 20-40 PERCENT CHANCES THROUGH THURSDAY NIGHT. LIKELY THE ENTIRE PERIOD WILL NOT BE WET...BUT HARD TO PIN POINT MUCH FOR POSSIBLE DRY PERIODS BEYOND TUESDAY. WITH A NORTHWEST FLOW IN PLACE...EXPECT A COOLER FLOW OF AIR. 850MB TEMPS ARE GENERALLY PROGGED TO DROP FROM 18-20C ON MONDAY TO 12-15C FOR TUESDAY THROUGH THURSDAY. THESE SHOULD RESULT IN A DROP IN HIGHS TO SLIGHTLY BELOW NORMAL AFTER NEAR NORMAL ON MONDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 625 AM CDT FRI JUL 19 2013 A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY BRINGING SCATTERED SHOWERS AND THUNDERSTORMS TO THE TAF SITES EARLY. THE FRONT IS EXPECTED TO PUSH SOUTH OF THE TAF SITES BY EARLY THIS AFTERNOON WITH WINDS SWITCHING TO THE NORTHWEST AND INCREASING TO 15 TO 18 KTS WITH GUSTS TO AROUND 25 KTS POSSIBLE. SOME OF THE STORMS MAY PRODUCE BRIEF HEAVY DOWNPOURS AND GUSTY WINDS TO 45 KTS THIS MORNING. WILL HAVE TO KEEP A VERY CLOSE WATCH FOR STORMS REDEVELOPING ALONG THE FRONT LATE THIS MORNING INTO THIS AFTERNOON. A FEW OF THESE STORMS COULD BECOME SEVERE WITH DAMAGING WINDS. HIGH PRESSURE WILL BUILD INTO THE REGION TONIGHT PROVIDING VFR CONDITIONS. SOME PATCHY FOG IS POSSIBLE TONIGHT...ESPECIALLY IN VALLEY LOCATIONS. && .CLIMATE... ISSUED AT 321 AM CDT FRI JUL 19 2013 LA CROSSE WI HAS ONLY SEEN 0.27 INCHES FOR THE MONTH OF JULY THROUGH THE 18TH. THIS IS THE 5TH DRIEST START TO JULY. THE DRIEST THROUGH JULY 18TH WAS 0.05 INCHES BACK IN 1896...AND THE LAST TIME IT WAS THIS DRY WAS IN 1967. FOR REFERENCE...LA CROSSE NORMALLY SHOULD HAVE 2.41 INCHES UP THROUGH THE 18TH. ROCHESTER MN HAS HAD QUITE A BIT MORE RAIN...THUS THE 1.42 INCHES OBSERVED THROUGH JULY 18TH IS WELL OUTSIDE THE TOP 20 DRIEST. STILL ROCHESTER IS 1.25 INCHES BELOW NORMAL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR WIZ041>044-053>055- 061. MN...NONE. IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ011-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...WETENKAMP CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 AM CDT FRI JUL 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT FRI JUL 19 2013 CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED UPPER RIDGING OVER THE WESTERN U.S. AS WELL AS OVER THE MID-ATLANTIC...WHILE TROUGHING WAS IN-BETWEEN FROM SOUTH CENTRAL CANADA INTO WESTERN MN. THIS TROUGHING IS COMPOSED OF A POTENT SHORTWAVE OVER MANITOBA...A SHORTWAVE FROM CENTRAL NORTH DAKOTA INTO NORTHERN MN...AND A DEEP DRY-SLOT AHEAD OF THE SHORTWAVE FROM SOUTH DAKOTA INTO WESTERN LAKE SUPERIOR. A COLD FRONT AT THE SURFACE WAS ANALYZED FROM NEAR SIOUX FALLS TO THUNDER BAY ONTARIO...SLIGHTLY AHEAD OF THE DRY SLOT. AMAZINGLY...DESPITE 4000 J/KG OF SBCAPE AND LITTLE CIN ON THE 00Z ABR SOUNDING...THE FRONT WENT THROUGH THERE WITH LITTLE ACTIVITY. BEST GUESS WAS THE LACK OF CONVERGENCE ON THE FRONT...WHICH WAS REPRESENTED WELL ON 0-2KM RAP CONVERGENCE PLOTS. FRONT IS MORE ACTIVE NOW...MORESO THE WARM ADVECTION AHEAD OF IT...WITH HIGHER BASED SHOWERS AND THUNDERSTORMS FROM FARMINGTON MN TO PARK FALLS WI. WARM AIR CONTINUES TO HOLD STRONG IN THE WARM SECTOR WITH READINGS IN THE UPPER 70S / LOW 80S...THANKS IN PART TO A 30-45 KT 925MB WINDS OVER THE AREA. THERE IS EVEN WARMER AIR FLOWING IN FROM THE WEST ALONG THE FRONT...OBSERVED ON THE 00Z ABR SOUNDING WITH AN 800MB TEMP OF 20C AND 925MB TEMP OF 30C...COMPARED TO 17C AND 27C RESPECTIVELY FROM THE 00Z MPX SOUNDING. BEHIND THE FRONT...925MB TEMPS ARE NOT THAT MUCH COOLER WITH 28C OBSERVED AT GGW...BUT DEWPOINTS DROP INTO THE 50S AND LOW 60S. SYNOPTIC OVERVIEW... UPPER TROUGHING IS STILL POISED TO FORM OVER THE WESTERN GREAT LAKES REGION BY 06Z TONIGHT...THOUGH THE MORE POTENT SHORTWAVE COMPOSING THE TROUGH IS FORECAST TO STAY UP IN CANADA. MEANWHILE...THE SHORTWAVE SEEN UP IN CENTRAL NORTH DAKOTA IS SLATED TO DROP INTO CENTRAL MN BY 18Z...THEN PUSH EAST INTO LOWER MI. WITH THE UPPER TROUGHING FORMING...EXPECT THE COLD FRONT TO CONTINUE MARCHING SOUTHEAST. MODEL TIMING IS WELL AGREED UPON...AT 18Z STRETCHING FROM OMAHA NEB TO VOLK FIELD WI AND MARINETTE WI...AND AT 00Z FROM NORTHWEST MO TO NEAR DUBUQUE IA AND UP TO MANITOWOC WI. HAZARDS... ONGOING HEAT ADVISORY...DUE TO FRONTAL TIMING AND DRYING DEWPOINTS BEHIND THE FRONT...HAVE CANCELLED SOME OF THE ADVISORY. AREAS INCLUDE SOUTHEAST MN AND PORTIONS OF NORTHEAST IOWA INTO CENTRAL WI. THERE ALSO IS A CHANCE FOR SEVERE WEATHER THIS AFTERNOON ALONG THE COLD FRONT COMING THROUGH NORTHEAST IOWA AND SOUTHWEST WI. 0-6KM SHEAR VALUES ARE HIGHER IN THE 09.00Z NAM...ORDER OF 30-40 KT VERSUS 20-30 KT IN THE 09.06Z RAP. IF SEVERE WEATHER OCCURS...DAMAGING WINDS WOULD BE THE MAIN HAZARDS. TODAY... TWO BIG QUESTIONS...TEMPERATURES AND PRECIPITATION CHANCES. ON THE PRECIPITATION SIDE OF THINGS...19.00Z GFS/NAM/REGIONAL CANADIAN ALL WANT TO BRING THE SHOWERS AND SOME THUNDERSTORMS THROUGH THE FORECAST AREA THIS MORNING PRIOR TO THE FRONTAL PASSAGE. THESE ORIGINATE FROM ISENTROPIC LIFT ON THE 310 K SURFACE AHEAD OF THE FRONT. IT APPEARS THESE SHOULD WEAKEN THROUGH THE MORNING TOO WITH THE NOCTURNAL LOW LEVEL JET WEAKENING. A PERIOD OF CLEARING THEN TAKES PLACE IN THE WARM SECTOR...WITH SOME HINTS FROM THE 19.00Z GFS/REGIONAL CANADIAN AND 19.06Z RAP THAT THE FRONT COULD CONVECT IN SOUTHEASTERN PORTION OF THE FORECAST AREA SAY BETWEEN 19-23Z. NOT THRILLED ABOUT THE FRONT CONVECTING AS THE 0-2KM CONVERGENCE IS VERY WEAK. HOWEVER...GIVEN MODELS HAVE BEEN SHOWING IT THE PAST FEW DAYS AND PLENTY OF INSTABILITY PROGGED TO DEVELOP TODAY...KEPT SOME CHANCES IN THE FORECAST. HAVE ALSO ADDED SOME LOW CHANCES OF PRECIPITATION FOR THE AFTERNOON HOURS FROM TAYLOR COUNTY SOUTH TO JACKSON. HERE ANOTHER FRONT LURKING UP IN NORTHERN MN IS PROGGED BY THE 09.06Z RAP AND 09.05Z HRRR TO COME THROUGH AND HAVE SOME CONVECTION ON IT. ON THE TEMPERATURE SIDE OF THINGS...A WARM START PLUS 925MB TEMPS HOLDING IN THE 24-26C RANGE SHOULD EASILY ALLOWS HIGHS TO REACH THE UPPER 80S TO POSSIBLY MID 90S AGAIN. THIS IS EVEN DESPITE THE FRONTAL PASSAGE GIVEN THE WARM AIR STILL HOLDING BACK AND LIKELY DEEPER MIXING BEHIND THE FRONT. HOWEVER...HEAT INDICES WILL FALL WITH THE FRONT AS DRIER DEWPOINTS FLOW IN. TONIGHT... SUBSIDENCE AND DRYING COMING IN BEHIND THE COLD FRONT WILL ALLOW FOR A MOSTLY CLEAR NIGHT ACROSS THE FORECAST AREA. DRIER AIR AND DIMINISHING WINDS SHOULD ALLOW TEMPERATURES TO FALL CLOSE TO GUIDANCE VALUES...IN THE UPPER 50S TO MID 60S...10-15 DEGREES COLDER THAN TONIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 321 AM CDT FRI JUL 19 2013 SYNOPTIC OVERVIEW... MUCH OF THE NEXT 6 DAYS LOOKS TO BE DOMINATED BY NORTHWEST FLOW ACCORDING TO THE 19.00Z ECMWF/GFS/CANADIAN WITH RIDGING STAYING PUT OVER THE WESTERN U.S.. THERE ARE SOME SIGNS FROM THE ECMWF THE RIDGE MAY WANT TO BUILD EAST TOWARDS THE FORECAST AREA ON THURSDAY...BUT PLENTY OF UNCERTAINTY ON THAT SEEING THE TROUGHING IN THE GFS. ADDITIONALLY...THIS NORTHWEST FLOW HAS UNCERTAINTY IN TERMS OF TIMING SHORTWAVES AND THE CHANCES OF PRECIPITATION WITH THEM. SATURDAY THROUGH SUNDAY NIGHT... MAIN FEATURE OF INTEREST DURING THIS PERIOD IS A SHORTWAVE ALL MODELS HAVE TRACKING OUT OF MONTANA ON SATURDAY AND THROUGH THE FORECAST AREA ON SUNDAY. SURPRISINGLY MODELS ARE IN REALLY GOOD AGREEMENT WITH THIS SHORTWAVE...ALBEIT PERHAPS THE GFS HAS A BIT OF CONVECTIVE FEEDBACK TO IT. IN ANY EVENT...INCREASING 310 K ISENTROPIC LIFT COMBINED WITH INSTABILITY SHOULD INITIATE CONVECTION OVER EASTERN SOUTH DAKOTA DURING THE AFTERNOON. THIS CONVECTION THEN SPREADS TOWARDS THE FORECAST AREA SATURDAY NIGHT AS THE ISENTROPIC LIFT AND 850MB MOISTURE TRANSPORT AHEAD OF THE SHORTWAVE SHIFTS EAST. PERHAPS THERE IS A SHOT SOME HIGH BASED SHOWERS COULD DEVELOP DOWNSTREAM OF THE CONVECTION SATURDAY AFTERNOON...BUT THINK THE BULK OF THE PRECIPITATION WOULD WAIT UNTIL SATURDAY NIGHT. SUNDAY APPEARS TO HAVE THE HIGHEST CHANCE OF RAIN WHERE DPVA ACCOMPANYING THE SHORTWAVE INTERSECTS 850MB MOISTURE TRANSPORT CONTINUING TO AIM AT THE AREA. ITS HARD TO SAY HOW SUNDAY NIGHT WILL EVOLVE. SUBSIDENCE BEHIND THE SHORTWAVE MOVING THROUGH ON SUNDAY WOULD SEEM TO LIKELY PROVIDE A DRY PERIOD...LIKE SUGGESTED BY THE 19.00Z NAM. HOWEVER... THE 19.00Z GFS/ECMWF SHOW A POTENT SHORTWAVE TROUGH CROSSING SOUTHERN MANITOBA SUNDAY NIGHT...WHICH INCREASES 850MB MOISTURE TRANSPORT INTO THE AREA. THEREFORE...THESE MODELS WANT TO HANG ONTO SOME SHOWERS. HAVE MAINTAINED SOME CHANCES OF PRECIPITATION TO ACCOUNT FOR THE GFS/ECMWF SCENARIO. BIGGEST ISSUE IN THE TEMPERATURE DEPARTMENT IS HIGHS ON SUNDAY. IF IT RAINS ALL DAY...TEMPERATURES MAY GET STUCK IN THE UPPER 60S/LOW 70S. FOR NOW TRENDED HIGHS DOWN SLIGHTLY. MONDAY THROUGH THURSDAY NIGHT... THIS PERIOD IS HIGHLY UNCERTAIN. 19.00Z GFS/ECMWF/CANADIAN SHOW NUMEROUS SHORTWAVES MOVING THROUGH THE NORTHWEST FLOW ALOFT THROUGH MUCH OF THE WEEK. TIMING AND TRACK OF THESE VARIES FROM RUN TO RUN...THUS THE LOW CONFIDENCE. THERE DOES APPEAR TO BE SOME SIGNAL FOR A COLD FRONT COMING THROUGH THE FORECAST AREA MONDAY NIGHT...ASSOCIATED WITH THAT POTENT TROUGH OVER SOUTHERN MANITOBA PROGGED TO LIFT EAST-NORTHEAST. IF THIS STAYS CONSISENT...WE MIGHT BE ABLE TO DRY OUT TUESDAY. OTHERWISE...HAVE MAINTAINED A MODEL CONSENSUS OF 20-40 PERCENT CHANCES THROUGH THURSDAY NIGHT. LIKELY THE ENTIRE PERIOD WILL NOT BE WET...BUT HARD TO PIN POINT MUCH FOR POSSIBLE DRY PERIODS BEYOND TUESDAY. WITH A NORTHWEST FLOW IN PLACE...EXPECT A COOLER FLOW OF AIR. 850MB TEMPS ARE GENERALLY PROGGED TO DROP FROM 18-20C ON MONDAY TO 12-15C FOR TUESDAY THROUGH THURSDAY. THESE SHOULD RESULT IN A DROP IN HIGHS TO SLIGHTLY BELOW NORMAL AFTER NEAR NORMAL ON MONDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1111 PM CDT THU JUL 18 2013 A COLD FRONT WILL SWEEP SOUTHEAST ACROSS THE REGION EARLY ON FRIDAY MORNING...LIKELY AROUND THE 15Z TIME FRAME FOR KRST/KLSE...GIVE OR TAKE AN HOUR. MOISTURE FIELDS AND BUFKIT SOUNDINGS SUGGEST MOSTLY MID LEVEL/VFR CLOUDS WITH THE FRONT AS IT MOVES THROUGH...SCATTERING OUT AS IT PASSES. SHOULD BE ENOUGH INSTABILTY AND LIFT IN THE VICINITY OF THE FRONT FOR SCATTERED SHRA/TS. WHETHER THEY WILL IMPACT KRST/KLSE IS STILL NOT CLEAR...SOME PCPN SHOULD BE IN THE AREA. WILL GO WITH A MIX OF -SHRA/VCSH FOR NOW...LEAVING OUT A MENTION OF TS AND ANY VSBY RESTRICTIONS FOR NOW. THIS WILL BE ADJUSTED AS NEEDED BASED ON RADAR/MESO MODEL TRENDS. FOR WINDS...SOUTH-SOUTHWEST WILL SWING TO THE NORTHWEST WITH THE PASSAGE OF THE FRONT. BUFKIT SOUNDINGS CONTINUE TO SUGGEST LLWS WILL BE A CONCERN...WITH NEAR 50 KTS OF WIND BY 2 KFT FOR A FEW HOURS AT KRST AND AROUND 45 KTS AT KLSE OVERNIGHT. WILL CONTINUE LLWS MENTION IN THE TAFS. && .CLIMATE... ISSUED AT 321 AM CDT FRI JUL 19 2013 LA CROSSE WI HAS ONLY SEEN 0.27 INCHES FOR THE MONTH OF JULY THROUGH THE 18TH. THIS IS THE 5TH DRIEST START TO JULY. THE DRIEST THROUGH JULY 18TH WAS 0.05 INCHES BACK IN 1896...AND THE LAST TIME IT WAS THIS DRY WAS IN 1967. FOR REFERENCE...LA CROSSE NORMALLY SHOULD HAVE 2.41 INCHES UP THROUGH THE 18TH. ROCHESTER MN HAS HAD QUITE A BIT MORE RAIN...THUS THE 1.42 INCHES OBSERVED THROUGH JULY 18TH IS WELL OUTSIDE THE TOP 20 DRIEST. STILL ROCHESTER IS 1.25 INCHES BELOW NORMAL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR WIZ041>044-053>055- 061. MN...NONE. IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ011-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
250 AM MST SUN JUL 21 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM IN MEXICO WILL CONTINUE TO SUPPLY MOISTURE TO THE DESERT SOUTHWEST TODAY. HUMID CONDITIONS WILL RESULT IN WELL-ABOVE NORMAL RAIN CHANCES AND WELL-BELOW NORMAL TEMPERATURES. A DRYING TREND WILL BEGIN MONDAY...CONTINUING INTO WEDNESDAY AS HIGH PRESSURE BUILDS BACK OVER THE REGION. MONSOON MOISTURE MOVING BACK NORTHWARD INTO THE REGION IS LIKELY TO ONCE AGAIN INCREASE RAIN CHANCES FOR THE END OF THE WEEK AND INTO THE WEEKEND. && .DISCUSSION... UPPER LOW CONTINUES TO SPIN WESTWARD INTO THE PACIFIC OCEAN JUST OFF THE BAJA PENINSULA. FURTHER NORTH...THE MID-TROPOSPHERIC ANTICYCLONE REMAINS POSITIONED ACROSS CA/NV. RESULTING MID-LEVEL EASTERLY FLOW IS STRONGER THAN NORMAL (STANDARDIZED ANOMALY NEAR 1.0) AND CONTINUES TO ADVECT DEEP SUB-TROPICAL MOISTURE INTO THE FORECAST AREA. SURFACE DEWPOINTS ARE CURRENTLY IN THE LOWER 70S ACROSS THE PHOENIX METRO AREA WHILE THE GPS-IPW REGISTERED AROUND 1.75 INCHES...WELL ABOVE NORMAL. LATEST RAP INDICATES THAT PWATS MAY BE AS HIGH AS 2.0 TO 2.4 INCHES ACROSS THE SOUTHWEST DESERTS AND TOWARDS PUERTO PENASCO. LATEST WV IMAGERY SHOWS TWO MCSS...ONE ACROSS THE MOJAVE DESERT AND THE OTHER ACROSS SOUTHERN AZ...BEARING DOWN ON SW AZ AND SE CA. STRONG LOW-LEVEL CONVERGENCE IS EXPECTED EARLY THIS MORNING AND POPS WERE INCREASED IN THESE AREAS. ACROSS SOUTH-CENTRAL AZ...NMM AND WRF-BASED GUIDANCE CONTINUES TO SUGGEST THAT SHOWERS WILL REDEVELOP AS EARLY AS THIS MORNING. THIS SEEMS REASONABLE GIVEN THE AMPLE MOISTURE AND IT WILL ONLY TAKE A MINIMAL AMOUNT OF HEATING FOR CONVECTION TO INITIATE. MODELS ALSO SUGGEST THAT VORTICITY-FORCED ASCENT WILL AID IN THE DEVELOPMENT OF STORMS THIS AFTERNOON ACROSS SE CA. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN AND LOCALIZED FLOODING. THE COPIOUS AMOUNT OF MOISTURE WILL ALSO RESULT IN CONSIDERABLE CLOUDINESS ACROSS MUCH OF THE AREA...WHICH WILL KEEP TEMPERATURES WELL BELOW NORMAL. FORECAST HIGH FOR PHOENIX IS 95 DEGREES. A MAX TEMP THIS LOW HAS NOT OCCURRED SINCE MAY 27. A SIGNIFICANT DRYING TREND WILL TAKE PLACE MONDAY AS THE UPPER LOW LIFTS STEADILY NORTHWARD. SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...THOUGH COVERAGE WILL BE NOTICEABLY LESS THAN WHAT HAS OCCURRED THE PAST FEW DAYS. THE UPPER LOW WILL BE PICKED UP BY THE WESTERLIES TUESDAY AS THE MONSOON HIGH BECOMES REPOSITIONED ACROSS THE ROCKIES. GFS/ECMWF DIFFER ON THE AMOUNT OF MOISTURE LEFT OVER ACROSS THE DESERT SOUTHWEST THOUGH THE CONSENSUS IS THAT IT SHOULD BE SUFFICIENT FOR ISOLATED THUNDERSTORMS THROUGH THE WEEK. FLOW WILL BE WEAK AS AN ANTICYCLONE BUILDS BACK ACROSS AZ AND CONVECTION WILL MAINLY BE RELEGATED TO THE HIGHER TERRAIN. A WARMING TREND IS ALSO EXPECTED WITH A RETURN TO ABOVE NORMAL TEMPERATURES BY THURSDAY. MODELS ARE IN GENERALLY GOOD AGREEMENT THAT ANOTHER PVD WILL SLIDE WESTWARD THROUGH SONORA LATE IN THE WEEK...RESULTING IN AN INFLUX OF MOISTURE. FORECAST IS FOR BELOW CLIMO POPS THROUGH MIDWEEK...FOLLOWED BY NEAR CLIMO POPS THURSDAY THROUGH SUNDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... VERY LOW CONFIDENCE AVIATION FORECAST FOR CNTRL ARIZONA THROUGH SUNDAY AFTERNOON WITH THUNDERSTORM COVERAGE AND MOVEMENT COMPLETELY DICTATING IMPACT TIMING AND DURATION. WHILE MOST TSTMS SHOULD CONGEAL WEST OF THE TERMINALS...SCT ACTIVITY MOVING WEST FROM HIGHER TERRAIN TO THE EAST COULD ARRIVE BETWEEN 02Z-06Z. CONCURRENTLY...NUMEROUS OUTFLOW BOUNDARIES FROM CONVECTION SURROUNDING THE AREA MAY CAUSE FREQUENTLY SHIFTING SFC WINDS ORIENTED FROM MANY DIFFERENT DIRECTIONS. ATTEMPTED TO CAPTURE GENERAL TRENDS IN THIS TAF PACKAGE...WITH THE EXPECTATION OF SEVERAL AMENDMENTS BASED ON SHORT TERM TRENDS. SEVERAL MODELS SUGGEST EXTENSIVE CLOUD COVER AND SHOWERS LINGERING ACROSS CNTRL ARIZONA SUNDAY MORNING. HAVE ADDED A VCSH MENTION WITH LOWERING CIGS...THOUGH KEPT HEIGHTS ABOVE 6K FT. THERE ARE INDICATIONS CIGS COULD FALL BLO 6K FT FOR A PERIOD NECESSITATING REDUCED ACCEPTANCE RATES...THOUGH CONFIDENCE WAS TOO LOW TO INCLUDE AT THIS TIME. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... SCATTERED SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO APPROACH SERN CALIFORNIA TERMINALS LATER THIS EVENING AND OVERNIGHT. OVERALL FORECAST CONFIDENCE IS RATHER LOW REGARDING THE COVERAGE AND TIMING OF TSTMS AND AVIATION IMPACTS. HAVE ATTEMPTED TO INDICATE A TRENDS OF SHIFTING WINDS AND VCTS/VCSH INTO TERMINAL TOWARDS THE LATE EVENING AND OVERNIGHT HOURS. SHOWERS COULD LINGER INTO SUNDAY MORNING...BUT DID NOT INCLUDE ANY MENTION IN THIS TAF PACKAGE GIVEN EXTREMELY LOW CONFIDENCE. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... A SWITCH TO A SOUTHERLY FLOW ALOFT WILL BRING DRYING CONDITIONS AND ENDING PRECIPITATION CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. SLIGHT CHANCES FOR STORMS WILL CONTINUE ACROSS SOUTH-CENTRAL ARIZONA WITH BETTER CHANCES ACROSS HIGHER TERRAIN LOCATIONS NORTH AND EAST OF PHOENIX. HUMIDITIES WILL REMAIN ELEVATED THROUGH THE ENTIRE PERIOD WITH AFTERNOON HUMIDITIES ONLY DROPPING INTO THE 20-30 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH AVIATION...MO FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1026 PM MDT SAT JUL 20 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 230 PM MDT SAT JUL 20 2013 THE HIGHER LEVEL MSTR PLUME HAS SHIFTED SOUTH OF THE AREA TODAY...BUT LOW LEVEL MSTR REMAINS IN PLACE WITH DEW POINTS MOSTLY IN THE 50S OVR THE SERN PLAINS AND AROUND 50 IN THE SAN LUIS VALLEY. EXPECTING MOST OF THE CONVECTIVE ACTIVITY THIS EVENING TO BE OVR AND NR THE MTS. SO FAR TODAY...THE SHOWERS THAT HAVE DEVELOPED WERE MOVING AROUND 10-12 MPH TO THE SE OR SSE. THIS SLOW MOVEMENT WL AGAIN LEAD TO THE CONCERN FOR LOCALLY HEAVY RAIN ON THE BURN SCARS AND THE POTENTIAL FOR FLASH FLOODING IF A HEAVIER STORM MOVES OVR OR DEVELOPS ON A BURN SCAR. THE NAM AND HRRR MOVE SOME STORMS OFF THE MTS AND ACRS THE I-25 CORRIDOR...MAINLY OVR EL PASO AND NRN PUEBLO COUNTIES THIS EVENING. A SHORTWAVE TROF MOVING ACRS NERN AND EAST CENTRAL CO TONIGHT IS EXPECTED TO BRING SOME CONVECTIVE ACTIVITY TO THOSE AREAS...BUT AT THIS TIME THE HI RES MODELS ARE KEEPING THAT MAINLY NORTH OF THE CWA...BUT COULD SEE SOME SHOWERS/TSTMS IN KIOWA COUNTY ASSOC WITH THE DISTURBANCE. WE COULD SEE A FEW LINGERING SHOWERS OVR THE MTS UNTIL MIDNIGHT OR A LITTLE LATER...BUT THEN BY MORNING ALL AREAS SHOULD BE DRY. ON SUN IT LOOKS LIKE SOME ISOLD TO SCT SHOWER/TSTMS COULD DEVELOP OVR THE HYR TRRN AROUND NOON...WITH THE BEST CHANCES BEING OVR THE SW MTS AND THE SRN SANGRES. A WEAK DISTURBANCE IS EXPECTED TO MOVE ACRS NERN CO IN THE AFTERNOON...AND THE NAM HAS SOME CONVECTIVE ACTIVITY FIRING UP IN NORTHEAST AND EAST CENTRAL CO...INCLUDING KIOWA AND CROWLEY COUNTIES BY EVENING. THE GFS KEEPS THE CONVECTION OVR NERN CO. FOR NOW WL GO WITH A DRY FORECAST FOR THE FAR SERN PLAINS SUN AFTERNOON. HIGH TEMPS ON SUN LOOK A COUPLE OR FEW DEGREES WARMER THAN TODAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 230 PM MDT SAT JUL 20 2013 HOT AND MAINLY DRY CONDITIONS EXPECTED MON AND TUESDAY AS UPPER RIDGE RE-AMPLIFIES OVER THE WESTERN US. MOISTURE PLUME WILL REMAIN SUPPRESSED TO THE SOUTH BOTH DAYS...THOUGH PERHAPS JUST ENOUGH RESIDUAL LOW LEVEL MOISTURE WILL LINGER TO PRODUCE AN ISOLATED HIGH BASED TSRA OVER THE MOUNTAINS...ESPECIALLY MON. WITH HEIGHTS RISING AND 700 MB TEMPS CLIMBING TOWARD 20C...EXPECT MAX TEMPS MON/TUE WILL REACH 100F PLUS OVER THE LOWER ARKANSAS VALLEY...WITH 80S/90S ELSEWHERE. FRONT DROPS THROUGH THE EASTERN PLAINS LATE TUE NIGHT/EARLY WED...LEADING TO A RENEWED WESTWARD PUSH OF MOISTURE BY WED AFTERNOON. ECMWF HAS TRENDED TOWARD THE GFS ON WED...AND BOTH MODELS NOW SUGGEST INCREASED CHANCES FOR TSRA OVER THE EASTERN MOUNTAINS AND PLAINS WED AFTERNOON/EVENING. WESTERN MOUNTAINS AND VALLEYS SHOULD ALSO SEE AN UPSWING IN TSRA WED...AS WEAK PUSH OF MID LEVEL MOISTURE WORKS NORTHWARD UNDERNEATH THE UPPER RIDGE AXIS. FOR LATE WEEK INTO THE WEEKEND...STILL APPEARS AN INCREASE IN CONVECTION IS POSSIBLE MANY AREAS THU-SAT...THOUGH DIFFERENCES BETWEEN THE EUROPEAN AND GFS ARISE BEGINNING THU...AS EURO BRINGS A STRONG TROUGH THROUGH THE AREA...WHILE GFS IS WEAKER/SLOWER. GFS IS THUS RATHER DRY THU...THEN MOISTENS THE AREA FRI/SAT...WHILE FASTER ECMWF IS WETTER THU/FRI BEFORE DRYING SLIGHTLY ON SAT. HAVE FOLLOWED THE MORE CONSISTENT GFS AT THIS POINT...BUT MAIN MESSAGE OF BOTH MODELS IS A RETURN OF FAIRLY WIDESPREAD CONVECTION BY WEEK`S END. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1023 PM MDT SAT JUL 20 2013 A LIGHT -TSRA WILL BE POSSIBLE AT KPUB THROUGH 07 UTC TONIGHT. THE OTHER TWO TAF SITES WILL SEE NO SIGNIFICANT WEATHER. FOR TOMORROW...VFR CONDITIONS IS EXPECTED. ISOLD -TSRA COULD OCCUR BUT THE PROBABILITY OF IT OCCURRING IS TOO LOW TO MENTION EXPLICITLY IN THE TAF. IF TSRA DO OCCUR...THEY WILL BE CAPABLE OF LOCALLY GUSTY DOWNBURST WINDS. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...PETERSEN AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
352 AM EDT Sun Jul 21 2013 .NEAR TERM [Today and Tonight]... Rain coverage has diminished greatly between 04 and 06 UTC, with much of the forecast area dry at the time this discussion was composed (shortly after 06 UTC). GOES and RAP analyzed PWATs are still around or just above 2" across much of our area, so we remain in the midst of a plume of deep tropical moisture. Therefore, it is unsurprising that the majority of model guidance indicates an early start to showers today. Indications are that coverage may be higher today to the north of an Apalachicola to Valdosta line, where surface dewpoints and boundary layer mixing ratios (as analyzed by the RAP) appear to be slightly higher. We expect low-topped convective showers to increase in coverage in the western Florida Panhandle 11-14 UTC and then gradually overspread the rest of the area by 18/19 UTC. It appears to be more likely than not that most people will see measurable rainfall, but the showers today should be of a more scattered variety, and thus should not last very long at individual locations. Still, when showers do occur, we should continue to see heavy rain rates. PoPs were maintained ~60% over much of the area. High temperatures may be slightly warmer today with more breaks of sun - in the upper 80s in most locations. && .SHORT TERM [Monday Through Tuesday]... One item that keeps coming to mind if we are unable to shake this wet and troughy pattern across the SE US (for the second consecutive summer nonetheless), is that Tallahassee may soon become known as the Seattle of the South, only with much more rainfall and higher temps. Not really much else of value to add, other than that PoPs will continue above climo and Max temps will continue below, and the disturbed pattern and strong 1000-700mb Mean Layer Vector Winds will make the Sea Breeze very difficult to develop. && .LONG TERM [Tuesday Night through Friday]... The GFS and ECMWF continue to agree that a broad long wave trough will be the dominant large scale weather feature over the Southeast. During this time there will likely be multiple minor short waves rotating through the base of the trough, enhancing our rain chances at times as both models forecast plenty of deep layer moisture and CAPE. While the MOS PoP consensus is above climatology, we will forecast a fairly diurnal cycle, with the greatest PoP during the afternoon & evening hours (even though sometimes MCS`s can affect our area overnight in this type of pattern). Despite the above-climo PoPs, the MOS consensus high temperatures are in the lower to mid 90s, which is near climo. It`s interesting to note that the 1000-700mb lapse rates are forecast to be steeper than normal (6-7 C/km) through much of this period, with the GFS being the most unstable. While the mid tropospheric winds are not expected to be very strong, the thermodynamics may be more supportive of pulse severe storms than what we have seen in recent days. && .AVIATION [through 12 UTC Sunday]... IFR or LIFR CIGS are expected at all of the terminals (ABY, DHN, VLD, and TLH) except for ECP early this morning. Short term ensemble guidance is in good agreement on that scenario. There may also be some light fog, but most of the flight category reductions should be due to low ceilings. The low CIGS should scatter out or lift to VFR levels within a couple hours of sunrise. Expecting scattered +SHRA today with a few TS. It should be an early start with morning rain possible at ECP, DHN, and TLH, spreading to ABY and VLD in the afternoon hours (with lingering SHRA possible at the other terminals after 18z as well). && .MARINE... Light to moderate west to southwesterly winds and corresponding seas are expected to continue through much of the period, as the Synoptic scale pressure pattern remains a bit above normal from the usual summer doldrums. && .FIRE WEATHER... Red flag conditions are not expected for the next several days. && .HYDROLOGY... Due to the recent heavy rainfall across the eastern Florida Big Bend, area rivers are on the rise, and minor flooding could be possible along parts of the Aucilla and Econfina rivers during the next couple of days, although widespread additional heavy rainfall is not expected at this time. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 89 73 89 73 90 / 60 20 60 40 60 Panama City 87 75 87 76 87 / 60 20 60 40 50 Dothan 88 72 89 72 91 / 60 30 70 40 60 Albany 89 73 89 73 91 / 60 30 60 40 60 Valdosta 89 72 90 73 90 / 60 20 60 40 60 Cross City 88 73 90 73 89 / 50 20 50 30 50 Apalachicola 86 75 87 76 86 / 50 20 50 30 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Lamers SHORT TERM...Gould LONG TERM...Fournier AVIATION...Lamers MARINE...Gould FIRE WEATHER...Lamers HYDROLOGY...Lamers/Gould
AREA FORECAST DISCUSSION
NWS MIAMI FL
137 AM EDT SUN JUL 21 2013 .AVIATION... A CONVERGENT LINE OF SHOWERS AND STORMS REMAINED TO THE EAST OF KPBI EARLY THIS MORNING. SOME OF THESE SHOWERS MAY GET NEAR KPBI OVERNIGHT...SO ADDED VCSH. OTHERWISE...HIGH PRESSURE WILL CONTINUE TO BUILD INTO SOUTH FLORIDA THROUGH THE TAF PERIOD WITH DRIER CONDITIONS. LIGHT WINDS ARE EXPECTED THROUGH THE OVERNIGHT HOURS AND AGAIN TONIGHT. SEA BREEZE BOUNDARIES ARE FORECAST TO PUSH INLAND AT BOTH COASTS THIS AFTERNOON. SHOWER AND THUNDERSTORM ACTIVITY IS FORECAST TO REMAIN MAINLY ACROSS THE INTERIOR...BUT SHOWERS OR STORMS COULD GET NEAR KPBI AND KAPF IN THE AFTERNOON. && .PREV DISCUSSION... /ISSUED 1027 PM EDT SAT JUL 20 2013/ UPDATE... ONLY A FEW CHANGES WERE NECESSARY THIS EVENING BASED ON THE LATEST TRENDS AND OBSERVATIONS AROUND THE LOCAL AREA. OTHERWISE...THE PREVIOUS FORECAST PACKAGE REMAINS ON TRACK. THE AFTERNOON/EARLY EVENING CONVECTION THAT MOSTLY IMPACTED THE INTERIOR AREAS AROUND THE LAKE REGION HAS DIMINISHED. THE LATEST HRRR RUN HAS LINED UP WELL WITH THE CURRENT CONDITIONS AND GENERALLY INDICATES A QUIET NIGHT WITH THE EXCEPTION OF SOME SHOWERS DEVELOPING OVER THE ATLANTIC WATERS THROUGH THE OVERNIGHT HOURS. FOR SUNDAY...DRIER AIR WILL BEGIN TO SPREAD NORTH INTO THE AREA AS THE RIDGE BEGINS TO BUILD OVERHEAD AND THE WEAK TROUGH LIFTS AWAY FROM THE AREA. HOWEVER...LINGERING MOISTURE OVER THE NORTHERN HALF OF THE CWA...OR AROUND THE LAKE REGION...WITH PWAT VALUES AROUND 2" COMBINED WITH SW LOW-LEVEL FLOW WILL BE ENOUGH TO THE KEEP THE AFTERNOON/EVENING SHOWERS/TSTMS IN THE FORECAST. PREV DISCUSSION... /ISSUED 723 PM EDT SAT JUL 20 2013/ AVIATION... OUTFLOW FROM INTERIOR CONVECTION IS MEETING DECAYING SEA BREEZE BOUNDARY OVER THE EASTERN METROPOLITAN AREAS THIS EVENING...THUS VCSH/VCTS IN TAFS BROWARD AND PALM BEACH COUNTIES TERMINALS. OUTFLOW BOUNDARY SHOULD BRING A BRIEF PERIOD OF WNW WINDS TO MIAMI-DADE TERMINALS...SO HAVE INCLUDED A TEMPO GROUP NOTING THE WIND SHIFT. OTHERWISE...LIGHT ESE WINDS WILL PREVAIL...AT SPEEDS OF AROUND 5 KTS TONIGHT AND 10 KTS ON SUNDAY. HAVE REMOVED VCSH BEYOND MIDNIGHT...AS POPS OVER THE TERMINALS ARE BELOW 30 PERCENT THROUGH SUNDAY. PREV DISCUSSION... /ISSUED 213 PM EDT SAT JUL 20 2013/ SHORT TERM (TONIGHT-MONDAY NIGHT)... A STRONG MID LEVEL RIDGE OVER THE MID ATLANTIC STRETCHES WEST TO ACROSS CENTRAL/SOUTH FLORIDA WITH MID LATITUDE TROUGHS MOVING ACROSS THE NORTHERN TIER OF STATES AND CANADA. A TROPICAL WAVE IS CURRENTLY MOVING THROUGH THE WESTERN CARIBBEAN SOUTHWEST OF JAMAICA AND THE NORTHERN EXTENT OF THIS WAVE IS LOCATED FROM THE EASTERN FLORIDA STRAITS AND INTO THE BAHAMAS. THIS HAS INCREASED CONVECTIVE ACTIVITY IN THAT REGION WITH HIGHER PWAT VALUES MOVING INTO SOUTH FLORIDA WHICH IN TURN IS HELPING TO ENHANCE CONVECTION. THE 12Z MFL SOUNDING WAS QUITE IMPRESSIVE AS REGARDS TO THE AVAILABLE CAPE BUT SO FAR THE STORMS HAVE BEEN SOMEWHAT SUPPRESSED DUE TO THE WEAK MID LEVEL LAPSE RATES ASSOCIATED WITH THE RIDGE AXIS. THE LOW LEVELS WERE VERY UNSTABLE HOWEVER AND THIS AIDED IN AN EARLY START TO THE CONVECTION PROCESS WITH STORM MOTION TO THE NORTHWEST DUE TO THE LOW LEVEL SOUTHEAST FLOW. THE FLOW BECOMES VERY WEAK TO LIGHT SOUTHWEST IN THE MID LEVELS IN RESPONSE TO THE RIDGE SO AS THE STORMS CONTINUE TO GROW, THE INTERIOR COULD GET QUITE ACTIVE LATER THIS AFTERNOON AS THE STORM MOTION BECOMES LESS THAN 5 MPH. THE WAVE WILL CONTINUE TO MOVE WEST OF THE AREA ON SUNDAY BUT AS MOISTURE CONTINUES TO LINGER ACROSS THE REGION WITH A WEAK SURFACE TROUGH BOUNDARY REMAINING IN PLACE, SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED AGAIN BY LATE SUNDAY MORNING INTO THE AFTERNOON. DUE TO THE WAVE BEING FARTHER TO THE WEST, THE LOW LEVEL SOUTHEAST FLOW WILL BECOME SHALLOWER SO STORM MOTION WILL GO EVEN LIGHTER AND SEA BREEZE BOUNDARIES WILL LIKELY BE THE DOMINANT FOCUSING MECHANISM. AT THE SAME TIME, A SURFACE RIDGE WILL BUILD BACK ACROSS SOUTH FLORIDA BY SUNDAY AFTERNOON THROUGH MONDAY AND THIS COULD SUPPRESS CONVECTIVE ACTIVITY EVEN FURTHER WITH SEA BREEZE BOUNDARIES AGAIN BEING THE MAIN FOCUS FOR MONDAY AFTERNOON. LONG TERM (TUESDAY-SATURDAY)... THIS SAME TREND WILL LIKELY CONTINUE THROUGH THE MIDDLE OF THE WEEK AS A DEEP LAYER RIDGE BECOMES FIRMLY ESTABLISHED AND FORECAST SOUNDINGS SHOW STORM MOTION 2 MPH OR LESS. A STRONG MID LEVEL TROUGH WILL BEGIN TO DEEPEN INTO THE EASTERN STATES BY THURSDAY INTO THE END OF THE WEEK AND INTO THE FIRST PART OF NEXT WEEKEND FOR A SLOW RETURN TO STORM MOTION STEERING STORMS BACK TOWARDS THE EAST COAST. FORECAST SOUNDINGS HOWEVER ARE NOT SHOWING A STRONG MOTION SO THE ENTIRE WEEK LOOKS AS IF VERY SLOW STORM MOTION WILL CONTINUE A THREAT FOR LOCALLY HEAVY RAINS WHERE EVER THE CONVECTION CAN SET UP. MARINE... GENERAL EAST TO SOUTHEAST WIND IS EXPECTED THROUGH TUESDAY AT SPEEDS OF LESS THAN 15 KNOTS OUTSIDE OF SCATTERED SHOWERS/THUNDERSTORMS. THE WIND WILL BEGIN TO VEER TO A SOUTH OR SOUTHWEST DIRECTION LATER IN THE WEEK AS THE SURFACE RIDGE SHIFTS TO THE SOUTH. FIRE WEATHER... NO PROBLEMS WITH PLENTY OF TROPICAL MOISTURE IN PLACE. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 89 76 88 77 / 20 20 30 10 FORT LAUDERDALE 89 79 89 79 / 20 20 30 10 MIAMI 90 77 88 79 / 20 20 20 10 NAPLES 91 75 89 75 / 20 10 20 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...71/JE AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1150 PM CDT SAT JUL 20 2013 .DISCUSSION... ISSUED 858 PM CDT SAT JUL 20 2013 SOMEWHAT COMPLICATED SCENARIO FOR THE OVERNIGHT AS OPPOSED TO THE LAST SEVERAL NIGHTS. CONVECTION ALONG THE I-64 CORRIDOR HAS BEEN PERSISTENT THE LAST FEW HOURS. ALTHOUGH THE HEAVIEST RAIN IS NOW WELL SOUTH OF OUR AREA...THE EXTREME SOUTHEAST CWA HAS SEEN LIGHT TO MODERATE RAIN CONTINUING. THE FRONTAL BOUNDARY HAS BEGUN TO RETROGRADE WESTWARD...WITH IT APPEARING FAIRLY NICELY ON RADAR IMAGERY FROM JERSEYVILLE TO DECATUR TO JUST WEST OF CHAMPAIGN. LATEST RAP AND HRRR GUIDANCE DOES NOT SHOW MUCH IN THE WAY OF STEERING CURRENTS WHICH WOULD FULLY PUSH IT BACK SOUTHEAST OF THE AREA...BUT THEY INDICATE THAT IT SHOULD NOT GET TOO MUCH FURTHER NORTHWEST. WITH LIGHT WINDS...POOLING DEW POINTS NEAR 70 AND THE MOISTURE FROM THE HEAVIER RAIN POCKETS FROM EARLIER TODAY... HAVE SOME CONCERNS WITH FOG DEVELOPMENT ACROSS THE SOUTHEAST THIRD OF THE CWA DESPITE THE AMOUNT OF CLOUDS. HAVE ADDED SOME PATCHY FOG FOR THIS AREA OVERNIGHT. DID NOT REALLY CHANGE THE LOW TEMPERATURES...BUT HAD TO MAKE SOME SIGNIFICANT ADJUSTMENTS TO THE HOURLY TRENDS...ESPECIALLY IN THE SOUTHEAST DUE TO THE RAIN. UPDATED GRIDS HAVE BEEN SENT. EARLIER ZONE ISSUANCE AT 7 PM ALREADY TOOK INTO ACCOUNT MOST OF THE UPDATES...BUT WILL FRESHEN THIS AS WELL TO ADD THE FOG MENTION. GEELHART && .AVIATION... ISSUED 1150 PM CDT SAT JUL 20 2013 MAIN CONCERN IS WITH FOG POTENTIAL OVERNIGHT...MAINLY IN EASTERN ILLINOIS. HAVE ALREADY BEEN SEEING SOME CEILINGS BELOW 500 FEET AT TIMES IN AREAS SOUTH AND SOUTHEAST OF KCMI. THIS IS EAST OF THE FRONTAL BOUNDARY...WHERE TEMPERATURE/DEW POINT SPREADS ARE MINIMAL...AND IN LOCATIONS THAT SAW POCKETS OF 1 TO 3 INCHES OF RAIN ON SATURDAY. LATEST GUIDANCE FROM THE RAP/HRRR/LAMP MODELS SHOWING AN EXPANDING AREA OF FOG OVER THE NEXT FEW HOURS IN EAST CENTRAL ILLINOIS. HAVE HIT KCMI THE HARDEST WITH LIFR CONDITIONS DEVELOPING BY AROUND 08Z AND PERSISTING INTO EARLY MORNING. KDEC ALSO SHOWING SOME IFR POTENTIAL AND INCLUDED TEMPO PERIODS THERE AS WELL. FORECAST SOUNDINGS AT KPIA/KBMI/KSPI ARE DRIER...AND HAVE ONLY MENTIONED SOME 4SM VISIBILITIES AT TIMES. LATER ON...CONVECTION CONCERNS PREVAIL FROM ABOUT 21Z ONWARD. LATEST MODEL GUIDANCE IS EASING OFF SOME ON COVERAGE AND TIMING IN MUCH OF CENTRAL ILLINOIS...WITH MORE OF A FOCUS JUST SOUTH OF THE TAF SITES. HAVE MAINTAINED SOME VCTS MENTION AT KPIA/KSPI...BUT LEFT OUT THUNDER MENTION ELSEWHERE FOR NOW DUE TO THE UNCERTAINTY. GEELHART && .PREV DISCUSSION... ISSUED 248 PM CDT SAT JUL 20 2013 MODELS LOOK IN VERY GOOD AGREEMENT IN THE SHORT TERM PERIOD...AS MAIN CONCERN IS PCPN CHANCES AND TEMPS. EXTENDED MODELS HAVE SOME DIFFERENCES BUT THEY ARE MINOR AND DO NOT CHANGE THE OVERALL FORECAST THAT MUCH...EXCEPT TO BRING IN SOME DRIER PERIODS DURING MIDDLE OF THE WEEK. SO OVERALL CONFIDENCE IN FORECAST IS GOOD. SHORT TERM...TONIGHT THROUGH TUESDAY FRONT HAS BEEN MOVING SOUTH THROUGH THE AREA TODAY AND WILL CONTINUE TO MOVE SOUTH LATE THIS AFTERNOON AND EVENING. THUNDERSTORMS HAVE DEVELOPED ALONG THE FRONT AS IT HAS INTERACTED WITH JUICY AIR WITH LOWER TO MIDDLE 70S DEWPOINTS. WITH THUNDERSTORMS THAT HAVE NOW DEVELOPED JUST NORTH OF I-70...WILL HAVE A LATE AFTERNOON PERIOD IN THE WORDED FORECAST ONCE IT IS ISSUED. OTHERWISE...TONIGHT THUNDERSTORMS WILL JUST BE IN THE SOUTHEAST JUST FOR THIS EVENING AND THEN DRY FOR AFTER MIDNIGHT. AS CAN BE SEEN ON VISIBLE SATELLITE AND RADAR IMAGES OUT WEST...THE FRONT EXTENDS BACK TO THE NORTHWEST WITH MORE SHOWERS AND THUNDERSTORMS. THIS FRONT WILL BE THE FOCUS FOR MORE DEVELOPMENT TOMORROW THAT WILL ADVECT TOWARD WESTERN ILLINOIS TOMORROW MORNING AND CENTRAL ILLINOIS TOMORROW AFTERNOON. THUNDERSTORM CHANCES WILL CONTINUE INTO TOMORROW NIGHT AS A SHORT WAVE MOVES ACROSS THE AREA AS WELL. POPS WILL BE HIGHEST TOMORROW NIGHT DUE TO THIS SHORT WAVE AS WELL. PCPN CHANCES WILL CONTINUE INTO MONDAY...THOUGH LOWER...AS THE SHORT WAVE MOVES EAST OF THE AREA. A SECOND WAVE OR MCS WILL THEN DEVELOP OUT WEST AND MOVE INTO THE AREA FOR MON NIGHT INTO TUESDAY. THIS WILL BRING CONTINUED THUNDERSTORM CHANCES FROM WEST TO EAST. CHANCES THEN DIMINISH FROM THE WEST TUE INTO TUE NIGHT. TEMP WILL REMAIN WARM AND WITH HIGH DEWPOINTS...MUGGY CONDITIONS WILL CONTINUE. AFTERNOON HIGHS ARE EXPECTED TO STILL REACH INTO THE MIDDLE TO UPPER 80S WITH NEAR 90 DEGREES IN THE SOUTHEAST ON MONDAY. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY AS THE SECOND WAVE MOVES THROUGH THE AREA...THUNDERSTORMS WILL PROBABLY STILL BE POSSIBLE IN THE SOUTHEAST SECTIONS FOR TUE NIGHT...SO WILL KEEP CHC POPS THERE. THIS SECOND WAVE SHOULD BE STRONG ENOUGH TO PUSH THE FRONT WELL SOUTH AND BRING A PERIOD OF DRY WEATHER TO THE AREA. UPPER LEVEL FLOW WILL ALSO BE OUT OF THE NORTHWEST...SO CONDITIONS SHOULD BE A TAD COOLER DURING THE DAY. CURRENT EXTENDED MODELS INDICATE THAT DRY WEATHER WILL PREVAIL THROUGH THURSDAY NIGHT AS MODELS DO NOT SHOW ANY SHORT WAVES MOVING THROUGH THE AREA DURING THAT PERIOD. HOWEVER...MODELS DO NOT DO WELL WITH SMALL WEAK FEATURES IN NORTHWEST FLOW SO DON`T BE SURPRISED IF THIS CHANGES OVER THE NEXT COUPLE OF DAYS. THE NEXT REAL CHANCE OF SHOWERS AND THUNDERSTORMS APPEARS NOT TO BE UNTIL FRIDAY THROUGH SATURDAY AS A MID LEVEL TROUGH MOVES TOWARD THE AREA. CURRENTLY THIS SYSTEM LOOKS TO REMAIN WEST OF THE AREA BUT STILL BRING PCPN TO ALL OF CENTRAL AND SOUTHEAST ILLINOIS FOR END OF THE WEEK. TEMPS WILL REMAIN AROUND NORMAL BUT THEN BECOME COOLER... POSSIBLY...AT THE END OF THE WEEK AND BEGINNING OF THE WEEKEND. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
318 AM CDT SUN JUL 21 2013 .SYNOPSIS... ISSUED AT 252 AM CDT SUN JUL 21 2013 A QUIET NIGHT ACROSS THE AREA WHILE THUNDERSTORMS RAIN OVER THE CENTRAL PLAINS. THE SURFACE AND 850 MB FRONTAL BOUNDARIES RESIDE TO OUR SOUTH IN NORTHERN MISSOURI AND ARE ASSOCIATED WITH WEAKENING STORMS. ANOTHER BOUNDARY TO OUR NORTH ACROSS MINNESOTA AND WISCONSIN IS ASSOCIATED WITH ACTIVE STORMS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 252 AM CDT SUN JUL 21 2013 MAIN CONCERN IN THIS TIME FRAME IS THUNDERSTORM CHANCES TODAY AND THIS EVENING. MODELS OTHER THAN THE RAP AND HRRR HAVE A WEAK HANDLE ON THE PLAINS CONVECTION. AND THIS SYSTEM WITH ITS ASSOCIATED SHORT WAVE TROUGH/MCV WILL BE OUR WEATHER MAKER FOR TODAY. OVERALL CURRENT CONVECTIVE TRENDS IN THE PLAINS ARE WEAKENING EXCEPT FOR REDEVELOPING STORMS ON THE TAIL OF THE MCS WHICH IS REACHING THE MISSOURI RIVER. TIMING OF THE SHORT WAVE INTO OUR AREA IS SUCH THAT THE ATMOSPHERE SHOULD DESTABILIZE THROUGH THE MORNING...ALBEIT WITH SUNSHINE FILTERED BY MID AND HIGH CLOUDS. MODELS SEEM TO WEAKEN THE WAVE...AND THE NAM EVEN TAKES IT SOUTH OF THE CWA. BUT THE ATMOSPHERE SHOULD BE PRIMED FOR CONVECTION... AND IF THE SURFACE AND 850MB FRONTS ARE PULLED NORTH WITH THE TROUGH...WE WILL HAVE A FOCAL POINT FOR STORM INITIATION. SINCE FLOW IS WEAK AND MODEL FORECASTS ARE DIVERGENT ON THIS ISSUE... HAVE GENERALLY HELD POPS IN THE HIGH CHANCE RANGE. SLOW MOVING STORMS COULD PRODUCE LOCALLY HEAVY RAIN...AND THE ENVIRONMENT SUPPORTS AN ISOLATED RISK OF DOWNBURSTS. MAX TEMPS TODAY RELATIVE TO YESTERDAY WILL BE HINDERED SOME BY CLOUD COVER. OVERNIGHT LOWS WILL BE MORE REFLECTIVE OF THE WARM SECTOR IN MISSOURI AS WINDS SHIFT TO THE SOUTH TONIGHT. WOLF .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 252 AM CDT SUN JUL 21 2013 THE DEEP MOIST AIR MASS AHEAD OF AN EARLY TUE FROPA WILL CONTINUE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS MONDAY INTO MONDAY NIGHT. DEVELOPING NW ALOFT AND HIGH PRESSURE TO THEN PROVIDE DRY WEATHER AND SLIGHTLY COOLER TEMPERATURES FOR MOST OF THE UPCOMING WORKWEEK. RAIN CHANCES RETURN LATE WEEK INTO THE WEEKEND WITH TEMPERATURES POSSIBLY TRENDING WELL BELOW NORMAL BY SUNDAY. MONDAY...WEAK MID LEVEL SUBSIDENCE AND LACK OF SIGNIFICANT SURFACE BOUNDARIES WILL BE UNFAVORABLE FOR ANYTHING BEYOND ISOLATED CONVECTION OVER MOST OF THE AREA AND HAVE LOWERED POPS TO SLIGHT CHANCES FOR MOST OF THE DAY. THE EXCEPTION IS ACROSS THE FAR NW...WHERE DEVELOPING LIFT AHEAD OF AN APPROACHING SHORTWAVE AND SURFACE COLD FRONT MAY LEAD TO THUNDERSTORMS DURING LATE DAY PEAK HEATING AND HAVE CHANCE POPS. PREFRONTAL WARMING AND WEDGE OF WARM AIR AT 850 MB WILL SUPPORT HIGHS FROM THE MID 80S NORTH TO AROUND 90 SOUTH. DEW POINTS IN THE UPPER 60S TO LOWER 70S MAY DRIVE HEAT INDEX READINGS INTO THE UPPER 90S ACROSS THE SOUTH. MONDAY NIGHT INTO EARLY TUESDAY...THERE IS A SIGNIFICANT SPREAD AMONG THE MODELS WITH THE TIMING OF THE SURFACE COLD FRONT. THE GFS HAS TRENDED THE SLOWEST...NOT BRINGING THE FRONT THROUGH UNTIL MID MORNING...WHILE THE ECMWF HAS THE SURFACE WIND SHIFT WELL BEFORE SUNRISE. WILL STAY CLOSER TO A FASTER CONSENSUS KEEPING CHANCE POPS FOCUSED ON THE OVERNIGHT PERIOD...FOLLOWED BY SLIGHT CHANCES OVER MAINLY THE EAST TUESDAY MORNING. WILL CONTINUE TO HAVE A THREAT FOR LOCALLY HEAVY RAINFALL DUE TO THE HIGH PW VALUES IN PLACE MONDAY NIGHT. KEPT MINS FROM THE MID 60S NORTH TO THE LOWER 70S SOUTH. TUESDAY THROUGH THURSDAY...CANADIAN HIGH PRESSURE BUILDS SOUTH INTO GREAT LAKES UNDER A NW FLOW ALOFT TO PROVIDE A PERIOD OF SEASONABLY MILD AND LESS HUMID CONDITIONS. WED LOOKS TO BE THE COOLEST AS THE POSITIONING OF THE PASSING HIGH WILL PROVIDE A LOW LEVEL NORTHEAST FETCH AND THE COOLEST TEMPERATURES AT 850 MB. THIS MAY RESULT IN HIGHS LIMITED TO THE 70S ACROSS THE CENTRAL AND NORTH...WHILE BOTH TUE AND THU WILL LIKELY SEE WIDESPREAD LOWER TO MID 80S. THIS SEASONABLY DRY AIR MASS WILL SUPPORT LOWS IN THE 60S WITH SOME POCKETS OF 50S POSSIBLE THU MORNING. GULF MOISTURE RETURNS TO THE REGION THU NIGHT INTO FRIDAY. THIS AND A COLD FRONT SHOWN PUSHING THROUGH FRIDAY NIGHT OR SATURDAY WILL BRING THUNDERSTORM CHANCES BACK TO THE AREA. THE LATEST GFS AND ECMWF THEN DEVELOP A SIGNIFICANT UPPER TROUGH OVER THE EASTERN U.S. THAT ALLOWS HIGH PRESSURE TO SPILL INTO THE MID MS VALLEY. THIS COULD LIMIT HIGHS TO THE 70S OVER THE WEEKEND WITH LOWS IN THE 50S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1142 PM CDT SAT JUL 20 2013 WINDS WILL REMAIN LIGHT EAST OR SOUTHEAST TONIGHT AND SUNDAY WITH WEAK HIGH PRESSURE REMAINING OVER THE WESTERN GREAT LAKES. WITH THE RAINS AT KDBQ THIS AFTERNOON AND WITH SCATTERED CLOUDS AND LIGHT WINDS OVERNIGHT THE MVFR VSBYS IN FOG WERE MAINTAINED FOR KDBQ LATE TONIGHT. TONIGHT SHOULD BE DRY FOR MOST OF THE THE FORECAST AREA. THERE IS A LOW CHANCE OF SOME SHRA/TSRA MOVING INTO THE HIGHWAY 20 CORRIDOR INCLUDING KDBQ EARLY SUNDAY MORNING OTHERWISE THE REST OF THE AREA SHOULD BE DRY THROUGH MUCH OF THE MORNING. SHRA/TSRA SHOULD DEVELOP OR SPREAD INTO THE AREA BY LATE MORNING WITH THE BEST CHANCE OF PRECIPITATION LATE SUNDAY AFTERNOON AND EVENING. FOR NOW HAVE JUST MENTIONED MVFR CONDITIONS IN TSRA LATE SUNDAY AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...WOLF SHORT TERM...WOLF LONG TERM...SHEETS AVIATION...DLF
AREA FORECAST DISCUSSION
NWS TOPEKA KS
353 AM CDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CDT SUN JUL 21 2013 TODAY AND TONIGHT...A LONGER WAVE LENGTH UPPER LEVEL TROUGH WILL CONTINUE TO AMPLIFY ACROSS THE UPPER MIDWEST AND GREAT LAKES STATES. THIS WILL CAUSE THE UPPER FLOW ACROSS THE PLAINS TO BECOME NORTHWESTERLY. SHORTER WAVE LENGTH UPPER LEVEL TROUGHS WILL ROUND THE UPPER RIDGE AXIS ACROSS THE WESTERN CONUS AND DIG SOUTHEAST ACROSS THE CENTRAL PLAINS THROUGH TONIGHT. A WEAK FRONTAL BOUNDARY WAS LOCATED FROM SOUTHWEST KS...NORTHEAST TO NEAR TOP...THEN NORTHEAST ACROSS NORTHERN MO. WEAK ISENTROPIC LIFT NORTH OF THE BOUNDARY MAY CAUSE A FEW SHOWERS TO DEVELOP THIS MORNING ACROSS EAST CENTRAL KS. MOST NUMERICAL MODELS SHOW AN H5 TROUGH DIGGING SOUTHEAST ACROSS CENTRAL HIGH PLAINS DURING THE AFTERNOON HOURS. THE ASCENT AHEAD OF THE H5 TROUGH COMBINED WITH UPSLOPE FLOW WILL CAUSE A COMPLEX OF THUNDERSTORMS TO DEVELOP ACROSS WESTERN NE LATE THIS AFTERNOON AND EARLY EVENING...THEN MOVE SOUTHEAST ACROSS EASTERN KS LATER TONIGHT. ISOLATED TO WIDELY SCATTERED THUNDERSTORMS MAY ALSO DEVELOP ALONG THE NORTHWARD MOVING FRONTAL BOUNDARY ACROSS THE CWA DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. THE 00Z NAM AND RAP MODELS WERE SHOWING 1500-2500 J/KG OF MLCAPE. HOWEVER...THE SFC-6KM EFFECTIVE SHEAR WILL ONLY BE 15 TO 20 KTS DURING THE AFTERNOON AND EARLY EVENING HOURS. DUE TO THE WEAKER VERTICAL WINDSHEAR UPDRAFTS WILL PROBABLY NOT BE ABLE TO SUSTAIN THEIR INTENSITY FOR MORE THAN 15 TO 20 MINUTES. THE STRONGER THUNDERSTORMS MAY PRODUCE SMALL HAIL AND 40 TO 50 MPH WINDS GUSTS. A STORM OR TWO MAY BRIEFLY PRODUCE QUARTER SIZE HAIL AND 58 MPH WINDS GUSTS. THE INSTABILITY AND VERTICAL WIND SHEAR AND INSTABILITY LOOKS TOO WEAK FOR THE COMPLEX OF THUNDERSTORMS LATE TONIGHT TO BE SEVERE...SOME OF THE STRONGER STORMS MAY PRODUCE GUSTY WINDS AND THERE COULD BE HEAVY RAINFALL ALONG THE TRACK OF THE THUNDERSTORM COMPLEX. I KEPT LIKELY POPS FOR THE NORTHERN AND EASTERN COUNTIES OF THE CWA AFTER MIDNIGHT. THIS MAY CHANGE DEPENDING TO WHERE THE MCS ACROSS NE FORMS AND HOW IT TRACKS THROUGH THE NIGHT. ATTM...MOST MODELS HAVE THE COMPLEX OF STORMS MOVING SOUTHEAST ACROSS SOUTH CENTRAL NE AND ACROSS THE EASTERN CWA LATE TONIGHT AND THROUGH THE MORNING HOURS OF SUNDAY. BROKEN TO SCATTED CLOUD COVER AND LIGHT SOUTHEAST WINDS WILL KEEP HIGH TEMPERATURES TODAY IN THE LOWER TO MID 90S ACROSS THE CWA. HIGHER SURFACE DEWPOINTS IN THE MID TO UPPER 60S WILL CAUSE HEAT INDICES TO RISE INTO THE UPPER 90S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 345 AM CDT SUN JUL 21 2013 SHORTWAVE TROUGHS EMBEDDED IN THE WEST TO NORTHWEST FLOW ALOFT WILL CONTINUE TO MOVE ACROSS THE AREA MAINTAINING A RATHER UNSETTLED PATTERN FOR PERIODIC CHANCES FOR THUNDERSTORMS. ALTHOUGH MONDAY MORNING MAY START DRY...MODELS ARE CONSISTENT WITH BACKING THE LLVL FLOW IN RESPONSE TO THE NEXT UPSTREAM WAVE. AS THIS OCCURS ISENTROPIC LIFT AND CONVERGENCE BEGIN TO INCREASE ACROSS MAINLY EAST CENTRAL AND NORTHEAST KS THROUGH THE DAY...SO THE POTENTIAL IS THERE FOR SOME ISOLATED DEVELOPMENT AS THE DAY PROGRESSES. INSTABILITY WILL BE VERY HIGH...SO ANY STORM THAT DOES DEVELOP COULD BE STRONG. LINGERING CLOUDS/ISOLATED CONVECTION MAY COMPLICATE STRONG WARM AIR ADVECTION AND HIGHS EAST. STILL EXPECT A WARM AND HUMID DAY WITH HIGHS IN THE MIDDLE TO UPPER 90S AND HEAT INDICES AROUND 100 DEGREES. BETTER COVERAGE OF THUNDERSTORMS IS EXPECTED INTO THE EVENING AND OVERNIGHT AS CONVECTION INCREASES ALONG THE FRONT TO THE NORTH IN RESPONSE TO THE SHORTWAVE TROUGH APPROACHING FROM THE NORTHWEST. WITH INCREASING FLOW ALOFT...SHEAR PROFILES WILL BE MORE SUPPORTIVE OF STRONGER CONVECTION WITH HAIL AND STRONG WINDS AS THE CONVECTION DEVELOPS/SPREADS SOUTHEASTWARD. HIGHS IN THE WAKE OF THE CONVECTION FOR TUESDAY WILL BE SIMILAR OR ONLY SLIGHTLY COOLER THAN MONDAY WITH READINGS IN THE LOW TO MIDDLE 90S AND LINGERING SLIGHT CHANCE FOR THUNDERSTORMS. A STRONGER SHORTWAVE WILL THEN MOVE THROUGH THE AREA TUESDAY NIGHT/EARLY WEDNESDAY WITH A BETTER CHANCE FOR MORE WIDESPREAD SHOWERS AND THUNDERSTORMS. IT WILL ALSO PROVIDE A STRONGER PUSH TO THE FRONT SOUTHWARD THROUGH THE CWA...SO COOLER HIGHS IN THE MIDDLE TO UPPER 80S ON TRACK FOR WEDNESDAY. CONVECTION SHOULD MOVE SOUTH AND EAST OF THE CWA BY WEDNESDAY AFTERNOON AND NIGHT BEFORE ANOTHER WAVE MOVES OUT OF THE ROCKIES AND INTO THE PLAINS IN THE THURSDAY NIGHT/FRIDAY TIMEFRAME WITH THE NEXT SIGNIFICANT CHANCE FOR THUNDERSTORMS. WILL KEEP A LINGERING LOW CHANCE FOR THUNDERSTORMS INTO SATURDAY...BUT BETTER CHANCES FOR PRECIP AT THAT TIME MAY OCCUR FURTHER TO THE WEST IN UPSLOPE FLOW OVER THE HIGH PLAINS. HIGHS WILL REMAIN GENERALLY IN THE 80S THROUGH THE END OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1156 PM CDT SAT JUL 20 2013 FOR THE 06Z TAFS...MAIN FOCUS IS ON THE POTENTIAL FOR ADDITIONAL SHOWERS AND THUNDERSTORMS TO DEVELOP NEAR THE TAF SITES. A COMPLEX OF THUNDERSTORMS WAS TRACKING SOUTHEAST ACROSS CENTRAL NEBRASKA...AND IF THIS ACTIVITY HOLDS TOGETHER IT IS EXPECTED TO PROGRESS INTO THE REGION DURING THE OVERNIGHT HOURS WITH SCATTERED PRECIPITATION PERSISTING THROUGH THE MORNING HOURS. HOWEVER...THERE IS STILL A UNCERTAINTY WITH REGARDS TO THE TIMING AND LOCATION OF ANY PRECIPITATION THAT DEVELOPS OVERNIGHT AND THROUGH THE DAY ON SUNDAY. CURRENTLY HAVE DRY CONDITIONS FOR THE AFTERNOON AND EVENING HOURS...BUT SOME MODELS SUGGEST SCATTERED ACTIVITY WILL PERSIST SO WILL CONTINUE TO MONITOR THIS POTENTIAL WITH FURTHER UPDATES. IN GENERAL...WINDS THROUGH THE PERIOD WILL BE OUT OF THE SOUTH AND SOUTHEAST...HOWEVER VARIABLE WINDS CAN BE EXPECTED IN AREAS OF THUNDERSTORM DEVELOPMENT. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GARGAN LONG TERM...63 AVIATION...HENNECKE
AREA FORECAST DISCUSSION
NWS JACKSON KY
142 AM EDT SUN JUL 21 2013 .UPDATE... ISSUED AT 142 AM EDT SUN JUL 21 2013 MADE A FEW TWEAKS TO THE FORECAST FOR THE 24 HOUR PERIOD BEGINNING WITH 12Z TODAY. TRIED TO CAPTURE THE EVOLUTION OF ONGOING SHOWER AND STORM ACTIVITY THAT IS MOVING ACROSS CENTRAL KENTUCKY. THE MODELS HAVE ALL PRODUCED VERY DIFFERENT SOLUTIONS REGRADING TIMING OF SHOWER AND STORM ACTIVITY AND OVERALL AREAL COVERAGE. IN THE END...DECIDED TO GO WITH A MODIFIED VERSION OF THE LATEST NAM12 AND SREF MODEL RUNS. OVERALL IT WILL BE QUITE CHALLENGING TO DETERMINE WHEN AND WHERE SHOWERS AND STORMS WILL FORM ACROSS THE AREA AND HOW THEY WILL PROGRESS ONCE THEY HAVE FORMED. MADE TWEAKS TO THE SKY COVER...QPF...AND WEATHER GRIDS FROM 12Z ONWARD. WILL TAKE A LOOK AT THE OTHER FORECAST ELEMENTS ONCE THE TAF DISCUSSION HAS BEEN ISSUED. OVERALL IT APPEARS THAT SCATTERED TO NUMEROUS SHOWERS AND STORMS WILL MOVE ACROSS EASTERN KENTUCKY DURING THE DAY TIME HOURS...WITH LOCALLY HEAVY RAINFALL AND GUSTY WINDS POSSIBLE WITH SOME OF THE STORMS. THE CULPRIT FOR ALL THIS WEATHER WILL BE A COLD FRONT THAT IS EXPECTED TO MOVE SLOWLY SOUTHWARD ACROSS THE AREA TODAY. UPDATE ISSUED AT 1025 PM EDT SAT JUL 20 2013 MOST SHOWERS AND THUNDERSTORMS HAVE DIMINISHED TO OUR NORTH AND EAST. HOWEVER...A LARGE LINE OF WEAK CONVECTION HAS DEVELOPED TO OUR WEST AND CONTINUES TO SLOWLY MAKE ITS WAY EASTWARD. EXPECT SOME CONTINUED WEAKENING BY THE TIME IT REACHES EASTERN KY...THOUGH LOW END CHANCES/SCT COVERAGE IS STILL WARRANTED BASED ON LATEST MODEL RUNS. UPDATED POPS TO REFLECT THIS LATEST RADAR TREND...WITH SCT CHANCES MOVING IN ACROSS THE WESTERN CWA IN THE NEXT COUPLE OF HOURS...AND THEN SPREADING ACROSS THE REMAINING CWA BY LATE TONIGHT. UPDATE ISSUED AT 527 PM EDT SAT JUL 20 2013 BASED ON CURRENT RADAR TRENDS...DIDN/T FEEL CONFIDENT IN NO POPS ACROSS THE AREA THIS AFTERNOON/EVENING. WENT AHEAD AND ADDED IN SOME SLIGHT CHANCES ALONG THE NORTHERN AND SOUTHEASTERN SECTIONS OF THE CWA THROUGH THIS AFTERNOON IN CASE SOME SHORT LIVED CONVECTION DEVELOPS. THEN HAVE ISOLATED CHANCES TAPERING OFF ACROSS THE SOUTHEAST THIS EVENING AS BEST INSTABILITY BECOMES FOCUSED OVER THE NORTHERN CWA WITH AN IMPOSING COLD FRONT AND AREA OF CONVECTION MOVING INTO THE REGION. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 325 PM EDT SAT JUL 20 2013 CONTINUING TO WATCH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DROPPING SOUTHWARD ACROSS THE OHIO RIVER VALLEY. A GAP IN THE LINE HAS OPENED UP JUST TO OUR NORTH. WHILE SHOWERS AND STORMS ARE STILL POSSIBLE THIS EVENING INTO TONIGHT...EVERY HRRR RUN OVER THE PAST SEVERAL HOURS CONTINUES TO BACK OFF ON OVERALL COVERAGE ACROSS EASTERN KENTUCKY THIS EVENING...WITH EVERYTHING FADING AWAY AROUND SUNSET. THUS...HAVE DECREASED POPS INTO THIS EVENING AND THE OVERNIGHT HOURS. THIS TREND MAY HAVE TO BE CONTINUED ON THE EVENING SHIFT IF THE TRENDS CONTINUE THE WAY THEY ARE HEADING. REGARDLESS...THE PROSPECTS FOR WIDESPREAD SHOWERS AND THUNDERSTORMS IS DRASTICALLY LESS NOW. WILL MAINTAIN LOW 20-30 POPS THROUGH THE OVERNIGHT HOURS. WITH THE BOUNDARY WASHED OUT OVER THE AREA TOMORROW...DAYTIME HEATING SHOULD ALLOW FOR QUICK REDEVELOPMENT AFTER SUNRISE. COVERAGE SHOULD BE DECENT TOMORROW...SO OPTED TO STAY WITH OUR 60-70 POPS. THERE IS SOME QUESTION AS TO HOW MUCH ACTIVITY WILL THEN LINGER INTO TOMORROW NIGHT AS THE QUASI BOUNDARY MAY SHIFT BACK TO THE NORTH. LACK OF OVERNIGHT INSTABILITY MAY KEEP THINGS FAIRLY LOW KEY FOR MUCH OF THE NIGHT. THERE IS A SHORTWAVE TROUGH PUSHING ACROSS THE AREA LATE IN THE NIGHT THAT COULD ACT TO FIRE OFF SOME SHOWERS AND THUNDERSTORMS...SO WILL INCREASE POPS THROUGH THE NIGHT. TEMPERATURES ON SUNDAY SHOULD BE SLIGHTLY LOWER WITH THE INCREASED CLOUD COVER AND PRECIPITATION. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 325 PM EDT SAT JUL 20 2013 THE MODELS BASICALLY AGREE ON THE GENERAL MID LEVEL PATTERN THROUGH THE BULK OF THE EXTENDED FORECAST. A TROUGH WILL DEVELOP THROUGH THE OHIO VALLEY INITIALLY AS ENERGY FROM THE NORTHERN PLAINS POOLS OVER THE REGION. THIS TROUGH EVOLVES GRADUALLY AS A COUPLE OF CYCLES OF WAVES MOVE THROUGH THE OHIO VALLEY...EACH DEPICTED SLIGHTLY DIFFERENT BY THE MODELS. THIS SEMI-STATIONARY TROUGH BOTTOMS OUT ON THURSDAY PER A CONSENSUS OF SOLUTIONS. EACH MODEL HAS ENOUGH OF A DIFFERENT HANDLING OF THE INDIVIDUAL WAVES THAT A BLENDED APPROACH IS PREFERRED FOR EXTENDED FORECASTING PURPOSES. IT DOES LOOK LIKE HEIGHTS WILL RISE A BIT ON FRIDAY AS THE CORE OF THE TROUGH SHIFTS TEMPORARILY EAST BUT THE ECMWF IS MOST AGGRESSIVE IN TAKING ANOTHER DECENT WAVE FROM THE PLAINS EAST INTO THE OHIO VALLEY FOR THE WEEKEND LIKELY RESTORING THE TROUGH FOR THE OHIO VALLEY. THE GFS HAS A VERSION OF THIS THAT ALSO LOWERS HEIGHTS OVER THE OHIO VALLEY ON SATURDAY...BUT DOES SO BY RELYING ON WAVES FURTHER NORTH THAN THE ECMWF...MAINLY MOVING THEM THROUGH THE GREAT LAKES. AGAIN HERE... WILL FAVOR A CONSENSUS SOLUTION FOR WEATHER DETAILS. SENSIBLE WEATHER WILL FEATURE A VERY UNSETTLED SITUATION TO START THE EXTENDED AS MID LEVEL WAVES ACTIVATE SHOWERS AND THUNDERSTORMS ALONG AND SOUTH OF A FRONTAL BOUNDARY RUNNING JUST NORTH OF THE OHIO RIVER. THERE WILL BE PLENTY OF HIGH PW AIR IN PLACE TO SUPPORT THE STORMS AND THUS A HEAVY RAIN POTENTIAL WILL EXIST THROUGH THE DAY...MONDAY. THE NEXT SFC BOUNDARY WILL APPROACH THE AREA ON TUESDAY CONTINUING OUR CHANCES OF SHOWERS AND THUNDERSTORMS. THIS CONVECTION IS EXPECTED TO LINGER INTO THE NIGHT WHEN THE BOUNDARY DROPS THROUGH THE CWA IN THE FORM OF A COLD FRONT. FOR THURSDAY AND FRIDAY...ANY CONVECTION SHOULD BE AT A MINIMUM IN THE WAKE OF THE SFC FRONT AND SLIGHTLY HIGHER HEIGHTS ALOFT. HOWEVER...THE NEXT SFC SYSTEM LOOKS TO BRING A RENEWED CHANCE OF CONVECTION TO THE AREA ON SATURDAY...SPURRED ON BY FALLING HEIGHTS AND MORE INBOUND MID-LEVEL ENERGY. THE CR GRID LOAD CAME IN PRETTY GOOD CONSIDERING THE SMALLER SCALE DIFFERENCES AMONG THE MODELS WITH RESPECT TO WEATHER DETAILS THROUGH THE EXTENDED. DID NUDGE DOWN POPS A BIT LATE IN THE FORECAST...MORE TOWARD THE OPERATIONAL ECMWF. ALSO...ADJUSTED OVERNIGHT LOWS A TAD FOR WEDNESDAY AND THURSDAY NIGHT TO BETTER EMPHASIZE RIDGE AND VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 142 AM EDT SUN JUL 21 2013 A WEAK COLD FRONT WILL PUSH SOUTHEAST AND STALL OVER NORTHERN KENTUCKY THROUGH THE REMAINDER OF THE OVERNIGHT. SCATTERED SHOWERS AND STORMS CONTINUE TO FIRE IN WESTERN AND CENTRAL TENNESSEE AND CENTRAL KENTUCKY. THESE SHOWERS AND STORMS WILL GRADUALLY MAKE THERE WAY INTO THE FORECAST AREA OVERNIGHT...AND SHOULD INCREASE IN COVERAGE ONCE THE SUN COMES UP AND A COLD FRONT SITUATED TO OUR NORTH BEGINS TO MOVE SOUTHWARD OUT OF THE OHIO VALLEY. SHOWERS AND STORMS ARE EXPECTED TO PERSIST THROUGH THE AFTERNOON AND EVENING HOURS TODAY...AS THE AFOREMENTIONED COLD FRONT EVOLVES INTO A WARM FRONT AND BEGINS TO DRIFT NORTHWARD ACROSS THE AREA. IN GENERAL...VFR CONDITIONS WILL PREVAIL AT THE TAF SITES FOR THE REST OF THE NIGHT. CONDITIONS WILL BEGIN TO DETERIORATE A BIT AS SHOWERS AND STORMS BECOME MORE NUMEROUS DURING THE DAY...WITH MVFR CONDITIONS POSSIBLE AT TIMES. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...KAS LONG TERM...GREIF AVIATION...AR
AREA FORECAST DISCUSSION...UPDATED
NWS PADUCAH KY
1200 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 1155 PM CDT SAT JUL 20 2013 UPDATED THE AVIATION SECTION FOR THE 06Z TAF ISSUANCE. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... ISSUED AT 200 PM CDT SAT JUL 20 2013 18Z MESOANALYSIS SHOWS A COLD FRONT EXTENDING WESTWARD ACROSS CENTRAL INDIANA TO A WEAK SURFACE LOW OVER CENTRAL ILLINOIS. A SURFACE TROUGH EXTENDS SOUTHWEST FROM THE LOW CENTER TO NEAR KFAM AND THEN BETWEEN KUNO/KPOF. DEW POINTS POOLING INTO THE LOWER AND MID 70S ALONG THE TROUGH AND COLD FRONT HAVE CONTRIBUTED TO VERY UNSTABLE CAPES LOCALLY OVER 3000 J/KG. ISOLATED STORMS HAVE POPPED UP ALONG THE SURFACE TROUGH OVER MISSOURI...WHILE LARGER CLUSTERS OF STORMS ARE EAST OF THE SURFACE LOW CENTER IN INDIANA/EAST CENTRAL IL. THROUGH THE EVENING HOURS...THE COLD FRONT IS FORECAST TO DRIFT SOUTH TO THE INTERSTATE 64 CORRIDOR WHILE THE SURFACE TROUGH REMAINS STATIONARY OVER THE MISSOURI OZARKS. THE LATEST HRRR MODEL REFLECTIVITY INDICATES THAT CLUSTERS OF STORMS /POSSIBLE MCS/ WILL PROPAGATE SOUTH ALONG THE WABASH VALLEY...REACHING THE PENNYRILE REGION OF WESTERN KY THIS EVENING. THIS SCENARIO IS SUPPORTED BY THE 12Z HIGH RES NMM. OTHER ISOLATED STORMS MAY DEVELOP EASTWARD FROM THE SURFACE TROUGH OVER MISSOURI. VERY LIMITED SHEAR MAGNITUDE WILL LIMIT SEVERE POTENTIAL TO ISOLATED PULSE EVENTS...THOUGH AN ORGANIZED COLD POOL COULD DEVELOP WITH THE WABASH VALLEY MCS. ACTIVITY WILL WEAKEN SIGNIFICANTLY BY 06Z AS THE BOUNDARY LAYER COOLS AND STABILIZES. ON SUNDAY...THE SURFACE FRONT IS FORECAST TO SLOWLY LIFT BACK NORTH AS A WARM FRONT. A MINOR 500 MB SHORTWAVE WILL MOVE EAST/SOUTHEAST ACROSS THE MISSISSIPPI VALLEY. THIS SHORTWAVE WILL HELP REJUVENATE CONVECTION ALONG AND SOUTH OF THE FRONT...ESPECIALLY DURING THE WARMER AND MORE UNSTABLE AFTERNOON HOURS. HIGH TEMPS WILL STRUGGLE TO REACH THE UPPER 80S DUE TO ABUNDANT CLOUDINESS AND CONVECTION. ON SUNDAY NIGHT...A RATHER WELL DEVELOPED 500 MB SHORTWAVE FOR MID SUMMER WILL APPROACH FROM THE CENTRAL PLAINS. THIS SHORTWAVE WILL TAP A VERY MOIST AND UNSTABLE SOUTHWEST WIND FLOW. SHOWERS AND STORMS ARE LIKELY OVERNIGHT INTO MONDAY MORNING...UNTIL THE PASSAGE OF THE SHORTWAVE. ONCE AGAIN...SEASONABLY WEAK SHEAR PROFILES WILL LIMIT THE POTENTIAL HAZARDS TO MAINLY HEAVY RAIN AND FREQUENT LIGHTNING. ON MONDAY AFTERNOON AND MONDAY NIGHT...PRECIP COVERAGE WILL GRADUALLY DECREASE WITH THE PASSAGE OF THE SHORTWAVE. 850 MB WARM ADVECTION WILL BE COUNTERED BY EXTENSIVE CLOUD COVER AND PRECIP... SO DAYTIME HIGHS ON MONDAY WILL ONLY BE NEAR SEASONAL NORMS. OVERNIGHT LOWS WILL BE NEAR SURFACE DEW POINTS IN THE LOWER 70S. .LONG TERM /TUESDAY THROUGH SATURDAY/... ISSUED AT 200 PM CDT SAT JUL 20 2013 THE MODELS ARE IN A LITTLE BETTER AGREEMENT WITH THE TIMING OF THE MID WEEK FRONT. THIS FRONT WILL PROVIDE THE FOCUS FOR THUNDERSTORMS TUESDAY THEN TAPERING OFF INTO WEDNESDAY. WEAK HIGH PRESSURE WILL DRY US OUT FOR AT LEAST THURSDAY AND FRIDAY WITH AT LEAST A CHANCE RETURNING FRIDAY NIGHT INTO SATURDAY AS YET ANOTHER COLD FRONT ENTERS THE PICTURE AT THE SAME TIME A WARM FRONT TRIES TO LIFT OUT OF THE PLAINS INTO THE REGION. THE LATEST RUNS WOULD HAVE THE COLD FRONT WINNING OUT AND SUPPRESSING THE WARM FRONT TO THE SOUTHWEST. HOWEVER...THE SIGNALS ARE VERY WEAK AND MAY FLIP FLOP WITH LATER RUNS. THIS WOULD ALSO RESULT IN A SIGNIFICANT CHANGE FOR TEMPS THIS WEEKEND. EITHER WAY ONE SYSTEM OR THE OTHER WILL PROVIDE A CHANCE FOR THUNDERSTORMS. AS FOR TEMPS FOLLOWED THE ONGOING TREND WITH THE WARMEST DAY TUESDAY THEN COOLING AND A BIT DRIER LATE IN THE WEEK. TEMPS BEGIN TO SOAR BACK TO AROUND 90 LATE IN THE WEEK AHEAD OF THE APPROACHING COLD FRONT. IF THE WEEKEND COLD FRONT MAKES IT THROUGH THE AREA WE WILL COOL BACK INTO THE 80S AGAIN HOWEVER SHOULD THE WARM FRONT OVERTAKE THE REGION WILL HAVE TO ADJUST TEMPS UP FROM CURRENT FORECAST. && .AVIATION... ISSUED AT 1155 PM CDT SAT JUL 20 2013 POSSIBLE MVFR FOG BETWEEN 08-12Z...OTHERWISE VFR CONDITIONS SHOULD PREVAIL THROUGH MOST OF THE PERIOD. VCSH/VCTS POSSIBLE AFT 13Z. POSSIBLE MVFR CIGS/VSBYS IN TSRA AFT 00Z. LIGHT AND VARIABLE WINDS WILL BECOME SOUTHWEST AOB 10 KTS AFT 13Z. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ PUBLIC...DB AVIATION...JP
AREA FORECAST DISCUSSION
NWS CARIBOU ME
108 AM EDT SUN JUL 21 2013 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE REGION OVERNIGHT. A DRIER AND COOLER CANADIAN AIR MASS WILL THEN BUILD INTO THE AREA ON SUNDAY AND HOLD OVER THE REGION THROUGH MONDAY. THE NEXT LOW PRESSURE FROM THE GREAT LAKES WILL APPROACH THE REGION LATE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH SUNDAY/... 105 AM UPDATE...NO SIGNIFICANT CHANGES WERE NEEDED FOR THIS UPDATE. DRIER AIR CONTINUES TO SPILL INTO THE FORECAST AREA, WITH DEWPOINTS DROPPING INTO THE 40S AND 50S. AS SUCH, TONIGHT WILL BE A MUCH COOLER AND MORE COMFORTABLE NIGHT. SKIES HAVE BECOME CLEAR OVER ALL BUT THE FAR DOWNEASTERN AREAS, AND THESE CLOUDS SHOULD PUSH OFFSHORE BY DAWN. THE GOING FORECAST HAS THIS ALL COVERED, SO ONLY MADE SLIGHT ADJUSTMENTS TO MIN TEMPS TO MATCH CURRENT OBS. PREVIOUS DISCUSSION... A COLD FRONT WILL MOVE THROUGH THE REGION OVERNIGHT FOLLOWED BY CANADIAN HIGH PRES FOR SUNDAY. THIS HIGH WILL REMAIN IN CONTROL THROUGH EARLY NEXT WEEK. SOME CONVECTION HAS FIRED UP MAINLY ACROSS NORTHERN AND WESTERN AREAS(SUB-SEVERE) AS SOME UPPER LEVEL DIVERGENCE SEEN ON THE SATL WV IMAGERY AND 12Z UA. THE BEST SHOT FOR ANY STRONGER STORMS WILL BE ACROSS THE DOWNEAST AND COAST INTO THE EVENING AND THEN ACTIVITY WILL WEAKEN. THE BEST FORCING AND INSTABILITY WILL SHIFT TO THE EAST. ADDED SOME FOG TO THE GRIDS FOR TONIGHT INTO EARLY SUNDAY MORNING BASED ON ANTICIPATED CLEARING AND COOLER TEMPERATURES W/A WET GROUND. ADJUSTED THE OVERNIGHT LOW USING A BLEND OF THE NAM12 AND ECMWF. POPS ARE A BLEND OF THE RUC AND DOWNSCALED NAM WHICH SHOW PRECIP CHANCES WINDING DOWN AFTER 00Z. SUNDAY LOOKS TO BE SUNNY AND PLEASANT W/HIGH PRES BUILDING IN FROM CANADA. THINKING ATTM IS TO TAKE W/CONSISTENCY AND KEEP THE MIDNIGHT CREW`S MAXES OF LOWER 70S NORTHERN CWA AND MID TO UPPER 70S CENTRAL AND DOWNEAST. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... HIGH PRESSURE WILL SETTLE OVER THE AREA SUNDAY NIGHT. WITH LIGHT WINDS...CLEAR SKIES AND RELATIVELY DRY AIR THE NIGHT WILL BE COOL WITH LOWS DROPPING INTO THE 40S NORTH TO NEAR 50 DOWNEAST. THIS WILL BE FOLLOWED BY A MOSTLY SUNNY AND SEASONABLE DAY ON MONDAY. CLOUDS WILL BEGIN TO INCREASE FROM THE SOUTHWEST LATE IN THE DAY AS MOISTURE LIFTS NORTH FROM LOW PRESSURE TRACKING INTO SOUTHERN NEW ENGLAND. CLOUDS WILL CONTINUE TO INCREASE MONDAY NIGHT AND SOME RAIN MAY SPREAD INTO THE AREA LATE. THE BEST CHANCE FOR RAIN WILL BE ALONG THE FRONTAL BOUNDARY WHICH WILL BE NEAR THE COAST. THE LOW WILL TRACK JUST OFFSHORE ON TUESDAY BRINGING A CHANCE OF RAIN TO THE AREA. THE BEST CHANCE FOR RAIN WILL BE ALONG COASTAL AREAS. A COLD FRONT WILL APPROACH THE WEST LATE IN THE DAY. WARM AND HUMID AIR MOVING NORTH AHEAD OF THE FRONT BENEATH RELATIVELY COOLER AIR ALOFT MAY PRODUCE SOME THUNDERSTORMS IN WESTERN AREAS LATE IN THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... A WEAK LOW WILL BE TRACKING OFF THE COAST TUESDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE LOW MAY BRING SOME RAIN TO COASTAL AREAS EARLY TUESDAY NIGHT WHILE THE APPROACHING FRONT BRINGS SOME SHOWERS AND POSSIBLY THUNDERSTORMS TO FAR WESTERN AREAS. THE FRONT IS EXPECTED TO CROSS THE AREA EARLY WEDNESDAY BRINGING SOME SHOWERS AND ISOLATED THUNDERSTORMS MAINLY TO THE DOWNEAST REGION. HIGH PRESSURE SHOULD THEN BRING DRIER AIR WITH CLEARING LATER WEDNESDAY INTO THURSDAY. ANOTHER FRONT MAY APPROACH LATER FRIDAY INTO SATURDAY WITH INCREASED HUMIDITY FRIDAY INTO SATURDAY. && .AVIATION /05Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR THROUGH SUNDAY. SHORT TERM: VFR CONDITIONS ARE EXPECTED SUNDAY NIGHT INTO MONDAY WITH HIGH PRESSURE AND MOSTLY CLEAR SKIES. CONDITIONS WILL LIKELY BEGIN VFR MONDAY NIGHT BUT MAY LOWER TO MVFR OR IFR LATE AS LOW CLOUDS AND SHOWERS MOVE IN. MVFR CONDITIONS ARE EXPECTED TUESDAY NIGHT INTO EARLY WEDNESDAY. HIGH PRESSURE MAY THEN BRING AN IMPROVEMENT TO VFR WEDNESDAY INTO EARLY FRIDAY. LOWERING CLOUDS AND SHOWERS MAY LOWER CONDITIONS TO MVFR FRIDAY NIGHT INTO SATURDAY AS THE NEXT FRONT MOVES IN. && .MARINE... NEAR TERM: SEAS RUNNING AROUND 4 FT AT THE EASTERN MAINE SHELF THIS EVENING. WINDS ARE EXPECTED TO BECOME GUSTY W/THE COLD FRONT TONIGHT W/SPEEDS OF 25 KT BRIEFLY. THE WINDS WILL SUBSIDE ON SUNDAY DOWN TO 10 KT AS HIGH PRES PUSHES E. SHORT TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE SHOULD BRING CLEAR AND PLEASANT CONDITIONS SUNDAY INTO MONDAY. LOWER CLOUDS...FOG AND SOME RAIN MAY MOVE OVER THE WATERS ON TUESDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HASTINGS/HEWITT SHORT TERM...BLOOMER LONG TERM...BLOOMER AVIATION...HASTINGS/HEWITT/BLOOMER MARINE...HASTINGS/HEWITT/BLOOMER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
451 AM EDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 450 AM EDT SUN JUL 21 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A ZONAL FLOW OVER THE UPPER GREAT LAKES. AT THE SFC...HIGH PRESSURE DOMINATES THE UPPER GREAT LAKES. THE CLEAR SKIES AND LIGHT WINDS HAVE ALLOWED TEMPS EARLY THIS MORNING TO FALL INTO THE 40S WITH EVEN A FEW LOCATIONS REACHING THE MID TO UPPER 30S. TODAY...AS THE SFC HIGH SHIFTS EAST OF THE AREA...SRLY FLOW AND WAA WILL INCREASE AHEAD OF APPROACHING SHORTWAVE AND FRONTAL SYSTEM OVER THE NRN PLAINS. TEMPS SHOULD CLIMB INTO THE LOWER TO MID 70S INLAND WITH LOWER READINGS IN THE MID TO UPPER 60S ALONG THE GREAT LAKES. MODELS INDICATE SOME INCREASE IN 305K ISENTROPIC ASCENT OVER FAR WRN UPR MI LATE IN THE DAY ALTHOUGH BEST MOISTURE LIFT SHOULD STAY SOUTH AND WEST. WILL MAINTAIN GOING FCST OF SLIGHT CHANCE POPS OVER THE FAR WEST. TONIGHT...INCREASING 925-700 MB THETA-E ADVECTION AND 305K ISENTROPIC ASCENT SHOULD LEAD TO INCREASED CHCS FOR SHRA AND TSRA ESPECIALLY AFT MIDNIGHT AS SHORTWAVE APPROACHED FM THE WEST. LIMITING FACTOR FOR TSRA WILL BE LACK OF ELEVATED INSTABILITY AS MUCAPES ONLY A FEW HUNDRED J/KG. WILL KEEP HIGHER CHC POPS OVER FAR WEST AND TAPER TO LOW CHC 20-30 PCT POPS OVER CENTRAL COUNTIES. EXPECT LOWS GENERALLY IN THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 450 AM EDT SUN JUL 21 2013 MOST TIME SPENT ON LONG TERM WAS WITH PRECIP CHANCES MON/MON NIGHT AND ASSESSING SEVERE STORM THREAT FOR MON AFTERNOON/EVENING. LOOKING FIRST AT THE LARGE SCALE...AN UPPER TROUGH OVER THE ERN HALF OF THE CONUS WILL BE STEMMING FROM A CLOSED LOW OVER NRN QUEBEC AND AN UPPER RIDGE WILL BE OVER THE WRN CONUS AT 12Z MON. A PIECE OF UPPER ENERGY WILL MOVE ACROSS THE REGION MON INTO EARLY MON NIGHT...FOLLOWED BY OTHER SMALLER SCALE ENERGY THU NIGHT THROUGH SAT...BUT THE OVERALL PATTERN REMAINS SIMILAR THROUGH THE EXTENDED. THIS MEANS...FOR THE MOST PART...THAT COOLER WEATHER IS HERE TO STAY FOR MUCH OF THE NEXT WEEK AT LEAST. FOR THE SPECIFICS... MON/MON NIGHT...THERE WILL BE PRECIP MOVING INTO THE WRN CWA EARLY MON AS THE UPPER TROUGH AND SFC TROUGH/COLD FRONT MOVE IN. THINK THE BEST PRECIP CHANCES WILL BE DURING THE AFTERNOON/EARLY EVENING AS THE COLD FRONT MOVES THROUGH A POTENTIALLY UNSTABLE AIRMASS. QUESTIONS IS HOW MUCH CLEARING WILL RESULT AFTER MORNING RAIN...WHICH WILL EFFECT HOW MUCH INSTABILITY EXISTS IN THE AFTERNOON. IF WE CAN GET GOOD CLEARING...SBCAPE VALUES MAY BE 800-1200J/KG /HIGHEST OVER SCENTRAL UPPER MI/...AND STRONGLY VEERING WINDS THROUGH THE ATMOSPHERE WILL LEAD TO AROUND 40KTS OF 0-6KM BULK SHEAR. IF OPTIMAL CONDITIONS FOR CONVECTION DO MATERIALIZE...THEN SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS WOULD BE POSSIBLE...WITH THE BEST CHANCES OVER SCENTRAL UPPER MI. HOWEVER...AT THIS TIME...THINK THE COVERAGE OF ANY SEVERE WEATHER WILL BE MORE LIMITED DUE TO DRY AIR. FOR NOW WILL CONTINUE MENTION OF SEVERE CHANCES IN HWO/EHWO BUT STILL TOO UNCERTAIN TO PUT IN GRIDS. MON LOOKS LIKE THE WARMEST DAY IN THE NEXT WEEK AHEAD OF THE COLD FRONT...WITH HIGHS IN THE 70S TO MID 80S. POSTFRONTAL TUESDAY SHOULD BE COOLER AND SIMILAR TO YESTERDAY...WITH HIGHS AROUND 60 NEAR LAKE SUPERIOR TO THE LOW 70S SOUTH CENTRAL. SKIES SHOULD BE CLEARING BY THE AFTERNOON. WED WILL BE SLIGHTLY WARMER THAN TUESDAY AS TEMPS RECOVER SOME FROM THE COLD FRONT. SHOULD SEE SOME INCREASE IN CLOUDS FROM W TO E DURING THE AFTERNOON/EVENING AS A MORE MILD PIECE OF UPPER ENERGY SLIDES ACROSS THE CWA...BUT NO PRECIP IS EXPECTED. THERE IS MORE UNCERTAINTY LATER IN THE WEEK WHEN LOOKING AT MORE SIGNIFICANT UPPER ENERGY SLIDING INTO THE REGION...BUT PRECIP WILL CERTAINLY BE POSSIBLE LATER INTO THE WEEK. TEMPERATURES WILL CLIMB ANOTHER COUPLE OF DEGREES ON THURSDAY...BUT SHOULD AGAIN FALL INTO THE WEEKEND AS THE UPPER TROUGH MOVES OVERHEAD. USED A GENERAL CONSENSUS OF MODEL GUIDANCE FOR THIS PART OF THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 141 AM EDT SUN JUL 21 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD AS HIGH PRESSURE REMAINS OVER THE REGION. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 450 AM EDT SUN JUL 21 2013 HIGH PRESSURE WILL KEEP WINDS GENERALLY LIGHT TODAY OVER THE NORTHERN GREAT LAKES. SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS LATE TONIGHT AND MONDAY AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND THE TROUGH/COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS TUE NIGHT THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...TITUS AVIATION...07 MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
141 AM EDT SUN JUL 21 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 419 PM EDT SAT JUL 20 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NE CANADA AND A WEAK RIDGE INTO MANITOBA RESULTING IN CONFLUENT WNW FLOW THROUGH THE NRN GREAT LAKES. AT THE SFC...A RIDGE EXTENDED FROM SRN MANTIOBA INTO NW ONTARIO TO NW LAKE SUPERIOR. ABUNDANT DIRUNAL CU HAD DEVELOPED IN THE COOL AIR TO THE NORTH OF LAKE SUPERIOR WHERE 850 MB TEMPS WERE DOWN TO 2C-3C. FARTHER SOUTH...VIS LOOP SHOWED ONLY SCT CU OVER THE W HALF OF UPPER MI. TONIGHT...WITH CLEAR SKIES AND LIGHT WINDS TONIGHT...FAVORABLE RADIATIONAL COOLING CONDITIONS IN THE DRY AIRMASS OVER THE REGION (PWAT BELOW 0.50 INCH)WILL ALLOW TEMPS TO DROP TO NEAR THE LOW END OF GUIDANCE...NEAR 40 OVER THE COLDER INLAND LOCATIONS. SUN...AS THE SFC HIGH SHIFTS EAST OF THE AREA AND THE MID LEVEL FLOW BECOMES MORE ZONAL...SRLY FLOW AND WAA WILL INCREASE AHEAD OF APPROACHING SHORTWAVE AND FRONTAL SYSTEM OVER THE NRN PLAINS. TEMPS SHOULD CLIMB INTO THE LOWER TO MID 70S INLAND WITH LOWER READINGS IN THE MID TO UPPER 60S ALONG THE GREAT LAKES. MODELS SUGGEST THAT THE GREATEST INCREASE IN MOISTURE AND STRONGER 300-310K ISENTROPIC LIFT WILL REMAIN TO THE SOUTH AND WEST OF UPPER MI FROM SRN MN INTO CNTRL WI LATE SUN AFTERNOON. SO...THE FCST MAINTAINS ONLY SLIGHT CHANCE POPS INTO THE FAR WEST .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 419 PM EDT SAT JUL 20 2013 UPPER AIR PATTERN THROUGH NEXT WEEK DRIVEN BY TWO AREAS OF LOWER HEIGHTS...ONE OVER GULF OF ALASKA/BRITISH COLUMBIA AND THE OTHER VCNTY OF HUDSON BAY ACROSS QUEBEC. IN BTWN THESE TWO...WNW FLOW HOLDS IN PLACE FROM WESTERN CANADA ACROSS GREAT LAKES. MOST PERSISTENT RIDGING WILL BE LIMITED TO SOUTHWEST PART OF CONUS. PATTERN DOES NOT LOOK APPRECIABLY WARM...ESPECIALLY COMPARED TO THE RECENT HEAT WAVE THAT AFFECTED GREAT LAKES REGION. OVERALL TEMPS THROUGH THE PERIOD WILL BE AT OR SLIGHTLY BLO NORMAL /NORMAL HIGH TEMPS ON AVERAGE THIS TIME OF YEAR ARE IN THE UPR 70S NORTH TO LOWER 80S SOUTH/. WARMEST DAY MOST LIKELY ON MONDAY AS WARM FRONT LIFTS ACROSS UPPER LAKES RESULTING IN SW SFC WINDS. COLD FRONT MOVES IN MONDAY NIGHT THOUGH...MAKING THIS STAY IN THE WARM SECTOR VERY BRIEF. SHRA/TSRA POSSIBLE AS THESE FRONTAL BOUNDARIES AFFECT THE AREA. ONLY OTHER CHANCE OF RAIN ARRIVES LATER THURSDAY INTO FRIDAY AS ANOTHER SFC TROUGH CROSSES THE REGION. WEAK HIGH PRESSURE AND DRY WEATHER WILL DOMINATE THE WEATHER PATTERN REST OF THE LONG TERM. FIRST FOCUS IN LONGER TERM IS SHORTWAVE PRESSING INTO SCNTRL CANADA ON SUNDAY NIGHT AND SFC LOW/TROUGH MOVING ACROSS NORTHERN PLAINS. SLIGHT H85 TEMP/MOISTURE ADVECTION OVER UPR MICHIGAN AHEAD OF THE WAVE AND SFC TROUGH...BUT INSTABILITY IS PRETTY MINIMAL WITH MUCAPES 1-6KM A FEW HUNDRED J/KG AT BEST...MAINLY OVER FAR WEST LK SUPERIOR CLOSER TO STRONGEST H85-H7 MOISTURE TRANSPORT. FCST SOUNDINGS SHOW INCREASE OF H8-H7 MOISTURE BUT HINT AT DRY AIR BLO AND ABOVE THIS LAYER. WITH LACK OF INSTABILITY AND DEEP MOISTURE AND LARGER SCALE FORCING...THINK COVERAGE TO ANY SHRA/TSRA WILL BE LIMITED SUN NIGHT BUT CANNOT COMPLETELY RULE IT OUT. SEEMS THAT BETTER CHANCES FOR SHRA/TSRA OCCUR ON MONDAY IN THE MORNING DUE TO CLOSER PROXIMITY OF SHORTWAVE/H85 TROUGH AND RESULTING SHARPER WARM AIR ADVECTION AND INCREASING H85 MOISTURE TRANSPORT. EXPECT THIS WARM AIR ADVECTION SHRA/ISOLD TSRA TO SHIFT NORTH BY AFTN ALONG SFC WARM FRONT AND THEN...PROVIDED THERE IS ENOUGH CLEARING OF MORNING CLOUDS/SHRA/TSRA...THERE SHOULD BE PERIOD OF BUILDING INSTABILITY DURING PEAK HEATING AS TEMPS WARM INTO THE UPR 70S/LWR 80S. MLCAPES TOP OUT AROUND 800-1200J/KG...HIGHEST ALONG WI BORDER. DEEP LAYER SHEAR INCREASES IN WARM SECTOR OUT AHEAD OF COLD FRONT TO 30-40 KTS AS SHORTWAVE CROSSES NORTHERN ONTARIO AND ADJACENT LK SUPERIOR. SOUNDINGS SHOW A BIT OF CAPPING AROUND H8 AND THIS ADDS UNCERTAINTY TO INITIATION. BASED ON CAPE AND SHEAR BALANCE...THERE SEEMS TO BE AT LEAST SMALL POTENTIAL FOR ISOLD SVR STORMS. SUPERCELLS POSSIBLE AS WINDS SHOW SUFFICIENT VEERING WITH HEIGHT. HAIL/WIND PRIMARY HAZARDS WITH LOWER WBZERO HEIGHTS AROUND 11KFT AND DCAPE UP TO 1000J/KG. ALL THIS IS CONDITIONAL ON HOW MUCH INSTABILITY CAN MATERIALIZE. SINCE SPC DAY 3 DID INDICATE SEE TEXT OVER THE AREA...THINK IT IS WORTH AN HWO MENTION. COLD FRONT BLOWS THROUGH CWA PRETTY QUICKLY MONDAY EVENING/EARLY OVERNIGHT. TRENDED TOWARD LOWER POPS 6Z-12Z ON TUESDAY WITH DRYING NOTED IN SOUNDINGS AND GFS/ECMWF SHOWING LITTLE IF ANY QPF IN THAT TIME FRAME THE LAST FEW MODEL RUNS. IN WAKE OF THE COLD FRONT ON TUESDAY...COULD END UP WITH NEARLY CARBON COPY OF TODAY...COOL TEMPS ALONG LK SUPERIOR/HIGHER SWIM RISK AND READINGS INTO LOWER 70S TOWARD WI BORDER. CUT GUIDANCE TEMPS FOR TUESDAY NIGHT WITH HIGH CENTER OVERHEAD. FAVORED COLD SPOTS OVER MAINLY WEST COULD REACH TO AROUND 40 DEGREES. STAYS QUIET THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE SLOWLY RETREATS. NEXT CHANCE OF RAIN RETURNS THURSDAY INTO FRIDAY. MODELS HAVING TOUGH TIME HANDLING SHORTWAVE TROUGH PUSHING THROUGH IN WNW FLOW ALOFT. LATEST GFS AND ECMWF WOULD INDICATE SHORTWAVE PASSAGE THURSDAY OR THURSDAY NIGHT. BLEND OF CONSENSUS SHOWS SLIGHT CHANCE/LOW CHANCE POPS AS ANOTHER COLD FRONT CROSSES THE AREA TIED TO THE WAVE. SATURDAY LOOKING PRETTY COOL YET AGAIN BEHIND THIS COLD FRONT. PROBABLY WILL END UP SIMILAR TO WHAT IS OCCURRING TODAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 141 AM EDT SUN JUL 21 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD AS HIGH PRESSURE REMAINS OVER THE REGION. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 419 PM EDT SAT JUL 20 2013 AS HIGH PRESSURE BUILDS INTO THE NORTHERN GREAT LAKES...WINDS WILL DIMINISH THIS EVENING TO LESS THAN 20 KNOTS. SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA ON MONDAY. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20 TO 30 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND A COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...JLA AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
400 AM CDT SUN JUL 21 2013 .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 342 AM CDT SUN JUL 21 2013 EARLY THIS MORNING...A STALLED OUT AND WEAKLY-DEFINED SFC FRONTAL BOUNDARY EXISTED JUST N OF THE INTERSTATE 70 CORRIDOR. PCPN THAT HAD DEVELOPED EARLIER IN THE NIGHT IN THE AIRMASS NEAR IT OR TO THE S OF IT HAS SINCE DISSIPATED. A NEARLY STATIONARY MCS EXISTED NEAR THE INTERSECTION OF KS-MO-OK AND IF ANY MOVEMENT IS EXPECTED OF IT...IT SHOULD BE A SLOW ONE TO THE SE. FURTHER TO THE NW...A WEAKENING COMPLEX OF TSRA WAS OVER THE MID MO VALLEY IN ERN NEBRASKA MOVING E-SE WITH ANOTHER BATCH OF TSRA FURTHER TO THE W OVER THE HI PLAINS OF WRN SD AND WRN NEBRASKA. THIS SEWD MOVEMENT OF SYSTEMS IS COURTESY OF WEAK NW UPPER LEVEL FLOW THANKS TO THE UPPER LEVEL RIDGE RETREATING TO THE SWRN CONUS. TEMPS AROUND THE AREA ARE IN THE LO 70S FOR MOST AREAS...WITH 60S IN THE FAR NRN FA. THE MODELS TAKE THE FRONTAL BOUNDARY AND CONTINUE TO STALL IT IN ITS CURRENT POSITION JUST N OF THE INTERSTATE 70 CORRIDOR THIS MORNING...AND THEN RETREAT IT BACK TO THE N THIS AFTERNOON. IF THE AIRMASS IS ANYTHING LIKE THE PAST COUPLE OF DAYS...IT WILL BE EASIEST TO GENERATE TSRA ALG-S OF THE FRONT WHERE CINH WILL BE CLOSE TO NIL AND ENOUGH LOCALLY GENERATED LO LEVEL CONVERGENCE AND/OR SMALL UPPER LEVEL DISTURBANCES WILL PROVIDE ALL THE FOCUS NEEDED TO GET TSRA GOING. TIMING-WISE...LOOK FOR NEW DEVELOPMENT FROM MIDDAY ON WITH THE HEATING OF THE DAY AND REDUCTION OF CINH TO NEAR ZERO. THE MORE ORGANIZED SYSTEM TO OUR SW IS NOT EXPECTED TO GET HERE WHILE THE OTHER ORGANIZED SYSTEM TO OUR NW OVER NEBRASKA IS EXPECTED TO WEAKEN AS IT MOVES INTO MORE STABLE AIR BEHIND THE SFC FRONT ACROSS NE MO AND SE IA. HOWEVER...SOME MEASURE OF REORGANIZATION IS EXPECTED FROM THE REMNANT MCV OF THIS SYSTEM AS IT SLIDES THRU SRN IA TODAY BUT TIMING-WISE...PROBABLY WON/T HAVE MUCH OF A SAY IN THE FCST FOR OUR AREA UNTIL LATE IN THE DAY IN NE MO. AND SO...HAVE SLID POPS TODAY BACK TO HI-END CHC CATEGORY FROM LIKELYS EARLIER AS THIS UPPER LEVEL SYSTEM FROM THE NW IS EXPECTED TO AFFECT OUR AREA MORE SLOWLY THAN ORIGINALLY ANTICIPATED...WITH THE LIKELYS COMMUTED FOR MOST AREAS TO TONIGHT WHEN THE UPPER LEVEL SYSTEM MOVES THRU. VERY LITTLE CHANGE IN MAX TEMPS TODAY AND MIN TEMPS TONIGHT FROM PREVIOUS FCST...WITH MOST LOCATIONS REMAINING IN THE 80S TODAY WITH STL METRO AREA POSSIBLY REACHING 90F...AND MINS TONIGHT AROUND 70. TES .LONG TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 400 AM CDT SUN JUL 21 2013 NW UPPER LEVEL FLOW WILL PERSIST THRU THE PERIOD INTO NEXT WEEKEND. THIS WILL ENSURE THE EXTREME HEAT WILL REMAIN AT BAY...OR IF IT DOES INTRUDE IT WILL NOT LAST FOR LONG. AND UNTIL SFC FRONTAL BOUNDARIES CAN MAKE A DECENT PUSH THRU...THIS SETUP ALSO STRONGLY ALLUDES TO A CONTINUATION OF THE ACTIVE WX PATTERN THAT WE HAVE SEEN IN RECENT DAYS WITH A THREAT FOR TSRA. WE WILL EITHER BE IN A WARM SECTOR SETUP OR HAVE THE PRESENCE OF A FRONT OVER OUR AREA THRU TUESDAY NIGHT...AND THUS WILL HAVE THE LINGERING CHC FOR TSRA DURING THAT TIME. A CDFNT FINALLY LOOKS TO PUSH THRU BY WEDNESDAY THEN SHUNTING THE BETTER RAIN CHCS TO THE S AND SW AND PROVIDING A COUPLE OF MAINLY DRY DAYS WED AND THURS. MODELS CONTINUE TO ZERO IN ON WHAT COULD BE A SIGNIFICANT WIDESPREAD RAIN EVENT FOR LATE WEEK WITH APPROACH OF ANOTHER CDFNT AND WAVE OF LO PRES ALONG THIS FRONT THANKS TO A STRONG MID LEVEL SHORTWAVE TROF. TIMING RIGHT NOW LOOKS TO BE FROM LATE FRIDAY THRU EARLY SATURDAY AND HAS BEEN FAIRLY CONSISTENT RUN-TO-RUN THE PAST COUPLE OF DAYS. A BRIEF RETURN OF THE HEAT AND HUMIDITY IS ANTICIPATED FOR MUCH OF OUR AREA MONDAY AND TUESDAY AS THE FRONT RIDES TO THE N MONDAY THEN DROPS S AGAIN LATE TUESDAY. AMBIENT TEMPS IN THE 90-95 RANGE SHOULD YIELD HEAT INDEX VALUES AROUND 100 IN SPOTS...MAINLY STL METRO. IF THE FRONT DOES MAKE A GOOD PUSH THRU ON WEDNESDAY...TEMPS WILL STRUGGLE TO GET ABOVE 85 FOR THE REMAINDER OF THE PERIOD WITH A REINFORCING SHOT OF COOLER AIR DUE ON EITHER FRIDAY OR SATURDAY. TES && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1142 PM CDT SAT JUL 20 2013 LATEST CONVECTIVE TRENDS SHOW THAT CONVECTIVE CLUSTER EXTENDING FROM SOUTH OF JEFFERSON CITY IS DEVELOPING NORTHWEST TOWARDS SEDELIA MISSOURI AND WILL GRADUALLY MEET WITH DEVELOPING CONVECTION OVER NORTHWEST MISSOURI. THE LATEST HRRR MESOSCALE MODEL RUN SHOWS THE CONVECTIVE CLUSTER SOUTHWEST OF JEFFERSON CITY HOWEVER THE LATEST RUN DOES NOT SHOW THE DEVELOPING CONVECTION OVER NORTHWEST MISSOURI ATTM. THE AREA OF CONVECTION IS WTIHIN THE AXIS OF HIGHEST MLCAPE WHICH EXTENDS NORTHWEST - SOUTHEAST ACROSS NORTHWEST INTO SOUTH CENTRAL MISSOURI. CLUSTER OF THUNDERSTORMS FROM SOUTHEAST SOUTH DAKOTA THROUGH CENTRAL NEBRASKA ASSOCIATED WITH UPPER LEVEL DISTURBANCE OVER THE NORTHERN PLAINS. THIS DISTURBANCE WILL MOVE EAST-SOUTHEAST ALONG THE MEAN NORTHWEST FLOW AND BRING INCREASING THREAT TO SHOWERS AND THUNDERSTORMS OVER CENTRAL MISSOURI BY ;ATE MORNING TO MID DAY AND MOVE INTO EASTERN SECTIONS OF MISSOURI AND SOUTHWEST ILLINOIS BY NID TO LATE AFTERNOON. SPECIFICS FOR KSTL...WINDS WILL BE LIGHT AND VARIABLE THROUGH DAYBREAK ON SUNDAY. THEN WINDS WILL BECOME SOUTHEAST AT 5 TO 8 KTS. ISOLATED SHOWERS ANDT HUNDERSTORMS ARE POSSIBLE BY LATE MORNING FOR STL BUT HIGHER CHANCES INCREASE BY MID AFTERNOON. CEILING WILL REMAIN AOA 10000 FT BUT LOWER CEILNGS ARE EXPECTED BY EARLY TO MID AFTERNOON AS THUNDERSTORMS THREAT WILL INCREASE DURING THE MID TO LATE AFTERNOON HOURS OVER STL. GUSTING SURFACE WINDS UP TO 30 TO 35 KTS ARE POSSIBLE WITH THE STRONGER STORMS. PRZYBYLINSKI && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
342 AM CDT SUN JUL 21 2013 .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 342 AM CDT SUN JUL 21 2013 EARLY THIS MORNING...A STALLED OUT AND WEAKLY-DEFINED SFC FRONTAL BOUNDARY EXISTED JUST N OF THE INTERSTATE 70 CORRIDOR. PCPN THAT HAD DEVELOPED EARLIER IN THE NIGHT IN THE AIRMASS NEAR IT OR TO THE S OF IT HAS SINCE DISSIPATED. A NEARLY STATIONARY MCS EXISTED NEAR THE INTERSECTION OF KS-MO-OK AND IF ANY MOVEMENT IS EXPECTED OF IT...IT SHOULD BE A SLOW ONE TO THE SE. FURTHER TO THE NW...A WEAKENING COMPLEX OF TSRA WAS OVER THE MID MO VALLEY IN ERN NEBRASKA MOVING E-SE WITH ANOTHER BATCH OF TSRA FURTHER TO THE W OVER THE HI PLAINS OF WRN SD AND WRN NEBRASKA. THIS SEWD MOVEMENT OF SYSTEMS IS COURTESY OF WEAK NW UPPER LEVEL FLOW THANKS TO THE UPPER LEVEL RIDGE RETREATING TO THE SWRN CONUS. TEMPS AROUND THE AREA ARE IN THE LO 70S FOR MOST AREAS...WITH 60S IN THE FAR NRN FA. THE MODELS TAKE THE FRONTAL BOUNDARY AND CONTINUE TO STALL IT IN ITS CURRENT POSITION JUST N OF THE INTERSTATE 70 CORRIDOR THIS MORNING...AND THEN RETREAT IT BACK TO THE N THIS AFTERNOON. IF THE AIRMASS IS ANYTHING LIKE THE PAST COUPLE OF DAYS...IT WILL BE EASIEST TO GENERATE TSRA ALG-S OF THE FRONT WHERE CINH WILL BE CLOSE TO NIL AND ENOUGH LOCALLY GENERATED LO LEVEL CONVERGENCE AND/OR SMALL UPPER LEVEL DISTURBANCES WILL PROVIDE ALL THE FOCUS NEEDED TO GET TSRA GOING. TIMING-WISE...LOOK FOR NEW DEVELOPMENT FROM MIDDAY ON WITH THE HEATING OF THE DAY AND REDUCTION OF CINH TO NEAR ZERO. THE MORE ORGANIZED SYSTEM TO OUR SW IS NOT EXPECTED TO GET HERE WHILE THE OTHER ORGANIZED SYSTEM TO OUR NW OVER NEBRASKA IS EXPECTED TO WEAKEN AS IT MOVES INTO MORE STABLE AIR BEHIND THE SFC FRONT ACROSS NE MO AND SE IA. HOWEVER...SOME MEASURE OF REORGANIZATION IS EXPECTED FROM THE REMNANT MCV OF THIS SYSTEM AS IT SLIDES THRU SRN IA TODAY BUT TIMING-WISE...PROBABLY WON/T HAVE MUCH OF A SAY IN THE FCST FOR OUR AREA UNTIL LATE IN THE DAY IN NE MO. AND SO...HAVE SLID POPS TODAY BACK TO HI-END CHC CATEGORY FROM LIKELYS EARLIER AS THIS UPPER LEVEL SYSTEM FROM THE NW IS EXPECTED TO AFFECT OUR AREA MORE SLOWLY THAN ORIGINALLY ANTICIPATED...WITH THE LIKELYS COMMUTED FOR MOST AREAS TO TONIGHT WHEN THE UPPER LEVEL SYSTEM MOVES THRU. VERY LITTLE CHANGE IN MAX TEMPS TODAY AND MIN TEMPS TONIGHT FROM PREVIOUS FCST...WITH MOST LOCATIONS REMAINING IN THE 80S TODAY WITH STL METRO AREA POSSIBLY REACHING 90F...AND MINS TONIGHT AROUND 70. TES .LONG TERM...(SUNDAY THROUGH NEXT SATURDAY) ISSUED AT 252 PM CDT SAT JUL 20 2013 (SUNDAY THROUGH TUESDAY) FOCUS THRU THE PERIOD CONTINUES TO BE PRECIP CHANCES. MDLS ARE IN RELATIVELY GOOD AGREEMENT WITH RESPECT TO MASS FIELDS AND IN GENERAL...HAVE A GENERAL CONSENSUS ON HOW THINGS WILL PAN OUT THRU THIS PERIOD. THERE ARE SOME DIFFERENCES IN TIMING AS WELL AS WHAT FEATURES WILL PRODUCE PRECIP AND WHICH MAY NOT. OVERALL...HAVE TRENDED TWD A GFS/LOCAL WRF SOLN WHICH ARE IN BETTER AGREEMENT THAN THE OTHER OPERATIONAL GUIDANCE. NOT MUCH IN THE WAY OF CHANGES TO THE PREV FORECAST WRT POPS OR TEMPS. LOWERED POPS ACROSS NRN PORTIONS OF THE CWA ON MON. THE S/W IS NOW PROGD TO BE E OF THOSE AREAS BY MON MORNING...BUT WILL KEEP LOW POPS FOR UNCERTAINTY IN TIMING. (WEDNESDAY THROUGH SATURDAY) NOT MUCH IN THE WAY OF CHANGES FROM THE PREV FORECAST THRU THIS PERIOD. MDLS ARE IN GENERALLY GOOD AGREEMENT REGARDING MASS FIELDS. EXPECT THIS PERIOD TO OVERALL BE COOLER WITH PRECIP CHANCES CONTINUING THRU WED. THURS REMAINS DRY WITH THE SFC RIDGE SETTLED OVER THE AREA. HOWEVER...MDLS TIMING THE NEXT S/W AND ASSOCIATED PRECIP INTO THE AREA BY FRI AND REMAINING OVER PORTIONS OF THE CWA INTO SAT. KEPT POPS ON THE LOWER SIDE DUE TO UNCERTAINTY IN TIMING AND WILL INCREASE AS CONFIDENCE BUILDS AND TIME APPROACHES. TILLY && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1142 PM CDT SAT JUL 20 2013 LATEST CONVECTIVE TRENDS SHOW THAT CONVECTIVE CLUSTER EXTENDING FROM SOUTH OF JEFFERSON CITY IS DEVELOPING NORTHWEST TOWARDS SEDELIA MISSOURI AND WILL GRADUALLY MEET WITH DEVELOPING CONVECTION OVER NORTHWEST MISSOURI. THE LATEST HRRR MESOSCALE MODEL RUN SHOWS THE CONVECTIVE CLUSTER SOUTHWEST OF JEFFERSON CITY HOWEVER THE LATEST RUN DOES NOT SHOW THE DEVELOPING CONVECTION OVER NORTHWEST MISSOURI ATTM. THE AREA OF CONVECTION IS WTIHIN THE AXIS OF HIGHEST MLCAPE WHICH EXTENDS NORTHWEST - SOUTHEAST ACROSS NORTHWEST INTO SOUTH CENTRAL MISSOURI. CLUSTER OF THUNDERSTORMS FROM SOUTHEAST SOUTH DAKOTA THROUGH CENTRAL NEBRASKA ASSOCIATED WITH UPPER LEVEL DISTURBANCE OVER THE NORTHERN PLAINS. THIS DISTURBANCE WILL MOVE EAST-SOUTHEAST ALONG THE MEAN NORTHWEST FLOW AND BRING INCREASING THREAT TO SHOWERS AND THUNDERSTORMS OVER CENTRAL MISSOURI BY ;ATE MORNING TO MID DAY AND MOVE INTO EASTERN SECTIONS OF MISSOURI AND SOUTHWEST ILLINOIS BY NID TO LATE AFTERNOON. SPECIFICS FOR KSTL...WINDS WILL BE LIGHT AND VARIABLE THROUGH DAYBREAK ON SUNDAY. THEN WINDS WILL BECOME SOUTHEAST AT 5 TO 8 KTS. ISOLATED SHOWERS ANDT HUNDERSTORMS ARE POSSIBLE BY LATE MORNING FOR STL BUT HIGHER CHANCES INCREASE BY MID AFTERNOON. CEILING WILL REMAIN AOA 10000 FT BUT LOWER CEILNGS ARE EXPECTED BY EARLY TO MID AFTERNOON AS THUNDERSTORMS THREAT WILL INCREASE DURING THE MID TO LATE AFTERNOON HOURS OVER STL. GUSTING SURFACE WINDS UP TO 30 TO 35 KTS ARE POSSIBLE WITH THE STRONGER STORMS. PRZYBYLINSKI && .PRELIMINARY POINT TEMPS/POPS... SAINT LOUIS 88 73 93 75 / 50 60 40 40 QUINCY 86 70 90 72 / 50 60 20 30 COLUMBIA 85 70 92 72 / 60 60 30 50 JEFFERSON CITY 86 71 92 72 / 60 60 30 50 SALEM 87 72 88 71 / 50 50 40 30 FARMINGTON 85 70 91 72 / 50 50 50 50 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1202 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 937 PM CDT SAT JUL 20 2013 ISSUED AT 926 PM CDT SAT JUL 20 2013 DIURNAL CONVECTION AIDED BY A PLETHORA OF OUTFLOW BOUNDARIES AND A WEAK COLD FRONT HAS REALLY BECOME LIMITED TO JUST A FEW STORMS FROM THE LAKE OF THE OZARKS TO SULLIVAN MISSOURI. SHOULD SEE THIS CONVECTION CONTINUE TO SLOWLY DISSIPATE AS IT SQUEEZES OUT THE LAST OF THE SURFACE INSTABILITY. NEXT ROUND OF CONVECTION IS LIKELY TO DEVELOP FURTHER NORTHWEST...AS NORTHWEST MISSOURI REMAINS QUITE UNSTABLE WITH SPC MESOSCALE ANALYSIS SHOWING UPWARDS OF 4000 J/KG OF MUCAPE. APPROACHING SHORTWAVE FROM THE UPPER PLAINS SHOULD CAUSE THE LOW LEVEL JET TO INCREASE AND ACT UPON THIS INSTABILITY WITH THUNDERSTORMS INCREASING AFTER MIDNIGHT/SUNDAY MORNING. CVKING && .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 319 PM CDT SAT JUL 20 2013 THE WEST-EAST ORIENTED SURFACE COLD FRONT IS MEANDERING SOUTHWARD AND EXTENDED FROM JUST SOUTH OF KANSAS CITY TO JUST NORTH OF COLUMBIA AND ST LOUIS TO LITCHFIELD AT 20Z. SCATTERED THUNDERSTORMS HAVE DEVELOPED WITHIN THE LAST HOUR OR SO FROM JUST NORTH OF ST LOUIS INTO CENTRAL IL ALONG THE FRONT...BUT THE GREATEST COVERAGE OF STORMS IS ACROSS SOUTHEAST AND SOUTH CENTRAL MISSOURI ALONG AND AHEAD OF A WEAK SURFACE TROF/CONVERGENCE ZONE WHERE THE ATMOSPHERE IS VERY UNSTABLE. THESE SHOULD GENERALLY REMAIN THE FAVORED AREAS THRU SUNSET...AHEAD OF THE VERY SLOW MOVING FRONT AND CONVERGENCE ZONE. ALL OF THIS ACTIVITY WILL BE SLOW MOVING GIVEN WEAK FLOW AND SHEAR ALOFT BUT THE GENERAL TENDENCY SHOULD BE FOR AN OVERALL SEWD MOTION...ESPECIALLY WHERE MERGERS CAN LEAD TO GREATER ORGANIZATION. THE DECREASE IN INSTABILITY WITH SUNSET SHOULD RESULT IN LARGE DECREASE IN COVERAGE. THEN THE MAIN THREAT OF SHOWERS/STORMS FOR THE REMAINDER OF THE NIGHT WILL BE ALONG AND SOUTH OF THE FRONT WHICH WILL BECOME STATIONARY FROM SOUTHWEST ILLINOIS THRU MID MO INTO NRN KS. GLASS .LONG TERM...(SUNDAY THROUGH NEXT SATURDAY) ISSUED AT 252 PM CDT SAT JUL 20 2013 (SUNDAY THROUGH TUESDAY) FOCUS THRU THE PERIOD CONTINUES TO BE PRECIP CHANCES. MDLS ARE IN RELATIVELY GOOD AGREEMENT WITH RESPECT TO MASS FIELDS AND IN GENERAL...HAVE A GENERAL CONSENSUS ON HOW THINGS WILL PAN OUT THRU THIS PERIOD. THERE ARE SOME DIFFERENCES IN TIMING AS WELL AS WHAT FEATURES WILL PRODUCE PRECIP AND WHICH MAY NOT. OVERALL...HAVE TRENDED TWD A GFS/LOCAL WRF SOLN WHICH ARE IN BETTER AGREEMENT THAN THE OTHER OPERATIONAL GUIDANCE. NOT MUCH IN THE WAY OF CHANGES TO THE PREV FORECAST WRT POPS OR TEMPS. LOWERED POPS ACROSS NRN PORTIONS OF THE CWA ON MON. THE S/W IS NOW PROGD TO BE E OF THOSE AREAS BY MON MORNING...BUT WILL KEEP LOW POPS FOR UNCERTAINTY IN TIMING. (WEDNESDAY THROUGH SATURDAY) NOT MUCH IN THE WAY OF CHANGES FROM THE PREV FORECAST THRU THIS PERIOD. MDLS ARE IN GENERALLY GOOD AGREEMENT REGARDING MASS FIELDS. EXPECT THIS PERIOD TO OVERALL BE COOLER WITH PRECIP CHANCES CONTINUING THRU WED. THURS REMAINS DRY WITH THE SFC RIDGE SETTLED OVER THE AREA. HOWEVER...MDLS TIMING THE NEXT S/W AND ASSOCIATED PRECIP INTO THE AREA BY FRI AND REMAINING OVER PORTIONS OF THE CWA INTO SAT. KEPT POPS ON THE LOWER SIDE DUE TO UNCERTAINTY IN TIMING AND WILL INCREASE AS CONFIDENCE BUILDS AND TIME APPROACHES. TILLY && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1142 PM CDT SAT JUL 20 2013 LATEST CONVECTIVE TRENDS SHOW THAT CONVECTIVE CLUSTER EXTENDING FROM SOUTH OF JEFFERSON CITY IS DEVELOPING NORTHWEST TOWARDS SEDELIA MISSOURI AND WILL GRADUALLY MEET WITH DEVELOPING CONVECTION OVER NORTHWEST MISSOURI. THE LATEST HRRR MESOSCALE MODEL RUN SHOWS THE CONVECTIVE CLUSTER SOUTHWEST OF JEFFERSON CITY HOWEVER THE LATEST RUN DOES NOT SHOW THE DEVELOPING CONVECTION OVER NORTHWEST MISSOURI ATTM. THE AREA OF CONVECTION IS WTIHIN THE AXIS OF HIGHEST MLCAPE WHICH EXTENDS NORTHWEST - SOUTHEAST ACROSS NORTHWEST INTO SOUTH CENTRAL MISSOURI. CLUSTER OF THUNDERSTORMS FROM SOUTHEAST SOUTH DAKOTA THROUGH CENTRAL NEBRASKA ASSOCIATED WITH UPPER LEVEL DISTURBANCE OVER THE NORTHERN PLAINS. THIS DISTURBANCE WILL MOVE EAST-SOUTHEAST ALONG THE MEAN NORTHWEST FLOW AND BRING INCREASING THREAT TO SHOWERS AND THUNDERSTORMS OVER CENTRAL MISSOURI BY ;ATE MORNING TO MID DAY AND MOVE INTO EASTERN SECTIONS OF MISSOURI AND SOUTHWEST ILLINOIS BY NID TO LATE AFTERNOON. SPECIFICS FOR KSTL...WINDS WILL BE LIGHT AND VARIABLE THROUGH DAYBREAK ON SUNDAY. THEN WINDS WILL BECOME SOUTHEAST AT 5 TO 8 KTS. ISOLATED SHOWERS ANDT HUNDERSTORMS ARE POSSIBLE BY LATE MORNING FOR STL BUT HIGHER CHANCES INCREASE BY MID AFTERNOON. CEILING WILL REMAIN AOA 10000 FT BUT LOWER CEILNGS ARE EXPECTED BY EARLY TO MID AFTERNOON AS THUNDERSTORMS THREAT WILL INCREASE DURING THE MID TO LATE AFTERNOON HOURS OVER STL. GUSTING SURFACE WINDS UP TO 30 TO 35 KTS ARE POSSIBLE WITH THE STRONGER STORMS. PRZYBYLINSKI && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
301 AM CDT SUN JUL 21 2013 .DISCUSSION... FORECASTING AREAL EXTENT OF CONVECTION THROUGH THE FORECAST WILL BE A SIGNIFICANT CHALLENGE AS THE REGION REMAINS IN NORTHWEST FLOW THIS WEEK. FIRST ROUND OF CONVECTION IS MOVING INTO EASTERN NEBRASKA EARLY THIS MORNING...BUT WILL ALSO HAVE TO OVERCOME A POCKET OF DRY AIR AT H85. CONTINUED THETAE ADVECTION SHOULD HELP TO ERODE THIS DRY POCKET AND CONTINUE TRIGGER STORMS THIS MORNING THAT WILL CONTINUE TO MOVE EASTWARD THROUGH THE AREA INTO WESTERN IOWA BEFORE DISSIPATING THROUGH MID TO LATE MORNING. WHILE HEAVY RAINS ARE NOT WIDESPREAD...SOME VERY SPOTTY LOCATIONS WHERE LIGHTNING IS OCCURRING ARE LIKELY PICKING UP SOME DECENT MEANINGFUL RAINFALL. MEANWHILE...WATER VAPOR IMAGERY INDICATES ANOTHER SUBTLE WAVE IS LIKELY MOVING THROUGH WESTERN SOUTH DAKOTA. ANOTHER CLUSTER OF STORMS HAS REFIRED ACROSS THAT AREA...MOVING INTO NORTH CENTRAL NEBRASKA. BOTH THE NAM AND RAP SEEM TO HAVE PICKED UP ON THIS FEATURE AND MOVE IT THROUGH THE FORECAST AREA THIS AFTERNOON...WHICH COULD BE THE TRIGGER FOR ADDITIONAL STORMS AS WE HEAD THROUGH PEAK HEATING. FORWARD SPEED SUGGESTS THAT THIS MAY MOSTLY BE OUT OF THE AREA BY EARLY THIS EVENING. THE REMAINDER OF SUNDAY NIGHT AND MONDAY MORNING SHOULD BE DRY. A FRONTAL BOUNDARY MOVING INTO THE REGION COULD TRIGGER ISOLATED AFTERNOON STORMS IN NORTHEAST NEBRASKA. TEMPS AHEAD OF THE FRONT WILL PROBABLY REACH THE LOWER 90S ONCE AGAIN. SHOULD ALSO SEE A CHANCE OF THUNDERSTORMS MONDAY NIGHT AS THE FRONT MOVES THROUGH THE AREA. THE NEXT WAVE APPEARS ON THE HORIZON BY TUESDAY AFTERNOON THEN MOVES THROUGH THE REGION TUESDAY NIGHT. WEDNESDAY AND WEDNESDAY NIGHT SHOULD BE DRY...BUT ANOTHER WAVE MOVES INTO THE AREA ON THURSDAY AND LINGERS THROUGH FRIDAY. THE GFS SUGGESTS THAT WE MIGHT REMAIN DRY ON SATURDAY...BUT THE ECMWF HAS YET ANOTHER SURGE OF MOISTURE MOVING THROUGH. NEVERTHELESS...CONFIDENCE DECREASES IN SPECIFICS TOWARD THE END OF THE WEEK. DEWALD && .AVIATION...06Z TAFS FOR KOMA...KLNK...AND KOFK. FORECAST CONCERNS THROUGH THE PERIOD WILL BE CONVECTIVE CHANCES AND WHEN TO INCLUDE IN THE TAF. CONVECTION IS ONGOING ACROSS PARTS OF SOUTH DAKOTA AND WESTERN NEBRASKA AND IS ASSOCIATED WITH A SHORTWAVE TROF MOVING SOUTHEAST ACROSS THE DAKOTAS AND NEBRASKA THROUGH SUNDAY. THE LOW LEVEL JET WILL ALSO INCREASE OVER MISSOURI AND THE SHOULD AID IN NEW DEVELOPMENT FARTHER SOUTH AND WITH DEEPER MOISTURE RETURNING COULD SEE RE-DEVELOPMENT DURING THE DAY. SHOULD SEE SOME SHOWERS...HOWEVER DUE TO TSRA BEING ISOLD WILL ONLY MENTION SPARINGLY. COULD SEE SOME GUSTY WINDS NEAR SHOWERS/STORMS... OTHERWISE WINDS WILL GENERALLY BE FROM THE SOUTHEAST && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
113 AM CDT SUN JUL 21 2013 .SYNOPSIS... ISSUED AT 253 PM CDT SAT JUL 20 2013 THE H5 ANALYSIS THIS MORNING...HAS AN ACTIVE NW FLOW PATTERN ACROSS THE NRN CONUS. HIGH PRESSURE WAS ANCHORED ACROSS THE CENTRAL VALLEY OF CA...WITH A PERSISTENT BERMUDA HIGH PRESENT ACROSS THE WESTERN ATLANTIC. A BROAD TROUGH OF LOW PRESSURE EXTENDED FROM NRN QUEBEC INTO THE MID ATLANTIC STATES. ACROSS THE NRN ROCKIES AND CENTRAL PLAINS...NUMEROUS SHORTWAVES WERE EMBEDDED IN THE NWRLY FLOW. ONE OVER NWRN WYOMING...AND A SECOND OVER THE IDAHO PANHANDLE. ANOTHER DISTURBANCE WAS NOTED OVER NWRN IA AS WELL. AT THE SURFACE...SHOWERS AND THUNDERSTORMS HAVE CONTINUED ACROSS NORTHERN NEBRASKA THIS MORNING AND EARLY THIS AFTERNOON...ALONG A WEAK SURFACE BOUNDARY. TEMPERATURES AS OF 2 PM CDT RANGED FROM 68 IN RAIN COOLED AIR AT ONEILL...TO 87 AT OGALLALA...IMPERIAL AND NORTH PLATTE. && .UPDATE... ISSUED AT 111 AM CDT SUN JUL 21 2013 REDUCED CLOUD COVER WITH CLEARING SKIES SUBSIDENCE OVER WESTERN NEBRASKA. THUNDERSTORM CHANCES DROPPED INTO ISOLATED CATEGORIES AND QPF FIELDS DRASTICALLY REDUCED. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 SCATTERED THUNDERSTORMS THIS AFTERNOON ARE EXPECTED TO DEVELOP OVER THE NEBRASKA PANHANDLE AND NORTHWEST NEBRASKA AND COALESCE INTO A CONVECTIVE SYSTEM BY EARLY THIS EVENING. WITH THE DEEP SHEAR VECTORS DIAGONAL TO THE LOW LEVEL BOUNDARY...IT APPEARS TO FAVOR THE DEVELOPMENT OF A LINEAR CONVECTIVE SYSTEM. ACCORDING TO THE SHORT RANGE HRRR AND RAP13...THE SYSTEM WILL AFFECT A LARGE PART OF THE SANDHILLS AND SOUTHWEST NEBRASKA BY 01Z AND FINALLY CLEARING CENTRAL NEBRASKA BY 09Z. THEY DO INDICATE SOME LINGERING SHOWERS AND THUNDERSTORMS EVEN INTO EARLY SUNDAY. INSTABILITY CONTINUES OVER WESTERN NEBRASKA SUNDAY AND THERE IS A CHANCE OF ANOTHER CONVECTIVE SYSTEM DEVELOPING IN SOUTH DAKOTA AND NORTHWEST NEBRASKA LATE SUNDAY MORNING OR EARLY AFTERNOON...THEN CROSSING WESTERN NEBRASKA THROUGH THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 MID RANGE...SUNDAY NIGHT THROUGH TUESDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO TUESDAY...THANKS TO NWLY FLOW AND THE PRESENCE OF EMBEDDED SHORTWAVES WITHIN THAT FLOW. BEGINNING SUNDAY NIGHT...ANOTHER UPPER LEVEL DISTURBANCE WILL TRACK FROM THE CENTRAL AND NORTHERN ROCKIES...ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. CONVECTION WILL BE ONGOING BY SUNDAY AFTERNOON AND IS EXPECTED TO IMPACT MOST OF THE FORECAST AREA DURING THE EVENING AND OVERNIGHT HOURS. ATTM...WILL PAINT THE HIGHEST POPS IN THE CENTRAL AND SOUTHWESTERN CWA...AS THESE LOCATIONS WILL SEE THE BEST DEEP LAYER SHEAR OF 30 TO 40 KTS. SHEAR IN THE NERN ZONES WILL RUN 10 TO 20 KTS SUNDAY EVENING...SO ANY TSRAS IN THESE AREAS WILL BE FEW AND FAR BETWEEN. WILL CONTINUE MENTION OF THUNDERSTORMS IN THE FORECAST OVERNIGHT IN THE SOUTHWESTERN ZONES AS THERE ARE INDICATIONS OF THE DEVELOPMENT OF A LOW LEVEL JET...WHICH BECOMES FOCUSED ACROSS SWRN AND CENTRAL NEBRASKA OVERNIGHT SUNDAY NIGHT. CONVECTION ALONG WITH THE EXITING DISTURBANCE...WILL FORCE A FRONTAL BOUNDARY THROUGH THE FORECAST AREA ON MONDAY...STALLING THIS FEATURE ACROSS CENTRAL AND EASTERN NEBRASKA MONDAY EVENING. ONCE AGAIN...UPPER LEVEL ENERGY WILL ENTER THE CENTRAL PLAINS FROM THE ROCKIES LATE IN THE DAY MONDAY...LEADING TO THE DEVELOPMENT OF THUNDERSTORMS. THERE IS SOME DISAGREEMENT AS TO WHERE THE UPPER LEVEL ENERGY WILL TRACK DURING THIS PERIOD SO CONFIDENCE IN LOCATION OF POPS IS LACKING ATTM. DECIDED TO CONFINE POPS INVOF OF THE FRONTAL BOUNDARY...IE...EASTERN CWA FOR MONDAY NIGHT. ON TUESDAY...EASTERLY WINDS WILL BECOME SOUTHERLY BY AFTERNOON AS HIGH PRESSURE DRIFTS EAST INTO THE UPPER MIDWEST. THE FRONTAL BOUNDARY WILL WASH OUT WHILE NORTHWESTERLY FLOW ALOFT CONTINUES. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL TRACK ACROSS THE REGION TUESDAY AFTERNOON AND TUESDAY NIGHT AS ANOTHER UPPER LEVEL DISTURBANCE TRACKS FROM THE CENTRAL AND NORTHERN ROCKIES ONTO THE CENTRAL PLAINS. LONG RANGE...TUESDAY NIGHT THROUGH SATURDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO THE EXTENDED PERIODS WITH ABUNDANT LOW LEVEL MOISTURE AND PERSISTENT WESTERLY AND NORTHWESTERLY FLOW ALOFT. NUMEROUS SHORTWAVES WILL TRACK ACROSS THE CENTRAL ROCKIES ACROSS THE CENTRAL PLAINS THROUGH THE PERIOD...LEADING TO A GOOD CHANCE FOR PRECIPITATION DURING THE PERIOD. TEMPERATURES WILL BE SEASONAL WITH HIGHS IN THE 80S AND LOWS IN THE UPPER 50S AND LOWER 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 111 AM CDT SUN JUL 21 2013 THUNDERSTORMS OVER SOUTH CENTRAL SOUTH DAKOTA HAVE PUT TEMPO GROUP IN KVTN TAF EARLY THIS MORNING. WITH UNCERTAINTY IN FORECAST HAVE LEFT THUNDERSTORMS OUT OF TAF FOR SUNDAY AFTERNOON. VFR CONDITIONS OVER WESTERN NEBRASKA EARLY THIS MORNING WITH CLEARING SKIES BEHIND THUNDERSTORMS MOVING INTO CENTRAL NEBRASKA. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...POWER SYNOPSIS...CLB SHORT TERM...SPRINGER LONG TERM...CLB AVIATION...POWER
AREA FORECAST DISCUSSION
NWS HASTINGS NE
111 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 942 PM CDT SAT JUL 20 2013 AS WAS THE CASE DURING THE PRECEDING DAY SHIFT...CONFIDENCE IN THUNDERSTORM TRENDS/RAIN CHANCES THROUGH THE OVERNIGHT HOURS CONTINUES TO RUN AT LESS-THAN-IDEAL LEVELS. FOR AT LEAST A SHORT TIME LONGER...THE ENTIRE CWA CONTINUES IN A MULTI-HOUR LULL IN THE WAKE OF AFTERNOON CONVECTION THAT HAS SINCE EXITED WELL SOUTHEAST OF THE CWA. ALTHOUGH AREAS FROM THE TRI-CITIES AND WEST/NORTHWEST ESSENTIALLY MISSED OUT ON THE EARLIER ROUND...SEVERAL SMALL POCKETS ACROSS NORTH CENTRAL KS AND FAR SOUTHERN NEB RECEIVED A QUICK 1-4 INCH DRENCHING PER OUR LOCAL STORM REPORTS. LOOKING AHEAD...THE ONLY SHOW IN TOWN AT THE 9 PM HOUR IS A SMALL LINEAR COMPLEX OF STRONG TO MARGINALLY SEVERE STORMS TRACKING SOUTH- SOUTHEAST THROUGH THE WEST CENTRAL/NORTH CENTRAL NEB SANDHILLS...BUT GRADUALLY APPROACHING THE FRINGES OF THE CWA. FARTHER UPSTREAM...ADDITIONAL CLUSTERS OF STRONG-SEVERE STORMS HAVE TAKEN OFF IN SOUTHERN SD. ON THE LARGE SCALE ALOFT...SEASONABLY DECENT WEST-NORTHWEST FLOW WILL PERSIST THROUGH THE NIGHT MAINLY AT/ABOVE 500 MILLIBARS...WHILE FAIRLY CHAOTIC AND LIGHT FLOW PERSISTS A BIT LOWER AT 700MB...AND LOWER YET EVEN THE FLOW AT 850MB APPEARS QUITE UNDERWHELMING...WITH THE PRIMARY EXIT REGION OF A FAIRLY WEAK LOW LEVEL JET AIMED NORTH OF THE LOCAL AREA NEAR THE NEB/SD BORDER. AS A RESULT...GIVEN THE LACK OF NOTABLE THETA-E ADVECTION/CONVERGENCE IN AND NEAR THE CWA AT BOTH THE 850/700MB LEVEL...OUR CURRENTLY-ADVERTISED 50+ PERCENT POPS ACROSS THE MAJORITY OF THE CWA OVERNIGHT ARE COMING INCREASINGLY UNDER QUESTION ESPECIALLY IN THE CENTRAL/SOUTHEAST COUNTIES. NOT SURPRISINGLY...THE LATEST 00Z NAM AND HRRR ARE BOTH PRETTY PALTRY WITH MEASURABLE RAIN POTENTIAL OVERNIGHT. BASED ON CURRENT RADAR TRENDS...IT MAY VERY WELL END UP BEING THE CASE THAT THE BEST HOPE FOR LEGITIMATE RAINFALL WILL HINGE ON HOW SUCCESSFULLY THE ACTIVITY CURRENTLY DRIFTING TOWARD THE FAR NORTHWEST EDGES OF THE CWA HOLDS TOGETHER OVER THE NEXT FEW HOURS. PER THE LATEST RAP INSTABILITY TRENDS...THERE COULD BE AT LEAST A MODEST INCREASE IN ELEVATED MUCAPE IN THE 850-700MB LAYER INTO THE 500-1000 J/KG RANGE AS THE NIGHT WEARS ON...BUT MODEL SOUNDINGS SHOW THAT EVEN MUCH OF THIS INSTABILITY MAY BE RATHER CAPPED. AS FOR ANY OVERNIGHT SEVERE THREAT...THAT ALSO APPEARS TO BE ON A DECLINE...UNLESS SOMEHOW THE CONVECTION CURRENTLY IN THE NORTH PLATTE CWA RE-INTENSIFIES OR DEVELOPS A NEW VIGOROUS COLD POOL OVER THE NEXT FEW HOURS. HAIL-WISE...IT MAY BE TOUGH TO GET ANYTHING LARGER THAN DIMES-NICKELS GIVEN LATEST INSTABILITY TRENDS. IN SUMMARY...WILL CONTINUE TO EXAMINE THE LATEST TRENDS AND POTENTIALLY DECREASE POPS ACROSS PARTS OF THE CWA IN A FORTHCOMING EVENING UPDATE...BUT IN THE CONTINUED PRESENCE OF SUBTLE NORTHWEST-FLOW FORCING...PROBABLY CANNOT EXCLUDE ANY LOCATION FROM AT LEAST A TOKEN 20 PERCENT CHANCE OF SHOWERS/STORMS OVERNIGHT...AS NORTHWEST FLOW IS NOTORIOUS FOR PROVIDING A FEW SURPRISES. BY AND LARGE THOUGH...ITS STARTING TO LOOK LIKE THE 50+ POPS WE/VE BEEN ADVERTISING THE PAST FEW DAYS MAY PROVE OVERDONE FOR A DECENT CHUNK OF THE AREA...ESPECIALLY FOR THOSE LOOKING FOR MORE THAN A FEW TENTHS OF AN INCH. ALSO MAY BE MAKING A FEW DOWNWARD TWEAKS TO OVERNIGHT LOW TEMPS BASED ON LATEST OBSERVATIONAL TRENDS AND GUIDANCE. WILL BE DEFER TO ONCOMING OVERNIGHT SHIFT TO MAKE CHANGES BEYOND 12Z SUNDAY MORNING...BUT IT APPEARS IT COULD BE ANOTHER DAY/NIGHT OF FICKLE THUNDERSTORM TRENDS. LOOK FOR NEXT ROUND OF FORECAST UPDATES TO BE OUT BETWEEN 10-1030 PM... && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 353 PM CDT SAT JUL 20 2013 ALOFT: QUASI-ZONAL WNW FLOW WILL CONT THRU 00Z/MON. WV IMAGERY SHOWS A SUBTLE SHRTWV TROF MOVING INTO THE PANHANDLE FROM WY. THIS TROF IS FCST TO DEEPEN TNGT...CROSS THE FCST AREA SUN MRNG...AND WILL BE MOVING INTO NERN KS DURING PEAK HEATING. WHILE THIS TROF MAY AID TSTM DEVELOPMENT TNGT...HAVE TO WONDER IF SUBSIDENCE IN ITS WAKE WILL CAP OFF TSTM THREAT SUN AFTN. SFC: NUMEROUS OUTFLOW BOUNDARIES WILL LINGER THRU SUN. THE LEE/HEAT LOW WILL STRENGTHEN AND DRIFT INTO WRN KS. THIS SHOULD DROP DWPTS SUBSTANTIALLY FROM MCK-PHG-RCP AND PROBABLY DID NOT GO LOW ENOUGH. RAINFALL: PLEASE FOLLOW OUR LOCAL STORM REPORTS /LSR/. WE HAVE SEEN SOME SUBSTANTIAL 2-3 INCH AMTS BUT IT HAS BEEN FEAST OR FAMINE. REST OF THIS AFTN: THE ATMS HAS APPARENTLY STABILIZED OVER MUCH OF S-CNTRL NEB BASED ON THE LACK OF CU AND A WWD MOVING OUTFLOW BOUNDARY W OF HWY 283. SCT TSTMS WILL GRADUALLY DIE OFF OVER N-CNTRL KS. TNGT: PROBABLY SOMEWHAT OF A BREAK THIS EVNG. WE WERE WATCHING UPSTREAM TSTMS OVER THE PANHANDLE...WHICH THE MODELS SUGGESTED WOULD PROPAGATE INTO S-CNTRL NEB. THOSE TSTMS HAVE DIED WHICH LOWERS CONFIDENCE IN TNGT/S FCST...ESPECIALLY SINCE VIS SATPIX SHOW NO AGITATED CU FIELDS. SOME SEMBLANCE OF A COUPLED ULJ DEVELOPS TNGT...WHICH WILL ENHANCE THE LLJ. SO THE ENVIRONMENT WILL REMAIN FAVORABLE FOR ADDITIONAL TSTM DEVELOPMENT. SUN: IT ALL HINGES ON WHAT HAPPENS TNGT. IF SCT TSTMS FORM AND MOVE THRU THEN WE/LL SEE TSTMS DEPARTING DURING THE MRNG HRS WITH CLEARING THEREAFTER. FCST SOUNDINGS INDICATE DAYTIME HEATING SHOULD ERODE THE CAP. LEFTOVER OUTFLOW BOUNDARIES WILL PROVIDE FOCI FOR TSTM DEVELOPMENT. HOWEVER...IT APPEARS DOUBTFUL WE SEE ANYTHING MORE THAN AN ISOLATED TSTM MAYBE TWO? LARGE-SCALE SUBSIDENCE COULD LIMIT OR MITIGATE THE THREAT ALTOGETHER. IT/S POSSIBLE MODEL SOUNDINGS ARE NOT FULLY DEPICTING THIS. QPF IS PRETTY MEAGER SO IT MAY BE OF LITTLE CONSEQUENCE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 353 PM CDT SAT JUL 20 2013 GUIDANCE SUGGESTS NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER THE CENTRAL PLAINS THROUGH MUCH OF THE EXTENDED FORECAST PERIOD. THERE WILL BE THE POTENTIAL FOR MULTIPLE SMALL SCALE PERTURBATIONS TO WORK THEIR WAY ACROSS THE REGION AS A RESULT...WITH QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN SUGGESTING PRECIPITATION WILL BE REALIZED OVER VARIOUS PORTIONS OF OUR AREA DURING THE EXTENDED FORECAST PERIOD. AN EVEN AVERAGE OF THE NAM...OPERATIONAL GFS...EC...AND SREF-MEAN WAS UTILIZED TO DERIVE QPF FIELDS AND RESULTANT POPS FOR MONDAY AND TUESDAY...WHICH RESULTS IN LOW POPS BEING PRESENTED TO MOST ALL OF THE CWA BOTH DAYS. THE SAME PATTERN IS EXPECTED TO PERSIST THROUGH MUCH OF THE REST OF THE WEEK AS WELL...WITH ALLBLEND PROVIDING 20-60% POPS TO THE CWA AS A RESULT. THESE POPS WERE LEFT UNCHANGED FOR THE MOST PART. AS FOR SEVERE WEATHER CHANCES DURING THE EXTENDED FORECAST PERIOD...PERSISTENT LOW LEVEL MOISTURE SHOULD PRESENT DECENT CAPE VALUES ACROSS THE AREA...WITH GUIDANCE SUGGESTING SUCH VALUES WILL AVERAGE FROM 1500 TO 3000J/KG ON MOST DAYS. GIVEN THE UNCERTAINTY OF PLACEMENT AND TIMING OF SEVERE WEATHER HOWEVER...WILL PROVIDE A VAGUE SEVERE WEATHER MENTION IN THE HWO FOR MONDAY BUT LEAVE OUT ANY MENTION OF SEVERE WEATHER THROUGH THE REMAINDER OF THE EXTENDED FORECAST PERIOD. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT AFTERNOON HIGH TEMPERATURES IN THE 90S TO START THE EXTENDED FORECAST PERIOD...WITH SLIGHTLY COOLER AIR PROVIDING AFTERNOON HIGHS IN THE 80S TO NEAR 90 BY THE END OF THE EXTENDED FORECAST PERIOD. OVERNIGHT LOW TEMPERATURES IN THE 60S ARE EXPECTED FOR MOST PART DURING THE EXTENDED FORECAST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 102 AM CDT SUN JUL 21 2013 A LINE OF SHOWERS AND THUNDERSTORMS NORTH AND WEST OF GRAND ISLAND WILL SLIDE SOUTHEAST THROUGH KGRI OVER THE NEXT SEVERAL HOURS. THESE THUNDERSTORMS HAVE WEAKENED SOME OVER THE LAST HOUR AND ARE NON SEVERE. ODDS ARE GOOD THAT ANY PRECIPITATION WILL HAVE EXITED KGRI PRIOR TO DAWN. THE WIND WILL GENERALLY BE LIGHT AND VARIABLE TONIGHT...BUT COULD GUST TO AROUND 30 MPH IN AND AROUND THUNDERSTORMS. A SLIGHT CHANCE OF THUNDERSTORMS WILL CONTINUE INTO THE DAY ON SUNDAY...BUT THE CHANCE IS TOO LOW TO WARRANT INCLUSION IN THE TAF. THE PREDOMINATE WIND DIRECTION ON SUNDAY SHOULD BE SOUTHEAST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...PFANNKUCH SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...WESELY
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1133 PM CDT SAT JUL 20 2013 .SYNOPSIS... ISSUED AT 253 PM CDT SAT JUL 20 2013 THE H5 ANALYSIS THIS MORNING...HAS AN ACTIVE NW FLOW PATTERN ACROSS THE NRN CONUS. HIGH PRESSURE WAS ANCHORED ACROSS THE CENTRAL VALLEY OF CA...WITH A PERSISTENT BERMUDA HIGH PRESENT ACROSS THE WESTERN ATLANTIC. A BROAD TROUGH OF LOW PRESSURE EXTENDED FROM NRN QUEBEC INTO THE MID ATLANTIC STATES. ACROSS THE NRN ROCKIES AND CENTRAL PLAINS...NUMEROUS SHORTWAVES WERE EMBEDDED IN THE NWRLY FLOW. ONE OVER NWRN WYOMING...AND A SECOND OVER THE IDAHO PANHANDLE. ANOTHER DISTURBANCE WAS NOTED OVER NWRN IA AS WELL. AT THE SURFACE...SHOWERS AND THUNDERSTORMS HAVE CONTINUED ACROSS NORTHERN NEBRASKA THIS MORNING AND EARLY THIS AFTERNOON...ALONG A WEAK SURFACE BOUNDARY. TEMPERATURES AS OF 2 PM CDT RANGED FROM 68 IN RAIN COOLED AIR AT ONEILL...TO 87 AT OGALLALA...IMPERIAL AND NORTH PLATTE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 SCATTERED THUNDERSTORMS THIS AFTERNOON ARE EXPECTED TO DEVELOP OVER THE NEBRASKA PANHANDLE AND NORTHWEST NEBRASKA AND COALESCE INTO A CONVECTIVE SYSTEM BY EARLY THIS EVENING. WITH THE DEEP SHEAR VECTORS DIAGONAL TO THE LOW LEVEL BOUNDARY...IT APPEARS TO FAVOR THE DEVELOPMENT OF A LINEAR CONVECTIVE SYSTEM. ACCORDING TO THE SHORT RANGE HRRR AND RAP13...THE SYSTEM WILL AFFECT A LARGE PART OF THE SANDHILLS AND SOUTHWEST NEBRASKA BY 01Z AND FINALLY CLEARING CENTRAL NEBRASKA BY 09Z. THEY DO INDICATE SOME LINGERING SHOWERS AND THUNDERSTORMS EVEN INTO EARLY SUNDAY. INSTABILITY CONTINUES OVER WESTERN NEBRASKA SUNDAY AND THERE IS A CHANCE OF ANOTHER CONVECTIVE SYSTEM DEVELOPING IN SOUTH DAKOTA AND NORTHWEST NEBRASKA LATE SUNDAY MORNING OR EARLY AFTERNOON...THEN CROSSING WESTERN NEBRASKA THROUGH THE AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 253 PM CDT SAT JUL 20 2013 MID RANGE...SUNDAY NIGHT THROUGH TUESDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO TUESDAY...THANKS TO NWLY FLOW AND THE PRESENCE OF EMBEDDED SHORTWAVES WITHIN THAT FLOW. BEGINNING SUNDAY NIGHT...ANOTHER UPPER LEVEL DISTURBANCE WILL TRACK FROM THE CENTRAL AND NORTHERN ROCKIES...ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. CONVECTION WILL BE ONGOING BY SUNDAY AFTERNOON AND IS EXPECTED TO IMPACT MOST OF THE FORECAST AREA DURING THE EVENING AND OVERNIGHT HOURS. ATTM...WILL PAINT THE HIGHEST POPS IN THE CENTRAL AND SOUTHWESTERN CWA...AS THESE LOCATIONS WILL SEE THE BEST DEEP LAYER SHEAR OF 30 TO 40 KTS. SHEAR IN THE NERN ZONES WILL RUN 10 TO 20 KTS SUNDAY EVENING...SO ANY TSRAS IN THESE AREAS WILL BE FEW AND FAR BETWEEN. WILL CONTINUE MENTION OF THUNDERSTORMS IN THE FORECAST OVERNIGHT IN THE SOUTHWESTERN ZONES AS THERE ARE INDICATIONS OF THE DEVELOPMENT OF A LOW LEVEL JET...WHICH BECOMES FOCUSED ACROSS SWRN AND CENTRAL NEBRASKA OVERNIGHT SUNDAY NIGHT. CONVECTION ALONG WITH THE EXITING DISTURBANCE...WILL FORCE A FRONTAL BOUNDARY THROUGH THE FORECAST AREA ON MONDAY...STALLING THIS FEATURE ACROSS CENTRAL AND EASTERN NEBRASKA MONDAY EVENING. ONCE AGAIN...UPPER LEVEL ENERGY WILL ENTER THE CENTRAL PLAINS FROM THE ROCKIES LATE IN THE DAY MONDAY...LEADING TO THE DEVELOPMENT OF THUNDERSTORMS. THERE IS SOME DISAGREEMENT AS TO WHERE THE UPPER LEVEL ENERGY WILL TRACK DURING THIS PERIOD SO CONFIDENCE IN LOCATION OF POPS IS LACKING ATTM. DECIDED TO CONFINE POPS INVOF OF THE FRONTAL BOUNDARY...IE...EASTERN CWA FOR MONDAY NIGHT. ON TUESDAY...EASTERLY WINDS WILL BECOME SOUTHERLY BY AFTERNOON AS HIGH PRESSURE DRIFTS EAST INTO THE UPPER MIDWEST. THE FRONTAL BOUNDARY WILL WASH OUT WHILE NORTHWESTERLY FLOW ALOFT CONTINUES. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL TRACK ACROSS THE REGION TUESDAY AFTERNOON AND TUESDAY NIGHT AS ANOTHER UPPER LEVEL DISTURBANCE TRACKS FROM THE CENTRAL AND NORTHERN ROCKIES ONTO THE CENTRAL PLAINS. LONG RANGE...TUESDAY NIGHT THROUGH SATURDAY...A FAIRLY ACTIVE PATTERN WILL CONTINUE INTO THE EXTENDED PERIODS WITH ABUNDANT LOW LEVEL MOISTURE AND PERSISTENT WESTERLY AND NORTHWESTERLY FLOW ALOFT. NUMEROUS SHORTWAVES WILL TRACK ACROSS THE CENTRAL ROCKIES ACROSS THE CENTRAL PLAINS THROUGH THE PERIOD...LEADING TO A GOOD CHANCE FOR PRECIPITATION DURING THE PERIOD. TEMPERATURES WILL BE SEASONAL WITH HIGHS IN THE 80S AND LOWS IN THE UPPER 50S AND LOWER 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1129 PM CDT SAT JUL 20 2013 THE SCATTERED/NUMEROUS THUNDERSTORM ACTIVITY ACROSS SCNTL AND NCNTL NEB SHOULD EXIT THE FCST AREA AROUND 06Z. OTHER ISOLATED TSTM ACTIVITY ACROSS NRN NEB COULD CONTINUE OVERNIGHT. THE MODELS SUGGEST THIS ACTIVITY WILL MOVE EAST. OTHERWISE VFR IS EXPECTED THROUGH 20Z. THEREAFTER...SCATTERED TSTMS SHOULD REDEVELOP ACROSS WRN AND NCNTL NEB. STORM MOTION WILL BE EAST AND SOUTHEAST. THE RISK TO THE FCST IS THAT THE MODELS ARE TOO FAST SUNDAY. THUS ITS POSSIBLE THAT STORM DEVELOPMENT SUNDAY AFTN COULD HOLD OFF UNTIL 22Z-23Z. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...SPRINGER LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
351 AM EDT SUN JUL 21 2013 .SYNOPSIS... A TYPICAL SUMMER PATTERN OF HIGH PRESSURE OFFSHORE AND A TROUGH OF LOW PRESSURE INLAND WILL PERSIST THROUGH TUESDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST WEDNESDAY THEN STALL OVER THE REGION THURSDAY AND FRIDAY BEFORE MOVING OFFSHORE SATURDAY. && .NEAR TERM /TODAY/... AS OF 335 AM SUNDAY...A FEW PATCHY SHOWERS ARE AFFECTING THE CENTRAL PAMLICO SOUND AND CENTRAL OUTER BANKS REGION AND A COUPLE OF STRAY SHOWERS ARE MOVING OFF OF CORE BANKS EARLY THIS MORNING. THE 3 KM HRRR MODEL HAS HAD THE BEST DEPICTION OF THE PRECIPITATION PLACEMENT THIS MORNING AND WILL FOLLOW ITS TREND THROUGH THE MIDDAY HOURS. THERE WILL BE A LULL IN THE ACTIVITY THROUGH ABOUT MID-MORNING WHEN SOME ADDITIONAL SHOWERS MAY SCRAPE THE SOUTHERN COAST. MORE WIDESPREAD PRECIPITATION MOVES INTO THE SOUTHERN COASTAL PLAINS BY 18Z OR SO WITH HIGH CHANCE POPS OVER THE COASTAL PLAINS...TAPERING BACK TO CHC NEAR THE COAST. WITH PRECIPITABLE WATER VALUES BACK NEAR 2 INCHES...ANY SHOWERS THAT DEVELOP COULD PRODUCE A QUICK DOWNPOUR OF UP TO AN INCH OR SO. GIVEN MORE CLOUD COVER THAN RECENT DAYS...MAXIMUM TEMPERATURES SHOULD REMAIN IN THE UPPER 80S FAIRLY UNIFORM IN THE MIDDLE TO UPPER 80S AREA-WIDE. && .SHORT TERM /TONIGHT/... AS OF 345 AM SUNDAY...BOTH THE GFS AND NAM SHOW SOME STRONG MID- LEVEL VORTICITY RIDING UP THE COAST TONIGHT...COUPLED WITH A WEAK UPPER LEVEL TROUGH SLIDING ACROSS THE REGION. THIS ALONG WITH A VERY MOIST ATMOSPHERE WILL LEAD TO A CHANCE OF SHOWERS/TSTMS LINGERING THROUGH THE NIGHT. GIVEN THE TREND FROM THE LAST FEW NIGHTS...HAVE TRENDED THE BEST PRECIPITATION CHANCES NEAR THE COAST...WITH LITTLE ACTIVITY INLAND AFTER MIDNIGHT. OVERNIGHT LOWS TONIGHT SHOULD BE IN THE 73 TO 77 DEGREE RANGE. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 315 AM SUN...AN UPPER TROUGH OVER THE GREAT LAKES WILL DIG SOUTH MON/TUES AND PERSIST OVER THE EASTERN CONUS THROUGH THE LONG TERM...REINFORCING THE RAIN CHANCES THROUGH THE PERIOD. WEAK PERTURBATIONS IN THE MID AND UPPER LEVELS WILL ALSO AID IN DEVELOPING SHOWERS/TSTORMS DURING THE EXTENDED PERIOD...ESPECIALLY DURING PEAK HEATING HOURS OF THE DAY. AT THE SURFACE...LONG FETCH SW FLOW WILL TAP TROPICAL MOISTURE FROM THE GULF OF MEXICO AND WESTERN ATLANTIC MON AND TUES...INCREASING PWATS TO AROUND 2 INCHES. A WEAK COLD FRONT WILL APPROACH FROM THE NW MON INTO TUES...WHICH WILL DISSIPATE WEST OF THE REGION PRIOR TO ANOTHER COLD FRONT APPROACHING FROM THE NW WED INTO THURS. WITH DECENT MODEL AGREEMENT THROUGH THE EXTENDED...HAVE INDICATED A WEAK FRONTAL PASSAGE THURS NIGHT WITH BRIEF NORTHERLY FLOW/CAA ON FRI BEFORE OFFSHORE RIDGE KICKS IN A SW FLOW AGAIN TAKES OVER. HAVE CONTINUED THE TREND OF DIURNAL CONVECTION EACH DAY THROUGH THURS WITH 40 TO 50 PERCENT POPS INLAND DURING THE AFTERNOON AND 25-30 PERCENT POPS OVERNIGHT. TRIED TO ADJUST TIMING OF POPS MON AFTERNOON THROUGH TUES NIGHT TO ALSO COINCIDE WITH THE LOCATION OF SEVERAL SHORTWAVE VORTMAX ALOFT THAT ROTATE AROUND THE BASE OF THE BROAD UPPER TROUGH. SEVERE WEATHER IS NOT EXPECTED AS SHEAR WILL BE MINIMAL...THOUGH WITH ANY PULSE STORM AN ISOLATED STRONG TO SEVERE WIND GUST IS POSSIBLE. WITH OVERALL WEAK STEERING FLOW...ANY ORGANIZED CONVECTION WILL HAVE HEAVY RAINFALL POTENTIAL ESPECIALLY IF CELLS TRAIN OVER THE SAME AREA. POPS THURS NIGHT THROUGH FRI NIGHT REMAIN PINNED NEAR THE COAST WITH SCATTERED CONVECTION POSSIBLE AGAIN SAT AFTERNOON AS LIGHT SE/S FLOW RETURNS TO THE AREA. TEMPS THROUGH THE LONG TERM PERIOD WILL BE NEAR CLIMO WITH HIGHS IN THE UPPER 80S TO NEAR 90 WITH LOW/MID 70S FOR OVERNIGHT LOWS. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... SHORT TERM /THROUGH 00Z MONDAY/... AS OF 1250 AM SUN...SHOWERS HAVE MOVED EAST OF THE TAF SITES AND WITH A LIGHT SW BREEZE AND A 4 TO 6 DEGREE TEMPERATURE/DEWPOINT SPREAD...NO ISSUES WITH LOW CEILINGS OR VSBYS THUS FAR. THERE COULD BE SOME MVFR SCU CIGS PRIOR TO 12Z BUT THESE SHOULD BE SHORT-LIVED. SCT TSTMS DURING THE DAY ALONG AND INLAND OF SEA BREEZE. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 315 AM SUN...SCT THUNDERSHOWERS POSSIBLE EACH DAY FOR THE TERMINALS WITH MAINLY DRY CONDITIONS AT NIGHT AS PERSISTENT TROUGH OF LOW PRESSURE REMAINS OVER THE REGION. GENERALLY VFR EXCEPT FOR TEMPO RESTRICTIONS IN VSBY WITH THE SHOWERS/TSTORMS. COULD SEE BRIEF EARLY MORNING MVFR/IFR VSBYS DURING THE LONG TERM AS FORECAST SOUNDINGS INDICATE GOOD BOUNDARY LAYER MOISTURE TRAPPED UNDER A WEAK SURFACE BASED INVERSION...ESPECIALLY FOR AREAS THAT RECEIVE RAINFALL. && .MARINE... SHORT TERM /TODAY AND TONIGHT/... AS OF 350 AM SUNDAY...WILL CONTINUE SMALL CRAFT ADVISORY THROUGH 5 AM FOR THE PAMLICO SOUND AND FAR NORTHERN WATERS AND WILL MONITOR FOR THE NEED TO EXTEND IT INTO MID-MORNING. GUSTY SW WINDS PERSIST BETWEEN DEEPENING SURFACE TROUGH OVER THE PIEDMONT AND BERMUDA HIGH PRESSURE TO THE EAST. THESE SW WINDS CONTINUE TO GUST INTO THE MID 20S...BUT ANY 6 FOOT SEAS ARE ON THE OUTER PERIPHERY OF THE MARINE ZONES. WINDS AND SEAS SUBSIDE LATER TONIGHT BEFORE INCREASING AGAIN LATE MONDAY...THUS ANOTHER SCA WILL LIKELY NEED TO BE ISSUED ONCE CURRENT ADVISORIES EXPIRE. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 320 AM SUN...HIGH PRESSURE OFF THE SE COAST WITH A THERMAL TROUGH INLAND WILL BE THE DOMINANT PATTERN THROUGH MUCH OF THE LONG TERM. EXPECT A BREAK IN THE GUSTY SW WINDS MON BEFORE REINFORCING TROUGH/FRONT APPROACH TUES INTO LATE WEEK. MARGINAL SCA CONDITIONS ARE EXPECTED ONCE AGAIN FROM OREGON INLET SOUTH TUES THROUGH TUES NIGHT AS THE GRADIENT INCREASES A BIT. NO SIGNIFICANT CHANGES TO THE MEDIUM AND LONG TERM. WINDS SHOULD BECOME LIGHT LATE IN THE WEEK AS GRADIENT RELAXES WITH TROUGH AXIS OVER OR JUST EAST OF THE WATERS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR AMZ135-150. SMALL CRAFT ADVISORY UNTIL 1 AM EDT MONDAY FOR AMZ152-154-156- 158. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...DAG AVIATION...CTC/DAG MARINE...CTC/DAG
AREA FORECAST DISCUSSION...CORRECTED
NWS BISMARCK ND
1237 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 1221 AM CDT SUN JUL 21 2013 THE INHERITED FORECAST FOR THE REMAINDER OF TONIGHT IS ON TRACK AND BLENDED TO THE 05 UTC OBSERVED TRENDS. THE FOCUS IS ON THE SEVERE THUNDERSTORM THREAT FOR SUNDAY...WHICH NOW INCLUDES A GREATER PORTION OF THE AREA COMPARED TO THE DAY 2 OUTLOOK FOR SUNDAY. AREAS EAST OF HIGHWAY 85 HAVE THE GREATEST POTENTIAL FOR SEVERE CONVECTION SUNDAY AFTERNOON AND EVENING. SEE THE NEW SPC DAY 1 OUTLOOK FOR DETAILS. UPDATE ISSUED AT 834 PM CDT SAT JUL 20 2013 LATEST REGIONAL RADAR SHOWS AN AREA OF SEVERE THUNDERSTORMS IN EASTERN MONTANA MOVING SOUTHEAST WITH TIME. MONITORING FOR ANY OUTFLOWS...WITH CURRENT MOVEMENT INDICATING THAT THIS AREA COULD MOVE INTO OUR FAR SOUTHWESTERN COUNTIES OF GOLDEN VALLEY/SLOPE/BOWMAN IN THE NEXT COUPLE OF HOURS. OTHERWISE EXPECT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS OVERNIGHT...WITH INCREASING WARM AIR ADVECTION ASSOCIATED WITH A WARM FRONT OVER EASTERN MONTANA. STILL SOME ISOLATED CONVECTION IN NORTHWESTERN SOUTH DAKOTA BUT NOTHING SEVERE AT THIS TIME. MINOR CHANGES FROM PREVIOUS FORECAST. UPDATE ISSUED AT 559 PM CDT SAT JUL 20 2013 REGIONAL RADAR IMAGERY SHOWS A COUPLE OF AREAS TO WATCH THIS EVENING. FIRST IS IN OUR SOUTHWEST...WITH A SEVERE THUNDERSTORM WATCH BOX UP TO OUR SOUTHWEST BORDER FROM SOUTH DAKOTA. THUNDERSTORMS CONTINUE TO REMAIN SOUTH OF THE BORDER...BUT COULD DEVELOP A BIT FURTHER NORTH WITH AN AGITATED CUMULUS FIELD EVIDENT NEAR BAKER AND ALONG OUR FAR SOUTHWESTERN ZONES. THE OTHER AREA WAS SEEN OVER NORTHEASTERN MONTANA WITH SEVERE THUNDERSTORMS ROLLING OUT OF SOUTHERN SASKATCHEWAN AND INTO NORTHERN MONTANA. WILL CONTINUE TO MONITOR DEVELOPMENT OF THESE THUNDERSTORMS FURTHER EAST THIS EVENING AND OVERNIGHT...AS WHAT IS BEING INDICATED BY THE HRRR (HIGH RESOLUTION RAPID REFRESH MODEL)...AS WELL AS THE OTHER SHORT TERM MODELS. WARM AIR ADVECTION INCREASES OVERNIGHT AS NAM/GFS SOUNDINGS SHOW MODERATE VEERING WIND PROFILES FROM THE SFC TO 750MB. EXPECTING AN INCREASE IN THE AREAL COVERAGE OF SHOWERS/ELEVATED THUNDERSTORMS THROUGH EARLY SUNDAY MORNING...AS THEY CONTINUE TO DEVELOP ALONG A WARM FRONT IN EASTERN MONTANA. NAM/GFS SOUNDINGS SHOW DECENT INSTABILITY/CAPE ABOVE 750MB OVERNIGHT...WITH SHOWALTER INDICES SHOWING AN INCREASED POTENTIAL FOR ELEVATED THUNDERSTORMS WEST OF MINOT THROUGH 12Z SUNDAY. THUS WILL CONTINUE TO MENTION ISOLATED TO SCATTERED THUNDERSTORMS WEST...AND JUST INTO PORTIONS OF CENTRAL NORTH DAKOTA OVERNIGHT. WILL MONITOR FOR ANY SEVERE POTENTIAL DURING THE EVENING/OVERNIGHT. MOST OF WESTERN AND CENTRAL NORTH DAKOTA GET INTO THE WARM SECTOR BY LATE MORNING AND EARLY AFTERNOON SUNDAY...SETTING THE STAGE FOR SEVERE THUNDERSTORMS ALONG AND AHEAD OF AN ADVANCING COLD FRONT. SEE PREVIOUS DISCUSSION BELOW FOR MORE DETAILS. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 310 PM CDT SAT JUL 20 2013 MAIN CONCERNS THIS PERIOD WILL BE THUNDERSTORMS ASSOCIATED WITH A WARM FRONT EXTENDED ACROSS EASTERN MONTANA THAT IS FORECAST TO TRACK EAST ACROSS THE STATE LATE TONIGHT AND SUNDAY. SATELLITE LOOPS SHOW CLOUD COVER ACROSS WESTERN NORTH DAKOTA IN LOW LEVEL MOIST UP SLOPE FLOW. A BAND OF MID LEVEL SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING THROUGH SOUTH CENTRAL NORTH DAKOTA. THIS IS EXPECTED TO DIMINISH AS IT MOVES EAST. THE FOCUS FOR TONIGHT AND SUNDAY WILL BE THE WARM FRONT IN EASTERN MONTANA THIS WILL BE PROVIDE LIFT AND WITH A SHORT WAVE TROUGH SUPPORT THUNDERSTORMS ACROSS THE NORTHWEST...AND THEN THE NORTH CENTRAL ON SUNDAY. ADDED THE MENTION OF SEVERE WHERE SPC HAS DEFINED THE SLIGHT RISK SUNDAY AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 315 PM CDT SAT JUL 20 2013 THE RISK OF SEVERE WEATHER CONTINUES FROM SUNDAY AFTERNOON INTO THE NIGHT...MAINLY OVER THE CENTRAL AND EASTERN PARTS OF THE FORECAST AREA. LONG TERM MODELS ARE IN AGREEMENT THROUGH THE PERIOD ON THE BIG PICTURE...NAMELY THAT THE H5 RIDGE OFF THE SOUTHWEST COAST BUILDS EAST INTO THE DESERT SOUTHWEST AND EXPENDS NORTH INTO THE NORTHERN ROCKIES AND AMPLIFIES. THIS KEEPS A WEAK NORTHWEST FLOW OVER NORTH DAKOTA WITH CHANCES FOR THUNDERSTORMS COMING AS RIDGE RIDER SHORT WAVES CREST THE RIDGE AND PASS THROUGH EVERY OTHER DAY. THIS PATTERN IS ENHANCED AS AN H5 LOW CUTS OFF OVER ONTARIO AND SENDS A TROUGH AXIS THROUGH DURING THE THURSDAY-FRIDAY TIME FRAME. THAT...AS INDICATED IN THE PREVIOUS LONG TERM DISCUSSION...WILL BE THE GREATEST CHANCES FOR STORMS IN THE LONG TERM...AFTER SUNDAY NIGHT. BUT AGAIN...THERE ARE CHANCES ABOUT EVERY DAY AS TIMING OF THE WAVES WILL LIKELY CHANGE FROM FORECAST TO FORECAST. TEMPERATURES SHOULD BE FAIRLY STEADY IN THE PATTERN...AND NOT TOO FAR FROM NORMAL...GENERALLY IN THE MID 70S NORTHEAST TO MID 80S SOUTHWEST AND LOWS IN THE 50S TO LOWER 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1221 AM CDT SUN JUL 21 2013 THE MAIN AVIATION HAZARD WITH THE 06 UTC TAF CYCLE WILL BE A POSSIBLE ROUND OF SEVERE THUNDERSTORMS TO POTENTIALLY IMPACT KBIS...KMOT AND KJMS POST 21 UTC. OTHERWISE...MVFR STRATUS IS POSSIBLE ACROSS THE AREA TONIGHT WITH WEAK EASTERLY UPSLOPE FLOW WITH SOME STATUS ALREADY FORMING ON SATELLITE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...WAA LONG TERM...JPM AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1221 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 1221 AM CDT SUN JUL 21 2013 THE INHERITED FORECAST FOR THE REMAINDER OF TONIGHT IS ON TRACK AND BLENDED TO THE 05 UTC OBSERVED TRENDS. THE FOCUS IS ON THE SEVERE THUNDERSTORM THREAT FOR SUNDAY...WHICH NOW INCLUDES A GREATER PORTION OF THE AREA COMPARED TO THE DAY 2 OUTLOOK FOR SUNDAY. AREAS EAST OF HIGHWAY 85 HAVE THE GREATEST POTENTIAL FOR SEVERE CONVECTION SUNDAY AFTERNOON AND EVENING. SEE THE NEW SPC DAY 1 OUTLOOK FOR DETAILS. UPDATE ISSUED AT 834 PM CDT SAT JUL 20 2013 LATEST REGIONAL RADAR SHOWS AN AREA OF SEVERE THUNDERSTORMS IN EASTERN MONTANA MOVING SOUTHEAST WITH TIME. MONITORING FOR ANY OUTFLOWS...WITH CURRENT MOVEMENT INDICATING THAT THIS AREA COULD MOVE INTO OUR FAR SOUTHWESTERN COUNTIES OF GOLDEN VALLEY/SLOPE/BOWMAN IN THE NEXT COUPLE OF HOURS. OTHERWISE EXPECT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS OVERNIGHT...WITH INCREASING WARM AIR ADVECTION ASSOCIATED WITH A WARM FRONT OVER EASTERN MONTANA. STILL SOME ISOLATED CONVECTION IN NORTHWESTERN SOUTH DAKOTA BUT NOTHING SEVERE AT THIS TIME. MINOR CHANGES FROM PREVIOUS FORECAST. UPDATE ISSUED AT 559 PM CDT SAT JUL 20 2013 REGIONAL RADAR IMAGERY SHOWS A COUPLE OF AREAS TO WATCH THIS EVENING. FIRST IS IN OUR SOUTHWEST...WITH A SEVERE THUNDERSTORM WATCH BOX UP TO OUR SOUTHWEST BORDER FROM SOUTH DAKOTA. THUNDERSTORMS CONTINUE TO REMAIN SOUTH OF THE BORDER...BUT COULD DEVELOP A BIT FURTHER NORTH WITH AN AGITATED CUMULUS FIELD EVIDENT NEAR BAKER AND ALONG OUR FAR SOUTHWESTERN ZONES. THE OTHER AREA WAS SEEN OVER NORTHEASTERN MONTANA WITH SEVERE THUNDERSTORMS ROLLING OUT OF SOUTHERN SASKATCHEWAN AND INTO NORTHERN MONTANA. WILL CONTINUE TO MONITOR DEVELOPMENT OF THESE THUNDERSTORMS FURTHER EAST THIS EVENING AND OVERNIGHT...AS WHAT IS BEING INDICATED BY THE HRRR (HIGH RESOLUTION RAPID REFRESH MODEL)...AS WELL AS THE OTHER SHORT TERM MODELS. WARM AIR ADVECTION INCREASES OVERNIGHT AS NAM/GFS SOUNDINGS SHOW MODERATE VEERING WIND PROFILES FROM THE SFC TO 750MB. EXPECTING AN INCREASE IN THE AREAL COVERAGE OF SHOWERS/ELEVATED THUNDERSTORMS THROUGH EARLY SUNDAY MORNING...AS THEY CONTINUE TO DEVELOP ALONG A WARM FRONT IN EASTERN MONTANA. NAM/GFS SOUNDINGS SHOW DECENT INSTABILITY/CAPE ABOVE 750MB OVERNIGHT...WITH SHOWALTER INDICES SHOWING AN INCREASED POTENTIAL FOR ELEVATED THUNDERSTORMS WEST OF MINOT THROUGH 12Z SUNDAY. THUS WILL CONTINUE TO MENTION ISOLATED TO SCATTERED THUNDERSTORMS WEST...AND JUST INTO PORTIONS OF CENTRAL NORTH DAKOTA OVERNIGHT. WILL MONITOR FOR ANY SEVERE POTENTIAL DURING THE EVENING/OVERNIGHT. MOST OF WESTERN AND CENTRAL NORTH DAKOTA GET INTO THE WARM SECTOR BY LATE MORNING AND EARLY AFTERNOON SUNDAY...SETTING THE STAGE FOR SEVERE THUNDERSTORMS ALONG AND AHEAD OF AN ADVANCING COLD FRONT. SEE PREVIOUS DISCUSSION BELOW FOR MORE DETAILS. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 310 PM CDT SAT JUL 20 2013 MAIN CONCERNS THIS PERIOD WILL BE THUNDERSTORMS ASSOCIATED WITH A WARM FRONT EXTENDED ACROSS EASTERN MONTANA THAT IS FORECAST TO TRACK EAST ACROSS THE STATE LATE TONIGHT AND SUNDAY. SATELLITE LOOPS SHOW CLOUD COVER ACROSS WESTERN NORTH DAKOTA IN LOW LEVEL MOIST UP SLOPE FLOW. A BAND OF MID LEVEL SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING THROUGH SOUTH CENTRAL NORTH DAKOTA. THIS IS EXPECTED TO DIMINISH AS IT MOVES EAST. THE FOCUS FOR TONIGHT AND SUNDAY WILL BE THE WARM FRONT IN EASTERN MONTANA THIS WILL BE PROVIDE LIFT AND WITH A SHORT WAVE TROUGH SUPPORT THUNDERSTORMS ACROSS THE NORTHWEST...AND THEN THE NORTH CENTRAL ON SUNDAY. ADDED THE MENTION OF SEVERE WHERE SPC HAS DEFINED THE SLIGHT RISK SUNDAY AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 315 PM CDT SAT JUL 20 2013 THE RISK OF SEVERE WEATHER CONTINUES FROM SUNDAY AFTERNOON INTO THE NIGHT...MAINLY OVER THE CENTRAL AND EASTERN PARTS OF THE FORECAST AREA. LONG TERM MODELS ARE IN AGREEMENT THROUGH THE PERIOD ON THE BIG PICTURE...NAMELY THAT THE H5 RIDGE OFF THE SOUTHWEST COAST BUILDS EAST INTO THE DESERT SOUTHWEST AND EXPENDS NORTH INTO THE NORTHERN ROCKIES AND AMPLIFIES. THIS KEEPS A WEAK NORTHWEST FLOW OVER NORTH DAKOTA WITH CHANCES FOR THUNDERSTORMS COMING AS RIDGE RIDER SHORT WAVES CREST THE RIDGE AND PASS THROUGH EVERY OTHER DAY. THIS PATTERN IS ENHANCED AS AN H5 LOW CUTS OFF OVER ONTARIO AND SENDS A TROUGH AXIS THROUGH DURING THE THURSDAY-FRIDAY TIME FRAME. THAT...AS INDICATED IN THE PREVIOUS LONG TERM DISCUSSION...WILL BE THE GREATEST CHANCES FOR STORMS IN THE LONG TERM...AFTER SUNDAY NIGHT. BUT AGAIN...THERE ARE CHANCES ABOUT EVERY DAY AS TIMING OF THE WAVES WILL LIKELY CHANGE FROM FORECAST TO FORECAST. TEMPERATURES SHOULD BE FAIRLY STEADY IN THE PATTERN...AND NOT TOO FAR FROM NORMAL...GENERALLY IN THE MID 70S NORTHEAST TO MID 80S SOUTHWEST AND LOWS IN THE 50S TO LOWER 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1221 AM CDT SUN JUL 21 2013 THE MAIN AVIATION HAZARD WITH THE 06 UTC TAF CYCLE WILL BE A POSSIBLE ROUND OF SEVERE THUNDERSTORMS TO POTENTIALLY IMPACT KBIS...KMOT AND KJMS POST 21 UTC. OUTSIDE OF THIS THREAT...VFR CONDITIONS ARE EXPECTED. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...WAA LONG TERM...JPM AVIATION...AYD
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
156 AM EDT SUN JUL 21 2013 .SYNOPSIS... HIGH PRESSURE OVER THE SOUTHEAST WILL WEAKEN DURING THE REMAINDER OF THE WEEKEND AS A COLD FRONT MOVES SOUTHWARD FROM THE GREAT LAKES. THE FRONT WILL STALL NORTH OF THE AREA ON SUNDAY AND THEN DISSIPATE OR RETURN NORTHWARD INTO MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EAST ON TUESDAY AND LINGER THROUGH LATE WEEK. A SECOND WEAK COLD FRONT WILL ARRIVE FROM THE NORTHWEST ON THURSDAY AND SETTLE JUST SOUTHEAST OF THE REGION THROUGH FRIDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 200 AM...CONDITIONS REMAIN RATHER CALM ACROSS THE REGION AS EARLIER CONVECTION HAS CEASED. LOW CLOUDS CONTINUE TO PREVAIL ACROSS MOST LOCATIONS WITH PATCHY FOG REMAINING LIKELY THROUGH MORNING. ADJUSTED TEMPERATURES AND DEWPOINTS TO REFLECT LATEST OBSERVATIONS AND LEFT THE REMAINDER OF FORECAST AS IS. PREVIOUS DISCUSSION... 1015 PM UPDATE...THUNDERSTORMS PERSIST AT THIS HOUR IN THE VICINITY OF A REMNANT GUST FRONT EXTENDING ACROSS THE LOWER SC PIEDMONT AND SOUTH SIDE OF THE CHARLOTTE METRO. LATEST SPC MESOANALYSIS SHOWS NEARLY 2000 J OF SBCAPE STILL UNINHIBITED JUST SOUTH OF THIS BOUNDARY...AS WELL AS A THERMAL GRADIENT IN THE SAME AREA THAT IS LIKELY PROVIDING ENOUGH FORCING TO GET PARCELS GOING. LIGHT SLY FLOW ON THE S SIDE OF THE BDY WILL CONTINUE TO REINFORCE THE GRADIENT AND IT MAY TAKE SOME TIME FOR THE REMNANT INSTABILITY TO BE CONSUMED. LATEST HRRR SUPPORTS THIS CONCEPT AS WELL AS THE SCHC POP WHICH HAS BEEN MAINTAINED OVERNIGHT FOR MOST OF THE CWFA...AS IT FEATURES A COUPLE OF ISOLATED CELLS HERE AND THERE...ESPECIALLY NEAR THE BLUE RIDGE. ON A FINAL NOTE...PATCHY FOG ALREADY DEVELOPING AT SOME SITES...PRIMARILY SITES WHICH SAW HEAVY RAIN THIS AFTN. FOLLOWING THAT THINKING THE MAIN AREA OF CONCERN WOULD BE THE FOOTHILLS AND UPPER PIEDMONT. AT THIS TIME THE REPORTING SITES ARE TOO SCATTERED TO NEED A DENSE FOG ADVY...AND NAM SOUNDINGS ARE NOT SUPPORTIVE OF WIDESPREAD DENSE FOG ANYWAY. HOWEVER...IT BEARS MONITORING AND WILL INFORM INCOMING SHIFT OF THIS CONCERN. AT 230 PM EDT SATURDAY...AN UPPER LEVEL TROUGH WILL SLOWLY AMPLIFY OVER THE EASTERN USA TONIGHT AND SUNDAY. A SHORTWAVE WILL MOVE INTO THE BASE OF THIS TROUGH OVER THE TN RIVER VALLEY LATE SUNDAY. DEEP GULF MOISTURE WILL BE TRANSPORTED NORTH INTO OUR AREA BY A GENTLE SW LOW LEVEL FLOW ON THE WEST SIDE OF A BERMUDA HIGH...WHILE A COLD FRONT DROPS SOUTH INTO VA. WITH LOW LEVEL FLOW NEARLY PARALLEL THE TO THE BLUE RIDGE...UPSLOPE FLOW WILL BE LIMITED...THOUGH STILL PRESENT. WITH THE LOWE LEVELS STABILIZING LATE THIS EVENING... CONVECTIVE COVER SHOULD DIMINISH. MODEL SOUNDINGS SHOW CAPE SURPASSING 1000 J/KG AGAIN ON SUNDAY...AND CONVECTIVE TRENDS ARE EXPECTED TO MIMIC TODAY...WITH THE GREATEST COVERAGE IN THE MOUNTAINS...WITH ACTIVITY SPREADING EAST INTO THE FOOTHILLS AND PIEDMONT WITH TIME. SHEAR WILL REMAIN WEAK HOWEVER...LIMITING STORM ORGANIZATION. MINIMUM TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL TONIGHT IN A MOIST AIR MASS. MAXIMUM TEMPERATURES SUNDAY WILL BE SLIGHTLY BELOW NORMAL...WITH CLOUDS...MOISTURE A FALLING HEIGHTS ALOFT LIMITING WARMING. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... AT 230 PM SATURDAY... 500 MB HEIGHTS GRADUALLY LOWER OVER THE SOUTHEAST MONDAY AND TUESDAY BUT SURFACE PATTERN CHANGES WILL BE RATHER SUBTLE. DIURNAL CONVECTION WILL CONTINUE INTO THE FORECAST PERIOD BEGINNING 00Z MONDAY THEN GRADUALLY DIMINISH DURING THE NIGHT. MOIST AND MODERATELY UNSTABLE AIR MASS WILL CONTINUE OVER THE REGION AND GFS DEPICTS SHORT WAVE TROUGH APPROACHING CWA BY 12Z MONDAY... SO AT LEAST SLIGHT CHANCE POPS WILL CONTINUE WELL INTO THE NIGHT. DURING DAYTIME MONDAY... CWA REMAINS IN AIRMASS CONDUCIVE TO CONVECTIVE STORM DEVELOPMENT SO POPS WILL INCREASE WITH DAYTIME HEATING INTO CHANCE CATEGORY WITH LIKELY POPS OVER HIGHER TERRAIN. GFS HAS ANOTHER SHORT WAVE TROUGH DROPPING INTO LONG WAVE TROUGH POSITION EARLY TUESDAY... SO CHANCE POPS WILL CONTINUE THROUGH THE NIGHT AND INTO TUESDAY WHEN DIURNAL HEATING CYCLE ONCE AGAIN LEADS TO HIGHER PROBABILITIES DURING AFTERNOON. NO SIGNIFICANT TEMPERATURE CHANGES WILL OCCUR DURING MONDAY TUESDAY. HIGHS OUTSIDE THE MOUNTAINS WILL BE IN THE UPPER 80S AND LOWER 90S WHILE MOUNTAIN VALLEY TEMPERATURES WILL BE IN THE LOWER TO MIDDLE 80S. VERY WARM LOW TEMPERATURES IN THE 60S AND LOWER 70S ARE EXPECTED TO CONTINUE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 230 PM SATURDAY... FLOW PATTERN ACROSS U.S. DURING THE PERIOD WILL CONSIST OF RIDGE IN THE WEST AND TROUGH OVER THE EASTERN STATES. BOUNDARY LAYER WILL REMAIN WARM AND MOIST SO COOL TEMPERATURES ALOFT ON WEDNESDAY WILL SUPPORT LAPSE RATES SUFFICIENTLY STEEP TO PROMOTE CONVECTION WITH APPROACH AND PASSAGE EARLY THURSDAY OF COLD FRONT. THEREAFTER DETAILS BECOME DIFFICULT TO RESOLVE AS FRONT DRIFTS SLOWLY SOUTHEAST AND APPEARS IN CURRENT GUIDANCE TO BECOME NEARLY STATIONARY JUST AFTER CROSSING CWA. THUS... AIR MASS CHANGE WILL NOT BE SUFFICIENTLY SIGNIFICANT TO ELIMINATE POPS BUT NUMBERS WILL BE IN THE LOWER END OF THE CHANCE SPECTRUM AND WILL DISPLAY A DIURNAL TREND. NO SIGNIFICANT CHANGES IN TEMPERATURE EXPECTED. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AT KCLT...CONTINUED WITH MOSTLY PERSISTENCE FORECAST FROM LAST NIGHT. EXPECTING MVFR FOG CONDITIONS TO DEVELOP IN THE NEXT HOUR OR SO ACROSS THE NC PIEDMONT WITH CIGS LESS THAT 1K FT. OTHERWISE...MVFR CONDITIONS WILL PREVAIL THROUGH MID MORNING THEN FINALLY GIVE WAY TO LOW END VFR CIGS BY AROUND NOON. AT THAT TIME...INTRODUCED MVFR PROB30 IN THE TAF FOR POSSIBLE AFTERNOON CONVECTION. EXPECTING AS MUCH...IF NOT MORE COVERAGE ACROSS THE REGION TODAY AS THE ATMOSPHERE CONTINUES TO MOISTEN. AFTER SUNSET EXPECTING CIGS TO LIFT ACROSS THE PIEDMONT TO SOLID VFR LEVELS AND REMAIN THAT WAY THROUGH THE REMAINDER OF THE TAF CYCLE. EXPECTING WINDS DURING THE PERIOD TO REMAIN LIGHT AND SOUTHWESTERLY. ELSEWHERE...RESTRICTIONS WILL CONTINUE...IF NOT WORSEN ACROSS THE REGION IN THE NEXT FEW HOURS AS VERY MOIST BOUNDARY LAYER SETTLES. LIKELY A REPEAT OF LAST NIGHT WITH REGARDS TO MVFR/IFR CIGS AT MOST SITES. IN ADDITION...ADDED TEMPO GROUPS FOR VISB RESTRICTIVE FOG AT ALL SITES WITH KAVL DROPPING DOWN TO AN IFR VISB. OTHERWISE...MUCH OF THE SAME AS KCLT ABOVE AS FAR AS MID MORNING LOW END VFR CIGS OVERSPREADING MOST OF THE AREA. BEYOND THAT...ADDED PROB30 GROUPS AT ALL SITES FOR MVFR TSRA RESTRICTIONS DURING THE LATE MORNING/AFTERNOON HOURS. EXPECTING CONVECTION TO INITIATE ACROSS THE HIGH TERRAIN FIRST...THEN SPREAD EASTWARD THROUGH THE PIEDMONT. CONDITIONS WILL IMPROVE THIS EVENING AS DAYTIME HEATING IS LOST AFTER SUNSET...WHERE SOLID VFR CIGS WILL RETURN. WINDS THROUGH THE PERIOD WILL BE LIGHT AND SOUTHWESTERLY. OUTLOOK...MOIST SOUTHWESTERLY FLOW CONTINUES INTO THE EARLY WEEK. THIS WILL HELP DRIVE SHOWERS AND THUNDERSTORMS...MAINLY IN THE AFTERNOON AND EVENING...AND LIKELY CAUSE RESTRICTIVE CIGS/VSBYS EARLY EACH MORNING. CONFIDENCE TABLE... 06-12Z 12-18Z 18-24Z 00-06Z KCLT LOW 57% MED 79% HIGH 100% HIGH 100% KGSP MED 69% MED 77% HIGH 100% HIGH 100% KAVL MED 64% LOW 58% LOW 58% HIGH 100% KHKY MED 67% LOW 51% HIGH 85% MED 75% KGMU MED 71% LOW 59% HIGH 86% HIGH 100% KAND LOW 56% MED 77% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...CDG/JAT/WIMBERLEY SHORT TERM...LGL LONG TERM...LGL AVIATION...CDG
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1227 AM CDT SUN JUL 21 2013 .UPDATE... SEE UPDATED AVIATION DISCUSSION BELOW. && .PREVIOUS DISCUSSION... .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT SEVERAL WEAK SHORT WAVES EMBEDDED WITHIN THE NORTHWEST FLOW ALOFT WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS ACROSS THE REGION THIS EVENING THOUGH SUNDAY. WITH HI-RES MODELS STRUGGLING TO DEPICT THE AREAS OF CONVECTION...WITH MAINTAIN AT LEAST A LOW POP THROUGH 18Z SUNDAY. AS OF 19Z...A NARROW LINE OF SHOWERS ARE MOVING SE ACROSS HYDE/HAND COUNTY. THESE STORMS SHOULD CONTINUE TO DISSIPATE AS THEY EXIT THIS CWA. FARTHER WEST...A MORE PRONOUNCED SHORT WAVE HAS CAUSED CONVECTION A DEVELOP OVER THE BLACK HILLS. THIS AREA IS BASICALLY UNCAPPED WITH SB-CAPE VALUES AROUND 2000 J/KG. THESE STORMS SHOULD CONTINUE TO GROW AS SOUTH TO EASTERLY LOW LEVEL FLOW WILL FILTER MOISTURE INTO SW SOUTH DAKOTA. WOULD EXPECT THESE STORM WILL REMAIN JUST SOUTH OF THE CWA AS THE LAYER STORM MOTION OFF THE RUC SUGGEST A SE MOTION. THAT SAID...SEVERAL OUTFLOW BOUNDARIES FROM EARLIER CONVECTION COULD RESULT IN A NORTHWARD JOG. CHANCES FOR THUNDERSTORMS IN THE EASTERN CWA TONIGHT/SUNDAY IS A LITTLE UNCLEAR AT THIS TIME. HALF THE MODEL SUGGEST LLJ INDUCED THUNDERSTORMS MOVING ACROSS THE EASTERN DAKOTAS BY 12Z. OTHERS SUGGEST CONVECTION COULD BE SOUTH/EAST/OR NORTH OF THIS CWA. WITH VERY LOW CONFIDENCE...WILL BROAD BRUSH MOST OF THE CWA WITH LOW POPS FOR NOW ON SUNDAY. AN AREA OF LOW PRESSURE AND SURFACE COLD FRONT WILL MOVE ACROSS THE REGION ON SUNDAY NIGHT/MONDAY MORNING. WITH THE MAJORITY OF THE PCPN FALLING POST FRONTAL...SEVERE STORMS DO NOT APPEAR POSSIBLE. COOLER TEMPERATURES ARE EXPECTED ON MONDAY WITH HIGHS IN THE UPPER 70S..IN THE NE...TO AROUND 90 IN THE SOUTHWEST CWA. A BLEND OF CONSALL/ALLBLEND SHOWS HIGHS COULD BE SLIGHTLY COOLER THAN CURRENTLY ADVERTISED. .LONG TERM...TUESDAY THROUGH SATURDAY NORTHWEST FLOW ALOFT WILL DOMINATE THROUGH THE EXTENDED. MAIN FORECAST CHALLENGE WILL BE TIMING SHORTWAVE ACTIVITY. THE PATTERN WILL REMAIN VERY ACTIVE THROUGH THURSDAY WITH A SERIES OF SHORTWAVES. TIMING AND INTENSITY ARE VERY DIFFICULT TO DETERMINE AT THIS TIME RANGE SO CONFIDENCE IN POPS IN ANY GIVEN PERIOD IS LOW. THAT SAID TUESDAY NIGHT DOES SEEM TO HAVE MODEL AGREEMENT ON BEING DRY WHILE THURSDAY HAS BEEN CONSISTENTLY STORMY. STUCK CLOSE TO ALLBLEND POPS BECAUSE OF UNCERTAINTY. BY FRIDAY SFC HIGH PRESSURE BEGINS TO DROP OUT OF CANADA AND NOSE INTO EASTERN SD. THE START OF THE WEEKEND APPEARS DRY FOR NOW AS A RESULT. TEMPERATURES WILL BE MUCH COOLER THROUGH THE PERIOD WITH HIGHS RANGING FROM THE UPPER 70S IN THE EAST TO THE MID 80S IN THE SOUTHWEST. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED AT ALL TAF LOCATIONS THROUGH TONIGHT AND SUNDAY. A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE REGION TONIGHT AND SUNDAY AND MAY AFFECT THE TERMINALS AT OR IN THE VICINITY. WILL WATCH FOR POSSIBLE AMENDMENTS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...SD LONG TERM...WISE AVIATION...PARKIN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1147 PM CDT SAT JUL 20 2013 .DISCUSSION... SEE AVIATION DISCUSSION BELOW/ && .AVIATION... MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE FORECAST AREA THE NEXT 24 HOURS. SHOWERS EARLIER THIS EVENING HAVE DISSIPATED AS NIGHTTIME LAND SURFACE COOLING HAS STABILIZED THE AIR MASS AND IS HELPING PREVENT SHOWERS FROM DEVELOPING. A MODEST SURGE OF SOUTH AND SOUTHEAST WINDS FROM THE GULF OF MEXICO WILL ADVANCE INTO THE AREA LATE SUNDAY. SOUTH AND SOUTHEAST WINDS ARE EXPECTED TO INCREASE TO 10 TO 15 MPH WITH A FEW HIGHER GUSTS BY LATE AFTERNOON SUNDAY. THIS WIND AND MOISTURE SURGE MAY INITIATE ISOLATED TO POSSIBLY SCATTERED SHOWERS...SPECIALLY ACROSS AREAS SOUTH OF SAN ANGELO...INCLUDING CROCKETT...SUTTON... KIMBLE...MASON...MENARD AND SCHLEICHER COUNTIES. THE PRIMARY AVIATION HAZARD WILL BE THE POSSIBILITY OF LIGHTNING. && .PREV DISCUSSION... /ISSUED 953 PM CDT SAT JUL 20 2013/ UPDATE... DIURNALLY DRIVEN SHOWERS HAVE DISSIPATED ACROSS WEST CENTRAL TX BUT WE CONTINUE TO SEE ECHOES ROTATING TO THE NORTHWEST AROUND THE MID/UPPER LEVEL CYCLONE NEAR THE BIG BEND. POPS WERE REMOVED ACROSS MOST OF THE FORECAST AREA THROUGH THE REMAINDER OF THE OVERNIGHT PERIOD BUT I DID RETAIN A SLIGHT CHANCE OF SHOWERS IN THE SOUTH...MAINLY CROCKETT AND SUTTON COUNTIES DUE TO THE PROXIMITY OF THIS UPPER LOW. BOTH THE 3K TTU WRF AND HRRR DEPICT WEAK CONVECTION MOVING INTO THIS AREA AFTER MIDNIGHT. OTHERWISE...ONLY MINOR MODIFICATIONS WERE MADE TO THE INHERITED FORECAST. JOHNSON PREV DISCUSSION... /ISSUED 633 PM CDT SAT JUL 20 2013/ DISCUSSION... SEE AVIATION DISCUSSION BELOW/ AVIATION... CURRENTLY ISOLATED SHOWERS HAVE DEVELOPED ACROSS MASON...MCCULLOUGH...MENARD...COLEMAN...SHACKELFORD AND SUTTON COUNTIES. AN ISOLATED SHOWER WAS NOTED JUST NORTH OF SAN ANGELO. MOST OF THESE SHOWERS ARE EXPECTED TO DISSIPATE AFTER SUNSET. ON SUNDAY THERE IS POTENTIAL FOR ISOLATED SHOWERS TO REDEVELOP... CAUSED BY AFTERNOON HEATING THAT WILL CAUSE WARM AIR TO RISE THROUGH A WEAKLY CAPPED ATMOSPHERE THAT HAS MOIST AIR IN THE LOWEST 5K FEET. THE MOST LIKELY SHOWER AREAS WILL BE ACROSS MASON...KIMBLE... SUTTON...MENARD AND SAN SABA COUNTIES. HOWEVER...MOSTLY VFR CONDITIONS WILL PREVAIL THE NEXT 24 HOURS ACROSS THE FORECAST AREA. PREV DISCUSSION... /ISSUED 349 PM CDT SAT JUL 20 2013/ SHORT TERM... /TONIGHT AND SUNDAY/ ISOLATED BRIEF SHOWERS AND THUNDERSTORMS INTO SUNDAY... MOIST LOW LEVEL MOISTURE WILL CONTINUE WITH A WEAKLY OR UNCAPPED ATMOSPHERE INTO SUNDAY. MOST STORMS EXPECTED TO DEVELOP MID AND LATE AFTERNOON UNDER MAXIMUM HEATING...THEN DISSIPATE AFTER SUNSET. HOWEVER...A FEW STORMS MAY LAST LONGER OVER SOUTHERN SECTIONS ALONG THE I-10 CORRIDOR AT NIGHT WHERE THE THE UPPER RIDGE IS WEAKEST. BRIEF HEAVY RAIN IS POSSIBLE IN SLOW MOVING STORMS. LONG TERM... THERE IS A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN SECTIONS ON MONDAY WITH DRY AND WARMER WEATHER FOR THE REMAINDER OF NEXT WEEK. A WEAK UPPER LEVEL LOW WILL BE SITUATED NEAR THE BIG BEND SUNDAY EVENING AND WILL DRIFT SOUTHWEST INTO NORTHERN MEXICO BY TUESDAY AFTERNOON. WE WILL STILL SEE A DECENT AMOUNT OF LOW AND MID LEVEL MOISTURE AROUND...ESPECIALLY ACROSS SOUTHERN SECTIONS ON MONDAY. KEPT INHERITED LOW POPS INTACT MAINLY OVER THE NORTHWEST HILL COUNTRY AND NORTHERN EDWARDS PLATEAU MONDAY AND MONDAY EVENING WHERE WIDELY SCATTERED SHOWERS AND FEW THUNDERSTORMS WILL BE POSSIBLE. HIGHS ON MONDAY WILL BE MAINLY IN THE LOW TO MID 90S WITH A FEW READINGS IN THE UPPER 90S ACROSS THE NORTHERN BIG COUNTRY. AN UPPER LEVEL RIDGE WILL BUILD SOUTHEAST ACROSS THE SOUTHERN ROCKIES AND INTO CENTRAL TEXAS TUESDAY THROUGH THE END OF THE WEEK. THE ECMWF DOES SHUNT THE RIDGE BACK TO THE WEST FRIDAY INTO SATURDAY AS A SHORT WAVE DROPS SOUTHEAST FROM THE NORTHERN ROCKIES...WITH AN ASSOCIATED WEAK COLD FRONT ENTERING THE AREA. THE GFS MAINTAINS A STRONGER RIDGE WITH THE FRONT REMAINING NORTH OF THE AREA. KEPT A DRY FORECAST GOING FOR NOW GIVEN THESE MODEL DISCREPANCIES. HIGH TEMPERATURES WILL WARM FROM THE LOW TO MID 90S ON TUESDAY...TO THE MID AND UPPER 90S WEDNESDAY THROUGH SATURDAY. OVERNIGHT LOWS WILL MAINLY BE IN THE LOWER 70S THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 71 93 72 94 74 / 5 10 10 10 10 SAN ANGELO 70 93 72 94 74 / 10 20 10 20 10 JUNCTION 70 92 72 93 73 / 10 30 20 20 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99/99
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
300 AM CDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 300 AM CDT SUN JUL 21 2013 CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS LOOKED VERY SIMILAR TO THIS TIME YESTERDAY...CONSISTING OF NORTHWEST FLOW FROM BRITISH COLUMBIA INTO THE GREAT LAKES REGION...NUMEROUS SHORTWAVES RIDING THROUGH THE FLOW...AND TROUGHING OVER SOUTHEAST CANADA. MOST OF THE SHORTWAVES ARE WEAK EXCEPT FOR A MORE IMPRESSIVE ONE OVER CENTRAL ALBERTA. THE MAIN SHORTWAVE OF INTEREST IN THE SHORT TERM IS ORIGINATING OUT OF CONVECTION OVER SOUTHEAST SD AND EASTERN NEBRASKA. AIRMASS OVER THE FORECAST AREA VARIES GREATLY FROM SOUTH TO NORTH WITH I-94 BEING A GREAT DIVIDING LINE. TO THE NORTH...DRIER AIR CHARACTERIZED BY SURFACE DEWPOINTS IN THE 40S AND LOW 50S WAS PRESENT. FARTHER UP TO THE NORTH...THE 00Z INL SOUNDING REPORTED A PRECIPITABLE WATER VALUE OF 0.49 INCHES. NOW...SOUTH AND WEST OF I-94...DEWPOINTS ARE IN THE 60S. THE 00Z SOUNDINGS FROM MPX AND DVN HAD PRECIPITABLE WATER VALUES AROUND 1.15 INCHES. SEPARATING THESE TWO AIRMASSES IS A STATIONARY FRONTAL BOUNDARY. ISOLATED SHOWERS/STORMS HAVE BEEN POPPING UP ALONG/NORTH OF THE BOUNDARY ALL NIGHT. SYNOPTIC OVERVIEW... NORTHWEST FLOW CONTINUES THROUGH THE SHORT TERM PERIOD. THE CONVECTIVELY INDUCED SHORTWAVE TROUGH APPROACHING SIOUX CITY IA AT 08Z MODELS ARE STRUGGLING WITH GREATLY. MOST MODELS...INCLUDING HI RESOLUTION RUNS SUCH AS THE HRRR AND HIRES-ARW ARE TOO SLOW. EXTRAPOLATION HAS THE MCV CROSSING MUCH OF IOWA THIS MORNING. POTENTIAL THEN EXISTS FOR SOME VERY WEAK RIDGING IN ITS WAKE FOR THIS AFTERNOON AND TONIGHT...AHEAD OF THE CURRENT ALBERTA SHORTWAVE WHICH DIGS INTO NORTHERN MN AND WESTERN ONTARIO BY 12Z MONDAY. TODAY... DESPITE THIS PERIOD BEING THE BEGINNING OF THE FORECAST...THE UNCERTAINTY IS QUITE HIGH. MUCH OF THIS UNCERTAINTY STEMS FROM THE TOO SLOW HANDLING FROM ALL MODELS REGARDING THE MCV APPROACHING SIOUX CITY IA AS OF 08Z. GENERALLY FOLLOWED AN EXTRAPOLATION APPROACH COMBINED WITH A SOMEWHAT SPED UP 21.05Z HRRR FORECAST TO COME UP WITH THE FORECAST TODAY. THE PLAN IS THAT THE MCV SHOULD TRACK ACROSS DES MOINES AND DAVENPORT THIS MORNING...WITH THE FORECAST AREA ON THE NORTH SIDE. SHOWERS AND A FEW EMBEDDED THUNDERSTORMS APPEAR LIKELY...PRIMARILY WEST OF THE MISSISSIPPI RIVER DURING THE MORNING HOURS. CONCERNED THAT THE DIURNAL EFFECTS ON LOW LEVEL MOISTURE TRANSPORT MAY CAUSE THE SHOWERS TO WEAKEN SOME AS WE APPROACH MID-DAY...THUS THE HIGHER CHANCES TO THE WEST. DURING THE AFTERNOON...IT IS HARD TO SAY WHATS GOING TO OCCUR. WE COULD EASILY BE IN SUBSIDENCE IN THE WAKE OF THE MCV...PREVENTING MUCH IN THE WAY OF ADDITIONAL PRECIPITATION. ON THE OTHER HAND...THE AFTERNOON IS PEAK HEATING AND WITH HIGHER DEWPOINTS TODAY...WE SHOULD BE ABLE TO BUILD 500-1500 J/KG OF CAPE AS SUGGESTED BY THE RAP. ANY SHORTWAVE COMING THROUGH THE NORTHWEST FLOW THATS HARD TO DISCERN AT THIS TIME COULD KICK OFF SHOWERS AND STORMS. ADDITIONALLY WE SHOULD STILL HAVE THAT STATIONARY FRONTAL BOUNDARY IN THE FORECAST AREA TO PROVIDE WEAK LOW LEVEL CONVERGENCE. THEREFORE... HAVE MAINTAINED AT LEAST 40-50 PERCENT CHANCES FOR THE AFTERNOON. REGARDING TEMPERATURES...ASSUMING SOME SUN TODAY WHICH SHOULD OCCUR...925MB TEMPS IN THE 18-20C RANGE SUPPORTS HIGHS IN THE 70S TO NEAR 80. TONIGHT... ANY CONVECTION THAT OCCURS THIS AFTERNOON WILL LIKELY HAVE A STRONG DIURNAL COMPONENT TO IT. THEREFORE...HAVE PRECIPITATION CHANCES DIMINISHING THROUGH THE EVENING HOURS. HOWEVER...850MB MOISTURE TRANSPORT DOES INCREASE THROUGH THE NIGHT AHEAD OF THE STRONGER SHORTWAVE DROPPING INTO NORTHERN MN. CONVECTION WILL LIKELY FORM ON THE NOSE OF THIS MOISTURE TRANSPORT...WHICH IS FORECAST FROM NORTHERN MN INTO NORTHERN WI. KEPT SOME 20 PERCENT CHANCES OVERNIGHT BOTH OVER TAYLOR/CLARK COUNTIES FOR THE NOSE OF THIS MOISTURE TRANSPORT. ALSO KEPT THE 20 PERCENT CHANCES OVERNIGHT FOR THE EASTERN HALF OF THE FORECAST AREA...IN THE EVENT ANY DIURNAL CONVECTION CAN SURVIVE...THOUGH AS THE CHANCE STATES THE CONFIDENCE IS LOW. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 300 AM CDT SUN JUL 21 2013 SYNOPTIC OVERVIEW... 20.00Z ECMWF/GFS/CANADIAN ALL CONTINUE THE NORTHWEST FLOW PATTERN THROUGH THE ENTIRE LONG TERM PERIOD. WHAT LOOKED TO BE A POSSIBILITY OF RIDGING BUILDING TOWARDS THE AREA BRIEFLY THURSDAY INTO FRIDAY IS NOW COMPLETELY GONE. PART OF THE REASON WE STAY IN NORTHWEST FLOW IS THE DEVELOPMENT OF AN OMEGA BLOCK OVER WESTERN CANADA BETWEEN TUESDAY AND WEDNESDAY...WHICH DOES NOT SHOW ANY SIGNS OF BREAKING DOWN FOR AWHILE. ADDITIONALLY...THERE APPEARS TO BE SOME MODEL STRUGGLES HANDLING SHORTWAVE TROUGHING COMING DOWN THE EAST SIDE OF THE OMEGA BLOCK...WHICH PUTS MORE UNCERTAINTY FOR THE FORECAST THURSDAY AND BEYOND. ONE THING THAT IS STARTING TO BECOME A LITTLE MORE EVIDENT IS FOR DEEPER TROUGHING OVER THE GREAT LAKES REGION AT THE END OF NEXT WEEKEND. 500MB STANDARDIZED ANOMALIES FOR 12Z SUNDAY FROM THE ECMWF/GFS ARE 1.5-2 BELOW NORMAL. HAZARDS... THERE COULD BE SOME ISOLATED SEVERE WEATHER LATE MONDAY AFTERNOON INTO THE EVENING HOURS...ASSOCIATED WITH A COLD FRONT COMING THROUGH...BUT CONFIDENCE IS LOW AS DESCRIBED BELOW. MONDAY THROUGH TUESDAY NIGHT... MUCH OF THE FOCUS HERE IS ON THE MONDAY/MONDAY NIGHT PERIOD. SHORTWAVE TROUGH OVER NORTHERN MN AND WESTERN ONTARIO AT 12Z MONDAY MODELS ALL AGREE ON SLIDING IT ACROSS NORTHERN ONTARIO. AS THIS OCCURS...A COLD FRONT ASSOCIATED WITH IT APPROACHES THE FORECAST AREA. TIMING ON THIS FRONT VARIES GREATLY. AT 00Z TUESDAY...TIMING VARIES FROM THE 21.00Z HIRES-ARW HAVING IT WEST OF MINNEAPOLIS TO THE 21.00Z ECMWF/GFS OVER MINNEAPOLIS AND THE 21.00Z CANADIAN/NAM/UKMET WHICH ARE OVER LA CROSSE. TRENDS AT LEAST FROM THE ECMWF/GFS SUGGEST A SLOWER APPROACH MAY BE THE WAY TO GO. THERE STILL REMAINS UNCERTAINTY ON CONVECTIVE CHANCES WITH THIS FRONT... 1. A WARM SURGE OF AIR AT 800MB IS STILL INDICATED TO COME OVER THE FRONT TO PROVIDING POTENTIAL CAPPING 2. THE SHORTWAVE TROUGH SLIDING ACROSS NORTHERN ONTARIO COULD END UP PUTTING RIDGING OVER THE FRONT FOR THE AFTERNOON AS SUGGESTED BY THE 21.00Z HIRES-ARW. 3. LOW LEVEL CONVERGENCE ON THE FRONT REMAINS IN QUESTION. 4. NOW THE FRONT BEING SLOWER...NOT COMING ACROSS THE FORECAST AREA AT PEAK HEATING...COULD BE A NEGATIVE FOR PRECIP. TO ACCOUNT FOR THE SLOWER TREND HAVE LOWERED PRECIPITATION CHANCES SOME MONDAY AFTERNOON. LEFT THE 40-60 PERCENT CHANCES FOR MONDAY EVENING AS THAT IS STILL FAIRLY WELL AGREED UPON BY GUIDANCE...THEN CHANCES DIMINISHING AFTER MIDNIGHT WITH LOSS OF HEATING AND THE FRONT PROGRESSING THROUGH THE AREA. DRY WEATHER FOLLOWS IN THE WAKE OF THE FRONT FOR TUESDAY AND TUESDAY NIGHT WHILE HIGH PRESSURE BUILDS IN AT THE SURFACE. 925MB TEMPS CLIMBING TO 21-24C AHEAD OF THE FRONT ON MONDAY PLUS SUNSHINE WILL ALLOW HIGHS TO CLIMB INTO THE 80S. MAY EVEN SEE 90 IN A FEW SPOTS IF MORE SUN OCCURS. MONDAY LOOKS HUMID AS WELL AS NEAR 70 DEGREE DEWPOINTS ADVECT IN AT THE SURFACE. COOLER HIGHS ON THE WAY FOR TUESDAY AS 925MB TEMPS TUMBLE TO 17-20C. TUESDAY NIGHT LOWS HAVE POTENTIAL TO GET INTO THE 40S AT THE TYPICAL COLDER SPOTS...DUE TO LIGHT WINDS AND PRECIPITABLE WATER VALUES FALLING TO 0.5-0.75 INCHES. WEDNESDAY THROUGH SATURDAY NIGHT... 20.00Z ECMWF/GFS/CANADIAN ARE SUGGESTING NUMEROUS WEAK SHORTWAVES DROP SOUTHEAST ACROSS THE FORECAST AREA WEDNESDAY THROUGH THURSDAY IN THE NORTHWEST FLOW ALOFT. HARD TO SAY IF ANY OF THESE ARE GOING TO DO ANYTHING PRECIP WISE. 20.00Z CANADIAN AND 19.12Z ECMWF WANT TO BRING SOME SHOWERS ACROSS WEDNESDAY NIGHT AND THURSDAY...THOUGH THE 20.00Z ECMWF BACKED OFF. WOULD THINK A DRIER SCENARIO IS MORE LIKELY GIVEN THE DRY AIRMASS COMING IN TUESDAY NIGHT/WEDNESDAY WITH CANADIAN HIGH PRESSURE IN PLACE. NEVERTHELESS...DID HONOR A 20 PERCENT CHANCE MAINLY ON THURSDAY JUST IN CASE. CHANCES INCREASE A LITTLE FOR THURSDAY NIGHT AND FRIDAY WHERE IT APPEARS A COLD FRONT WILL CROSS THE AREA...ASSOCIATED WITH A POTENT UPPER TROUGH DROPPING OVER MANITOBA AND NORTHERN ONTARIO. SOME OF THIS UPPER TROUGH LOOKS TO SWING ACROSS THE FORECAST AREA FRIDAY NIGHT AND SATURDAY...THUS STILL NEED TO CONTINUE AT LEAST 20 PERCENT CHANCES. BEING IN THIS NORTHWEST FLOW PATTERN COMBINED WITH EVEN DEEPER TROUGHING FORMING OVER THE WEEKEND SUGGESTS BELOW NORMAL TEMPERATURES. BY 12Z SUNDAY...BOTH THE 20.00Z ECMWF AND GFS DEPICT 850MB TEMPS FALLING TO 6-9C...CHILLY RELATIVELY SPEAKING FOR THE END OF JULY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1030 PM CDT SAT JUL 20 2013 MUDDLED WEATHER PICTURE WITH AN UNSTABLE AIRMASS INTERACTING WITH VARIOUS MESOSCALE SFC BOUNDARIES AND A FEW PERTURBATIONS IN THE UPPER LEVEL FLOW. THERE WILL BE PERIODS OF SHRA/TS ACROSS THE REGION THROUGH SUNDAY NIGHT...BUT TRYING TO HIGHLIGHT WHEN THE TAF SITES WOULD BE IMPACTED IS PROBLEMATIC AT BEST. CONFIDENCE IS LOW IN REFINING THE PCPN FORECAST AND MIGHT HAVE TO WAIT UNTIL PCPN IS ACTUALLY DEVELOPING TO FINE TUNE THE TAFS. THE MOST WIDESPREAD PCPN SHOULD BE TIED WITH THE UPPER LEVEL SHORTWAVES. WILL CONTINUE TO PAINT WITH A BROAD BRUSH AS A RESULT. OVERALL...EXPECT VFR CONDITIONS TO DOMINATE...ALTHOUGH A BRIEF PERIOD OF MVFR COULD ARISE WITH ANY THUNDERSTORM. FOR MONDAY...A SFC FRONT IS EXPECTED TO DROP SOUTHWARD INTO THE AREA. WITH UNSTABLE AIR TO WORK WITH...BELIEVE A LINE OF CONVECTION WILL DEVELOP IN RESPONSE...AND THERE COULD BE SOME STRONGER STORMS IN THE AFTERNOON/EARLY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
540 AM MST SUN JUL 21 2013 .UPDATE...UPDATED AVIATION DISCUSSION. && .SYNOPSIS... A LOW PRESSURE SYSTEM IN MEXICO WILL CONTINUE TO SUPPLY MOISTURE TO THE DESERT SOUTHWEST TODAY. HUMID CONDITIONS WILL RESULT IN WELL-ABOVE NORMAL RAIN CHANCES AND WELL-BELOW NORMAL TEMPERATURES. A DRYING TREND WILL BEGIN MONDAY...CONTINUING INTO WEDNESDAY AS HIGH PRESSURE BUILDS BACK OVER THE REGION. MONSOON MOISTURE MOVING BACK NORTHWARD INTO THE REGION IS LIKELY TO ONCE AGAIN INCREASE RAIN CHANCES FOR THE END OF THE WEEK AND INTO THE WEEKEND. && .DISCUSSION... UPPER LOW CONTINUES TO SPIN WESTWARD INTO THE PACIFIC OCEAN JUST OFF THE BAJA PENINSULA. FURTHER NORTH...THE MID-TROPOSPHERIC ANTICYCLONE REMAINS POSITIONED ACROSS CA/NV. RESULTING MID-LEVEL EASTERLY FLOW IS STRONGER THAN NORMAL (STANDARDIZED ANOMALY NEAR 1.0) AND CONTINUES TO ADVECT DEEP SUB-TROPICAL MOISTURE INTO THE FORECAST AREA. SURFACE DEWPOINTS ARE CURRENTLY IN THE LOWER 70S ACROSS THE PHOENIX METRO AREA WHILE THE GPS-IPW REGISTERED AROUND 1.75 INCHES...WELL ABOVE NORMAL. LATEST RAP INDICATES THAT PWATS MAY BE AS HIGH AS 2.0 TO 2.4 INCHES ACROSS THE SOUTHWEST DESERTS AND TOWARDS PUERTO PENASCO. LATEST WV IMAGERY SHOWS TWO MCS...ONE ACROSS THE MOJAVE DESERT AND THE OTHER ACROSS SOUTHERN AZ...BEARING DOWN ON SW AZ AND SE CA. STRONG LOW-LEVEL CONVERGENCE IS EXPECTED EARLY THIS MORNING AND POPS WERE INCREASED IN THESE AREAS. ACROSS SOUTH-CENTRAL AZ...NMM AND WRF-BASED GUIDANCE CONTINUES TO SUGGEST THAT SHOWERS WILL REDEVELOP AS EARLY AS THIS MORNING. THIS SEEMS REASONABLE GIVEN THE AMPLE MOISTURE AND IT WILL ONLY TAKE A MINIMAL AMOUNT OF HEATING FOR CONVECTION TO INITIATE. MODELS ALSO SUGGEST THAT VORTICITY-FORCED ASCENT WILL AID IN THE DEVELOPMENT OF STORMS THIS AFTERNOON ACROSS SE CA. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN AND LOCALIZED FLOODING. THE COPIOUS AMOUNT OF MOISTURE WILL ALSO RESULT IN CONSIDERABLE CLOUDINESS ACROSS MUCH OF THE AREA...WHICH WILL KEEP TEMPERATURES WELL BELOW NORMAL. FORECAST HIGH FOR PHOENIX IS 95 DEGREES. A MAX TEMP THIS LOW HAS NOT OCCURRED SINCE MAY 27. A SIGNIFICANT DRYING TREND WILL TAKE PLACE MONDAY AS THE UPPER LOW LIFTS STEADILY NORTHWARD. SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...THOUGH COVERAGE WILL BE NOTICEABLY LESS THAN WHAT HAS OCCURRED THE PAST FEW DAYS. THE UPPER LOW WILL BE PICKED UP BY THE WESTERLIES TUESDAY AS THE MONSOON HIGH BECOMES REPOSITIONED ACROSS THE ROCKIES. GFS/ECMWF DIFFER ON THE AMOUNT OF MOISTURE LEFT OVER ACROSS THE DESERT SOUTHWEST THOUGH THE CONSENSUS IS THAT IT SHOULD BE SUFFICIENT FOR ISOLATED THUNDERSTORMS THROUGH THE WEEK. FLOW WILL BE WEAK AS AN ANTICYCLONE BUILDS BACK ACROSS AZ AND CONVECTION WILL MAINLY BE RELEGATED TO THE HIGHER TERRAIN. A WARMING TREND IS ALSO EXPECTED WITH A RETURN TO ABOVE NORMAL TEMPERATURES BY THURSDAY. MODELS ARE IN GENERALLY GOOD AGREEMENT THAT ANOTHER PVD WILL SLIDE WESTWARD THROUGH SONORA LATE IN THE WEEK...RESULTING IN AN INFLUX OF MOISTURE. FORECAST IS FOR BELOW CLIMO POPS THROUGH MIDWEEK...FOLLOWED BY NEAR CLIMO POPS THURSDAY THROUGH SUNDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... NEW STORMS WILL CONTINUE TO DEVELOP TO THE SOUTH AND WEST OF THE PHOENIX AREA...WITH ACTIVITY SLOWLY BUILDING AROUND AND ENCROACHING ON THE TERMINALS LATER THIS MORNING AFTER 15Z...PERSISTING INTO THE AFTERNOON/EARLY EVENING. GENERALLY LIGHT WINDS AND SCT-BKN CLOUD DECKS AOA 6-8KFT ARE EXPECTED WITH PERIODS OF CIGS LOWERING TO 3-4KFT/VISIBILITIES REDUCED DOWN TO 4SM IN HEAVIER SHOWERS AND THUNDERSTORMS. STORMS DIMINISH AND SKIES EXPECTED TO IMPROVE AFTER 02Z MONDAY WITH SCT-BKN CLOUD DECKS SETTLING IN AOA 10KFT. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... ISOLATED SHOWER/THUNDERSTORM ACTIVITY WILL CONTINUE TO FILL IN OVER SOUTHEAST CALIFORNIA THIS MORNING THROUGH AT LEAST 17Z...WITH GUSTY OUTFLOWS TO 30KT POSSIBLE AT TIMES...ESPECIALLY NEAR KNYL. SCT-BKN CLOUD DECKS WITH CIGS DOWN TO AROUND 6-8KFT IN HEAVIER SHOWERS AND THUNDERSTORMS WITH SKIES/CIGS IMPROVING LATER THIS AFTERNOON. WINDS S-SELY AROUND 10-15KT THROUGH MUCH OF THE TAF PERIOD ACROSS THE LOWER COLORADO RIVER VALLEY/KBLH WITH LIGHTER SELY WINDS AT KIPL. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... A SWITCH TO A SOUTHERLY FLOW ALOFT WILL BRING DRYING CONDITIONS AND ENDING PRECIPITATION CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. SLIGHT CHANCES FOR STORMS WILL CONTINUE ACROSS SOUTH-CENTRAL ARIZONA WITH BETTER CHANCES ACROSS HIGHER TERRAIN LOCATIONS NORTH AND EAST OF PHOENIX. HUMIDITIES WILL REMAIN ELEVATED THROUGH THE ENTIRE PERIOD WITH AFTERNOON HUMIDITIES ONLY DROPPING INTO THE 20-30 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH AVIATION...MEYERS FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS MIAMI FL
956 AM EDT SUN JUL 21 2013 .UPDATE... LATEST ANALYSIS SHOWS A LARGE DEEP LAYER RIDGE CENTERED ACROSS SOUTH CENTRAL FLORIDA NEAR LAKE OKEECHOBEE. WITHIN THIS BOUNDARY, A WEAKNESS EXISTS AS A WEAK MID LEVEL TROUGH IS LOCATED JUST EAST OF THE MELBOURNE COAST. STREAMLINE ANALYSIS INDICATES STRONG UPPER LEVEL DIFFLUENCE IS OCCURRING WHICH IS THE REAL CULPRIT IN GENERATING STRONG CONVECTION ALONG THIS BOUNDARY. ORIGINAL THINKING WAS THAT MOST AFTERNOON DEVELOPMENT WOULD BE OVER THE INTERIOR PORTIONS OF SOUTH FLORIDA BENEATH THE RIDGE AND VERY LITTLE STORM MOTION. THE TRICKY PART OF THE FORECAST FOR THIS AFTERNOON IS GOING TO BE WHAT INFLUENCE THE TROUGH AND DIFFLUENCE MIGHT HAVE ON THE CONVECTION. THERE IS ALSO ABUNDANT CLOUD COVER THAT COULD LIMIT THE AMOUNT OF DIURNAL HEATING THAT TAKES PLACE. EARLIER RUNS OF THE HRRR HAD SHOWN VERY LITTLE DEVELOPMENT THIS AFTERNOON BUT THE 10Z AND 11Z RUNS HAVE TAKEN A BIT OF A DIFFERENT TURN AND SHOW WIDESPREAD DEVELOPMENT WITH A SLOW DRIFT TOWARDS THE EAST COAST BY LATE AFTERNOON BUT THEN THE 12Z RUN IS SHOWING MAINLY SEA BREEZE DEVELOPMENT. SO LATER UPDATES WILL BASICALLY TAKE ON THE PATTERN OF SUBTLE CHANGES THAT MAY CHANGE THE LOCATION AND MOVEMENT OF ANY CONVECTIVE DEVELOPMENT THAT MAY TAKE PLACE. KOB && .PREV DISCUSSION... /ISSUED 708 AM EDT SUN JUL 21 2013/ AVIATION... VFR CONDITIONS WILL PREVAIL. HIGH PRESSURE WILL CONTINUE TO BUILD INTO SOUTH FLORIDA THROUGH THE END OF THE TAF PERIOD...BRINGING IN DRIER LOW/MID LEVEL AIR TO THE REGION. LIGHT WINDS THIS MORNING WILL BECOME SOUTHEAST AROUND 10 KNOTS FOR THE EAST COAST TAF SITES BY THE AFTERNOON AS THE SEA BREEZE PUSHES INLAND. FOR KAPF...WINDS WILL SHIFT TO THE SOUTHWEST AROUND 8-10 KNOTS AS THE SEA BREEZE PUSHES INLAND. WITH THE DRIER AIR...EXPECT SHOWER AND THUNDERSTORM ACTIVITY TO BE LIMITED AND REMAIN ACROSS THE INTERIOR. LIGHT WINDS ARE EXPECTED AGAIN OVERNIGHT. PREV DISCUSSION... /ISSUED 337 AM EDT SUN JUL 21 2013/ DISCUSSION... THE WEAK TROPICAL WAVE THAT AFFECTED THE WEATHER ON SATURDAY WILL CONTINUE TO PUSH WESTWARD ACROSS SOUTH FLORIDA THIS MORNING AND MOVE INTO THE WESTERN GULF ON SUNDAY AFTERNOON. FOR SUNDAY...DRIER AIR WILL BEGIN TO SPREAD NORTH INTO THE AREA AS THE RIDGE BEGINS TO BUILD OVER FLORIDA AND THE WEAK TROUGH LIFTS AWAY FROM THE AREA. HOWEVER...LINGERING MOISTURE OVER THE NORTHERN HALF OF THE CWA...OR AROUND THE LAKE REGION...WITH PWAT VALUES AROUND 2" COMBINED WITH SW LOW-LEVEL FLOW WILL BE ENOUGH TO THE KEEP THE AFTERNOON/EVENING SHOWERS/TSTMS IN THE FORECAST. BETWEEN NOW AND SUNRISE SHOWERS AND THUNDERSTORMS ARE FORECAST FOR PORTIONS OF THE ATLANTIC AND GULF WATERS. THE LARGE SCALE WEATHER PATTERN INDICATES THAT AN AREA OF HIGH PRESSURE DEVELOPS OVER FLORIDA AS THE BERMUDA HIGH EXTENDS WESTWARD FROM SUNDAY THROUGH TUESDAY. THIS IS FORECAST TO BRING A MORE TYPICAL SUMMER PATTERN OF AFTERNOON AND EVENING CONVECTION DRIVEN BY SEA BREEZE BOUNDARIES. FOR MONDAY AND TUESDAY IT CAN BE SEEN IN THE SOUNDING FORECASTS AND NEMS GFS AND NRL AEROSOL MODELS THE PRESENCE OF SOME SAHARAN DUST. FOR WEDNESDAY, THE SUBTROPICAL HIGH PRESSURE STRENGHTENS IN THE MIDDLE PORTIONS OF THE ATLANTIC OCEAN CAUSING THE TROUGH OVER THE EASTERN PORTIONS OF THE US TO AMPLIFY. THIS IS EXPECTED TO COOL SOMEWHAT THE MID LEVEL TEMPERATURES WHICH COULD POTENTIALLY INCREASE THE CONVECTION BY MID WEEK. THE COMBINATION OF WEAK SOUTHWESTERLY FLOW AND A LITTLE BIT MORE MOISTURE IS EXPECTED TO INCREASE THE SHOWERS AND THUNDERSTORMS OVER THE NORTHERN AND EASTERN SECTIONS OF SOUTH FLORIDA, THE LAKE REGION AND IN GENERAL PALM BEACH AND BROWARD COUNTIES. BETWEEN WEDNESDAY AND FRIDAY THE EAST COAST TROUGH WEAKENS GRADUALLY BUT IT STILL SHOWS A GENERAL WEAKNESS OVER FLORIDA. FOR FRIDAY, THE RIDGE OVER NORTHERN MEXICO EXPANDS EASTWARD INCREASING THE 500 MB TEMPERATURES OVER NORTH FLORIDA AND SOUTH GEORGIA TO -4C. FOR SOUTH FLORIDA WE STAY IN THE -6 RANGE WHICH IS VERY UNFAVORABLE FOR ANY WIDESPREAD CONVECTION TO OCCUR. THE RISK OF RIP CURRENTS WILL BE SLIGHT FOR THE ATLANTIC BEACHES FOR SUNDAY. MARINE... GENERAL EAST TO SOUTHEAST WIND IS EXPECTED THROUGH TUESDAY AT SPEEDS OF LESS THAN 10 TO 12 KNOTS OUTSIDE OF SCATTERED SHOWERS /THUNDERSTORMS. THE WIND WILL BEGIN TO VEER TO A SOUTH OR SOUTHWEST DIRECTION LATER IN THE WEEK AS THE SURFACE RIDGE SHIFTS TO THE SOUTH AND THE EAST COAST AMPLIFIES DUE TO A BLOCKING HIGH IN THE ATLANTIC. FIRE WEATHER... NO FIRE WEATHER CONCERNS OR FOG IS ANTICIPATED THROUGHOUT THE FORECAST PERIOD. THE TYPICAL AREA WITH LOWER RELATIVE HUMIDITIES, GLADES AND HENDRY, WILL MAINTAIN VALUES ABOVE 50 PERCENT THIS WEEKEND AND COMING WEEK. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 89 76 88 76 / 20 20 30 10 FORT LAUDERDALE 89 79 89 78 / 20 20 30 10 MIAMI 90 77 88 77 / 20 20 20 10 NAPLES 90 75 89 75 / 20 10 20 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
743 AM EDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 450 AM EDT SUN JUL 21 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A ZONAL FLOW OVER THE UPPER GREAT LAKES. AT THE SFC...HIGH PRESSURE DOMINATES THE UPPER GREAT LAKES. THE CLEAR SKIES AND LIGHT WINDS HAVE ALLOWED TEMPS EARLY THIS MORNING TO FALL INTO THE 40S WITH EVEN A FEW LOCATIONS REACHING THE MID TO UPPER 30S. TODAY...AS THE SFC HIGH SHIFTS EAST OF THE AREA...SRLY FLOW AND WAA WILL INCREASE AHEAD OF APPROACHING SHORTWAVE AND FRONTAL SYSTEM OVER THE NRN PLAINS. TEMPS SHOULD CLIMB INTO THE LOWER TO MID 70S INLAND WITH LOWER READINGS IN THE MID TO UPPER 60S ALONG THE GREAT LAKES. MODELS INDICATE SOME INCREASE IN 305K ISENTROPIC ASCENT OVER FAR WRN UPR MI LATE IN THE DAY ALTHOUGH BEST MOISTURE LIFT SHOULD STAY SOUTH AND WEST. WILL MAINTAIN GOING FCST OF SLIGHT CHANCE POPS OVER THE FAR WEST. TONIGHT...INCREASING 925-700 MB THETA-E ADVECTION AND 305K ISENTROPIC ASCENT SHOULD LEAD TO INCREASED CHCS FOR SHRA AND TSRA ESPECIALLY AFT MIDNIGHT AS SHORTWAVE APPROACHED FM THE WEST. LIMITING FACTOR FOR TSRA WILL BE LACK OF ELEVATED INSTABILITY AS MUCAPES ONLY A FEW HUNDRED J/KG. WILL KEEP HIGHER CHC POPS OVER FAR WEST AND TAPER TO LOW CHC 20-30 PCT POPS OVER CENTRAL COUNTIES. EXPECT LOWS GENERALLY IN THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 450 AM EDT SUN JUL 21 2013 MOST TIME SPENT ON LONG TERM WAS WITH PRECIP CHANCES MON/MON NIGHT AND ASSESSING SEVERE STORM THREAT FOR MON AFTERNOON/EVENING. LOOKING FIRST AT THE LARGE SCALE...AN UPPER TROUGH OVER THE ERN HALF OF THE CONUS WILL BE STEMMING FROM A CLOSED LOW OVER NRN QUEBEC AND AN UPPER RIDGE WILL BE OVER THE WRN CONUS AT 12Z MON. A PIECE OF UPPER ENERGY WILL MOVE ACROSS THE REGION MON INTO EARLY MON NIGHT...FOLLOWED BY OTHER SMALLER SCALE ENERGY THU NIGHT THROUGH SAT...BUT THE OVERALL PATTERN REMAINS SIMILAR THROUGH THE EXTENDED. THIS MEANS...FOR THE MOST PART...THAT COOLER WEATHER IS HERE TO STAY FOR MUCH OF THE NEXT WEEK AT LEAST. FOR THE SPECIFICS... MON/MON NIGHT...THERE WILL BE PRECIP MOVING INTO THE WRN CWA EARLY MON AS THE UPPER TROUGH AND SFC TROUGH/COLD FRONT MOVE IN. THINK THE BEST PRECIP CHANCES WILL BE DURING THE AFTERNOON/EARLY EVENING AS THE COLD FRONT MOVES THROUGH A POTENTIALLY UNSTABLE AIRMASS. QUESTIONS IS HOW MUCH CLEARING WILL RESULT AFTER MORNING RAIN...WHICH WILL EFFECT HOW MUCH INSTABILITY EXISTS IN THE AFTERNOON. IF WE CAN GET GOOD CLEARING...SBCAPE VALUES MAY BE 800-1200J/KG /HIGHEST OVER SCENTRAL UPPER MI/...AND STRONGLY VEERING WINDS THROUGH THE ATMOSPHERE WILL LEAD TO AROUND 40KTS OF 0-6KM BULK SHEAR. IF OPTIMAL CONDITIONS FOR CONVECTION DO MATERIALIZE...THEN SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS WOULD BE POSSIBLE...WITH THE BEST CHANCES OVER SCENTRAL UPPER MI. HOWEVER...AT THIS TIME...THINK THE COVERAGE OF ANY SEVERE WEATHER WILL BE MORE LIMITED DUE TO DRY AIR. FOR NOW WILL CONTINUE MENTION OF SEVERE CHANCES IN HWO/EHWO BUT STILL TOO UNCERTAIN TO PUT IN GRIDS. MON LOOKS LIKE THE WARMEST DAY IN THE NEXT WEEK AHEAD OF THE COLD FRONT...WITH HIGHS IN THE 70S TO MID 80S. POSTFRONTAL TUESDAY SHOULD BE COOLER AND SIMILAR TO YESTERDAY...WITH HIGHS AROUND 60 NEAR LAKE SUPERIOR TO THE LOW 70S SOUTH CENTRAL. SKIES SHOULD BE CLEARING BY THE AFTERNOON. WED WILL BE SLIGHTLY WARMER THAN TUESDAY AS TEMPS RECOVER SOME FROM THE COLD FRONT. SHOULD SEE SOME INCREASE IN CLOUDS FROM W TO E DURING THE AFTERNOON/EVENING AS A MORE MILD PIECE OF UPPER ENERGY SLIDES ACROSS THE CWA...BUT NO PRECIP IS EXPECTED. THERE IS MORE UNCERTAINTY LATER IN THE WEEK WHEN LOOKING AT MORE SIGNIFICANT UPPER ENERGY SLIDING INTO THE REGION...BUT PRECIP WILL CERTAINLY BE POSSIBLE LATER INTO THE WEEK. TEMPERATURES WILL CLIMB ANOTHER COUPLE OF DEGREES ON THURSDAY...BUT SHOULD AGAIN FALL INTO THE WEEKEND AS THE UPPER TROUGH MOVES OVERHEAD. USED A GENERAL CONSENSUS OF MODEL GUIDANCE FOR THIS PART OF THE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 729 AM EDT SUN JUL 21 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. EXPECT INCREASING MID CLOUDS LATE IN THE DAY AND TONIGHT AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. SOME SHRA ARE POSSIBLE AT KIWD AND KCMX LATE TONIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 450 AM EDT SUN JUL 21 2013 HIGH PRESSURE WILL KEEP WINDS GENERALLY LIGHT TODAY OVER THE NORTHERN GREAT LAKES. SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS LATE TONIGHT AND MONDAY AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND THE TROUGH/COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS TUE NIGHT THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...TITUS AVIATION...VOSS MARINE...VOSS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
1028 AM CDT SUN JUL 21 2013 .UPDATE... MAKING SOME ADJUSTMENTS TO THE FORECAST FOR THE FIRST COUPLE OF PERIODS...INCLUDING ADJUSTING POPS A LITTLE FOR TODAY...CUTTING POPS FOR TONIGHT...AND TWEAKING TEMPS UP A HAIR FOR THIS AFTERNOON. && .SHORT TERM... WATER VAPOR AND RUC STREAMLINE ANALYSIS SHOW REMNANT UPPER LEVEL LOW CURRENTLY OVER THE LOWER DELTA REGION. SHORT TERM MODELS SHOW THIS LOW OPENING UP AND DRIFTING EAST TODAY. BLENDED TOTAL PW PRODUCT SHOWS BEST DEEP MOISTURE OVER S/E AREAS AHEAD OF UPPER LOW...BUT EVEN RIGHT UNDER THE UPPER LOW WHERE A MIN IN MOISTURE EXISTS...PW VALUES STILL AROUND 1.8 INCHES. CU IS BEGINNING TO FORM ACROSS THE AREA...AND WITH CONTINUED HEATING AND SUPPORT FROM UPPER SYSTEM EXPECT CONVECTIVE COVERAGE TO INCREASE THROUGH THE AFTERNOON. SHORT TERM MESOSCALE MODELS AGREE ON BEST COVERAGE OVER S/E AREAS...AND THIS GENERALLY SEEMS SUPPORTED BY LATEST TRENDS IN OBSERVATIONAL DATA. DID TWEAK POPS UP A HAIR TO GET ALL AREAS TO AT LEAST 30 PCT BUT OVERALL TREND OF GOING FORECAST LOOKS OK. MORNING SOUNDING ANALYSIS AND LOCAL RUC MICROBURST PARAMETER SUGGEST THAT CURRENT WORDING IN HWO AND GRAPHICAST OF SOME STRONG STORMS SEEMS REASONABLE. RUC SHOWS 500 MB TEMPS COOLING A DEG OR TWO MOST OF AREA AS MID LEVEL COLD POOL WITH UPPER LOW MOVES ACROSS...AND THIS SHOULD HELP ENHANCE INSTABILITY AND LAPSE RATES A BIT. THUS WOULD CERTAINLY NOT RULE OUT A COUPLE OF SEVERE STORMS THIS AFTERNOON...PARTICULARLY WITH ANY CELL/BOUNDARY MERGERS. WITH PRETTY COMPLETE LACK OF CLOUDINESS BEFORE BUILDING CU...TEMPS HAVE WARMED QUITE QUICKLY THIS MORNING. ADJUSTED DIURNAL CURVE FOR MORE RAPID WARMUP AND TWEAKED MAXES UP A DEG OR TWO. WITH REGARD TO TONIGHT...THINKING THAT 00Z GFS MAY HAVE BEEN A WET ANOMALY BASED ON GEFS GUIDANCE...LATEST 06Z GFS...AND 00Z ECMWF. MAIN CONCERN FOR CONVECTION TONIGHT IS LIKELY WAVE THAT HAS BEEN PRODUCING SOME CONVECTION OVER NE OK THIS MORNING...AND IT IS CERTAINLY PLAUSIBLE THAT THIS SYSTEM COULD INCITE SOME OVERNIGHT CONVECTION ESPECIALLY OVER NORTHERN AREAS. HOWEVER...HIGH CHANCE TO CATEGORICAL POPS IN CURRENT FORECAST AS PROVIDED BY 00Z GFS SEEM A BIT BULLISH...AND WILL REDUCE POPS BY 15-30 PCT AREA WIDE FOR TONIGHT. && .AVIATION... VFR CONDITIONS WERE BEING OBSERVED AT 14Z AND WILL PREVAIL AT ALL SITES THROUGH 18Z. MODELS INDICATE GREATEST COVERAGE OF TSTMS THIS AFTN/EVNG WL BE ACROSS THE SRN HALF OF THE AREA. BRIEF IFR CONDITIONS CAN BE EXPECTED AROUND THE STORMS FROM 18Z-04Z. VFR CONDITIONS WL RESUME AREAWIDE THIS EVNG AND CONTINUE THROUGH 09Z MON. AFTER 09Z...MVFR VSBYS WL BE PSBL MAINLY ACROSS THE SRN HALF OF THE AREA. CONVECTION MAY GET AN EARLY START ACROSS THE NORTH MONDAY MORNING DUE TO A DISTURBANCE IN THE NW FLOW ALOFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 93 72 90 75 / 31 43 55 36 MERIDIAN 92 72 91 72 / 40 47 62 45 VICKSBURG 94 74 92 73 / 32 44 49 29 HATTIESBURG 92 73 92 74 / 45 27 64 42 NATCHEZ 93 74 90 75 / 44 27 53 27 GREENVILLE 95 74 92 76 / 31 58 52 39 GREENWOOD 94 72 91 75 / 30 57 56 44 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ AEG/MME
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1019 AM CDT SUN JUL 21 2013 .UPDATE... UPDATED TO ADJUST MORNING AND AFTERNOON POPS && .DISCUSSION... 12Z UPPER AIR ANALYSIS INDICATED THAT A SEASONABLY STRONG SHORTWAVE TROUGH EXTNDD FM WRN MN INTO CNTRL NEB. THIS WAS SPREADING LARGE-SCALE ASCENT ACROSS THE FA THIS MORNING. THE 12Z KOAX RAOB INDCD AROUND 1400 J/KG OF MUCAPE WITH LITTLE CAPPING. THUS THE COMBINATION OF THE FORCING AND WEAKLY CAPPED ATMOSPHERE WAS LEADING TO SCT TSRA OVER FAR SE NEB AND SW IA. THIS SHOULD CONT TO SHIFT EWD THIS MORNING ASSOCIATED WITH THE SHORTWAVE TROUGH. WHAT HAPPENS IN THE WAKE OF THIS MORNING ACTIVITY IS A BIT UNCLEAR. MODIFYING THE 12Z SOUNDING YIELDS LITTLE CAPPING AS TEMPERATURES CLIMB INTO THE MID 80S WITH AROUND 2000 J/KG OF MLCAPE. THE NEGATIVE THOUGH IS THE SUBSIDENCE THAT WILL BE SPREADING INTO THE AREA LATER THIS MORNING IN THE WAKE OF THE MORNING SHORTWAVE TROUGH. THIS IS LIKELY TO COMBINE WITH A LACK OF A SFC BOUNDARY TO FOCUS CONVERGENCE TO MAKE REDEVELOPMENT THIS AFTERNOON PRETTY UNLIKELY. WILL MAINTAIN A SCHC OF AFTERNOON STORMS OVER THE ERN FA OTHERWISE WE FEEL IT WILL BE A PRETTY DRY AFTERNOON. THE OTHER ELEMENTS OF THE FORECAST APPEAR ON TRACK ATTM. && .PREV DISCUSSION... /ISSUED 611 AM CDT SUN JUL 21 2013/ AVIATION... 12Z TAFS FOR KOFK...KLNK AND KOMA. FOR THE MAJORITY OF THE TAF PERIOD WE EXPECT VFR FLIGHT CONDITIONS AND RELATIVELY QUIET WEATHER. THE FORECAST CHALLENGE IS PREDICTING WHEN AND WHERE SHOWERS AND THUNDERSTORMS MIGHT DEVELOP AND CONSEQUENTLY EFFECT THE TAF SITES. THIS TIME OF YEAR...IN THESE WEATHER PATTERNS...THE PREDICTABILITY OF CONVECTION IS LOW AND THE UNCERTAINTY IS HIGH. GIVEN THAT...WILL KEEP SPECIFIC MENTION OF TSRA OUT OF THE TAFS FOR NOW AND REFINE AS THE PATTERN BECOMES MORE SUPPORTIVE OF THUNDERSTORM DEVELOPMENT. THERE IS ONE CLUSTER OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING THROUGH WESTERN NEBRASKA AND INTO CENTRAL NEBRASKA...BUT AT THIS TIME THAT AREA APPEARS TO BE MOVING INTO SOUTH CENTRAL NEBRASKA AND WILL NOT MOVE FAR ENOUGH EAST TO EFFECT THE TAF SITES. ADDITIONAL STORM DEVELOPMENT COULD OCCUR IN EASTERN NEBRASKA THIS AFTERNOON. NIETFELD PREV DISCUSSION... /ISSUED 301 AM CDT SUN JUL 21 2013/ DISCUSSION... FORECASTING AREAL EXTENT OF CONVECTION THROUGH THE FORECAST WILL BE A SIGNIFICANT CHALLENGE AS THE REGION REMAINS IN NORTHWEST FLOW THIS WEEK. FIRST ROUND OF CONVECTION IS MOVING INTO EASTERN NEBRASKA EARLY THIS MORNING...BUT WILL ALSO HAVE TO OVERCOME A POCKET OF DRY AIR AT H85. CONTINUED THETAE ADVECTION SHOULD HELP TO ERODE THIS DRY POCKET AND CONTINUE TRIGGER STORMS THIS MORNING THAT WILL CONTINUE TO MOVE EASTWARD THROUGH THE AREA INTO WESTERN IOWA BEFORE DISSIPATING THROUGH MID TO LATE MORNING. WHILE HEAVY RAINS ARE NOT WIDESPREAD...SOME VERY SPOTTY LOCATIONS WHERE LIGHTNING IS OCCURRING ARE LIKELY PICKING UP SOME DECENT MEANINGFUL RAINFALL. MEANWHILE...WATER VAPOR IMAGERY INDICATES ANOTHER SUBTLE WAVE IS LIKELY MOVING THROUGH WESTERN SOUTH DAKOTA. ANOTHER CLUSTER OF STORMS HAS REFIRED ACROSS THAT AREA...MOVING INTO NORTH CENTRAL NEBRASKA. BOTH THE NAM AND RAP SEEM TO HAVE PICKED UP ON THIS FEATURE AND MOVE IT THROUGH THE FORECAST AREA THIS AFTERNOON...WHICH COULD BE THE TRIGGER FOR ADDITIONAL STORMS AS WE HEAD THROUGH PEAK HEATING. FORWARD SPEED SUGGESTS THAT THIS MAY MOSTLY BE OUT OF THE AREA BY EARLY THIS EVENING. THE REMAINDER OF SUNDAY NIGHT AND MONDAY MORNING SHOULD BE DRY. A FRONTAL BOUNDARY MOVING INTO THE REGION COULD TRIGGER ISOLATED AFTERNOON STORMS IN NORTHEAST NEBRASKA. TEMPS AHEAD OF THE FRONT WILL PROBABLY REACH THE LOWER 90S ONCE AGAIN. SHOULD ALSO SEE A CHANCE OF THUNDERSTORMS MONDAY NIGHT AS THE FRONT MOVES THROUGH THE AREA. THE NEXT WAVE APPEARS ON THE HORIZON BY TUESDAY AFTERNOON THEN MOVES THROUGH THE REGION TUESDAY NIGHT. WEDNESDAY AND WEDNESDAY NIGHT SHOULD BE DRY...BUT ANOTHER WAVE MOVES INTO THE AREA ON THURSDAY AND LINGERS THROUGH FRIDAY. THE GFS SUGGESTS THAT WE MIGHT REMAIN DRY ON SATURDAY...BUT THE ECMWF HAS YET ANOTHER SURGE OF MOISTURE MOVING THROUGH. NEVERTHELESS...CONFIDENCE DECREASES IN SPECIFICS TOWARD THE END OF THE WEEK. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
611 AM CDT SUN JUL 21 2013 .AVIATION... 12Z TAFS FOR KOFK...KLNK AND KOMA. FOR THE MAJORITY OF THE TAF PERIOD WE EXPECT VFR FLIGHT CONDITIONS AND RELATIVELY QUIET WEATHER. THE FORECAST CHALLENGE IS PREDICTING WHEN AND WHERE SHOWERS AND THUNDERSTORMS MIGHT DEVELOP AND CONSEQUENTLY EFFECT THE TAF SITES. THIS TIME OF YEAR...IN THESE WEATHER PATTERNS...THE PREDICTABILITY OF CONVECTION IS LOW AND THE UNCERTAINTY IS HIGH. GIVEN THAT...WILL KEEP SPECIFIC MENTION OF TSRA OUT OF THE TAFS FOR NOW AND REFINE AS THE PATTERN BECOMES MORE SUPPORTIVE OF THUNDERSTORM DEVELOPMENT. THERE IS ONE CLUSTER OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING THROUGH WESTERN NEBRASKA AND INTO CENTRAL NEBRASKA...BUT AT THIS TIME THAT AREA APPEARS TO BE MOVING INTO SOUTH CENTRAL NEBRASKA AND WILL NOT MOVE FAR ENOUGH EAST TO EFFECT THE TAF SITES. ADDITIONAL STORM DEVELOPMENT COULD OCCUR IN EASTERN NEBRASKA THIS AFTERNOON. NIETFELD && .PREV DISCUSSION... /ISSUED 301 AM CDT SUN JUL 21 2013/ .DISCUSSION... FORECASTING AREAL EXTENT OF CONVECTION THROUGH THE FORECAST WILL BE A SIGNIFICANT CHALLENGE AS THE REGION REMAINS IN NORTHWEST FLOW THIS WEEK. FIRST ROUND OF CONVECTION IS MOVING INTO EASTERN NEBRASKA EARLY THIS MORNING...BUT WILL ALSO HAVE TO OVERCOME A POCKET OF DRY AIR AT H85. CONTINUED THETAE ADVECTION SHOULD HELP TO ERODE THIS DRY POCKET AND CONTINUE TRIGGER STORMS THIS MORNING THAT WILL CONTINUE TO MOVE EASTWARD THROUGH THE AREA INTO WESTERN IOWA BEFORE DISSIPATING THROUGH MID TO LATE MORNING. WHILE HEAVY RAINS ARE NOT WIDESPREAD...SOME VERY SPOTTY LOCATIONS WHERE LIGHTNING IS OCCURRING ARE LIKELY PICKING UP SOME DECENT MEANINGFUL RAINFALL. MEANWHILE...WATER VAPOR IMAGERY INDICATES ANOTHER SUBTLE WAVE IS LIKELY MOVING THROUGH WESTERN SOUTH DAKOTA. ANOTHER CLUSTER OF STORMS HAS REFIRED ACROSS THAT AREA...MOVING INTO NORTH CENTRAL NEBRASKA. BOTH THE NAM AND RAP SEEM TO HAVE PICKED UP ON THIS FEATURE AND MOVE IT THROUGH THE FORECAST AREA THIS AFTERNOON...WHICH COULD BE THE TRIGGER FOR ADDITIONAL STORMS AS WE HEAD THROUGH PEAK HEATING. FORWARD SPEED SUGGESTS THAT THIS MAY MOSTLY BE OUT OF THE AREA BY EARLY THIS EVENING. THE REMAINDER OF SUNDAY NIGHT AND MONDAY MORNING SHOULD BE DRY. A FRONTAL BOUNDARY MOVING INTO THE REGION COULD TRIGGER ISOLATED AFTERNOON STORMS IN NORTHEAST NEBRASKA. TEMPS AHEAD OF THE FRONT WILL PROBABLY REACH THE LOWER 90S ONCE AGAIN. SHOULD ALSO SEE A CHANCE OF THUNDERSTORMS MONDAY NIGHT AS THE FRONT MOVES THROUGH THE AREA. THE NEXT WAVE APPEARS ON THE HORIZON BY TUESDAY AFTERNOON THEN MOVES THROUGH THE REGION TUESDAY NIGHT. WEDNESDAY AND WEDNESDAY NIGHT SHOULD BE DRY...BUT ANOTHER WAVE MOVES INTO THE AREA ON THURSDAY AND LINGERS THROUGH FRIDAY. THE GFS SUGGESTS THAT WE MIGHT REMAIN DRY ON SATURDAY...BUT THE ECMWF HAS YET ANOTHER SURGE OF MOISTURE MOVING THROUGH. NEVERTHELESS...CONFIDENCE DECREASES IN SPECIFICS TOWARD THE END OF THE WEEK. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1035 AM EDT SUN JUL 21 2013 .SYNOPSIS... AN UPPER LEVEL TROUGH WILL SLOWLY AMPLIFY OVER THE REGION THROUGH EARLY IN THE WEEK. MEANWHILE...A SURFACE TROUGH OF LOW PRESSURE WILL REMAIN OVER THE AREA THROUGH MID TO LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1035 AM SUNDAY... THE LATEST SURFACE ANALYSIS CONTINUED TO SHOW A WEAK GRADIENT OVER CENTRAL NORTH CAROLINA...WITH A PERSISTENT SURFACE TROUGH WEST OF THE YADKIN RIVER. THE MORNING UPPER-LEVEL ANALYSES SHOWED A FAIRLY PRONOUNCED 850MB TROUGH OVER CENTRAL NORTH CAROLINA...CAPTURED BY THE RUC AND FORECAST TO LINGER OVER THE AREA WHILE WEAKENING THROUGH THE AFTERNOON. ON WATER VAPOR...IT SEEMED AS IF CENTRAL NORTH CAROLINA WAS IN ALMOST SUBTLE RIDGING BETWEEN A WEAK UPPER LOW OVER THE SOUTHERN MISSISSIPPI RIVER AND A WEAK WAVE MOVING EAST ACROSS THE STATE. IT WAS INTERESTING TO NOTE THAT THE PRECIPITABLE WATER VALUE ON THE KRNK SOUNDING WAS BELOW 1.4 INCHES THIS MORNING. IT WAS HIGHER AT KGSO COMPARED TO 12Z SATURDAY. DOWNDRAFT CAPE ON THE SPC MESOANALYSIS WAS WEAKER THAN SATURDAY...AND OTHER PARAMETERS SUCH AS THE MID-LEVEL LAPSE RATES AND THETA-E DIFFERENCE ALOFT WERE SLIGHTLY LESS AS WELL. THE LATEST RUC FORECASTS NOTICEABLE 850MB SUBSIDENCE OVER CENTRAL NORTH CAROLINA FOR THE AFTERNOON...WITH SOMEWHAT BETTER LIFT MOVING IN OVER THE NORTHWEST PIEDMONT AND THE SANDHILLS LATE TODAY AND THIS EVENING. MOST OF THE CONVECTIVE-ALLOWING MODELS DEVELOP SCATTERED SHOWERS AND THUNDERSTORMS OVER CENTRAL NORTH CAROLINA THIS AFTERNOON...AND FOR THE MID-MORNING UPDATE OPTED TO CONCENTRATE THE BETTER CHANCES OVER THE NORTHWEST PIEDMONT...NEAR WHAT MAY END UP BEING SOME DIFFERENTIAL HEATING BASED ON THE LATEST VISIBLE IMAGES. A STORM OR TWO COULD BECOME STRONG...BUT THE PREPONDERANCE OF THE CURRENT EVIDENCE SUGGESTS THE POTENTIAL FOR A SEVERE STORM IS LIMITED. WILL REVIEW LATER DATA TO TRY TO FOCUS BETTER CHANCES FOR THIS EVENING... AS BASED ON THE LATEST RUC THIS WOULD BE MAINLY NORTH OF U.S. 64 AND OVER THE SANDHILLS WHERE THE GREATER 850MB LIFT IS CONCENTRATED. KEPT HIGH TEMPERATURES AS IS GIVEN AT LEAST SOME EXPECTED SUN... THOUGH HIGHS ARE FORECAST BELOW FULL SUN 1000-850MB THICKNESS VALUES WHICH WOULD SUGGEST HIGHS A CATEGORY WARMER. LOWS TONIGHT IN THE LOWER 70S. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 300 AM SUNDAY... WEAK SHORT-WAVE ENERGY CURRENTLY OVER THE NORTHERN PLAINS WILL UNDERGO SLIGHT AMPLIFICATION(ALONG WITH AMPLIFICATION OF THE LONG WAVE TROUGH AS WELL)AS IT PROGRESSES EAST-SOUTHEASTWARD INTO THE OHIO AND TN VALLEY ON MONDAY...REACHING THE CENTRAL-SOUTHERN BY DAYBREAK TUESDAY. IN RESPONSE TO THE ATTENDANT UPSTREAM HEIGHT FALLS ON THE ORDER OF 20 TO 30 METERS...A WEAK WAVE OF LOW PRESSURE IS FORECAST TO DEVELOP ALONG THE SURFACE TROUGH OF LOW PRESSURE BISECTING THE VIRGINIAS AND CAROLINAS...WHICH WILL SERVE TO STRENGTHEN THE LOW-LEVEL MOISTURE CONVERGENCE AS A POOL OF +2.0 PWATS RESIDES OVER THE SOUTHEASTERN STATES. ADDITIONALLY...THERE IS ALSO THE POTENTIAL THAT REMNANT CENTER ASSOCIATED WITH THE WEAK UPPER LOW CURRENTLY OVER LOUISIANA COULD MOVE NORTHEASTWARD OVER THE AREA LATE MONDAY AND INTO MONDAY NIGHT...FURTHER AUGMENTING ASCENT OVER THE AREA. AS SUCH...CONVECTION MONDAY AFTERNOON IS EXPECTED TO BE MORE ROBUST THAN IN PREVIOUS DAYS...WITH THE THREAT OF CONVECTION PERSISTING THROUGH THE OVERNIGHT HOURS. CONFIDENCE IN THE TIMING/IMPACTS OF THIS DISTURBANCE IS LOW AT THIS POINT...ESPECIALLY WITH THE 00Z/21 GFS COMPLETELY SHEARING THE DISTURBANCE COMPLETING APART OVER GEORGIA/SC. HOW THIS FEATURES EVOLVES WILL LIKELY BE THE DIFFERENCE BETWEEN LIKELY OR CHANCE POPS ACROSS CENTRAL NC MONDAY AFTERNOON/EVENING. HIGH +2.0 PWATS COULD RESULT IN ONE OR TWO WET MICROBURSTS...MAINLY DURING PEAK AFTERNOON HEATING/DESTABILIZATION...WITH A MORE ORGANIZED SEVERE THREAT BEING IMPEDED BY WEAK SHEAR AND WEAK MID-LEVEL LAPSE RATES. ALSO...WITH LOCAL RIVER....STREAMS AND CREEKS STILL RUNNING HIGH...FLASH FLOODING WILL ALSO BE POSSIBLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 245 AM SUNDAY... TUESDAY AND TUESDAY NIGHT: WITH THE PERSISTENT SOUTHWEST FLOW...THE ATMOSPHERE WILL REMAIN SUFFICIENTLY MOIST AND UNSTABLE. THE SURFACE TROUGH IS EXPECTED TO STALL OVER THE MID ATLANTIC...WITH THE UPPER LEVEL TROUGH SLOWLY DRIFTING EAST OVER THE AREA. THE 00Z RUN OF THE GFS PICKS UP ON A H3 DISTURBANCE MOVING THROUGH NC TUESDAY AFT/EVE...WHICH SHOULD HELP ENHANCE THE DIURNALLY DRIVEN CONVECTION. BEST LIFT WILL TRANSLATE FROM NW TO SE THROUGH CENTRAL NC AHEAD OF THE BACKDOOR COLD FRONT...WHICH WPC PREDICTS WILL MOVE TROUGH THE AREA TUESDAY NIGHT AND INTO WEDNESDAY...POTENTIALLY STALLING ALONG THE COAST. AS SUCH...WILL SHOW BEST CHANCES FOR CONVECTION FROM THE TRIANGLE SE BETWEEN 18Z TUESDAY AND 06Z WEDNESDAY. HIGH TEMPS IN THE UPPER 80S TO LOW 90S AND OVERNIGHT LOWS IN THE LOW TO MID 70S EXPECTED. WEDNESDAY THROUGH SATURDAY: LOW LEVEL WINDS MAY TEMPORARILY BECOME MORE WNW BEHIND THE BACKDOOR FRONT SHOULD IT INDEED MOVE THROUGH THE AREA AND STALL ALONG THE COAST BY WEDNESDAY...WHICH WOULD YIELD A SUBSEQUENT DRYING OF THE MID LEVELS. CURRENT MODEL AGREEMENT WITH REGARD TO THE TROUGH...AT BOTH THE SURFACE AND ALOFT...LINGERING OVER THE AREA THROUGH THE END OF THE WEEK IS GOOD. THE LOCATION OF THE TROUGH AXIS WILL PLAY A ROLE IN WHERE THE BEST MOISTURE IS AVAILABLE...WHICH CURRENTLY IS EXPECTED ALONG THE COAST. DEPENDING ON THEIR TIMING...A SERIES OF UPPER LEVEL DISTURBANCES MOVING OVER THE AREA COULD ENHANCE DIURNAL CONVECTIVE ACTIVITY THROUGH THE PERIOD. OF LESSER CERTAINTY IS THE COVERAGE AND LOCATION OF THE ANTICIPATED AFT/EVE SHOWERS AND STORMS. FOR NOW WILL CONTINUE TO INDICATE BEST PRECIP CHANCES DURING THE AFT/EVE HOURS ACROSS THE AREA...WITH SLIGHTLY HIGHER CHANCES ACROSS THE EAST WHERE THE BEST MOISTURE IS EXPECTED. ONLY SMALL CHANGES IN TEMPS FROM DAY TO DAY THROUGH THE PERIOD...HIGHS MAINLY IN THE MID 80S TO AROUND 90 DEGREES WITH OVERNIGHT LOWS MAINLY IN THE UPPER 60S TO LOW 70S. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... AS OF 1035 AM SUNDAY... 24-HR TAF PERIOD: MVFR CEILINGS WILL LIFT SLOWLY...EVENTUALLY BECOMING MOSTLY VFR BY AFTERNOON. DIURNAL SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE AT ALL TAF SITES THIS AFTERNOON MAINLY FROM 20Z-02Z. -CBL/DJF LOOKING AHEAD: EXPECT AN ABOVE NORMAL CHANCE FOR SHOWERS AND THUNDERSTORMS MONDAY THROUGH THURSDAY AS A SLOW MOVING UPPER LEVEL TROUGH DEVELOPS OVER THE EASTERN UNITED STATES. THOUGH CONVECTION WILL BE POSSIBLE DURING THE DAY AND AT NIGHT...THE BEST CHANCE EACH DAY WILL BE IN THE TYPICAL 18-03Z TIME FRAME. SUB-VFR CONDITIONS ASSOCIATED WITH FOG OR STRATUS WILL BE POSSIBLE EACH MORNING...PRIMARILY IN THE 08-14Z TIME FRAME. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/DJF SHORT TERM...CBL LONG TERM...KMC AVIATION...CBL/VINCENT/DJF
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
646 AM EDT SUN JUL 21 2013 .SYNOPSIS... A TYPICAL SUMMER PATTERN OF HIGH PRESSURE OFFSHORE AND A TROUGH OF LOW PRESSURE INLAND WILL PERSIST THROUGH TUESDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST WEDNESDAY THEN STALL OVER THE REGION THURSDAY AND FRIDAY BEFORE MOVING OFFSHORE SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 635 AM SUNDAY...BAND OF SHOWERS PASSING SOUTH OF THE CRYSTAL COAST AND THE BULK OF THE ACTIVITY LOOKS TO REMAIN NEAR THE COAST OR OFFSHORE THROUGH MIDDAY AS MID-LEVEL ENERGY HAS PASSED TO OUR NORTHEAST. THE 3 KM HRRR MODEL HAS DONE QUITE WELL WITH THE PLACEMENT OF THE PRECIPITATION THUS FAR THIS MORNING AND PER THE LATEST HRRR WITH AGREEMENT FROM THE RAP...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO REDEVELOP INLAND BY AROUND 18Z AND INCREASE IN COVERAGE THROUGH THE AFTERNOON AND EVENING. POPS RAMP BACK UP TO 30 TO 50 PCT AT THAT TIME WITH THE HIGHEST VALUES OVER AREAS WEST OF HIGHWAY 17. WITH PRECIPITABLE WATER VALUES BACK NEAR 2 INCHES...ANY SHOWERS THAT DEVELOP COULD PRODUCE A QUICK DOWNPOUR OF UP TO AN INCH OR SO. GIVEN MORE CLOUD COVER THAN RECENT DAYS...MAXIMUM TEMPERATURES SHOULD REMAIN IN THE UPPER 80S FAIRLY UNIFORM IN THE MIDDLE TO UPPER 80S AREA-WIDE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... AS OF 345 AM SUNDAY...BOTH THE GFS AND NAM SHOW SOME STRONG MID- LEVEL VORTICITY RIDING UP THE COAST TONIGHT...COUPLED WITH A WEAK UPPER LEVEL TROUGH SLIDING ACROSS THE REGION. THIS ALONG WITH A VERY MOIST ATMOSPHERE WILL LEAD TO A CHANCE OF SHOWERS/TSTMS LINGERING THROUGH THE NIGHT. GIVEN THE TREND FROM THE LAST FEW NIGHTS...HAVE TRENDED THE BEST PRECIPITATION CHANCES NEAR THE COAST...WITH LITTLE ACTIVITY INLAND AFTER MIDNIGHT. OVERNIGHT LOWS TONIGHT SHOULD BE IN THE 73 TO 77 DEGREE RANGE. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 315 AM SUN...AN UPPER TROUGH OVER THE GREAT LAKES WILL DIG SOUTH MON/TUES AND PERSIST OVER THE EASTERN CONUS THROUGH THE LONG TERM...REINFORCING THE RAIN CHANCES THROUGH THE PERIOD. WEAK PERTURBATIONS IN THE MID AND UPPER LEVELS WILL ALSO AID IN DEVELOPING SHOWERS/TSTORMS DURING THE EXTENDED PERIOD...ESPECIALLY DURING PEAK HEATING HOURS OF THE DAY. AT THE SURFACE...LONG FETCH SW FLOW WILL TAP TROPICAL MOISTURE FROM THE GULF OF MEXICO AND WESTERN ATLANTIC MON AND TUES...INCREASING PWATS TO AROUND 2 INCHES. A WEAK COLD FRONT WILL APPROACH FROM THE NW MON INTO TUES...WHICH WILL DISSIPATE WEST OF THE REGION PRIOR TO ANOTHER COLD FRONT APPROACHING FROM THE NW WED INTO THURS. WITH DECENT MODEL AGREEMENT THROUGH THE EXTENDED...HAVE INDICATED A WEAK FRONTAL PASSAGE THURS NIGHT WITH BRIEF NORTHERLY FLOW/CAA ON FRI BEFORE OFFSHORE RIDGE KICKS IN A SW FLOW AGAIN TAKES OVER. HAVE CONTINUED THE TREND OF DIURNAL CONVECTION EACH DAY THROUGH THURS WITH 40 TO 50 PERCENT POPS INLAND DURING THE AFTERNOON AND 25-30 PERCENT POPS OVERNIGHT. TRIED TO ADJUST TIMING OF POPS MON AFTERNOON THROUGH TUES NIGHT TO ALSO COINCIDE WITH THE LOCATION OF SEVERAL SHORTWAVE VORTMAX ALOFT THAT ROTATE AROUND THE BASE OF THE BROAD UPPER TROUGH. SEVERE WEATHER IS NOT EXPECTED AS SHEAR WILL BE MINIMAL...THOUGH WITH ANY PULSE STORM AN ISOLATED STRONG TO SEVERE WIND GUST IS POSSIBLE. WITH OVERALL WEAK STEERING FLOW...ANY ORGANIZED CONVECTION WILL HAVE HEAVY RAINFALL POTENTIAL ESPECIALLY IF CELLS TRAIN OVER THE SAME AREA. POPS THURS NIGHT THROUGH FRI NIGHT REMAIN PINNED NEAR THE COAST WITH SCATTERED CONVECTION POSSIBLE AGAIN SAT AFTERNOON AS LIGHT SE/S FLOW RETURNS TO THE AREA. TEMPS THROUGH THE LONG TERM PERIOD WILL BE NEAR CLIMO WITH HIGHS IN THE UPPER 80S TO NEAR 90 WITH LOW/MID 70S FOR OVERNIGHT LOWS. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... SHORT TERM /TODAY AND TONIGHT/... AS OF 1250 AM SUN...PER LATEST 11-3.9 MICRON SATELLITE IMAGERY AND SURFACE OBSERVATIONS...THERE HAVE BEEN SOME MVFR CEILINGS WELL INLAND AROUND KPGV AND KISO. WITH IMPROVED MIXING...WOULD EXPECT THESE CEILINGS TO DISSIPATE BY 13Z OR 14Z. EXPECT SCATTERED SHOWERS AND TSTMS TO DEVELOP BY AROUND 18Z AND CONTINUE INTO EARLY EVENING WITH A FEW BRIEF REDUCTIONS IN CEILINGS AND VSBY. TONIGHT WILL MOSTLY BE VFR BECAUSE OF SUFFICIENT WIND...BUT SCATTERED SHOWERS AND TSTMS COULD AGAIN BRIEFLY LOWER CEILINGS AND VSBYS. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 315 AM SUN...SCT THUNDERSHOWERS POSSIBLE EACH DAY FOR THE TERMINALS WITH MAINLY DRY CONDITIONS AT NIGHT AS PERSISTENT TROUGH OF LOW PRESSURE REMAINS OVER THE REGION. GENERALLY VFR EXCEPT FOR TEMPO RESTRICTIONS IN VSBY WITH THE SHOWERS/TSTORMS. COULD SEE BRIEF EARLY MORNING MVFR/IFR VSBYS DURING THE LONG TERM AS FORECAST SOUNDINGS INDICATE GOOD BOUNDARY LAYER MOISTURE TRAPPED UNDER A WEAK SURFACE BASED INVERSION...ESPECIALLY FOR AREAS THAT RECEIVE RAINFALL. && .MARINE... SHORT TERM /TODAY AND TONIGHT/... AS OF 645 AM SUNDAY...HAVE ALLOWED THE SMALL CRAFT ADVISORY FOR THE PAMLICO SOUND AND FOR THE COASTAL WATERS NORTH OF OREGON INLET TO EXPIRE. WINDS ARE AT OR BELOW 20 KNOTS IN THESE LOCATIONS. THE REMAINDER OF THE SMALL CRAFT ADVISORY REMAINS IN EFFECT INTO TONIGHT. WINDS ARE CURRENTLY GENERALLY 15 TO 20 KNOTS AND NO BUOY IS REPORTING MORE THAN 5 FEET NEAR SHORE...ALTHOUGH SOME AREAS ON THE OUTER WATERS MAY BE AROUND 6 FEET...THUS THE SCA IS MARGINAL CURRENTLY. HOWEVER...THE GUSTY SW WINDS WILL PERSIST BETWEEN DEEPENING SURFACE TROUGH OVER THE PIEDMONT AND BERMUDA HIGH PRESSURE TO THE EAST AND COULD BECOME GUSTY NEAR ANY CONVECTION DURING THIS AFTERNOON. WINDS AND SEAS SUBSIDE LATER TONIGHT BEFORE INCREASING AGAIN LATE MONDAY...THUS ANOTHER SCA WILL LIKELY NEED TO BE ISSUED ONCE CURRENT ADVISORIES EXPIRE. LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 320 AM SUN...HIGH PRESSURE OFF THE SE COAST WITH A THERMAL TROUGH INLAND WILL BE THE DOMINANT PATTERN THROUGH MUCH OF THE LONG TERM. EXPECT A BREAK IN THE GUSTY SW WINDS MON BEFORE REINFORCING TROUGH/FRONT APPROACH TUES INTO LATE WEEK. MARGINAL SCA CONDITIONS ARE EXPECTED ONCE AGAIN FROM OREGON INLET SOUTH TUES THROUGH TUES NIGHT AS THE GRADIENT INCREASES A BIT. NO SIGNIFICANT CHANGES TO THE MEDIUM AND LONG TERM. WINDS SHOULD BECOME LIGHT LATE IN THE WEEK AS GRADIENT RELAXES WITH TROUGH AXIS OVER OR JUST EAST OF THE WATERS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EDT MONDAY FOR AMZ152-154-156- 158. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...DAG AVIATION...CTC/DAG MARINE...CTC/DAG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
739 AM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 735 AM CDT SUN JUL 21 2013 NO CHANGES NEEDED. LATEST HRRR SHOWS STORM THREAT INTO DVL 23-00Z THEN SPREADING EAST. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 329 AM CDT SUN JUL 21 2013 HIGH PRESSURE OVER NORTHWESTERN ONTARIO EARLY THIS MORNING WITH A A CLEAR TO PARTLY CLOUDY SKY OVER MOST OF THE FCST AREA. EXCEPTIONS ARE AN AREA OF STRATOCU AROUND RUGBY-CANDO NORTHWEST INTO MANITOBA AND EASTERN SASK AND AN AREA OF MID LEVEL CLOUDS OVER NE SD INTO CNTRL-SRN MN. A WEAK SHORT WAVE IS MOVING THRU ECNTRL SD ATTM...CAUSING A FEW SHOWERS IN NE SD MOVING INTO WCNTRL/SW MN JUST SOUTH OF THE FCST AREA. ALL MODELS INDICATE THESE SHOWERS TO CONTINUE GENERALLY SOUTH OF OUR FCST AREA THRU MID MORNING IN A WEAK 850 MB WARM ZONE. MEANWHILE...NO TSTMS OUT IN WRN ND/ERN MT AT 08Z...SO STAGE IS SET FOR A GENERALLY DRY DAY UNTIL A SIGNIFICANT SHORT WAVE MOVES FROM SOUTHERN ALBERTA INTO NRN ND BY 00Z. THIS SHORT WAVE WILL SWING THRU ERN ND TONIGHT INTO NRN MN AFTER 06Z. QUESTION IS TSTM COVERAGE AND INTENSITY WITH SYSTEM. DID LIKE THE SPC 4 KM WRF AND THE NSSL WRF AS THEY BOTH SHOWED REASONABLE SCNERIOS IN THEIR REFLECTIVITY/PRECIP PATTERNS. STORMS IN ALBERTA WILL MOVE INTO SRN SASK AND NW ND MIDDAY AND THEN LOOK FOR INTENSIFICATION AS STORMS MOVE INTO SE SASK/SW MANITOBA AND CNTRL ND MID TO LATE AFTN...WITH AREA OF STORMS MOVING THRU ERN ND 00Z- 03Z REACHING NW MN 03Z-06Z PERIOD. LOOKING AT VARIOUS SEVERE WEATHER FIELDS IT WOULD INDICATE BEST CHC OF SFC BASED SEVERE CONVECTION IN THE MOT-DVL REGION 22Z-00Z PERIOD...THEN MOVING EAST AND INCREASINGLY INSTABILITY BECOMING MORE ELEVATED IN NATURE AND AREA GROWING IN SIZE AS IT MOVE INTO THE NRN/CNTRL RRV TONIGHT. 40 KT LOW LEVEL JET PREDICTED WITH BEST COVERGENCE IN SRN MANITOBA AND THUS MOST WIDESPREAD RAINS LIKELY ALONG OR NORTH OF THE BORDER...BUT MODELS DO TAKE SFC LOW THRU NRN ND SO MORE DISCRETE CELLS PSBL WITH THIS. SRN FCST AREA WHILE NOT CAPPED PER SE HAS A BIT MORE CIN AND LESS COVERAGE OF STORMS. ANY STORMS WILL EXIT MN FCST AREA BY 15Z MON AS HIGH PRESSURE BUILDS IN WITH SOME CLEARING. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 329 AM CDT SUN JUL 21 2013 HIGH PRESSURE WILL GIVE DRY CONDITIONS MON NIGHT INTO TUESDAY...WITH NEXT SHORT WAVE DUE TO ARRIVE LATER TUES NIGHT. GEM APPEARS OVERDONE WITH PRECIP THOUGH. WDNESDAY THROUGH SATURDAY NIGHT...00 UTC GFS/ECMWF BOTH SHOW NORTHWEST FLOW ALOFT...AMPLIFYING BY LATE IN THE WEEK WITH A BUILDING RIDGE ACROSS THE INTERMOUNTAIN WEST AND A LOBE OF THE POLAR VORTEX DIGGING INTO ONTARIO. THIS LATTER FEATURE WILL BE THE PRIMARY FOCUS FOR ANY PRECIPITATION...BUT MODELS DIFFER ON THE TIMING AND LOCATION OF INDIVIDUAL BITS OF ENERGY. THE GFS IS MOST BULLISH WITH PRECIPITATION WEDNESDAY NIGHT THROUGH THURSDAY...WHEREAS THE ECMWF PAINTS THE MOST QPF ACROSS THE REGION FRIDAY NIGHT INTO SATURDAY. POP FORECAST CONFIDENCE IS LOW...SO WILL STICK WITH ALL BLEND 20 TO 30 POPS FOR MUCH OF THE PERIOD. AT THIS TIME...FRIDAY LOOKS TO BE THE DRIEST DAY. FORECAST AREA SHOULD REMAIN ON THE COOL SIDE OF THE MID-LEVEL THERMAL GRADIENT...SO EXPECT TEMPERATURES SLIGHTLY BELOW SEASONAL NORMALS WITH HIGHS IN THE 70S AND LOWS IN THE 50S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 735 AM CDT SUN JUL 21 2013 MAIN ISSUE AVIATION WISE WILL BE TIMING ANY THUNDERSTORM THREATS. GOT SOME VFR STRATOCU ADVANCING NORTHEAST THRU BJI-PKD REGION WITH SCATTERED VFR STRAOCU ELSEWHERE. HIGH CLOUDS SPREADING SOUTHEAST FROM CANADA WILL OVERSPREAD THE AREA THIS MORNING-MIDDAY. LATEST MODEL GUIDANCE INDICATES LOW TO MOVE TOWARD MINOT AROUND 23Z THEN EASTWARD FROM THERE WITH CHC OF TSTMS IN DVL 23Z-03Z...GFK 02-06Z AND THEN AFTER 06Z IN BEMIDJI. THREAT FOR STORMS IN FARGO LOWER AND THUS NOT INCLUDED IN TEMPO GROUP YET. WINDS WILL TURN SOUTH- SOUTHEAST AT 15 KTS IN DVL WITH 5-15 KTS ELSEWHERE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...RIDDLE SHORT TERM...RIDDLE LONG TERM...RIDDLE/ROGERS AVIATION...RIDDLE
AREA FORECAST DISCUSSION...UPDATED
NWS MEMPHIS TN
646 AM CDT SUN JUL 21 2013 .UPDATE... UPDATED FOR AVIATION. && .PREV DISCUSSION... /ISSUED 424 AM CDT SUN JUL 21 2013/ DISCUSSION... A WET WEATHER PATTERN WAS BEGINNING TO TAKE SHAPE ACROSS THE MIDSOUTH THAT WILL LEAD TO SEVERAL DAYS WITH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. BY THURSDAY...MANY LOCATIONS ARE EXPECTED TO HAVE RECEIVED TWO OR THREE OF RAIN...LOCALLY MORE. EARLY THIS MORNING...A NEARLY STATIONARY FRONT STRETCHED TO THE NORTH OF THE MIDSOUTH FROM CENTRAL MO TO SOUTHERN IN. OUTFLOW BOUNDARIES FORMED IN ASSOCIATION WITH THUNDERSTORMS THAT DEVELOPED SOUTH OF THIS FRONT WITH THESE BOUNDARIES PUSHING INTO EAST AR AND NORTHWEST TN LAST EVENING. THIS SPARKED SCATTERED THUNDERSTORMS IN PORTIONS OF THIS REGION DURING THE NIGHT BUT MOST HAVE NOW DISSIPATED. A FEW SHOWERS AND THUNDERSTORMS DEVELOPED EARLY THIS MORNING ACROSS PORTIONS OF NORTHEAST MS DUE TO A WEAK BUT LARGE LOW PRESSURE SYSTEM ALOFT CENTERED ALONG THE NORTHEAST LA / CENTRAL MS BORDER. SEVERAL FACTORS WILL LEAD TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE MIDSOUTH TODAY AND TONIGHT. AN UPPER LEVEL SHORT WAVE WILL PUSH TOWARD THE MIDSOUTH FROM THE NORTHWEST WITH UPPER LEVEL HEIGHTS CONTINUING TO DECREASE TO UNSEASONABLY LOW VALUES ACROSS THE MIDSOUTH. THE UPPER LEVEL LOW TO OUR SOUTH WILL PUSH EAST NORTHEASTWARD TO JUST SOUTH OF NORTHEAST MS. A MOIST AND UNSTABLE ATMOSPHERE WILL EXIST ACROSS THE MIDSOUTH. A FEW STRONG THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND TONIGHT WITH WEAK MID LEVEL LAPSE RATES LIMITING THE THREAT FOR SEVERE THUNDERSTORMS. WINDS GUSTS TO NEAR 50 MPH...SMALL HAIL...AND HEAVY RAINFALL WITH LOCALIZED FLASH FLOODING MAY OCCUR. PRECIPITABLE WATER VALUES WILL INCREASE TO BETWEEN 2 AND 2.25 INCHES ALONG AND WEST OF THE MS RIVER. UPPER LEVEL HEIGHTS WILL CONTINUE TO LOWER ACROSS THE MIDSOUTH TONIGHT AS THE SHORT WAVE EMBEDDED IN A BROAD UPPER LEVEL TROUGH MOVES INTO THE MIDSOUTH RESULTING IN NUMEROUS SHOWERS AND THUNDERSTORMS. ON MONDAY...AN LARGE UPPER LEVEL TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES. MID LEVEL LAPSE RATES WILL DECREASE ACROSS THE MIDSOUTH LEADING TO INCREASED INSTABILITY. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE REGION. THIS WILL PLAY HAVOC WITH HIGH TEMPERATURES SINCE IT IS DIFFICULT TO DETERMINE HOW HOT IT WILL GET BEFORE THE SHOWERS AND STORMS DEVELOP. A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE MONDAY NIGHT AND TUESDAY AS UPPER LEVEL SHORT WAVES EMBEDDED IN NORTHWEST FLOW ALOFT CONTINUE TO INTERACT WITH A MOIST AND UNSTABLE ATMOSPHERE. FOR TUESDAY NIGHT AND WEDNESDAY...THE STORMY WEATHER PATTERN WILL CONTINUE ALTHOUGH THE MODELS ARE NOT IN SYNC WITH THE DETAILS. THE GFS PUSHES A COLD FRONT INTO THE REGION FROM THE NORTH QUICKER THAN THE ECMWF DOES. HOWEVER...THE MODELS DO AGREE THAT A VERY UNSTABLE AND MOIST ATMOSPHERE WILL BE LOCATED OVER THE MIDSOUTH INTO WEDNESDAY. KEPT THURSDAY RAINFREE AS DRIER AIR PUSHES INTO THE REGION FOLLOWING THE PASSAGE OF A WEAK COLD FRONT. FRIDAY LOOKS RAINFREE ALSO WITH A MILD START TO THE DAY BEFORE AFTERNOON TEMPERATURES WARM TO AROUND THE NORMAL VALUES FOR THIS TIME OF THE YEAR. LOOKING AT MODEL FORECAST CHARTS FOR FRIDAY NIGHT AND SATURDAY...YOU WOULD NOT THINK IT WAS JULY. THE MODELS ARE IN FAIRLY GOOD AGREEMENT FOR THAT FAR OUT. ANOTHER BROAD UNSEASONABLY DEEP UPPER LEVEL TROUGH WILL DIG ALONG THE EASTERN UNITED STATES. THE GFS INDICATES A 1010 MB LOW NEAR THE MO BOOTHEEL 7 AM SATURDAY WITH A COLD FRONT TRAILING TO THE SOUTHWEST WHILE THE ECMWF IS A LITTLE SLOWER AND STRONGER INDICATING A 1006 MB LOW OVER SOUTH CENTRAL MO WITH A TRAILING COLD FRONT TO THE SOUTHWEST. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL OCCUR AHEAD OF THIS SYSTEM FRIDAY NIGHT AND SATURDAY. COOLER AND DRY HIGH PRESSURE IS FORECAST TO BEHIND INTO THE REGION FROM THE NORTH WITH PASSAGE OF THE LOW PRESSURE SYSTEM AND COLD FRONT. JCL && .AVIATION... 12Z TAFS PRIMARY FORECAST CONCERN REMAINS TIMING AND LOCATION OF TSRA ONSET. TSRA CHANCES WILL INCREASE AT ALL LOCATIONS AFTER 15Z. PRESENCE OF ISOLATED SHRA/TSRA EARLY THIS MORNING INDICATES SOME ELEVATED INSTABILITY...BUT THIS ACTIVITY HAS FAILED TO ORGANIZE FOR ANY APPRECIABLE LENGTH OF TIME. FOR THE 12Z TAFS...HAVE NARROWED TEMPOS DOWN TO NEAR PEAK HEATING WITH RESPECT TO TSRA TIMING. OF CONCERN IS UPPER LEVEL LOW OVER NORTHEAST LA...WHICH COULD HELP INITIATE TSRA BY LATE MORNING. GFS LAMP GUIDANCE AND HRRR MODELS SHOWED LITTLE EFFECT OF THIS UPPER LEVEL FEATURE FOR THE MORNING HOURS. BUT WILL SKIES TO START THE DAY... AMPLE SURFACE HEATING OVER THE ARKLAMISS MAY TOUCH OFF MID/LATE MORNING TSRA POSSIBLY EXTENDING UP TOWARD MEM. PWB && .PRELIMINARY POINT TEMPS/POPS... MEM 93 74 91 75 / 50 60 60 50 MKL 90 71 89 72 / 50 60 60 50 JBR 92 72 91 73 / 60 60 60 50 TUP 92 73 90 73 / 50 60 60 50 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
622 AM CDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 300 AM CDT SUN JUL 21 2013 CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS LOOKED VERY SIMILAR TO THIS TIME YESTERDAY...CONSISTING OF NORTHWEST FLOW FROM BRITISH COLUMBIA INTO THE GREAT LAKES REGION...NUMEROUS SHORTWAVES RIDING THROUGH THE FLOW...AND TROUGHING OVER SOUTHEAST CANADA. MOST OF THE SHORTWAVES ARE WEAK EXCEPT FOR A MORE IMPRESSIVE ONE OVER CENTRAL ALBERTA. THE MAIN SHORTWAVE OF INTEREST IN THE SHORT TERM IS ORIGINATING OUT OF CONVECTION OVER SOUTHEAST SD AND EASTERN NEBRASKA. AIRMASS OVER THE FORECAST AREA VARIES GREATLY FROM SOUTH TO NORTH WITH I-94 BEING A GREAT DIVIDING LINE. TO THE NORTH...DRIER AIR CHARACTERIZED BY SURFACE DEWPOINTS IN THE 40S AND LOW 50S WAS PRESENT. FARTHER UP TO THE NORTH...THE 00Z INL SOUNDING REPORTED A PRECIPITABLE WATER VALUE OF 0.49 INCHES. NOW...SOUTH AND WEST OF I-94...DEWPOINTS ARE IN THE 60S. THE 00Z SOUNDINGS FROM MPX AND DVN HAD PRECIPITABLE WATER VALUES AROUND 1.15 INCHES. SEPARATING THESE TWO AIRMASSES IS A STATIONARY FRONTAL BOUNDARY. ISOLATED SHOWERS/STORMS HAVE BEEN POPPING UP ALONG/NORTH OF THE BOUNDARY ALL NIGHT. SYNOPTIC OVERVIEW... NORTHWEST FLOW CONTINUES THROUGH THE SHORT TERM PERIOD. THE CONVECTIVELY INDUCED SHORTWAVE TROUGH APPROACHING SIOUX CITY IA AT 08Z MODELS ARE STRUGGLING WITH GREATLY. MOST MODELS...INCLUDING HI RESOLUTION RUNS SUCH AS THE HRRR AND HIRES-ARW ARE TOO SLOW. EXTRAPOLATION HAS THE MCV CROSSING MUCH OF IOWA THIS MORNING. POTENTIAL THEN EXISTS FOR SOME VERY WEAK RIDGING IN ITS WAKE FOR THIS AFTERNOON AND TONIGHT...AHEAD OF THE CURRENT ALBERTA SHORTWAVE WHICH DIGS INTO NORTHERN MN AND WESTERN ONTARIO BY 12Z MONDAY. TODAY... DESPITE THIS PERIOD BEING THE BEGINNING OF THE FORECAST...THE UNCERTAINTY IS QUITE HIGH. MUCH OF THIS UNCERTAINTY STEMS FROM THE TOO SLOW HANDLING FROM ALL MODELS REGARDING THE MCV APPROACHING SIOUX CITY IA AS OF 08Z. GENERALLY FOLLOWED AN EXTRAPOLATION APPROACH COMBINED WITH A SOMEWHAT SPED UP 21.05Z HRRR FORECAST TO COME UP WITH THE FORECAST TODAY. THE PLAN IS THAT THE MCV SHOULD TRACK ACROSS DES MOINES AND DAVENPORT THIS MORNING...WITH THE FORECAST AREA ON THE NORTH SIDE. SHOWERS AND A FEW EMBEDDED THUNDERSTORMS APPEAR LIKELY...PRIMARILY WEST OF THE MISSISSIPPI RIVER DURING THE MORNING HOURS. CONCERNED THAT THE DIURNAL EFFECTS ON LOW LEVEL MOISTURE TRANSPORT MAY CAUSE THE SHOWERS TO WEAKEN SOME AS WE APPROACH MID-DAY...THUS THE HIGHER CHANCES TO THE WEST. DURING THE AFTERNOON...IT IS HARD TO SAY WHATS GOING TO OCCUR. WE COULD EASILY BE IN SUBSIDENCE IN THE WAKE OF THE MCV...PREVENTING MUCH IN THE WAY OF ADDITIONAL PRECIPITATION. ON THE OTHER HAND...THE AFTERNOON IS PEAK HEATING AND WITH HIGHER DEWPOINTS TODAY...WE SHOULD BE ABLE TO BUILD 500-1500 J/KG OF CAPE AS SUGGESTED BY THE RAP. ANY SHORTWAVE COMING THROUGH THE NORTHWEST FLOW THATS HARD TO DISCERN AT THIS TIME COULD KICK OFF SHOWERS AND STORMS. ADDITIONALLY WE SHOULD STILL HAVE THAT STATIONARY FRONTAL BOUNDARY IN THE FORECAST AREA TO PROVIDE WEAK LOW LEVEL CONVERGENCE. THEREFORE... HAVE MAINTAINED AT LEAST 40-50 PERCENT CHANCES FOR THE AFTERNOON. REGARDING TEMPERATURES...ASSUMING SOME SUN TODAY WHICH SHOULD OCCUR...925MB TEMPS IN THE 18-20C RANGE SUPPORTS HIGHS IN THE 70S TO NEAR 80. TONIGHT... ANY CONVECTION THAT OCCURS THIS AFTERNOON WILL LIKELY HAVE A STRONG DIURNAL COMPONENT TO IT. THEREFORE...HAVE PRECIPITATION CHANCES DIMINISHING THROUGH THE EVENING HOURS. HOWEVER...850MB MOISTURE TRANSPORT DOES INCREASE THROUGH THE NIGHT AHEAD OF THE STRONGER SHORTWAVE DROPPING INTO NORTHERN MN. CONVECTION WILL LIKELY FORM ON THE NOSE OF THIS MOISTURE TRANSPORT...WHICH IS FORECAST FROM NORTHERN MN INTO NORTHERN WI. KEPT SOME 20 PERCENT CHANCES OVERNIGHT BOTH OVER TAYLOR/CLARK COUNTIES FOR THE NOSE OF THIS MOISTURE TRANSPORT. ALSO KEPT THE 20 PERCENT CHANCES OVERNIGHT FOR THE EASTERN HALF OF THE FORECAST AREA...IN THE EVENT ANY DIURNAL CONVECTION CAN SURVIVE...THOUGH AS THE CHANCE STATES THE CONFIDENCE IS LOW. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 300 AM CDT SUN JUL 21 2013 SYNOPTIC OVERVIEW... 20.00Z ECMWF/GFS/CANADIAN ALL CONTINUE THE NORTHWEST FLOW PATTERN THROUGH THE ENTIRE LONG TERM PERIOD. WHAT LOOKED TO BE A POSSIBILITY OF RIDGING BUILDING TOWARDS THE AREA BRIEFLY THURSDAY INTO FRIDAY IS NOW COMPLETELY GONE. PART OF THE REASON WE STAY IN NORTHWEST FLOW IS THE DEVELOPMENT OF AN OMEGA BLOCK OVER WESTERN CANADA BETWEEN TUESDAY AND WEDNESDAY...WHICH DOES NOT SHOW ANY SIGNS OF BREAKING DOWN FOR AWHILE. ADDITIONALLY...THERE APPEARS TO BE SOME MODEL STRUGGLES HANDLING SHORTWAVE TROUGHING COMING DOWN THE EAST SIDE OF THE OMEGA BLOCK...WHICH PUTS MORE UNCERTAINTY FOR THE FORECAST THURSDAY AND BEYOND. ONE THING THAT IS STARTING TO BECOME A LITTLE MORE EVIDENT IS FOR DEEPER TROUGHING OVER THE GREAT LAKES REGION AT THE END OF NEXT WEEKEND. 500MB STANDARDIZED ANOMALIES FOR 12Z SUNDAY FROM THE ECMWF/GFS ARE 1.5-2 BELOW NORMAL. HAZARDS... THERE COULD BE SOME ISOLATED SEVERE WEATHER LATE MONDAY AFTERNOON INTO THE EVENING HOURS...ASSOCIATED WITH A COLD FRONT COMING THROUGH...BUT CONFIDENCE IS LOW AS DESCRIBED BELOW. MONDAY THROUGH TUESDAY NIGHT... MUCH OF THE FOCUS HERE IS ON THE MONDAY/MONDAY NIGHT PERIOD. SHORTWAVE TROUGH OVER NORTHERN MN AND WESTERN ONTARIO AT 12Z MONDAY MODELS ALL AGREE ON SLIDING IT ACROSS NORTHERN ONTARIO. AS THIS OCCURS...A COLD FRONT ASSOCIATED WITH IT APPROACHES THE FORECAST AREA. TIMING ON THIS FRONT VARIES GREATLY. AT 00Z TUESDAY...TIMING VARIES FROM THE 21.00Z HIRES-ARW HAVING IT WEST OF MINNEAPOLIS TO THE 21.00Z ECMWF/GFS OVER MINNEAPOLIS AND THE 21.00Z CANADIAN/NAM/UKMET WHICH ARE OVER LA CROSSE. TRENDS AT LEAST FROM THE ECMWF/GFS SUGGEST A SLOWER APPROACH MAY BE THE WAY TO GO. THERE STILL REMAINS UNCERTAINTY ON CONVECTIVE CHANCES WITH THIS FRONT... 1. A WARM SURGE OF AIR AT 800MB IS STILL INDICATED TO COME OVER THE FRONT TO PROVIDING POTENTIAL CAPPING 2. THE SHORTWAVE TROUGH SLIDING ACROSS NORTHERN ONTARIO COULD END UP PUTTING RIDGING OVER THE FRONT FOR THE AFTERNOON AS SUGGESTED BY THE 21.00Z HIRES-ARW. 3. LOW LEVEL CONVERGENCE ON THE FRONT REMAINS IN QUESTION. 4. NOW THE FRONT BEING SLOWER...NOT COMING ACROSS THE FORECAST AREA AT PEAK HEATING...COULD BE A NEGATIVE FOR PRECIP. TO ACCOUNT FOR THE SLOWER TREND HAVE LOWERED PRECIPITATION CHANCES SOME MONDAY AFTERNOON. LEFT THE 40-60 PERCENT CHANCES FOR MONDAY EVENING AS THAT IS STILL FAIRLY WELL AGREED UPON BY GUIDANCE...THEN CHANCES DIMINISHING AFTER MIDNIGHT WITH LOSS OF HEATING AND THE FRONT PROGRESSING THROUGH THE AREA. DRY WEATHER FOLLOWS IN THE WAKE OF THE FRONT FOR TUESDAY AND TUESDAY NIGHT WHILE HIGH PRESSURE BUILDS IN AT THE SURFACE. 925MB TEMPS CLIMBING TO 21-24C AHEAD OF THE FRONT ON MONDAY PLUS SUNSHINE WILL ALLOW HIGHS TO CLIMB INTO THE 80S. MAY EVEN SEE 90 IN A FEW SPOTS IF MORE SUN OCCURS. MONDAY LOOKS HUMID AS WELL AS NEAR 70 DEGREE DEWPOINTS ADVECT IN AT THE SURFACE. COOLER HIGHS ON THE WAY FOR TUESDAY AS 925MB TEMPS TUMBLE TO 17-20C. TUESDAY NIGHT LOWS HAVE POTENTIAL TO GET INTO THE 40S AT THE TYPICAL COLDER SPOTS...DUE TO LIGHT WINDS AND PRECIPITABLE WATER VALUES FALLING TO 0.5-0.75 INCHES. WEDNESDAY THROUGH SATURDAY NIGHT... 20.00Z ECMWF/GFS/CANADIAN ARE SUGGESTING NUMEROUS WEAK SHORTWAVES DROP SOUTHEAST ACROSS THE FORECAST AREA WEDNESDAY THROUGH THURSDAY IN THE NORTHWEST FLOW ALOFT. HARD TO SAY IF ANY OF THESE ARE GOING TO DO ANYTHING PRECIP WISE. 20.00Z CANADIAN AND 19.12Z ECMWF WANT TO BRING SOME SHOWERS ACROSS WEDNESDAY NIGHT AND THURSDAY...THOUGH THE 20.00Z ECMWF BACKED OFF. WOULD THINK A DRIER SCENARIO IS MORE LIKELY GIVEN THE DRY AIRMASS COMING IN TUESDAY NIGHT/WEDNESDAY WITH CANADIAN HIGH PRESSURE IN PLACE. NEVERTHELESS...DID HONOR A 20 PERCENT CHANCE MAINLY ON THURSDAY JUST IN CASE. CHANCES INCREASE A LITTLE FOR THURSDAY NIGHT AND FRIDAY WHERE IT APPEARS A COLD FRONT WILL CROSS THE AREA...ASSOCIATED WITH A POTENT UPPER TROUGH DROPPING OVER MANITOBA AND NORTHERN ONTARIO. SOME OF THIS UPPER TROUGH LOOKS TO SWING ACROSS THE FORECAST AREA FRIDAY NIGHT AND SATURDAY...THUS STILL NEED TO CONTINUE AT LEAST 20 PERCENT CHANCES. BEING IN THIS NORTHWEST FLOW PATTERN COMBINED WITH EVEN DEEPER TROUGHING FORMING OVER THE WEEKEND SUGGESTS BELOW NORMAL TEMPERATURES. BY 12Z SUNDAY...BOTH THE 20.00Z ECMWF AND GFS DEPICT 850MB TEMPS FALLING TO 6-9C...CHILLY RELATIVELY SPEAKING FOR THE END OF JULY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 622 AM CDT SUN JUL 21 2013 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL IMPACT THE TAF SITES FROM LATE THIS MORNING THROUGH THIS AFTERNOON. MVFR STRATUS HAS DEVELOPED ACROSS PORTIONS OF SOUTHWEST WISCONSIN...NEAR THE MISSISSIPPI RIVER...AND IS JUST EDGING INTO KLSE. PLAN ON THE MVFR STRATUS TO LINGER THROUGH 14Z THIS MORNING WITH CLOUD BASES AROUND 1500 FT. A WARM FRONT SITUATED NEAR THE INTERSTATE 90 CORRIDOR WILL GRADUALLY LIFT NORTH THIS AFTERNOON INTO THIS EVENING WITH MOIST SOUTHERLY FLOW SETTING UP OVER THE REGION IN THE WAKE OF THE FRONT. WILL HAVE TO KEEP A CLOSE WATCH ON THE POTENTIAL FOR SOME IFR/MVFR STRATUS TONIGHT AND AREAS OF BR. CURRENT THINKING IS THAT THERE WILL BE ENOUGH MIXING TONIGHT TO INHIBIT THE DEVELOPMENT OF THE LOW STRATUS. THERE SHOULD BE A BREAK IN THE SHOWER AND THUNDERSTORM ACTIVITY LATE THIS EVENING INTO EARLY MONDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
935 AM MST SUN JUL 21 2013 .UPDATE...UPDATED AVIATION DISCUSSION... ...POTENTIAL FOR HEAVY RAINFALL TODAY... .SYNOPSIS... A LOW PRESSURE SYSTEM IN MEXICO WILL CONTINUE TO SUPPLY MOISTURE TO THE DESERT SOUTHWEST TODAY. HUMID CONDITIONS WILL RESULT IN WELL-ABOVE NORMAL RAIN CHANCES AND WELL-BELOW NORMAL TEMPERATURES. A DRYING TREND WILL BEGIN MONDAY...CONTINUING INTO WEDNESDAY AS HIGH PRESSURE BUILDS BACK OVER THE REGION. MONSOON MOISTURE MOVING BACK NORTHWARD INTO THE REGION IS LIKELY TO ONCE AGAIN INCREASE RAIN CHANCES FOR THE END OF THE WEEK AND INTO THE WEEKEND. && .DISCUSSION... A VERY MOIST AIRMASS IN PLACE IN COMBINATION WITH BROAD UPPER DIFLUENCE ALOFT CENTERED OVER WESTERN ARIZONA IS CREATING A WET MORNING ACROSS MUCH OF SOUTHWEST AZ AND AREAS ELSEWHERE. A UNSEASONABLY STRONG UPPER LOW CENTERED JUST OFF THE WEST COAST OF BAJA AND A FLATTENED UPPER RIDGE STRETCHING FROM NORTHERN CA INTO CO HAS RESULTED IN MODEST DIFLUENCE ALOFT. AN OVERNIGHT MCS THAT DEVELOPED ACROSS SOUTHERN AZ ON THE NORTHERN PERIPHERY OF THE UPPER LOW CONTINUES TO TRACK NORTHWESTWARD ACROSS WESTERN MARICOPA AND YUMA COUNTIES. WITH PWATS OF AROUND 2 INCHES...RAINFALL RATES HAVE BEEN VERY IMPRESSIVE WITH THE STRONGEST THUNDERSTORMS. THE AUTOMATED RAIN GAGE AT THE BENDER WASH JUST EAST OF GILA BEND REPORTED 2.24 INCHES OF RAIN IN AROUND 45 MINUTES. OTHER GAGES HAVE REPORTED LESS THAN AN INCH OF RAINFALL...BUT RADAR ESTIMATES INDICATE SOME RURAL AREAS OF EASTERN YUMA AND WESTERN MARICOPA COUNTIES HAVE RECEIVED 1 TO 2 INCHES OF RAINFALL SINCE 5 AM THIS MORNING. HEAVY RAINFALL AND THE FLASH FLOOD POTENTIAL WILL BE THE MAIN AND NEARLY THE ONLY THREAT TODAY. THE 12Z SOUNDING AT KPHX AND FORECAST SOUNDINGS SHOW AN EXTREMELY MOIST PROFILE WITH NO SIGNIFICANT DRY LAYERS ALOFT. CAN/T RULE OUT SOME STRONG WIND GUSTS ASSOCIATED WITH A WET MICROBURST WITH THE STRONGEST STORMS TODAY...BUT GUSTS WILL MOST DEFINITELY BE SUB-SEVERE. LATEST HRRR AND LOCAL WRF RUNS SHOW A MIXED PICTURE FOR STORM ACTIVITY FOR THE REST OF TODAY. THE MCS SHOULD CONTINUE IT/S TRACK NORTHWESTWARD LATE THIS MORNING INTO THE EARLY AFTERNOON BEFORE EITHER DISSIPATING OR MOVING OUT OF THE CWA. ADDITIONAL ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG AND JUST TO THE EAST OF THE MCS OVER CENTRAL MARICOPA COUNTY SINCE 8 AM MST. CURRENT SATELLITE IMAGERY AND OBJECTIVE ANALYSIS SHOWS MORE UNSTABLE AIR WITH MIXED LAYER CAPES OF AROUND 1000 J/KG OVER SOUTH-CENTRAL AND SOUTHEAST AZ. GIVEN THE SURFACE DEW POINTS IN THE LOWER 70S ACROSS THIS AREA...SHOULD SEE REDEVELOPMENT OF STORMS EVEN BEFORE NOON TODAY AND MORE LIKELY THROUGHOUT THE AFTERNOON HOURS. THESE STORMS WILL LIKELY CONTINUE TO TRACK WESTWARD INTO PORTIONS OF SOUTHWEST AZ AND SOUTHEAST CA THIS EVENING AND POSSIBLY DURING THE OVERNIGHT HOURS TONIGHT. THE FLASH FLOOD THREAT SHOULD BE ISOLATED DUE TO THE FAIRLY WORKED OVER ATMOSPHERE FROM THE PAST 24 HOURS...SO NO FLASH FLOOD WATCHES ARE EXPECTED AT THIS TIME. && .PREVIOUS DISCUSSION... UPPER LOW CONTINUES TO SPIN WESTWARD INTO THE PACIFIC OCEAN JUST OFF THE BAJA PENINSULA. FURTHER NORTH...THE MID-TROPOSPHERIC ANTICYCLONE REMAINS POSITIONED ACROSS CA/NV. RESULTING MID-LEVEL EASTERLY FLOW IS STRONGER THAN NORMAL (STANDARDIZED ANOMALY NEAR 1.0) AND CONTINUES TO ADVECT DEEP SUB-TROPICAL MOISTURE INTO THE FORECAST AREA. SURFACE DEWPOINTS ARE CURRENTLY IN THE LOWER 70S ACROSS THE PHOENIX METRO AREA WHILE THE GPS-IPW REGISTERED AROUND 1.75 INCHES...WELL ABOVE NORMAL. LATEST RAP INDICATES THAT PWATS MAY BE AS HIGH AS 2.0 TO 2.4 INCHES ACROSS THE SOUTHWEST DESERTS AND TOWARDS PUERTO PENASCO. LATEST WV IMAGERY SHOWS TWO MCS...ONE ACROSS THE MOJAVE DESERT AND THE OTHER ACROSS SOUTHERN AZ...BEARING DOWN ON SW AZ AND SE CA. STRONG LOW-LEVEL CONVERGENCE IS EXPECTED EARLY THIS MORNING AND POPS WERE INCREASED IN THESE AREAS. ACROSS SOUTH-CENTRAL AZ...NMM AND WRF-BASED GUIDANCE CONTINUES TO SUGGEST THAT SHOWERS WILL REDEVELOP AS EARLY AS THIS MORNING. THIS SEEMS REASONABLE GIVEN THE AMPLE MOISTURE AND IT WILL ONLY TAKE A MINIMAL AMOUNT OF HEATING FOR CONVECTION TO INITIATE. MODELS ALSO SUGGEST THAT VORTICITY-FORCED ASCENT WILL AID IN THE DEVELOPMENT OF STORMS THIS AFTERNOON ACROSS SE CA. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN AND LOCALIZED FLOODING. THE COPIOUS AMOUNT OF MOISTURE WILL ALSO RESULT IN CONSIDERABLE CLOUDINESS ACROSS MUCH OF THE AREA...WHICH WILL KEEP TEMPERATURES WELL BELOW NORMAL. FORECAST HIGH FOR PHOENIX IS 95 DEGREES. A MAX TEMP THIS LOW HAS NOT OCCURRED SINCE MAY 27. A SIGNIFICANT DRYING TREND WILL TAKE PLACE MONDAY AS THE UPPER LOW LIFTS STEADILY NORTHWARD. SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...THOUGH COVERAGE WILL BE NOTICEABLY LESS THAN WHAT HAS OCCURRED THE PAST FEW DAYS. THE UPPER LOW WILL BE PICKED UP BY THE WESTERLIES TUESDAY AS THE MONSOON HIGH BECOMES REPOSITIONED ACROSS THE ROCKIES. GFS/ECMWF DIFFER ON THE AMOUNT OF MOISTURE LEFT OVER ACROSS THE DESERT SOUTHWEST THOUGH THE CONSENSUS IS THAT IT SHOULD BE SUFFICIENT FOR ISOLATED THUNDERSTORMS THROUGH THE WEEK. FLOW WILL BE WEAK AS AN ANTICYCLONE BUILDS BACK ACROSS AZ AND CONVECTION WILL MAINLY BE RELEGATED TO THE HIGHER TERRAIN. A WARMING TREND IS ALSO EXPECTED WITH A RETURN TO ABOVE NORMAL TEMPERATURES BY THURSDAY. MODELS ARE IN GENERALLY GOOD AGREEMENT THAT ANOTHER PVD WILL SLIDE WESTWARD THROUGH SONORA LATE IN THE WEEK...RESULTING IN AN INFLUX OF MOISTURE. FORECAST IS FOR BELOW CLIMO POPS THROUGH MIDWEEK...FOLLOWED BY NEAR CLIMO POPS THURSDAY THROUGH SUNDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... THUNDERSTORMS ARE NOW DEVELOPING...AND MOVING NORTHWARD ACROSS THE GREATER PHOENIX AREA. THESE STORMS ARE EXPECTED TO AFFECT THE TERMINALS OVER THE NEXT COUPLE OF HOURS BEFORE SOMEWHAT DRIER AIR MOVING IN FROM THE SOUTH REDUCES ACTIVITY THIS AFTERNOON AND EVENING. GENERALLY LIGHT WINDS AND SCT-BKN CLOUD DECKS AOA 6-8KFT ARE EXPECTED WITH PERIODS OF CIGS LOWERING TO 3-4KFT/VISIBILITIES REDUCED DOWN TO 4SM IN HEAVIER SHOWERS AND THUNDERSTORMS. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... ISOLATED SHOWER/THUNDERSTORM ACTIVITY WILL CONTINUE TO FILL IN OVER SOUTHEAST CALIFORNIA THIS MORNING THROUGH AT LEAST 17Z...WITH GUSTY OUTFLOWS TO 30KT POSSIBLE AT TIMES...ESPECIALLY NEAR KNYL. SCT-BKN CLOUD DECKS WITH CIGS DOWN TO AROUND 6-8KFT IN HEAVIER SHOWERS AND THUNDERSTORMS WITH SKIES/CIGS IMPROVING LATER THIS AFTERNOON. WINDS S-SELY AROUND 10-15KT THROUGH MUCH OF THE TAF PERIOD ACROSS THE LOWER COLORADO RIVER VALLEY/KBLH WITH LIGHTER SELY WINDS AT KIPL. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... A SWITCH TO A SOUTHERLY FLOW ALOFT WILL BRING DRYING CONDITIONS AND ENDING PRECIPITATION CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. SLIGHT CHANCES FOR STORMS WILL CONTINUE ACROSS SOUTH-CENTRAL ARIZONA WITH BETTER CHANCES ACROSS HIGHER TERRAIN LOCATIONS NORTH AND EAST OF PHOENIX. HUMIDITIES WILL REMAIN ELEVATED THROUGH THE ENTIRE PERIOD WITH AFTERNOON HUMIDITIES ONLY DROPPING INTO THE 20-30 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...KUHLMAN PREVIOUS DISCUSSION...HIRSCH AVIATION...PERCHA/MEYERS FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
923 AM MST SUN JUL 21 2013 ...POTENTIAL FOR HEAVY RAINFALL TODAY... .SYNOPSIS... A LOW PRESSURE SYSTEM IN MEXICO WILL CONTINUE TO SUPPLY MOISTURE TO THE DESERT SOUTHWEST TODAY. HUMID CONDITIONS WILL RESULT IN WELL-ABOVE NORMAL RAIN CHANCES AND WELL-BELOW NORMAL TEMPERATURES. A DRYING TREND WILL BEGIN MONDAY...CONTINUING INTO WEDNESDAY AS HIGH PRESSURE BUILDS BACK OVER THE REGION. MONSOON MOISTURE MOVING BACK NORTHWARD INTO THE REGION IS LIKELY TO ONCE AGAIN INCREASE RAIN CHANCES FOR THE END OF THE WEEK AND INTO THE WEEKEND. && .DISCUSSION... A VERY MOIST AIRMASS IN PLACE IN COMBINATION WITH BROAD UPPER DIFLUENCE ALOFT CENTERED OVER WESTERN ARIZONA IS CREATING A WET MORNING ACROSS MUCH OF SOUTHWEST AZ AND AREAS ELSEWHERE. A UNSEASONABLY STRONG UPPER LOW CENTERED JUST OFF THE WEST COAST OF BAJA AND A FLATTENED UPPER RIDGE STRETCHING FROM NORTHERN CA INTO CO HAS RESULTED IN MODEST DIFLUENCE ALOFT. AN OVERNIGHT MCS THAT DEVELOPED ACROSS SOUTHERN AZ ON THE NORTHERN PERIPHERY OF THE UPPER LOW CONTINUES TO TRACK NORTHWESTWARD ACROSS WESTERN MARICOPA AND YUMA COUNTIES. WITH PWATS OF AROUND 2 INCHES...RAINFALL RATES HAVE BEEN VERY IMPRESSIVE WITH THE STRONGEST THUNDERSTORMS. THE AUTOMATED RAIN GAGE AT THE BENDER WASH JUST EAST OF GILA BEND REPORTED 2.24 INCHES OF RAIN IN AROUND 45 MINUTES. OTHER GAGES HAVE REPORTED LESS THAN AN INCH OF RAINFALL...BUT RADAR ESTIMATES INDICATE SOME RURAL AREAS OF EASTERN YUMA AND WESTERN MARICOPA COUNTIES HAVE RECEIVED 1 TO 2 INCHES OF RAINFALL SINCE 5 AM THIS MORNING. HEAVY RAINFALL AND THE FLASH FLOOD POTENTIAL WILL BE THE MAIN AND NEARLY THE ONLY THREAT TODAY. THE 12Z SOUNDING AT KPHX AND FORECAST SOUNDINGS SHOW AN EXTREMELY MOIST PROFILE WITH NO SIGNIFICANT DRY LAYERS ALOFT. CAN/T RULE OUT SOME STRONG WIND GUSTS ASSOCIATED WITH A WET MICROBURST WITH THE STRONGEST STORMS TODAY...BUT GUSTS WILL MOST DEFINITELY BE SUB-SEVERE. LATEST HRRR AND LOCAL WRF RUNS SHOW A MIXED PICTURE FOR STORM ACTIVITY FOR THE REST OF TODAY. THE MCS SHOULD CONTINUE IT/S TRACK NORTHWESTWARD LATE THIS MORNING INTO THE EARLY AFTERNOON BEFORE EITHER DISSIPATING OR MOVING OUT OF THE CWA. ADDITIONAL ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG AND JUST TO THE EAST OF THE MCS OVER CENTRAL MARICOPA COUNTY SINCE 8 AM MST. CURRENT SATELLITE IMAGERY AND OBJECTIVE ANALYSIS SHOWS MORE UNSTABLE AIR WITH MIXED LAYER CAPES OF AROUND 1000 J/KG OVER SOUTH-CENTRAL AND SOUTHEAST AZ. GIVEN THE SURFACE DEW POINTS IN THE LOWER 70S ACROSS THIS AREA...SHOULD SEE REDEVELOPMENT OF STORMS EVEN BEFORE NOON TODAY AND MORE LIKELY THROUGHOUT THE AFTERNOON HOURS. THESE STORMS WILL LIKELY CONTINUE TO TRACK WESTWARD INTO PORTIONS OF SOUTHWEST AZ AND SOUTHEAST CA THIS EVENING AND POSSIBLY DURING THE OVERNIGHT HOURS TONIGHT. THE FLASH FLOOD THREAT SHOULD BE ISOLATED DUE TO THE FAIRLY WORKED OVER ATMOSPHERE FROM THE PAST 24 HOURS...SO NO FLASH FLOOD WATCHES ARE EXPECTED AT THIS TIME. && .PREVIOUS DISCUSSION... UPPER LOW CONTINUES TO SPIN WESTWARD INTO THE PACIFIC OCEAN JUST OFF THE BAJA PENINSULA. FURTHER NORTH...THE MID-TROPOSPHERIC ANTICYCLONE REMAINS POSITIONED ACROSS CA/NV. RESULTING MID-LEVEL EASTERLY FLOW IS STRONGER THAN NORMAL (STANDARDIZED ANOMALY NEAR 1.0) AND CONTINUES TO ADVECT DEEP SUB-TROPICAL MOISTURE INTO THE FORECAST AREA. SURFACE DEWPOINTS ARE CURRENTLY IN THE LOWER 70S ACROSS THE PHOENIX METRO AREA WHILE THE GPS-IPW REGISTERED AROUND 1.75 INCHES...WELL ABOVE NORMAL. LATEST RAP INDICATES THAT PWATS MAY BE AS HIGH AS 2.0 TO 2.4 INCHES ACROSS THE SOUTHWEST DESERTS AND TOWARDS PUERTO PENASCO. LATEST WV IMAGERY SHOWS TWO MCS...ONE ACROSS THE MOJAVE DESERT AND THE OTHER ACROSS SOUTHERN AZ...BEARING DOWN ON SW AZ AND SE CA. STRONG LOW-LEVEL CONVERGENCE IS EXPECTED EARLY THIS MORNING AND POPS WERE INCREASED IN THESE AREAS. ACROSS SOUTH-CENTRAL AZ...NMM AND WRF-BASED GUIDANCE CONTINUES TO SUGGEST THAT SHOWERS WILL REDEVELOP AS EARLY AS THIS MORNING. THIS SEEMS REASONABLE GIVEN THE AMPLE MOISTURE AND IT WILL ONLY TAKE A MINIMAL AMOUNT OF HEATING FOR CONVECTION TO INITIATE. MODELS ALSO SUGGEST THAT VORTICITY-FORCED ASCENT WILL AID IN THE DEVELOPMENT OF STORMS THIS AFTERNOON ACROSS SE CA. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAIN AND LOCALIZED FLOODING. THE COPIOUS AMOUNT OF MOISTURE WILL ALSO RESULT IN CONSIDERABLE CLOUDINESS ACROSS MUCH OF THE AREA...WHICH WILL KEEP TEMPERATURES WELL BELOW NORMAL. FORECAST HIGH FOR PHOENIX IS 95 DEGREES. A MAX TEMP THIS LOW HAS NOT OCCURRED SINCE MAY 27. A SIGNIFICANT DRYING TREND WILL TAKE PLACE MONDAY AS THE UPPER LOW LIFTS STEADILY NORTHWARD. SHOWERS AND THUNDERSTORMS ARE STILL ANTICIPATED...THOUGH COVERAGE WILL BE NOTICEABLY LESS THAN WHAT HAS OCCURRED THE PAST FEW DAYS. THE UPPER LOW WILL BE PICKED UP BY THE WESTERLIES TUESDAY AS THE MONSOON HIGH BECOMES REPOSITIONED ACROSS THE ROCKIES. GFS/ECMWF DIFFER ON THE AMOUNT OF MOISTURE LEFT OVER ACROSS THE DESERT SOUTHWEST THOUGH THE CONSENSUS IS THAT IT SHOULD BE SUFFICIENT FOR ISOLATED THUNDERSTORMS THROUGH THE WEEK. FLOW WILL BE WEAK AS AN ANTICYCLONE BUILDS BACK ACROSS AZ AND CONVECTION WILL MAINLY BE RELEGATED TO THE HIGHER TERRAIN. A WARMING TREND IS ALSO EXPECTED WITH A RETURN TO ABOVE NORMAL TEMPERATURES BY THURSDAY. MODELS ARE IN GENERALLY GOOD AGREEMENT THAT ANOTHER PVD WILL SLIDE WESTWARD THROUGH SONORA LATE IN THE WEEK...RESULTING IN AN INFLUX OF MOISTURE. FORECAST IS FOR BELOW CLIMO POPS THROUGH MIDWEEK...FOLLOWED BY NEAR CLIMO POPS THURSDAY THROUGH SUNDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... NEW STORMS WILL CONTINUE TO DEVELOP TO THE SOUTH AND WEST OF THE PHOENIX AREA...WITH ACTIVITY SLOWLY BUILDING AROUND AND ENCROACHING ON THE TERMINALS LATER THIS MORNING AFTER 15Z...PERSISTING INTO THE AFTERNOON/EARLY EVENING. GENERALLY LIGHT WINDS AND SCT-BKN CLOUD DECKS AOA 6-8KFT ARE EXPECTED WITH PERIODS OF CIGS LOWERING TO 3-4KFT/VISIBILITIES REDUCED DOWN TO 4SM IN HEAVIER SHOWERS AND THUNDERSTORMS. STORMS DIMINISH AND SKIES EXPECTED TO IMPROVE AFTER 02Z MONDAY WITH SCT-BKN CLOUD DECKS SETTLING IN AOA 10KFT. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... ISOLATED SHOWER/THUNDERSTORM ACTIVITY WILL CONTINUE TO FILL IN OVER SOUTHEAST CALIFORNIA THIS MORNING THROUGH AT LEAST 17Z...WITH GUSTY OUTFLOWS TO 30KT POSSIBLE AT TIMES...ESPECIALLY NEAR KNYL. SCT-BKN CLOUD DECKS WITH CIGS DOWN TO AROUND 6-8KFT IN HEAVIER SHOWERS AND THUNDERSTORMS WITH SKIES/CIGS IMPROVING LATER THIS AFTERNOON. WINDS S-SELY AROUND 10-15KT THROUGH MUCH OF THE TAF PERIOD ACROSS THE LOWER COLORADO RIVER VALLEY/KBLH WITH LIGHTER SELY WINDS AT KIPL. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... A SWITCH TO A SOUTHERLY FLOW ALOFT WILL BRING DRYING CONDITIONS AND ENDING PRECIPITATION CHANCES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. SLIGHT CHANCES FOR STORMS WILL CONTINUE ACROSS SOUTH-CENTRAL ARIZONA WITH BETTER CHANCES ACROSS HIGHER TERRAIN LOCATIONS NORTH AND EAST OF PHOENIX. HUMIDITIES WILL REMAIN ELEVATED THROUGH THE ENTIRE PERIOD WITH AFTERNOON HUMIDITIES ONLY DROPPING INTO THE 20-30 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERY. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...KUHLMAN PREVIOUS DISCUSSION...HIRSCH AVIATION...MEYERS FIRE WEATHER...KUHLMAN
AREA FORECAST DISCUSSION
NWS PUEBLO CO
305 PM MDT SUN JUL 21 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 304 PM MDT SUN JUL 21 2013 DRIER AIR MASS HAS SPREAD OVER THE NORTHERN AND WESTERN PORTIONS OF THE AREA THIS AFTERNOON...DROPPING DEW POINTS INTO THE 20S OVER THE CENTRAL MOUNTAINS AND ACROSS TELLER COUNTY. LOW LEVEL MOISTURE STILL LURKS ON THE PLAINS...WHERE DEWPOINTS IN THE 50S HAVE LED TO CAPES IN EXCESS OF 2K J/KG EAST OF I-25. VERY LITTLE IN THE WAY OF FORCING/UPWARD MOTION THIS AFTERNOON...WITH ONLY VERY SPARSE MOUNTAIN CONVECTION MAINLY SOUTH OF HIGHWAY 50. HAVE ALSO SEEN A COUPLE CELLS DEVELOP THEN DISSIPATE QUICKLY OVER EASTERN EL PASO COUNTY...WHERE MOISTURE GRADIENT IS FAIRLY TIGHT AND RESIDUAL BOUNDARY FROM LAST NIGHT`S CONVECTION REMAINS. LATEST HRRR HINTS AT TSRA DEVELOPING EAST OF I-25 THIS EVENING....AND WHILE FORCING IS WEAK...LARGE CAPES ARE HARD TO IGNORE...AND WILL THROW IN SOME LOW POPS FOR THE PLAINS EARLY THIS EVENING. STILL EXPECT ANY STORMS TO DISSIPATE QUICKLY AFTER SUNSET. ON MONDAY...AIR MASS CONTINUES TO DRY...AND EVEN THE MOUNTAINS WILL BE HARD PRESSED TO SEE MORE THAN SOME MODERATE CUMULUS BUILD-UP IN THE AFTERNOON. KEPT SOME VERY LOW POPS IN PLACE OVER THE HIGHER PEAKS...BUT EVEN THESE MAY BE OVERDONE. RISING HEIGHTS AND MID-LEVEL TEMPS SUGGEST A HOT DAY IS IN STORE...AS READINGS ON THE PLAINS REACH 100F...WITH 80/90S ELSEWHERE. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 304 PM MDT SUN JUL 21 2013 THE ENTIRE EXTENDED FORECAST PERIOD CAN BE SUMMED UP IN TWO SENTENCES. AN UPPER RIDGE OF HIGH PRESSURE WILL REMAIN LOCKED INTO PLACE ACROSS THE REGION. MINOR DISTURBANCES IN THE FLOW ALOFT ROTATING AROUND THE RIDGE WILL KICK OFF ENHANCED CONVECTION TOWARDS THE LATTER HALF OF THE WEEK. NOW FOR THE SPECIFICS... MONDAY NIGHT THROUGH TUESDAY...EC...GFS AND EVEN THE NAM MODEL ARE NOW INDICATING THAT IT SHOULD REMAIN FAIRLY DRY THROUGH MUCH OF TUE...WITH ISOLATED TO LOW END SCATTERED POPS OVER THE HIGHER TERRAIN. A COLD FRONT DROPS DOWN TO THE PALMER DVD ON TUE...BUT THE LATEST RUNS INDICATE IT DOES NOT DROP SOUTH UNTIL LATE TUE...SETTING THE STAGE FOR WED. LOOK FOR MAX TEMPS ACROSS THE E PLAINS TO BE AROUND 100 DEG F ON TUE...AND IN THE MID TO UPPER 80S FOR THE HIGH VALLEYS. WEDNESDAY THROUGH FRIDAY...THE COLD FRONT WILL DROP SOUTH ACROSS THE CWA LATE TUE...WITH WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY EXPECTED FOR A MAJORITY OF THE FORECAST AREA BOTH WED AND THU. MAX TEMPS ARE EXPECTED TO BE ABOUT 10 DEGREES COOLER WITH SCATTERED POPS ALL AREAS BORDERING ON LIKELY. WED AFTN THROUGH THU AFTN LOOKS LIKE IT WILL BE THE MOST PROBABLY TIME FRAME FOR FLASH FLOOD POTENTIAL ACROSS AREA BURN SCARS. BY FRIDAY THE UPPER RIDGE AXIS STARTS TO SHIFT SLIGHTLY TO THE EAST AS THE RIDGE AMPLIFIES...AND THOUGH THERE IS STILL A GOOD CHANCE FOR CONVECTION FOR ALL AREAS...IT WILL BE DUE TO A REINFORCED MONSOON PLUME AS OPPOSED TO FRONTAL/LLVL FORCING. TEMPS ON FRI WILL BE AS COOL OR PERHAPS EVEN A COUPLE OF DEGREES COOLER. SATURDAY AND SUNDAY...EXTENDED MODELS ARE POINTING TO ANOTHER STRONGER DISTURBANCE MOVING ACROSS THE DAKOTAS AND MIDWEST ON SAT...PUSHING ANOTHER COOLD SURGE INTO EASTERN CO LATE SAT INTO SUN. WHEREAS SAT IS FORECAST TO HAVE DIURNAL CONVECTIVE ACTIVITY TIED MAINLY TO THE HIGHER TERRAIN...SUNDAY COULD BE ANOTHER ACTIVE DAY WITH WIDESPREAD CONVECTION AND SLIGHTLY COOLER TEMPS. MOORE && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 304 PM MDT SUN JUL 21 2013 ISOLATED TSRA HAVE BEEN DEVELOPING JUST EAST OF KCOS ALONG A WEAK BOUNDARY...AND WHILE CURRENT STORM MOTION SUGGESTS ACTIVITY WILL STAY EAST OF THE TERMINAL...GUSTY AND ERRATIC OUTFLOW WINDS MAY DEVELOP FOR A FEW HOURS AFTER 21Z. MAY ALSO SEE TSRA GET CLOSE ENOUGH TO PRODUCE SOME GUSTY WINDS AT KPUB...ESPECIALLY AFTER 22Z. AT KALS...MAY SEE SOME TSRA OVER THE SAN JUANS DRIFT INTO THE AREA AFTER 22Z...THOUGH AGAIN STORMS MAY DISSIPATE BEFORE THEY REACH THE TERMINAL. CONVECTION WILL DIMINISH AFTER SUNSET...AND VFR CONDITIONS EXPECTED ALL TAF SITES AFTER 03Z THIS EVENING. ON MONDAY...TAF SITES WILL STAY VFR WITH ONLY VERY SPARSE HIGH BASED CONVECTION EXPECTED OVER THE MOUNTAINS. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PETERSEN LONG TERM...MOORE AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
257 PM MDT SUN JUL 21 2013 .SHORT TERM...STRONG OUTFLOW FROM T-STORMS UP IN NEBRASKA LAST NIGHT...BACKED ACROSS NORTHEAST COLORADO EARLIER TODAY. THIS SHALLOW MOIST AIRMASS SIGNIFICANTLY INFLUENCED TEMPERATURES EAST OF THE MOUNTAINS TODAY. CURRENT TEMPERATURES ARE RUNNING SEVERAL DEGS BEHIND THOSE YESTERDAY AT THIS TIME...THEREBY CREATING A STRONG CAP UP AROUND 750 MBS NEAR THE FOOTHILLS...AND UP AROUND 700 MBS FARTHER OUT OVER THE PLAINS ACCORDING RUC SOUNDINGS AND CROSS SECTIONS. BENEATH THIS PSUEDO-FRONTAL INVERSION...BNDRY LAYER CAPE VALUES ARE NOW NEAR 700 J/KG UP AGAINST THE FOOTHILLS AND CLOSE TO 1500 J/KG IN THE FAR NORTHEAST. DO SEE THIS ENERGY BEING TAPPED NEAR THE FOOTHILLS EVEN WITH ISOLATED LOW TOP CONVECTION DRIFTING OFF THE FOOTHILLS WITH ALL OF THE CIN IN THIS AREA. FARTHER OUT ON THE PLAINS...COULD SEE THE WEAK SHORTWAVE DISTURBANCE NOW SWINGING OVER SERN WYOMING TAPPING INTO SOME OF THIS PENNED UP ENERGY RESULTING IN A FEW T-STORMS IN THE FAR NORTHEAST COUNTIES AFTER 5 PM MDT TODAY. MORE LIKELY WE/LL SEE THIS CONVECTION DURING THE EVENING HOURS WITH THE LAST OF THE CIN ERRODING AS THE SHORTWAVE PASSES BY. NOT LOOKING FOR ANY SEVERE WX OUT OF THEM...JUST PERHAPS SOME SMALL HAIL...BRIEF HEAVY RAIN AND GUSTY OUTFLOW WINDS TO AROUND 50 MPH. STORMS SHOULD END EARLIER TONIGHT WITH ARRIVAL OF DRIER AND MORE STABLE AIR BEHIND THIS SHORTWAVE. HOWEVER...LINGERING LOW LEVEL MOISTURE MAY AGAIN RESULT IN AREAS OF LOW CLOUDS AND/OR PATCHY FOG IN THE FAR NORTHEAST TOWARDS MORNING. ON MONDAY...AIRMASS APPEARS MUCH DRIER AND WARMER. WITH THE UPPER RIDGE STRENGTHENING TO OUR WEST..AND BARRING ANY UNFORESEEN MOIST OUTFLOW FROM DOWNSTREAM STORMS...SHOULD SEE TEMPERATURES EASILY CLIMBING INTO THE 90S ON THE PLAINS TOMORROW...WITH 70S AND 80S IN THE MTNS. IT/S NOT OUT THE QUESTION WE COULD SEE LOW 90S POPPING UP IN A FEW SPOTS ALONG THE UPPER COLORADO IN GRAND COUNTY. DO NOT ANTICIPATE ANY PRECIPITATION/T-STORMS ON MONDAY. .LONG TERM...OVERALL NO BIG CHANGES TO THE ONGOING TRENDS IN THE FORECAST. THE UPPER LEVEL RIDGE WILL BE CENTERED NEAR THE GREAT BASIN FOR MONDAY NIGHT INTO TUESDAY. AS A RESULT...A DRY AND STABLE NORTHWESTERLY FLOW ALOFT WILL BE OVER THE CWFA. PLENTY OF LOW LEVEL MOISTURE OVER THE NORTHEAST PLAINS...BUT TOO SUBSIDENT IN THE MID LEVELS TO ALLOW THE INITIATION OF DEEP CONVECTION FOR MOST OF THE FORECAST AREA. A WEAK SYSTEM PASSING ACROSS THE NRN GREAT PLAINS AND INTO THE MID WEST COULD BE ENOUGH TO INITIATE TSTMS OVER THE FAR NERN CORNER OF CO LATE TUESDAY. FOR THE REST OF THE WEEK...THE CENTER OF RIDGE SHIFTS EASTWARD WHICH OPENS UP WESTERN CO TO SUBTROPICAL MID MOISTURE FM THE SOUTH. BETTER TSTM COVERAGE SHOULD HELP TO SHAVE A FEW DEGREES OF THE AFTN TEMPERATURES AS WELL. THE ECMWF AND GFS BOTH SHOW BOTH DEVELOP DECENT QPF OVER THE AREA LATE WEDNESDAY AND THURSDAY...WITH A BIT OF DRYING ON FRIDAY. MDLS DIFFER AS TO HOW MUCH MOISTURE WILL BE AVAILABLE OVER THE WEEKEND SO SLGT CHC SHOULD SUFFICE FOR NOW. && .AVIATION...VFR CONDITIONS ANTICIPATED FOR THE NEXT 24 HOURS UNDER NORTHWEST FLOW ALOFT. NORTH-NORTHEAST SURFACE WINDS UNDER 12 KTS AT MOST DENVER AREA AIRPORTS SHOULD GRADUALLY BECOME EASTERLY AT SIMILAR SPEEDS AFTER 23Z AND LINGER THROUGH EARLY EVENING...THEN GO TO A DRAINAGE WIND OVERNIGHT. DIA AND APA COULD SEE GUSTY SOUTHERLY WINDS OF 10-20 KTS DEVELOPING IN THE EVENING WITH THE FORMATION A TIGHT PRES GRADIENT JUST EAST OF THE METRO AREA. AFTER SAY 08Z...SHOULD SEE WIND SPEEDS RELAX AND RESUME MORE TYPICAL SPEEDS UNDER 12KS. ON MONDAY SOUTHERLY WINDS UNDER 12KS ARE FORECAST TO GO WEST-NORTHWEST BY LATE MORNING AT SIMILAR SPEEDS. WITH FEW CLOUDS AROUND...SHOULD SEE DAYTIME TEMPERATURES RETURNING TO THE 90S. && .HYDROLOGY...NO CONCERNS AT THIS TIME. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BAKER LONG TERM....COOPER AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
316 PM EDT SUN JUL 21 2013 .DISCUSSION... CURRENTLY-TONIGHT...DEBRIS CLOUDINESS HAS JUST ABOUT EXITED THE AREA BUT CONVECTION HAS BEEN DELAYED A BIT. EXPECT SCATTERED SHOWERS/STORMS FORMING ALONG THE WEST COAST BOUNDARY TO MARCH ACROSS THE PENINSULA AS THE LATEST RAP WAS SHOWING STEERING LEVEL WINDS NEAR 15 KNOTS. WITH THE LIMITED SOLAR INSOLATION...THE EAST COAST SEA BREEZE WILL ONLY HAVE LIMITED INLAND MOVEMENT...MAINLY FROM THE CAPE SOUTHWARD. STILL THIS MAY CAUSE A FEW STRONGER STORMS THERE THROUGH EARLY EVENING. SOME POCKETS OF INSTABILITY MAY LINGER THROUGH EVENING SO WILL GO WITH CHANCE POPS IN ALL ZONES. MON-TUE...MID LEVEL RIDGE WITH AXIS JUST SOUTH OF THE AREA WILL BREAK DOWN AS A TROUGH BECOMES ESTABLISHED OVER THE EASTERN CONUS. THE LATEST GFS INDICATES SOME DRIER MID LEVEL AIR BEING ADVECTED IN FROM THE GULF SO POPS ARE EXPECTED TO DECREASE A LITTLE. HOWEVER THE WESTERLY STEERING LEVEL FLOW SHOULD FAVOR POPS CLOSE TO CLIMO (40 PERCENT) EXCEPT 50 PERCENT IN THE NORTH WHERE MOISTURE CONVERGENCE WILL BE HIGHER (NORTH OF LOW LEVEL RIDGE AXIS). WITH SURFACE RIDGE AXIS OVER THE SOUTHERN PENINSULA...THE WESTERLY FLOW SHOULD INCREASE A LITTLE EACH DAY AND BY TUE THE EAST COAST SEA BREEZE MAY BE INHIBITED ALL BUT THE FAR SOUTH. THIS SHOULD BOOST MAX TEMPS...THOUGH WILL NOT GO AS HIGH AS THE LATEST GFS WHICH HAS SOME 93-94 DEGREE HIGHS. THIS WOULD BE ESPECIALLY TRUE IF SOME UPPER LEVEL DEBRIS CLOUDS PERSIST LIKE THE PAST FEW DAYS. PREVIOUS DISCUSSION... WED-SAT...THE CENTER OF SURFACE HIGH PRESSURE OVER THE WESTERN ATLANTIC RETREATS SEAWARD AS ITS WESTWARD EMANATING AXIS FULLY ADJUSTS TO SOUTH FLORIDA AND PERHAPS EVEN AS FAR AS THE STRAITS. THIS WILL KEEP CENTRAL FLORIDA IN THE LOW-LEVEL WESTERLIES THRU THE PERIOD. TROUGHING HANGS UP OVER THE ATLANTIC SEABOARD BOTH SURFACE AND ALOFT TO KEEP WEATHER MORE DISTURBED JUST NORTH OF THE FORECAST AREA...WITH MINOR WAVES AND VORT MAXES MOVING AROUND THE BASE OF THE UPPER TROUGH. LOOKS LIKE SOME DRYING WORKS ITS WAY IN FROM THE GULF FOR SOUTH FLORIDA TO PROMPT POPS GREATER NORTH AND SOMEWHAT LOWER SOUTH LATER IN THE PERIOD. POPS AROUND 40 PERCENT NORTH AREA EACH DAY. FOR SOUTH AREA...40 PERCENT DROPPING BACK TO 30-35 PERCENT BY FRI. && .AVIATION... LATER DEVELOPING CONVECTION DUE TO DEBRIS CLOUDS BUT EXPECT ACTIVITY ALONG WEST COAST BOUNDARY TO MARCH STEADILY ACROSS THE PENINSULA...SO CHANCE POPS ARE IN ORDER THROUGH ABOUT 00Z. SOME STRONG STORMS ARE STILL POSSIBLE ESPECIALLY KMLB-KSUA WHERE BOUNDARY INTERACTIONS BECOME MORE NUMEROUS. SURFACE TO MID LEVEL WESTERLY FLOW WILL FAVOR STORMS MARCHING ACROSS THE PENINSULA FROM WEST TO EAST ON MON AFTERNOON AGAIN. && .MARINE... TONIGHT-MON...NEAR 15 KNOT SOUTHWEST WINDS EXPECTED CANAVERAL NORTHWARD THIS EVENING THEN DIMINISHING TO 10 KNOTS OR LESS LATE AND INTO MON MORNING. THE MAIN MARINER CONCERN WILL BE OFFSHORE MOVING STORMS THROUGH THIS EVENING AND AGAIN MON AFTERNOON. TUE-FRI...HIGH PRESSURE RIDGE AXIS WILL EXTEND SOUTH OF THE WATERS AND RESULT IN SOUTH/SOUTHWEST FLOW THROUGH THE PERIOD. SPEEDS SHOULD GENERALLY BE 10-15 KNOTS. EXPECT SCATTERED STORMS OVER THE MAINLAND TO SWEEP OFFSHORE EACH AFTERNOON. THE RIDGE AND STEERING LEVEL WINDS ARE FORECAST TO WEAKEN BY FRI WHICH MAY KEEP AFTERNOON STORMS MAINLY OVER THE PENINSULA. && .PRELIMINARY POINT TEMPS/POPS... DAB 73 89 75 90 / 30 50 30 50 MCO 74 92 74 91 / 20 40 20 40 MLB 74 89 72 90 / 30 40 20 40 VRB 72 90 73 90 / 20 40 20 40 LEE 75 91 75 91 / 20 40 30 50 SFB 76 92 75 91 / 20 40 30 40 ORL 75 92 76 91 / 20 40 30 40 FPR 73 89 72 90 / 20 40 20 40 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ FORECASTS...RL IMPACT WEATHER/RADAR...TES
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT SUN JUL 21 2013 .SYNOPSIS... ISSUED AT 252 AM CDT SUN JUL 21 2013 A QUIET NIGHT ACROSS THE AREA WHILE THUNDERSTORMS RAIN OVER THE CENTRAL PLAINS. THE SURFACE AND 850 MB FRONTAL BOUNDARIES RESIDE TO OUR SOUTH IN NORTHERN MISSOURI AND ARE ASSOCIATED WITH WEAKENING STORMS. ANOTHER BOUNDARY TO OUR NORTH ACROSS MINNESOTA AND WISCONSIN IS ASSOCIATED WITH ACTIVE STORMS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 252 AM CDT SUN JUL 21 2013 MAIN CONCERN IN THIS TIME FRAME IS THUNDERSTORM CHANCES TODAY AND THIS EVENING. MODELS OTHER THAN THE RAP AND HRRR HAVE A WEAK HANDLE ON THE PLAINS CONVECTION. AND THIS SYSTEM WITH ITS ASSOCIATED SHORT WAVE TROUGH/MCV WILL BE OUR WEATHER MAKER FOR TODAY. OVERALL CURRENT CONVECTIVE TRENDS IN THE PLAINS ARE WEAKENING EXCEPT FOR REDEVELOPING STORMS ON THE TAIL OF THE MCS WHICH IS REACHING THE MISSOURI RIVER. TIMING OF THE SHORT WAVE INTO OUR AREA IS SUCH THAT THE ATMOSPHERE SHOULD DESTABILIZE THROUGH THE MORNING...ALBEIT WITH SUNSHINE FILTERED BY MID AND HIGH CLOUDS. MODELS SEEM TO WEAKEN THE WAVE...AND THE NAM EVEN TAKES IT SOUTH OF THE CWA. BUT THE ATMOSPHERE SHOULD BE PRIMED FOR CONVECTION... AND IF THE SURFACE AND 850MB FRONTS ARE PULLED NORTH WITH THE TROUGH...WE WILL HAVE A FOCAL POINT FOR STORM INITIATION. SINCE FLOW IS WEAK AND MODEL FORECASTS ARE DIVERGENT ON THIS ISSUE... HAVE GENERALLY HELD POPS IN THE HIGH CHANCE RANGE. SLOW MOVING STORMS COULD PRODUCE LOCALLY HEAVY RAIN...AND THE ENVIRONMENT SUPPORTS AN ISOLATED RISK OF DOWNBURSTS. MAX TEMPS TODAY RELATIVE TO YESTERDAY WILL BE HINDERED SOME BY CLOUD COVER. OVERNIGHT LOWS WILL BE MORE REFLECTIVE OF THE WARM SECTOR IN MISSOURI AS WINDS SHIFT TO THE SOUTH TONIGHT. WOLF .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 252 AM CDT SUN JUL 21 2013 THE DEEP MOIST AIR MASS AHEAD OF AN EARLY TUE FROPA WILL CONTINUE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS MONDAY INTO MONDAY NIGHT. DEVELOPING NW ALOFT AND HIGH PRESSURE TO THEN PROVIDE DRY WEATHER AND SLIGHTLY COOLER TEMPERATURES FOR MOST OF THE UPCOMING WORKWEEK. RAIN CHANCES RETURN LATE WEEK INTO THE WEEKEND WITH TEMPERATURES POSSIBLY TRENDING WELL BELOW NORMAL BY SUNDAY. MONDAY...WEAK MID LEVEL SUBSIDENCE AND LACK OF SIGNIFICANT SURFACE BOUNDARIES WILL BE UNFAVORABLE FOR ANYTHING BEYOND ISOLATED CONVECTION OVER MOST OF THE AREA AND HAVE LOWERED POPS TO SLIGHT CHANCES FOR MOST OF THE DAY. THE EXCEPTION IS ACROSS THE FAR NW...WHERE DEVELOPING LIFT AHEAD OF AN APPROACHING SHORTWAVE AND SURFACE COLD FRONT MAY LEAD TO THUNDERSTORMS DURING LATE DAY PEAK HEATING AND HAVE CHANCE POPS. PREFRONTAL WARMING AND WEDGE OF WARM AIR AT 850 MB WILL SUPPORT HIGHS FROM THE MID 80S NORTH TO AROUND 90 SOUTH. DEW POINTS IN THE UPPER 60S TO LOWER 70S MAY DRIVE HEAT INDEX READINGS INTO THE UPPER 90S ACROSS THE SOUTH. MONDAY NIGHT INTO EARLY TUESDAY...THERE IS A SIGNIFICANT SPREAD AMONG THE MODELS WITH THE TIMING OF THE SURFACE COLD FRONT. THE GFS HAS TRENDED THE SLOWEST...NOT BRINGING THE FRONT THROUGH UNTIL MID MORNING...WHILE THE ECMWF HAS THE SURFACE WIND SHIFT WELL BEFORE SUNRISE. WILL STAY CLOSER TO A FASTER CONSENSUS KEEPING CHANCE POPS FOCUSED ON THE OVERNIGHT PERIOD...FOLLOWED BY SLIGHT CHANCES OVER MAINLY THE EAST TUESDAY MORNING. WILL CONTINUE TO HAVE A THREAT FOR LOCALLY HEAVY RAINFALL DUE TO THE HIGH PW VALUES IN PLACE MONDAY NIGHT. KEPT MINS FROM THE MID 60S NORTH TO THE LOWER 70S SOUTH. TUESDAY THROUGH THURSDAY...CANADIAN HIGH PRESSURE BUILDS SOUTH INTO GREAT LAKES UNDER A NW FLOW ALOFT TO PROVIDE A PERIOD OF SEASONABLY MILD AND LESS HUMID CONDITIONS. WED LOOKS TO BE THE COOLEST AS THE POSITIONING OF THE PASSING HIGH WILL PROVIDE A LOW LEVEL NORTHEAST FETCH AND THE COOLEST TEMPERATURES AT 850 MB. THIS MAY RESULT IN HIGHS LIMITED TO THE 70S ACROSS THE CENTRAL AND NORTH...WHILE BOTH TUE AND THU WILL LIKELY SEE WIDESPREAD LOWER TO MID 80S. THIS SEASONABLY DRY AIR MASS WILL SUPPORT LOWS IN THE 60S WITH SOME POCKETS OF 50S POSSIBLE THU MORNING. GULF MOISTURE RETURNS TO THE REGION THU NIGHT INTO FRIDAY. THIS AND A COLD FRONT SHOWN PUSHING THROUGH FRIDAY NIGHT OR SATURDAY WILL BRING THUNDERSTORM CHANCES BACK TO THE AREA. THE LATEST GFS AND ECMWF THEN DEVELOP A SIGNIFICANT UPPER TROUGH OVER THE EASTERN U.S. THAT ALLOWS HIGH PRESSURE TO SPILL INTO THE MID MS VALLEY. THIS COULD LIMIT HIGHS TO THE 70S OVER THE WEEKEND WITH LOWS IN THE 50S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1232 PM CDT SUN JUL 21 2013 UPPER LEVEL WAVE ROLLING EASTWARD ACRS WEST CENTRAL INTO NORTH CENTRAL IA ATTM...KICKING UP SHOWERS ON IT/S EASTWARD FLANK AND THUNDERSTORMS ON IT/S SOUTHERN FLANK ACRS SOUTH CENTRAL IA INTO SW IA. AHEAD OF IT FOR THE TERMINALS JUST VFR LEVEL DEBRIS CLOUDS AND SOUTHEAST BREEZE OF 5-10 KTS. THE SCTRD SHOWERS TO GET INTO THE VCNTY OF CID AND DBQ BY MID AFTERNOON AND LAST THROUGH EARLY EVENING. SOME EMBEDDED THUNDER EXPECTED IN THAT ACTIVITY AS WELL AS THE AFTERNOON PROGRESSES. THUS SOME POCKETS OF MVFR AND VARIABLE WIND GUSTS POSSIBLE THROUGH 7-8 PM THIS EVENING. HEAVIER RAIN MAY PRODUCE BOUTS OF IFR VSBYS AFTER 3 PM CDT. THESE CONDITIONS POSSIBLE FOR MLI AS WELL FROM LATE AFTERNOON THROUGH MID EVENING...BUT A CHANCE MLI COULD REMAIN IN BETWEEN THE ACTION ZONES TO THE NORTH AND SOUTH. THE SOUTHERN ACTION ZONE...THE ACTIVITY NOW ACRS SOUTH CENTRAL IA COULD BE A IMPACT AT BRL BY LATE AFTERNOON WITH BOUTS OF HEAVY RAIN/IFR VSBYS...LOWERED CIGS DOWN TO MVFR AND POSSIBLE VARIABLE GUSTY WINDS UP TO 45 KTS PRODUCED BY THE THUNDERSTORMS. CURRENT EXTRAPOLATION HAS THE BRL UNDER THE GUN OF THE SOUTH CENTRAL IA STORMS FROM 3 PM THROUGH 6 PM...WITH ADDITIONAL DEVELOPMENT LINGERING IN THAT AREA THROUGH MID EVENING. AFTER PRECIP CLEARS LATER THIS EVENING AND INTO THE OVERNIGHT...SOME MVFR AND POSSIBLE IFR FOG AT ALL TERMINALS TOWARD SUNRISE ESPECIALLY AT THE TERMINALS THAT DO MANAGE TO GET IN ON SOME RAIN THIS AFTERNOON/EVENING. WINDS BECOMING LIGHT AND VARIABLE OVERNIGHT OR LIGHT EAST-SOUTHEAST. ..12.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...WOLF SHORT TERM...WOLF LONG TERM...SHEETS AVIATION...12
AREA FORECAST DISCUSSION
NWS PADUCAH KY
456 PM CDT SUN JUL 21 2013 .UPDATE... ISSUED AT 456 PM CDT SUN JUL 21 2013 AFTER LOOKING AT NEW HRRR MODEL REFLECTIVITY DATA AND 18Z NAM...IT APPEARS HEAVY RAIN IS MORE LIKELY IN SW INDIANA...SE ILLINOIS...AND NW KENTUCKY LATE TONIGHT INTO EARLY MONDAY. 850 MB LOW LEVEL FLOW IS FORECAST TO STRENGTHEN TO AROUND 20 KNOTS...WITH STRONG INDICATIONS OF A BACKBUILDING MCS. RAISED POPS FOR THE OVERNIGHT HOURS TO CATEGORICAL OR LIKELY IN NE COUNTIES. THE ENSEMBLE MEANS OF THE SREF AND GFS ALSO SHOW QPF BULLSEYES IN THAT AREA OVERNIGHT. SURFACE TO 850 MB CONVERGENCE AXIS IS FORECAST TO BE IN THAT AREA WITH A 500 MB SHORTWAVE TROUGH JUST UPSTREAM. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... ISSUED AT 215 PM CDT SUN JUL 21 2013 MAIN FORECAST CONCERN TONIGHT IS HEAVY RAIN POTENTIAL. LOTS OF MOISTURE AND INSTABILITY IS IN PLACE...ALONG WITH A BROAD AREA OF WEAK LIFT. THE PRIMARY LIFTING MECHANISM IS A 500 MB SHORTWAVE ADVANCING EAST/SOUTHEAST ACROSS CENTRAL MISSOURI. CONVECTION HAS BEEN SLOWLY INCREASING THIS AFTERNOON ALONG AND SOUTH OF A WEAK WARM FRONT THAT EXTENDS FROM THE LOWER OHIO VALLEY TO NORTHWEST ARKANSAS. THE STORMS WILL CONTINUE TO INCREASE THROUGH THE EARLY EVENING HOURS...AIDED BY THE APPROACHING SHORTWAVE AND WARM FRONTAL CONVERGENCE. WILL MENTION HEAVY RAIN IN GRIDS AND ZONES. LOW LEVEL WIND SPEEDS ARE CURRENTLY A LITTLE LOWER THAN OPTIMUM FOR AN ORGANIZED FLOODING THREAT. HOWEVER...RAP MODEL RUNS INDICATE SOME INCREASE AND BACKING OF LOW LEVEL WINDS LATE TODAY AND THIS EVENING. POTENTIAL FOR EXCESSIVE RAINFALL AND LOCAL FLOODING WILL NEED TO BE MONITORED THROUGH EVENING. LATER TONIGHT AND MONDAY MORNING...WEAKENING INSTABILITY AND DECREASING UPPER SUPPORT SHOULD BRING A GRADUAL DECREASE IN COVERAGE AND INTENSITY OF THE PRECIP. TEMPS ON MONDAY WILL DEPEND ON TIMING OF PARTIAL CLEARING...WHICH SHOULD TAKE PLACE FROM WEST TO EAST AS THE DAY GOES ON. WILL CONTINUE WITH PREVIOUS FORECASTS THAT ARE CLOSER TO GFS MOS THAN THE COOLER NAM MOS. A RELATIVE LULL IN PRECIP CHANCES IS EXPECTED MONDAY NIGHT. ON TUESDAY...A COLD FRONT WILL MOVE SOUTHEAST INTO SOUTHERN ILLINOIS AND SE MISSOURI BY LATE IN THE DAY. THE FRONT SHOULD ARRIVE DURING PEAK HEATING AND INSTABILITY...SO WILL CONTINUE WITH POPS ABOVE MOS GUIDANCE. PRECIP WATER VALUES WILL BE SOMEWHAT LOWER DUE TO A MORE VEERED /WEST TO NORTHWEST/ DEEP LAYER FLOW...WHICH IS WHY POPS WILL BE KEPT BELOW THE LIKELY CATEGORY. FLOW FIELDS WILL BE SOMEWHAT STRONGER WITH THIS SYSTEM...SO THE POTENTIAL FOR ISOLATED SEVERE STORMS EXISTS. CONVECTION SHOULD DIMINISH WITH THE PASSAGE OF THE COLD FRONT ACROSS THE LOWER OHIO VALLEY LATE TUESDAY NIGHT. .LONG TERM /WEDNESDAY THROUGH SUNDAY/... ISSUED AT 215 PM CDT SUN JUL 21 2013 THE MODELS ARE IN GENERAL AGREEMENT WITH FRONT ALONG OUR SOUTHERN BORDER BY 12Z WED. HOWEVER THE GFS AND THE NAM PUSH IT ON THROUGH LIMITING ANY PRECIP CHC AFTER 12Z WED. THE 00Z SUNDAY ECMWF LINGERS PRECIP OVER THE AREA ALL DAY WED. CURRENT GRIDS REFLECT HIGHEST PROB WOULD BE OVER SEMO AND LATEST RUNS SUPPORT THAT. HOWEVER WILL TRY TO LOWER POPS NORTH AND EAST AS PREVIOUS SHIFT DID AND CONTINUE THE TREND TOWARD A DRIER WED. IF THE 12Z ECMWF FOLLOWS THAT TREND THE MID SHIFT WILL BE ABLE TO BETTER DEFINE THE CHC. SO THIS TIME FRAME REMAINS A LITTLE SUSPECT FOR NOW WITH EITHER NORTH WINDS VIA NAM GFS OR STALLED FRONT ECMWF. THE 12Z UKMET SHOWS THE FRONT ALONG THE SOUTHERN BORDER AS WELL BUT THE RUN ENDS AT 12Z BUT APPEARS TO FAVOR THE WETTER ECMWF. FOR THE LATE WEEK CHC THE THE GFS BRINGS A FRONT THROUGH BUT THE ECMWF AND DGEX BRING AN MCS OUT OF THE CENTRAL PLAINS FRIDAY WITH A COLD FRONT IN ITS WAKE SATURDAY. THE GFS IS A LITTLE VOID OF THE MCS FEATURE AND WILL LEAN TOWARD THE ECMWF AND DGEX SOLUTION...BUT USE THE SLOWER TIMING OF THE ECMWF FOR THIS FEATURE. WILL MAINTAIN A SLGT CHC SAT NGT IN THE EAST. WILL KEEP SUNDAY DRY WITH MUCH COOLER AND DRIER AIR COMING INTO THE REGION. AS FOR TEMPS IF THE EXTENDED INIT COMES TO FRUITION IT WILL BE A MUCH COOLER AND WE COULD SEE SOME RECORD OR NEAR RECORD COOL TEMPS EARLY NEXT WEEK. THE OPPOSITE OF LAST SUMMER RECORD SETTING HEAT. && .AVIATION... ISSUED AT 1230 PM CDT SUN JUL 21 2013 AREAS OF LOW CLOUDS WILL CONTINUE TO LIFT THIS AFTERNOON...WITH LINGERING POCKETS OF MVFR CIGS BECOMING VFR EARLY. WITH DIURNAL HEATING AND DESTABILIZATION...SHOWERS AND STORMS WILL SLOWLY INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON. EXPECT PEAK COVERAGE TO OCCUR EARLY THIS EVENING...ENHANCED BY AN UPPER LEVEL DISTURBANCE APPROACHING FROM THE WEST. IT IS TOO EARLY TO PINPOINT THE TIMING OF STORMS...BUT IT APPEARS LIKELY EACH TAF SITE WILL RECEIVE AT LEAST SOME RAIN THIS AFTERNOON OR EVENING. BRIEF IFR CONDITIONS ARE POSSIBLE IN ANY STORMS. CONVECTION SHOULD FADE WITH LOSS OF HEATING...AND MAINLY DRY CONDITIONS ARE EXPECTED OVERNIGHT. SOME LIGHT FOG OR PATCHY LOW CLOUDS ARE POSSIBLE LATE AT NIGHT AND MONDAY MORNING. DIURNAL CU WILL FORM AGAIN BY MIDDAY MONDAY. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ UPDATE...MY SHORT TERM...MY LONG TERM...KH AVIATION...MY
AREA FORECAST DISCUSSION
NWS JACKSON KY
546 PM EDT SUN JUL 21 2013 .UPDATE... ISSUED AT 544 PM EDT SUN JUL 21 2013 A CONTINUED LINE OF SCT TRAINING STORMS EXTENDS ACROSS THE NORTHERN HALF OF THE CWA ALONG SOME WEAK HORIZONTAL BOUNDARY. PREVIOUS FORECAST HAD SHOWERS ENDING OVER THE NW...BUT SO LONG AS THIS BOUNDARY REMAINS IN PLACE...EXPECT ISOLATED TO SCT SHOWERS AND THUNDERSTORMS TO CONTINUE OVER THIS AREA FOR THE NEXT COUPLE HOURS. ALSO ADDED IN SOME ISOLATED POPS FOR SOME AREAS OVERNIGHT...MAINLY BEFORE MIDNIGHT...BASED ON LATEST HI RES MODEL RUNS AND CURRENT FORECAST TRENDS. ADDED CURRENT OBSERVATIONS INTO ONGOING FORECAST AS WELL. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 325 PM EDT SUN JUL 21 2013 MORNING SHOWERS AND THUNDERSTORMS HAVE SHIFTED OFF TO THE SOUTH...BUT THANKS TO SOME HEATING ACROSS THE EAST...ADDITIONAL SHOWERS AND THUNDERSTORMS HAVE DEVELOPED TO THE EAST OF JACKSON...TOWARDS PRESTONSBURG AND INEZ. THIS ACTIVITY WILL SLOWLY PUSH EAST THROUGH THE REST OF THE AFTERNOON AND EVENING BEFORE EXITING EASTERN KENTUCKY. IN THE WAKE OF THIS ACTIVITY IT LOOKS LIKE A FAIRLY QUIET MID TO LATE EVENING IS ANTICIPATED AS SUBSIDENCE AHEAD OF THE APPROACHING TROUGH AXIS ACROSS THE CENTRAL PLAINS TAKES HOLD. HRRR IS IN LINE WITH CONDITIONS QUIETING DOWN THIS EVENING. WITH THE SYNOPTIC FORCING OVERSPREADING THE AREA LATE TONIGHT INTO TOMORROW MORNING...WILL BRING A PERIOD OF HIGH POPS BACK INTO THE FORECAST. GIVEN THE RAIN THIS AFTERNOON...AND POTENTIAL HEAVY RAIN WITH THE SYNOPTIC FEATURE LATE TONIGHT...GOING TO CONTINUE ON WITH THE FLASH FLOOD WATCH. IN FACT...THE NAM SPITS OUT MORE THAN AN INCH OF RAIN ACROSS A GOOD CHUNK OF THE AREA LATE TONIGHT AND TOMORROW...SO THE POTENTIAL FOR HEAVY RAIN CONTINUES. THIS IS ESPECIALLY TRUE WITH PWATS SITTING UP AROUND 1.8-2.0 INCHES. GOOD SHOWER AND THUNDERSTORM COVERAGE SHOULD CONTINUE TOMORROW AS THE MID LEVEL WAVE PUSHES EAST ACROSS THE AREA. COVERAGE SHOULD DIMINISH TOMORROW EVENING INTO THE NIGHTTIME HOURS...ALTHOUGH SHOWERS AND THUNDERSTORMS COULD CONTINUE THROUGH TOMORROW NIGHT AS WELL. CERTAINLY AN ACTIVE PERIOD SETTING UP. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 325 PM EDT SUN JUL 21 2013 THE MODELS ESSENTIALLY AGREE ON THE GENERAL EVOLUTION OF MID LEVEL TROUGHING OVER THE OHIO VALLEY AND GREAT LAKES THROUGH THE EXTENDED. HOWEVER...THERE REMAINS MUCH DISAGREEMENT WITH RESPECT TO TIMING AND TRACKS OF THE VARIOUS SHORTWAVES THAT WILL MOVE THROUGH THE AREA LATER THIS WEEK AND INTO NEXT WEEKEND. THE ECMWF TAKES A KEY ONE OF THESE INTO THE OHIO VALLEY ON WEDNESDAY HELPING TO BOTTOM OUT THIS FIRST ITERATION OF A TROUGH. ANOTHER FOLLOWS...THOUGH...RIGHT ON THE HEELS OF THE FIRST...THAT NIGHT WHICH WILL SERVE TO SHIFT THE TROUGH EAST OF KENTUCKY ALLOWING SOME BRIEF HEIGHT RISES INTO THE CWA TO CLOSE OUT THE WORK WEEK. HEIGHTS WILL START TO FALL AGAIN ON SATURDAY WHEN A RATHER STRONG WAVE WILL MOVE DUE EAST OUT OF THE CENTRAL PLAINS AND TOWARD THE OHIO VALLEY. UNLIKE YESTERDAY...THIS FEATURE HAS GAINED SOME SUPPORT FROM THE GFS...JUST NOT AS STRONG. IN CONJUNCTION WITH THIS SATURDAY WAVE...ANOTHER SWEEPS DOWN FROM SOUTH CENTRAL CANADA LATER THAT NIGHT INTO EARLY SUNDAY RESTORING A DEEP TROUGH OVER THE REGION. GIVEN THE SIMILARITIES IN THE OVERALL PATTERN...WILL FAVOR A CONSENSUS OF THE OPERATIONAL GFS AND ECMWF SOLUTIONS AS A STARTING POINT FOR THE EXTENDED GRIDS. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF THE SOUPY AND UNSETTLED CONDITIONS FROM THE SHORT TERM INTO THE DAY TUESDAY. THIS WILL MEAN A THREAT OF CONVECTION AND POSSIBLY EXCESSIVE RAIN FALL. A FRONTAL BOUNDARY WILL START TO MOVE SOUTH THROUGH THE AREA LATER THAT NIGHT AND ON WEDNESDAY AS LOW PRESSURE CONSOLIDATES OVER THE MID ATLANTIC COASTAL STATES. HIGH PRESSURE AND SOMEWHAT DRIER AIR WILL MOVE INTO KENTUCKY ON THURSDAY AND PROVIDE A WELCOMED CHANGE OF AIR MASS AND BREAK FROM THE SHOWER AND THUNDERSTORM THREATS. THIS HIGH WILL MOVE EAST ON FRIDAY AND FRIDAY NIGHT AS A NEW AREA OF LOW PRESSURE TAKES SHAPE OVER THE CENTRAL PLAINS LOOKING TO SLIP INTO KENTUCKY ON SATURDAY. THIS WILL BRING RENEWED CHANCES OF SHOWERS AND THUNDERSTORMS TO EAST KENTUCKY FOR THE WEEKEND...ALONG WITH SOMEWHAT COOLER TEMPS. THE SFC LOW ASSOCIATED WITH THIS LOOKS TO PASS THROUGH ON SUNDAY WITH THE BEST PCPN EXITING LATER IN THE DAY...WHILE THE COOLER AIR REMAINS TO START THE NEW WORK WEEK. THE CR GRID LOAD CAME IN REASONABLE CONSIDERING THE DIFFERENCES IN THE SPECIFICS FROM THE MODELS. DID NUDGE DOWN POPS A BIT FROM THURSDAY INTO FRIDAY NIGHT...MORE TOWARD THE 00Z OPERATIONAL ECMWF. ALSO...ADJUSTED OVERNIGHT LOWS A TAD FOR WEDNESDAY AND THURSDAY NIGHTS TO HIGHLIGHT RIDGE AND VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 135 PM EDT SUN JUL 21 2013 A FRONTAL BOUNDARY DRAPED ACROSS THE AREA WILL CONTINUE TO PRODUCE OCCASIONAL SHOWERS AND THUNDERSTORMS THROUGH THE REST OF TODAY. WHILE A BREAK MAY OCCUR THIS EVENING...A SHORT WAVE TROUGH WILL PUSH ACROSS THE AREA LATE TONIGHT INTO MONDAY BRINGING MORE WIDESPREAD RAIN TO THE AREA. AS FOR THE REST OF THE DAY...BASED ON CURRENT RADAR TRENDS...WOULD NOT ANTICIPATE MANY RESTRICTIONS AT THE TAF SITES AS KLOZ AND SME ARE STUCK IN LIGHT RAIN AT THE MOMENT. BETTER VISIBILITY/CEILING RESTRICTIONS WILL ARRIVE WITH THE SHORTWAVE LATE TONIGHT AND DROPPED VISIBILITIES TO BETWEEN 1 AND 3 MILES WITH SOME LOWER CIGS. WE WILL PROBABLY SEE A PERIOD OF LOWER VISIBILITIES AND CEILINGS BUT WILL LET FUTURE TAF FORECAST HANDLE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...JMW SHORT TERM...KAS LONG TERM...GREIF AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
325 PM EDT SUN JUL 21 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 325 PM EDT SUN JUL 21 2013 MORNING SHOWERS AND THUNDERSTORMS HAVE SHIFTED OFF TO THE SOUTH...BUT THANKS TO SOME HEATING ACROSS THE EAST...ADDITIONAL SHOWERS AND THUNDERSTORMS HAVE DEVELOPED TO THE EAST OF JACKSON...TOWARDS PRESTONSBURG AND INEZ. THIS ACTIVITY WILL SLOWLY PUSH EAST THROUGH THE REST OF THE AFTERNOON AND EVENING BEFORE EXITING EASTERN KENTUCKY. IN THE WAKE OF THIS ACTIVITY IT LOOKS LIKE A FAIRLY QUIET MID TO LATE EVENING IS ANTICIPATED AS SUBSIDENCE AHEAD OF THE APPROACHING TROUGH AXIS ACROSS THE CENTRAL PLAINS TAKES HOLD. HRRR IS IN LINE WITH CONDITIONS QUIETING DOWN THIS EVENING. WITH THE SYNOPTIC FORCING OVERSPREADING THE AREA LATE TONIGHT INTO TOMORROW MORNING...WILL BRING A PERIOD OF HIGH POPS BACK INTO THE FORECAST. GIVEN THE RAIN THIS AFTERNOON...AND POTENTIAL HEAVY RAIN WITH THE SYNOPTIC FEATURE LATE TONIGHT...GOING TO CONTINUE ON WITH THE FLASH FLOOD WATCH. IN FACT...THE NAM SPITS OUT MORE THAN AN INCH OF RAIN ACROSS A GOOD CHUNK OF THE AREA LATE TONIGHT AND TOMORROW...SO THE POTENTIAL FOR HEAVY RAIN CONTINUES. THIS IS ESPECIALLY TRUE WITH PWATS SITTING UP AROUND 1.8-2.0 INCHES. GOOD SHOWER AND THUNDERSTORM COVERAGE SHOULD CONTINUE TOMORROW AS THE MID LEVEL WAVE PUSHES EAST ACROSS THE AREA. COVERAGE SHOULD DIMINISH TOMORROW EVENING INTO THE NIGHTTIME HOURS...ALTHOUGH SHOWERS AND THUNDERSTORMS COULD CONTINUE THROUGH TOMORROW NIGHT AS WELL. CERTAINLY AN ACTIVE PERIOD SETTING UP. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 325 PM EDT SUN JUL 21 2013 THE MODELS ESSENTIALLY AGREE ON THE GENERAL EVOLUTION OF MID LEVEL TROUGHING OVER THE OHIO VALLEY AND GREAT LAKES THROUGH THE EXTENDED. HOWEVER...THERE REMAINS MUCH DISAGREEMENT WITH RESPECT TO TIMING AND TRACKS OF THE VARIOUS SHORTWAVES THAT WILL MOVE THROUGH THE AREA LATER THIS WEEK AND INTO NEXT WEEKEND. THE ECMWF TAKES A KEY ONE OF THESE INTO THE OHIO VALLEY ON WEDNESDAY HELPING TO BOTTOM OUT THIS FIRST ITERATION OF A TROUGH. ANOTHER FOLLOWS...THOUGH...RIGHT ON THE HEELS OF THE FIRST...THAT NIGHT WHICH WILL SERVE TO SHIFT THE TROUGH EAST OF KENTUCKY ALLOWING SOME BRIEF HEIGHT RISES INTO THE CWA TO CLOSE OUT THE WORK WEEK. HEIGHTS WILL START TO FALL AGAIN ON SATURDAY WHEN A RATHER STRONG WAVE WILL MOVE DUE EAST OUT OF THE CENTRAL PLAINS AND TOWARD THE OHIO VALLEY. UNLIKE YESTERDAY...THIS FEATURE HAS GAINED SOME SUPPORT FROM THE GFS...JUST NOT AS STRONG. IN CONJUNCTION WITH THIS SATURDAY WAVE...ANOTHER SWEEPS DOWN FROM SOUTH CENTRAL CANADA LATER THAT NIGHT INTO EARLY SUNDAY RESTORING A DEEP TROUGH OVER THE REGION. GIVEN THE SIMILARITIES IN THE OVERALL PATTERN...WILL FAVOR A CONSENSUS OF THE OPERATIONAL GFS AND ECMWF SOLUTIONS AS A STARTING POINT FOR THE EXTENDED GRIDS. SENSIBLE WEATHER WILL FEATURE A CONTINUATION OF THE SOUPY AND UNSETTLED CONDITIONS FROM THE SHORT TERM INTO THE DAY TUESDAY. THIS WILL MEAN A THREAT OF CONVECTION AND POSSIBLY EXCESSIVE RAIN FALL. A FRONTAL BOUNDARY WILL START TO MOVE SOUTH THROUGH THE AREA LATER THAT NIGHT AND ON WEDNESDAY AS LOW PRESSURE CONSOLIDATES OVER THE MID ATLANTIC COASTAL STATES. HIGH PRESSURE AND SOMEWHAT DRIER AIR WILL MOVE INTO KENTUCKY ON THURSDAY AND PROVIDE A WELCOMED CHANGE OF AIR MASS AND BREAK FROM THE SHOWER AND THUNDERSTORM THREATS. THIS HIGH WILL MOVE EAST ON FRIDAY AND FRIDAY NIGHT AS A NEW AREA OF LOW PRESSURE TAKES SHAPE OVER THE CENTRAL PLAINS LOOKING TO SLIP INTO KENTUCKY ON SATURDAY. THIS WILL BRING RENEWED CHANCES OF SHOWERS AND THUNDERSTORMS TO EAST KENTUCKY FOR THE WEEKEND...ALONG WITH SOMEWHAT COOLER TEMPS. THE SFC LOW ASSOCIATED WITH THIS LOOKS TO PASS THROUGH ON SUNDAY WITH THE BEST PCPN EXITING LATER IN THE DAY...WHILE THE COOLER AIR REMAINS TO START THE NEW WORK WEEK. THE CR GRID LOAD CAME IN REASONABLE CONSIDERING THE DIFFERENCES IN THE SPECIFICS FROM THE MODELS. DID NUDGE DOWN POPS A BIT FROM THURSDAY INTO FRIDAY NIGHT...MORE TOWARD THE 00Z OPERATIONAL ECMWF. ALSO...ADJUSTED OVERNIGHT LOWS A TAD FOR WEDNESDAY AND THURSDAY NIGHTS TO HIGHLIGHT RIDGE AND VALLEY TEMPERATURE DIFFERENCES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 135 PM EDT SUN JUL 21 2013 A FRONTAL BOUNDARY DRAPED ACROSS THE AREA WILL CONTINUE TO PRODUCE OCCASIONAL SHOWERS AND THUNDERSTORMS THROUGH THE REST OF TODAY. WHILE A BREAK MAY OCCUR THIS EVENING...A SHORT WAVE TROUGH WILL PUSH ACROSS THE AREA LATE TONIGHT INTO MONDAY BRINGING MORE WIDESPREAD RAIN TO THE AREA. AS FOR THE REST OF THE DAY...BASED ON CURRENT RADAR TRENDS...WOULD NOT ANTICIPATE MANY RESTRICTIONS AT THE TAF SITES AS KLOZ AND SME ARE STUCK IN LIGHT RAIN AT THE MOMENT. BETTER VISIBILITY/CEILING RESTRICTIONS WILL ARRIVE WITH THE SHORTWAVE LATE TONIGHT AND DROPPED VISIBILITIES TO BETWEEN 1 AND 3 MILES WITH SOME LOWER CIGS. WE WILL PROBABLY SEE A PERIOD OF LOWER VISIBILITIES AND CEILINGS BUT WILL LET FUTURE TAF FORECAST HANDLE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ SHORT TERM...KAS LONG TERM...GREIF AVIATION...KAS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
401 PM EDT SUN JUL 21 2013 .SYNOPSIS... HIGH PRESSURE REMAINS ANCHORED OFF THE SOUTHEAST COAST DURING THE EARLY PORTION OF THIS WEEK...AS A COLD FRONT BECOMES NEARLY STATIONARY FROM THE OHIO VALLEY TO THE NORTHERN MID ATLANTIC STATES. MEANWHILE...AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL PERSIST ACROSS THE REGION. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... CURRENT SATELLITE IMAGERY AND REGIONAL RADAR MOSAIC INDICATE AN ORGANIZED LINE OF THUNDERSTORMS EXTENDING FROM NORTHERN VA SW ALONG THE PIEDMONT AND MOVING EAST. THIS LINE OF STORMS IS BEGIN DRIVEN BY THE TAIL END OF A SHORTWAVE TROUGH MOVING ACROSS THE NORTHERN MID ATLANTIC...INTERACTING WITH A SURFACE TROUGH OVER THE AREA...AND FEEDING OFF AN AXIS OF >2500 J/KG OF MLCAPE PER SPC HRRR BASED MESOANALYSIS. ADDITIONAL SEA/BAY BREEZE CONVECTION IS DEVELOPING ACROSS THE LOWER BAY AND MD ATLANTIC COAST. THE PRIMARY LINE SHOULD PROGRESS EAST ACROSS CENTRAL/S-CENTRAL VA THROUGH THE LATE AFTERNOON AND EARLY EVENING. INITIALLY...0-6KM BULK SHEAR VALUES ARE PROGGED TO BE ~25KT BEFORE DECAYING BY EARLY EVENING. THEREFORE...THE BEST CHANCE OF AN ISOLATED SEVERE STORM (MAINLY WIND GUST) WOULD BE ACROSS THE NORTHERN PORTION OF THE AREA THROUGH THE REMAINDER OF THE AFTERNOON. THE SOUTHERN END OF THE LINE SHOULD EVENTUALLY DISSIPATE THIS EVENING DUE TO THE LOSS OF SURFACE HEATING AND A LACK OF LARGE SCALE FORCING AS THE SHORTWAVE ENERGY PULLS TOWARD NEW ENGLAND. FARTHER NE IN THE LOCAL AREA...SCT POPS WILL BE MAINTAINED THROUGH THE EVENING/EARLY OVERNIGHT IN CLOSER PROXIMITY TO THE SHORTWAVE. WARM AND HUMID CONDITIONS WILL PERSIST OVERNIGHT WITH LOWS IN THE LOW/MID 70S. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... THE OVERALL PATTERN REMAINS UNSETTLED MONDAY AS A SURFACE BOUNDARY/WEAK LOW STALL OVER THE AREA. ADDITIONALLY...A VIGOROUS TROUGH CARVES OVER THE GREAT LAKES. A LEADING SHORTWAVE EJECTS OUT OF THE TROUGH ACROSS THE OHIO VALLEY TOWARD THE APPALACHIANS MONDAY AFTERNOON/EVENING. HENCE...HIGH CHANCE/LOW-END LIKELY POPS ARE FORECAST MONDAY AFTN/EVENING. AFTERNOON HIGHS WILL TREND DOWN SLIGHTLY DUE TO INCREASED CLOUD COVER AND A HIGHER PROBABILITY OF SHOWERS/TSTMS (AND SHIFTING WIND DIRECTION MAINLY N)...ALTHOUGH DEWPOINTS WILL REMAIN IN THE LOW/MID 70S. HIGHS SHOULD RANGE FROM THE MID/UPPER 80S TO AROUND 90 MONDAY. ANY SEVERE THREAT LOOKS RATHER LIMITED MONDAY...WITH THE MAIN CONCERN AGAIN BEING HEAVY RAIN FROM SLOW MOVING STORMS. THE PARENT TROUGH PIVOTS N OF THE GREAT LAKES TUESDAY AS A SECONDARY WAVE LIFTS ACROSS THE MID ATLANTIC. THE LATEST DATA BRINGS THE WAVE THROUGH EARLIER IN THE DAY...FOLLOWED BY WESTERLY MID-LEVEL FLOW BY LATER AFTERNOON. GIVEN THIS...POPS HAVE BEEN LOWERED...ESPECIALLY W. HOWEVER..A WELL-DEFINED LEE SIDE TROUGH REMAINS OVER THE AREA...SO WILL MAINTAIN 30 POPS W...TO 40 E. HIGHS SHOULD AVERAGE IN THE UPPER 80S TO LOW 90S. THE 21/12Z GFS/NAM BRING YET ANOTHER SHORTWAVE TROUGH THROUGH THE REGION WEDNESDAY. THE MAIN MOISTURE FEED MAY BE WELL OFF THE COAST BY THIS TIME...SO WILL GO NO HIGHER THAN CHANCE POPS AT THIS TIME. HIGHS SHOULD AGAIN RANGE FROM THE UPPER 80S TO LOW 90S. LOWS THROUGH THE PERIOD SHOULD RANGE FROM 70-75. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... UPR TROF OVR THE ERN THIRD OF THE U.S. WED NGT THRU THU...WILL SHIFT EWRD AND OFFSHR THU NGT THRU FRI. THIS WILL PUSH FRNTL BNDRY ALNG OR JUST OFFSHR AT THE BEGINNING OF THE PERIOD...FARTHER OUT TO SEA. WEAK HI PRES WILL BLD INTO AND OVR THE AREA FOR FRI NGT INTO SAT. THEN...ANOTHER SHRTWV TROF AND ASSOCIATED COLD FRONT WILL APPROACH AND MOVE INTO THE REGION LATE SAT NGT THRU SUN. AT THIS TIME...WILL NOT BE GOING ANY HIGHER THAN 20% OR 30% THRU THE PERIOD...DUE TO LOW CONFIDENCE OF COVERAGE. MIN TEMPS WILL BE IN THE UPR 60S TO MID 70S THU MORNG...AND MAINLY IN THE MID 60S TO LWR 70S FRI...SAT AND SUN MORNGS. MAX TEMPS WILL GENERALLY BE IN THE MID TO UPR 80S THRU THE PERIOD. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... AFTER SEVERAL HOURS OF OCNL MVFR CIGS AT EACH OF THE TAF SITES...VFR IS EXPECTED TO PREVAIL DURING THE AFTN. THE FOCUS WILL TURN TO SCATTERED CONVECTION ACROSS MUCH OF THE AREA. THIS IS MOST LIKELY TO OCCUR AT RIC AND SBY WHERE TEMPO GROUPS FOR TSTMS ARE IN PLACE TOWARD EARLY EVENING. CONFIDENCE IN THE TIMING FOR THE OTHER THREE SITES IS NOT HIGH ENOUGH TO INCLUDE TSTMS AT THIS TIME. SOME MVFR IS EXPECTED TO DEVELOP AGAIN MONDAY MORNING SIMILAR TO THE LAST SEVERAL MORNINGS. LOW PRESSURE ASSOCIATED WITH AN APPROACHING COLD FRONT HAS WEAKENED RESULTING IN DIMINISHING WINDS OVER THE AREA. WINDS WILL BE LIGHT AND VARIABLE DURING MUCH OF THE TAF PERIOD. OUTLOOK...SCATTERED MAINLY AFTN AND EARLY EVENING TSTMS CAN BE EXPECTED MON THROUGH FRI WITH THE HIGHEST CHANCES MON AND WED. AVIATION CONDS MAY LWR BRIEFLY IN HEAVIER PCPN. PATCHY IFR FOG NEAR SUNRISE CANNOT BE RULED BUT NO WIDESPREAD IFR IS INDICATED THROUGH MID WEEK. && .MARINE... SUB-SCA CONDS WILL PREVAIL OVER THE NEXT SEVERAL DAYS OVER AREA WATERS. SWELLS WILL IMPACT THE COASTAL WATERS DUE TO STRONGER WINDS ASSOCIATED WITH THE BERMUDA HIGH WELL OFF THE COAST. ADDED SOME HEIGHT TO THE SEAS DUE TO THE SWELL...ESPECIALLY MONDAY NIGHT AND EARLY TUESDAY...BUT KEPT THEM BELOW 5 FT FOR OUR COASTAL ZONES. EXPECT LOCALLY STRONGER WNDS IN SHOWERS AND TSTMS THRU THE PERIOD. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...AJZ/LKB NEAR TERM...AJZ SHORT TERM...AJZ/LKB LONG TERM...TMG AVIATION...LSA MARINE...LSA
SHORT TERM FORECAST DISCUSSION FOR DETAILS ON CONVECTIVE INITIATION
AND SUPPORTING SEVERE WX PARAMETERS/INDICES ON MONDAY AFTERNOON. A
LOT OF WHAT HAPPENS MONDAY EVENING WILL BE DEPENDENT ON CONVECTIVE EVOLUTION MONDAY AFTERNOON. THE BEST INSTABILITY APPEARS TO BE ALONG A THETA-E AXIS JUST AHEAD OF THE SFC COLD FRONT OVER THE WESTERN SHORE OF UPPER MI AT THE START OF THE PERIOD...SO DO NOT EXPECT CONVECTION TO CLEAR OUT UNTIL THE FRONTAL PASSAGE. THE MAIN QUESTION IS IF THE ENVIRONMENT ON MONDAY AFTERNOON REMAINS CAPPED ENOUGH TO MAKE THE FIRST SUBTLE MID-LEVEL WAVE INERT AS IT PASSES OVERHEAD EARLY MONDAY AFTERNOON. IF THIS IS THE CASE...EARLY MONDAY EVENING COULD BE QUITE ACTIVE ALONG THE FRONT...ESPECIALLY NEAR THE WI BORDER ONCE FRONTAL FORCING INITIATES MORE WIDESPREAD CONVECTION. THE LACK OF MINIMAL AFTERNOON CONVECTION COULD ALLOW MLCAPE VALUES TO REACH 1000 TO 1500 J/KG ACROSS THE WEST. WHILE THE BEST SHEAR WILL HAVE DIMINISHED SOMEWHAT BY THIS POINT AS THE SFC FLOW VEERS TO THE SW...40KTS OF 0-6KM SHEAR WILL BE MORE THAN ENOUGH TO SUPPORT SUPERCELLS ALONG THE COLD FRONT. ALSO...WITH THE SHORTWAVE TROUGH MOVING ESE...MID-LEVEL WESTERLY WINDS WILL CREATE ABOUT 60 DEGREES OF SEPARATION BETWEEN THE SFC FRONT AND SHEAR VECTORS. SO...WOULD NOT BE SURPRISED TO SEE A WINDOW OF DISCRETE SUPERCELLS ALONG THE WI BORDER IN THE EARLY EVENING. AS FOR THE MAIN SEVERE THREAT...THINGS GET A LITTLE TRICKY GIVEN VEERING SFC FLOW AND FREEZING LEVELS AOA 14KFT. WITH DOWNDRAFT CAPE APPROACHING 1000 J/KG ALONG THE BORDER AMIDST DECENT MID-LEVEL DRY AIR...THINKING IS THAT STRONG WINDS WILL BE THE MAIN THREAT. SMALL MICROBURSTS FROM RFD/S ON ANY SUPERCELLS THAT FORM...AND SMALL BOWING SEGMENTS WILL BE OF MOST CONCERN. OVERALL...STILL THINK SEVERE CONVECTION THREAT IS MARGINAL AND QUITE CONDITIONAL...BUT PARAMETERS ARE LINING UP WELL ENOUGH TO AT LEAST DISCUSS THE POTENTIAL. THE 12Z NAM FORECAST HAS COMPLETE FRONTAL PASSAGE THROUGH THE CWA AND COASTAL WATERS OF LAKE MI BY 09Z TUESDAY. THOUGH...A BIT OF ELEVATED INSTABILITY COMBINED WITH A SECONDARY MID-LEVEL TROUGH CROSSING THE CWA BEHIND THE FRONT SUGGEST KEEPING AT LEAST SLIGHT CHANCE POPS ACROSS THE WEST AND CENTRAL UNTIL SUNRISE TUESDAY. ANY OF THIS PRECIP WILL BE ENTIRELY SHORTWAVE-DRIVEN. TUESDAY THROUGH WEDNESDAY...WEAK MID-LEVEL RIDGING ON NORTHWEST FLOW WILL BRING QUIET AND DRY CONDITIONS BY MID-WEEK. TUESDAY AND TUESDAY NIGHT LOOK TO BE A CARBON COPY OF YESTERDAY AND LAST NIGHT. HAVE LOWERED TEMPS IN BOTH PERIODS GIVEN LIGHT WINDS AND DRY AIR. PWAT VALUES UNDER 0.5 INCHES TUESDAY NIGHT WILL ALLOW FOR GOOD RADIATIONAL COOLING. THE MODELS THAT HANDLED LAST NIGHTS COOL TEMPS THE BEST ARE SHOWING LOW 40S ACROSS THE INTERIOR WEST. THEREFORE...DROPPED TEMPS SEVERAL DEGREES. BRISK NNW FLOW BEHIND THE COLD FRONT WILL ALSO BRING AN ELEVATED SWIM RISK EAST OF MARQUETTE THROUGHOUT THE DAY. BY WEDNESDAY...A WEAK SHORTWAVE TROUGH WILL BEGIN TRACKING SOUTHEAST ACROSS NORTH MANITOBA ON THE BACKSIDE OF THE DEEP EASTERN CANADIAN TROUGH. THE GEM AND GFS ARE DEPICTING A CONVECTIVELY-INDUCED SHORTWAVE DIGGING SOUTHEAST INTO WI WEDNESDAY AFTERNOON...BUT FALLING APART AS IT RUNS INTO THE RIDGE. THIS FOLLOWS THE TRACK OF WEAKLY COUPLED UPPER JETS OVER THE UPPER TO MID MS VALLEY. KEPT ANY MENTION OF PRECIP OUT OF THE DAY ON WEDNESDAY...BUT THE TREND OF THIS FORECAST WILL NEED TO BE MONITORED OVER THE NEXT COUPLE DAYS. THURSDAY AND FRIDAY...A FEW DIURNAL SHOWERS AND STORMS ARE POSSIBLE THURSDAY AFTERNOON ACROSS THE INTERIOR WEST WITH RETURN SFC MOISTURE ON THE BACKSIDE OF THE SFC HIGH. THE REST OF THE LAYER WILL REMAIN SOMEWHAT DRY...SO WILL KEEP THE CHANCE POPS FOR NOW. USED CONSENSUS POPS FOR FRIDAY AS THE MODELS BECOME DIFFERENT ON HOW THEY HANDLE THE INCOMING TROUGH FROM MANITOBA. THE GFS HAS THE TROUGH BECOMING QUITE AMPLIFIED AND BRINGS A SFC COLD FRONT THROUGH THE CWA THURSDAY NIGHT. MEANWHILE...THE ECMWF IS FAR LESS-AMPLIFIED WITH THE TROUGH AND DOES NOT PASS THE FRONT UNTIL FRIDAY MORNING. THE GEM IS EVEN SLOWER...BRINGING THE FRONT THROUGH FRIDAY AFTERNOON. SATURDAY AND SUNDAY...SHARP MID-LEVEL RIDGING DEVELOPING ACROSS THE NORTHERN PLAINS WILL BEGIN TO WORK INTO THE UPPER GREAT LAKES BEHIND THE DEPARTING TROUGH. BEING LESS AMPLIFIED...THE ECMWF TAKES LONGER TO PASS THE TROUGH ACROSS THE REGION...AND ACTUALLY STALLS IT OVER LAKE HURON AT THE VERY END OF THE PERIOD. GIVEN THE UNCERTAINTIES...WILL MAINTAIN CONSENSUS POPS FOR NEXT WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 154 PM EDT SUN JUL 21 2013 VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE FCST PERIOD. EXPECT INCREASING MID CLOUDS LATE IN THE DAY AND TONIGHT AHEAD OF AN APPROACHING DISTURBANCE. SOME SHRA ARE POSSIBLE AT KIWD AND KCMX LATE TONIGHT. SOME LOWER CIGS NEAR MVFR MAY BE POSSIBLE LATE TONIGHT AND MON MORNING AS LOW LEVEL MOISTURE ADVECTION INCREASES. HOWEVER...CONFIDENCE WAS TOO LOW MENTION IN THE TAF AT THIS TIME. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 410 PM EDT SUN JUL 21 2013 SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS LATE TONIGHT AND MONDAY AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20-25 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND THE TROUGH/COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS TUE NIGHT THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KLUBER AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
155 PM EDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 450 AM EDT SUN JUL 21 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A ZONAL FLOW OVER THE UPPER GREAT LAKES. AT THE SFC...HIGH PRESSURE DOMINATES THE UPPER GREAT LAKES. THE CLEAR SKIES AND LIGHT WINDS HAVE ALLOWED TEMPS EARLY THIS MORNING TO FALL INTO THE 40S WITH EVEN A FEW LOCATIONS REACHING THE MID TO UPPER 30S. TODAY...AS THE SFC HIGH SHIFTS EAST OF THE AREA...SRLY FLOW AND WAA WILL INCREASE AHEAD OF APPROACHING SHORTWAVE AND FRONTAL SYSTEM OVER THE NRN PLAINS. TEMPS SHOULD CLIMB INTO THE LOWER TO MID 70S INLAND WITH LOWER READINGS IN THE MID TO UPPER 60S ALONG THE GREAT LAKES. MODELS INDICATE SOME INCREASE IN 305K ISENTROPIC ASCENT OVER FAR WRN UPR MI LATE IN THE DAY ALTHOUGH BEST MOISTURE LIFT SHOULD STAY SOUTH AND WEST. WILL MAINTAIN GOING FCST OF SLIGHT CHANCE POPS OVER THE FAR WEST. TONIGHT...INCREASING 925-700 MB THETA-E ADVECTION AND 305K ISENTROPIC ASCENT SHOULD LEAD TO INCREASED CHCS FOR SHRA AND TSRA ESPECIALLY AFT MIDNIGHT AS SHORTWAVE APPROACHED FM THE WEST. LIMITING FACTOR FOR TSRA WILL BE LACK OF ELEVATED INSTABILITY AS MUCAPES ONLY A FEW HUNDRED J/KG. WILL KEEP HIGHER CHC POPS OVER FAR WEST AND TAPER TO LOW CHC 20-30 PCT POPS OVER CENTRAL COUNTIES. EXPECT LOWS GENERALLY IN THE 50S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 450 AM EDT SUN JUL 21 2013 MOST TIME SPENT ON LONG TERM WAS WITH PRECIP CHANCES MON/MON NIGHT AND ASSESSING SEVERE STORM THREAT FOR MON AFTERNOON/EVENING. LOOKING FIRST AT THE LARGE SCALE...AN UPPER TROUGH OVER THE ERN HALF OF THE CONUS WILL BE STEMMING FROM A CLOSED LOW OVER NRN QUEBEC AND AN UPPER RIDGE WILL BE OVER THE WRN CONUS AT 12Z MON. A PIECE OF UPPER ENERGY WILL MOVE ACROSS THE REGION MON INTO EARLY MON NIGHT...FOLLOWED BY OTHER SMALLER SCALE ENERGY THU NIGHT THROUGH SAT...BUT THE OVERALL PATTERN REMAINS SIMILAR THROUGH THE EXTENDED. THIS MEANS...FOR THE MOST PART...THAT COOLER WEATHER IS HERE TO STAY FOR MUCH OF THE NEXT WEEK AT LEAST. FOR THE SPECIFICS... MON/MON NIGHT...THERE WILL BE PRECIP MOVING INTO THE WRN CWA EARLY MON AS THE UPPER TROUGH AND SFC TROUGH/COLD FRONT MOVE IN. THINK THE BEST PRECIP CHANCES WILL BE DURING THE AFTERNOON/EARLY EVENING AS THE COLD FRONT MOVES THROUGH A POTENTIALLY UNSTABLE AIRMASS. QUESTIONS IS HOW MUCH CLEARING WILL RESULT AFTER MORNING RAIN...WHICH WILL EFFECT HOW MUCH INSTABILITY EXISTS IN THE AFTERNOON. IF WE CAN GET GOOD CLEARING...SBCAPE VALUES MAY BE 800-1200J/KG /HIGHEST OVER SCENTRAL UPPER MI/...AND STRONGLY VEERING WINDS THROUGH THE ATMOSPHERE WILL LEAD TO AROUND 40KTS OF 0-6KM BULK SHEAR. IF OPTIMAL CONDITIONS FOR CONVECTION DO MATERIALIZE...THEN SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS WOULD BE POSSIBLE...WITH THE BEST CHANCES OVER SCENTRAL UPPER MI. HOWEVER...AT THIS TIME...THINK THE COVERAGE OF ANY SEVERE WEATHER WILL BE MORE LIMITED DUE TO DRY AIR. FOR NOW WILL CONTINUE MENTION OF SEVERE CHANCES IN HWO/EHWO BUT STILL TOO UNCERTAIN TO PUT IN GRIDS. MON LOOKS LIKE THE WARMEST DAY IN THE NEXT WEEK AHEAD OF THE COLD FRONT...WITH HIGHS IN THE 70S TO MID 80S. POSTFRONTAL TUESDAY SHOULD BE COOLER AND SIMILAR TO YESTERDAY...WITH HIGHS AROUND 60 NEAR LAKE SUPERIOR TO THE LOW 70S SOUTH CENTRAL. SKIES SHOULD BE CLEARING BY THE AFTERNOON. WED WILL BE SLIGHTLY WARMER THAN TUESDAY AS TEMPS RECOVER SOME FROM THE COLD FRONT. SHOULD SEE SOME INCREASE IN CLOUDS FROM W TO E DURING THE AFTERNOON/EVENING AS A MORE MILD PIECE OF UPPER ENERGY SLIDES ACROSS THE CWA...BUT NO PRECIP IS EXPECTED. THERE IS MORE UNCERTAINTY LATER IN THE WEEK WHEN LOOKING AT MORE SIGNIFICANT UPPER ENERGY SLIDING INTO THE REGION...BUT PRECIP WILL CERTAINLY BE POSSIBLE LATER INTO THE WEEK. TEMPERATURES WILL CLIMB ANOTHER COUPLE OF DEGREES ON THURSDAY...BUT SHOULD AGAIN FALL INTO THE WEEKEND AS THE UPPER TROUGH MOVES OVERHEAD. USED A GENERAL CONSENSUS OF MODEL GUIDANCE FOR THIS PART OF THE FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 154 PM EDT SUN JUL 21 2013 VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE FCST PERIOD. EXPECT INCREASING MID CLOUDS LATE IN THE DAY AND TONIGHT AHEAD OF AN APPROACHING DISTURBANCE. SOME SHRA ARE POSSIBLE AT KIWD AND KCMX LATE TONIGHT. SOME LOWER CIGS NEAR MVFR MAY BE POSSIBLE LATE TONIGHT AND MON MORNING AS LOW LEVEL MOISTURE ADVECTION INCREASES. HOWEVER...CONFIDENCE WAS TOO LOW MENTION IN THE TAF AT THIS TIME. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 450 AM EDT SUN JUL 21 2013 HIGH PRESSURE WILL KEEP WINDS GENERALLY LIGHT TODAY OVER THE NORTHERN GREAT LAKES. SRLY WINDS WILL INCREASE TO AROUND 20 KNOTS LATE TONIGHT AND MONDAY AHEAD OF A LOW PRESSURE TROUGH MOVING THROUGH THE AREA. NORTH TO NORTHWEST WINDS WILL THEN INCREASE TO 20 KNOTS BY LATE MONDAY NIGHT INTO TUESDAY BEHIND THE TROUGH/COLD FRONT MOVING THROUGH THE REGION. WINDS ARE THEN EXPECTED TO REMAIN BELOW 20 KNOTS TUE NIGHT THROUGH THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...TITUS AVIATION...JLB MARINE...VOSS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
123 PM CDT SUN JUL 21 2013 .UPDATE... QUICK UPDATE TO ADJUST POPS FOR LATEST TRENDS...PRIMARILY TO RAISE TO LIKELY CATEGORY S AND E AS CONVECTION CONTINUE TO BUILD/PROPAGATE N ALONG N EDGE OF CONVECTIVE MASS TO OUR S. PER LAPS AND RUC ACTIVITY SHOULD BE BUILDING INTO A MORE UNSTABLE AIRMASS WITH MAX OF SBLI NEAR -8 OVER EC MS. HENCE EXPECT ACTIVITY TO BECOME A BIT MORE ROBUST WITH CONTINUED POTENTIAL FOR SOME STRONGER STORMS. && .PREV DISCUSSION... /ISSUED 1028 AM CDT SUN JUL 21 2013/ UPDATE... MAKING SOME ADJUSTMENTS TO THE FORECAST FOR THE FIRST COUPLE OF PERIODS...INCLUDING ADJUSTING POPS A LITTLE FOR TODAY...CUTTING POPS FOR TONIGHT...AND TWEAKING TEMPS UP A HAIR FOR THIS AFTERNOON. SHORT TERM... WATER VAPOR AND RUC STREAMLINE ANALYSIS SHOW REMNANT UPPER LEVEL LOW CURRENTLY OVER THE LOWER DELTA REGION. SHORT TERM MODELS SHOW THIS LOW OPENING UP AND DRIFTING EAST TODAY. BLENDED TOTAL PW PRODUCT SHOWS BEST DEEP MOISTURE OVER S/E AREAS AHEAD OF UPPER LOW...BUT EVEN RIGHT UNDER THE UPPER LOW WHERE A MIN IN MOISTURE EXISTS...PW VALUES STILL AROUND 1.8 INCHES. CU IS BEGINNING TO FORM ACROSS THE AREA...AND WITH CONTINUED HEATING AND SUPPORT FROM UPPER SYSTEM EXPECT CONVECTIVE COVERAGE TO INCREASE THROUGH THE AFTERNOON. SHORT TERM MESOSCALE MODELS AGREE ON BEST COVERAGE OVER S/E AREAS...AND THIS GENERALLY SEEMS SUPPORTED BY LATEST TRENDS IN OBSERVATIONAL DATA. DID TWEAK POPS UP A HAIR TO GET ALL AREAS TO AT LEAST 30 PCT BUT OVERALL TREND OF GOING FORECAST LOOKS OK. MORNING SOUNDING ANALYSIS AND LOCAL RUC MICROBURST PARAMETER SUGGEST THAT CURRENT WORDING IN HWO AND GRAPHICAST OF SOME STRONG STORMS SEEMS REASONABLE. RUC SHOWS 500 MB TEMPS COOLING A DEG OR TWO MOST OF AREA AS MID LEVEL COLD POOL WITH UPPER LOW MOVES ACROSS...AND THIS SHOULD HELP ENHANCE INSTABILITY AND LAPSE RATES A BIT. THUS WOULD CERTAINLY NOT RULE OUT A COUPLE OF SEVERE STORMS THIS AFTERNOON...PARTICULARLY WITH ANY CELL/BOUNDARY MERGERS. WITH PRETTY COMPLETE LACK OF CLOUDINESS BEFORE BUILDING CU...TEMPS HAVE WARMED QUITE QUICKLY THIS MORNING. ADJUSTED DIURNAL CURVE FOR MORE RAPID WARMUP AND TWEAKED MAXES UP A DEG OR TWO. WITH REGARD TO TONIGHT...THINKING THAT 00Z GFS MAY HAVE BEEN A WET ANOMALY BASED ON GEFS GUIDANCE...LATEST 06Z GFS...AND 00Z ECMWF. MAIN CONCERN FOR CONVECTION TONIGHT IS LIKELY WAVE THAT HAS BEEN PRODUCING SOME CONVECTION OVER NE OK THIS MORNING...AND IT IS CERTAINLY PLAUSIBLE THAT THIS SYSTEM COULD INCITE SOME OVERNIGHT CONVECTION ESPECIALLY OVER NORTHERN AREAS. HOWEVER...HIGH CHANCE TO CATEGORICAL POPS IN CURRENT FORECAST AS PROVIDED BY 00Z GFS SEEM A BIT BULLISH...AND WILL REDUCE POPS BY 15-30 PCT AREA WIDE FOR TONIGHT. && .AVIATION... VFR CONDITIONS WERE BEING OBSERVED AT 14Z AND WILL PREVAIL AT ALL SITES THROUGH 18Z. MODELS INDICATE GREATEST COVERAGE OF TSTMS THIS AFTN/EVNG WL BE ACROSS THE SRN HALF OF THE AREA. BRIEF IFR CONDITIONS CAN BE EXPECTED AROUND THE STORMS FROM 18Z-04Z. VFR CONDITIONS WL RESUME AREAWIDE THIS EVNG AND CONTINUE THROUGH 09Z MON. AFTER 09Z...MVFR VSBYS WL BE PSBL MAINLY ACROSS THE SRN HALF OF THE AREA. CONVECTION MAY GET AN EARLY START ACROSS THE NORTH MONDAY MORNING DUE TO A DISTURBANCE IN THE NW FLOW ALOFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 73 92 76 94 / 33 48 27 29 MERIDIAN 72 91 72 96 / 35 61 38 41 VICKSBURG 73 93 75 94 / 30 41 21 21 HATTIESBURG 72 92 74 95 / 29 60 34 31 NATCHEZ 73 91 75 92 / 31 41 21 17 GREENVILLE 73 94 75 95 / 34 41 31 24 GREENWOOD 72 93 75 95 / 40 48 40 32 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ AEG
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1154 AM CDT SUN JUL 21 2013 .AVIATION... 18Z TAFS FOR KOMA...KOFK...KLNK A SCT TO BKN CU FIELD IS EXPECTED AT OMA/LNK THIS AFTERNOON WITH A FEW CU AT OFK. THESE WILL LIKELY DISSIPATE QUICKLY THIS EVENING WITH JUST SOME SCT MID AND HIGH LEVEL CLOUDS EXPECTED OVERNIGHT. GIVEN THE INCREASE IN LOW-LEVEL MOISTURE WE MAY SEE SOME MVFR CIGS WITH HZ/BR AT OMA AROUND SUNRISE ON MONDAY BUT IF THIS OCCURS IT WILL BE SHORT LIVED. SFC CDFNT WILL BE MOVG TOWARD THE TAF SITES ON MONDAY BUT WON`T MAKE IT PRIOR TO 18Z WITH JUST A GENERAL SRLY/SWRLY SFC WIND EXPECTED THRU THE PERIOD. && .PREV DISCUSSION... /ISSUED 1019 AM CDT SUN JUL 21 2013/ UPDATE... UPDATED TO ADJUST MORNING AND AFTERNOON POPS DISCUSSION... 12Z UPPER AIR ANALYSIS INDICATED THAT A SEASONABLY STRONG SHORTWAVE TROUGH EXTNDD FM WRN MN INTO CNTRL NEB. THIS WAS SPREADING LARGE-SCALE ASCENT ACROSS THE FA THIS MORNING. THE 12Z KOAX RAOB INDCD AROUND 1400 J/KG OF MUCAPE WITH LITTLE CAPPING. THUS THE COMBINATION OF THE FORCING AND WEAKLY CAPPED ATMOSPHERE WAS LEADING TO SCT TSRA OVER FAR SE NEB AND SW IA. THIS SHOULD CONT TO SHIFT EWD THIS MORNING ASSOCIATED WITH THE SHORTWAVE TROUGH. WHAT HAPPENS IN THE WAKE OF THIS MORNING ACTIVITY IS A BIT UNCLEAR. MODIFYING THE 12Z SOUNDING YIELDS LITTLE CAPPING AS TEMPERATURES CLIMB INTO THE MID 80S WITH AROUND 2000 J/KG OF MLCAPE. THE NEGATIVE THOUGH IS THE SUBSIDENCE THAT WILL BE SPREADING INTO THE AREA LATER THIS MORNING IN THE WAKE OF THE MORNING SHORTWAVE TROUGH. THIS IS LIKELY TO COMBINE WITH A LACK OF A SFC BOUNDARY TO FOCUS CONVERGENCE TO MAKE REDEVELOPMENT THIS AFTERNOON PRETTY UNLIKELY. WILL MAINTAIN A SCHC OF AFTERNOON STORMS OVER THE ERN FA OTHERWISE WE FEEL IT WILL BE A PRETTY DRY AFTERNOON. THE OTHER ELEMENTS OF THE FORECAST APPEAR ON TRACK ATTM. PREV DISCUSSION... /ISSUED 301 AM CDT SUN JUL 21 2013/ DISCUSSION... FORECASTING AREAL EXTENT OF CONVECTION THROUGH THE FORECAST WILL BE A SIGNIFICANT CHALLENGE AS THE REGION REMAINS IN NORTHWEST FLOW THIS WEEK. FIRST ROUND OF CONVECTION IS MOVING INTO EASTERN NEBRASKA EARLY THIS MORNING...BUT WILL ALSO HAVE TO OVERCOME A POCKET OF DRY AIR AT H85. CONTINUED THETAE ADVECTION SHOULD HELP TO ERODE THIS DRY POCKET AND CONTINUE TRIGGER STORMS THIS MORNING THAT WILL CONTINUE TO MOVE EASTWARD THROUGH THE AREA INTO WESTERN IOWA BEFORE DISSIPATING THROUGH MID TO LATE MORNING. WHILE HEAVY RAINS ARE NOT WIDESPREAD...SOME VERY SPOTTY LOCATIONS WHERE LIGHTNING IS OCCURRING ARE LIKELY PICKING UP SOME DECENT MEANINGFUL RAINFALL. MEANWHILE...WATER VAPOR IMAGERY INDICATES ANOTHER SUBTLE WAVE IS LIKELY MOVING THROUGH WESTERN SOUTH DAKOTA. ANOTHER CLUSTER OF STORMS HAS REFIRED ACROSS THAT AREA...MOVING INTO NORTH CENTRAL NEBRASKA. BOTH THE NAM AND RAP SEEM TO HAVE PICKED UP ON THIS FEATURE AND MOVE IT THROUGH THE FORECAST AREA THIS AFTERNOON...WHICH COULD BE THE TRIGGER FOR ADDITIONAL STORMS AS WE HEAD THROUGH PEAK HEATING. FORWARD SPEED SUGGESTS THAT THIS MAY MOSTLY BE OUT OF THE AREA BY EARLY THIS EVENING. THE REMAINDER OF SUNDAY NIGHT AND MONDAY MORNING SHOULD BE DRY. A FRONTAL BOUNDARY MOVING INTO THE REGION COULD TRIGGER ISOLATED AFTERNOON STORMS IN NORTHEAST NEBRASKA. TEMPS AHEAD OF THE FRONT WILL PROBABLY REACH THE LOWER 90S ONCE AGAIN. SHOULD ALSO SEE A CHANCE OF THUNDERSTORMS MONDAY NIGHT AS THE FRONT MOVES THROUGH THE AREA. THE NEXT WAVE APPEARS ON THE HORIZON BY TUESDAY AFTERNOON THEN MOVES THROUGH THE REGION TUESDAY NIGHT. WEDNESDAY AND WEDNESDAY NIGHT SHOULD BE DRY...BUT ANOTHER WAVE MOVES INTO THE AREA ON THURSDAY AND LINGERS THROUGH FRIDAY. THE GFS SUGGESTS THAT WE MIGHT REMAIN DRY ON SATURDAY...BUT THE ECMWF HAS YET ANOTHER SURGE OF MOISTURE MOVING THROUGH. NEVERTHELESS...CONFIDENCE DECREASES IN SPECIFICS TOWARD THE END OF THE WEEK. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT SUN JUL 21 2013 .SYNOPSIS... A SURFACE TROUGH WILL PERSIST OVER THE REGION...IN A MOIST AIR MASS...AT LEAST THROUGH THE MIDDLE OF THE WEEK...AS A TROUGH IN THE UPPER LEVELS OF THE ATMOSPHERE MOVES INTO THE MID ATLANTIC AND THE CAROLINAS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 310 PM SUNDAY... THE LATEST SURFACE ANALYSIS CONTINUED TO SHOW THE SURFACE TROUGH OVER THE NORTHWEST PIEDMONT TOWARD THE UPSTATE OF SOUTH CAROLINA... AND ALONG THIS TROUGH WHERE BETTER SURFACE CONVERGENCE EXISTED...SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING OR DEVELOPING. DOWNDRAFT CAPE AND LOW-LEVEL SHEAR REMAINED LIMITED... BUT THE LATEST SPC MESOANALYSIS SHOWED MIXED-LAYER CAPE AROUND 2000J/KG NEAR THE SURFACE TROUGH. SCATTERED SHOWERS AND THUNDERSTORMS SHOULD CONTINUE TO MOVE INTO THE WESTERN PIEDMONT DURING THE LATE AFTERNOON...AND THE HRRR WRF HAS BEEN CONSISTENT SHOWING SCATTERED SHOWERS AND THUNDERSTORMS SPREADING EAST TO ABOUT U.S. 1 THROUGH 01Z BEFORE GENERALLY DIMINISHING. THROUGHOUT THE DAY...THE RUC HAS BEEN PERSISTENT MAINTAINING SOME CHANCES FOR SHOWERS ACROSS THE SANDHILLS AND CENTRAL AND SOUTHERN COASTAL PLAIN...WHERE THE GFS HAS SLIGHTLY GREATER 850MB LIFT OVERNIGHT AND WHERE THAT MODEL ALSO FORECASTS A RELATIVE MAXIMUM OF POTENTIAL VORTICITY MOVING ACROSS THE AREA. GIVEN THIS...IT IS POSSIBLE THAT SOME OF THE SHOWERS OVER WESTERN NORTH CAROLINA OR THE UPSTATE OF SOUTH CAROLINA WILL PERSIST AS THEY DRIFT EAST NEAR AND JUST NORTH OF THE SOUTH CAROLINA BORDER OVERNIGHT. WILL KEEP A SLIGHT CHANCE OF SHOWERS FOR THE OVERNIGHT HOURS AFTER MIDNIGHT MAINLY EAST OF A LINE FROM ABOUT KRWI TO KFAY. UNDER A PARTLY-TO-MOSTLY CLOUDY SKY...WITH AREAS OF CLOUDS COURTESY OF DEEP CONVECTION AND THEN SOME HIGH CLOUDS MOVING IN FROM THE WEST LATE...OVERNIGHT LOWS WILL AGAIN BE 70 TO 75 DEGREES. THE SREF SHOWS THE POTENTIAL FOR LOW CLOUDS TO BE LESS THAN THE LAST COUPLE OF MORNINGS...HOWEVER...SOME OF THE GUIDANCE MAINTAINS THE CHANCES FOR LOW CLOUDS PARTICULARLY TOWARD KRDU...KFAY...AND KRWI...LESS TOWARD THE TRIAD. IF LOW CLOUDS INDEED OCCUR...IT IS CURRENTLY THOUGHT THEY SHOULD BE LESS WIDESPREAD THAN WHAT HAS OCCURRED THIS WEEKEND. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 310 PM SUNDAY... MONDAY AND MONDAY NIGHT... BOTH THE NAM AND THE GFS GRADUALLY MOVE THE WEAK UPPER LOW OVER THE SOUTHERN MISSISSIPPI RIVER SLOWLY NORTHEAST...AND INDEED THE LATEST WATER VAPOR IMAGERY SHOWS THIS WEAK LOW MOVING MORE INTO MISSISSIPPI. BY THE TIME THE UPPER LOW GETS TO CENTRAL NORTH CAROLINA...IT IS FORECAST TO WEAKEN FURTHER...AND FORECAST PARAMETERS OF INSTABILITY...SHEAR...AND MOISTURE ARE SIMILAR TO WHAT HAS RECENTLY OCCURRED. 850MB THETA-E IS PERSISTENT AROUND 340K AS WELL...CURRENTLY SUGGESTIVE OF LITTLE OVERALL CHANGE IN ANTICIPATED CONDITIONS. WITH THE WEAK UPPER LOW THE GFS DOES FORECAST A VERY MODEST 35KT JETLET INTO CENTRAL NORTH CAROLINA AT 300MB MONDAY AFTERNOON...BUT WITH MIXED-LAYER CAPE FROM ABOUT 1000J/KG TO 2000J/KG AND DOWNDRAFT CAPE REMAINING 500J/KG OR LESS...THINK CONDITIONS WILL BE SIMILAR TO THE LAST COUPLE OF DAYS...MOSTLY SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...HIGHER CHANCES RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA TOWARD THE WESTERN PIEDMONT AS THE WEAK LOW OR ITS REMNANTS APPROACHES...AND A PARTLY SUNNY DAY ON AVERAGE WITH HIGHS AROUND 90. MONDAY NIGHT...BOTH THE NAM AND THE GFS FORECAST ALMOST A WEAK PSEUDO FRONT OR STRONG TROUGH MOVING INTO THE WESTERN PART OF CENTRAL NORTH CAROLINA WITH DIMINISHING PRECIPITABLE WATER VALUES BEHIND IT TO NEAR 1.5 INCHES LATE TOWARD THE YADKIN RIVER AND DEW POINTS FALLING INTO THE UPPER 60S. BUFR SOUNDINGS BECOME SOMEWHAT MORE STABLE OVERNIGHT IN CENTRAL NORTH CAROLINA...AND QPF IS CERTAINLY LIMITED...BUT WITH THE APPROACH OF THIS TROUGH WILL MAINTAIN A SLIGHT CHANCE OF A SHOWER THROUGH THE OVERNIGHT HOURS. OVERNIGHT LOWS ABOUT A DEGREE OR TWO COOLER THAN WHAT SHOULD OCCUR TONIGHT...BUT STILL 70 TO 75...MAYBE AN UPPER 60S LOW OR TWO TOWARD THE FAR WESTERN PIEDMONT. -DJF TUESDAY THROUGH WEDNESDAY NIGHT... HEIGHTS WILL CONTINUE TO SLOWLY FALL ALOFT TUESDAY AND WEDNESDAY AS A BROAD TROUGH BECOMES ESTABLISHED OVER THE EASTERN US. MEANWHILE...A COLD FRONT TO OUR NORTH WILL SLOWLY SINK SOUTHEAST AND EVENTUALLY MERGE WITH RELATIVELY STRONG LARGE SCALE LOW LEVEL TROUGH EAST OF THE MOUNTAINS. ENERGY CURRENTLY MOVING OUT OF MONTANA/WYOMING IS FORECAST MOVE THROUGH THE BASE OF THE UPPER TROUGH TUESDAY...FOLLOWED BY ANOTHER SHORTWAVE ON WEDNESDAY. HOWEVER...THE TIMING AND STRENGTH OF THESE WEAK WAVES AND OTHER DISTURBANCES WITHIN THE FLOW ARE STILL NEBULOUS. FORECAST SOUNDINGS DO INDICATE A BIT MORE WESTERLY FLOW ON TUESDAY...WITH PW TEMPORARILY DROPPING TO 1.5" OR LESS OVER THE WESTERN CWA AND THE INTRUSION OF DRIER MID LEVEL AIR. HOWEVER...WITH THE MEAN TROUGH AXIS STILL WEST OF OUR AREA... PROFILES MOISTEN BACK UP ON WEDNESDAY WITH MORE ENERGY APPROACHING FROM THE WEST. UNDER CYCLONIC FLOW ALOFT AND MODERATE INSTABILITY...WE SHOULD SEE SCATTERED STORMS BOTH DAYS BUT BETTER COVERAGE OVER THE EAST IN THE VICINITY OF BETTER LOW LEVEL CONVERGENCE AND DEEP MOISTURE. HIGHS 88-92. LOWS IN UPPER 60S AND LOWER 70S. -BLS && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 310 PM SUNDAY... THE LAST IN A SERIES OF UPPER DISTURBANCES IS FORECAST TO PASS THROUGH THE UPPER TROUGH ON THURSDAY...WITH MODELS HAVING TRENDED DRIER FRIDAY AND SATURDAY AS THE REMNANT FRONTAL ZONE OVER THE EAST COAST STATES SLIDES LITTLE FURTHER EAST TOWARD THE COAST. THERE SHOULD BE LESS COVERAGE IF STORMS THURSDAY AS THE MID LEVELS BEGIN TO DRY OUT...BUT THE PASSAGE OF THE MEAN TROUGH AXIS AND SLIGHTLY STRONGER MID-LEVEL FLOW MAY STILL SUPPORT SOME STRONG TO SEVERE STORMS. LOWER DEWPOINTS BEHIND THE FRONT/TROUGH SHOULD LIMIT CONVECTION FRIDAY AND SATURDAY...PARTICULARLY IN THE WEST. THICKNESSES FALL AS WELL...WITH HIGHS LIKELY TO BE MORE IN THE MID AND UPPER 80S. THE BROAD EASTERN US TROUGH IS EXPECTED TO RELOAD BY THE END OF THE WEEKEND AS ENERGY CONTINUES TO ROTATE AROUND AN UPPER LOW NORTH OF THE HUDSON BAY. BOTH THE ECMWF AND GFS SHOW A MODEST LOW PRESSURE SYSTEM MOVING OFF THE FRONT RANGE SATURDAY AND MOVING TOWARD THE MID-ATLANTIC STATES BY SUNDAY/MONDAY...THOUGH WPC/S EXTENDED DISCUSSION RAISES SOME DOUBT IN THE STRENGTH OF SUCH A FEATURE. NONETHELESS...THERE IS ENOUGH AGREEMENT IN THE MODELS TO HAVE MEDIUM CONFIDENCE IN TEMPS SLIGHTLY BELOW NORMAL OVER THE WEEKEND AND ANOTHER CHANCE OF STORMS BY THE END OF THE WEEKEND. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 145 PM SUNDAY... PERSISTENCE CONTINUES OVERALL THROUGH THE 18Z VALID TAF PERIOD. SHOWERS AND THUNDERSTORMS MOSTLY IN A SCATTERED NATURE WILL OCCUR WITH THE BETTER CHANCES EARLY IN THE TAF PERIOD TOWARD KGSO AND KINT. OVERNIGHT...MODELS SHOW LIFT IS BETTER TOWARD THE SANDHILLS AND SOUTHERN COASTAL PLAIN WHICH MAY KEEP A FEW SHOWERS GOING PRIMARILY TOWARD KFAY AND JUST SOUTH OF KRWI. GUIDANCE OVERALL SHOWS THE PROBABILITY OF LATE NIGHT AND EARLY MONDAY MORNING LOW CLOUDS TO BE LESS THAN SATURDAY AND THIS SUNDAY MORNING. HOWEVER...INCLUDED LOW CLOUDS FROM ABOUT 10Z TO 14Z AT KRDU...KFAY...AND KRWI WHERE THE CHANCES RELATIVE TO THE TRIAD TAFS ARE GREATER. IT IS POSSIBLE THAT ANY LOW CLOUDS THAT DEVELOP LATE TONIGHT ARE MORE SPOTTY IN COVERAGE AS OPPOSED TO THE MORE WIDESPREAD COVERAGE THAT HAS OCCURRED OVER THE WEEKEND. BEYOND THE 18Z VALID TAF PERIOD...AVIATION INTERESTS SHOULD CONTINUE TO BE PREPARED FOR GENERALLY SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...AND THEIR ASSOCIATED SUB-VFR CONDITIONS. CHANCES OF THESE SHOWERS AND THUNDERSTORMS MAY SHIFT FROM BEING GREATER TOWARD THE TRIAD TAFS MONDAY TO BEING GREATER EAST FOR THE MIDDLE AND END OF THE WEEK. BASED ON THE LATEST FORECAST GUIDANCE...THE NEXT DAY WITH THE POTENTIAL FOR MORE WIDESPREAD LOW CLOUDS IN THE EARLY MORNING HOURS IS THURSDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF/BLS LONG TERM...BLS AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
146 PM EDT SUN JUL 21 2013 .SYNOPSIS... A SURFACE TROUGH WILL PERSIST OVER THE REGION...IN A MOIST AIR MASS...AT LEAST THROUGH THE MIDDLE OF THE WEEK...AS A TROUGH IN THE UPPER LEVELS OF THE ATMOSPHERE MOVES INTO THE MID ATLANTIC AND THE CAROLINAS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1035 AM SUNDAY... THE LATEST SURFACE ANALYSIS CONTINUED TO SHOW A WEAK GRADIENT OVER CENTRAL NORTH CAROLINA...WITH A PERSISTENT SURFACE TROUGH WEST OF THE YADKIN RIVER. THE MORNING UPPER-LEVEL ANALYSES SHOWED A FAIRLY PRONOUNCED 850MB TROUGH OVER CENTRAL NORTH CAROLINA...CAPTURED BY THE RUC AND FORECAST TO LINGER OVER THE AREA WHILE WEAKENING THROUGH THE AFTERNOON. ON WATER VAPOR...IT SEEMED AS IF CENTRAL NORTH CAROLINA WAS IN ALMOST SUBTLE RIDGING BETWEEN A WEAK UPPER LOW OVER THE SOUTHERN MISSISSIPPI RIVER AND A WEAK WAVE MOVING EAST ACROSS THE STATE. IT WAS INTERESTING TO NOTE THAT THE PRECIPITABLE WATER VALUE ON THE KRNK SOUNDING WAS BELOW 1.4 INCHES THIS MORNING. IT WAS HIGHER AT KGSO COMPARED TO 12Z SATURDAY. DOWNDRAFT CAPE ON THE SPC MESOANALYSIS WAS WEAKER THAN SATURDAY...AND OTHER PARAMETERS SUCH AS THE MID-LEVEL LAPSE RATES AND THETA-E DIFFERENCE ALOFT WERE SLIGHTLY LESS AS WELL. THE LATEST RUC FORECASTS NOTICEABLE 850MB SUBSIDENCE OVER CENTRAL NORTH CAROLINA FOR THE AFTERNOON...WITH SOMEWHAT BETTER LIFT MOVING IN OVER THE NORTHWEST PIEDMONT AND THE SANDHILLS LATE TODAY AND THIS EVENING. MOST OF THE CONVECTIVE-ALLOWING MODELS DEVELOP SCATTERED SHOWERS AND THUNDERSTORMS OVER CENTRAL NORTH CAROLINA THIS AFTERNOON...AND FOR THE MID-MORNING UPDATE OPTED TO CONCENTRATE THE BETTER CHANCES OVER THE NORTHWEST PIEDMONT...NEAR WHAT MAY END UP BEING SOME DIFFERENTIAL HEATING BASED ON THE LATEST VISIBLE IMAGES. A STORM OR TWO COULD BECOME STRONG...BUT THE PREPONDERANCE OF THE CURRENT EVIDENCE SUGGESTS THE POTENTIAL FOR A SEVERE STORM IS LIMITED. WILL REVIEW LATER DATA TO TRY TO FOCUS BETTER CHANCES FOR THIS EVENING... AS BASED ON THE LATEST RUC THIS WOULD BE MAINLY NORTH OF U.S. 64 AND OVER THE SANDHILLS WHERE THE GREATER 850MB LIFT IS CONCENTRATED. KEPT HIGH TEMPERATURES AS IS GIVEN AT LEAST SOME EXPECTED SUN... THOUGH HIGHS ARE FORECAST BELOW FULL SUN 1000-850MB THICKNESS VALUES WHICH WOULD SUGGEST HIGHS A CATEGORY WARMER. LOWS TONIGHT IN THE LOWER 70S. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 300 AM SUNDAY... WEAK SHORT-WAVE ENERGY CURRENTLY OVER THE NORTHERN PLAINS WILL UNDERGO SLIGHT AMPLIFICATION(ALONG WITH AMPLIFICATION OF THE LONG WAVE TROUGH AS WELL)AS IT PROGRESSES EAST-SOUTHEASTWARD INTO THE OHIO AND TN VALLEY ON MONDAY...REACHING THE CENTRAL-SOUTHERN BY DAYBREAK TUESDAY. IN RESPONSE TO THE ATTENDANT UPSTREAM HEIGHT FALLS ON THE ORDER OF 20 TO 30 METERS...A WEAK WAVE OF LOW PRESSURE IS FORECAST TO DEVELOP ALONG THE SURFACE TROUGH OF LOW PRESSURE BISECTING THE VIRGINIAS AND CAROLINAS...WHICH WILL SERVE TO STRENGTHEN THE LOW-LEVEL MOISTURE CONVERGENCE AS A POOL OF +2.0 PWATS RESIDES OVER THE SOUTHEASTERN STATES. ADDITIONALLY...THERE IS ALSO THE POTENTIAL THAT REMNANT CENTER ASSOCIATED WITH THE WEAK UPPER LOW CURRENTLY OVER LOUISIANA COULD MOVE NORTHEASTWARD OVER THE AREA LATE MONDAY AND INTO MONDAY NIGHT...FURTHER AUGMENTING ASCENT OVER THE AREA. AS SUCH...CONVECTION MONDAY AFTERNOON IS EXPECTED TO BE MORE ROBUST THAN IN PREVIOUS DAYS...WITH THE THREAT OF CONVECTION PERSISTING THROUGH THE OVERNIGHT HOURS. CONFIDENCE IN THE TIMING/IMPACTS OF THIS DISTURBANCE IS LOW AT THIS POINT...ESPECIALLY WITH THE 00Z/21 GFS COMPLETELY SHEARING THE DISTURBANCE COMPLETING APART OVER GEORGIA/SC. HOW THIS FEATURES EVOLVES WILL LIKELY BE THE DIFFERENCE BETWEEN LIKELY OR CHANCE POPS ACROSS CENTRAL NC MONDAY AFTERNOON/EVENING. HIGH +2.0 PWATS COULD RESULT IN ONE OR TWO WET MICROBURSTS...MAINLY DURING PEAK AFTERNOON HEATING/DESTABILIZATION...WITH A MORE ORGANIZED SEVERE THREAT BEING IMPEDED BY WEAK SHEAR AND WEAK MID-LEVEL LAPSE RATES. ALSO...WITH LOCAL RIVER....STREAMS AND CREEKS STILL RUNNING HIGH...FLASH FLOODING WILL ALSO BE POSSIBLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 245 AM SUNDAY... TUESDAY AND TUESDAY NIGHT: WITH THE PERSISTENT SOUTHWEST FLOW...THE ATMOSPHERE WILL REMAIN SUFFICIENTLY MOIST AND UNSTABLE. THE SURFACE TROUGH IS EXPECTED TO STALL OVER THE MID ATLANTIC...WITH THE UPPER LEVEL TROUGH SLOWLY DRIFTING EAST OVER THE AREA. THE 00Z RUN OF THE GFS PICKS UP ON A H3 DISTURBANCE MOVING THROUGH NC TUESDAY AFT/EVE...WHICH SHOULD HELP ENHANCE THE DIURNALLY DRIVEN CONVECTION. BEST LIFT WILL TRANSLATE FROM NW TO SE THROUGH CENTRAL NC AHEAD OF THE BACKDOOR COLD FRONT...WHICH WPC PREDICTS WILL MOVE TROUGH THE AREA TUESDAY NIGHT AND INTO WEDNESDAY...POTENTIALLY STALLING ALONG THE COAST. AS SUCH...WILL SHOW BEST CHANCES FOR CONVECTION FROM THE TRIANGLE SE BETWEEN 18Z TUESDAY AND 06Z WEDNESDAY. HIGH TEMPS IN THE UPPER 80S TO LOW 90S AND OVERNIGHT LOWS IN THE LOW TO MID 70S EXPECTED. WEDNESDAY THROUGH SATURDAY: LOW LEVEL WINDS MAY TEMPORARILY BECOME MORE WNW BEHIND THE BACKDOOR FRONT SHOULD IT INDEED MOVE THROUGH THE AREA AND STALL ALONG THE COAST BY WEDNESDAY...WHICH WOULD YIELD A SUBSEQUENT DRYING OF THE MID LEVELS. CURRENT MODEL AGREEMENT WITH REGARD TO THE TROUGH...AT BOTH THE SURFACE AND ALOFT...LINGERING OVER THE AREA THROUGH THE END OF THE WEEK IS GOOD. THE LOCATION OF THE TROUGH AXIS WILL PLAY A ROLE IN WHERE THE BEST MOISTURE IS AVAILABLE...WHICH CURRENTLY IS EXPECTED ALONG THE COAST. DEPENDING ON THEIR TIMING...A SERIES OF UPPER LEVEL DISTURBANCES MOVING OVER THE AREA COULD ENHANCE DIURNAL CONVECTIVE ACTIVITY THROUGH THE PERIOD. OF LESSER CERTAINTY IS THE COVERAGE AND LOCATION OF THE ANTICIPATED AFT/EVE SHOWERS AND STORMS. FOR NOW WILL CONTINUE TO INDICATE BEST PRECIP CHANCES DURING THE AFT/EVE HOURS ACROSS THE AREA...WITH SLIGHTLY HIGHER CHANCES ACROSS THE EAST WHERE THE BEST MOISTURE IS EXPECTED. ONLY SMALL CHANGES IN TEMPS FROM DAY TO DAY THROUGH THE PERIOD...HIGHS MAINLY IN THE MID 80S TO AROUND 90 DEGREES WITH OVERNIGHT LOWS MAINLY IN THE UPPER 60S TO LOW 70S. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 145 PM SUNDAY... PERSISTENCE CONTINUES OVERALL THROUGH THE 18Z VALID TAF PERIOD. SHOWERS AND THUNDERSTORMS MOSTLY IN A SCATTERED NATURE WILL OCCUR WITH THE BETTER CHANCES EARLY IN THE TAF PERIOD TOWARD KGSO AND KINT. OVERNIGHT...MODELS SHOW LIFT IS BETTER TOWARD THE SANDHILLS AND SOUTHERN COASTAL PLAIN WHICH MAY KEEP A FEW SHOWERS GOING PRIMARILY TOWARD KFAY AND JUST SOUTH OF KRWI. GUIDANCE OVERALL SHOWS THE PROBABILITY OF LATE NIGHT AND EARLY MONDAY MORNING LOW CLOUDS TO BE LESS THAN SATURDAY AND THIS SUNDAY MORNING. HOWEVER...INCLUDED LOW CLOUDS FROM ABOUT 10Z TO 14Z AT KRDU...KFAY...AND KRWI WHERE THE CHANCES RELATIVE TO THE TRIAD TAFS ARE GREATER. IT IS POSSIBLE THAT ANY LOW CLOUDS THAT DEVELOP LATE TONIGHT ARE MORE SPOTTY IN COVERAGE AS OPPOSED TO THE MORE WIDESPREAD COVERAGE THAT HAS OCCURRED OVER THE WEEKEND. BEYOND THE 18Z VALID TAF PERIOD...AVIATION INTERESTS SHOULD CONTINUE TO BE PREPARED FOR GENERALLY SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...AND THEIR ASSOCIATED SUB-VFR CONDITIONS. CHANCES OF THESE SHOWERS AND THUNDERSTORMS MAY SHIFT FROM BEING GREATER TOWARD THE TRIAD TAFS MONDAY TO BEING GREATER EAST FOR THE MIDDLE AND END OF THE WEEK. BASED ON THE LATEST FORECAST GUIDANCE...THE NEXT DAY WITH THE POTENTIAL FOR MORE WIDESPREAD LOW CLOUDS IN THE EARLY MORNING HOURS IS THURSDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...CBL/DJF SHORT TERM...CBL LONG TERM...KMC AVIATION...DJF
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
303 PM CDT SUN JUL 21 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 303 PM CDT SUN JUL 21 2013 MAIN CHALLENGE CONTINUES TO BE TSTM CHANCES AND SEVERITY FOR TONIGHT. LATEST MODEL GUIDANCE CONTINUES TO SUPPORT A THREAT FOR PORTIONS OF THE FA BUT EARLY ON MAINLY FOR THE KDVL REGION AS IT SHOULD TAKE A WHILE TO REACH THE RED RIVER VALLEY. CURRENTLY HAVE A COLD FRONT WORKING INTO FAR NORTHWEST ND WITH AN AREA OF LOW PRESSURE THERE AS WELL. A WARM FRONT EXTENDS SE FROM THIS LOW DOWN TO NEAR KBIS AND KABR. IN THIS WARM SECTOR DEW POINTS ARE GENERALLY IN THE LOW TO MID 60S WITH TEMPS IN THE 80S. EAST OF THE WARM FRONT DEW POINTS HAVE BEEN SLOW TO RECOVER FROM MORNING LOWS WITH 50S STILL COMMON. THERE HAS BEEN A WEAK TSTM COMPLEX OVER SOUTHWEST MANITOBA RIDING AHEAD OF THE MAIN SHORT WAVE. THIS SHOULD GET INTO THE FAR NW FA IN THE NEXT HOUR OR SO. INSTABILITY IS WEAK OUT AHEAD OF THIS INITIAL COMPLEX BUT IT MAY CONTINUE TO MOVE EAST ALONG THE BORDER WITH THE UPPER JET DYNAMICS IN PLACE. THE SEVERE THREAT SHOULD BE BEHIND THIS COMPLEX CLOSER TO THE COLD FRONT AND SFC LOW OVER WESTERN ND. INSTABILITY IS BETTER HERE WITH THE ABOVE MENTIONED WARMER AND MOIST AIR. THE MAIN SHORT WAVE ENERGY APPEARS TO BE LOCATED OVER SOUTHERN ALBERTA WHICH IS NEARING THE SFC BOUNDARY. WITH THE WAVE AND THE UPPER JET ENERGY A MORE ORGANIZED TSTM COMPLEX IS EXPECTED TO GET UNDERWAY OUT WEST. SPC HAS ISSUED MCD 1456 AND A NEW TORNADO WATCH FOR PORTIONS OF WESTERN AND CENTRAL ND. THERE HAVE BEEN A COUPLE OF CELLS THAT HAVE POPPED UP NEAR KISN THAT MAY BE THE START OF SOME STRONGER CELLS. NOT EXPECTING ANY STRONG STORMS TO APPROACH OUR WESTERN FA FOR A FEW MORE HOURS YET SO WE WILL HAVE TIME TO WATCH AND SEE HOW THINGS DEVELOP. LATEST RAP BRINGS SOME STORMS INTO OUR WESTERN FA IN THE 01-02Z MON TIME FRAME. NSSL WRF IS A LITTLE FASTER AND AS MENTIONED IN AN EARLIER AFD UPDATE IT DID BRING TSTMS A LOT FURTHER SOUTH THAN WHAT IS ANTICIPATED. FOLLOWED MORE CONTINUITY AND KEPT HIGHER PCPN CHANCES ACROSS THE NORTHERN HALF OF THE FA TONIGHT WITH LOWER CHANCES ACROSS THE SOUTH. THE COMBINATION OF THE LOW LEVEL JET UPPER JET AND THE WAVE SHOULD KEEP SHOWERS AND TSTMS GOING AFTER DARK JUST NOT SURE HOW LONG THE SEVERE POTENTIAL WILL GO. LEFT SOME LINGERING LOW PCPN CHANCES ACROSS THE EAST ON MONDAY MORNING WITH DRYING ACROSS THE WEST. SHOULD BE A FAIRLY NICE DAY WITH DRIER AIR MOVING BACK IN WITH NORTHWEST WINDS. MON NIGHT WILL BE A LITTLE COOL AGAIN ESPECIALLY ACROSS THE NORTH. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 303 PM CDT SUN JUL 21 2013 SHOULD REMAIN DRY TUE WITH FAIRLY LIGHT WINDS DUE TO THE PROXIMITY OF THE SFC HIGH. CHANCES FOR PCPN RETURN BY TUE NIGHT AND WED ALTHOUGH MODELS NOT IN VERY GOOD AGREEMENT ON THE DETAILS. WEDNESDAY NIGHT-SUNDAY...12Z MODELS MAINTAIN SIMILAR IDEA AS PREVIOUS RUNS. NORTHWEST FLOW ALOFT INTO FRIDAY WITH UPPER RIDGING BUILDING INTO THE REGION FOR THE WEEKEND. THERE WILL BE SLIGHT THUNDERSTORM CHANCES WITH ANY UPPER WAVE WITHIN THE NORTHWEST FLOW ALOFT...WITH THESE CHANCES ENDING ONCE THE RIDGING BUILDS INTO THE REGION. TEMPERATURES NEAR OR SLIGHTLY BELOW NORMAL VALUES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1249 PM CDT SUN JUL 21 2013 THE MAIN CONCERN WILL BE TIMING OF THUNDERSTORMS. LATEST MODEL GUIDANCE IN LINE WITH PREVIOUS THINKING AND NOT MUCH CHANGE NEEDED TO PREVIOUS TAFS. ANTICIPATE A LINE OF STORMS TO MOVE INTO NORTHEAST NORTH DAKOTA AROUND 00Z...AND INTO THE NORTHERN VALLEY AROUND 02Z...CONTINUING TO THE EAST. STILL NOT A LOT OF CONFIDENCE WITH HOW FAR SOUTH THUNDER CHANCES WILL BE AND LEFT OUT OF THE KFAR FORECAST (COVERAGE WILL BE SIGNIFICANTLY LESS TO THE SOUTH). SOUTHERLY WINDS WILL SHIFT TO THE WEST/NORTHWEST TONIGHT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...GODON LONG TERM...GODON/TG AVIATION...TG
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1113 AM CDT SUN JUL 21 2013 .UPDATE... AN UPPER TROF IS BEGINNING TO PUSH INTO THE MIDSOUTH THIS MORNING. LATEST MODELS INDICATE CHANCES FOR CONVECTION WILL MAINLY COME FROM DIURNAL BASED STORMS THIS AFTERNOON. ALTHOUGH...A MINOR SHORTWAVE WILL PUSH INTO NORTHEAST ARKANSAS LATE THIS AFTERNOON WHICH COULD INCREASE COVERAGE. THE SHORTWAVE PRODUCED CONVECTION ACROSS SE KANSAS AND NE OKLAHOMA OVERNIGHT. THE COMPLEX HAS SINCE DIED OVER NW ARKANSAS. THIS IS A LOT QUICKER THAN WHAT THE LATEST HRRR HAS SHOWN. THERE MAY BE SOME REDEVELOPMENT THIS AFTERNOON THUS WILL KEEP 50-60 POPS ACROSS NE ARKANSAS OTHERWISE WILL REDUCE CHANCES ACROSS THE REST OF THE CWA TO 30S. KRM && .DISCUSSION... /ISSUED 424 AM CDT SUN JUL 21 2013/ A WET WEATHER PATTERN WAS BEGINNING TO TAKE SHAPE ACROSS THE MIDSOUTH THAT WILL LEAD TO SEVERAL DAYS WITH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. BY THURSDAY...MANY LOCATIONS ARE EXPECTED TO HAVE RECEIVED TWO OR THREE OF RAIN...LOCALLY MORE. EARLY THIS MORNING...A NEARLY STATIONARY FRONT STRETCHED TO THE NORTH OF THE MIDSOUTH FROM CENTRAL MO TO SOUTHERN IN. OUTFLOW BOUNDARIES FORMED IN ASSOCIATION WITH THUNDERSTORMS THAT DEVELOPED SOUTH OF THIS FRONT WITH THESE BOUNDARIES PUSHING INTO EAST AR AND NORTHWEST TN LAST EVENING. THIS SPARKED SCATTERED THUNDERSTORMS IN PORTIONS OF THIS REGION DURING THE NIGHT BUT MOST HAVE NOW DISSIPATED. A FEW SHOWERS AND THUNDERSTORMS DEVELOPED EARLY THIS MORNING ACROSS PORTIONS OF NORTHEAST MS DUE TO A WEAK BUT LARGE LOW PRESSURE SYSTEM ALOFT CENTERED ALONG THE NORTHEAST LA / CENTRAL MS BORDER. SEVERAL FACTORS WILL LEAD TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE MIDSOUTH TODAY AND TONIGHT. AN UPPER LEVEL SHORT WAVE WILL PUSH TOWARD THE MIDSOUTH FROM THE NORTHWEST WITH UPPER LEVEL HEIGHTS CONTINUING TO DECREASE TO UNSEASONABLY LOW VALUES ACROSS THE MIDSOUTH. THE UPPER LEVEL LOW TO OUR SOUTH WILL PUSH EAST NORTHEASTWARD TO JUST SOUTH OF NORTHEAST MS. A MOIST AND UNSTABLE ATMOSPHERE WILL EXIST ACROSS THE MIDSOUTH. A FEW STRONG THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND TONIGHT WITH WEAK MID LEVEL LAPSE RATES LIMITING THE THREAT FOR SEVERE THUNDERSTORMS. WINDS GUSTS TO NEAR 50 MPH...SMALL HAIL...AND HEAVY RAINFALL WITH LOCALIZED FLASH FLOODING MAY OCCUR. PRECIPITABLE WATER VALUES WILL INCREASE TO BETWEEN 2 AND 2.25 INCHES ALONG AND WEST OF THE MS RIVER. UPPER LEVEL HEIGHTS WILL CONTINUE TO LOWER ACROSS THE MIDSOUTH TONIGHT AS THE SHORT WAVE EMBEDDED IN A BROAD UPPER LEVEL TROUGH MOVES INTO THE MIDSOUTH RESULTING IN NUMEROUS SHOWERS AND THUNDERSTORMS. ON MONDAY...AN LARGE UPPER LEVEL TROUGH WILL DEEPEN OVER THE EASTERN UNITED STATES. MID LEVEL LAPSE RATES WILL DECREASE ACROSS THE MIDSOUTH LEADING TO INCREASED INSTABILITY. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE REGION. THIS WILL PLAY HAVOC WITH HIGH TEMPERATURES SINCE IT IS DIFFICULT TO DETERMINE HOW HOT IT WILL GET BEFORE THE SHOWERS AND STORMS DEVELOP. A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE MONDAY NIGHT AND TUESDAY AS UPPER LEVEL SHORT WAVES EMBEDDED IN NORTHWEST FLOW ALOFT CONTINUE TO INTERACT WITH A MOIST AND UNSTABLE ATMOSPHERE. FOR TUESDAY NIGHT AND WEDNESDAY...THE STORMY WEATHER PATTERN WILL CONTINUE ALTHOUGH THE MODELS ARE NOT IN SYNC WITH THE DETAILS. THE GFS PUSHES A COLD FRONT INTO THE REGION FROM THE NORTH QUICKER THAN THE ECMWF DOES. HOWEVER...THE MODELS DO AGREE THAT A VERY UNSTABLE AND MOIST ATMOSPHERE WILL BE LOCATED OVER THE MIDSOUTH INTO WEDNESDAY. KEPT THURSDAY RAINFREE AS DRIER AIR PUSHES INTO THE REGION FOLLOWING THE PASSAGE OF A WEAK COLD FRONT. FRIDAY LOOKS RAINFREE ALSO WITH A MILD START TO THE DAY BEFORE AFTERNOON TEMPERATURES WARM TO AROUND THE NORMAL VALUES FOR THIS TIME OF THE YEAR. LOOKING AT MODEL FORECAST CHARTS FOR FRIDAY NIGHT AND SATURDAY...YOU WOULD NOT THINK IT WAS JULY. THE MODELS ARE IN FAIRLY GOOD AGREEMENT FOR THAT FAR OUT. ANOTHER BROAD UNSEASONABLY DEEP UPPER LEVEL TROUGH WILL DIG ALONG THE EASTERN UNITED STATES. THE GFS INDICATES A 1010 MB LOW NEAR THE MO BOOTHEEL 7 AM SATURDAY WITH A COLD FRONT TRAILING TO THE SOUTHWEST WHILE THE ECMWF IS A LITTLE SLOWER AND STRONGER INDICATING A 1006 MB LOW OVER SOUTH CENTRAL MO WITH A TRAILING COLD FRONT TO THE SOUTHWEST. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL OCCUR AHEAD OF THIS SYSTEM FRIDAY NIGHT AND SATURDAY. COOLER AND DRY HIGH PRESSURE IS FORECAST TO BEHIND INTO THE REGION FROM THE NORTH WITH PASSAGE OF THE LOW PRESSURE SYSTEM AND COLD FRONT. JCL && .AVIATION... 12Z TAFS PRIMARY FORECAST CONCERN REMAINS TIMING AND LOCATION OF TSRA ONSET. TSRA CHANCES WILL INCREASE AT ALL LOCATIONS AFTER 15Z. PRESENCE OF ISOLATED SHRA/TSRA EARLY THIS MORNING INDICATES SOME ELEVATED INSTABILITY...BUT THIS ACTIVITY HAS FAILED TO ORGANIZE FOR ANY APPRECIABLE LENGTH OF TIME. FOR THE 12Z TAFS...HAVE NARROWED TEMPOS DOWN TO NEAR PEAK HEATING WITH RESPECT TO TSRA TIMING. OF CONCERN IS UPPER LEVEL LOW OVER NORTHEAST LA...WHICH COULD HELP INITIATE TSRA BY LATE MORNING. GFS LAMP GUIDANCE AND HRRR MODELS SHOWED LITTLE EFFECT OF THIS UPPER LEVEL FEATURE FOR THE MORNING HOURS. BUT WILL SKIES TO START THE DAY... AMPLE SURFACE HEATING OVER THE ARKLAMISS MAY TOUCH OFF MID/LATE MORNING TSRA POSSIBLY EXTENDING UP TOWARD MEM. PWB && && .PRELIMINARY POINT TEMPS/POPS... MEM 93 74 91 75 / 30 60 60 50 MKL 89 71 89 72 / 30 60 60 50 JBR 91 72 91 73 / 50 60 60 50 TUP 92 73 90 73 / 30 60 60 50 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
532 PM CDT SUN JUL 21 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND MONDAY ISSUED AT 330 PM CDT SUN JUL 21 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COUPLE SHORTWAVES UPSTREAM...ONE OVER WESTERN WISCONSIN WHICH IS RESPONSIBLE FOR THE CLUSTER OF SHOWERS AND STORMS MOVING OVER CENTRAL WISCONSIN...AND ANOTHER OVER IOWA. MAINLY THE SOUTHERN PORTION OF THE FORECAST AREA WILL BE IMPACTED WITH THESE STORMS FOR THE REST OF THE AFTERNOON...BUT NO SEVERE WEATHER IS EXPECTED. FURTHER UPSTREAM...THE NEXT SHORTWAVE IS PRODUCING STORMS OVER FAR SOUTH-CENTRAL CANADA AND NORTHERN NORTH DAKOTA WHICH WILL ARRIVE TOMORROW. PRECIP CHANCES FOR THE REST OF TODAY AND SEVERE WEATHER CHANCES TOMORROW ARE THE MAIN FORECAST CONCERNS. TONIGHT...SHORTWAVE IMPULSES MOVING EAST ACROSS THE REGION WILL TAKE UNTIL MID TO LATE EVENING TO EXIT. AS A RESULT...POTENTIAL WILL BE THERE FOR ISOLATED TO SCATTERED THUNDERSTORMS UNTIL THEN OVER THE SOUTHERN FORECAST AREA...EVEN THOUGH THE MAIN CLUSTER WILL HAVE PROBABLY EXITED BY THE START OF THE EVENING. PLENTY OF CLEARING OCCURRING UPSTREAM OF THE SHORTWAVES...THOUGH MODELS DEPICT WEAK ISENTROPIC ASCENT CONTINUING THROUGH THE NIGHT. AM THINKING WILL SEE A PERIOD OF SUBSIDENCE BEHIND THE WAVE...WHICH COULD LEAD TO A SEVERAL HOURS OF MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS. NOT SURE HOW LONG THIS WILL LAST...BUT 850MB THETAE ADVECTION DOES RAMP UP LATE AHEAD OF THE SHORTWAVE CURRENTLY MOVING INTO NORTHERN NORTH DAKOTA. NOT OUT OF THE QUESTION THAT CONVECTION COULD APPROACH N-C WISCONSIN LATE TONIGHT. SO WILL SHOW INCREASING CLOUDS AFTER MIDNIGHT ALONG WITH SLIGHT CHANCE TO CHANCE POPS OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. LOWS MAINLY IN THE MID 50S TO LOW 60S. MONDAY...THE NORTH DAKOTA SHORTWAVE WILL MOVE ACROSS NORTHERN WISCONSIN DURING THE MORNING. BOTH THE NAM AND GFS SHOW A DECENT WIND SHIFT OCCURRING AT 700MB SO WOULD NOT BE SURPRISED TO SEE SOME CONVECTION MOVE ACROSS THE NORTH. THEN A STRONG SHORTWAVE OVER WESTERN ONTARIO WILL DRIVE A COLD FRONT ACROSS NORTHWEST WISCONSIN DURING THE AFTERNOON. DEPENDING UPON IF PRECIP OCCURS OVER NORTHERN WISCONSIN AND HOW MUCH DESTABILIZATION CAN OCCUR WITH AMPLE CLOUD COVER...MODIFYING PROGGED SOUNDINGS NEAR RHINELANDER FOR AN 80F/64F PARCEL YIELDS 1700 J/KG OF ML CAPE AT 21Z. WITH 0-6KM BULK SHEAR VALUES OF 30-35KTS...POTENTIAL WILL BE THERE FOR SEVERE STORMS TOMORROW AFTERNOON OVER N-C AND POSSIBLY CENTRAL WISCONSIN TOO. WARM ADVECTION AHEAD OF THE FRONT WILL PUSH HIGHS TO THE UPPER 70S AND MID 80S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 330 PM CDT SUN JUL 21 2013 NOT MUCH CHANGE IN THE OVERALL FORECAST FOR THIS PERIOD AS SHORTWAVE TROFS MOVE THROUGH MEAN TROF POSITION ACROSS GREAT LAKES. LATEST GFS AND ECMWF IN GENERAL AGREEMENT THROUGH MOST OF PERIOD ON STRENGTH AND TIMING OF SYSTEMS. TEMPS WILL BE AOB NORMAL FOR MUCH OF WEEK...AFTER MONDAY. IN FACT...HIGHS NEXT WEEKEND MAY STRUGGLE TO REACH 70 ACROSS PARTS OF THE NORTH AS NW FLOW IS REINFORCED BEHIND LATE WEEK SYSTEM. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 516 PM CDT SUN JUL 21 2013 AREAS OF MVFR CIGS WILL SPREAD INTO CENTRAL AND NORTH CENTRAL WISCONSIN THROUGH THIS EVENING AND POSSIBLY OVER EAST CENTRAL WISCONSIN OVERNIGHT AS A SHORT WAVE TRACKS SOUTHEAST OF SOUTHEAST WISCONSIN. RETURN FLOW DEVELOPS OVERNIGHT WHICH COULD LEAD TO MORE MVFR CIGS OVER THE REGION. IF THESE MVFR CIGS BECOME MORE WIDESPREAD OVERNIGHT...MAY LINGER INTO MONDAY MORNING UNTIL MIXING LIFTS CIGS TO VFR LEVELS AHEAD OF AN APPROACHING COLD FRONT. SCATTERED MVFR CIGS AND VSBYS DUE TO SHOWERS AND STORMS LIKELY ALONG THIS FRONT STARTING MONDAY AFTERNOON OVER NORTHWEST WISCONSIN BEFORE REACHING SOUTHEAST WISCONSIN MONDAY NIGHT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......JKL AVIATION.......TDH
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND MONDAY ISSUED AT 330 PM CDT SUN JUL 21 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COUPLE SHORTWAVES UPSTREAM...ONE OVER WESTERN WISCONSIN WHICH IS RESPONSIBLE FOR THE CLUSTER OF SHOWERS AND STORMS MOVING OVER CENTRAL WISCONSIN...AND ANOTHER OVER IOWA. MAINLY THE SOUTHERN PORTION OF THE FORECAST AREA WILL BE IMPACTED WITH THESE STORMS FOR THE REST OF THE AFTERNOON...BUT NO SEVERE WEATHER IS EXPECTED. FURTHER UPSTREAM...THE NEXT SHORTWAVE IS PRODUCING STORMS OVER FAR SOUTH-CENTRAL CANADA AND NORTHERN NORTH DAKOTA WHICH WILL ARRIVE TOMORROW. PRECIP CHANCES FOR THE REST OF TODAY AND SEVERE WEATHER CHANCES TOMORROW ARE THE MAIN FORECAST CONCERNS. TONIGHT...SHORTWAVE IMPULSES MOVING EAST ACROSS THE REGION WILL TAKE UNTIL MID TO LATE EVENING TO EXIT. AS A RESULT...POTENTIAL WILL BE THERE FOR ISOLATED TO SCATTERED THUNDERSTORMS UNTIL THEN OVER THE SOUTHERN FORECAST AREA...EVEN THOUGH THE MAIN CLUSTER WILL HAVE PROBABLY EXITED BY THE START OF THE EVENING. PLENTY OF CLEARING OCCURRING UPSTREAM OF THE SHORTWAVES...THOUGH MODELS DEPICT WEAK ISENTROPIC ASCENT CONTINUING THROUGH THE NIGHT. AM THINKING WILL SEE A PERIOD OF SUBSIDENCE BEHIND THE WAVE...WHICH COULD LEAD TO A SEVERAL HOURS OF MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS. NOT SURE HOW LONG THIS WILL LAST...BUT 850MB THETAE ADVECTION DOES RAMP UP LATE AHEAD OF THE SHORTWAVE CURRENTLY MOVING INTO NORTHERN NORTH DAKOTA. NOT OUT OF THE QUESTION THAT CONVECTION COULD APPROACH N-C WISCONSIN LATE TONIGHT. SO WILL SHOW INCREASING CLOUDS AFTER MIDNIGHT ALONG WITH SLIGHT CHANCE TO CHANCE POPS OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. LOWS MAINLY IN THE MID 50S TO LOW 60S. MONDAY...THE NORTH DAKOTA SHORTWAVE WILL MOVE ACROSS NORTHERN WISCONSIN DURING THE MORNING. BOTH THE NAM AND GFS SHOW A DECENT WIND SHIFT OCCURRING AT 700MB SO WOULD NOT BE SURPRISED TO SEE SOME CONVECTION MOVE ACROSS THE NORTH. THEN A STRONG SHORTWAVE OVER WESTERN ONTARIO WILL DRIVE A COLD FRONT ACROSS NORTHWEST WISCONSIN DURING THE AFTERNOON. DEPENDING UPON IF PRECIP OCCURS OVER NORTHERN WISCONSIN AND HOW MUCH DESTABILIZATION CAN OCCUR WITH AMPLE CLOUD COVER...MODIFYING PROGGED SOUNDINGS NEAR RHINELANDER FOR AN 80F/64F PARCEL YIELDS 1700 J/KG OF ML CAPE AT 21Z. WITH 0-6KM BULK SHEAR VALUES OF 30-35KTS...POTENTIAL WILL BE THERE FOR SEVERE STORMS TOMORROW AFTERNOON OVER N-C AND POSSIBLY CENTRAL WISCONSIN TOO. WARM ADVECTION AHEAD OF THE FRONT WILL PUSH HIGHS TO THE UPPER 70S AND MID 80S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 330 PM CDT SUN JUL 21 2013 NOT MUCH CHANGE IN THE OVERALL FORECAST FOR THIS PERIOD AS SHORTWAVE TROFS MOVE THROUGH MEAN TROF POSITION ACROSS GREAT LAKES. LATEST GFS AND ECMWF IN GENERAL AGREEMENT THROUGH MOST OF PERIOD ON STRENGTH AND TIMING OF SYSTEMS. TEMPS WILL BE AOB NORMAL FOR MUCH OF WEEK...AFTER MONDAY. IN FACT...HIGHS NEXT WEEKEND MAY STRUGGLE TO REACH 70 ACROSS PARTS OF THE NORTH AS NW FLOW IS REINFORCED BEHIND LATE WEEK SYSTEM. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1223 PM CDT SUN JUL 21 2013 A SHOWER AND THUNDERSTORM COMPLEX WILL MARCH EAST ACROSS CENTRAL AND EAST-CENTRAL WISCONSIN THIS AFTERNOON. VSBYS AND CIGS TO FALL TO MVFR LEVELS WITHIN THE THUNDERSTORMS...BUT STRONG GUSTY WINDS OR LARGE HAIL WILL NOT OCCUR. BEHIND THE THUNDERSTORM COMPLEX...SATELLITE IMAGES SHOW MOSTLY CLEAR CONDITIONS UNTIL YOU REACH NORTH DAKOTA. AS A RESULT...THINK WILL SEE A PERIOD OF MOSTLY CLEAR TO SCT SKY CONDITIONS AFTER THE THUNDERSTORMS DEPART...UNTIL CLOUDS INCREASE LATE TONIGHT. THE DISTURBANCE JUST NORTH OF NORTH DAKOTA COULD BRING THUNDER TO NORTH-CENTRAL WISCONSIN TOMORROW MORNING...BUT CONFIDENCE IS NOT THERE TO INCLUDE IN THE TAFS AT THIS TIME. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......JKL AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
105 PM CDT SUN JUL 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 300 AM CDT SUN JUL 21 2013 CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS LOOKED VERY SIMILAR TO THIS TIME YESTERDAY...CONSISTING OF NORTHWEST FLOW FROM BRITISH COLUMBIA INTO THE GREAT LAKES REGION...NUMEROUS SHORTWAVES RIDING THROUGH THE FLOW...AND TROUGHING OVER SOUTHEAST CANADA. MOST OF THE SHORTWAVES ARE WEAK EXCEPT FOR A MORE IMPRESSIVE ONE OVER CENTRAL ALBERTA. THE MAIN SHORTWAVE OF INTEREST IN THE SHORT TERM IS ORIGINATING OUT OF CONVECTION OVER SOUTHEAST SD AND EASTERN NEBRASKA. AIRMASS OVER THE FORECAST AREA VARIES GREATLY FROM SOUTH TO NORTH WITH I-94 BEING A GREAT DIVIDING LINE. TO THE NORTH...DRIER AIR CHARACTERIZED BY SURFACE DEWPOINTS IN THE 40S AND LOW 50S WAS PRESENT. FARTHER UP TO THE NORTH...THE 00Z INL SOUNDING REPORTED A PRECIPITABLE WATER VALUE OF 0.49 INCHES. NOW...SOUTH AND WEST OF I-94...DEWPOINTS ARE IN THE 60S. THE 00Z SOUNDINGS FROM MPX AND DVN HAD PRECIPITABLE WATER VALUES AROUND 1.15 INCHES. SEPARATING THESE TWO AIRMASSES IS A STATIONARY FRONTAL BOUNDARY. ISOLATED SHOWERS/STORMS HAVE BEEN POPPING UP ALONG/NORTH OF THE BOUNDARY ALL NIGHT. SYNOPTIC OVERVIEW... NORTHWEST FLOW CONTINUES THROUGH THE SHORT TERM PERIOD. THE CONVECTIVELY INDUCED SHORTWAVE TROUGH APPROACHING SIOUX CITY IA AT 08Z MODELS ARE STRUGGLING WITH GREATLY. MOST MODELS...INCLUDING HI RESOLUTION RUNS SUCH AS THE HRRR AND HIRES-ARW ARE TOO SLOW. EXTRAPOLATION HAS THE MCV CROSSING MUCH OF IOWA THIS MORNING. POTENTIAL THEN EXISTS FOR SOME VERY WEAK RIDGING IN ITS WAKE FOR THIS AFTERNOON AND TONIGHT...AHEAD OF THE CURRENT ALBERTA SHORTWAVE WHICH DIGS INTO NORTHERN MN AND WESTERN ONTARIO BY 12Z MONDAY. TODAY... DESPITE THIS PERIOD BEING THE BEGINNING OF THE FORECAST...THE UNCERTAINTY IS QUITE HIGH. MUCH OF THIS UNCERTAINTY STEMS FROM THE TOO SLOW HANDLING FROM ALL MODELS REGARDING THE MCV APPROACHING SIOUX CITY IA AS OF 08Z. GENERALLY FOLLOWED AN EXTRAPOLATION APPROACH COMBINED WITH A SOMEWHAT SPED UP 21.05Z HRRR FORECAST TO COME UP WITH THE FORECAST TODAY. THE PLAN IS THAT THE MCV SHOULD TRACK ACROSS DES MOINES AND DAVENPORT THIS MORNING...WITH THE FORECAST AREA ON THE NORTH SIDE. SHOWERS AND A FEW EMBEDDED THUNDERSTORMS APPEAR LIKELY...PRIMARILY WEST OF THE MISSISSIPPI RIVER DURING THE MORNING HOURS. CONCERNED THAT THE DIURNAL EFFECTS ON LOW LEVEL MOISTURE TRANSPORT MAY CAUSE THE SHOWERS TO WEAKEN SOME AS WE APPROACH MID-DAY...THUS THE HIGHER CHANCES TO THE WEST. DURING THE AFTERNOON...IT IS HARD TO SAY WHATS GOING TO OCCUR. WE COULD EASILY BE IN SUBSIDENCE IN THE WAKE OF THE MCV...PREVENTING MUCH IN THE WAY OF ADDITIONAL PRECIPITATION. ON THE OTHER HAND...THE AFTERNOON IS PEAK HEATING AND WITH HIGHER DEWPOINTS TODAY...WE SHOULD BE ABLE TO BUILD 500-1500 J/KG OF CAPE AS SUGGESTED BY THE RAP. ANY SHORTWAVE COMING THROUGH THE NORTHWEST FLOW THATS HARD TO DISCERN AT THIS TIME COULD KICK OFF SHOWERS AND STORMS. ADDITIONALLY WE SHOULD STILL HAVE THAT STATIONARY FRONTAL BOUNDARY IN THE FORECAST AREA TO PROVIDE WEAK LOW LEVEL CONVERGENCE. THEREFORE... HAVE MAINTAINED AT LEAST 40-50 PERCENT CHANCES FOR THE AFTERNOON. REGARDING TEMPERATURES...ASSUMING SOME SUN TODAY WHICH SHOULD OCCUR...925MB TEMPS IN THE 18-20C RANGE SUPPORTS HIGHS IN THE 70S TO NEAR 80. TONIGHT... ANY CONVECTION THAT OCCURS THIS AFTERNOON WILL LIKELY HAVE A STRONG DIURNAL COMPONENT TO IT. THEREFORE...HAVE PRECIPITATION CHANCES DIMINISHING THROUGH THE EVENING HOURS. HOWEVER...850MB MOISTURE TRANSPORT DOES INCREASE THROUGH THE NIGHT AHEAD OF THE STRONGER SHORTWAVE DROPPING INTO NORTHERN MN. CONVECTION WILL LIKELY FORM ON THE NOSE OF THIS MOISTURE TRANSPORT...WHICH IS FORECAST FROM NORTHERN MN INTO NORTHERN WI. KEPT SOME 20 PERCENT CHANCES OVERNIGHT BOTH OVER TAYLOR/CLARK COUNTIES FOR THE NOSE OF THIS MOISTURE TRANSPORT. ALSO KEPT THE 20 PERCENT CHANCES OVERNIGHT FOR THE EASTERN HALF OF THE FORECAST AREA...IN THE EVENT ANY DIURNAL CONVECTION CAN SURVIVE...THOUGH AS THE CHANCE STATES THE CONFIDENCE IS LOW. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 300 AM CDT SUN JUL 21 2013 SYNOPTIC OVERVIEW... 20.00Z ECMWF/GFS/CANADIAN ALL CONTINUE THE NORTHWEST FLOW PATTERN THROUGH THE ENTIRE LONG TERM PERIOD. WHAT LOOKED TO BE A POSSIBILITY OF RIDGING BUILDING TOWARDS THE AREA BRIEFLY THURSDAY INTO FRIDAY IS NOW COMPLETELY GONE. PART OF THE REASON WE STAY IN NORTHWEST FLOW IS THE DEVELOPMENT OF AN OMEGA BLOCK OVER WESTERN CANADA BETWEEN TUESDAY AND WEDNESDAY...WHICH DOES NOT SHOW ANY SIGNS OF BREAKING DOWN FOR AWHILE. ADDITIONALLY...THERE APPEARS TO BE SOME MODEL STRUGGLES HANDLING SHORTWAVE TROUGHING COMING DOWN THE EAST SIDE OF THE OMEGA BLOCK...WHICH PUTS MORE UNCERTAINTY FOR THE FORECAST THURSDAY AND BEYOND. ONE THING THAT IS STARTING TO BECOME A LITTLE MORE EVIDENT IS FOR DEEPER TROUGHING OVER THE GREAT LAKES REGION AT THE END OF NEXT WEEKEND. 500MB STANDARDIZED ANOMALIES FOR 12Z SUNDAY FROM THE ECMWF/GFS ARE 1.5-2 BELOW NORMAL. HAZARDS... THERE COULD BE SOME ISOLATED SEVERE WEATHER LATE MONDAY AFTERNOON INTO THE EVENING HOURS...ASSOCIATED WITH A COLD FRONT COMING THROUGH...BUT CONFIDENCE IS LOW AS DESCRIBED BELOW. MONDAY THROUGH TUESDAY NIGHT... MUCH OF THE FOCUS HERE IS ON THE MONDAY/MONDAY NIGHT PERIOD. SHORTWAVE TROUGH OVER NORTHERN MN AND WESTERN ONTARIO AT 12Z MONDAY MODELS ALL AGREE ON SLIDING IT ACROSS NORTHERN ONTARIO. AS THIS OCCURS...A COLD FRONT ASSOCIATED WITH IT APPROACHES THE FORECAST AREA. TIMING ON THIS FRONT VARIES GREATLY. AT 00Z TUESDAY...TIMING VARIES FROM THE 21.00Z HIRES-ARW HAVING IT WEST OF MINNEAPOLIS TO THE 21.00Z ECMWF/GFS OVER MINNEAPOLIS AND THE 21.00Z CANADIAN/NAM/UKMET WHICH ARE OVER LA CROSSE. TRENDS AT LEAST FROM THE ECMWF/GFS SUGGEST A SLOWER APPROACH MAY BE THE WAY TO GO. THERE STILL REMAINS UNCERTAINTY ON CONVECTIVE CHANCES WITH THIS FRONT... 1. A WARM SURGE OF AIR AT 800MB IS STILL INDICATED TO COME OVER THE FRONT TO PROVIDING POTENTIAL CAPPING 2. THE SHORTWAVE TROUGH SLIDING ACROSS NORTHERN ONTARIO COULD END UP PUTTING RIDGING OVER THE FRONT FOR THE AFTERNOON AS SUGGESTED BY THE 21.00Z HIRES-ARW. 3. LOW LEVEL CONVERGENCE ON THE FRONT REMAINS IN QUESTION. 4. NOW THE FRONT BEING SLOWER...NOT COMING ACROSS THE FORECAST AREA AT PEAK HEATING...COULD BE A NEGATIVE FOR PRECIP. TO ACCOUNT FOR THE SLOWER TREND HAVE LOWERED PRECIPITATION CHANCES SOME MONDAY AFTERNOON. LEFT THE 40-60 PERCENT CHANCES FOR MONDAY EVENING AS THAT IS STILL FAIRLY WELL AGREED UPON BY GUIDANCE...THEN CHANCES DIMINISHING AFTER MIDNIGHT WITH LOSS OF HEATING AND THE FRONT PROGRESSING THROUGH THE AREA. DRY WEATHER FOLLOWS IN THE WAKE OF THE FRONT FOR TUESDAY AND TUESDAY NIGHT WHILE HIGH PRESSURE BUILDS IN AT THE SURFACE. 925MB TEMPS CLIMBING TO 21-24C AHEAD OF THE FRONT ON MONDAY PLUS SUNSHINE WILL ALLOW HIGHS TO CLIMB INTO THE 80S. MAY EVEN SEE 90 IN A FEW SPOTS IF MORE SUN OCCURS. MONDAY LOOKS HUMID AS WELL AS NEAR 70 DEGREE DEWPOINTS ADVECT IN AT THE SURFACE. COOLER HIGHS ON THE WAY FOR TUESDAY AS 925MB TEMPS TUMBLE TO 17-20C. TUESDAY NIGHT LOWS HAVE POTENTIAL TO GET INTO THE 40S AT THE TYPICAL COLDER SPOTS...DUE TO LIGHT WINDS AND PRECIPITABLE WATER VALUES FALLING TO 0.5-0.75 INCHES. WEDNESDAY THROUGH SATURDAY NIGHT... 20.00Z ECMWF/GFS/CANADIAN ARE SUGGESTING NUMEROUS WEAK SHORTWAVES DROP SOUTHEAST ACROSS THE FORECAST AREA WEDNESDAY THROUGH THURSDAY IN THE NORTHWEST FLOW ALOFT. HARD TO SAY IF ANY OF THESE ARE GOING TO DO ANYTHING PRECIP WISE. 20.00Z CANADIAN AND 19.12Z ECMWF WANT TO BRING SOME SHOWERS ACROSS WEDNESDAY NIGHT AND THURSDAY...THOUGH THE 20.00Z ECMWF BACKED OFF. WOULD THINK A DRIER SCENARIO IS MORE LIKELY GIVEN THE DRY AIRMASS COMING IN TUESDAY NIGHT/WEDNESDAY WITH CANADIAN HIGH PRESSURE IN PLACE. NEVERTHELESS...DID HONOR A 20 PERCENT CHANCE MAINLY ON THURSDAY JUST IN CASE. CHANCES INCREASE A LITTLE FOR THURSDAY NIGHT AND FRIDAY WHERE IT APPEARS A COLD FRONT WILL CROSS THE AREA...ASSOCIATED WITH A POTENT UPPER TROUGH DROPPING OVER MANITOBA AND NORTHERN ONTARIO. SOME OF THIS UPPER TROUGH LOOKS TO SWING ACROSS THE FORECAST AREA FRIDAY NIGHT AND SATURDAY...THUS STILL NEED TO CONTINUE AT LEAST 20 PERCENT CHANCES. BEING IN THIS NORTHWEST FLOW PATTERN COMBINED WITH EVEN DEEPER TROUGHING FORMING OVER THE WEEKEND SUGGESTS BELOW NORMAL TEMPERATURES. BY 12Z SUNDAY...BOTH THE 20.00Z ECMWF AND GFS DEPICT 850MB TEMPS FALLING TO 6-9C...CHILLY RELATIVELY SPEAKING FOR THE END OF JULY. && .AVIATION...THROUGH 18Z MONDAY 105 PM CDT SUN JUL 21 2013 MESOSCALE VORTICITY MAX SPINNING INTO NORTHEAST IA EARLY THIS AFTERNOON AND HELPING TO ENHANCE SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL AREA. LOOKS LIKE THUNDER WILL REMAIN NORTH OF BOTH TAF LOCATIONS FOR THE MOST PART. CANNOT COMPLETELY RULE OUT A RUMBLE OF THUNDER...BUT CHANCE IS SO SMALL THAT IT WAS NOT INCLUDED IN THE TAFS. ONCE THE MCV MOVES PAST...ANTICIPATE THAT THE SHOWER ACTIVITY WILL DISSIPATE. SOME MODELS DO INDICATE THAT ADDITIONAL DEVELOPMENT WILL OCCUR...BUT DO NOT FEEL THIS WILL IMPACT EITHER TAF LOCATION. WITH RAIN TODAY...AND GENERALLY WEAK FLOW OVERNIGHT...ANTICIPATE SOME LIGHT FOG/MIST TO FORM. MAINTAINED MENTION IN THE FORECASTS. NEXT DISTURBANCE AND ASSOCIATED COLD FRONT WILL MOVE THROUGH DURING THE AFTERNOON HOURS ON MONDAY. LATER TAF ISSUANCES WILL HAVE TO ACCOUNT FOR CONVECTIVE POTENTIAL NEAR AND AHEAD OF THE FRONT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...MW