Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/07/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
851 PM MDT FRI SEP 6 2013 .UPDATE... && .SHORT TERM...SCATTERED SHOWERS AND ISOLATED TS STORMS STILL ON GOING OVER THE MOUNTAINS AND HIGH VALLEYS WITH SOUTHERLY STEERING FLOW MOVING STORMS FROM SOUTH TO NORTH. THE WEAK ACTIVITY OVER THE NORTHEAST PLAINS HAS DISSIPATED WHILE OUTFLOW BOUNDARY CONTINUES TO PUSH SOUTHEAST INTO THE PALMER DIVIDE AND WASHINGTON COUNTY. DON`T EXPECT ANY MORE SHOWERS OVER THE PLAINS WITH LACK OF ANY ADDITIONAL BOUNDARY COLLISIONS. THE STORMS IN THE MOUNTAINS WILL GRADUALLY DIMINISH AROUND MIDNIGHT WITH GRADUAL CLEARING SKIES. .AVIATION...SURFACE WINDS HAVE SHIFTED TO NORTH TO NORTHEAST THIS EVENING FOLLOWING EARLIER OUTFLOW BOUNDARY. EXPECT A CONTINUED WEAKENING OF THE NORTHERLY WINDS AND THEN A SHIFT BACK TO DRAINAGE WINDS TOWARDS MIDNIGHT. GRADUAL CLEARING OF THE MID LEVEL DECK THROUGH THE NIGHT. && .PREV DISCUSSION... /ISSUED 357 PM MDT FRI SEP 6 2013/ SHORT TERM...PRESENT FORECAST GRIDS NEED LITTLE WORK. ONGOING CONVECTION SHOULD CONFINE ITSELF MOSTLY TO THE FOOTHILLS THIS EVENING ALTHOUGH SEVERAL RECENT HRRR RUNS WANT TO BRING A BIT OF IT SOUTHEAST ACROSS THE NORTHERN/CENTRAL PORTIONS OF THE URBAN CORRIDOR TOWARDS 00Z. SATURDAY SHOULD BE CLOSE TO A CARBON COPY OF TODAY AS THE UPPER LEVEL ANTICYCLONE KEEPS ITS FURNACE-LIKE GRIP ON THE REGION. WELL ABOVE NORMAL TEMPERATURES EXPECTED AGAIN TOMORROW AFTERNOON WITH SOME CONVECTION AGAIN BREAKING OUT OVER THE HIGHER TERRAIN. CONVECTIVE PROBABILITIES SATURDAY WILL DECREASE QUICKLY AS ONE MOVES AWAY FROM THE MOUNTAINS...SIMILAR TO TODAY. LONG TERM...SOME CHANGES AS WE GET INTO NEXT WEEK. UPPER RIDGE WILL SHIFT EAST ALLOWING FOR MOISTURE TO INCREASE AGAIN BY MONDAY. MEANWHILE A SHORT WAVE TROUGH MOVING ACROSS THE NORTHERN U.S. BORDER WILL PUSH SOME LESS HOT LOW LEVEL AIR SOUTHWARD ON MONDAY. THE MAIN IMPACTS LOOK LIKE THE LOW LEVEL COOLING...AND HIGH LEVEL MOISTENING. THIS COULD WIND UP BEING SIMILAR TO THE COOLER PERIODS WE HAD 5 TO 10 DAYS AGO WHEN IT WAS WARM AND MOIST...BUT NOT WARM ENOUGH TO SUPPORT LOTS OF CONVECTION DUE TO THE CLOUD COVER AND NOT MUCH COOLING ALOFT. MODELS WANT TO PRODUCE INCREASED PRECIPITATION IN THE MONDAY THROUGH THURSDAY TIME PERIOD...BUT I AM HESITANT TO RAISE POPS TOO MUCH DUE TO THE STABILITY ISSUE. THERE WILL PROBABLY BE MORE CONVECTIVE ACTIVITY...BUT OVERALL IT WILL LIKELY BE WEAK. POSSIBLE EXCEPTION WILL BE MONDAY WHEN THERE COULD BE BOTH LOW LEVEL CONVERGENCE AND A LITTLE UPPER LEVEL DIVERGENCE THAT COULD SUSTAIN SOMETHING MORE ORGANIZED. TEMPERATURES WILL BE AFFECTED AS MUCH BY THE CLOUD COVER AS THE ACTUAL COOLING...MINIMUM TEMPERATURES MAY STILL BE PRETTY MILD. SLIGHT WARMING AND DRYING DURING THE LATER PART OF THE WEEK BUT WE WILL STILL BE UNDER SW FLOW ALOFT AND PROBABLY STILL A LOT OF HIGH CLOUDINESS. RIDGE REBUILDS BY NEXT WEEKEND...HARD TO TELL HOW MUCH CLOUD COVER THERE WILL BE...IF IT DRIES OUT A BIT WE WILL LIKELY BE NEAR RECORD HIGHS AGAIN...THOUGH PROBABLY NOT AS HOT AS WE ARE NOW. AVIATION...THUNDERSTORM THREAT LOOKS PRETTY SMALL AT THE TERMINALS THIS EVENING AND AGAIN ON SATURDAY. WINDS ARE BEHAVING ABOUT AS EXPECTED AT THIS POINT. SOME OF THE SMALLER SCALE MODELS ARE SUGGESTING A MODERATELY STRONG OUTFLOW BOUNDARY WILL MOVE ACROSS THE TERMINALS TOWARDS 00Z. PRESENT TAFS HAVE THIS SUGGESTED WITH THE WESTERLY WINDS AT 00Z. NORMAL DIURNAL PATTERNS LATER TONIGHT. HYDROLOGY...CONVECTIVE ACTIVITY IS MOVING NORTHWARD AT A DECENT CLIP THIS AFTERNOON. STRONG STORMS MOVED ACROSS THE HIGH PARK BURN AREA EARLY THIS AFTERNOON AND ADDITIONAL STORMS MAY CROSS THAT AREA AS WELL AS FOUR MILE LATER TODAY. THESE STORMS WILL POSE SOME FLOODING THREAT. A SIMILAR SITUATION WILL EXIST SATURDAY AFTERNOON. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ENTREKIN LONG TERM....GIMMESTAD AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS TAUNTON MA
649 AM EDT THU SEP 5 2013 .SYNOPSIS... A SHARP COLD FRONT WILL SWEEP ACROSS THE REGION THIS MORNING WITH A FEW BRIEF SHOWERS. DRY WEATHER FOLLOWS WITH UNSEASONABLY COOL CONDITIONS LATE TODAY INTO FRIDAY. TEMPERATURES MODERATE TO SEASONAL LEVELS THIS WEEKEND...BEFORE ANOTHER COLD FRONT BRINGS SOMEWHAT COOLER AIR EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 645 AM UPDATE... LOWERED RAINFALL CHANCES THIS MORNING BASED ON LATEST RADAR DATA...WHICH IS SHOWING RAINFALL DRYING SLIGHTLY AS IT MOVES EAST. MOST OF THE RAPID REFRESH MODELS..SUCH AS THE HRRR AND RAP...ARE CONSISTENTLY SHOWING A SLIGHT INCREASE IN COVERAGE FROM PRESENT LATER THIS MORNING AS THE COLD FRONT MOVES INTO CENTRAL AND EASTERN MA. THIS MAKES SENSE AS WE WILL BE AFTER SUNRISE...AND THE LOW LEVEL LAPSE RATES SHOULD BE AT LEAST A LITTLE MORE FAVORABLE. OTHERWISE...THE TIMING OF THE PREVIOUS FORECAST LOOKS GOOD WITH A COLD FRONT MOVING OFFSHORE AROUND NOON. MADE MINOR TWEAKS TO TEMPERATURES AS WELL TO BRING THEM IN LINE WITH OBSERVED TRENDS. PREVIOUS DISCUSSION... SFC OBS AND MSAS SUGGEST STRONG SFC COLD FRONT IS JUST ON THE NW DOORSTEP OF BOX CWA THIS HOUR...HAVING ALREADY MOVED THROUGH CENTRAL VT/NH. PRECIP HAS BEEN VERY CLOSELY ASSOCIATED WITH THIS FRONT GIVEN LACK OF DEEP MOISTURE FLUX /MOISTURE IS LIMITED TO THE H85-H5 LAYER/ AND REQUIRES ALL FRONTOGENETICAL FORCING. AM NOTING A FAIR AMOUNT OF DRYING OF THESE -SHRA AS THEY APPROACH THE VERY DRY AIRMASS ALREADY IN PLACE OVER SRN NEW ENGLAND. THEREFORE...DESPITE THE MOISTURE AND LATEST MODEL TREND TO LEAN TOWARD LIKELY- CATEGORICAL POPS WILL CONTINUE TO CAP POPS AT CHANCE AS THE FRONT SLIDES THOUGH THIS MORNING. TIMING THIS FRONT TO REACH SRN NH AND THE MASS BORDER BY 09-10Z...CENTRAL MA BY 13-14Z AND TO THE S COAST BY ABOUT 16-18Z. TIMING OF HIGHEST POPS FOLLOW THE TIMING OF THE FRONT. IT IS POSSIBLE HOWEVER...GIVEN THE LACK OF MOISTURE AND RECENT RADAR TRENDS...THAT MANY LOCATIONS MAY REMAIN DRY WITH THIS FROPA. AREAS THAT DO SEE RAINFALL WILL LIKELY ONLY SEE ENOUGH TO WET THE GROUND. STRONG COLD ADVECTION AND SOME CLOUD COVER WITH THIS FRONT SUGGEST A NON-DIURNAL TEMP TREND WITH THE HIGHS LIKELY ARRIVING ABOUT MID DAY TO EARLY AFTERNOON WITH GRADUAL DECREASES INTO THE EVENING HOURS. LATEST MAV/MET GUIDANCE SHOWS THIS WELL. CLOUDS ARE LIKELY TO RAPIDLY DISSIPATE TO NEAR SKC CONDITIONS BY THIS EVENING AS DRY AIR WORKS IN WITH HIGH PRES AND THE ACCOMPANYING CAA. WINDS WILL ALSO BE BRIEFLY GUSTY...REACHING 20+ MPH AT TIMES JUST BEHIND THE FRONT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... TONIGHT... STRONG COLD ADVECTION CONTINUES INITIALLY ALLOWING H85 TEMPS TO DIP AS LOW AS +2C BY THE EVENING HOURS. THE PRIMARY EFFECT FROM THIS WILL BE THE POSSIBILITY OF SOME OCEAN EFFECT CLOUDS AND POSSIBLY EVEN LIGHT SHOWERS WHICH MAY EFFECT THE CAPE/ISLANDS OVERNIGHT WITH N FLOW. GIVEN THE DIFFERENCE WITH SST/S AROUND +18 TO +20C THERE SHOULD BE ENOUGH NEAR SFC INSTABILITY TO GENERATE THESE OCEAN EFFECT CLOUDS. WILL KEEP POPS OUT FOR THE TIME BEING AS WELL MIXED AND DRY BL MAY KEEP ANY -SHRA FROM REACHING THE SFC. OTHERWISE...SKC CONDITIONS IN THE INTERIOR AND SLACKENING MASS FIELDS SUGGEST GOOD RADIATIONAL COOLING WHICH COULD LEAD SOME VALLEYS IN THE NW PORTIONS OF THE CWA TO DIP BELOW THE 36F THRESHOLD DURING THE EARLY MORNING HOURS. THEREFORE...WILL BE ISSUING A STATEMENT FOR THE THREAT OF SOME PATCHY FROST IN TYPICALLY COLDER VALLEYS. WILL LIMIT THE STATEMENT TO CHESHIRE COUNTY IN NH...AS WELL AS FRANKLIN AND NORTHERN WORCESTER COUNTIES IN MA. DAY CREW MAY NEED TO CONSIDER A FULL FLEDGED FROST ADVISORY IF MODEL COOLING TREND CONTINUES. ELSEWHERE...EVEN THOUGH PLACES WILL BE TOO COOL FOR FROST WILL STILL BE MUCH COOLER THAN PREVIOUS NIGHTS...WITH TEMPS RANGING FROM THE MID 30S TO MID 40S. FRI... COOL START TO THE DAY WILL WITH FULL SUNSHINE WILL REALIZING THE INCREASING H85 TEMPS THROUGH THE DAY. THESE TEMPS SHOULD TOP OUT AT ABOUT +6C BY LATE AFTERNOON. THEREFORE...MAX TEMPS GENERALLY REMAIN AT OR BELOW THE 70F MARK FOR THE DAY. HIGH PRES REMAINS IN CONTROL WITH DRY WX. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * MAINLY DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK * TEMPERATURES MODERATE TO NEAR NORMAL THIS WEEKEND DETAILS... FRIDAY NIGHT AND SATURDAY... EXPECTING GOOD RADIATIONAL COOLING CONDITIONS FRIDAY NIGHT...BUT LOW TEMPERATURES WILL NOT BE QUITE AS CHILLY AS THURSDAY NIGHT. AFTER A COOL START EARLY SATURDAY...A HIGH PRESSURE MOVING OFF THE COAST WILL ALLOW FOR A RETURN SOUTHWEST FLOW OF AIR INTO SOUTHERN NEW ENGLAND. PLENTY OF SUNSHINE EARLY IN THE DAY...BUT WE SHOULD SEE AN INCREASE IN MID AND HIGH CLOUDS DURING THE AFTERNOON IN THE WARM AIR ADVECTION PATTERN. SATURDAY NIGHT AND SUNDAY... A COLD FRONT WILL MOVE ACROSS THE REGION SOMETIME SUNDAY. THERE IS LITTLE MOISTURE OR INSTABILITY AHEAD OF THIS FRONT...BUT CANNOT RULE OUT A BRIEF SPRINKLE/SPOT SHOWER OR TWO SOMETIME DURING THIS TIME FRAME. EVEN IF THIS HAPPENS THOUGH...THE VAST MAJORITY OF THE TIME WILL BE DRY SO HAVE MAINTAINED LOW POPS. MONDAY THROUGH WEDNESDAY... DRY BUT SOMEWHAT COOLER WEATHER EXPECTED MONDAY BEHIND A COLD FRONT. HOWEVER...AIRMASS DOES NOT LOOK AS CHILLY AS WHAT WE WILL HAVE THIS LATE THIS WEEK...WITH THE CORE OF COLDER AIR OVER NORTHERN NEW ENGLAND. A HIGH PRESSURE SHOULD MOVE OFF THE COAST ALLOWING FOR A RETURN OF WARMER AIR FOR TUESDAY AND ESPECIALLY WEDNESDAY. DRY WEATHER SHOULD PREVAIL MOST OF THE TIME THROUGH WEDNESDAY. A WARM FRONT PASSING NEARBY MAY BE ENOUGH TO TRIGGER ISOLATED SHOWERS IF ENOUGH MOISTURE CAN BE POOLED TOGETHER TUESDAY INTO WEDNESDAY. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW /THROUGH FRIDAY/...HIGH CONFIDENCE OVERALL... MAINLY VFR THROUGH THE PERIOD. HOWEVER A PERIOD OF -SHRA WILL MOVE ACROSS THE REGION FROM N TO S FROM ABOUT 08Z-18Z...EXITING OFFSHORE AFTER 18Z...AND THERE MAY BE LOCALIZED MVFR CONDITIONS WITHIN THESE -SHRA. OTHERWISE...SOME MVFR CIGS ARE POSSIBLE OVER THE CAPE/ISLANDS LATE THIS EVENING AS SOME OCEAN EFFECT CLOUDS DEVELOP. WIND GUSTS 15-20 KT POSSIBLE AT TIMES ONCE WINDS SHIFT TO THE NNW THIS MORNING BEHIND THE COLD FRONT. KBOS TERMINAL...GENERALLY HIGH CONFIDENCE IN TAF...ALTHOUGH A BRIEF PERIOD OF MVFR IS POSSIBLE IN SOME -SHRA THIS MORNING. ALSO...WINDS MAY SHIFT MORE NNE BEHIND THE COLD FRONT MID MORNING INTO THE AFTERNOON. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... HIGH CONFIDENCE IN MAINLY VFR CONDITIONS THROUGH THE PERIOD. MAY SEE SOME VERY LOCALIZED PATCHY GROUND FOG IN THE TYPICALLY PRONE LOCATIONS DURING THE LATE NIGHT/EARLY MORNING HOURS. THERE ALSO IS LOW PROBABILITY OF BRIEF MVFR CONDITIONS SAT NIGHT AND EARLY SUNDAY IN SHOWERS AHEAD OF A COLD FRONT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY NIGHT/...HIGH CONFIDENCE. MAIN ISSUE TODAY WILL BE THE THREAT FOR OCCASIONAL SMALL CRAFT ADVISORY LEVEL WINDS ESPECIALLY AROUND THE MID DAY PERIOD. WIND GUSTS MAY APPROACH 25 KT AT TIMES...BUT THE TIMING WILL BE SHORT LIVED AND MANY GUSTS WILL STAY BELOW THIS THRESHOLD. THEREFORE...WILL HOLD OFF ON ANY HEADLINES BUT MENTION THE THREAT FOR A FEW GUSTS TO 25 KT IN THE COASTAL FORECAST. OTHERWISE...HIGH PRES BUILDS OVER THE WATERS LATE TONIGHT INTO TOMORROW WITH GENERAL DRY AND QUIET BOATING WEATHER EXPECTED. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT...HIGH CONFIDENCE. HIGH PRESSURE OVERHEAD WILL KEEP WINDS/SEAS WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS. SATURDAY...MODERATE CONFIDENCE. HIGH PRESSURE MOVING EAST OF THE WATERS WILL ALLOW FOR SOUTHWEST WINDS TO DEVELOP. CONDITIONS SHOULD GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS...BUT A PERIOD OF SOUTHWEST WIND GUSTS OF 20 TO 25 KNOTS ARE POSSIBLE ACROSS THE NEAR SHORE WATERS OF THE SOUTH COAST DURING THE AFTERNOON. THIS MAY RESULT IN SOME CHOPPY SEAS ACROSS THE SOUNDS AND BAYS. SUNDAY AND MONDAY...MODERATE CONFIDENCE. A PERIOD OF NORTHERLY SMALL CRAFT ADVISORY WIND GUSTS AND SEAS ARE POSSIBLE LATE SUNDAY INTO EARLY MONDAY BEHIND A COLD FRONT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...BELK/DOODY NEAR TERM...BELK/DOODY SHORT TERM...DOODY LONG TERM...BELK AVIATION...BELK/DOODY MARINE...BELK/DOODY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
930 PM EDT FRI SEP 6 2013 .UPDATE... CURRENTLY/OVERNIGHT...REMNANT STRATIFORM RAIN FROM AFTERNOON/EVENING MCS HAS JUST ABOUT DISSIPATED. CONSIDERABLE DEBRIS CLOUDINESS WILL COVER THE AREA PAST MIDNIGHT. HIGH PRESSURE TO THE NORTH IS FORECAST TO BRIDGE ACROSS THIS WEAK FRONT AND PRODUCE LIGHT NORTHEAST WINDS OVERNIGHT. THE LATEST HRRR MODEL DOES NOT SHOW ANY ADDITIONAL PRECIP OVERNIGHT BUT OUR LOCAL WRF SHOWS SOME SHOWERS DEVELOPING ALONG THE TREASURE COAST. THIS IS ENTIRELY UNDERSTANDABLE AS MOISTURE DEPTH IS FORECAST TO BE THE GREATEST THERE AND LOW LEVEL FLOW SHOULD BE WEAKLY CONFLUENT DUE TO THE WEAKENING FRONTAL TROUGH. SO NOT PLANNING TO CHANGE THE CURRENT FORECAST MUCH. && .AVIATION...MAIN ISSUE IS LOW STRATUS THAT RECENTLY DEVELOPED. WOULD THINK THAT IT WILL NOT BE AN ALL NIGHT THING AS LOW LEVEL FLOW IS FORECAST TO SWING AROUND TO THE NORTHEAST. HOWEVER WITH WEAKLY LOW LEVEL CYCLONIC FLOW I HAVE SEEN LOW CLOUDS HANG AROUND LONGER THAN EXPECTED...BUT THAT IS TYPICALLY IN THE COOL SEASON...SO HAVE NOT CARRIED THE STRATUS FOR VERY LONG INTO THE NIGHT. DID NOT LOOK REAL CLOSE AT THE SAT FORECAST BUT THE MODELS HAVE BEEN BRINGING DRYING ALOFT INTO THE AREA FROM THE NORTH SO THE CHANCES FOR AFTERNOON STORMS LOOK MUCH LOWER...20 PERCENT OR LESS. && .MARINE... TONIGHT-SAT...A WEAK NORTHEAST FLOW IS FORECAST TO SET IN OVERNIGHT THEN PICK UP TO AROUND 10 KNOTS ON SAT. A SMALL EAST SWELL SHOULD KEEP SEA HEIGHTS ELEVATED TO 3-4 FEET OFFSHORE. A SMALL CHANCE FOR SHOWERS OR STORMS SHOULD BE CONFINED TO SOUTH OF CANAVERAL AND MAYBE EVEN SOUTH OF SEBASTIAN INLET. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ FORECASTS...LASCODY IMPACT WX/RADAR...WIMMER
AREA FORECAST DISCUSSION
NWS MIAMI FL
847 PM EDT FRI SEP 6 2013 .UPDATE... ALTHOUGH IT WAS A LATE START FOR THE AFTERNOON SHOWERS AND STORMS...A LARGE AREA OF HEAVY SHOWERS AND STORMS HAS DEVELOPED AND BECOME FOCUSED OVER THE GULF COAST AREAS FROM NAPLES TO EVERGLADE CITY TO CENTRAL COLLIER COUNTY THIS EVENING. THE LATEST RADAR SCAN ESTIMATED TOTALS RANGING FROM HALF OF AN INCH OVER THE BULK OF THIS AREA WITH ISOLATED AMOUNTS AS HIGH AS 2.5". THE LATEST HRRR MODEL REFLECTIVITIES LINE UP WELL WITH THIS ACTIVITY AND GENERALLY CONTINUES TO SUPPORT THIS COVERAGE WELL INTO THE LATE EVENING HOURS BEFORE DISSIPATING. IF THIS VERIFIES...AN ADDITIONAL HALF OF AN INCH TO ONE INCH WITH LOCALLY HIGHER AMOUNTS WILL BE EXPECTED. THE LATEST FORECAST PACKAGE HAS BEEN UPDATED TO REFLECT THESE LATEST TRENDS. OTHERWISE...THE PREVIOUS FORECAST REMAINS ON TRACK THIS EVENING. && .PREV DISCUSSION... /ISSUED 736 PM EDT FRI SEP 6 2013/ AVIATION... VFR PREVAILING AT ALL TERMINALS. VCTS ONLY FOR KAPF THIS EVENING DUE TO THE ACTIVITY ALREADY NEARBY. EXPECT THIS TO DISSIPATE BY 04Z. VCSH WILL POSSIBLY DEVELOP NEAR ALL EASTERN TERMINALS BY 07/16Z AND WEST COAST SEA BREEZE DEVELOPING BY 07/18Z. VCTS WILL BE POSSIBLE NEAR KAPF BY THAT TIME ALSO. PREV DISCUSSION... /ISSUED 230 PM EDT FRI SEP 6 2013/ .TYPICAL SUMMER TIME WEATHER THIS WEEKEND BEFORE DRIER CONDITIONS EARLY NEXT WEEK... SHORT TERM... THE EAST AND WEST COAST SEA BREEZES HAVE DEVELOPED EARLY THIS AFTERNOON WITH THE EAST COAST SEA BREEZE PUSHING ACROSS THE INTERIOR AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH WEST ACROSS SOUTH FLORIDA THROUGH THE AFTERNOON HOURS...AS THE WEST COAST SEA BREEZE REMAINS OVER THE WEST COAST METRO AREAS. AT THE SAME TIME...A TROUGH OF LOW PRESSURE OVER NORTH FLORIDA WILL CONTINUE TO MOVE SOUTH INTO CENTRAL FLORIDA. THIS WEATHER PATTERN WILL ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE INTERIOR AND WEST COAST METRO AREAS THIS AFTERNOON INTO EARLY THIS EVENING...WITH ISOLATED SHOWERS ONLY FOR THE EAST COAST METRO AREAS. SO WILL KEEP THE 30 TO 50 PERCENT POPS IN PLACE FOR THE INTERIOR AND WEST COAST METRO AREAS THROUGH EARLY THIS EVENING...WITH ONLY A 20 PERCENT POPS OVER THE EAST COAST METRO AREAS OF SOUTH FLORIDA. THE TROUGH OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY TONIGHT OVER CENTRAL FLORIDA...BEFORE MOVING SLOWLY SOUTH INTO THE LAKE OKEECHOBEE AREA ON SATURDAY AND THROUGH SOUTH FLORIDA ON SUNDAY. THIS WILL KEEP THE STEERING FLOW OVER SOUTH FLORIDA IN A LIGHT NORTHEAST DIRECTION ALONG WITH THE SEA BREEZE DEVELOPMENT EACH DAY ALONG BOTH COAST. SO THE SCATTERED POPS WILL REMAIN OVER THE INTERIOR AND WEST COAST METRO AREAS WITH ISOLATED POPS OVER THE EAST COAST METRO AREAS EACH DAY THIS WEEKEND. THE THREAT OF THUNDER WILL ALSO BE FOCUS MAINLY OVER THE INTERIOR AND WEST COAST METRO AREAS EACH DAY THIS WEEKEND..BUT THE EAST COAST METRO AREAS COULD SEE A THUNDERSTORM OR TWO. THE 500 MB TEMP WILL ALSO REMAIN VERY COLD FOR THIS TIME OF YEAR IN THE -8C TO -9C OVER SOUTH FLORIDA. THIS WILL ALLOW FOR SOME OF THE STORMS EACH DAY THIS WEEKEND TO BECOME STRONG OVER SOUTH FLORIDA ESPECIALLY WHERE THE SEA BREEZES COLLIDE EACH DAY. THE PRIMARY IMPACTS FROM THE STRONG STORMS WILL MORE LIKELY BE LIGHTNING STRIKES, GUSTY WINDS, AND HAIL. SO WILL MENTION THIS IN THE AFTERNOON HWO PACKAGE. LONG TERM... THE TROUGH OF LOW PRESSURE WILL MOVE INTO THE FLORIDA KEYS EARLY NEXT WEEK BEFORE MOVING BACK UP INTO SOUTH FLORIDA FOR THE MIDDLE OF NEXT WEEK...AS AN UPPER LEVEL LOW DEVELOPS OVER THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR SOME DRIER AIR TO WORK INTO SOUTH FLORIDA FROM THE NORTH EARLY NEXT WEEK...BEFORE MOISTURE RETURNS TO THE AREA FOR MIDDLE OF NEXT WEEK. THEREFORE...THE POPS FOR EARLY NEXT WEEK HAVE BEEN LOWER TO SLIGHT CHANCE OVER MOST OF SOUTH FLORIDA EXCEPT LOW END CHANCE OVER THE WESTERN AREAS. FOR MIDDLE OF NEXT WEEK...THE POPS WILL REMAIN IN THE CHANCE CAT OVER SOUTH FLORIDA. AVIATION... A WEAK TROUGH IS TRYING TO MAKES ITS WAY INTO SOUTH FLORIDA THIS AFTERNOON. THIS SHOULD ACT TO ENHANCE CONVECTION IN THE WESTERN HALF OF THE AREA. THE SEA BREEZE WILL KEEP THE EAST COAST CLEAR OF MOST CONVECTION, ALTHOUGH AN ISOLATED SHOWERS MAY STILL TRY TO FORM. GIVEN THIS, HAVE KEPT ANY SHRA/TSRA OUT OF THE EASTERN SITES THIS AFTERNOON. FOR KAPF, HAVE DELAYED VCTS FOR A FEW HOURS AS THE MODELS INDICATE IT WILL BE MORE TOWARDS THE MID AFTERNOON BEFORE CONVECTION AFFECTS NAPLES. HOWEVER, THIS COULD BE OFF A LITTLE, SO VCTS MAY NEED TO ADDED, OR EVEN DELAYED SOME, BASED ON DEVELOPMENT. WINDS WILL BE GENERALLY EASTERLY THIS AFTERNOON, WITH THE EXCEPTION OF KAPF, WHERE THE GULF BREEZE IS EXPECTED TO JUST MAKE IT PAST THE AIRPORT. TONIGHT, WINDS WILL LIGHTEN AND GO VARIABLE IN MANY LOCATIONS. THEY WILL ONCE AGAIN BECOME EASTERLY TOMORROW BETWEEN 5 AND 10 KTS. MARINE... THE WINDS WILL REMAIN FROM THE EAST NORTHEAST AT 10 KNOTS OR LESS THIS WEEKEND INTO EARLY NEXT WEEK OVER ALL OF SOUTH FLORIDA WATERS. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS WILL BE GOOD OVER ALL OF SOUTH FLORIDA WATERS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 77 89 77 88 / 20 30 20 20 FORT LAUDERDALE 79 89 79 89 / 20 20 20 20 MIAMI 78 90 78 89 / 20 30 20 20 NAPLES 74 91 74 91 / 70 30 30 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...85/AG AVIATION/RADAR...17/ERA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1248 AM CDT THU SEP 5 2013 .DISCUSSION... 840 PM CDT FOR EVENING UPDATE... MAINLY ONLY MINOR ADJUSTMENTS BASED ON OBS/SATELLITE TRENDS THIS EVENING. SURFACE COLD FRONT WAS JUST ENTERING FAR NORTHEASTERN LAKE COUNTY IL AT 01Z PER SFC OBS AND EXTRAPOLATION OF BOUNDARY THAT WAS PROMINENT EARLIER IN KMKX REFLECTIVITY DATA. FRONT WILL CONTINUE TO BACK-DOOR ITS WAY ACROSS NORTHEAST IL THROUGH THE REMAINDER OF THE EVENING HOURS AND EVENTUALLY PUSHING INTO CENTRAL IL/IN OVERNIGHT. WHILE COOLER TEMPS WILL SPREAD IN BEHIND THE FRONT...IT APPEARS THE STRONGER COOLING/DRYING WILL LAG THE FRONT INTO THE DAY THURSDAY GIVEN MODEST NORTHEAST WINDS OVERNIGHT. TEMPS/HUMIDITY WILL ACTUALLY BE A LITTLE HIGHER BEHIND THE FRONT TONIGHT THAN LAST NIGHT. GOES 11-3.9 MICRON IR IMAGERY DOES INDICATE AREA OF LOW CLOUDS (1100-1400 FT BASES) DEVELOPING BEHIND THE FRONT FROM EASTERN WI INTO WESTERN LOWER MICHIGAN AT 01Z...THOUGH 18Z WRF-NAM SOUNDINGS AND TSECTS APPEAR TO HAVE BACKED OFF A BIT ON THE DEPTH OF MOISTURE THAT DEVELOPS OVER FAR NORTHERN/NORTHWESTERN IL BEHIND THE FRONT OVERNIGHT AS WELL AS AREA OF LIGHT PRECIP OVER NORTHWEST IL. 00Z RAOB ANALYSIS AT 925-850MB LEVELS DOES INDICATE LOW LEVEL THERMAL RIDGE ALONG IA/MN BORDER REGION THAT MAY CONTINUE TO SUPPORT SOME ASCENT ABOVE THE LOW LEVEL FRONTAL ZONE GIVEN STRONG NORTHWESTERLY JET AND PRESENCE OF SHEARED MID-LEVEL SHORT WAVE...SO AM A LITTLE HESITANT TO PULL CLOUDS/SPRINKLES OF GOING FORECAST. WILL SHIFT TIMING A COUPLE HOURS PAST MIDNIGHT BUT OTHERWISE LEAVE ALONE AT THIS POINT WITH LOCAL 8 KM WRF-ARW RUN ALSO STILL PRODUCING A LITTLE QPF OVER SOUTHWEST WI/NORTHWEST IL TOWARD MORNING. OTHERWISE...OTHER THAN ADJUSTMENTS TO HOURLY TEMP/WIND AND SKY COVER GRIDS NO OTHER SIGNIFICANT CHANGES MADE TO NEAR TERM OF FORECAST FOR THE OVERNIGHT HOURS. RATZER //PREV DISCUSSION... 300 PM CDT THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER. SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN. THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE SOUTHEASTWARD. TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT. LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND INCREASING CLOUD COVER ACTING AS INSULATION. THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE SW ADVECTION. MTF EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4 THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF THUNDERSTORMS IN THE EXTENDED PERIOD. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * FROPA TURNING WINDS TO THE NORTHEAST IN THE NEAR TERM...WITH AN INCREASE IN SPEED AND GUSTS THROUGH THE MORNING. * LOW END MVFR AND IFR CEILINGS POSSIBLE EARLY THIS MORNING. RODRIGUEZ //DISCUSSION...UPDATED 06Z... MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM...WITH WINDS TURNING TO THE NORTHEAST WITH A SLOW MOVING COLD FRONT AS WELL AS POTENTIAL FOR LOWER CEILINGS. LATEST OBSERVATIONS INDICATING A SLOW PROGRESSION OF THIS FRONT INTO NORTHEAST ILLINOIS...WITH WINDS SHIFTING TO THE NORTHEAST BUT STILL REMAINING ON THE LIGHTER SIDE. THIS TRANSITION TO THE NORTHEAST WILL OCCUR WITH ALL THE TERMINALS WITHIN THE NEXT 1-2 HOURS...WITH WINDS INITIALLY REMAINING LIGHT. THEN AS THE GRADIENT PICKS UP...SHOULD SEE AN INCREASE IN SPEEDS/GUSTS THROUGH THE REMAINDER OF THE MORNING. LATEST SATELLITE IMAGERY DEPICTING AREA OF LOW END MVFR/IFR CEILINGS INCREASING IN COVERAGE AS THEY SPILL SOUTH INTO NORTHEAST ILLINOIS. WITH THIS INCREASE IN COVERAGE AND SHORT TERM GUIDANCE SHOWING THIS LOW LEVEL MOISTURE MOVING ACROSS THE TERMINALS...HAVE INCLUDED A PERIOD OF LOWER CEILINGS EARLY THIS MORNING. ALTHOUGH...CONFIDENCE AS TO THE DURATION OF THE LOWER CEILINGS IS SOMEWHAT LOWER AS THESE LOW CLOUDS SHOULD REMAIN PROGRESSIVE WITHOUT ANY FURTHER EXPANSION ON THE BACKSIDE. WITH THE DEPARTURE OF THESE CLOUDS...EXPECT VFR CONDITIONS THROUGH THE REMAINDER OF THE FORECAST PERIOD. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION. * MEDIUM CONFIDENCE WITH CEILING TRENDS THIS MORNING. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR. WX NIL. SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT. SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR. MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR. TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR. KREIN && .MARINE... 229 PM CDT A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT. THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM FRIDAY. IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM THURSDAY TO 3 PM THURSDAY. && $$ 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 DES MOINES IA
1231 PM CDT THU SEP 5 2013 .SHORT TERM.../TODAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING. .LONG TERM.../TONIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS. MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A BIT. THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO. BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER. THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA. WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED. && .AVIATION...05/18Z ISSUED AT 1231 PM CDT THU SEP 5 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH NO PRECIPITATION FORECAST. THERE IS A CHANCE THAT LIGHT BR COULD FORM EARLY FRIDAY MORNING AROUND KMCW/KALO...BUT CONFIDENCE IS TOO LOW TO MENTION IN THE TAFS AT THIS TIME. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...SMALL AVIATION...LEE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
625 AM CDT THU SEP 5 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM.../TODAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING. .LONG TERM.../TONIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS. MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A BIT. THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO. BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER. THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA. WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED. && .AVIATION...05/12Z ISSUED AT 625 AM CDT THU SEP 5 2013 WEAK SHOWER ACTIVITY WILL CONTINUE TO DRIBBLE OVER WESTERN IOWA AND HAD HIGH ENOUGH CONFIDENCE TO LEAVE OUT ANY MENTION OF RAIN IN THE TAFS THIS MORNING. FOD IS LIKELY TO BE THE CLOSEST BUT IF ANYTHING DOES MAKE IT THAT FAR EAST IT WILL QUICKLY DISSIPATE WITH THE DEEP DRY LAYER BELOW 10KFT. OTHERWISE...VFR CONDITIONS ARE FORECAST THROUGH FRIDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...SMALL AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
356 AM CDT THU SEP 5 2013 .SHORT TERM.../TODAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING. .LONG TERM.../TONIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM CDT THU SEP 5 2013 MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS. MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A BIT. THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO. BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER. THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA. WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED. && .AVIATION...05/06Z ISSUED AT 1202 AM CDT THU SEP 5 2013 VFR CONDITIONS EXPECTED THROUGHOUT THE TAF FORECAST PERIOD. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...SMALL AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
317 PM CDT Thu Sep 5 2013 .SHORT TERM...(This Evening through Friday) Issued at 243 PM CDT THU SEP 5 2013 Upper level high remains centered over Colorado through tomorrow while a surface high continues to retreat eastward. An area of isolated showers has continued to move closer to our northern areas...although most of the precip is not reaching the ground. The 12z NAM supports moisture convergence in this area along with an axis of slight elevated instability which extends into northeast Kansas. The HRRR has also been consistent with bringing these showers into our area. If showers are able to persist within the dry air and weak advection only northern row of counties look to be affected the next few hours with an overall diminishing trend towards the evening. High temperatures look to reach the low to mid 90s today which is above normal for this time of year. The skies will remain partly cloudy especially across northern areas closer to the ongoing shower activity. Tonight WAA will again set up across eastern Nebraska well north of the northeast Kansas to keep the entire area dry. Low temperatures tonight appear to be on track for the mid to upper 60s. Low level winds will gradually veer allowing warming 850 temps to spread into eastern KS therefore high temperatures will make it into the low to mid 90s again tomorrow. With more mixing likely tomorrow during the day winds will likely increase to around 10 mph with gusts up to 20 mph possible. .LONG TERM...(Friday Night through Thursday) Issued at 243 PM CDT THU SEP 5 2013 The forecast for Friday night through Tuesday is essentially one of persistence. Other than subtle day to day differences, the weather pattern will be fairly stagnant through the period with a large area of upper level high pressure slowly drifting from west to east across the plains and into the Ohio valley. High temperatures will be consistently in the 90s. The hottest day currently appears to be Saturday with southwest surface winds, the upper ridge almost directly overhead, and the warmest 850 temps of the week in place all pointing to highs in the middle to upper 90s. There will be a couple of very weak upper disturbances that may provide enough lift for a shower or thunderstorm, mainly northeast of the local forecast area along a weak convergence zone, late on Saturday. Will watch these features in future forecasts but expect dry conditions for the most part through the weekend. There are a couple of stronger northern stream short wave troughs that come over the top of the ridge next week. The trough crossing the Dakotas on Monday will push a cold front to the south, but expect this front to lose its forward progression and stall over northern Nebraska. The second of the stronger troughs will cross the Dakotas late Tuesday and should successfully push the cold front through the forecast area by late Wednesday. Much of the upper forcing will remain well to the north, and surface convergence is not expected to be particularly strong, but may be sufficient for scattered storms along the incoming front. Cooler and drier air with almost meridional flow aloft will follow the frontal passage and expect the end of next week to be both cooler and dry. && .AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon) Issued at 1233 PM CDT THU SEP 5 2013 VFR conditions are expected through the taf period. Winds will remain under 10 kts and gradually veer to the south through the period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sanders LONG TERM...Barjenbruch AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS TOPEKA KS
134 PM CDT Thu Sep 5 2013 .UPDATE... Issued at 120 PM CDT THU SEP 5 2013 An area of showers with isolated thunder has continued to develop across south central Nebraska. The 12z NAM shows that there has been moisture convergence in this area along with an axis of slight elevated instability which extends into northeast Kansas. The HRRR has also been consistent with bringing these showers into our area. These showers only look to affect the row of counties along the NE/KS state line during the afternoon hours. Therefore...have increased the pops and mentioned isolated showers and thunder until 7pm this evening in the latest forecast update. && .SHORT TERM...(Today and Tonight) Issued at 301 AM CDT THU SEP 5 2013 Upper level pattern remains nearly locked in place with upper high centered over the Rockies and modest but widespread 500mb height rises across the bulk of the CONUS. Mid levels again showing a stronger though still not impressive temperature gradient across Nebraska from west to east, with much drier conditions to the south. Diurnal upswing in isolated to scattered convection again taking place in eastern Nebraska in recent hours. Moisture is a bit richer than that of Wednesday morning, but again support for continued precipitation this far downstream diminishes quickly. Anything more than very isolated coverage of measurable precip seems unlikely. Higher level cloud to again spread across eastern Kansas today with low levels continuing to warm a bit and should support highs a bit above Wednesday`s levels. Mid level WAA regime sets up again to the north tonight, though not quite as robust as current conditions and will keep any precip mention out. .LONG TERM...(Friday through Wednesday) Issued at 301 AM CDT THU SEP 5 2013 As the upper ridge advances eastward, so does the warmup that comes along with it. 850mb temps in the 21-24C range rise to 22-26 Saturday into Sunday with the warmest west and north. Strong push of cold air dropping into the Great Lakes comes toward the forecast area from the east by Sunday morning, but think warm air in place and strength of the ridging will keep precip chances east of our area. A hot late week into weekend with highs in the middle 90s quite common across the entire area. Start to see a pattern shift into next week as the upper trof over the west coast rides across the northern periphery of the ridge on Monday. This sets up a front across the northern plains, and speed to which it can advance to the south will impact temperature and precipitation forecasts for mid week. At this time, Monday looks to remain warm as the thermal ridge is driven to flatten to more of a SW to NE orientation and leaves warm temperatures over the state, and would bring another day with highs well into the 90s. Would expect similar conditions Tuesday as front knocks on the KS NE border by late Tuesday afternoon. EC showing better signs of a break in the hot pattern, along with the GFS, and now has a stronger shortwave trof dropping southward across the Rockies and reinforces a southern push for the front. Boundary would come through sometime on Wednesday and finally have cooler highs forecast and precip chances in the forecast. && .AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon) Issued at 1233 PM CDT THU SEP 5 2013 VFR conditions are expected through the taf period. Winds will remain under 10 kts and gradually veer to the south through the period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Sanders SHORT TERM...65 LONG TERM...67 AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1135 AM MDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 250 AM MDT THU SEP 5 2013 STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY SURFACE FLOW. NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 250 AM MDT THU SEP 5 2013 THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER 90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID 80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1133 AM MDT THU SEP 5 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. GUSTS TO NEAR 20 KNOTS THIS AFTERNOON WILL END NEAR SUNSET. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DLF LONG TERM...ALW AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
522 AM MDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 250 AM MDT THU SEP 5 2013 STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY SURFACE FLOW. NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 250 AM MDT THU SEP 5 2013 THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER 90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID 80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 511 AM MDT THU SEP 5 2013 VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. UPPER LEVEL HIGH PRESSURE CENTERED OVER EASTERN COLORADO/WESTERN KANSAS WILL BRING MOSTLY CLEAR CONDITIONS...WITH A FEW HIGH CLOUDS OVER BOTH TAF SITES. LIGHT SOUTHERLY WINDS THIS MORNING WILL INCREASE TO AROUND 10 TO 15 KTS MID-DAY FOR BOTH SITES AS MIXING TAKES PLACE...WITH WIND GUSTS AROUND 20 TO 25 KTS. GUSTS SHOULD DECREASE AROUND SUNSET WITH SUSTAINED WINDS AROUND 10KTS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DLF LONG TERM...ALW AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
520 AM MDT THU SEP 5 2013 .UPDATE... ISSUED AT 517 AM MDT THU SEP 5 2013 REMOVED POPS/THUNDERSTORMS FROM NORTHERN TIER OF COUNTIES FOR EARLY THIS MORNING. CONVECTION THAT WAS PERSISTENT OVERNIGHT ACROSS EXTREME NORTHEAST COLORADO AND PARTS OF SOUTHWEST NEBRASKA HAS FINALLY DISSIPATED. && .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 250 AM MDT THU SEP 5 2013 STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY SURFACE FLOW. NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 250 AM MDT THU SEP 5 2013 THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER 90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID 80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1121 PM MDT WED SEP 4 2013 VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24 HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DLF SHORT TERM...DLF LONG TERM...ALW AVIATION...FS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
255 AM MDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 250 AM MDT THU SEP 5 2013 STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY SURFACE FLOW. NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 250 AM MDT THU SEP 5 2013 THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER 90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID 80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1121 PM MDT WED SEP 4 2013 VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24 HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DLF LONG TERM...ALW AVIATION...FS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 PM EDT THU SEP 5 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 410 PM EDT THU SEP 5 2013 WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW THROUGH THE GREAT LAKES BETWEEN A TROUGH OVER NE CANADA AND A RIDGE FROM COLORADO INTO THE WRN PLAINS. THE MAIN UPSTREAM SHORTWAVE TROUGH OF INTEREST WAS MOVING INTO WEST CENTRAL SASK. AT THE SFC...HIGH PRES WAS CENTERED OVER MI AND THE WRN GREAT LAKES BRINGING CLEAR SKIES AND LIGHT WINDS TO THE REGION. TONIGHT...MAINLY CLEAR SKIES THIS EVENING ARE EXPECTED TO GIVE WAY TO INCREASING MID/HIGH CLOUDS LATE. TEMPS MAY DROP OFF QUICKLY AFTER SUNSET BUT WITH INCREASING SW FLOW OVERNIGHT...TEMPS ARE EXPECTED TO ONLY DROP TO AROUND CENTRAL 50 AND BECOME STEADY OR SLOWLY RISING IN THE MID TO UPPER 50S WEST. FRIDAY...THE SASK SHRTWV IS EXPECTED TO SLIDE JUST NORTH OF LAKE SUPERIOR. HOWEVER...925-700 MB THETA-E ADVECTION AHEAD OF THIS FEATURE AND ASSOCIATED 310K ISENTROPIC LIFT WILL SUPPORT SCT ELEVATED SHRA/TSRA INTO N AND W LAKE SUPERIOR BY LATE MORNING THAT MAY SPREAD INTO THE CNTRL AND EAST DURING THE AFTERNOON. THERE IS STILL ENOUGH UNCERTAINTY WITH MDLS DIFFERING ON TIMING/POSITION OF THE PCPN TO KEEP JUST CHANCE POPS. ALTHOUGH MUCAPE VALUES TO AROUND 1K J/KG RANGE MAY SUPPORT SOME STRONGER STORMS...THE GREATER INSTABILITY WITH MLCAPES OF 1000-1500 J/KG IS EXPECTED TO REMAIN UPSTREAM OVER MN. EVEN WITH INCREASING CLOUDS AND PCPN POSSIBLE DURING THE AFTERNOON...HIGH TEMPS SHOULD CLIMB INTO THE LOWER 80S. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 410 PM EDT THU SEP 5 2013 MAIN FCST CONCERNS IN THE LONGER TERM REVOLVE ARND POPS ON FRI NGT/SAT ASSOCIATED WITH PASSAGE OF SHRTWVS IN NW FLOW ALF BTWN THE MEAN TROF OVER QUEBEC AND RIDGE IN THE PLAINS. FOCUS FOR LATER IN THE WEEKEND TURNS TOWARD HI PRES BLDG INTO THE UPR LKS. FRI NGT/SAT...A SHRTWV EMBEDDED IN THE NW FLOW ALF IS PROGGED TO PASS NEAR THE UPR LKS IN THE EVNG...SO EXPECT THE BEST CHC OF SHRA/TS TO BE IN THE EVNG WHEN ACCOMPANYING PVA INTERACTS WITH AXIS OF HIER H85 THETA E. MID LVL DRYING/NEGATIVE H85 THETA E AVCTN IN THE WAKE OF THIS INITIAL SHRTWV PASSAGE WL THEN RESULT IN DIMINISHING POPS NW-SE THRU SAT MRNG...BUT APRCH OF ANOTHER SHRTWV IN THE NW FLOW ALF WARRANTS AT LEAST A SCHC OF LINGERING SHRA. THE 12Z GFS AND ESPECIALLY THE 00Z CNDN MODELS ARE SLOWER/STRONGER THAN THE BULK OF THE OTHER GUIDANCE WITH THIS TRAILING DISTURBANCE...LINGERING DEEP LYR QVECTOR CNVGC AND QPF THRU MOST OF THE DAY ON SAT...SO RETAINED SOME LO CHC POPS ESPECIALLY OVER THE SCENTRAL THRU THE ENTIRE DAY. SAT NGT THRU SUN...CNDN HI PRES UNDER CONFLUENT NW FLOW ALF BTWN THE TROF IN QUEBEC/RDG IN THE PLAINS IS PROGGED TO SHIFT FM MANITOBA AT 00Z SUN TO OVER LK SUP SUN AFTN. UNDER LARGER SCALE SUBSIDENCE AND PWAT FCST AOB 0.50 INCH...DRY WX WL PREVAIL. THE ONLY CONCERN IS WHETHER THERE WL BE ANY LO CLDS AT LEAST FOR A TIME NEAR LK SUP WITH UPSLOPE NNE FLOW UNDER SHARP SUBSIDENCE INVRN H85-9 IN ADVANCE OF THE INCOMING SFC HI AS SUGGESTED BY THE 06Z AND 12Z GFS RUNS. GIVEN LARGE SCALE ACYC LLVL FLOW...DRY NATURE OF INCOMING AIRMASS AND MARGINAL CHILL OF THIS AIRMASS FOR LK CLDS /H925 TEMPS NO LOWER THAN 6-7C OVER THE E HALF COMPARED TO OPEN WATER TEMPS 14-15C/... RESTRICTED FCST OF SCT-BKN LO CLDS TO THE HIER TERRAIN OF THE NCENTRAL EARLY SUN MRNG PER THE MORE PESSIMISTIC GFS FCST SDNGS AND BEFORE DAYTIME HEATING WOULD MIX THESE CLDS OUT ON SUN AFTN. TEMPS ON SUN MRNG/AFTN WL BE COOLER THAN THE DAY BEFORE WITH H85 TEMPS FCST BTWN 5-10C DURING THIS PERIOD. EXPECT THE LOWEST MIN TEMPS ON SUN MRNG OVER THE INTERIOR W...WITH NNE FLOW OFF LK SUP KEEPING AREAS NEAR THE SHORE WARMER. SUN NGT...AS SFC HI PRES DRIFTS OVER NY STATE BY 12Z SUN...A RETURN SLY FLOW OF WARMER/MOISTER AIR BTWN THIS FEATURE AND A SHRTWV/ ACCOMPANYING SFC LO MOVING INTO THE NRN PLAINS WL DVLP OVER THE UPR LKS. SO EXPECT AT LEAST SOME INCRS IN CLDS AND A WARMER OVERNGT. RESTRICTED POPS TO THE FAR WRN CWA GIVEN MODEL QPF/LINGERING LLVL DRY AIR OVER MOST OF THE CWA. MON INTO TUE...AS SHRTWV IN THE NRN PLAINS AND ATTENDANT SFC LO PRES/ WARM FNT MOVE TOWARD THE UPR LKS...EXPECT SHRA/TS CHCS TO INCRS OVER THE CWA. NOT SURPRISINGLY...THE EXTENDED MODELS DISAGREE ON THE EXACT TRACK OF THE SFC LO/WARM FNT AND AXIS OF HIER QPF. THE 12Z AND ESPECIALLY THE 00Z CNDN MODELS ARE FARTHER N WITH THE SFC LO TRACK/ WARM FNT AND FCSTS THE BULK OF ANY ACCOMPANYING SHRA/TS TO REMAIN N OF UPR MI WHILE THE 06Z GFS FCSTS HEAVY PCPN WITH THE SFC LO TRACKING E THRU THE CWA OVER THE WARM FNT ON MON INTO EARLY TUE. THE RESULT OF THIS SCENARIO WOULD BE A WARM SUMMER-LIKE DAY WITH A GOOD DEAL OF SUNSHINE AND H85/SFC TEMPS NEAR 20C/WELL INTO THE 80S AWAY FM LK MODERATION IN LLVL SW FLOW. SHRA/TS WITH HEAVY RA/PSBL SEVERE TS WOULD BE THE RESULT IF THE GFS MODEL VERIFIES. THE 12Z GFS/00Z ECWMF RUNS ARE A COMPROMISE BTWN THOSE TWO CAMPS AND ALSO INDICATE THE POTENTIAL FOR SEVERE TS WITH FCST H85 TEMPS UP TO 20C AND SSI AS LO AS -3 TO -4C UNDER STRONGER H5 FLOW. GIVEN THESE UNCERTAINTIES... MAINTAINED CONSENSUS FCST FOR NOW. EXTENDED...AS AN UPR TROF DEEPENS INTO THE GREAT LKS ON WED BEHIND DEPARTING SHRTWV RESPONSIBLE FOR THE MON/TUE POPS...EXPECT SHRA/TS CHCS TO PERSIST. EXPECT COOLER/DRIER WX TO SPREAD TO THE E NEXT THU/FRI AS HI PRES BLDS TOWARD THE PLAINS/WRN GRT LKS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 131 PM EDT THU SEP 5 2013 WITH HIGH PRESSURE OVER THE REGION...EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGH MOST OF TONIGHT. MID CLOUDS WILL BEGIN TO THICKEN AFTER MIDNIGHT AT CMX...BUT ANY SHOWERS AND THUNDERSTORMS ARE EXPECTED TO HOLD OFF UNTIL FRIDAY AFTERNOON. CONFIDENCE IN THE SHA/TSRA ARRIVAL TIME AND PROBABILITY WAS LOW SO NONE MENTIONED THROUGH 18Z/FRI. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 410 PM EDT THU SEP 5 2013 EXPECT SW WINDS UP TO 20-25 KTS ON FRI UNDER SHARPENING PRES GRADIENT AHEAD OF INCOMING LO PRES TROUGH. FOLLOWING THE PASSAGE OF A COLD FRONT ON SAT...WINDS WILL VEER TO THE N-NE AND REMAIN UP TO 20 KTS INTO SUN IN ADVANCE OF HI PRES BUILDING TOWARD THE GREAT LAKES. A RELATIVELY WEAK PRES GRADIENT AND/OR HI OVERWATER STABILITY WILL THEN DOMINATE ON SUN INTO TUE...RESULTING IN WINDS UNDER 20 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...KC AVIATION...JLB MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 AM EDT THU SEP 5 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 407 PM EDT WED SEP 4 2013 WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL THROUGH THE UPPER GREAT LAKES BETWEEN A LOW OVER NRN QUEBEC AND A RIDGE FROM COLORADO THROUGH THE WRN PLAINS. WITH CONFLUENT FLOW AND 700-300 MB QVECTOR DIV BUILDING INTO THE AREA...EXPECT MAINLY CLEAR SKIES TO PREVAIL WITH ONLY SOME BANDS OF CIRRUS THROUGH THE ERN CWA...PER VIS IMAGERY. AT THE SFC...HIGH PRES FROM SRN MANITOBA INTO NW ONTARIO WAS BUILDING INTO THE NRN GREAT LAKES WITH INFLUX OF DRY AIR ON NRN ACYC FLOW. LOWER DEWPOINTS UPSTREAM FROM LAKE SUPERIOR (READINGS IN THE UPPER 30S) WERE FILTERING TOWARD UPPER MI. TONIGHT...EVEN WITH PWAT VALUES AROUND 0.50 INCH CLIMBING TO NEAR 0.75 INCH...WITH HIGH PRES BUILDING INTO UPPER MI...MOSTLY CLEAR SKIES AND LIGHT WINDS ALLOW TEMPS TO DROP OFF TOWARD THE LOWER END OF GUIDANCE. READINGS INTO THE UPPER 30S INLAND WEST AND LOW TO MID 40S OVER THE EAST AND ALONG THE GREAT LAKES ARE EXPECTED. PATCHY FROST MAY BE POSSIBLE IN THE TYPICAL COLD SPOTS FROM REPUBLIC AND CHAMPION TO AMASA...IRON RIVER AND WATERSMEET. THURSDAY...UNDER ABUNDANT SUNSHINE WITH 850 MB TEMPS IN THE 6C TO 10C RANGE...TEMPS WILL REBOUND CLOSER TO SEASONAL AVERAGES WITH HIGHS RANGING FROM THE UPPER 60S EAST TO THE LOWER 70S WEST. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 407 PM EDT WED SEP 4 2013 HIGH PRESSURE WILL KEEP WEATHER QUIET THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON. AS THE HIGH CENTERS OVER THE EASTERN SEABOARD...UPPER MICHIGAN IS POSITIONED ON THE NORTHWESTERN PERIPHERY OF THE RIDGE...MAKING US VULNERABLE FOR WEAK WAVES TO SLIDE THROUGH. THE FIRST OF THESE SLIDES OUT AHEAD OF THE MAIN TROUGH ON FRIDAY AFTERNOON. MODELS ARE MOSTLY IN AGREEMENT...WITH THE EXCEPTION OF THE GFS WHICH BRINGS THE MAIN TROUGH IN MUCH QUICKER...SO STRAYED FROM THAT SOLUTION. USED PRIMARILY THE GEM/ECMWF FOR THIS LONG TERM FORECAST. WEAK MOISTURE ADVECTION/CONVERGENCE SHOWS UP FOR THE MID LEVELS AND FOCUSES ACROSS THE WEST AND NORTHERN PORTIONS OF THE CWA EARLIER IN THE DAY...PRIMARILY OVER THE KEWEENAW AND LAKE SUPERIOR. THROUGHOUT THE DAY THIS REGION MOVES EAST-SOUTHEASTWARD TOWARDS QUEBEC...SO KEPT PCP CHANCES FAR EAST INTO FRIDAY EVENING. OVERALL...850-500MB QVECTOR CONVERGENCE IS PALTRY BUT WARRANTS SOME SLIGHT CHANCE/CHANCE POPS. LOW LEVELS ARE FAIRLY DRY THOUGH...AND INSTABILITY IS MINIMAL. WILL KEEP THE POPS PRIMARILY OVER THE LAKE AND FAR EAST FOR NOW. FRIDAY NIGHT THROUGH SATURDAY THE STRONGER TROUGH MOVES THROUGH THE GREAT LAKES AS LOW PRESSURE OVER JAMES BAY ON FRIDAY MOVES INTO QUEBEC. MOISTURE IS DEEPER AND INSTABILITY IS GREATER THIS GO AROUND...WHICH WILL SUPPORT SHOWERS AND TSTORMS ACROSS THE CWA. THE WESTERN CWA IS LIKELY TO SEE SHOWERS/A FEW TSTORMS STARTING LATER FRIDAY NIGHT AND CONTINUING THROUGH MAINLY SATURDAY MORNING. WITH GREATER INSTABILITY BUILDING TOWARDS SATURDAY AFTERNOON ALONG THE WI BORDER AND CENTRAL U.P. LINGERED CHANCE POPS THERE THROUGH THE AFTERNOON. THE BEST MOISTURE IS CENTRAL AND EAST HOWEVER...AND SFC BASED CAPE IS AROUND 1000-500 J/KG FOR THE AFTERNOON. WITH THE FRONT PASSING THROUGH THE CENTRAL CWA AROUND 18Z AND NORTHWEST FLOW ALOFT...EXPECT WE WILL SEE SOME ACTIVITY. 0-6KM BULK SHEAR IS AROUND 20-30 KNOTS...SO DO NOT EXPECT ANYTHING TOO GET TOO ORGANIZED. ANY SEVERE THREAT AS OF RIGHT NOW LOOKS TO BE VERY ISOLATED. ON SUNDAY HIGH PRESSURE BRINGS A BRIEF BREAK TO THE PRECIPITATION. MONDAY AND TUESDAY A WARM FRONT LIFTS ACROSS THE MIDWEST WITH A STRONGER LOW PRESSURE SYSTEM IN THE NORTHERN PLAINS. THIS LOW WILL MOVE NORTHEASTWARD INTO ONTARIO...AND EVENTUALLY BRING A COLD FRONT ACROSS UPPER MI ON WEDNESDAY. HAVE CHANCE POPS IN THE FORECAST FOR NOW...GIVEN DIFFERENCES BETWEEN MODELS IN THE LOCATION OF THE LOW PRESSURE SYSTEM DURING THESE TIMES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 144 AM EDT THU SEP 5 2013 WITH HIGH PRESSURE BUILDING INTO THE REGION...EXPECT VFR CONDITIONS AND LIGHT WINDS THROUGH THE FCST PERIOD. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 407 PM EDT WED SEP 4 2013 WITH HIGH PRES BUILDING INTO THE UPPER LAKES...WINDS WILL DIMINISH TO LESS THAN 20 KTS LATER TONIGHT INTO THURSDAY. SW WINDS WILL INCREASE ON FRIDAY IN THE TIGHTER PRESSURE GRADIENT BETWEEN THE EXITING HIGH PRESSURE AND A COLD FRONT THAT ARRIVES THIS WEEKEND. EXPECT WINDS ON FRIDAY TO STAY LESS THAN 25 KTS. WINDS FOR THE REMAINDER OF THE FORECAST PERIOD WILL REMAIN LESS THAN 20 KNOTS DUE TO WEAKER PRESSURE GRADIENT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...MCD AVIATION...VOSS MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1236 PM CDT Thu Sep 5 2013 .SHORT TERM...(Today through Saturday) Issued at 410 AM CDT THU SEP 5 2013 At 8z water vapor imagery and RAP analysis continue to indicate a strong 596 hpa H5 ridge over the interior mountain region of the CONUS, with a deep trough over the Hudson Bay area. Between these two features light northwest flow continues in the mid levels. At 8z water vapor as well as IR imagery indicated an area of mid level clouds rounding the northwest quadrant of the mid level ridge across far eastern Nebraska and far western Iowa. Radar imagery indicates that there are a few showers associated with this area of clouds. These showers, with an isolated lightning strike or two are likely associated with a very weak and subtle impulse rounding the mid level ridge. Today`s forecast will depend on how many clouds this subtle wave will form through the day. The current thought is that these showers will likely not make it as far south as Interstate 70, although a few light sprinkles or showers may affect the far northern and western portions of Missouri and extreme NE Kansas. As the trough moves through it looks as though it will bring with it some mid level cloud cover, especially in the western half of the forecast area. These mid level clouds could act to keep temperatures a bit cooler than the going forecast suggested. Have gone with a dry forecast for today, and dropped temperatures 1-3 degrees in the western half of the CWA for day time highs. Even though perhaps slightly cooler temps are expected day time highs will still make it into the mid to upper 80s, but will continue to monitor the diurnal trend and adjust based on how the cloud cover behaves. For the rest of the mid range forecast expect dry conditions to remain, as the mid level ridge continues to shunt any strong chance for rain well north of the forecast area. With the steady flow of southerly winds into the area as well as the mid level ridge keeping the area clear of any significant cloud cover or rain expect a steady warm up through the weekend, with daytime highs reaching the lower 90s for Friday, and rising into the lower to mid 90s for Saturday and Sunday. The only chance for rain in the forecast area through the weekend will be a minimal chance for an isolated shower or two across NC/NE Missouri Saturday night into Sunday morning. .LONG TERM...(Sunday through Wednesday) Issued at 410 AM CDT THU SEP 5 2013 Well above average temperatures will continue into the extended time period however models are hinting at a potential pattern change toward the end of the period. These well above above average temperatures have been courtesy of an upper level ridge of high pressure that has been dominating the regions weather. This will also be the case at the onset of the extended period as the upper level ridge axis will reside over the central Plains. Sunday an upper level shortwave will be rounding this ridge and models indicate that an overnight MCS will develop over Iowa and roll into the eastern portion of the CWA Sunday morning. As such have added slight chance POPs to the eastern CWA with slightly cooler temperatures around 90 across the eastern CWA. Temperatures elsewhere across the CWA will reach into the mid 90s. Monday will be the warmest day in the extended time frame as the upper level ridge axis moves directly overhead. Highs will reach into the mid 90s CWA wide. However, Monday night an upper level trough will move through the northern Plains into the Upper Midwest. This will force a weak cold front towards the area however, it will initially get hung up north of the CWA. It will also flatten the upper level ridge across the area and force it into the southeastern CONUS. This will make for a "cooler" Tuesday with highs in the low to mid 90s. Tuesday night a second upper level trough will dig into the northern Plains. Models differ on the strength of the trough as the EC is much stronger with it than the GFS or GEM. In either case, the aforementioned cold front that was hung up north of the area will be forced into the CWA Tuesday night. This will have a two-fold effect: First, it will bring the next chance for showers and thunderstorms to the area Tuesday night into Wednesday. Second, it will cool temperatures into the mid to upper 80s. && .AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon) Issued at 1235 PM CDT THU SEP 5 2013 VFR conditions look to prevail at the terminals again overnight with the possible exception of KSTJ. Wind will likely go calm overnight, but expect to only have surface restriction in the River Valley near the KSTJ terminal during the early morning hours. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Leighton LONG TERM...73 AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
411 AM CDT Thu Sep 5 2013 .SHORT TERM...(Today through Saturday) Issued at 410 AM CDT THU SEP 5 2013 At 8z water vapor imagery and RAP analysis continue to indicate a strong 596 hpa H5 ridge over the interior mountain region of the CONUS, with a deep trough over the Hudson Bay area. Between these two features light northwest flow continues in the mid levels. At 8z water vapor as well as IR imagery indicated an area of mid level clouds rounding the northwest quadrant of the mid level ridge across far eastern Nebraska and far western Iowa. Radar imagery indicates that there are a few showers associated with this area of clouds. These showers, with an isolated lightning strike or two are likely associated with a very weak and subtle impulse rounding the mid level ridge. Today`s forecast will depend on how many clouds this subtle wave will form through the day. The current thought is that these showers will likely not make it as far south as Interstate 70, although a few light sprinkles or showers may affect the far northern and western portions of Missouri and extreme NE Kansas. As the trough moves through it looks as though it will bring with it some mid level cloud cover, especially in the western half of the forecast area. These mid level clouds could act to keep temperatures a bit cooler than the going forecast suggested. Have gone with a dry forecast for today, and dropped temperatures 1-3 degrees in the western half of the CWA for day time highs. Even though perhaps slightly cooler temps are expected day time highs will still make it into the mid to upper 80s, but will continue to monitor the diurnal trend and adjust based on how the cloud cover behaves. For the rest of the mid range forecast expect dry conditions to remain, as the mid level ridge continues to shunt any strong chance for rain well north of the forecast area. With the steady flow of southerly winds into the area as well as the mid level ridge keeping the area clear of any significant cloud cover or rain expect a steady warm up through the weekend, with daytime highs reaching the lower 90s for Friday, and rising into the lower to mid 90s for Saturday and Sunday. The only chance for rain in the forecast area through the weekend will be a minimal chance for an isolated shower or two across NC/NE Missouri Saturday night into Sunday morning. .LONG TERM...(Sunday through Wednesday) Issued at 410 AM CDT THU SEP 5 2013 Well above average temperatures will continue into the extended time period however models are hinting at a potential pattern change toward the end of the period. These well above above average temperatures have been courtesy of an upper level ridge of high pressure that has been dominating the regions weather. This will also be the case at the onset of the extended period as the upper level ridge axis will reside over the central Plains. Sunday an upper level shortwave will be rounding this ridge and models indicate that an overnight MCS will develop over Iowa and roll into the eastern portion of the CWA Sunday morning. As such have added slight chance POPs to the eastern CWA with slightly cooler temperatures around 90 across the eastern CWA. Temperatures elsewhere across the CWA will reach into the mid 90s. Monday will be the warmest day in the extended time frame as the upper level ridge axis moves directly overhead. Highs will reach into the mid 90s CWA wide. However, Monday night an upper level trough will move through the northern Plains into the Upper Midwest. This will force a weak cold front towards the area however, it will initially get hung up north of the CWA. It will also flatten the upper level ridge across the area and force it into the southeastern CONUS. This will make for a "cooler" Tuesday with highs in the low to mid 90s. Tuesday night a second upper level trough will dig into the northern Plains. Models differ on the strength of the trough as the EC is much stronger with it than the GFS or GEM. In either case, the aforementioned cold front that was hung up north of the area will be forced into the CWA Tuesday night. This will have a two-fold effect: First, it will bring the next chance for showers and thunderstorms to the area Tuesday night into Wednesday. Second, it will cool temperatures into the mid to upper 80s. && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1154 PM CDT WED SEP 4 2013 Nothing has changed from the previous discussion with VFR and light southeast winds prevailing. KSTJ and river valleys across northern and west central MO can expect patchy fog...with intermittent IFR visibilities at KSTJ due to local effects...forming during the pre- dawn hours and quickly dissipating after sunrise. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Leighton LONG TERM...73 AVIATION...MJ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
622 PM CDT FRI SEP 6 2013 .SYNOPSIS... ISSUED AT 334 PM CDT FRI SEP 6 2013 UPPER LEVEL HIGH PRESSURE...REMAINS STATIONARY OVER NERN COLORADO ATTM WITH RIDGING EXTENDING NORTH INTO SOUTHERN SASKATCHEWAN. LOW PRESSURE ALOFT WAS PRESENT OVER SOUTH CENTRAL WASHINGTON STATE...WITH ANOTHER UPPER LEVEL LOW OFF THE COAST OF NRN QUEBEC. AT THE SURFACE...LOW PRESSURE WAS PRESENT OVER SOUTH CENTRAL SOUTH DAKOTA WITH A WEAK SURFACE TROUGH EXTENDING SSW FROM THIS FEATURE INTO THE SRN PANHANDLE AND NERN COLORADO. WITH THE EXCEPTION OF THE NORTHEASTERN NEBRASKA PANHANDLE...SKIES WERE MOSTLY CLEAR WITH 3 PM CDT TEMPERATURES RANGING FROM 94 AT ONEILL TO 105 AT IMPERIAL. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 334 PM CDT FRI SEP 6 2013 HOT THIS AFTERNOON...WITH NEAR RECORD OR RECORD HIGH TEMPERATURES ACROSS WESTERN NEBRASKA. THE CENTER OF THE UPPER LEVEL HIGH PRESSURE IS ACROSS SOUTHWEST NEBRASKA...AND WILL MIGRATE SLOWLY SOUTHEAST INTO EASTERN KANSAS BY SUNDAY EVENING. AN ISOLATED THUNDERSTORM IS POSSIBLE ACROSS NORTHWEST NEBRASKA THIS EVENING...WHERE A WEAK DISTURBANCE WILL MIGRATE NORTHEAST AROUND THE PERIPHERY OF THE UPPER LEVEL HIGH PRESSURE CENTER. LOWS TONIGHT WILL AGAIN BE COMFORTABLE IN THE LOWER TO MID 60S MOST LOCALS DUE TO DRY AIR IN PLACE. A WEAK COLD FRONT WILL DROP INTO NORTHERN NEBRASKA SATURDAY...BUT CONTINUED SUBSIDENCE AND WARM AIR ALOFT SHOULD KEEP ANY THUNDERSTORMS AT BAY ALONG THE FRONT. ANOTHER HOT DAY...ESPECIALLY SOUTH OF THE FRONT ACROSS SOUTHWEST NEBRASKA...WHERE HIGHS IN THE UPPER 90S TO 102 DEGREES ARE EXPECTED. SOMEWHAT COOLER ACROSS NORTHERN NEBRASKA...WITH HIGHS IN THE LOWER TO MID 90S NORTH OF THE FRONT. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 334 PM CDT FRI SEP 6 2013 SATURDAY NIGHT THROUGH MONDAY NIGHT...TEMPERATURES SUNDAY AND MONDAY...ALONG WITH PRECIPITATION CHANCES MONDAY NIGHT ARE THE MAIN FORECAST CHALLENGES IN THE MID RANGE PERIODS. FOR SATURDAY NIGHT...SURFACE HIGH PRESSURE WILL TRACK FROM WESTERN ONTARIO INTO THE NORTHERN GREAT LAKES. THE STALLED OUT FRONTAL BOUNDARY OVER THE CENTRAL FCST AREA...WILL BEGIN TO LIFT NORTH AS A WARM FRONT OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. AT THE SAME TIME... SURFACE LOW PRESSURE...ALONG A COLD FRONT...WILL DEEPEN ACROSS THE WESTERN NEBRASKA PANHANDLE AND EASTERN WYOMING...LEADING TO INCREASED SOUTHERLY WINDS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA FOR SUNDAY. H85 TEMPS RANGING FROM 30 TO 33C WILL SURGE NORTH INTO SRN SD SUNDAY AFTERNOON...LEADING TO YET ANOTHER DAY OF 90S TO NEAR TRIPLE DIGIT HEAT ACROSS THE FORECAST AREA. HIGHS WILL RANGE FROM THE MIDDLE 90S INT THE NORTHEASTERN CWA...TO AROUND 100 IN THE SOUTHWESTERN FORECAST AREA. FOR SUNDAY THE RECORD HIGH FOR NORTH PLATTE IS 99 DEGREES...AND THERE IS A DECENT CHANCE FOR THIS RECORD TO BE TIED OR BROKEN. FOR SUNDAY NIGHT...TSRAS REMAIN POSSIBLE INVOF THE STALLED OUT FRONT OVER THE NERN NEBR PANHANDLE. MID AND UPPER LEVEL SUPPORT FOR PRECIPITATION WILL BE BEST ALONG THE FRONTAL BOUNDARY...AND OFF TO THE WEST OVER THE CENTRAL AND NRN ROCKIES...SO WITH THE EXCEPTION OF THE NRN PANHANDLE...A DRY FCST CONTINUES. ON MONDAY...AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL LIFT EAST ACROSS NERN MT INTO NRN ND...SUPPRESSING THE UPPER LEVEL HIGH AND FORCING A COLD FRONT THROUGH WESTERN AND NORTH CENTRAL NEBRASKA. FRONTAL TIMING IS FAIRLY CONSISTENT BETWEEN THE NAM/GFS AND ECMWF SOLNS THIS MORNING...AS THE FRONT IS FORECAST TO CLEAR THE AREA BY 00Z TUES. HIGHS MONDAY WILL RANGE FROM THE LOWER 80S IN THE FAR NORTHWEST...TO THE LOWER TO MID 90S IN THE SERN ZONES. AS FOR PCPN CHANCES IN ASSOCIATION WITH THE FRONT...DECIDED TO HOLD OFF ON THE HIGHEST POPS UNTIL MONDAY NIGHT...WHICH IS POST FRONTAL. UPPER LEVEL SUPPORT FOR PRECIPITATION IS DELAYED SOME INTO MONDAY EVENING PER THE LATEST GFS AND ECMWF SOLNS...AND IS ABOUT 6 TO 12 HRS SLOWER THAN THE NAM SOLN WHICH HAS THE BEST SUPPORT ON MONDAY MORNING/AFTERNOON. TUESDAY THROUGH FRIDAY...PRECIPITATION WILL LINGER IN THE SOUTH INTO TUESDAY...AS THE FRONT PUSHES SOUTH INTO KANSAS. HOW FAR THE FRONT TRACKS SOUTH IS STILL UP IN THE AIR AS THE GFS AND ECMWF SOLNS HAVE DIVERGED 180 DEGREES FROM YESTERDAYS RUNS. THE GFS NOW PUSHES THE FRONT WELL SOUTH OF THE AREA...WHILE THE ECMWF FAVORS A MORE NORTHERN SOLN...STALLING THE FRONT ACROSS NRN KS. IN LIGHT OF THE MODEL DIFFERENCES...DECIDED TO KEEP THE EXTENDED FCST CONSISTENT WITH THE PREVIOUS FCST...AND KEEP THINGS DRY WITH HIGHS IN THE 80S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 622 PM CDT FRI SEP 6 2013 THE HRRR SUGGESTS THE TSTM ACTIVITY ACROSS WRN NEB COULD LAST UNTIL 05Z-06Z THIS EVENING. WE SHOULD SEE A VERY SLOW EASTWARD MOTION BETWEEN 5 AND 10 MPH. THIS COULD CAUSE THE ACTIVITY TO MOVE THROUGH KVTN. OTHERWISE VFR IS EXPECTED THROUGH 21Z SATURDAY. THEREAFTER...WE MIGHT SEE MORE ISOLATED STORMS...ALONG A STALLED OUT FRONT...NEAR NEBRASKA HIGHWAY 2 BUT THIS IS UNCERTAIN SINCE ONLY THE ECM SHOWS ANYTHING FORMING AND IT SHOWS A STORM NEAR THE SD BORDER...MUCH FARTHER NORTH. && .FIRE WEATHER... ISSUED AT 334 PM CDT FRI SEP 6 2013 A WEAK COLD FRONT WILL SLIP INTO NORTHERN NEBRASKA SATURDAY. TO THE SOUTH OF THE FRONT...IT WILL AGAIN BE HOT AND DRY WITH HIGHS NEAR 100 AND LOW RELATIVE HUMID TY. WIND AGAIN IS EXPECTED TO BE LIGHT ENOUGH THAT RED FLAG CONDITIONS ARE NOT EXPECTED. SUNDAY COULD BE A DIFFERENT STORY AS TEMPERATURES REMAIN HOT...AND WINDS INCREASE SOME FROM THE SOUTH AND HUMIDITY REMAINS LOW. CONDITIONS SHOULD IMPROVE MONDAY WITH HIGHER HUMIDITY. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...TAYLOR LONG TERM...CLB AVIATION...CDC FIRE WEATHER...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
403 AM CDT THU SEP 5 2013 .SYNOPSIS... ISSUED AT 400 AM CDT THU SEP 5 2013 HUDSON BAY HAS DEEPENED CONSIDERABLY OVER THE PAST 24 HOURS WITH A TROUGH EXTENDING DOWN THE ATLANTIC SEABOARD. HEAT RIDGE CENTERED OVER NORTHEAST COLORADO HOLDS WITH A SHARP RIDGE INTO THE CENTRAL PLAINS OF CANADA. CLOSED LOW OFF THE OREGON COAST NEARLY STATIONARY OVER THE PAST 24 HOURS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 400 AM CDT THU SEP 5 2013 MODELS FAIRLY CONSISTENT IN THE NEAR TERM. RING OF FIRE WITH THE UPPER LOW CENTERED OVER NORTHEAST COLORADO AND WESTERN NEBRASKA POSITIONED FOR WEAK WAVES MOVING THROUGH QUICKLY AND SETTING OFF MAINLY ISOLATED THUNDERSTORMS. WILL CARRY A PRE FIRST PERIOD IN THE ZONES TO ACCOUNT FOR ONGOING PRECIPITATION. ISO T MOVING OUT OF THE FORECAST AREA EARLY THIS MORNING. DEBRIS CLOUDS MAY BE HARD TO GET RID OF TODAY. WITH THIS IN MIND HAVE UNDERCUT GUIDANCE BY A COUPLE OF DEGREES AND KEPT NORTH CENTRAL NEBRASKA COOLER BUT THE SOUTHWEST AND THE EASTERN NEBRASKA PANHANDLE IN THE VICINITY OF THE SURFACE TROUGH WILL SEE TEMPERATURES SOAR TO AROUND 100 DEGREES. STRONG SOUTHEAST FLOW TODAY TO THE EAST OF THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE. WILL SEE ISOLATED THUNDERSTORMS AGAIN IN THE PANHANDLE THIS AFTERNOON AND EVENING BUT SHOULD NOT MAKE IT TOO FAR OFF THE HIGHER TERRAIN AND HAVE ENDED THROUGH THE EVENING. A WARM NIGHT AGAIN WITH LOWS IN THE MID TO UPPER 60S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 400 AM CDT THU SEP 5 2013 HEAT WAVE CONTINUES INTO THE WEEKEND. CENTER OF THE RIDGE WILL DRIFT EAST INTO THE WEEKEND AS TROUGH/LOW COMES ONSHORE ACROSS THE PAC NW. 850 MB TEMPS CONTINUE TO SURGE ABOVE 30 DEGREES ACROSS MOST OF THE AREA DURING THE AFTERNOON BOTH FRIDAY AND SATURDAY. GUIDANCE HAS HIGHS AROUND 100 DEGREES FOR MOST OF THE CWA...AND WILL NOT STRAY FROM GUIDANCE. DISTURBANCES CONTINUES TO ROTATE AROUND THE RIDGE...AND WILL NEED TO KEEP A CHANCE FOR STORMS ACROSS THE NORTHWEST INTO NORTH CENTRAL. LOWER LEVELS ARE FAIRLY DRY HOWEVER MOISTURE ALOFT SHOULD BE ENOUGH TO GET THINGS TO DEVELOP OVER THE HIGHER TERRAIN TO THE WEST THEN DRIFT EAST. QUESTION IS HOWEVER MUCH COVERAGE AND HOW MUCH WILL REACH THE GROUND. WILL CONTINUE SOME ISOLD POPS IN THE FORECAST WITH LOW CONFIDENCE. TROUGH CROSS THE NORTHERN ROCKIES LATE IN THE WEEKEND INTO THE FIRST OF NEXT WEEK. THIS WILL PUSH THE CENTER OF THE RIDGE TO THE SE...WITH 850 MB TEMPS TO BEGIN TO COOL SUNDAY. STILL GOING TO BE TOASTY FOR SEPT...WITH HIGHS IN THE 90S FOR SUNDAY. MONDAY A SURFACE COLD FRONT WILL ENTER THE NW PART OF THE CWA. TIMING IS STILL AN ISSUE WITH MODELS ALTHOUGH SOME IMPROVEMENT FROM THE 12Z RUNS. WILL SEE A CHANCE FOR STORMS AS THE FRONT SLOWLY PUSHES ACROSS THE AREA. TUESDAY WITH CLOUDS AND A CHANCE FOR STORMS...TEMPS CLOSER TO SEASONAL...LOWER TO MID 80S. BY WEDNESDAY COOLER HIGH PRESSURE WILL BUILD ACROSS THE AREA...WITH SHOWERS TO PUSH TO THE SOUTHEAST. HIGHS SHOULD STILL BE ABLE TO WARM INTO THE 80S...AS THE SUN RETURNS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1125 PM CDT WED SEP 4 2013 TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY. OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND 18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z- 00Z. && .FIRE WEATHER... ISSUED AT 400 AM CDT THU SEP 5 2013 MINIMUM RELATIVE HUMIDITIES WILL FALL TO AROUND 20 PERCENT IN THE VICINITY OF THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE THIS AFTERNOON. THIS IS ALSO WHERE WINDS WILL BE THE LIGHTEST. THINGS WILL CONTINUE TO DRY OVER THE NEXT SEVERAL DAYS WITH LITTLE IN THE WAY OF PRECIPITATION. THAT TIME OF YEAR FOR CROPS DRYING. FIRE DANGER WILL INCREASE. && .CLIMATE... ISSUED AT 400 AM CDT THU SEP 5 2013 A RECORD HERE OR THERE MAY FALL OVER THE NEXT FEW DAYS DURING THIS HEAT WAVE...HOWEVER MOST ARE SAFE. OVER THE NEXT 3 DAYS HIGHS WILL APPROACH AND POSSIBLY SURPASS 100 DEGREES ACROSS THE AREA. RECORD HIGHS ARE ALL AT OR ABOVE 100. FOR THE 5TH, 6TH, AND 7TH...MANY OF THE RECORD HIGHS ARE NEAR THE WARMEST OF ALL OF SEPTEMBER...WHICH MAKES IT TOUGHER TO REACH. BELOW ARE THE RECORD HIGHS FOR THE NEXT 3 DAYS. FRIDAY AND SATURDAY ARE THE BEST CHANCE TO SET A RECORD HIGH. LOCATION...RECORD HIGH THURS...FRI...SAT. NORTH PLATTE...105/1931...102/1931...102/1959. VALENTINE......103/1998...101/1980...100/1940. BROKEN BOW.....105/1931...101/1984+...102/1940. IMPERIAL.......110/1931...105/1959+...103/1969. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...POWER SHORT TERM...POWER LONG TERM...MASEK AVIATION...CDC FIRE WEATHER...POWER CLIMATE...MASEK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
113 AM CDT THU SEP 5 2013 .SYNOPSIS... ISSUED AT 342 PM CDT WED SEP 4 2013 UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA. && .UPDATE... ISSUED AT 112 AM CDT THU SEP 5 2013 UPDATING FORECAST TO ACCOUNT FOR ON GOING PRECIPITATION OVER SOUTHWEST NEBRASKA. INCREASED CLOUDS ADJUSTED WINDS AND EXPANDED AREA OF PRECIPITATION. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 342 PM CDT WED SEP 4 2013 THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST. ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES PASSING THROUGH THE FLOW. AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85 T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 342 PM CDT WED SEP 4 2013 FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT 100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH DAKOTA STATE LINE. THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION WILL BE SPOTTY AND FAIRLY LIGHT. IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY. STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT MONDAY THROUGH WEDNESDAY PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1125 PM CDT WED SEP 4 2013 TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY. OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND 18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z- 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...POWER SYNOPSIS...JACOBS SHORT TERM...JACOBS LONG TERM...SPRINGER AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1132 PM CDT WED SEP 4 2013 .SYNOPSIS... ISSUED AT 342 PM CDT WED SEP 4 2013 UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 342 PM CDT WED SEP 4 2013 THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST. ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES PASSING THROUGH THE FLOW. AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85 T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 342 PM CDT WED SEP 4 2013 FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT 100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH DAKOTA STATE LINE. THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION WILL BE SPOTTY AND FAIRLY LIGHT. IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY. STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT MONDAY THROUGH WEDNESDAY PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1125 PM CDT WED SEP 4 2013 TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY. OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND 18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z- 00Z. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JACOBS SHORT TERM...JACOBS LONG TERM...SPRINGER AVIATION...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
950 PM EDT FRI SEP 6 2013 .SYNOPSIS... CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH THE WEEKEND... WHILE WEAKENING. A DRY COLD FRONT WILL MOVE SOUTHWARD THROUGH THE AREA EARLY MONDAY... FOLLOWED BY ANOTHER HIGH PRESSURE AREA PUSHING INTO THE REGION FROM THE NORTH THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 950 PM FRIDAY... THE HIGH PRESSURE WAS CENTERED OVER PA THIS EVENING... AND CONTINUED TO BUILD SOUTHWARD INTO GA/FL. THE FLOW AROUND THE HIGH WAS MOSTLY DRY AT ALL LEVELS EXCEPT BETWEEN H850 TO AROUND H900. THIS MOISTURE SHOWS UP ON THE WALLOPS SOUNDING BEST AND WAS LOCATED IN LINE WITH A MORE ONSHORE FLOW OFF THE ATLANTIC INTO THIS REGION. LOCALLY... SOME CLOUDINESS WAS SPREADING INTO OUR NE ZONES ALREADY... VERY LIMITED IN DEPTH AS WELL. WE WILL CONTINUE THE PARTLY CLOUDY FORECAST NE INTO THE CENTRAL AREAS... AND MOSTLY CLEAR ELSEWHERE. TEMPERATURES ARE IN LINE WITH THE CURRENT FORECAST LOWS IN THE UPPER 50S TO LOWER 60S AS WELL. FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC. -GIH && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 250 PM FRIDAY... FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC. -GIH 1025 MB CONTINENTAL POLAR SURFACE HIGH PRESSURE CENTERED OVER PA/NY THIS AFTERNOON WILL CONTINUE TO MODIFY/WEAKEN...RELATIVELY QUICKLY GIVEN THE STILL RELATIVELY HIGH PRE-EQUINOX SUN ANGLE...AS IT DRIFTS INTO THE SOUTHEASTERN US BY EARLY SUNDAY. MEANWHILE...AN ELONGATED MID-UPPER VORTICITY AXIS AROUND THE NORTHERN PERIPHERY OF A SUB-TROPICAL RIDGE OVER THE ROCKIES...WILL WEAKLY AMPLIFY TOWARD THE BASE OF A STRONGLY POSITIVELY-TILTED LONGWAVE TROUGH AXIS FORECAST TO DEVELOP FROM THE WESTERN ATLANTIC TO THE TX GULF COAST. THE AMPLIFICATION OF THE SHORTWAVE TROUGH AXIS PARENT TO THE VORTICITY CENTERS IN NORTHWESTERLY FLOW ALOFT WILL PROMOTE THE DEVELOPMENT OF A LEE SIDE SURFACE TROUGH OVER THE CAROLINAS ON SUNDAY...BEFORE A REINFORCING COLD FRONT ACCOMPANYING THE SHORTWAVE TROUGH AXIS DRIFTS THROUGH CENTRAL NC SUN NIGHT. AS IT HAS APPEARED FOR DAYS NOW...MOISTURE IN THE NORTHWESTERLY FLOW REGIME...BOTH BOUNDARY AND DEEP LAYER...AND RESULTANT INSTABILITY... ARE EXPECTED TO BE LIMITED. AS SUCH...IT WILL BE DIFFICULT FOR THE ATMOSPHERE TO SUPPORT PRECIPITATION HERE...WITH THE MOST LIKELY SCENARIO BEING A FEW WIDELY SCATTERED REMNANT SHOWERS OR SPRINKLES DRIFTING INTO THE NORTHERN PIEDMONT DURING THE LATE AFTERNOON AND EVENING...AFTER DEVELOPING AND MOVING THROUGH A MORE FAVORABLY UNSTABLE ENVIRONMENT UPSTREAM. OTHER ISOLATED TO WIDELY SCATTERED SEA BREEZE CONVECTION WILL LIKELY REMAIN OVER COASTAL AREAS...OR PERHAPS DRIFT INTO SOUTHERN SAMPSON COUNTY BY SUNSET. THE WARM SECTOR SHOULD BE EFFECTIVELY SHUNTED TO OUR SOUTH...OR TO THE FAR SOUTHERN TIER OF NC BY MON. HOWEVER...THE COMBINATION OF WEAKENING LOW LEVEL FRONTAL FORCING INVOF THE BOUNDARY...AND RESIDUALLY RICH LOW MOISTURE CHARACTERIZED BY UPPER 60S TO NEAR 70 DEGREES SURFACE DEWPOINTS IN POST-FRONTAL ENE LOW LEVEL FLOW... WARRANTS A CONTINUED SLIGHT CHANCE OF SHOWERS AND STORMS MAINLY FROM THE SOUTHERN PIEDMONT TO THE SOUTHERN COASTAL PLAIN. TEMPERATURES SHOULD REBOUND NICELY WITH THE LEE TROUGHING AND BRIEF RESPITE FROM ENE TO NE LOW LEVEL FLOW...WITH TEMPERATURES IN THE 87 TO 92 DEGREE RANGE SUN...THEN 3-5 DEGREES COOLER WITH A BRIEF RETURN OF THE ENE LOW LEVEL FLOW ON MON. PRE- AND POST-FRONTAL PROJECTED LOW LEVEL THICKNESSES SUPPORT LOWS IN THE MIDDLE TO UPPER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 305 PM FRIDAY... A SUB-TROPICAL RIDGE OVER THE CENTRAL PLAINS WILL WEAKEN AND MOVE EASTWARD ACROSS OUR REGION THROUGH MID-WEEK...WHILE THE POSITIVE HEIGHT ANOMALY IN THE MEAN RETROGRADES/RELOADS OVER THE ROCKIES. IN A DEEP LAYER ANTICYCLONIC FLOW...AND ASSOCIATED MID LEVEL WARMTH AND SUBSIDENCE...WILL LIKELY INHIBIT DEEP CONVECTIVE DEVELOPMENT AWAY FROM OROGRAPHIC AND SEA BREEZE FORCING THROUGH MID-WEEK...WITH JUST THE SLIGHTEST OF A CHANCES OF A SHOWER OR STORM DRIFTING INTO THE FAR WESTERN PIEDMONT. THE AFOREMENTIONED RETROGRESSION OF THE RIDGE IN THE MEAN WILL ALLOW A PROGRESSIVE TROUGH ALOFT TO DEVELOP EASTWARD ACROSS THE GREAT LAKES AND EAST COAST LATE WEEK INTO EARLY NEXT WEEKEND. A COLD FRONT WILL ACCOMPANY THE TROUGH...AND THE TIMING OF THIS FEATURE AND NEXT LEGITIMATE CHANCE OF SHOWERS AND STORMS... LOOKS LIKE LATE THU-FRI. CONTINUED WARM...WITH HIGHS MOSTLY IN THE UPPER 80S. LOWS MID-UPPER 60S. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 730 PM FRIDAY... VFR CONDITIONS PREVAIL ACROSS ALL TAF SITES THIS EVENING WITH SOME SCATTERED CLOUDS AROUND 5 KFT...MORE PREVALENT IN THE EAST. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT AS A SURFACE HIGH PRESSURE PARKS OVER THE AREA. THIS COULD LEAD TO SOME VARIABLE WIND DIRECTIONS TOMORROW WITH WESTERN SITES EXPERIENCING LIGHT WINDS OUT OF THE SOUTHWEST AND EASTERN SITES OUT OF THE NORTHEAST. SUFFICE TO SAY THAT WINDS WILL BE LARGELY LIGHT AND VARIABLE THROUGH THE TAF PERIOD REGARDLESS OF WHERE THE HIGH ENDS UP. OVERNIGHT TONIGHT...FORECAST SOUNDINGS AND CROSSOVER TEMPERATURES SUGGEST SOME TEMPORARY LOW STRATUS IN THE NORTHWEST. HRRR SIMULATION OF CEILINGS SHOW LIFR CONDITIONS POSSIBLE AFTER 8Z THROUGH SUNRISE BUT IT MIGHT END UP PRIMARILY WEST OF KINT AND KGSO. WILL LEAVE IN THE TAFS AS A TEMPO GROUP FOR NOW. LONG TERM: PRIMARILY VFR CONDITIONS SHOULD DOMINATE THE REGION THROUGH THE MAJORITY OF THE LONG TERM. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...BADGETT SHORT TERM...MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
731 PM EDT FRI SEP 6 2013 .SYNOPSIS... CANADIAN HIGH PRESSURE WILL DROP ACROSS THE AREA THIS WEEKEND THEN OFFSHORE BY LATE SUNDAY. A WEAK COLD FRONT WILL DISSIPATE OVER THE REGION LATE MONDAY...FOLLOWED BY HIGH PRESSURE THROUGH MID-WEEK. A COLD FRONT IS EXPECTED TO CROSS THE AREA NEXT FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 615 PM FRIDAY...THE FORECASTS HAS BEEN UPDATED A LITTLE EARLY TO ACCOUNT FOR A CLUSTER OF THUNDERSTORMS MOVING SOUTHWESTWARD DOWN THE COAST OF NORTH CAROLINA...NOW APPROACHING SURF CITY. THIS ACTIVITY IS ROOTED WITHIN A NARROW ZONE OF FAIRLY SUBSTANTIAL SURFACE-BASED INSTABILITY (CAPE NEARLY 2000 J/KG) RIGHT ALONG THE COAST WHERE DEWPOINTS HAVE RECOVERED TO 70-72 DEGREES DUE TO THE AFTERNOON SEABREEZE. ON THE WEST (INLAND) SIDE OF THE SEABREEZE WHERE DEWPOINTS ARE 7-10 DEGREES LOWER THERE IS NEGLIGIBLE SURFACE-BASED CAPE AND VIRTUALLY NO CHANCE OF PRECIPITATION THIS EVENING. THE LATEST THREE HRRR RUNS SHOW THERE IS POTENTIAL FOR THIS CONVECTION TO CONTINUE ALL THE WAY DOWN TO SOUTHPORT. 0-6 KM BULK SHEAR IS NEAR 30 KNOTS WHICH IS SUPPORTING THE MULTICELLULAR CHARACTERISTICS WE ARE OBSERVING. PRECIPITABLE WATER ONLY AROUND 1.3 INCHES...KEPT LOW BY ALL THE DRY AIR IN THE MID LEVELS...IS OFFSETTING WHAT COULD BE A SERIOUS FLOODING THREAT GIVEN THE SLOW OBSERVED STORM MOTION. I HAVE INCREASED FORECAST POPS ALONG THE CAPE FEAR COASTLINE THROUGH ABOUT 02Z...WITH CHANCES FOR PRECIPITATION DROPPING BELOW MENTIONABLE THRESHOLDS BY MIDNIGHT EVERYWHERE ON LAND. NO SIGNIFICANT CHANGES HAVE BEEN MADE TO OTHER FORECAST VARIABLES AT THIS TIME. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... ONE ONLY NEEDS TO LOOK AT THE VISIBLE SATELLITE IMAGERY COMBINED WITH SURFACE OBS THIS AFTN TO UNDERSTAND THE SYNOPTIC ENVIRONMENT. TEMPS IN THE UPPER 80S BUT WITH ONLY SCATTERED SHALLOW CU DEVELOPMENT IS A CLEAR INDICATOR OF DRY HIGH PRESSURE BUILDING INTO THE AREA. THIS IS BEHIND A COLD FRONT WHICH HAS SUNK WELL SOUTH OF THE CWA...AND THIS HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE COAST THROUGH TONIGHT. WHILE SURFACE HIGH PRESSURE WILL ACT TO INHIBIT MUCH CONVECTION TODAY...MID-LEVEL SHORTWAVE ROTATING AROUND LONGWAVE TROUGH HAS THE POTENTIAL TO CREATE SOME ISOLATED SHOWERS THIS EVENING AND TONIGHT. HIGH RES GUIDANCE (WRF/HRRR) CONTINUES TO SUGGEST THAT SCATTERED SHOWERS WILL DEVELOP NORTH OF THE LOCAL AREA THIS EVENING AND ADVECT SOUTH INTO THE NORTHERN ZONES TONIGHT. HAVE NOTICED THAT THESE MODELS ARE INITIALIZING "HOT" HOWEVER...AND THE CONVECTION PROGGED TO BE ONGOING AT THE PRESENT TIME HAS NOT MATERIALIZED. STILL...FORECAST SOUNDINGS SUGGEST AMPLE MOISTENING OF THE 1000-800MB LAYER TONIGHT WHICH COMBINED WITH SOME MID-LEVEL FORCING BENEATH THE SHORTWAVE COULD GENERATE A SHOWER OR TWO...CONFINED TO THE NORTHEAST PORTIONS OF THE CWA. HAVE CAPPED POP AT SCHC/ISOLATED...AND SIGNIFICANT DRY AIR ABOVE 700MB WILL INHIBIT CONVECTION FROM BECOMING STRONG...THUS DO NOT EVEN ANTICIPATE LIGHTNING. AT THE VERY LEAST...SOME ENHANCED MID LEVEL CLOUD COVER IS EXPECTED TO DROP SOUTH TO NORTH TONIGHT. MINS TONIGHT WILL BE A LITTLE TRICKY WITH CONTINUED NE WINDS AND THE POTENTIALLY ENHANCED CLOUD COVER...ESPECIALLY IN THE N/NE ZONES. HAVE KEPT MINS SLIGHTLY ABOVE GUIDANCE...SIDING MORE WITH THE WARMER MET NUMBERS...WHICH HAS GENERALLY PERFORMED BETTER THAN THE MAV THIS MONTH. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...MAIN FEATURE OF NOTE SATURDAY AND SUNDAY IS CANADIAN HIGH PRESSURE DROPPING SE ACROSS THE EASTERN CAROLINAS SATURDAY THEN OFFSHORE BY LATE SUNDAY. NE-E WIND FLOW IN THE LOWEST SEVERAL THOUSAND FEET OF THE ATMOSPHERE SATURDAY COULD BRING A MODERATE AMOUNT OF STRATO-CUMULUS SO CERTAINLY DO NOT WANT TO ADVERTISE ALL OUT "SUNNY". SPOTTY LIGHT SHOWERS CANNOT BE RULED OUT ALONG THE NORTH COAST AROUND DAYBREAK SATURDAY BUT WEAK SUBSIDENCE IN WAKE OF AN IMPULSE MOVING SE AND OFFSHORE SHOULD CONFINE SHOWERS SATURDAY OVER THE 0-20 NM COASTAL WATERS AND NORTH TO CAPE LOOKOUT. AS THE HIGH MOVES OFFSHORE LATE ON SUNDAY...A WEAK SHORT-WAVE AND BRIEF SURFACE TROUGH INLAND MAY TRIP OFF A FEW SHOWERS SUNDAY AFTERNOON AND EVENING. AS THIS FEATURE DROPS SOUTH OF THE AREA...THE LEADING EDGE OF CANADIAN HIGH PRESSURE PUSHES A WEAK BACK DOOR FRONT SOUTH INTO OUR NC ZONES. SUBSIDENCE ALOFT APPEARS TO ACCOMPANY THIS FEATURE WITH DRY NORTH FLOW ALOFT AND NO MENTIONABLE POPS PLANNED EARLY MON. SUNDAY MORNING SHOULD BE A FEW DEGREES COOLER THAN SAT MORNING MAINLY BY VIRTUE OF LESS CLOUDS...WITH WIDESPREAD 60S EXPECTED DAYBREAK SUNDAY. MAXIMUMS TEMPS SHOULD BE WARMER ON SUNDAY FOR SIMILAR REASONS OF LESS CLOUD COVER. RETURN FLOW BEGINS LATE SUNDAY EVENING WITH A WEAK WIND SHIFT TO NORTH OVER OUR NC ZONES INTO DAYBREAK MONDAY AS THE CANADIAN HIGH DIPS INTO THE MID-ATLANTIC REGION. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MID LEVEL RIDGING WILL BE THE PREVAILING FEATURE FOR THE FIRST HALF OF THE FORECAST PERIOD. THERE WILL BE SUFFICIENT MOISTURE IN THE COLUMN...PRECIPITABLE WATER VALUES OF 1.80 INCHES... TO MAINTAIN SLIGHT CHANCE POPS MONDAY BEFORE A SURGE OF DRIER AIR MOVES IN FROM THE NORTHEAST. THIS WILL KEEP POPS OUT OF THE PICTURE FOR TUESDAY AND WEDNESDAY. A SIGNIFICANT MID LEVEL TROUGH WILL BRING ANOTHER RELATIVELY STRONG COLD FRONT ACROSS THE AREA FRIDAY. THE SOUTHERLY FLOW AHEAD OF THIS SYSTEM WILL ALLOW SLIGHT CHANCE POPS TO CREEP BACK INTO THE FORECAST THURSDAY WITH THE BETTER FORCING WARRANTING CHANCE VALUES FRIDAY. TEMPERATURE FORECAST LOOKS STABLE WITH VALUES JUST A DEGREE OR TWO ABOVE CLIMATOLOGY THROUGH THE PERIOD. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...CURRENTLY VFR AT ALL TERMS THIS EVENING WITH LIGHT NORTHEAST WINDS. WILL HOLD ONTO VCSH AT KILM EARLY THIS EVENING AS RADAR SHOWS A FEW SHOWERS NEAR THE CAPE FEAR AREA ASSOCIATED WITH AN UPPER SHORTWAVE. DO NOT ANTICIPATE ANY DIRECT IMPACTS TO KILM ATTM. CONTINUED NORTHEAST FLOW OVERNIGHT SHOULD LIMIT THE FOG POTENTIAL FOR OUR CWA. FOG-PRONE KCRE COULD SEE TEMPO MVFR VSBYS BEFORE 06Z IF THE WINDS GO CALM...BUT CONFIDENCE IS FAIRLY LOW. NAM FORECAST SOUNDINGS HINT AT SOME FOG EARLY SATURDAY FOR KFLO/KLBT...BUT THIS SEEMS OVERDONE GIVEN THE BOUNDARY LAYER WINDS AND THE LOWER SFC DEWPOINTS INLAND. THEREFORE...WILL ONLY MENTION LIGHT GROUND FOG AND TEMPO MVFR STRATUS FOR THESE SITES BEFORE 12Z. EXPECT VFR ON SATURDAY AS SFC HIGH PRESSURE RIDGES INTO THE CAROLINAS. THE WINDS WILL BE NORTHEAST IN THE MORNING...BECOMING E-SE AOB 10 KTS IN THE AFTERNOON. EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS IS POSSIBLE SUNDAY THROUGH WEDNESDAY...MAINLY INLAND. SLIGHT CHANCE OF SHOWERS ON MONDAY. OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 615 PM FRIDAY...I HAVE UPDATED THE MARINE FORECAST TO INCREASE THE POTENTIAL OF THUNDERSTORMS THIS EVENING...MAINLY FROM AROUND CAPE FEAR NORTH TO SURF CITY. LATEST NEAR-TERM HIGH RESOLUTION MODELS SHOW THE THUNDERSTORM ACTIVITY APPROACHING SURF CITY MAY MAKE IT DOWN TO SOUTHPORT OVER THE NEXT 2-3 HOURS. AFTER REVIEWING THE LATEST SYNOPTIC MODELS FOR THE OVERNIGHT PERIOD I HAVE INCREASED WIND SPEED FORECASTS BY A FEW KNOTS AFTER MIDNIGHT AND HAVE BACKED WIND DIRECTIONS BY ABOUT 30 DEGREES...MORE NORTHEAST THAN EAST. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... HIGH PRESSURE BUILDING SOUTH FROM THE MID-ATLANTIC WILL CONTINUE TO RIDGE ACROSS THE WATERS TONIGHT...PERSISTING THE NE WINDS PRESENTLY OBSERVED AT THE LOCAL BUOYS. WHILE WINDS HAVE BEEN AROUND 10 KTS MUCH OF THE DAY...A MDT NE SURGE IS STILL PROGGED TONIGHT...DRIVING WINDS UP TO AROUND 15 KTS LATE IN THE PERIOD. THESE WINDS WILL FORCE RISING WAVE HEIGHTS...FROM 1-3 FT...UP TO 3-4 FT LATE TONIGHT WITH A 5 SEC NE WIND CHOP REMAINING DOMINANT WITHIN THE WAVE SPECTRUM. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...MODERATE NE WINDS CAN BE EXPECTED ON THE WATERS SATURDAY AS CANADIAN HIGH PRESSURE DROPS SE TOWARD THE COASTAL WATERS. THIS MAY BRING SEAS TO 4 FEET OVER THE OUTER WATERS AND ALSO NORTH OF CAPE FEAR...BUT NO ADVISORIES OR TSTMS ARE EXPECTED. LIGHT SHOWERS HOWEVER MAY DOT THE WATERS SATURDAY AND MAINLY NORTH OF CAPE FEAR. WINDS WILL EASE AND BECOME LIGHT SATURDAY NIGHT AND SUNDAY AS THE HIGH MOVES NEARLY OVERHEAD OF THE WATERS. AS THE HIGH MOVES OFFSHORE SUNDAY EVENING...EXPECT WINDS TO BECOME S AND SW. HIGHEST WINDS AND SEAS ARE ANTICIPATED SATURDAY WITH OVERALL IMPROVING CONDITIONS LATE SATURDAY AND SUNDAY. LATE SUNDAY NIGHT INTO EARLY MONDAY HIGH PRESSURE DROPPING FROM THE NORTH WILL BRING A WEAK COLD FRONT TO THE NC WATERS. THIS SHOULD BRING A WIND-SHIFT NORTH OF CAPE FEAR BY DAYBREAK MONDAY. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...EASTERLY WINDS INITIALLY WILL BACK TO NORTHEASTERLY LATE MONDAY AND VACILLATE BETWEEN EAST TO NORTHEAST THROUGH WEDNESDAY. THERE MAY BE A LATE SHIFT VERY LATE IN THE PERIOD WEDNESDAY TO SOUTHEAST AS THE PATTERN SHIFTS A BIT BUT THIS WILL NEED TO BE FINE TUNED IN SUBSEQUENT FORECASTS. WIND SPEEDS WILL REMAIN EITHER SIDE OF TEN KNOTS THROUGHOUT THE PERIOD. WAVEWATCH SEAS CONTINUE THE SEEMINGLY SUMMER LONG TREND OF BENIGN SEAS WITH 2-3 FEET PRIMARILY COMPRISED OF SHORTER PERIOD WIND WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...8 NEAR TERM...JDW/TRA SHORT TERM...MJC LONG TERM...SHK AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
730 PM EDT FRI SEP 6 2013 .SYNOPSIS... CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH THE WEEKEND... WHILE WEAKENING. A DRY COLD FRONT WILL MOVE SOUTHWARD THROUGH THE AREA EARLY MONDAY... FOLLOWED BY ANOTHER HIGH PRESSURE AREA PUSHING INTO THE REGION FROM THE NORTH THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 250 PM FRIDAY... THROUGH TONIGHT: CONTINUED QUIET AND DRY... AS SURFACE HIGH PRESSURE SHIFTS TO THE MIDATLANTIC COAST WHILE NOSING SOUTHWARD INTO NC. EARLY IN THE EVENING THE NORTHEASTERLY LOW LEVEL FLOW IS EXPECTED TO DRAW THE LOW LEVEL MOISTURE NOW OVER NE NC AND SE VA TOWARD THE SW... SPREADING INTO EASTERN THEN SOUTHERN NC TONIGHT BEFORE SHIFTING WESTWARD UP AGAINST THE HIGHER TERRAIN LATE TONIGHT. SATELLITE IMAGERY SHOWS A SUBTLE SURFACE BOUNDARY ASSOCIATED WITH THE LEADING EDGE OF THESE CLOUDS... POTENTIALLY RELATED TO A WEAK MID LEVEL WAVE OBSERVED ON WATER VAPOR IMAGERY SWINGING THROUGH THE WEAK EAST COAST TROUGH... AND THIS WILL PROVIDE ANOTHER SMALL SURGE OF MORE STABLE AIR FROM THE NNE INTO NC TONIGHT. THE NAM IS MUCH MORE EMPHATIC THAN THE GFS WITH THIS 925-850 MB MOISTURE... WITH THE FORMER FAVORING A THICK OVERCAST DECK OF CLOUDS WHILE THE LATTER DEPICTS MORE PATCHY CLOUDS. THE EXISTING CLOUDS UPSTREAM ARE NOT OVERCAST... BUT AS THEY SPREAD TO THE SW AND WEST WHILE MIXING WANES AND THE LOW LEVELS STABILIZE... WE COULD SEE THE HOLES IN THE CLOUD COVER FILL IN AS THIS MOISTURE BECOMES TRAPPED BENEATH A LARGER SUBSIDENCE INVERSION ALOFT WITH WEAK HORIZONTAL DISPERSION AS WINDS BECOME EVEN LIGHTER. WILL SPREAD PARTLY CLOUDY SKIES OVER THE EASTERN THEN SRN AND WRN CWA THROUGH THE NIGHT. TEMPS ARE TOUGH SINCE THEY WILL DEPEND ON HOW MUCH CLOUD COVERAGE THERE IS OVERNIGHT TO HAMPER RADIATIONAL COOLING. GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH UPPER 50S FAR NORTH AND WEST TRENDING TO LOW 60S SOUTHEAST... SO WILL HOLD CLOSE TO THESE NUMBERS. FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC. -GIH && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 250 PM FRIDAY... 1025 MB CONTINENTAL POLAR SURFACE HIGH PRESSURE CENTERED OVER PA/NY THIS AFTERNOON WILL CONTINUE TO MODIFY/WEAKEN...RELATIVELY QUICKLY GIVEN THE STILL RELATIVELY HIGH PRE-EQUINOX SUN ANGLE...AS IT DRIFTS INTO THE SOUTHEASTERN US BY EARLY SUNDAY. MEANWHILE...AN ELONGATED MID-UPPER VORTICITY AXIS AROUND THE NORTHERN PERIPHERY OF A SUB-TROPICAL RIDGE OVER THE ROCKIES...WILL WEAKLY AMPLIFY TOWARD THE BASE OF A STRONGLY POSITIVELY-TILTED LONGWAVE TROUGH AXIS FORECAST TO DEVELOP FROM THE WESTERN ATLANTIC TO THE TX GULF COAST. THE AMPLIFICATION OF THE SHORTWAVE TROUGH AXIS PARENT TO THE VORTICITY CENTERS IN NORTHWESTERLY FLOW ALOFT WILL PROMOTE THE DEVELOPMENT OF A LEE SIDE SURFACE TROUGH OVER THE CAROLINAS ON SUNDAY...BEFORE A REINFORCING COLD FRONT ACCOMPANYING THE SHORTWAVE TROUGH AXIS DRIFTS THROUGH CENTRAL NC SUN NIGHT. AS IT HAS APPEARED FOR DAYS NOW...MOISTURE IN THE NORTHWESTERLY FLOW REGIME...BOTH BOUNDARY AND DEEP LAYER...AND RESULTANT INSTABILITY... ARE EXPECTED TO BE LIMITED. AS SUCH...IT WILL BE DIFFICULT FOR THE ATMOSPHERE TO SUPPORT PRECIPITATION HERE...WITH THE MOST LIKELY SCENARIO BEING A FEW WIDELY SCATTERED REMNANT SHOWERS OR SPRINKLES DRIFTING INTO THE NORTHERN PIEDMONT DURING THE LATE AFTERNOON AND EVENING...AFTER DEVELOPING AND MOVING THROUGH A MORE FAVORABLY UNSTABLE ENVIRONMENT UPSTREAM. OTHER ISOLATED TO WIDELY SCATTERED SEA BREEZE CONVECTION WILL LIKELY REMAIN OVER COASTAL AREAS...OR PERHAPS DRIFT INTO SOUTHERN SAMPSON COUNTY BY SUNSET. THE WARM SECTOR SHOULD BE EFFECTIVELY SHUNTED TO OUR SOUTH...OR TO THE FAR SOUTHERN TIER OF NC BY MON. HOWEVER...THE COMBINATION OF WEAKENING LOW LEVEL FRONTAL FORCING INVOF THE BOUNDARY...AND RESIDUALLY RICH LOW MOISTURE CHARACTERIZED BY UPPER 60S TO NEAR 70 DEGREES SURFACE DEWPOINTS IN POST-FRONTAL ENE LOW LEVEL FLOW... WARRANTS A CONTINUED SLIGHT CHANCE OF SHOWERS AND STORMS MAINLY FROM THE SOUTHERN PIEDMONT TO THE SOUTHERN COASTAL PLAIN. TEMPERATURES SHOULD REBOUND NICELY WITH THE LEE TROUGHING AND BRIEF RESPITE FROM ENE TO NE LOW LEVEL FLOW...WITH TEMPERATURES IN THE 87 TO 92 DEGREE RANGE SUN...THEN 3-5 DEGREES COOLER WITH A BRIEF RETURN OF THE ENE LOW LEVEL FLOW ON MON. PRE- AND POST-FRONTAL PROJECTED LOW LEVEL THICKNESSES SUPPORT LOWS IN THE MIDDLE TO UPPER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 305 PM FRIDAY... A SUB-TROPICAL RIDGE OVER THE CENTRAL PLAINS WILL WEAKEN AND MOVE EASTWARD ACROSS OUR REGION THROUGH MID-WEEK...WHILE THE POSITIVE HEIGHT ANOMALY IN THE MEAN RETROGRADES/RELOADS OVER THE ROCKIES. IN A DEEP LAYER ANTICYCLONIC FLOW...AND ASSOCIATED MID LEVEL WARMTH AND SUBSIDENCE...WILL LIKELY INHIBIT DEEP CONVECTIVE DEVELOPMENT AWAY FROM OROGRAPHIC AND SEA BREEZE FORCING THROUGH MID-WEEK...WITH JUST THE SLIGHTEST OF A CHANCES OF A SHOWER OR STORM DRIFTING INTO THE FAR WESTERN PIEDMONT. THE AFOREMENTIONED RETROGRESSION OF THE RIDGE IN THE MEAN WILL ALLOW A PROGRESSIVE TROUGH ALOFT TO DEVELOP EASTWARD ACROSS THE GREAT LAKES AND EAST COAST LATE WEEK INTO EARLY NEXT WEEKEND. A COLD FRONT WILL ACCOMPANY THE TROUGH...AND THE TIMING OF THIS FEATURE AND NEXT LEGITIMATE CHANCE OF SHOWERS AND STORMS... LOOKS LIKE LATE THU-FRI. CONTINUED WARM...WITH HIGHS MOSTLY IN THE UPPER 80S. LOWS MID-UPPER 60S. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 730 PM FRIDAY... VFR CONDITIONS PREVAIL ACROSS ALL TAF SITES THIS EVENING WITH SOME SCATTERED CLOUDS AROUND 5 KFT...MORE PREVALENT IN THE EAST. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT AS A SURFACE HIGH PRESSURE PARKS OVER THE AREA. THIS COULD LEAD TO SOME VARIABLE WIND DIRECTIONS TOMORROW WITH WESTERN SITES EXPERIENCING LIGHT WINDS OUT OF THE SOUTHWEST AND EASTERN SITES OUT OF THE NORTHEAST. SUFFICE TO SAY THAT WINDS WILL BE LARGELY LIGHT AND VARIABLE THROUGH THE TAF PERIOD REGARDLESS OF WHERE THE HIGH ENDS UP. OVERNIGHT TONIGHT...FORECAST SOUNDINGS AND CROSSOVER TEMPERATURES SUGGEST SOME TEMPORARY LOW STRATUS IN THE NORTHWEST. HRRR SIMULATION OF CEILINGS SHOW LIFR CONDITIONS POSSIBLE AFTER 8Z THROUGH SUNRISE BUT IT MIGHT END UP PRIMARILY WEST OF KINT AND KGSO. WILL LEAVE IN THE TAFS AS A TEMPO GROUP FOR NOW. LONG TERM: PRIMARILY VFR CONDITIONS SHOULD DOMINATE THE REGION THROUGH THE MAJORITY OF THE LONG TERM. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
130 PM EDT THU SEP 5 2013 .SYNOPSIS... A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT. CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH GRADUAL WEAKENING THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM THURSDAY... A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST 1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS. HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON. THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE.. SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90. ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH. LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S SOUTH. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 215 AM THURSDAY... CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S TO NEAR 80 NORTH TO MID 80S SOUTH. THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 245 AM THURSDAY... OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION. THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK. HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE. FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY BELOW NORMAL TEMPS ARE EXPECTED. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 130 PM THURSDAY... VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. MOISTURE ALONG AND EAST OF A STALLED FRONT OVER THE COASTAL PLAIN IS LEADING TO A SCATTERED CU FIELD WITH BASES AT 5K FT OR HIGHER TO THE SOUTH AND EAST KRDU. THIS EVENING...A DRY COLD FRONT WILL PUSH SOUTH THROUGH THE AREA...BETWEEN ROUGHLY 03-07Z...WITH WINDS TURNING TO NORTHEASTERLY AND POSSIBLY GUSTING TO 15-20KT IMMEDIATELY BEHIND THE FRONT. WINDS WILL REMAIN OUT OF THE NORTHEAST ON FRIDAY. OUTLOOK... OUTSIDE OF POCKETS OF SUB-VFR VSBYS IN THE EARLY MORNING HOURS...VFR CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. A COLD FRONT WILL PUSH SOUTH INTO THE AREA BY MONDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/SMITH SHORT TERM...CBL LONG TERM...KRR AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1015 AM EDT THU SEP 5 2013 .SYNOPSIS... A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT. CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH GRADUAL WEAKENING THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM THURSDAY... A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST 1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS. HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON. THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE.. SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90. ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH. LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S SOUTH. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 215 AM THURSDAY... CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S TO NEAR 80 NORTH TO MID 80S SOUTH. THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 245 AM THURSDAY... OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION. THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK. HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE. FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY BELOW NORMAL TEMPS ARE EXPECTED. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 720 AM THURSDAY... 24 HOUR TAF PERIOD: CLEAR SKIES AND CALM WINDS WILL SUPPORT AREAS OF FOG OVERNIGHT...ESPECIALLY ACROSS CENTRAL AND EASTERN PORTIONS OF THE STATE WHERE LOW-LEVEL REMAINS HIGH IN CLOSER PROXIMITY TO A DISSIPATING STALLED SURFACE FRONT. AFTER DAYBREAK...EXPECT CONDITIONS TO IMPROVE BACK TO VFR (BY APPROX 12-13Z) FOR THE REMAINDER OF THE TAF PERIOD WITH LIGHT NORTH-NORTHWESTERLY WINDS THROUGHOUT THE DAY. A SECONDARY DRY COLD FRONT WILL PUSH SOUTH THROUGH THE AREA BETWEEN 00 TO 09Z FRIDAY. COULD SEE A BRIEF 1-2HR PERIOD OF NELY WIND GUSTS IMMEDIATELY BEHIND THE FRONT...OTHERWISE NO SIGNIFICANT WEATHER IS EXPECTED. LOOKING AHEAD: ASIDE FROM SOME EARLY MORNING FOG..A DRY BELOW NORMAL PWAT AIRMASS WITH HIGH PRES AT THE SURFACE WILL RESULT IN PREDOMINATELY VFR CONDITIONS THROUGH THE WEEKEND. ANOTHER DRY BACK-DOOR COLD FRONTAL WILL PUSH SOUTH THROUGH THE AREA SUNDAY NIGHT AND INTO EARLY MONDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/SMITH SHORT TERM...CBL LONG TERM...KRR AVIATION...CBL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
134 PM CDT THU SEP 5 2013 .UPDATE... ISSUED AT 1247 PM CDT THU SEP 5 2013 EARLY AFTERNOON UPDATE FOR MIDDAY TEMPERATURE AND SKY COVER TRENDS...OTHERWISE CURRENT FORECAST IS ON TRACK. THE MAIN FORECAST ISSUE FOR TONIGHT THROUGH FRIDAY NIGHT IS THE POTENTIAL FOR ANOTHER ROUND OF THUNDERSTORM ACTIVITY AND THE ASSOCIATED THREAT FOR ISOLATED SEVERE WEATHER. IN THE NEAR TERM...OPTED FOR A DRY FORECAST TONIGHT WITH LITTLE IN THE WAY OF FORCING EXPECTED. ON FRIDAY...INSTABILITY AND MOISTURE WILL BE ON THE INCREASE. A SURFACE TROUGH IS EXPECTED TO STRETCH ACROSS WESTERN ND AND SYNOPTIC SCALE FORCING SHOULD BE ON THE INCREASE DURING THE LATE AFTERNOON/EVENING HOURS AS SHORT WAVE ENERGY RIDES UP THE UPPER RIDGE. THE ENTIRE FORECAST AREA IS IN THE 5 PERCENT RISK AREA FOR ISOLATED SEVERE STORMS. HAVE SPEEDED UP THE TIMING OF THE AFTERNOON POPS IN A NOD TO THE FASTER SOLUTIONS...AND MODEL CONSENSUS SUPPORTS AN INCREASE IN POPS FOR FRIDAY NIGHT...ESPECIALLY WEST. A LIMITING FACTOR FOR SEVERE WEATHER WILL BE RELATIVELY MODEST DEEP LAYER SHEAR...BUT UNDOUBTEDLY THERE WILL BE AT LEAST A FEW STORMS TO MONITOR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS PRECIPITATION CHANCES. RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE. CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA. WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER 90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S. DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES SHOULD REMAIN IN THE 90S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST. EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING. AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT. GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS POSSIBILITY IN THE HWO. THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO. FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1017 AM CDT THU SEP 5 2013 EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A LIGHT SOUTHEAST WIND UNDER 10 KTS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE/AVIATION...RP KINNEY SHORT TERM...LTH LONG TERM...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1031 AM CDT THU SEP 5 2013 .UPDATE... ISSUED AT 1017 AM CDT THU SEP 5 2013 UPDATE TO REMOVE POPS ACROSS THE WEST FOR THE LATE MORNING AS THE ISOLATED THUNDERSTORMS HAVE DISSIPATED. OTHERWISE...EXPECT A MOSTLY SUNNY SKY TODAY WITH QUIET WEATHER. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS PRECIPITATION CHANCES. RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE. CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA. WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER 90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S. DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES SHOULD REMAIN IN THE 90S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST. EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING. AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT. GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS POSSIBILITY IN THE HWO. THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO. FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1017 AM CDT THU SEP 5 2013 EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A LIGHT SOUTHEAST WIND UNDER 10 KTS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE/AVIATION...RP KINNEY SHORT TERM...LTH LONG TERM...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT THU SEP 5 2013 .UPDATE... ISSUED AT 636 AM CDT THU SEP 5 2013 ONGOING CONVECTION OVER EASTERN MONTANA IS DISORGANIZED AND VERY SLOW MOVING. IT MAY NOT EVEN HOLD TOGETHER TO MAKE IT TO THE MT/ND BORDER. NEVERTHELESS...MAINTAINED SLIGHT CHANCE POPS WEST THIS MORNING. A DRYING TREND IS STILL EXPECTED THIS AFTERNOON AS AN UPPER WAVE MOVES EAST OF THE CWA. OTHERWISE...NO MAJOR CHANGES WERE REQUIRED TO THE ONGOING FORECAST. ADJUSTED THE HOURLY TEMP/WIND/DEWPOINT GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS PRECIPITATION CHANCES. RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE. CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA. WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER 90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S. DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES SHOULD REMAIN IN THE 90S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST. EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING. AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT. GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS POSSIBILITY IN THE HWO. THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO. FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 636 AM CDT THU SEP 5 2013 VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 12Z TAF PERIOD. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN NORTH DAKOTA DURING THE EARLY MORNING HOURS. HOWEVER...UNCERTAINTY REMAINS TOO GREAT TO INCLUDE ANY PREVAILING THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO HAVE INCLUDED VCSH TO KDIK AND KISN TO INDICATE POSSIBLE TIMING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...LTH LONG TERM...TM AVIATION...LTH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 AM CDT THU SEP 5 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS PRECIPITATION CHANCES. RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE. CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA. WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER 90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S. DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES SHOULD REMAIN IN THE 90S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 349 AM CDT THU SEP 5 2013 THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST. EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING. AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT. GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS POSSIBILITY IN THE HWO. THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO. FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 106 AM CDT THU SEP 5 2013 VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 06Z TAF PERIOD. SCATTERED SHOWERS CURRENTLY OVER THE NORTH CENTRAL PART OF THE STATE WILL CONTINUE TO MOVE EAST. ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN NORTH DAKOTA OVER THE NEXT FEW HOURS. HOWEVER...UNCERTAINTY REMAINS TOO GREAT TO INCLUDE ANY PREVAILING THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO HAVE INCLUDED VCSH TO KDIK...KMOT...AND KBIS TO INDICATE POSSIBLE TIMING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LTH LONG TERM...TM AVIATION...LTH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
641 AM EDT THU SEP 5 2013 .SYNOPSIS... A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH CLOUDS...SKIES SHOULD BE MOSTLY CLEAR. THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO- SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND MID 70S IN THE NE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH UPPER 40S EXPECTED IN OUTLYING AREAS. THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET. ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON (GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB). HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN CURRENTLY ANTICIPATED. A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP MENTION OF SHOWERS OUT OF THE FORECAST. UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED PERIOD. HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... A MOISTURE STARVED COLD FRONT WILL DROP SOUTH THROUGH THE TAF SITES THIS MORNING. ANY MIST/FOG EARLY THIS MORNING SHOULD BE GONE BETWEEN 13Z AND 14Z DUE TO MIXING AND/OR A WIND SHIFT TO THE NORTH. FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER. SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN SCT-BKN CUMULUS CLOUDS. FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION. SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST... ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA. SOME SHALLOW GROUND FOG MAY BE POSSIBLE AT KILN AND RIVER FOG AT KLUK LATE TONIGHT. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
400 AM EDT THU SEP 5 2013 .SYNOPSIS... A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH CLOUDS...SKIES SHOULD BE MOSTLY CLEAR. THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO- SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND MID 70S IN THE NE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH UPPER 40S EXPECTED IN OUTLYING AREAS. THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET. ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON (GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB). HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN CURRENTLY ANTICIPATED. A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP MENTION OF SHOWERS OUT OF THE FORECAST. UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED PERIOD. HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... A MOISTURE STARVED COLD FRONT WILL DROP SOUTH FROM THE SOUTHERN GREAT LAKES TO THE OHIO RIVER VALLEY BY MORNING. AHEAD OF THE FRONT...ENOUGH LOW LEVEL MOISTURE AND MAINLY CLEAR SKIES/LIGHT WINDS MAY ALLOW FOR SOME MVFR MIST TO FORM AT KILN AND KLUK WITH PERHAPS A PERIOD OF IFR VSBYS AT KLUK BEFORE FRONTAL PASSAGE. OTHERWISE...THE FRONT WILL BE MARKED BY A WIND SHIFT TO THE NORTH ALONG WITH A FEW-SCT STRATOCUMULUS CLOUDS NEAR THE NORTHERN TAF SITES. FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER. SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN SCT-BKN CUMULUS CLOUDS. FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION. SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST... ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
211 PM PDT THU SEP 5 2013 .SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS AND THUNDERSTORMS TONIGHT. LOCALIZED HEAVY RAINFALL IS EXPECTED THROUGH FRIDAY MORNING AS THE LOW MOVES OVER THE AREA.SHOWERS WILL DECREASE FRIDAY EVENING TO THE SOUTH BUT LINGER ACROSS THE NORTH THROUGH SATURDAY MORNING. HIGH PRESSURE WILL BUILD BEHIND THE LOW WITH DRIER WEATHER EXPECTED BY SUNDAY. WARMER WEATHER IS EXPECTED EARLY NEXT WEEK. && .SHORT TERM....CONVECTIVE BANDS CIRCULATING AROUND AN UPPER LOW ARE MOVING OVER LANE COUNTY EARLY THIS AFTERNOON...WITH THUNDERSTORMS PRODUCING ABUNDANT LIGHTNING AND HEAVY RAIN. WE HAVE RECEIVED REPORTS OF POWER OUTAGES...LOCALIZED PONDING OF WATER ON ROADWAYS WITH THESE STORMS SO FAR...AS WELL AS ONE REPORT OF SMALL HAIL. THE LOW CENTER IS CURRENTLY AROUND 60 MILES OFF OF THE SOUTHERN OREGON COAST AND WILL BE PUSHING INLAND ACROSS NW OREGON THIS AFTERNOON AND EVENING. AS IT MOVES INLAND SHOWERS AND THUNDERSTORMS WILL SHIFT NORTHWARD. THE HRRR MODELED COMPOSITE REFLECTIVITIES HAS BEEN DOING A GREAT JOB OF FORECASTING THE LOCATION OF RAIN THIS MORNING AND SHOWS THE MAIN RAIN BAND WILL BE CENTERED OVER THE CENTRAL WILLAMETTE VALLEY BY 4PM THIS EVENING AND CENTERED OVER THE PORTLAND METRO AREA BY 7 PM. THIS BAND SEEMS TO THIN AND FALL APART AS IT MOVES NORTH...AND EXPECT THUNDERSTORM COVERAGE TO LESSEN. HOWEVER...SHOWERS WRAPPING AROUND THE LOW WILL EXPAND OVER THE AREA LATER TONIGHT AS THE LOW MOVES FURTHER TO THE NE...AND LOCALIZED HEAVY RAIN WILL CONTINUE THROUGH THE NIGHT. WRAP AROUND SHOWERS WILL CONTINUE FRIDAY AS THE LOW SHIFTS NE OF THE AREA...MAINLY NORTH OF SALEM. THE MODELS HAVE SLOWED THE TIMING OF THE RIDGE BUILDING OVER THE AREA AND DELAYING DRYING OVER THE AREA. SOUTHERN AREAS WILL DRY SATURDAY...BUT SHOWERS MAY LINGER ACROSS THE SOUTHERN WASHINGTON THROUGH SATURDAY MORNING. .LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT...A STRONG LATE SEASON RIDGE WILL BUILD INTO THE PAC NW SUNDAY THROUGH TUESDAY HOLD THROUGH LATE NEXT WEEK. THE LATEST MEDIUM RANGE MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW. THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A SIGNIFICANT WARM UP NEXT WEEK. THE OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR WARMEST TEMPERATURES OF THE SEASON. && .AVIATION...CONVECTIVE ACTIVITY HAS PICKED UP THIS AFTERNOON AND WILL CONTINUE TO BRING HEAVY RAIN...LIGHTNING...AND OCCASIONAL GUSTY WINDS TO TAF SITES AS LOW PRES PUSHES INLAND. MUCH OF THE ACTIVITY HAS MAINLY BEEN SOUTH OF SALEM...BUT SHOWERS WILL CONTINUE TO LIFT NORTH OVERNIGHT. EXPECT MOSTLY MVFR CIGS THROUGH TONIGHT. KPDX AND APPROACHES...EXPECT SHOWERS TO INCREASE THROUGH 00Z THIS AFTERNOON AND CONTINUE INTO FRIDAY MORNING. MVFR CIGS WILL CONTINUE...WITH VIS DROPPING TO MVFR IN HEAVIER SHOWERS ESPECIALLY OVERNIGHT. /27 && .MARINE...AN UPPER LOW WILL MOVE SOUTH OF THE COASTAL WATERS THIS AFTERNOON AND MOVE ONSHORE TONIGHT AND EARLY FRIDAY. OVERALL BENIGN WIND AND SEA CONDITIONS WILL PERSIST THROUGH EARLY SATURDAY AS THE SYSTEM PUSHES FURTHER INLAND. HIGH PRESSURE OVER THE NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4 TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /27/NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WA...NONE. PZ...NONE. && $$ MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
1110 PM PDT WED SEP 4 2013 .SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA. SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK. && ,MESOSCALE UPDATE...SHOWERS AND TSTORMS HAVE INCREASED IN RESPONSE TO THE UPPER SHORTWAVE OFF THE COAST IN AN AREA OF UPPER LEVEL DIVERGENCE/LIFT ON THE LEFT EXIT OF A STRONG HIGH LEVEL JET. EXPECT THESE TO CONTINUE TO SPREAD NORTH. LATEST HRRR STILL SUGGESTING THIS MAIN BAND WILL HEAD NORTHWEST TOWARD THE NORTH OREGON COAST RANGE/COAST...THOUGH ADDITIONAL ACTIVITY IS POSSIBLE FURTHER EAST TOWARD THE PORTLAND/VANCOUVER METRO AREAS...AS A FEW CELLS HAVE BEEN POPPING UP OUTSIDE THE MAIN BAND. KMD .EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT. FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY MORNING. OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH. UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN. GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT THIS POINT IN TIME. /NEUMAN .LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY... AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW. THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR WARMEST TEMPERATURES OF THE SEASON. && .AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING. KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN && .MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4 TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WA...NONE. PZ...NONE. && $$ MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
905 PM PDT WED SEP 4 2013 .SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA. SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK. && .EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT. FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY MORNING. OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH. UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN. GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT THIS POINT IN TIME. /NEUMAN .LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY... AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW. THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR WARMEST TEMPERATURES OF THE SEASON. && .AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING. KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN && .MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4 TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WA...NONE. PZ...NONE. && $$ MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1134 PM EDT FRI SEP 6 2013 .SYNOPSIS... HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY. A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY... FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK. TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING HUMIDITY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS RUNNING IN THE M40S ACROSS MOST OF THE REGION. THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY TO MOSTLY SUNNY SKIES. A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS. HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR 80F THROUGHOUT THE LOWER SUSQ VALLEY. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/ DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT. DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING THE MORNING. ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY INT HE 40S ELSEWHERE. MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST. A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE US. TEMPS WILL AGAIN MOVE ABOVE NORMAL. THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE CFRONT. DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY SKIES SHOULD PREVAIL ELSEWHERE. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... NO CHANGES MADE TO 03Z TAFS. EARLIER DISCUSSION BELOW. OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO PREVAIL INTO SAT. ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE COLD FRONT AND UPSLOPE FLOW. A RETURN TO DRY CONDITIONS FOR MONDAY. VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME SHOULD BE DRY WITH VFR CONDITIONS. OUTLOOK... SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA. MON...VFR. NO SIG WX. TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1034 PM EDT FRI SEP 6 2013 .SYNOPSIS... HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY. A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY... FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK. TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING HUMIDITY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS RUNNING IN THE M40S ACROSS MOST OF THE REGION. THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY TO MOSTLY SUNNY SKIES. A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS. HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR 80F THROUGHOUT THE LOWER SUSQ VALLEY. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/ DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT. DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING THE MORNING. ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY INT HE 40S ELSEWHERE. MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST. A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE US. TEMPS WILL AGAIN MOVE ABOVE NORMAL. THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE CFRONT. DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY SKIES SHOULD PREVAIL ELSEWHERE. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO PREVAIL INTO SAT. ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE COLD FRONT AND UPSLOPE FLOW. A RETURN TO DRY CONDITIONS FOR MONDAY. VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME SHOULD BE DRY WITH VFR CONDITIONS. OUTLOOK... SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA. MON...VFR. NO SIG WX. TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
931 PM EDT FRI SEP 6 2013 .SYNOPSIS... HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY. A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY... FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK. TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING HUMIDITY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE TOWARD PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF THE STATE. HAVE THEREFORE RAISED OVERNIGHT MIN TEMPS A BIT ACROSS THE NW MTNS. THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE TOWARD DAWN IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF THE REGION...WITH LOWS IN THE M40S MOST SPOTS...SO ANY FOG SHOULD BE ISOLATED. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY TO MOSTLY SUNNY SKIES. A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS. HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR 80F THROUGHOUT THE LOWER SUSQ VALLEY. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/ DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT. DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING THE MORNING. ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY INT HE 40S ELSEWHERE. MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST. A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE US. TEMPS WILL AGAIN MOVE ABOVE NORMAL. THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE CFRONT. DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY SKIES SHOULD PREVAIL ELSEWHERE. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO PREVAIL INTO SAT. ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE COLD FRONT AND UPSLOPE FLOW. A RETURN TO DRY CONDITIONS FOR MONDAY. VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME SHOULD BE DRY WITH VFR CONDITIONS. OUTLOOK... SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA. MON...VFR. NO SIG WX. TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
816 PM EDT FRI SEP 6 2013 .SYNOPSIS... HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY. A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY... FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK. TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING HUMIDITY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE TOWARD PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF THE STATE. HAVE THEREFORE RAISED OVERNIGHT MIN TEMPS A BIT ACROSS THE NW MTNS. THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE TOWARD DAWN IN THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF THE REGION...WITH LOWS IN THE M40S MOST SPOTS...SO ANY FOG SHOULD BE ISOLATED. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY TO MOSTLY SUNNY SKIES. A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS. HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR 80F THROUGHOUT THE LOWER SUSQ VALLEY. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/ DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT. DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING THE MORNING. ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY INT HE 40S ELSEWHERE. MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST. A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE US. TEMPS WILL AGAIN MOVE ABOVE NORMAL. THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE CFRONT. DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY SKIES SHOULD PREVAIL ELSEWHERE. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... CLEAR SKIES AND LIGHT WINDS WILL PREVAIL OVERNIGHT. EARLIER DISCUSSION BELOW. VFR FLYING WILL BE THE RULE THROUGH SATURDAY WITH CLR SKIES AND LGT WINDS...AS SFC HIGH PRESSURE DRIFTS SEWD FROM WRN PA TO THE NC/VA COAST. SOME FOG IS POSSIBLE AROUND DAYBREAK ESPECIALLY NEAR BODIES OF WATER...RIVER-STREAM VALLEYS...BUT THE DRY CANADIAN AIRMASS SHOULD LIMIT VSBY RESTRICTIONS. A COLD FRONT WILL PUSH SWD FROM THE LWR GRT LKS THRU THE AIRSPACE ON SUNDAY. THE FRONT SHOULD BE PRECEDED BY SCT LGT SHOWERS...FOLLOWED BY A WSW-NNW SFC WIND SHIFT AND A BAND OF LOWER END VFR TO MVFR CIGS. HIGH PRES RETURNS ON MONDAY WITH VFR PREVAILING INTO TUES. SOME AM FOG IS POSSIBLE TUESDAY MORNING AS LLVL MSTR GRADUALLY INCREASES WIND SFC WINDS BCMG S-SW. THE INCREASE IN MSTR/HUMIDITY MAY SUPPORT ISOLD CONVECTION TUES AFTN-EVE OVR WRN PA/ZOB SECTOR. OUTLOOK... SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA. MON...VFR. NO SIG WX. TUE/WED...AM FOG PSBL. VFR WITH ISOLD PM TSTM IMPACTS PSBL WEST. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...DEVOIR/LA CORTE/MARTIN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1226 PM CDT THU SEP 5 2013 .DISCUSSION... See aviation discussion below... && .AVIATION... Isolated showers will develop across the southern half of West Central Texas this afternoon. I have included a VCTS mention at KJCT, KSOA, and KBBD, ending shortly after sunrise. For now I have left a mention of thunder out of the KABI and KSJT TAF, but I will continue to monitor. Otherwise, expect light winds and VFR conditions through the next 24 hours. && .PREV DISCUSSION... /ISSUED 1144 AM CDT THU SEP 5 2013/ UPDATE... To expand POPS north... DISCUSSION... I sent out a quick update to expand isolated POPS north into the Heartland and Concho Valley this afternoon. A cumulus field is beginning to develop across the region, with low level moisture higher than originally anticipated. High resolution models including the Texas Tech WRF and HRRR are indicating isolated showers and thunderstorms developing this afternoon across the southern half of West Central Texas. For this reason, I have expanded POPS north as previously mentioned. I have also tweaked temperatures down a degree or two across much of the region, given the expected higher dewpoints and increased cloud cover...with the hottest temperatures across the Big Country. Otherwise, no other changes are needed at this time. PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/ DISCUSSION... Please see aviation section below for discussion. AVIATION... Look for beautiful flight weather to continue across West Central Texas for the next 24 hours. High pressure will continue to dominate; thus, I`m expecting light surface winds around 6 knots or less for another 24 hours. Huber PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/ SHORT TERM... (today and tonight) Thunderstorms may develop across our Northern Edwards Plateau and Northwest Hill Country counties this afternoon and evening. Otherwise, expect hot and dry conditions to continue for at least another 24 hours. High pressure will remain dominate over the southern Plains for the next 24 hours. Our southern counties will remain just outside the major influence of this high and its associated subsidence. Thus, I`ve decided to continue slight chance POPs across our southern counties, as this area has been an area of convective development during the last couple afternoons. As for temperatures, I`m going with highs today just above the adjusted MEX model data, simply because that`s been the trend the last couple days, with highs just above model guidance. Lows tonight close to persistence look reasonable. Huber LONG TERM... (Friday through Wednesday) The main forecast items of interest in the long term include possible low rain chances in the southern part of our forecast area, and a slow decrease in maximum temperatures over the course of several days. Friday through the weekend, the upper high will slowly weaken as it shifts east across Kansas. Our area will continue to be on the southern periphery of this upper high. The 00Z GFS and NAM are less favorable with QPF across our southern counties on Friday. However, given what has occurred during the past couple of days, plan to continue with low POPs in our southern counties for isolated afternoon and evening showers/thunderstorms across that area, where sufficient moisture should remain. On the fence whether to carry an isolated mention for afternoon/ early evening showers and thunderstorms this weekend across roughly the southern third of West Central Texas. The 00Z models have trended down a bit with mid-level moisture, and mid/upper forcing will be weak. Planning to leave out the mention for now. Early next week the upper level high is progged to shift into the southeastern part of the country, with an upper trough moving east across the northern Plains and into southwestern Ontario Province in Canada. Over our area, the flow aloft will transition to southeasterly through a deeper layer, but with the latest model indications this may be short-lived. The 00Z GFS and ECMWF show more ridging aloft over the northern half of Texas by the middle of next week. With uncertainty in the specifics of how the upper level pattern will evolve next week, holding off with any mentionable rain chance in our counties at this time. With a slight decrease in 850 mb temperatures across our area along with some increase in cloud cover, maximum temperatures are expected to decrease by a few degrees, over a period of several days. 19 && .PRELIMINARY POINT TEMPS/POPS... Abilene 73 96 71 96 71 / 5 5 10 5 5 San Angelo 72 96 69 94 71 / 10 10 10 10 5 Junction 72 95 70 94 71 / 20 10 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ Daniels
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1144 AM CDT THU SEP 5 2013 .UPDATE... To expand POPS north... && .DISCUSSION... I sent out a quick update to expand isolated POPS north into the Heartland and Concho Valley this afternoon. A cumulus field is beginning to develop across the region, with low level moisture higher than originally anticipated. High resolution models including the Texas Tech WRF and HRRR are indicating isolated showers and thunderstorms developing this afternoon across the southern half of West Central Texas. For this reason, I have expanded POPS north as previously mentioned. I have also tweaked temperatures down a degree or two across much of the region, given the expected higher dewpoints and increased cloud cover...with the hottest temperatures across the Big Country. Otherwise, no other changes are needed at this time. && .PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/ DISCUSSION... Please see aviation section below for discussion. AVIATION... Look for beautiful flight weather to continue across West Central Texas for the next 24 hours. High pressure will continue to dominate; thus, I`m expecting light surface winds around 6 knots or less for another 24 hours. Huber PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/ SHORT TERM... (today and tonight) Thunderstorms may develop across our Northern Edwards Plateau and Northwest Hill Country counties this afternoon and evening. Otherwise, expect hot and dry conditions to continue for at least another 24 hours. High pressure will remain dominate over the southern Plains for the next 24 hours. Our southern counties will remain just outside the major influence of this high and its associated subsidence. Thus, I`ve decided to continue slight chance POPs across our southern counties, as this area has been an area of convective development during the last couple afternoons. As for temperatures, I`m going with highs today just above the adjusted MEX model data, simply because that`s been the trend the last couple days, with highs just above model guidance. Lows tonight close to persistence look reasonable. Huber LONG TERM... (Friday through Wednesday) The main forecast items of interest in the long term include possible low rain chances in the southern part of our forecast area, and a slow decrease in maximum temperatures over the course of several days. Friday through the weekend, the upper high will slowly weaken as it shifts east across Kansas. Our area will continue to be on the southern periphery of this upper high. The 00Z GFS and NAM are less favorable with QPF across our southern counties on Friday. However, given what has occurred during the past couple of days, plan to continue with low POPs in our southern counties for isolated afternoon and evening showers/thunderstorms across that area, where sufficient moisture should remain. On the fence whether to carry an isolated mention for afternoon/ early evening showers and thunderstorms this weekend across roughly the southern third of West Central Texas. The 00Z models have trended down a bit with mid-level moisture, and mid/upper forcing will be weak. Planning to leave out the mention for now. Early next week the upper level high is progged to shift into the southeastern part of the country, with an upper trough moving east across the northern Plains and into southwestern Ontario Province in Canada. Over our area, the flow aloft will transition to southeasterly through a deeper layer, but with the latest model indications this may be short-lived. The 00Z GFS and ECMWF show more ridging aloft over the northern half of Texas by the middle of next week. With uncertainty in the specifics of how the upper level pattern will evolve next week, holding off with any mentionable rain chance in our counties at this time. With a slight decrease in 850 mb temperatures across our area along with some increase in cloud cover, maximum temperatures are expected to decrease by a few degrees, over a period of several days. 19 && .PRELIMINARY POINT TEMPS/POPS... Abilene 98 73 96 71 96 / 10 5 5 10 5 San Angelo 98 72 96 69 94 / 10 10 10 10 10 Junction 95 72 95 70 94 / 20 20 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ Daniels
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
610 AM CDT THU SEP 5 2013 .DISCUSSION... SEE 12Z AVIATION DISCUSSION. && .AVIATION... MODELS DID NOT INITIALIZE WELL OVERNIGHT. NAM AND GFS SHOW THE BEST OMEGA FIELDS OVER THE NORTHERN TAF SITES WHILE THE HRRR AND 4 KM WRF FAVOR SHRA/TSRA ALONG COAST. AT 09Z...A WEAK TROUGH EXTENDED FROM THE LOUISIANA COASTAL WATERS...NORTHWEST TOWARD KCLL. FCST SOUNDINGS SHOW PW VALUES PEAKING NEAR 2.00 INCHES BETWEEN 21-00Z. THE UPPER RIDGE OVER THE SOUTHERN PLAINS SHOULD IMPART SOME SUBSIDENCE TODAY BUT STILL FEEL HEATING COUPLED WITH 2.0 PW AIR WILL YIELD AFTN SHRA/TSRA. GENERALLY CLEAR SKIES AND LIGHT WINDS OVERNIGHT. COLD BE SHRA NEAR KGLS EARLY FRIDAY MORNING AND MORE OF AN EAST WIND ON FRIDAY. 43 && .PREV DISCUSSION... /ISSUED 435 AM CDT THU SEP 5 2013/ DISCUSSION... ANOTHER WARM AND MUGGY NIGHT ACROSS SOUTHEAST TEXAS THIS MORNING WITH TEMPERATURES IN THE MID 70S IN MOST LOCATIONS. THERE IS A POSSIBILITY OF SOME PATCHY FOG IN RURAL AREAS THIS MORNING (ESPECIALLY AREAS THAT HAVE SEEN RAIN) AS NEARLY CALM WINDS HAS ALLOWED DEWPOINT DEPRESSIONS TO DROP TO AROUND A DEGREE OR TWO IN SOME LOCATIONS. THERE ALSO HAS BEEN SOME RAIN IN THE GULF THIS MORNING AS A WEDGE OF VORTICITY MOVES ACROSS THE AREA. MODELS AGAIN APPEAR TO BE HAVING DIFFICULTY WITH HANDLING MOISTURE VALUES ACROSS THE AREA. ACCORDING TO GPS MET KCLL PWAT VALUES HAVE HELD STEAD AROUND 1.8 - 1.9" THE LAST TWO DAYS WHILE BOTH NAM AND GFS FORECAST SOUNDINGS HAVE SHOWN PWAT VALUES DROPPING TO AROUND 1.6". AGAIN TODAY GFS AND NAM FORECAST SOUNDINGS SHOW PWAT VALUES AROUND 1.6" AND 1.5" RESPECTIVELY. BOTH FORECAST SOUNDINGS ALSO SHOW DRY AIR IN THE MID-LEVELS. THE KLCH 0Z SOUNDING SHOWS A PWAT OF 2.12" WHILE KFWD 0Z SOUNDINGS SHOWS A PWAT OF ONLY 1.10". GIVEN THE GPS MET DERIVED PWAT FEEL THAT OUR AREA IS MORE REPRESENTED BY THE KLCH SOUNDING. GFS AND NAM OMEGA FIELDS ARE HINTING AT LIFT NORTH OF I-10 TODAY AND GIVEN THE MOISTURE VALUES IN PLACE SCATTERED SHOWERS AND THUNDERSTORMS AGAIN LOOK POSSIBLE. BEST UPPER LEVEL DIFFLUENCE STILL APPEARS TO BE OFF TO THE EAST TODAY THOUGH. THE UPPER LEVEL RIDGE CURRENTLY OVER COLORADO WILL CONTINUE TO MOVE EASTWARDS THIS WEEKEND. THE TROPICAL WAVE CURRENTLY LOCATED OVER THE YUCATAN WILL DRIFT EASTWARD FRIDAY INTO SATURDAY. WITH THE RIDGE TO THE NORTH THE BEST CHANCES OF RAIN APPEAR TO BE IN THE SOUTHERN ZONES AND OFFSHORE WATERS. THE NEXT TROPICAL WAVE WILL APPROACH THE AREA LATE TUESDAY INTO EARLY WEDNESDAY. THE GFS WEAKENS THE UPPER LEVEL RIDGE ALLOWING THE WAVE TO DRIFT FARTHER NORTHWARDS WILL THE ECMWF SHOWS A SLIGHTLY STRONGER RIDGE WHICH KEEPS THE WAVE FURTHER SOUTH. A SLIGHT DEVIATION IN THE TRACK OF THE UPPER LEVEL RIDGE COULD DRASTICALLY CHANGE TO AMOUNT OF RAIN SEEN ACROSS THE REGION. MODELS HAVE ALSO SHOWN LITTLE CONSISTENCY ON THIS FEATURE THE LAST COUPLE OF DAYS. MADE ONLY MINOR CHANGES TO POPS GIVEN LACK OF CONSISTENCY IN MODELS. 23 MARINE... A RELATIVELY WEAK PRESSURE GRADIENT WILL REMAIN IN PLACE WITH LIGHT ONSHORE WINDS EXPECTED. A SERIES OF WEAK EASTERLY WAVES WILL MOVE INTO MEXICO WITH THE FIRST WAVE MOVING TOWARD THE MEXICAN COAST ON TONIGHT INTO FRIDAY AND A SECOND STRONGER WAVE MOVING INLAND ON SUNDAY. THIS SHOULD SUPPORT EASTERLY WINDS AND SEAS AROUND 3 FEET. SLIGHTLY HIGHER SEAS WILL BE POSSIBLE SUN-MON DUE TO PERSISTENT EAST TO SOUTHEAST WINDS. THE PERSISTENT E-SE WINDS WILL ALSO PRODUCE A SUBTLE INCREASE IN TIDE LEVELS. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 98 75 98 75 97 / 30 10 20 10 20 HOUSTON (IAH) 97 76 97 75 96 / 30 20 20 20 20 GALVESTON (GLS) 90 80 89 80 89 / 30 20 30 20 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...23 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1135 PM CDT WED SEP 4 2013 .DISCUSSION... /See below for aviation discussion/ && .AVIATION... VFR next 24 hours. Isolated afternoon and evening thunderstorms are possible Thursday afternoon and evening at KSOA, KJCT, and KBBD. Coverage however is expected to be too low for mention in TAFS. Light winds tonight become southeast to south at 10 mph or less Thursday. 04 && .PREV DISCUSSION... /ISSUED 936 PM CDT WED SEP 4 2013/ .UPDATE... Most of the convective activity that developed this afternoon across West Central TX has dissipated. However, we are seeing storms over the I-35 corridor from Waco to near San Antonio holding together, continuing a general westerly trend. While most of this activity will continue to weak, the HRRR is suggesting additional shower development tonight across mainly the Heartland Counties overnight (namely Brown, Coleman, San Saba, and McCulloch Counties). I trimmed PoPs back across the southwest counties for the remainder of the overnight period and extended the mention of isolated thunderstorms through 08z to account for this possibility. Dewpoints across the Big Country tanked into the mid 30s this afternoon due to strong subsidence and associated dry air mixing to the surface. This brought precipitable water values below 1 inch across the northwest half of the forecast area with pwats near 1.4 inches across the southeast. The bulk of the deeper moisture will remain to our south and east through tomorrow but we will see similar pwat values again tomorrow, suggesting the potential for additional diurnal convection, especially across the southern half of the area. For tonight, dewpoints will be slow to recover and should allow temperatures to fall into the upper 60s, especially in areas where cloud cover will be sparse. Min temps were updated accordingly. Johnson && .PREV DISCUSSION... /ISSUED 552 PM CDT WED SEP 3 2013/ DISCUSSION... /See below for aviation discussion/ AVIATION... VFR next 24 hours. Isolated thunderstorms possible Thursday afternoon south of the I-20 corridor. However potential is too low to include in TAFS. 04 PREV DISCUSSION... /ISSUED 352 PM CDT WED SEP 3 2013/ SHORT TERM...(Tonight and Thursday) Isolated showers and a few storms possible this afternoon and early this evening, and again on Thursday afternoon and evening. West Central Texas remains on the edge of the large upper level high pressure dominating much of the southern plains. Abundant moisture with east winds prevailing at most levels will combine with afternoon temperatures climbing into the mid 90s to produce a few storms. These storms will mainly be along the edge of the ridge axis itself, across the southern and eastern portions of the area. Have inserted a mention of storms into the forecast itself through the early evening hours tonight and again for a few hours Thursday afternoon. Otherwise, clouds having an impact on temperatures this afternoon and expect of the same tomorrow. Readings in the mid and upper 90s across the northern half of the area, while the southern half of the area runs in the lower 90s. LONG TERM...(Thursday Night through Wednesday) The upper ridge will remain centered over the Southern Plains through this weekend with above normal temperatures continuing. Cannot rule out isolated convection developing again across far southern counties Friday afternoon/early evening so will include this potential this forecast cycle. By early next week, a short wave trough will move east across the Northern Plains and across the Great Lakes region by mid week. This system will push the upper high east of the area for the latter part of the extended period and allow afternoon highs to cool a few degrees. The upper high will be situated over the Ohio and Tennessee Valleys, which will result in deeper low to mid level southeasterly flow across the area. This pattern would be more favorable for diurnal convection, especially across southeast sections Monday through Wednesday of next week. Kept the forecast dry for now given uncertainties this far out and wait to see how models perform in subsequent runs before considering adding POPS to the forecast. && .PRELIMINARY POINT TEMPS/POPS... Abilene 68 96 71 96 71 / 0 5 5 5 5 San Angelo 69 95 69 96 70 / 5 10 10 10 10 Junction 68 95 69 95 70 / 10 10 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 25
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1002 PM CDT FRI SEP 6 2013 .UPDATE... NO CHANGES TO GOING FORECAST. LATEST NAM HOLDS ANY PCPN IN THE CWA TO THE FAR NORTHWEST CLOSE TO THE APPROACHING FRONT/TROUGH... MAINLY AROUND/AFTER 09Z. 00Z HRRR EVEN MORE MEAGER WITH PCPN THROUGH 10Z THAN EARLIER RUNS...AND SIMILAR TO LATEST NAM WITH THE NW CWA SEEING ONLY A SLIGHT CHANCE BEFORE 12Z. && .AVIATION/06Z TAFS/... KEEPING VFR CONDITIONS AND NO PCPN AT ANY TAF SITES UNTIL AFTER 12Z. LATEST MODELS STILL INDICATING GROWING INSTABILITY DURING THE DAY TO PRODUCE POTENTIAL OF SCATTERED SHOWERS/THUNDERSTORMS SATURDAY AFTERNOON. CONFIDENCE IS STILL LIMITED SO WILL STAY WITH VICINITY THUNDER FOR NOW AND AWAIT REST OF THE MODEL GUIDANCE. && .MARINE... LATEST NAM RUN COMING IN WITH SUSTAINED 15 KNOT NORTHEAST WINDS BEHIND COLD FRONT...BEGINNING AROUND/AFTER MIDNIGHT SATURDAY NIGHT AND CONTINUING THROUGH THE DAY SUNDAY...WITH BUFKIT SOUNDINGS INDICATING MIXING UP TO 23 TO 26 KNOT WINDS JUST OFF THE SURFACE INTO THE LATE MORNING...THEN SLOWLY EASING AND BECONING MORE EASTERLY DURING THE AFTERNOON. GOOD POTENTIAL FOR SMALL CRAFT CONDITIONS FROM OVERNIGHT SATURDAY NIGHT THROUGH SUNDAY AFTERNOON...INITIALLY FOR WINDS THAT BUILD HIGH WAVES...THEN FOR WAVES THAT WILL BE SLOWER TO SUBSIDE AFTER THE WINDS EASE. && .PREV DISCUSSION... /ISSUED 330 PM CDT FRI SEP 6 2013/ TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM. A WEAK SHORTWAVE/VORT MAX RIDING OVER AN UPPER LEVEL RIDGE CENTERED OVER THE GREAT PLAINS WILL CROSS CENTRAL WI OVERNIGHT...ALONG THE 850-700MB THERMAL RIDGE...AND CLEAR SOUTHEAST WI AROUND 15Z SATURDAY. THE MAIN MOISTURE TRANSPORT OVERNIGHT WILL BE NORTH OF THE MKX FORECAST AREA /CWA/...SO KEPT THUNDER MENTION OUT UNTIL EARLY SATURDAY MORNING. AFTER 09Z...THE DEEPER MOISTURE WILL MAKE IT INTO MAINLY THE EASTERN CWA...COINCIDENT WITH THE MID LEVEL SHORTWAVE. MODEL SOUNDINGS SHOW INCREASING MID LEVEL LAPSE RATES WITH THIS FEATURE SO ELEVATED THUNDERSTORMS WILL BE POSSIBLE EARLY SATURDAY MORNING THROUGH NOONISH. PRECIP COVERAGE ALONG THE COLD FRONT SATURDAY AFTERNOON AND EVENING IS UNCERTAIN. MANY OF THE HI-RES MODELS SHOW SCATTERED CONVECTION NEAR THE FRONT AT BEST. SPC HAS SOUTHERN WI IN A SEE TEXT AREA GIVEN THE POTENTIAL FOR A FEW THUNDERSTORMS TO TAP INTO THE HIGHER CAPE IN POCKETS OF STRONGER HEATING AND BOUNDARY LAYER DESTABILIZATION AND PRODUCE STRONG TO SEVERE WIND GUSTS. THIS IS ONLY IF THUNDERSTORMS CAN DEVELOP. KEPT THE CHANCE POPS IN THE FORECAST FOR NOW. NOT EVEN CONFIDENT ENOUGH TO GO WITH SCATTERED WORDING. SHORT TERM...SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH. SHORT TERM MODELS IN GOOD AGREEMENT WITH SLIDING COLD FRONT SOUTHWARD THROUGH THE AREA SATURDAY EVENING. LEFT POPS IN FORECAST FOR AREAS ALONG AND AHEAD OF THE FRONT. INCREASING NORTHEAST WINDS WITH TIGHTENING PRESSURE GRADIENT BEHIND FRONT WILL BRING COOLER AND DRIER AIR INTO THE AREA LATER SATURDAY NIGHT INTO SUNDAY. THIS A RESULT OF HIGH PRESSURE SLIDING SOUTHEAST THROUGH THE CENTRAL GREAT LAKES REGION. MODELS ALSO HINTING AT AN AREA OF LOW CLOUDS MOVING SOUTHWESTWARD THROUGH THE AREA DURING THIS TIME. COLD AIR ADVECTION AND THE CLOUDS SHOULD KEEP HIGHS IN THE 70S...COOLEST NEAR THE LAKE. 850MB WARM AIR ADVECTION KICKS IN SUNDAY NIGHT AND ESPECIALLY MONDAY ACROSS THE REGION. BEST FOCUS FOR UPWARD VERTICAL MOTION WILL REMAIN NORTH OF THE AREA DURING THIS TIME. HOWEVER...AREA FORECAST SOUNDINGS DO SHOW ELEVATED CAPE INCREASING DURING THIS TIME. MODELS NOT SHOWING MUCH QPF. AREA IS ON PERIPHERY OF THE 850MB WARM AIR ADVECTION...SO COULD NOT COMPLETELY RULE OUT A SHOWER OR STORM...MAINLY MONDAY MORNING. LEFT LOW END POPS IN FORECAST FOR MONDAY MORNING. MOST OF THE DAY SHOULD BE DRY. VERY WARM AND HUMID CONDITIONS WILL RETURN MONDAY...WITH MID TO UPPER 80S INLAND...SOMEWHAT COOLER LAKESIDE. LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH. GFS/ECMWF IN FAIR AGREEMENT WITH BRINGING COLD FRONT TOWARD THE AREA MONDAY NIGHT...THEN EASTWARD ACROSS THE AREA TUESDAY INTO TUESDAY NIGHT. CONTINUED HIGHER END CHANCE POPS FOR MAINLY TUESDAY NIGHT...SLOWLY TAPERING OFF ON WEDNESDAY. VERY WARM AND HUMID CONDITIONS WILL CONTINUE TUESDAY...WITH MID TO UPPER 80S. COULD BE WARMER BUT SOME CLOUDS MAY LIMIT HIGHS. HIGH PRESSURE THEN SLIDES SOUTHEAST INTO THE REGION FOR THE REST OF THE WEEK...BRINGING COOLER AND LESS HUMID CONDITIONS. QUIET WEATHER IS EXPECTED. AVIATION/00Z TAFS/...VFR CONDITIONS THROUGH TNT ACROSS SRN WI. A MID LEVEL CLOUD DECK WILL DEVELOP LATE TNT WITH A SLIGHT CHANCE OF LGT SHOWERS. A FEW ELEVATED THUNDERSTORMS COULD DEVELOP SATURDAY MORNING TOWARD SOUTHEAST WI. THEN A FEW TO SCATTERED THUNDERSTORMS ARE EXPECTED IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN THROUGH SOUTHERN WI SATURDAY AFTERNOON AND EVENING. LOW STRATUS CLOUDS POSSIBLE BEHIND THE FRONT SATURDAY NIGHT INTO SUNDAY MORNING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...REM TONIGHT/SATURDAY AND AVIATION/MARINE...MRC SATURDAY NIGHT THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
332 PM CDT THU SEP 5 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 332 PM CDT THU SEP 5 2013 MAIN FORECAST CONCERNS ARE ON HIGH TEMPERATURES ON FRIDAY AND SHOWER AND THUNDERSTORM CHANCES FRIDAY NIGHT INTO SATURDAY. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED HIGH PRESSURE CENTERED OVER EASTERN COLORADO WITH A RIDGE EXTENDING NORTH THROUGH THE DAKOTAS INTO SOUTHERN SASKATCHEWAN. AN UPPER LOW WAS NOTED JUST OFF OF THE PACIFIC NORTHWEST...WHILE A BROAD TROUGH WAS IN PLACE OVER EASTERN CANADA. NORTHWEST FLOW ALOFT WAS NOTED OVER THE UPPER MISSISSIPPI RIVER VALLEY. SEVERAL WEAK EMBEDDED SHORTWAVES WERE NOTED OVER THE DAKOTAS. THE PRIMARY WAVE WAS LOCATED OVER WESTERN NORTH DAKOTA...HEADED SOUTHEAST. HIGH PRESSURE WAS CENTERED OVER THE WESTERN GREAT LAKES WHILE A STATIONARY BOUNDARY WAS LOCATED OVER THE EASTERN DAKOTAS AND WAS STRETCHING SOUTHEAST THROUGH CENTRAL IOWA INTO SOUTHERN ILLINOIS. THE HIGH WILL SLIDE EAST OF THE REGION TONIGHT AS THE SHORTWAVE APPROACHES FORM THE DAKOTAS/WESTERN MINNESOTA. SOUTHERLY FLOW WILL INCREASE ON THE BACK SIDE OF THE HIGH USHERING IN A WARMER AND SLIGHTLY MORE HUMID AIRMASS. 850 MB MOISTURE TRANSPORT INCREASES ACROSS WESTERN MINNESOTA AND WESTERN IOWA...WHICH SHOULD RESULT IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THE MOISTURE TRANSPORT ATTEMPTS TO EDGE INTO NORTHEAST IOWA AND SOUTHEAST MINNESOTA LATE TONIGHT INTO EARLY FRIDAY MORNING WHICH MAY SUPPORT AN ISOLATED SHOWER OR THUNDERSTORM. FORECAST SOUNDINGS ARE RATHER DRY AND WITHOUT A STRONG FORCING MECHANISM HAVE DECIDED TO MAINTAIN A DRY FORECAST FOR THE OVERNIGHT HOURS. CANNOT RULE OUT SOME PATCHY VERY SHALLOW FOG IN COULEE AREAS TONIGHT BUT THAT SHOULD BE THE EXTENT OF IT. THE GRADIENT TIGHTENS OVER THE REGION TONIGHT AND WINDS FROM 500 TO 1KFT INCREASE TO 16 TO 25KTS...WHICH SHOULD PROMOTE ENOUGH MIXING TO PREVENT DENSE FOG FORMATION. FRIDAY WILL BE A WARM AND BREEZY DAY ACROSS THE REGION AHEAD OF A WEAK COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. PLAN ON HIGHS RANGING FROM THE LOWER 80S OVER FAR NORTHERN WISCONSIN TO THE UPPER 80S TO AROUND 90 OVER NORTHEAST IOWA. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 332 PM CDT THU SEP 5 2013 THE FRONT WILL MOVE THROUGH THE FORECAST AREA FRIDAY NIGHT INTO SATURDAY MORNING BRINGING CHANCES FOR SHOWERS AND STORMS WITH IT. THERE IS ELEVATED CAPE OVER THE REGION WITH VERY LITTLE TO NO CAP IN PLACE. LIFTING FROM 800 MB YIELDS NEARLY 700 J/KG CAPE. ALSO...850 MB MOISTURE TRANSPORT FOCUSES INTO THE AREA SO THERE SHOULD BE ENOUGH SUPPORT FOR AT LEAST ISOLATED TO SCATTERED THUNDERSTORMS. THE BEST CHANCES FOR THESE APPEARS TO BE ALONG AND EAST OF THE MISSISSIPPI RIVER. HIGH PRESSURE GRADUALLY BUILDS INTO THE AREA LATE SATURDAY AFTERNOON THROUGH SUNDAY. PRECIPITATION CHANCES WILL SHIFT SOUTHEAST OF THE FORECAST AREA BY LATE SATURDAY AFTERNOON AS THE HIGHS BUILDS IN. THE HIGH WILL BE CENTERED OVER LAKE SUPERIOR ON SUNDAY PROVIDING DRY EAST/NORTHEAST FLOW. HAVE LOWERED DEW POINTS SIGNIFICANTLY ALONG AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WHERE DEEP MIXING WILL YIELD AFTERNOON RELATIVE HUMIDITY VALUES IN THE MID 30S. THE HIGH WILL SLIDE EAST OF THE REGION SUNDAY NIGHT INTO MONDAY AS A VIGOROUS TROUGH RACES ACROSS NORTH DAKOTA AND NORTHERN MINNESOTA. VERY WARM IS ADVECTS NORTHWARD AHEAD OF THIS FEATURE INTO THE FORECAST AREA WITH 925 MB TEMPERATURES WARMING INTO THE UPPER 20S TO AROUND 30. DECIDED TO WARM HIGH TEMPERATURES ON MONDAY INTO THE UPPER 80S TO LOWER 90S...CLOSER TO WHAT THE ECMWF IS ADVERTISING. THERE IS THE POTENTIAL FOR SHOWERS AND STORMS ALONG AND NORTH OF INTERSTATE 90 ON MONDAY SO TEMPERATURES MAY NOT GET THAT WARM ACROSS THESE AREAS. ZONAL FLOW LOOKS TO SET UP OVER THE REGION ON TUESDAY INTO TUESDAY NIGHT WITH EMBEDDED SHORTWAVES POSSIBLY GENERATING SOME SHOWERS AND STORMS OVER THE FORECAST AREA. THE ECMWF IF ADVERTISING BETTER CHANCES FOR PRECIPITATION ON WEDNESDAY AS A TROUGH DIVES SOUTH OUT OF CANADA. THE GFS IS NOT NEARLY AS AGGRESSIVE WITH THIS FEATURE AND BRINGS THE BULK OF THE PRECIPITATION THROUGH TUESDAY INTO TUESDAY NIGHT WITH THE PASSAGE OF A COLD FRONT. CONSIDERABLE UNCERTAINTY IN THE FORECAST BEYOND MONDAY SO CHOSE TO LEAN TOWARD A MODEL CONSENSUS BLEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1207 PM CDT THU SEP 5 2013 THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL. THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1207 PM CDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 346 AM CDT THU SEP 5 2013 CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE I-94 CORRIDOR. FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY. RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S. ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF 850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 346 AM CDT THU SEP 5 2013 ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE LOCATIONS FLIRTING WITH THE 90 DEGREE MARK. FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS... LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS THE AREA. SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM ONTARIO CANADA INTO THE GREAT LAKES REGION. LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA. WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND 35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY. THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY INT THE UPPER 70S TO MIDDLE 80S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1207 PM CDT THU SEP 5 2013 THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL. THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
615 AM CDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 346 AM CDT THU SEP 5 2013 CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE I-94 CORRIDOR. FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY. RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S. ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF 850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 346 AM CDT THU SEP 5 2013 ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE LOCATIONS FLIRTING WITH THE 90 DEGREE MARK. FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS... LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS THE AREA. SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM ONTARIO CANADA INTO THE GREAT LAKES REGION. LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA. WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND 35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY. THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY INT THE UPPER 70S TO MIDDLE 80S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 615 AM CDT THU SEP 5 2013 IN WHAT HAS BEEN A VFR REGIME HAS SOME CHALLENGES THIS MORNING AS LOW LEVEL STRATUS DECK ADVECTING IN FROM THE EAST IS APPROACHING MISSISSIPPI RIVER AT DAYBREAK WITH PATCH OF IFR CEILINGS. HOW FAR WEST IT MIGRATES AND HOW LONG IT MIGHT LAST IS PROBLEMATIC. MOST WISCONSIN LOCALES DEALING WITH IFR CONDITIONS...WHILE WEST OF THE RIVER VFR CONDITIONS STILL PREVAIL. FEELING IS STRATUS DECK WILL CONTINUE TO PUSH WEST THIS MORNING AND THEN PROBABLY HANG UP FOR MUCH OF THE MORNING BEFORE EARLY SEPTEMBER SUN BEGINS TO BREAK IT UP. SHORT TERM GUIDANCE SUGGEST DRY LAYERS ABOVE IT SHOULD HELP TO BREAK IT UP SOMETIME THIS MORNING BUT THIS WILL HAVE TO WATCHED. VFR CONDITIONS SHOULD RETURN LATER IN THE DAY AND AS SOUTHEAST FLOW DEVELOPS TONIGHT...COULD SEE SOME MVFR VISIBILITIES RETURN AS MOISTURE REMAINS HUNG UP ALONG BOUNDARY SITTING JUST TO THE SOUTH. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 AM CDT THU SEP 5 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 346 AM CDT THU SEP 5 2013 CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE I-94 CORRIDOR. FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY. RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S. ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF 850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 346 AM CDT THU SEP 5 2013 ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE LOCATIONS FLIRTING WITH THE 90 DEGREE MARK. FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS... LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS THE AREA. SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM ONTARIO CANADA INTO THE GREAT LAKES REGION. LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA. WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND 35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY. THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY INT THE UPPER 70S TO MIDDLE 80S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1143 PM CDT WED SEP 4 2013 THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE 3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE MORNING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT WED SEP 4 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 337 PM CDT WED SEP 4 2013 MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON TEMPERATURES AND CLOUD COVER TONIGHT INTO THURSDAY MORNING. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED RIDGING ACROSS ANCHORED OVER THE ROCKIES. TWO UPPER LOWS NOTED...ONE CENTERED OVER THE EASTERN SHORE OF HUDSON BAY...AND THE OTHER WAS JUST EDGING INTO THE PACIFIC NORTHWEST. A WEAK COLD FRONT STRETCHED FROM CENTRAL MINNESOTA ACROSS CENTRAL WISCONSIN EAST THROUGH NORTHERN LOWER MICHIGAN AND WAS SLOWLY DRIFTING SOUTH. THERE HAS NOT BEEN ANY PRECIPITATION ASSOCIATED WITH THE FRONT JUST A SLIGHT INCREASE IN CLOUD COVER. SURFACE HIGH PRESSURE WILL BUILD INTO THE FORECAST AREA TONIGHT AS THE COLD FRONT SLIDES SOUTH INTO CENTRAL IOWA AND SOUTHERN ILLINOIS. THE STRATUS CURRENTLY OVER NORTHERN WISCONSIN...SLIPS SOUTHWEST TONIGHT. LINGERING MOISTURE CENTERED AROUND 850 MB...WITH AN ADDITIONAL POCKET LOCATED IN THE 700-450 MB LAYER...MAY BE ENOUGH TO GENERATE SOME CLOUD COVER TONIGHT OVER NORTHEAST IOWA....SOUTHEAST MINNESOTA...AND SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SUGGEST THE LOWER LEVEL MOISTURE WILL DRY OUT AS THE HIGH BUILDS IN. IF THE CLOUD COVER LINGERS IT WILL HAVE AN IMPACT ON FOG POTENTIAL AND TEMPERATURES OVERNIGHT. PLAN ON PARTLY CLOUDY TO MOSTLY CLEAR SKIES TONIGHT WITH LOW TEMPERATURES RANGING FROM THE UPPER 30S TO LOWER 40S OVER NORTHERN WISCONSIN TO THE MID TO UPPER 50S ACROSS NORTHEAST IOWA. HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY PROVIDING DRY AND QUIET WEATHER. THE MAIN CONCERN WILL BE ON AFTERNOON DEWPOINTS...ESPECIALLY CLOSER TO THE CENTER OF THE HIGH OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. FORECAST SOUNDINGS SHOW DRY AIR ALOFT WITH DEEP MIXING TO NEARLY 875 MB. LOOKING UPSTREAM ACROSS UPPER MICHIGAN AND SOUTHERN ONTARIO...DEWPOINTS ARE ONLY IN THE UPPER 30S TO LOWER 40S AND THIS AIR IS ADVECTING SOUTHWARD. HAVE LOWERED AFTERNOON DEWPOINTS INTO THE LOWER 40S OVER WEST CENTRAL THROUGH CENTRAL WISCONSIN WHERE DEEP MIXING SHOULD EASILY YIELD THESE AFTERNOON VALUES. THIS WOULD PRODUCE RELATIVE HUMIDITY VALUES IN THE 27 TO 30 PERCENT RANGE. THERE WILL NOT BE MUCH WIND UNDER THE HIGH WITH WIND MAINLY LIGHT AND VARIABLE AT 5 MPH OR LESS OVER THESE AREA. OTHERWISE...PLAN ON SKIES RANGING FROM PARTLY TO MOSTLY CLOUDY OVER SOUTHEAST MINNESOTA INTO NORTHEAST IOWA...TO MOSTLY SUNNY OVER NORTH CENTRAL WISCONSIN. A WEAK SHORTWAVE LOOKS TO MOVE ACROSS AREAS ALONG AND WEST OF THE MISSISSIPPI RIVER WITH THE MAIN IMPACT BEING AN INCREASE IN CLOUD COVER. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 337 PM CDT WED SEP 4 2013 THE HIGH WILL SLIDE EAST INTO THE EASTERN GREAT LAKES THURSDAY NIGHT INTO FRIDAY. A COLD FRONT IS EXPECTED TO PUSH INTO NORTHWEST MINNESOTA AND EASTERN SOUTH DAKOTA BY FRIDAY AFTERNOON. SOUTHERLY FLOW WILL INCREASE ACROSS THE AREA ON FRIDAY AS THE FRONT APPROACHES HELPING TO USHER IN A WARMER AND SLIGHTLY MORE HUMID AIRMASS. 925 MB TEMPERATURES WARM TO AROUND 25 ACROSS WESTERN AND CENTRAL WISCONSIN AND TO THE UPPER 20S ACROSS PORTIONS OF NORTHEAST IOWA AND SOUTHEAST MINNESOTA. HIGH TEMPERATURES ARE EXPECTED TO WARM INTO THE MID 80S...WITH A FEW UPPER 80S POSSIBLE ALONG THE MISSISSIPPI RIVER VALLEY AND CLOSER TO THE INTERSTATE 35 CORRIDOR. FORECAST MODELS ARE ADVERTISING A WEAK SHORTWAVE MOVING ACROSS THE EASTERN DAKOTAS AND PUSHING INTO THE UPPER MISSISSIPPI RIVER VALLEY LATE THURSDAY NIGHT INTO EARLY FRIDAY MORNING. 850 MB MOISTURE TRANSPORT IS WEAK AND FOCUSED INTO SOUTHWEST MINNESOTA AND WESTERN IOWA THURSDAY EVENING THEN ATTEMPTS TO SHIFT EAST INTO THE AREA EARLY FRIDAY MORNING. THERE ISN/T MUCH UPPER LEVEL SUPPORT FOR PRECIPITATION SO DECIDED TO MAINTAIN A DRY FORECAST DURING THIS TIMEFRAME. THE FRONT IS EXPECTED TO PUSH SOUTHEAST FRIDAY NIGHT INTO SATURDAY POSSIBLY INTERACTING WITH WEAK UPPER LEVEL IMPULSES IN NORTHWEST FLOW ALOFT. THIS WILL BRING SLIGHT CHANCES FOR SHOWERS AND STORMS TO THE FORECAST AREA FRIDAY NIGHT INTO SATURDAY. THE PACIFIC NORTHWEST TROUGH FINALLY MOVES EAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY NIGHT BREAKING DOWN THE PERSISTENT RIDGING OVER THE UPPER MIDWEST. THIS WILL BRING CHANCES FOR SHOWERS AND STORMS TO THE FORECAST AREA...ESPECIALLY SUNDAY NIGHT INTO MONDAY NIGHT. WARM SOUTHERLY FLOW WILL CONTINUE INTO EARLY NEXT WEEK. HIGHS WILL REMAIN WELL ABOVE NORMAL THROUGH THE WEEKEND WITH SATURDAY LOOKING TO BE THE WARMEST DAY WITH HIGHS IN THE MID TO UPPER 80S. THE WARM TEMPERATURES WILL CONTINUE THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1143 PM CDT WED SEP 4 2013 THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE 3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE MORNING HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
359 AM MDT SAT SEP 7 2013 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 358 AM MDT SAT SEP 7 2013 ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA ACTIVITY APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH NORTHWEST ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT FIELDS ON THE 00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING TOWARD THE FOUR CORNERS THIS MORNING...BEFORE DAMPENING OUT SHORTLY AFTER SUNRISE. THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL CONTINUE FOR ANOTHER COUPLE HOURS. HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY... WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS. TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL. SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL. GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY ESPECIALLY OVER NE UT-FAR NW CO. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 358 AM MDT SAT SEP 7 2013 SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST NEAR THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL BELOW 14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS. TEMPERATURES FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY. DRIER AIR TRIES TO INVADE NE UTAH MONDAY NIGHT. THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN EXPERIENCING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 358 AM MDT SAT SEP 7 2013 ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH THIS MORNING...AND BECOME MORE WIDESPREAD THIS AFTERNOON. GUSTY AND ERRATIC OUTFLOW WINDS...HEAVY RAIN AND SMALL HAIL WILL BE ASSOCIATED WITH STRONGER THUNDERSTORMS THROUGH 03Z THIS EVENING. MOISTURE WILL CONTINUE TO SURGE BACK INTO THE REGION AFTER 06Z TONIGHT WITH SHOWERS LINGERING THROUGH THE NIGHT. EXPECT LOCAL MVFR CIGS AND VSBYS NEAR THE STRONGER THUNDERSTORMS TODAY...ESPECIALLY ACROSS THE MOUNTAINS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...JDC/JOE LONG TERM...JOE/JDC AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 AM EDT SAT SEP 7 2013 .AVIATION... FOR THE SHORT TERM...THERE ARE SOME THUNDERSTORMS IN THE NEAR SHORE ATLANTIC WATERS TO THE EAST OF TERMINAL TPBI AND SHOWERS THAT WILL LIKELY IMPACT THE TERMINAL FOR ABOUT THE NEXT 15 TO 30 MINUTES WITH PERIODS OF SUB-VFR CONDITIONS POSSIBLE AND WITH VERY BRIEF IFR CONDITIONS POSSIBLE IN THIS TIME FRAME. THE CONVECTION AFFECTING TERMINAL KPBI IS STARTING TO BREAK UP WITH VCTS ASSIGNED UNTIL 07Z...WILL AMEND AS NECESSARY. OTHERWISE...WITH EASTERLY FLOW ACROSS THE ATLANTIC WATERS AND LINGERING BOUNDARIES FROM CONVECTION EARLIER THIS EVENING A FEW SHOWERS AND/OR ISOLATED THUNDERSTORMS COULD POP UP BUT MAINLY VFR CONDITIONS EXPECTED FOR THE REMAINING EAST COAST TERMINALS AND TERMINAL KAPF THE REMAINING EARLY MORNING HOURS. 60 && .PREV DISCUSSION... /ISSUED 847 PM EDT FRI SEP 6 2013/ UPDATE... ALTHOUGH IT WAS A LATE START FOR THE AFTERNOON SHOWERS AND STORMS...A LARGE AREA OF HEAVY SHOWERS AND STORMS HAS DEVELOPED AND BECOME FOCUSED OVER THE GULF COAST AREAS FROM NAPLES TO EVERGLADE CITY TO CENTRAL COLLIER COUNTY THIS EVENING. THE LATEST RADAR SCAN ESTIMATED TOTALS RANGING FROM HALF OF AN INCH OVER THE BULK OF THIS AREA WITH ISOLATED AMOUNTS AS HIGH AS 2.5". THE LATEST HRRR MODEL REFLECTIVITIES LINE UP WELL WITH THIS ACTIVITY AND GENERALLY CONTINUES TO SUPPORT THIS COVERAGE WELL INTO THE LATE EVENING HOURS BEFORE DISSIPATING. IF THIS VERIFIES...AN ADDITIONAL HALF OF AN INCH TO ONE INCH WITH LOCALLY HIGHER AMOUNTS WILL BE EXPECTED. THE LATEST FORECAST PACKAGE HAS BEEN UPDATED TO REFLECT THESE LATEST TRENDS. OTHERWISE...THE PREVIOUS FORECAST REMAINS ON TRACK THIS EVENING. PREV DISCUSSION... /ISSUED 736 PM EDT FRI SEP 6 2013/ AVIATION... VFR PREVAILING AT ALL TERMINALS. VCTS ONLY FOR KAPF THIS EVENING DUE TO THE ACTIVITY ALREADY NEARBY. EXPECT THIS TO DISSIPATE BY 04Z. VCSH WILL POSSIBLY DEVELOP NEAR ALL EASTERN TERMINALS BY 07/16Z AND WEST COAST SEA BREEZE DEVELOPING BY 07/18Z. VCTS WILL BE POSSIBLE NEAR KAPF BY THAT TIME ALSO. PREV DISCUSSION... /ISSUED 230 PM EDT FRI SEP 6 2013/ TYPICAL SUMMER TIME WEATHER THIS WEEKEND BEFORE DRIER CONDITIONS EARLY NEXT WEEK... SHORT TERM... THE EAST AND WEST COAST SEA BREEZES HAVE DEVELOPED EARLY THIS AFTERNOON WITH THE EAST COAST SEA BREEZE PUSHING ACROSS THE INTERIOR AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH WEST ACROSS SOUTH FLORIDA THROUGH THE AFTERNOON HOURS...AS THE WEST COAST SEA BREEZE REMAINS OVER THE WEST COAST METRO AREAS. AT THE SAME TIME...A TROUGH OF LOW PRESSURE OVER NORTH FLORIDA WILL CONTINUE TO MOVE SOUTH INTO CENTRAL FLORIDA. THIS WEATHER PATTERN WILL ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE INTERIOR AND WEST COAST METRO AREAS THIS AFTERNOON INTO EARLY THIS EVENING...WITH ISOLATED SHOWERS ONLY FOR THE EAST COAST METRO AREAS. SO WILL KEEP THE 30 TO 50 PERCENT POPS IN PLACE FOR THE INTERIOR AND WEST COAST METRO AREAS THROUGH EARLY THIS EVENING...WITH ONLY A 20 PERCENT POPS OVER THE EAST COAST METRO AREAS OF SOUTH FLORIDA. THE TROUGH OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY TONIGHT OVER CENTRAL FLORIDA...BEFORE MOVING SLOWLY SOUTH INTO THE LAKE OKEECHOBEE AREA ON SATURDAY AND THROUGH SOUTH FLORIDA ON SUNDAY. THIS WILL KEEP THE STEERING FLOW OVER SOUTH FLORIDA IN A LIGHT NORTHEAST DIRECTION ALONG WITH THE SEA BREEZE DEVELOPMENT EACH DAY ALONG BOTH COAST. SO THE SCATTERED POPS WILL REMAIN OVER THE INTERIOR AND WEST COAST METRO AREAS WITH ISOLATED POPS OVER THE EAST COAST METRO AREAS EACH DAY THIS WEEKEND. THE THREAT OF THUNDER WILL ALSO BE FOCUS MAINLY OVER THE INTERIOR AND WEST COAST METRO AREAS EACH DAY THIS WEEKEND..BUT THE EAST COAST METRO AREAS COULD SEE A THUNDERSTORM OR TWO. THE 500 MB TEMP WILL ALSO REMAIN VERY COLD FOR THIS TIME OF YEAR IN THE -8C TO -9C OVER SOUTH FLORIDA. THIS WILL ALLOW FOR SOME OF THE STORMS EACH DAY THIS WEEKEND TO BECOME STRONG OVER SOUTH FLORIDA ESPECIALLY WHERE THE SEA BREEZES COLLIDE EACH DAY. THE PRIMARY IMPACTS FROM THE STRONG STORMS WILL MORE LIKELY BE LIGHTNING STRIKES, GUSTY WINDS, AND HAIL. SO WILL MENTION THIS IN THE AFTERNOON HWO PACKAGE. LONG TERM... THE TROUGH OF LOW PRESSURE WILL MOVE INTO THE FLORIDA KEYS EARLY NEXT WEEK BEFORE MOVING BACK UP INTO SOUTH FLORIDA FOR THE MIDDLE OF NEXT WEEK...AS AN UPPER LEVEL LOW DEVELOPS OVER THE WESTERN ATLANTIC WATERS. THIS WILL ALLOW FOR SOME DRIER AIR TO WORK INTO SOUTH FLORIDA FROM THE NORTH EARLY NEXT WEEK...BEFORE MOISTURE RETURNS TO THE AREA FOR MIDDLE OF NEXT WEEK. THEREFORE...THE POPS FOR EARLY NEXT WEEK HAVE BEEN LOWER TO SLIGHT CHANCE OVER MOST OF SOUTH FLORIDA EXCEPT LOW END CHANCE OVER THE WESTERN AREAS. FOR MIDDLE OF NEXT WEEK...THE POPS WILL REMAIN IN THE CHANCE CAT OVER SOUTH FLORIDA. AVIATION... A WEAK TROUGH IS TRYING TO MAKES ITS WAY INTO SOUTH FLORIDA THIS AFTERNOON. THIS SHOULD ACT TO ENHANCE CONVECTION IN THE WESTERN HALF OF THE AREA. THE SEA BREEZE WILL KEEP THE EAST COAST CLEAR OF MOST CONVECTION, ALTHOUGH AN ISOLATED SHOWERS MAY STILL TRY TO FORM. GIVEN THIS, HAVE KEPT ANY SHRA/TSRA OUT OF THE EASTERN SITES THIS AFTERNOON. FOR KAPF, HAVE DELAYED VCTS FOR A FEW HOURS AS THE MODELS INDICATE IT WILL BE MORE TOWARDS THE MID AFTERNOON BEFORE CONVECTION AFFECTS NAPLES. HOWEVER, THIS COULD BE OFF A LITTLE, SO VCTS MAY NEED TO ADDED, OR EVEN DELAYED SOME, BASED ON DEVELOPMENT. WINDS WILL BE GENERALLY EASTERLY THIS AFTERNOON, WITH THE EXCEPTION OF KAPF, WHERE THE GULF BREEZE IS EXPECTED TO JUST MAKE IT PAST THE AIRPORT. TONIGHT, WINDS WILL LIGHTEN AND GO VARIABLE IN MANY LOCATIONS. THEY WILL ONCE AGAIN BECOME EASTERLY TOMORROW BETWEEN 5 AND 10 KTS. MARINE... THE WINDS WILL REMAIN FROM THE EAST NORTHEAST AT 10 KNOTS OR LESS THIS WEEKEND INTO EARLY NEXT WEEK OVER ALL OF SOUTH FLORIDA WATERS. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS WILL BE GOOD OVER ALL OF SOUTH FLORIDA WATERS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 89 77 88 77 / 40 20 20 10 FORT LAUDERDALE 89 79 89 79 / 40 20 20 10 MIAMI 90 78 89 78 / 50 20 20 10 NAPLES 91 74 91 74 / 50 30 30 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...23/SK AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
142 AM EDT SAT SEP 7 2013 .SYNOPSIS... A WEAK COLD FRONT WILL CONTINUE TO PUSH SOUTH OF THE AREA THIS EVENING WITH HIGH PRESSURE BUILDING FROM THE NORTH AND EXTENDING ACROSS THE AREA THROUGH THIS WEEKEND. A BACKDOOR COLD FRONT WILL APPROACH FROM THE NORTH SUNDAY AND BECOME STATIONARY NEAR OR JUST NORTH OF THE AREA MONDAY BEFORE DISSIPATING. HIGH PRESSURE WILL THEN PREVAIL THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A HIGHLY AMPLIFIED AND DEEP LAYERED ANTICYCLONE WILL REMAIN POSITIONED IN THE CENTRAL PLAINS/ROCKIES...AS A LOW AMPLITUDE SHORT WAVE DROPS SE THROUGH THE MEAN LONG WAVE TROUGH ALONG THE EASTERN SEABOARD. AT THE SURFACE AN ELONGATED REGION OF HIGH PRESSURE TO THE NORTH WILL CONTINUE TO BUILD INTO THE REGION...BRINGING WITH IT CONSIDERABLE DRY AIR ABOVE THE FIRST MILE OR SO OF THE TROPOSPHERE. EARLY MORNING RADAR IMAGERY DEPICTS CONVECTION SHIFTING SOUTHWARD JUST OFF THE SOUTH CAROLINA COAST DUE TO JUST ENOUGH LOW LEVEL MOISTURE ALONG WITH SOME ISENTROPIC LIFT ON THE 295K AND 300K SURFACES. WHILE TRAJECTORIES GENERALLY SUGGEST THAT THEY WILL REMAIN OVER THE ATLANTIC WHERE WHAT LITTLE LOW LEVEL CONVERGENCE AND LIFT WILL BE FOUND...SOME OF THE HIGHER RESOLUTION MESOSCALE MODELS SUCH AS THE HRRR SHOW SOME JUST BRUSHING COASTAL AREAS. AS A RESULT...HAVE ADDED MENTION OF A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR IMMEDIATE COASTAL AREAS THROUGH DAYBREAK. OTHER THAN SOME STRATOCUMULUS OVER COASTAL AREAS...LITTLE CLOUD COVER AND MOSTLY CALM WINDS INLAND WILL CONTINUE TO PROMOTE DECENT RADIATIONAL COOLING. BUT GIVEN THAT GEOSTROPHIC WINDS DO HOLD AROUND 10-15 KT WE WON/T GO TOO LOW...WITH MINIMUM TEMPS GENERALLY CLOSE TO SEASONAL LEVELS. 66-70 WEILL BE COMMON INLAND FROM US-17...WITH LOWER AND MIDDLE 70S CLOSER TO THE COAST WHERE A LIGHT NE AND EAST WIND WILL EXIST. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... SATURDAY THROUGH MONDAY...PRONOUNCED LONGWAVE TROUGHING WILL DOMINATE MUCH OF THE EASTERN U.S. THIS WEEKEND BEFORE LIFTING OUT EARLY NEXT WEEK. AT THE SURFACE...DRY SURFACE HIGH PRESSURE WILL EXTEND SOUTH ACROSS THE AREA. FORECAST SOUNDINGS INDICATE ONLY SHALLOW LOW-LEVEL MOISTURE WILL BE PRESENT SATURDAY...WITH THE DEPTH OF THE BEST LOW-LEVEL MOISTURE INCREASING SUNDAY AND MONDAY AS THE LOW-LEVEL FLOW BECOMES MORE ONSHORE. THIS WILL RESULT IN VERY SMALL PROBABILITIES FOR MEASURABLE RAINFALL THROUGH EARLY NEXT WEEK. SATURDAY LOOKS THE DRIEST WITH NO ACTIVITY...BUT ISOLATED SHOWERS/TSTMS WILL BE POSSIBLE ACROSS MAINLY SOUTH COASTAL SOUTH CAROLINA WITH THE SEA BREEZE SUNDAY. THE BACKDOOR FRONT WILL DROP SOUTH AND BECOME STATIONARY NEAR OR JUST NORTH OF THE AREA MONDAY MORNING...THUS ITS PROXIMITY COUPLED WITH THE AFTERNOON SEA BREEZE NECESSITIES KEEPING SLIGHT CHANCE POPS IN PLACE FOR ALL AREAS MONDAY...ALTHOUGH THE MAJORITY OF THE MODELS KEEP CONDITIONS DRY. THE ONLY EXCEPTION IS THE GFS WHICH SHOWS QUITE A BIT OF ACTIVITY FORMING ACROSS MAINLY SOUTHEAST SOUTH CAROLINA. THIS SOLUTION IS DISCOUNTED FOR NOW. TEMPERATURES WILL BE SEASONABLE THROUGH THE PERIOD WITH HIGHS IN THE UPPER 80S TO LOWER 90S WITH LOWS UPPER 60S TO MID 70S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... GOOD MODEL AGREEMENT THIS PERIOD WITH HIGH PRESSURE PREVAILING INTO THURSDAY BEFORE ANOTHER WEAK COLD FRONT PUSHING INTO THE AREA FRIDAY. FAIRLY TYPICAL SUMMERTIME PATTERN EXPECTED WITH MOSTLY ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS EACH AFTERNOON THROUGH THURSDAY. RAIN CHANCES SHOULD INCREASE A BIT FRIDAY WITH THE FRONT IN THE VICINITY. TEMPERATURES SHOULD BE NEAR OR SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH 06Z SUNDAY. EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER THAN 30 PERCENT CONFIDENCE AT THIS TIME. && .MARINE... TONIGHT...HIGH PRESSURE WILL CONTINUE TO NUDGE FURTHER SOUTH AND SW. THERE IS ENOUGH OF A PRESSURE GRADIENT TO KEEP EAST AND NE WINDS UP NEAR 10 OR 15 KT...BEFORE THEY BACK MORE NORTHERLY WITH LAND BREEZE INFLUENCES LATE. SEAS WON/T CHANGE MUCH,,,HOLDING AROUND 2 OR 3 FT...A MIX OF SMALL SWELLS AND WIND DRIVEN ENERGY. SATURDAY THROUGH MONDAY...A STEADY NORTHEAST FLOW WILL DOMINATE SATURDAY WITH WINDS AROUND 10 KT...POSSIBLY A BIT HIGHER ALONG THE LAND/SEA INTERACT WITH THE SEA BREEZE. WINDS ARE EXPECTED TO BECOME MORE ONSHORE SUNDAY AND MONDAY AS THE FLOW-LEVEL FLOW RESPONDS TO HIGH PRESSURE SHIFTING OFFSHORE. BOTH WINDS AND SEAS LOOK TO REMAIN WELL BELOW SMALL CRAFT ADVISORY CRITERIA. TUESDAY AND WEDNESDAY...NO SIGNIFICANT CONCERNS THIS PERIOD. WINDS MOSTLY 15 KT OR LESS WITH SEAS GENERALLY 3 FT OR LESS. RIP CURRENTS...WW4 OUTPUT FORECASTS AN UNDERLYING 2 FOOT SWELL DEVELOPING TONIGHT AND PERSISTING INTO SATURDAY WITH PERIODS INCREASING TO ABOUT 9 SECONDS. MODEST NORTHEAST WINDS COUPLED WITH THIS INCREASING SWELL AND INCREASING LUNAR INFLUENCES WILL PRODUCE A BORDERLINE MODERATE RISK FOR THE GEORGIA BEACHES SATURDAY. OPTED TO CAP THE RISK AT A HIGH-END LOW RISK FOR NOW GIVEN ITS AFTER THE MAIN BEACH SEASON...BUT THIS COULD EASILY BE UPPED TO A MODERATE RISK WITH LATER FORECASTS. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...JAQ SHORT TERM...ST LONG TERM...RJB AVIATION...JAQ/ST MARINE...
AREA FORECAST DISCUSSION
NWS BUFFALO NY
435 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW SPRINKLES NORTH OF THE THRU-WAY. AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY. HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM BUFFALO TO NIAGARA FALLS. A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION. THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW TO MID 60S FOR MUCH OF THE REGION. SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT. ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT. MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A COLD FRONT IN THE WESTERN GREAT LAKES. ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS. THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S.. AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE JULY THAN MID-SEPTEMBER. IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000 J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND WEDNESDAY NIGHT. THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE AVERAGE. THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK BREEZE. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THIS MORNING WITH MAINLY MID AND HIGH CLOUDS. THE EXCEPTION IS AT JHW...WHERE VSBY WILL VARY IN GROUND FOG...WHICH SHOULD DISSIPATE AROUND 12Z. AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT. OUTLOOK... SUNDAY...MVFR CIGS LIFTING BY AFTERNOON. SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR. WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS. && .MARINE... THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT AND MONDAY...AS HIGH PRESSURE BUILDS IN. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR LEZ020-041. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
352 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW SPRINKLES NORTH OF THE THRU-WAY. AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY. HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM BUFFALO TO NIAGARA FALLS. A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION. THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW TO MID 60S FOR MUCH OF THE REGION. SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT. ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT. MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A COLD FRONT IN THE WESTERN GREAT LAKES. ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS. THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S.. AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE JULY THAN MID-SEPTEMBER. IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000 J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND WEDNESDAY NIGHT. THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE AVERAGE. THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK BREEZE. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS WILL PREVAIL THROUGH THIS MORNING WITH ONLY MID- HIGH CLOUDS. AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT. OUTLOOK... SUNDAY...MVFR CIGS LIFTING BY AFTERNOON. SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR. WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS. && .MARINE... THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT AND MONDAY...AS HIGH PRESSURE BUILDS IN. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR LEZ020-041. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
153 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY. A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY... FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK. TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING HUMIDITY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS RUNNING IN THE M40S ACROSS MOST OF THE REGION. THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY TO MOSTLY SUNNY SKIES. A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS. HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR 80F THROUGHOUT THE LOWER SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/ DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST ACROSS THE SE. LOWS WILL BE NOTICEABLY MILDER...ONLY DROPPING INTO THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT. DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING THE MORNING. ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY INT HE 40S ELSEWHERE. MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST. A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE US. TEMPS WILL AGAIN MOVE ABOVE NORMAL. THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE CFRONT. DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY SKIES SHOULD PREVAIL ELSEWHERE. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... SFC HIGH PRES OVR PA AND ADJ STATES TDY WILL YIELD TO A COLD FRONT PUSHING SEWD FROM THE LWR GRT LKS. THE FRONT WILL MOVE NW-SE THRU THE AIRSPACE FROM LATE TONIGHT THRU THE DAYLIGHT HOURS ON SUNDAY. WDLY SCT LGT SHOWERS/SPRINKLES SHOULD ACCOMPANY THE COLD FRONT...FOLLOWED BY A BAND OF POST-FRONTAL LOW END VFR TO MVFR CIGS. SFC WNDS WILL SHIFT FROM WSW TO NNW BEHIND THE FRONT. HIGH PRES RETURNS VFR CONDS FOR MONDAY...BEFORE AN INCREASINGLY MOIST SLY FLOW AND ASSOCD WARM FRONT THREATENS MVFR CIGS AND ISOLD CONVECTION FOR TUES. A COLD FRONT PUSHING SEWD FROM THE GREAT LAKES WILL LKLY BE A FOCUS FOR SCT SHOWERS/TSTMS THRU THE MIDDLE OF NEXT WEEK. OUTLOOK... SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA. MON...VFR. NO SIG WX. TUE/WED...AM FOG PSBL. VFR WITH ISOLD-SCT TSTM IMPACTS PSBL. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...STEINBUGL LONG TERM...RXR AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
407 AM CDT SAT SEP 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT SAT SEP 7 2013 TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000 J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM 700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO BECOME ALL THAT ORGANIZED OR SEVERE. BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY. QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT. HAVE RAISED SKY COVER IN THE EAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 406 AM CDT SAT SEP 7 2013 EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA. THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST. SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70. LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14 CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30 POP IN THAT REGION. MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST. CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT. INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS. MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION PARALLEL TO THE FRONT. BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT. LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH OF TEMPERATURES THE FOLLOWING WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1054 PM CDT FRI SEP 6 2013 MOSTLY VFR THROUGH 08/06Z. AN EXCEPTION MAY BE PATCHY RADIATION FOG 09Z-14Z IN SOUTHEAST PART OF THE AREA AS FLOW BECOMES LIGHT AND BEST LOW LEVEL MOISTURE LINGERS...SO HAVE GONE FOR BRIEF MVFR AT KSUX. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM... LONG TERM...CHENARD AVIATION...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
323 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST ON MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 210 AM EDT SATURDAY... GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY. OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW 80S WITH MAINLY 70S ELSW. NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT. HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM EDT SATURDAY... A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND. GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST. TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON MONDAY. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 345 PM EDT FRIDAY... HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER. BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... AS OF 1250 AM EDT SATURDAY... OVERALL STILL LOOKING AT ISSUES WITH EITHER FOG OR STRATOCU/STRATUS ACROSS THE AREA LATE TONIGHT. THE LATEST NAM IS AGGRESSIVE SHOWING REFORMATION OF LOWER CIGS ACROSS MOST OF THE AREA UNDER AN INVERSION. MEANWHILE THE GFS/CMC ARE CLEARING THINGS OUT ALTHOUGH THE CMC ACTUALLY SHOWS REDEVELOPMENT WEST OF THE BLUE RIDGE AND INTO THE ALLEGHANYS DURING THE EARLY MORNING HOURS. THUS HAVE CONTINUED TO LEAN THE AVIATION FORECAST MORE TOWARD THE CLOUDIER NAM IN THE WEST AND A BLEND ELSW THROUGH EARLY SAT MORNING. THUS MEDIUM TO HIGH CONFIDENCE THAT ALL TAF SITES WILL BE GETTING AT LEAST A BKN CIG OF VFR AT ROA/LYH/DAN BETWEEN 2AM AND 6AM. MEANWHILE BLF/BCB/LWB WILL BE DEALING WITH AN MVFR CIG FORMING GIVEN THAT ELEVATIONS ARE HIGHER ALTHOUGH LWB MAY STAY CLEAR LONGER BEFORE FOG FORMS WITH JUST SOME HIGH CLOUDS AROUND. POTENTIAL SE UPSLOPE FLOW MAY CAUSE CIG TO DROP UNDER 1KFT AT TIMES IN THE MORNING ALONG THE BLUE RIDGE SO HAVE A TEMPO GROUP TO COVER THIS. STILL CANNOT RULE OUT DENSE FOG AT LWB BUT MAY BE ENOUGH MIXING TO CLEAR THEM OUT FASTER SAT MORNING INTO AN MVFR CIG...WHILE BCB REMAINS AT THE TOP END OF MVFR. ALL SITES WILL BE VFR BY LATE MORNING/MIDDAY SAT AS WINDS SHIFT TO THE WEST AND SW. SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH TO ALONG THE MID ATLANTIC COAST BY SATURDAY EVENING PROVIDING MAINLY CLEAR SKIES OUTSIDE OF HIGH CLOUDS. ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE AREA LATE IN THE WEEKEND...THEN STALL AND EVENTUALLY WASH OUT JUST TO OUR SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST BUILDS EAST TOWARD THE MID-ATLANTIC. EXPECT A RETURN TO MORE TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY- DRIVEN SHRA/TSRA ON SUNDAY WHEN THE FRONT MOVES SOUTH THROUGH THE REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE OUTSIDE MORNING FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS THE AIR MASS ACROSS THE REGION BECOMES INCREASINGLY TROPICAL WITH DEWPOINTS IN THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS POINT...NO WIDESPREAD EXTENDED DURATION OF POOR AVIATION CONDITIONS ARE EXPECTED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WERT NEAR TERM...JH SHORT TERM...DS LONG TERM...NF AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
238 AM PDT Sat Sep 7 2013 .SYNOPSIS... The low pressure system responsible for showers and thunderstorms the last couple of days will bring another round of wet weather to the Cascades and northern mountains again today. Sunday will be a drier day for most of the Inland Northwest with showers limited to mainly the Idaho Panhandle. Dry, summer-like weather will return Monday through Thursday as a strong high pressure ridge develops over the region. && .DISCUSSION... Today through Sunday...A large closed low near Republic will be nearly stationary today...before moving east towards the North Idaho Panhandle tonight...and then exiting the area into Montana on Sunday. For this morning main focus is the wrap around band near the North Washington Cascades on the back side of the low where a steady light rain has been falling around Stehekin. The HRRR has been consistent with a large area of light rain over far southwest BC dropping southeast into Mazama, Stehekin early this morning spreading east into Chelan...Brewster...and the Waterville Plateau during the mid morning hours. While this rain will be light...additional rain on saturated ground where mud slides have already occurred may result in additional slides although confidence is marginal of this. Given uncertainty will continue with current Flash Flood Watches for the East Slopes of the Cascades and Wenatchee area. This wrap around band will swing northeast towards Colville and Chewelah during the early afternoon. Cloud cover associated with this may limit thunderstorm chances this afternoon over the Northeast Washington Mountains and Idaho Panhandle. West of this band over the Okanogan Highlands, Okanogan Valley, and East Slopes of the Cascades a better potential for isolated thunderstorms exists with sun breaks more likely to develop. Less instability will exist from Spokane southward due to further proximity from low with only isolated showers at most expected for today. Cloud cover today will keep temperatures below average over all of the region. Tonight showers will decrease with the loss of daytime heating and be confined mainly to northeast Washington and North Idaho with the closed low tracking across this region. Then on Sunday showers will continue in these areas although with the low departing out of the area showers will only be scattered in nature with a slight chance of afternoon thunderstorms. A short wave ridge will approach the Cascades late Sunday afternoon which will allow for more pronounced warming over Central Washington with less cloud cover and showers compared to today. JW Sunday Night: The exiting upper trough may yield some early evening showers over the Idaho Panhandle, but 500mb temperatures will be warming and instability profiles don`t suggest more than isolated thunder potential prior to sunset. Monday through Friday: Summer will return next week with temperatures well above average. There is good model agreement through about Thursday that a high amplitude high pressure ridge will develop over the Pacific Northwest. Wednesday and Thursday look to be the warmest days of the week with 850mb temperatures in the 22-24C range. Many lowland areas will be in the upper 80s to lower 90s which is about 10 degrees above average. Forecast confidence diminished markedly Friday into next weekend. There is very little agreement between the 00z models and run-to- run consistency has not been good either. A cooling trend into next weekend is probable, but the timing/track/intensity of an incoming Pacific trough (and subsequent ridge breakdown) is highly uncertain at this time. /GKoch && .AVIATION... 06Z TAFS: The pesky and very slow moving low pressure system will continue to produce scattered precipitation through Saturday night across the forecast area. While a mid level deck is expected around the region there should be a break in the precipitation late tonight...before picking up Saturday afternoon again. At this time anything below vfr conditions is not expected...although some fog will be possible early Saturday morning for the KGEG-KCOE corridor. /EK && .PRELIMINARY POINT TEMPS/POPS... Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0 Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0 Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0 Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0 Colville 70 50 81 51 85 51 / 70 30 20 10 0 0 Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10 Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10 Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0 Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0 Omak 74 54 83 56 86 57 / 70 30 10 10 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flash Flood Watch through this evening for East Slopes Northern Cascades-Wenatchee Area. && $$
AREA FORECAST DISCUSSION...RETRANSMISSION
NWS SAN DIEGO CA
845 AM PDT SAT SEP 7 2013 .SYNOPSIS... CONTINUED VERY WARM AND HUMID TODAY WITH SCATTERED AFTERNOON THUNDERSTORMS AGAIN OVER THE MOUNTAINS. THE THUNDERSTORMS WILL LIKELY PRODUCE TORRENTIAL DOWNPOURS WITH LOCAL FLASH FLOODING POSSIBLE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST COAST EARLY NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING THUNDERSTORM CHANCES OVER THE MOUNTAINS AND DESERTS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... SKIES WERE MOSTLY CLEAR EARLY THIS MORNING OVER THE CWA. HOWEVER...WATER VAPOR IMAGERY INDICATED A SHARP MOISTURE BOUNDARY IN THE ATMOSPHERE ALONG THE FOOTHILLS. THE 12Z MIRAMAR SOUNDING HAD A SFC BASED INVERSION WITH LIGHT WINDS UP THROUGH 25K FT. PW HAD DECREASED TO 1.43 INCHES...BUT GPS SOUNDERS AND SFC DEWPOINT INCREASES ACROSS THE DESERTS SUPPORT PWS CLOSER TO TWO INCHES. SFC PRESSURE GRADIENTS AT 14Z ARE WEAK OFFSHORE. CONTINUED VERY WARM TO HOT AND HUMID AGAIN TODAY. MAIN CONCERN AGAIN WILL BE THE THUNDERSTORM AND FLASH FLOOD THREAT OVER THE MTNS/ DESERTS. HIGH PW VALUES OVER EASTERN PORTIONS OF THE AREA SUPPORT A FLASH FLOOD WATCH THIS AFTERNOON AND EVENING. THE 12Z MIRAMAR SOUNDING LOOKS A BIT MORE STABLE...BUT IT IS IN A DIFFERENT AIRMASS THAN THE DESERTS. THE LOCAL WRF/HRRR/NAM12 ALL DEVELOP THUNDERSTORMS OVER THE MTNS THIS AFTERNOON. THE 12Z HRRR ALSO SHOWS ISOLATED CONVECTION OVER THE INLAND EMPIRE WHICH IS SUPPORTED BY HIGHER SFC DEWPOINTS AND EASTERLY FLOW THROUGH THE BANNING PASS THIS MORNING. ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT HAVE THE DEEP LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS...SO IT IS NOT INCLUDED IN THE FLASH FLOOD WATCH. GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/ THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME... THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST... DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK. REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS CRITICAL. BOTH THE 00Z ECMWF/06Z GFS SHOW THE AXIS E OF THE CWA ON MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR EAST...HOWEVER THE 00Z ECMWF RUN PULLS IT BACK INTO THE UPPER LOW CIRCULATION WHICH RESULTS IN CONTINUED PRECIP CHANCES FOR THE ENTIRE CWA INTO MON. FOR NOW...FAVOR THE GFS MOISTURE FIELD/PCPN...KEEPING THE THREAT MORE TO THE EAST. LOOKING AHEAD TO THE END OF NEXT WEEK...00Z/06Z GLOBAL MODEL RUNS DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS WARMER. && .AVIATION... 071508Z...COAST/VALLEYS...DURING THE 1900-08/0300 UTC TIME-PERIOD...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS CLDS AOA 8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG REACHING KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING. OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING. MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS DURING THE 1800-08/0100 UTC TIME-PERIOD WITH BASES 7000-10000 FT MSL AND CB TOPS TO 40000 FT MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY RAIN...SMALL HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS. OTHERWISE...UNRESTRICTED VIS THROUGH SUNDAY MORNING. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS. PZ...NONE. && $$ PUBLIC...JAD AVIATION...HARRISON
AREA FORECAST DISCUSSION
NWS ALBANY NY
1025 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. THE SOUTHERLY FLOW AROUND THIS HIGH PRESSURE AREA WILL RESULT IN A MILDER DAY TODAY. A COLD FRONT WILL CROSS THE REGION LATE TONIGHT AND EARLY SUNDAY MORNING WITH THE CHANCE FOR SOME RAIN SHOWERS... FOLLOWED BY BREEZY AND COOLER CONDITIONS BEHIND IT FOR THE REST OF SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM EDT...CLOUD SHIELD CONTINUES TO ADVANCE EASTWARD WITH UPSTREAM REGIONAL RADARS REVEALING THE LEADING EDGE OF THE RAINFALL ACROSS LAKE ONTARIO. PER EXTRAPOLATION...THE WESTERN DACKS WOULD SEE HIGHER POPS TOWARD OR SHORTLY AFTER THE NOON HOUR THEN SPREAD INTO EASTERN NY DURING THE MID AND LATE AFTERNOON. THIS TOO IS IN AGREEMENT WITH THE RATHER AGGRESSIVE HRRR REFLECTIVITY FORECAST. PER THESE OBSERVATIONS...HAVE LOWERED AFTERNOON HIGHS A COUPLE OF DEGREES AND MODIFIED PRECIP/POP POTENTIAL PER EXTRAPOLATION TRENDS. THE MAIN LIFT AND UPPER SUPPORT ARRIVE AFTER SUNSET WHEN THOSE POPS INCREASE PER THE PREVIOUS FORECAST. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... THE COLD FRONT WILL CROSS THE REGION WITHIN A FEW HOURS EITHER SIDE OF SUNRISE ON SUNDAY. AHEAD OF THE FRONT HAVE INCREASED POPS TO BETWEEN 40 AND 50 PERCENT. DRIER AIR RUSHES IN VERY QUICKLY BEHIND THE FRONT AND THE FLOW BECOME ANTICYCLONIC BY EARLY AFTERNOON. THIS WILL MINIMIZE THE CONTINUATION OF ANY SHOWERS IN THE COLD ADVECTION BEHIND THE FRONT AND HAVE FORECAST THE WEATHER TO BECOME PCPN FREE ACROSS THE ENTIRE REGION FROM LATE MORNING AND BEHIND. AS ANOTHER SPRAWLING COOL CANADIAN HIGH PRESSURE SYSTEM WILL BUILDS INTO THE REGION SUNDAY AFTERNOON AND NIGHT AND THEN MOVES OFFSHORE ON MONDAY...EXPECT CLEAR TO MAINLY CLEAR SKIES WITH COOL TEMPS SUNDAY AFTN THROUGH MONDAY. TEMPERATURE WISE...LOWS SATURDAY NIGHT WILL BE IN THE 50S. HIGHS SUNDAY WILL RANGE FROM THE UPPER 50S OVER THE ADIRONDACKS WHERE THE COOLER AIR MOVES IN FIRST...TO THE LOW OR MID 70S FROM THE MID HUDSON VALLEY TO NORTHWEST CONNECTICUT. LOWS SUNDAY NIGHT WILL BE IN THE 30S TO LOWER 40S AND PATCHY OR AREAS OF FROST HAS BEEN FORECAST IN COLDER AREAS AND ALSO BEEN HIGHLIGHTED IN THE HWOALY PRODUCT. HIGHS MONDAY WILL BE IN THE MID 60S TO MID 70S. && .LONG TERM /MONDAY THROUGH FRIDAY/... ONCE AGAIN PRETTY GOOD AGREEMENT AMONGST THE LONGER RANGE MODELS ALTHOUGH THE CMC ATTEMPTS TO BRING A TROPICAL SYSTEM NEAR OUR REGION BY NEXT WEEKEND. SINCE THE OTHER MODELS DO NOT HAVE SUCH A FEATURE...WE HAVE DISCARDED THAT MODEL. MONDAY NIGHT...IT LOOKS AS A RATHER STRONG WARM FRONT WILL WORK ACROSS THE REGION MONDAY NIGHT OR EARLY TUESDAY. THE EUROPEAN MODELS (ECMWF) CONTINUES TO INDICATE A PRETTY GOOD MCS ASSOCIATED WITH THIS FEATURE...LESS SO BY THE GFS. THE ECMWF STILL INDICATED A 30-40KT H850 JET THAT COULD TRANSPORT A SLUG OF ELEVATED CONVECTION INTO THE ADIRONDACKS. FOR NOW...WE HAVE INTRODUCED 30 POPS ACROSS OUR NORTHWESTERN ZONES WHERE IT APPEARS THAT GREATEST QPF COULD TAKE PLACE...SLIGHT POPS ELSEWHERE. OVERNIGHT LOWS LOOK TO BE IN THE 50S FROM ALBANY SOUTHWARD...40S NORTH. BY TUESDAY RISING HEIGHTS AND A SOUTHWESTERLY FLOW LOOKS TO USHER IN SOME MUCH WARMER AND HUMID AIR. DEPENDING ON HOW HOW FAST THE CLOUDS LIFT OUT WILL ULTIMATELY DETERMINE HOW WARM WE GET. H850 TEMPERATURES LOOK TO JUMP WELL INTO THE TEENS. WE FIGURE THE CLOUDS WILL BE SOMEWHAT SLOW TO BURN OFF SO WENT ON THE LOWER END OF MIXING...HIGHS 75 TO 80. WE CARRY ONLY SLIGHT CHANCES OF SHOWERS THROUGH WEDNESDAY MORNING. TUESDAY NIGHT LOOKS RATHER MUGGY BY SEPTEMBER STANDARDS WITH LOWS GENERALLY IN THE 60S. WEDNESDAY LOOKS UNSEASONABLY WARM. H850 TEMPERATURES LOOK TO CREST NEAR +18C VIA THE 00Z GFS/+20C ON THE ECMWF! WE WENT ON THE HIGH SIDE OF GUIDANCE WITH HIGHS WELL INTO THE 80S...PUSHING NEAR 90 DEGREES IN THE MID HUDSON VALLEY. DEWPOINTS LOOK TO RISE WELL INTO THE 60S TO NEAR 70 GIVING THOSE AIR CONDITIONER AT LEAST ONE MORE WORKOUT FOR THE YEAR. BY LATE WEDNESDAY...THE AIR LOOKS TO BECOME QUITE UNSTABLE AS THE FIRST IN A SERIES OF COLD FRONTS (OR PRE-FRONTAL TROUGH) NEARS OUR REGION. WILL CARRY 30/40 POPS LATE AFTERNOON INTO WEDNESDAY NIGHT. LOWS WEDNESDAY WILL REMAIN WARM...60S TO NEAR 70. THURSDAY...IT LOOKS AS NOT ONE BUT TWO FRONTS WILL PASS THROUGH...LINGERING INTO THE EVENING. WHILE IT WILL LIKELY NOT BE SHOWERING OR STORMING THE ENTIRE TIME...AT THIS POINT...IT IS HARD TO TIME WHEN AND IF CONVECTION WOULD OCCUR...BUT THE THREAT CERTAINLY LOOKS THERE...WITH THE GFS INDICATE SURFACE BASED CAPES WELL OVER 1000 JOULES. WILL CARRY 30/40 POPS THROUGH THIS PERIOD. BOTH THE GFS AND ECMWF BOTH INDICATE THE MAJOR COLD FRONT WILL SWEEP THROUGH THE REGION THURSDAY NIGHT WITH PERHAPS A LINGERING SHOWER OR TWO. FRIDAY...ANOTHER MUCH COOLER CANADIAN AIRMASS LOOKS TO INVADE. WILL HAVE SLIGHT POPS ACROSS OUR HIGHER TERRAIN WHERE UPSLOPE AND LINGERING COLD AIR ADVECTION PROCESSES COULD TRIGGER AN INSTABILITY SHOWER WHILE VALLEY AREAS LOOK DRY. IT WILL BE QUITE BREEZY. HIGHS WILL RANGE FROM ABOUT 70 IN THE HUDSON VALLEY...TO ONLY 60S ELSEWHERE. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... KPSF WENT BRIEFLY TO IFR EARLIER THIS MORNING. WHILE KALB DID NOT...WE HAD IFR CLOUDS AND SOME IFR FOG AT OUR OFFICE THAT WERE LIKELY BELOW 1000 FEET. FOR NOW WE DECIDED NOT TO INCLUDE THE 200 FOOT BROKEN CEILING AT KALB AND 2SM BR IN A ONE HOUR TEMPO THROUGH 12Z. ANY AND ALL FOG WILL BURN OFF BY AROUND 13Z....LEAVING US WITH A VFR DAY. HIGH CLOUDS WILL GENERALLY INCREASE AND SO WILL A SOUTHERLY BREEZE....TO THE TUNE AROUND 10KTS AT KALB. ANY AND ALL FOG WILL DISSIPATE BY AROUND 14Z. VFR CONDITIONS WILL PREVAIL DURING THE DAY SATURDAY WITH A GENERAL INCREASE IN HIGH CLOUDS AND A SOUTHERLY BREEZE...APPROACHING 10KTS BY MIDDAY. BY LATE IN THE DAY...A FEW SHOWERS...AHEAD OF THE NEXT COLD FRONT COULD IMPACT THE TERMINALS PERHAPS A BRIEF REDUCTION IN VISIBILITY AND LOWERING OF CIGS. FOR NOW...CONTINUED WITH VCSH BY LATE IN THE AFTERNOON...EXCEPT NOT UNTIL EVENING AT KPOU. OUTLOOK... SUNDAY...LOW OPERATIONAL IMPACT. BREEZY. SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. TUESDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. && .FIRE WEATHER... NO FIRE WEATHER ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS. RH VALUES WILL DROP TO BETWEEN 35 AND 50 PERCENT THIS AFTERNOON WITH SOUTH TO SOUTHWEST WINDS AROUND 5 TO 10 MPH. RH VALUES WILL ONCE AGAIN RETURN TO NEAR 100 PERCENT TONIGHT WITH A GOOD CHANCE OF RAIN SHOWERS. && .HYDROLOGY... NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH TUESDAY. RIVER LEVELS WILL CONTINUE TO RECEDE OR HOLD STEADY OVER THE NEXT FEW DAYS. HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. A COLD FRONT WILL CROSS THE REGION LATE TONIGHT AND EARLY SUNDAY MORNING WITH THE CHANCE FOR SOME RAIN SHOWERS...FOLLOWED BY BREEZY AND COOLER CONDITIONS BEHIND IT FOR THE REST OF SUNDAY. AS ANOTHER LARGE HIGH PRESSURE SYSTEM SETTLES OVER THE REGION...THERE WILL BE DRY WEATHER THROUGH TUESDAY. THE QPF OVER THE WEEKEND WILL BE FAIRLY LIGHT. MOST AREAS OUTSIDE THE ADIRONDACKS WILL ONLY SEE A TENTH OR TWO OF AN INCH AT MOST...WITH UP TO A THIRD OF AN INCH ACROSS THE ADIRONDACKS. THIS RAINFALL WILL HAVE LITTLE IMPACT ON AREA RIVERS AND STREAMS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...GJM NEAR TERM...GJM/BGM SHORT TERM...GJM LONG TERM...HWJIV AVIATION...HWJIV FIRE WEATHER...GJM HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS POCATELLO ID
906 AM MDT SAT SEP 7 2013 .UPDATE...STRONG MOISTURE GRADIENT LAYING ACROSS EAST IDAHO TODAY AS UPPER LOW CONTINUES TO DRIFT EAST ALONG THE PACNW/CANADIAN BORDER. DEEPEST MOISTURE IN PLACE OVER THE EASTERN HALF OF THE FORECAST AREA MAINLY SNAKE PLAIN AND HIGHLANDS SOUTH/EAST. CENTRAL MOUNTAINS MUCH DRIER BUT CLOSER TO BEST DYNAMICS ASSOCIATED WITH UPPER LOW. HRRR THIS MORNING PAINTING WIDE SWATH OF MOISTURE MOVING THROUGH THE SOUTH/EAST HIGHLANDS LATE THIS MORNING INTO EARLY THIS AFTERNOON. NAM/LOCAL WRF DEVELOPS BETTER SWATH OF CONVECTION LATER THIS AFTERNOON. CLOUD COVER EARLY THIS MORNING MAY ALSO HAVE A SMALL IMPACT ON INSTABILITY. HAVE MADE A FEW TWEAKS TO SKY/POP/WX GRIDS FOR TODAY...HOLDING ON TO HIGH CHANCE POPS IN THE DEEPEST MOISTURE BUT RETAINING ISOLATED POPS OVER PORTIONS OF THE CENTRAL MOUNTAINS. DMH && .PREV DISCUSSION... /ISSUED 319 AM MDT SAT SEP 7 2013/ SHORT TERM...TODAY THROUGH MONDAY. UPPER LOW IN WASHINGTON STATE WILL CONTINUE TO PUSH VERY SLOWLY EAST THROUGH MONDAY. MONSOONAL MOISTURE CONTINUES TO BE OVER THE REGION ON THE SOUTHWESTERLY FLOW ALOFT AND EXPECT CONTINUED ISOLATED TO SCATTERED THUNDERSTORMS TODAY WITH THE BEST ACTIVITY AGAIN IN THE EASTERN AREAS. UPPER TROF FINALLY MOVES THROUGH SUNDAY AND ENOUGH DYNAMICS AND INSTABILITY TO CONTINUE WITH THE THREAT FOR THUNDERSTORMS BUT NOT AS WIDESPREAD AS TODAY. FLOW ALOFT TURNS NORTHWESTERLY MONDAY AND EXPECT DRY CONDITIONS ACROSS THE WHOLE REGION FINALLY. TEMPERATURES MONDAY SHOULD ALSO BE NEAR SEASONAL NORMALS AFTER THE EXTENDED PERIOD OF WELL ABOVE NORMAL CONDITIONS. EXPECT SOME BREEZY CONDITIONS SUNDAY WITH THE PASSAGE OF THE UPPER TROF AND SURFACE COLD FRONT. GK LONG TERM...TUESDAY THROUGH SATURDAY. UPPER RIDGE BUILDS IN TUESDAY AND EXPECT DRY CONDITIONS TUESDAY AND WEDNESDAY. FLOW AGAIN TURNS SOUTHERLY ALLOWING MOISTURE BACK INTO THE REGION AND HAVE A CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY THROUGH SATURDAY. GK AVIATION...THE LATEST SATELLITE IMAGERY WAS SHOWING A LOW PRESSURE SYSTEM LIFTING NORTH INTO SRN BRITISH COLUMBIA AS SUB-TROPICAL MOISTURE CONTINUED TO ARC NORTH ACROSS SE IDAHO AND DRIER CONDITIONS OVERSPREAD THE SW. MODEL SOLUTIONS SHOW THE UPPER LOW SHIFTING EAST ALONG THE CANADIAN BORDER TODAY AND SUNDAY EFFECTIVELY SHUNTING THE SUB-TROPICAL FLOW FURTHER EAST INTO WYOMING SUNDAY. MAY STILL HAVE TO CONTEND WITH VCTS/TSRA REMARKS IN THE TERMINALS TODAY AND TO A LESSER EXTENT SUNDAY AS THE SUB-TROPICAL MOISTURE IS PUSHED FURTHER EAST...OTHERWISE VFR CONDITIONS SHOULD PREVAIL. HUSTON FIRE WEATHER...A LOW PRESSURE SYSTEM POSITIONED ALONG THE WASHINGTON/BRITISH COLUMBIA BORDER EARLY THIS MORNING WILL BEGIN TO MIGRATE EAST TODAY AND SUNDAY. SUB-TROPICAL MOISTURE STREAMING NORTH ACROSS THE GREAT BASIN WILL GET SHUNTED FURTHER EAST INTO WYOMING SUNDAY AND COLORADO BY MONDAY AS A FAIRLY DRY NW FLOW OVERSPREADS IDAHO IN THE WAKE OF THE EXITING LOW. WIND GUSTS WILL NOSE UP TOWARD WARNING LEVELS SUNDAY AFTERNOON WHILE MINIMUM HUMIDITY LEVELS FALL INTO THE UPPER TEENS ACROSS THE CNTRL MOUNTAINS AND ARCO DESERT REGIONS. FUELS STILL FAIRLY MOIST DUE TO RECENT MONSOONAL ACTIVITY THUS NO HIGHLIGHTS ARE WARRANTED AT THIS TIME. A RIDGE OF HIGH PRESSURE AND WARMER TEMPERATURES BUILD ACROSS THE REGION THROUGH MID-WEEK AS A SUB-TROPICAL DISTURBANCE LIFTS NORTH THROUGH MEXICO/ARIZONA. THE ADVANCING SUB-TROPICAL MOISTURE WILL LIKELY LIFT INTO SRN IDAHO THURSDAY/FRIDAY FOR YET ANOTHER ROUND OF HEAVY SHOWERS AND THUNDERSTORMS. HUSTON && .PIH WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
720 AM CDT SAT SEP 7 2013 .UPDATE... ISSUED AT 709 AM CDT SAT SEP 7 2013 FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW HUNDREDTHS. PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT SHOWERS CAN BE EXPECTED FOR THE MORNING. DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE EVENING HOURS. ..08.. && .SYNOPSIS... ISSUED AT 324 AM CDT SAT SEP 7 2013 06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH 50S OVER THE EASTERN GREAT LAKES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT SEP 7 2013 RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA. SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA. THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST. MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON. TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF THE AREA WILL REMAIN DRY TONIGHT. ..08.. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT SEP 7 2013 IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE. THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S. SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z. TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 709 AM CDT SAT SEP 7 2013 MAINLY VFR WX WILL BE SEEN THROUGH 00Z/08. A WEAK DISTURBANCE MOVING THROUGH IOWA/ILLINOIS WILL KEEP VCSH AT KMLI/KBRL THROUGH 15Z/07. DIURNAL SHRA/TSRA WILL BE POSSIBLE AFT 18Z/07 AND IF A TSRA IMPACTS A TAF SITE...A BRIEF PERIOD OF MVFR WX WILL BE POSSIBLE. A FRONT WILL MOVE THROUGH IOWA/ILLINOIS AFT 00Z/08 SHIFTING WINDS AROUND TO THE NORTHEAST. MVFR VSBYS MAY BE POSSIBLE AFT 03Z/08 DUE TO HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...08 SHORT TERM...08 LONG TERM...DLF AVIATION...08
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1058 AM EDT SAT SEP 7 2013 .UPDATE... ISSUED AT 1057 AM EDT SAT SEP 7 2013 TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS ASSOCIATED WITH THE FRONT SHOULD BE DONE. ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON. THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER 70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL BE OUT SHORTLY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 519 AM EDT SAT SEP 7 2013 GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST 24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR. THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z. EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/. LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 505 AM EDT SAT SEP 7 2013 IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST. FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7 DAY FCST. BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF... CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT 12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE GREAT LAKES. SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE... DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM. OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS... ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL INTO THE LWR 40S. MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN. THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI... NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON... ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR. RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF 30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON. BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE... SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA. HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE... NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER. WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS SAT SHOULD BE CLOSER TO NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 757 AM EDT SAT SEP 7 2013 PLENTY OF LOW LEVEL MOISTURE HAS RESULTED IN IFR-MVFR VIS AT SEVERAL UPSTREAM AND DOWNSTREAM LOCATIONS. HOWEVER CMX...IWD...AND SAW REMAINED MAINLY FOG FREE AS CLOUDS LINGERED AND SFC TEMPERATURES REMAINED A LITTLE TOO WARM. WILL CONTINUE TO TRACK THE EXITING COLD FRONT AND CONTINUED POTENTIAL FOR SCT-ISO SHOWERS AND TS THROUGH EARLY AFTERNOON. HAVE KEPT THE MENTION OF SHOWERS OR TS OUT OF ALL SITES /EXCLUDING VCTS AT CMX INITIALLY AS A CLUSTER OF TS PUSH ACROSS THE KEWEENAW PENINSULA/. WITH DRY HIGH PRESSURE SLOWLY PUSHING IN FROM THE NW THIS AFTERNOON EVENING...DO NOT EXPECT ANY FOG TO DEVELOP TONIGHT. EXPECT WINDS AROUND 10KTS OR LESS OVERNIGHT...UNDER A MOSTLY CLEAR SKY. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 519 AM EDT SAT SEP 7 2013 A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...SRF SHORT TERM...KF LONG TERM...ROLFSON AVIATION...KF MARINE...KF
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1043 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... RADAR IMAGERY SHOWING AN EXTENSIVE AREA OF STEADY RAIN AND A FEW EMBEDDED LIGHTNING STRIKES OVER SOUTHERN ONTARIO AND LAKE ONTARIO THIS MORNING. THIS AREA OF RAIN IS FASTER AND FARTHER SOUTH THAN ANY MODEL GUIDANCE...SO TIMING AND PLACEMENT OF RAIN HAS BEEN ADJUSTED FOR TODAY BY EXTRAPOLATION OF RECENT RADAR AND SATELLITE TRENDS. HAVE BROUGHT THE STEADIER RAIN INTO THE COUNTIES ALONG AND SOUTHEAST OF THE LAKE ONTARIO SHORE...WITH A FAIRLY SHARP CUTOFF TO LOWER CHANCE POPS ACROSS THE SOUTHERN PORTION OF THE AREA AND ALSO IN THE SAINT LAWRENCE VALLEY. WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE AREA OF STEADY RAIN OVER LAKE ONTARIO. WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES WILL STRUGGLE TO REACH 70 TODAY IN MANY AREAS. THE ONLY EXCEPTION WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY TIME WILL STILL BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN THE VALLEYS THERE. A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION. THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW TO MID 60S FOR MUCH OF THE REGION. SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT. ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT. MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A COLD FRONT IN THE WESTERN GREAT LAKES. ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS. THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S.. AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE JULY THAN MID-SEPTEMBER. IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000 J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND WEDNESDAY NIGHT. THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE AVERAGE. THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK BREEZE. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS GIVEN THE DRY LOW LEVELS NOTED ON THE 12Z KBUF SOUNDING. ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING ALONG THE MAIN COLD FRONT. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT. OUTLOOK... SUNDAY...MVFR CIGS LIFTING BY AFTERNOON. SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR. WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS. && .MARINE... THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041. SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL/HITCHCOCK MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
751 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... SKIES WILL BE MOSTLY CLOUDY ACROSS THE REGION THIS MORNING. DESPITE THE CLOUD COVER...EXPECT JUST A FEW SPRINKLES THIS MORNING...WITH THE STEADIER SHOWERS HOLDING OFF UNTIL HE AFTERNOON HOURS. AN AREA OF SHOWERS NW OF LAKE ONTARIO AT DAYBREAK WILL CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A DIFFLUENT UPPER LEVEL FLOW. WITH THE FEATURE ON RADAR WE HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO ENTER N OF I-90 EARLY THIS AFTERNOON...WITH SHOWERS THEN SLIDING ESE INTO THE FINGER LAKES AND EAST OF LAKE ONTARIO LATE AFTERNOON. WITH A FEW LIGHTNING STRIKES UPSTREAM...CANNOT RULE OUT AN ISOLATED THUNDERSTORM AS THE SHOWERS MOVE ACROSS LAKE ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY. HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF LAKE ONTARIO. ALSO...TEMPERATURES WILL DROP AS THE SHOWERS MOVE IN...SO HIGHS MAY COME LATE MORNING IN SOME SPOTS. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM BUFFALO TO NIAGARA FALLS. A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION. THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW TO MID 60S FOR MUCH OF THE REGION. SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT. ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT. MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A COLD FRONT IN THE WESTERN GREAT LAKES. ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS. THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S.. AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE JULY THAN MID-SEPTEMBER. IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000 J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND WEDNESDAY NIGHT. THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE AVERAGE. THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK BREEZE. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AT 12Z...TAF SITES SHOULD START OFF VFR. AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT. OUTLOOK... SUNDAY...MVFR CIGS LIFTING BY AFTERNOON. SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR. WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS. && .MARINE... THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT AND MONDAY...AS HIGH PRESSURE BUILDS IN. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR LEZ020-041. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
622 AM CDT SAT SEP 7 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT SAT SEP 7 2013 TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000 J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM 700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO BECOME ALL THAT ORGANIZED OR SEVERE. BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY. QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT. HAVE RAISED SKY COVER IN THE EAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 406 AM CDT SAT SEP 7 2013 EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA. THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST. SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70. LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14 CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30 POP IN THAT REGION. MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST. CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT. INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS. MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION PARALLEL TO THE FRONT. BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT. LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH OF TEMPERATURES THE FOLLOWING WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 619 AM CDT SAT SEP 7 2013 A WEAK SHORT WAVE WILL MOVE THROUGH THE AREA THIS MORNING RESULTING IN HIGH BASED ISOLATED-SCATTERED STORMS. EXPECT SKIES TO BECOME PARTLY CLOUDY BEHIND THE WAVE. NORTHEAST FLOW WILL PREVAIL ACROSS THE REGION BECOMING EASTERLY TONIGHT. THERE IS A CHACE THAT STRATUS MAY TRY TO DEVELOP...THOUGH CONFDIENCE IS HIGHER EAST OF I-29 AND HAVE NOT INCLUDED IN THE FORECAST QUITE YET. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM... LONG TERM...CHENARD AVIATION...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
655 AM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST ON MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 210 AM EDT SATURDAY... GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY. OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW 80S WITH MAINLY 70S ELSW. NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT. HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM EDT SATURDAY... A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND. GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST. TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON MONDAY. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 345 PM EDT FRIDAY... HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER. BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM EDT SATURDAY... WIDE VARIETY OF CONDITIONS TO INIT THIS MORNING WITH IFR/LIFR IN FOG/STRATUS IN SOME OF THE VALLEYS SUCH AS LWB...AND LOW END MVFR CIGS IN SPOTS OVER THE EAST LIKE DAN/LYH PER BANDS OF STRATO-CU. OTRW OUTSIDE OF PATCHY LOW CLOUDS/FOG...MAINLY VFR UNDER PERIODIC HIGH CLOUDS WITH A WEAK DISTURBANCE APPROACHING FROM THE NW. STILL EXPECTING ANY LOW CLOUDS AND/OR FOG TO FADE BY MID OR LATE MORNING IF NOT SOONER AS THE FLOW TURNS MORE SW TO W BY AFTERNOON. HOWEVER WILL CONTINUE LOW CONDITIONS FOR A WHILE LONGER AND PERHAPS SPILL LOW DECK WESTWARD BACK TO THE BLUE RIDGE BEFORE TRANSITIONING ALL LOCATIONS TO A SCTD-BKN CU CANOPY WITH HEATING THIS AFTERNOON. SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH TO ALONG THE MID ATLANTIC COAST BY THIS EVENING PROVIDING MAINLY CLEAR SKIES OUTSIDE OF PASSING MID/HIGH CLOUDS OVERNIGHT. AGAIN APPEARS THE DEEPER VALLEYS SUCH AS LWB WILL DROP OFF TO IFR/LIFR AT TIMES WITH MAINLY VFR ELSW OUTSIDE OF PATCHY FOG LATE IN THE EAST. ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE AREA LATE SUNDAY...THEN STALL AND EVENTUALLY WASH OUT JUST TO OUR SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST BUILDS EAST TOWARD THE MID-ATLANTIC. THIS MAY SPARK A ROUND OF SHRA/TSRA ESPCLY MOUNTAINS SUNDAY AFTERNOON. OTRW EXPECT A RETURN TO MORE TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY- DRIVEN SHRA/TSRA INTO SUNDAY EVENING WHEN THE FRONT MOVES SOUTH THROUGH THE REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE OUTSIDE MORNING FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS THE AIR MASS ACROSS THE REGION BECOMES INCREASINGLY MOIST WITH DEWPOINTS IN THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS POINT...NO WIDESPREAD EXTENDED DURATION OF POOR AVIATION CONDITIONS ARE EXPECTED THROUGH MID WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/WERT NEAR TERM...JH SHORT TERM...DS LONG TERM...NF AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
431 AM PDT Sat Sep 7 2013 .SYNOPSIS... The low pressure system responsible for showers and thunderstorms the last couple of days will bring another round of wet weather to the Cascades and northern mountains again today. Sunday will be a drier day for most of the Inland Northwest with showers limited to mainly the Idaho Panhandle. Dry, summer-like weather will return Monday through Thursday as a strong high pressure ridge develops over the region. && .DISCUSSION... Today through Sunday...A large closed low near Republic will be nearly stationary today...before moving east towards the North Idaho Panhandle tonight...and then exiting the area into Montana on Sunday. For this morning main focus is the wrap around band near the North Washington Cascades on the back side of the low where a steady light rain has been falling around Stehekin. The HRRR has been consistent with a large area of light rain over far southwest BC dropping southeast into Mazama, Stehekin early this morning spreading east into Chelan...Brewster...and the Waterville Plateau during the mid morning hours. While this rain will be light...additional rain on saturated ground where mud slides have already occurred may result in additional slides although confidence is marginal of this. Given uncertainty will continue with current Flash Flood Watches for the East Slopes of the Cascades and Wenatchee area. This wrap around band will swing northeast towards Colville and Chewelah during the early afternoon. Cloud cover associated with this may limit thunderstorm chances this afternoon over the Northeast Washington Mountains and Idaho Panhandle. West of this band over the Okanogan Highlands, Okanogan Valley, and East Slopes of the Cascades a better potential for isolated thunderstorms exists with sun breaks more likely to develop. Less instability will exist from Spokane southward due to further proximity from low with only isolated showers at most expected for today. Cloud cover today will keep temperatures below average over all of the region. Tonight showers will decrease with the loss of daytime heating and be confined mainly to northeast Washington and North Idaho with the closed low tracking across this region. Then on Sunday showers will continue in these areas although with the low departing out of the area showers will only be scattered in nature with a slight chance of afternoon thunderstorms. A short wave ridge will approach the Cascades late Sunday afternoon which will allow for more pronounced warming over Central Washington with less cloud cover and showers compared to today. JW Sunday Night: The exiting upper trough may yield some early evening showers over the Idaho Panhandle, but 500mb temperatures will be warming and instability profiles don`t suggest more than isolated thunder potential prior to sunset. Monday through Friday: Summer will return next week with temperatures well above average. There is good model agreement through about Thursday that a high amplitude high pressure ridge will develop over the Pacific Northwest. Wednesday and Thursday look to be the warmest days of the week with 850mb temperatures in the 22-24C range. Many lowland areas will be in the upper 80s to lower 90s which is about 10 degrees above average. Forecast confidence diminished markedly Friday into next weekend. There is very little agreement between the 00z models and run-to- run consistency has not been good either. A cooling trend into next weekend is probable, but the timing/track/intensity of an incoming Pacific trough (and subsequent ridge breakdown) is highly uncertain at this time. /GKoch && .AVIATION... 06Z TAFS: Low pressure will remain over the region through 12z Sunday. The low will be positioned over the northern mountains with the bulk of the showers occurring in the Cascades and areas north of the Columbia Basin. Isolated afternoon thunderstorms are also expected in these areas. Several cloud layers will be present with mid level clouds associated with the low as well as lower cloud layers this morning due to abundant boundary layer moisture. CIGS will be primarily VFR...with occasional MVFR CIGS possible around Wenatchee, Moses Lake, and Spokane area TAFS. && .PRELIMINARY POINT TEMPS/POPS... Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0 Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0 Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0 Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0 Colville 70 50 81 51 85 51 / 70 30 20 10 0 0 Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10 Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10 Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0 Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0 Omak 74 54 83 56 86 57 / 70 30 10 10 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flash Flood Watch through this evening for East Slopes Northern Cascades-Wenatchee Area. && $$
AREA FORECAST DISCUSSION
NWS TUCSON AZ
210 PM MST SAT SEP 7 2013 .SYNOPSIS...ABUNDANT MOISTURE WILL PRODUCE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH TUESDAY. A GRADUAL DECREASE IN MOISTURE WILL THEN LEAD TO REDUCED SHOWER AND THUNDERSTORM ACTIVITY DURING THE SECOND HALF OF THE UPCOMING WEEK. && .DISCUSSION...PERSISTENT AREA OF SHOWERS CONTINUED ACROSS ERN PIMA...SWRN GRAHAM...WRN COCHISE AND ERN SANTA CRUZ COUNTIES THIS AFTERNOON. RADAR RAINFALL ESTIMATES AND GAUGE MEASUREMENTS RANGED FROM JUST A FEW HUNDREDTHS OF AN INCH TO ABOUT 0.20 INCH DURING THE PAST 3 HOURS. SEVERAL RUC HRRR SOLUTIONS MAINTAIN THIS AREA OF SHOWERS DURING THE NEXT FEW HOURS FOLLOWED BY STRONGER PRECIP ECHOES TO OCCUR THIS EVENING ACROSS GREENLEE/GRAHAM/COCHISE COUNTIES. HAVE MAINTAINED SCATTERED SHOWERS AND ISOLATED TSTMS THRU TONIGHT. SUN-MON... OPTED TO INCREASE POPS GENERALLY 5-15 PERCENT THIS PERIOD. 07/12Z GFS/ECMWF WERE SIMILAR WITH MOVING WEAK UPPER LOW OVER SRN SONORA MIDDAY SUN NORTHWARD INTO FAR SE AZ BY MON AFTERNOON. NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS SHOULD PREVAIL...PARTICULARLY SUN NIGHT-MON AS SYSTEM MOVES INTO THE AREA. PER COORD WITH WFO/S PSR/ FGZ...HAVE OPTED TO DEFER ANY FLASH FLOOD WATCH ISSUANCES TO SUBSEQUENT SHIFTS. WIDESPREAD RAINFALL SHOULD OCCUR. HOWEVER...MUCH UNCERTAINTY EXISTS AT THIS TIME REGARDING THE POTENTIAL FOR WIDESPREAD FLASH FLOODING. TUE-WED... THE PROSPECT FOR SEVERE THUNDERSTORMS MAY INCREASE PARTICULARLY TUE AFTERNOON/EVENING AS AXIS OF DEEPER MOISTURE SHIFTS EWD INTO WRN NEW MEXICO. MEANWHILE...MID-LEVEL DRYING IS PROGGED TO MOVE INTO WRN SECTIONS IN RESPONSE TO SWLY FLOW ALOFT AROUND WEAK LOW PRESSURE CENTERED OVER THE GREAT BASIN. THE INTERFACE BETWEEN THE DEEPER MOISTURE JUST EAST OF THE AREA AND THE SOMEWHAT DRIER AIR WEST MAY LEAD TO STRONGER THUNDERSTORMS TUE AFTERNOON AND TUE EVENING...AND PERHAPS NEAR THE NEW MEXICO BORDER WED AFTERNOON. THUR-SAT... EXPECT SOMEWHAT LESS COVERAGE OF SHOWERS/TSTMS AS DEEPER MOISTURE IS PROGGED TO REMAIN JUST EAST OF THIS FORECAST AREA. HAVE OPTED FOR SCATTERED AFTERNOON AND EVENING SHOWERS/TSTMS ACROSS ERN SECTIONS WITH ISOLATED SHOWERS/TSTMS FROM TUCSON WWD/NWWD. HIGH TEMPS SUN WILL BE SIMILAR TO TEMPS ACHIEVED THIS AFTERNOON. COOLER MON FOLLOWED BY NO SIGNIFICANT CHANGE IN DAYTIME TEMPS TUE. HIGH TEMPS MON-TUE ARE FORECAST TO AVERAGE ABOUT 10 DEGS F OR SO BELOW NORMAL. A WARMING TREND IS ON TAP WED-FRI...WITH DAYTIME TEMPS FRI-SAT TRENDING CLOSE TO SEASONAL NORMALS FOR MID-SEPTEMBER. && .AVIATION...VALID THRU 00Z 09/09. SCT-BKN MID LVL CLOUD DECK HAS LIMITED CONVECTIVE POTENTIAL TODAY FOR BOTH KOLS/KTUS. HOWEVER...THERE REMAINS AMPLE MOISTURE IN PLACE SO CONTINUED -SHRA/VCSH POSSIBLE. CU FIELD DEVELOPING E OF THE KDUG TO KSAD LINE SO GIVEN MID LVL STEERING FLOW ISOLD TS POSSIBLE THRU 03Z ACROSS THIS AREA. OUTSIDE OF A BRIEF +SHRA EXPECT VFR CONDITIONS AND LIGHT WINDS TO PREVAIL THRU THE PERIOD. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH TUESDAY. STRONG...GUSTY AND ERRATIC WINDS WILL OCCUR WITH THE STRONGER THUNDERSTORMS. THEREAFTER...DECREASED MOISTURE WILL LEAD TO ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS DURING THE LATTER PART OF THE UPCOMING WEEK. BELOW NORMAL DAYTIME TEMPERATURES WILL OCCUR THROUGH WEDNESDAY FOLLOWED BY A WARMING TREND THURSDAY AND FRIDAY. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON DISCUSSION/FIRE WEATHER...FRANCIS AVIATION...MEADOWS
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
115 PM PDT SAT SEP 7 2013 .SYNOPSIS... SCATTERED THUNDERSTORMS WILL DIMINISH THIS EVENING OVER THE MOUNTAINS...BUT MAY REFIRE AGAIN ON SUNDAY AFTERNOON WITH LINGERING MONSOONAL MOISTURE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST COAST EARLY NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING THUNDERSTORM CHANCES OVER THE MOUNTAINS AND DESERTS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... SHOWERS AND TSTMS GOT AN EARLY START LATE THIS MORNING OVER THE MOUNTAINS...AND EXPECT IT WILL BE ANOTHER VERY ACTIVE AFTERNOON AND EVENING. GPS SOUNDERS OVER THE DESERTS ARE ESTIMATING PW VALUES AROUND TWO INCHES SO PLENTY OF FUEL FOR TORRENTIAL RAINFALL AGAIN UNTIL AROUND SUNSET. A FEW TSTMS MAY POP OVER THE INLAND EMPIRE AS WELL...BUT WATER VAPOR IMAGERY AND SOUNDERS WEST OF THE MOUNTAINS SHOW THE MOIST LAYER IS SHALLOW. QUITE WARM TO HOT AGAIN THIS AFTERNOON WITH TEMPS IN THE 80S NEAR THE COAST...AND 90S TO AROUND 100 F INLAND. VERY WEAK SFC PRESSURE GRADIENTS AT MIDDAY. DUE TO THE VERY HIGH DEWPOINTS OVER THE LOWER DESERTS...THE OPERATIONAL EMC RAP INDICATES SURFACE-BASED CAPES APPROACHING 3500 OVER THE LOWER DESERTS THIS AFTERNOON. SHOULD THIS AREA CONVECT... THUNDERSTORMS COULD APPROACH SEVERE LIMITS AS WELL AS PRODUCE TORRENTIAL DOWNPOURS. THE 18Z 3-KM HRRR HAS MODELED THE BEGINNING OF THE CONVECTION WELL TODAY AND DOES NOT INDICATE ANY ACTIVITY IN THE COACHELLA VALLEY THIS AFTERNOON. HOWEVER CONVECTION DOES BECOME INTENSE OVER THE SANTA ROSAS...AND OVER THE SAN DIEGO COUNTY DESERTS. NUMEROUS HRRR RUNS ALSO SHOW ISOLATED CONVECTION OVER THE INLAND EMPIRE. ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT HAVE THE DEEP LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS. GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/ THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME... THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST... DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK. REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS CRITICAL. BOTH THE 12Z ECMWF/GFS SHOW THE TROUGH AXIS E OF THE CWA ON MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR EAST AND THE 12Z ECMWF SEEMS TO BE TRENDING CLOSER THE THE GFS SOLUTION. THE NAM 12 STILL SHOWS THE MTNS EAST CONVECTING ON MON...BUT NO NOCTURNAL ACTIVITY OVER THE AREA. POPS HAVE BEEN PARED BACK EARLY NEXT WEEK...EXPECTING THE BIGGER THREAT MORE TO THE EAST. LOOKING AHEAD TO THE END OF NEXT WEEK...12Z GLOBAL MODEL RUNS STILL DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS FAVORED AND A BIT WARMER. && .AVIATION... 072010Z...COAST/VALLEYS...FROM 2100 UTC THROUGH 08/0300 UTC...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS CLDS AOA 8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG REACHING KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING. OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING. MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS THROUGH 08/0100 UTC WITH BASES 7000-10000 FT MSL AND CB TOPS TO 40000 FT MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY RAIN...SMALL HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS. OTHERWISE...UNRESTRICTED VIS THROUGH SUNDAY MORNING. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS. PZ...NONE. && $$ PUBLIC...JAD AVIATION...HARRISON
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1059 AM MDT SAT SEP 7 2013 .UPDATE... ISSUED AT 1057 AM MDT SAT SEP 7 2013 AN AREA OF LIGHT SHOWERS WITH A LIGHTNING STRIKE EVERY SO OFTEN...CONTINUES TO MOVE NORTH ACROSS NORTHWEST COLORADO THIS MORNING. THIS ACTIVITY WAS LOCATED FROM THE VICINITY OF THE CATHEDRAL BLUFFS IN WESTERN RIO BLANCO COUNTY TO WEST OF HIGHWAY 13 FROM HAMILTON/CRAIG TO BAGGS WY LATE THIS MORNING. THESE SHOWERS WILL CONTINUE NORTHWARD INTO WY BY NOON OR SHORTLY THEREAFTER. OTHERWISE CONVECTION IS JUST STARTING TO BUILDUP OVER THE HIGHER TERRAIN WITH THAT TREND EXPECTED TO CONTINUE INTO THE AFTERNOON AS PER PREVIOUS FORECAST. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 358 AM MDT SAT SEP 7 2013 ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA ACTIVITY APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH NORTHWEST ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT FIELDS ON THE 00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING TOWARD THE FOUR CORNERS THIS MORNING...BEFORE DAMPENING OUT SHORTLY AFTER SUNRISE. THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL CONTINUE FOR ANOTHER COUPLE HOURS. HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY... WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS. TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL. SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL. GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY ESPECIALLY OVER NE UT-FAR NW CO. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 358 AM MDT SAT SEP 7 2013 SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST NEAR THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL BELOW 14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS. TEMPERATURES FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY. DRIER AIR TRIES TO INVADE NE UTAH MONDAY NIGHT. THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN EXPERIENCING. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1057 AM MDT SAT SEP 7 2013 ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...FAVORING THE HIGHER TERRAIN. GUSTY AND ERRATIC OUTFLOW WINDS...HEAVY RAIN AND SMALL HAIL WILL BE ASSOCIATED WITH THE STRONGER THUNDERSTORMS THROUGH 03Z THIS EVENING. MOISTURE WILL CONTINUE TO SURGE BACK INTO THE REGION AFTER 06Z TONIGHT WITH SHOWERS LINGERING THROUGH THE NIGHT. EXPECT LOCAL MVFR CIGS AND VSBYS NEAR THE STRONGER THUNDERSTORMS THIS AFTERNOON...ESPECIALLY ACROSS THE MOUNTAINS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...EH SHORT TERM...JDC/JOE LONG TERM...JOE/JDC AVIATION...EH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
408 PM CDT SAT SEP 7 2013 .DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY... FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY. THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE POPS MAY BE TOO HIGH. ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT MAINTAINED A DRY FORECAST FOR NOW. VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925 MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY. GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD ONLY IN THE LOW-MID 60S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY... MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 21Z... * OUTFLOW BOUNDARY SURGING SOUTH-SOUTHWEST AND IS EXPECTED TO PRODUCE A WIND SHIFT TO NORTHEAST AT BOTH ORD/MDW BETWEEN 2115-2130Z. WIND LIKELY TO GUST BRIEFLY AROUND 20 KT...THEN BECOME MORE EAST/SOUTHEAST OVER NEXT FEW HOURS. * SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING. * SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING * LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY MORNING. ALLSOPP/RATZER //DISCUSSION...UPDATED 18Z... SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT... WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING. THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW CHANCE OF THUNDER NEAR ORD THIS AFTERNOON. INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS THROUGH THE DAY SUNDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 22Z... * HIGH CONFIDENCE IN OUTFLOW WINDSHIFT AT ORD...MEDIUM-HIGH MDW TO NORTHEAST SHORTLY. * MEDIUM-HIGH CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY THIS EVENING. * MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY. * MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT BUT LOW TO MEDIUM CONFIDENCE IN TIMING. ALLSOPP/RATZER //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH TUESDAY...VFR. TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE. WEDNESDAY THROUGH FRIDAY...VFR. MDB && .MARINE... 129 PM CDT A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO 25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES ARE EXPECTED. THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF ON EXTENDING THE ADVISORY INTO THIS PERIOD. THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA. LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM SUNDAY. SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11 PM SUNDAY. && $$ 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
325 PM CDT SAT SEP 7 2013 .DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY... FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY. THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE POPS MAY BE TOO HIGH. ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT MAINTAINED A DRY FORECAST FOR NOW. VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925 MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY. GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD ONLY IN THE LOW-MID 60S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY... MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO CAUSE A WIND SHIFT AT ORD. * SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING. * SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING * LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY MORNING. ALLSOPP //DISCUSSION...UPDATED 18Z... SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT... WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING. THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW CHANCE OF THUNDER NEAR ORD THIS AFTERNOON. INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS THROUGH THE DAY SUNDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY THIS EVENING. * MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY. * MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT BUT LOW TO MEDIUM CONFIDENCE IN TIMING. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH TUESDAY...VFR. TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE. WEDNESDAY THROUGH FRIDAY...VFR. MDB && .MARINE... 129 PM CDT A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO 25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES ARE EXPECTED. THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF ON EXTENDING THE ADVISORY INTO THIS PERIOD. THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA. LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM SUNDAY. SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11 PM SUNDAY. && $$ 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
304 PM CDT SAT SEP 7 2013 .DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY... FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY. THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE POPS MAY BE TOO HIGH. ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT MAINTAINED A DRY FORECAST FOR NOW. VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925 MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY. GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD ONLY IN THE LOW-MID 60S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY... WILL BE ISSUED SHORTLY. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO CAUSE A WIND SHIFT AT ORD. * SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING. * SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING * LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY MORNING. ALLSOPP //DISCUSSION...UPDATED 18Z... SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT... WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING. THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW CHANCE OF THUNDER NEAR ORD THIS AFTERNOON. INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS THROUGH THE DAY SUNDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY THIS EVENING. * MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY. * MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT BUT LOW TO MEDIUM CONFIDENCE IN TIMING. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH TUESDAY...VFR. TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE. WEDNESDAY THROUGH FRIDAY...VFR. MDB && .MARINE... 129 PM CDT A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO 25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES ARE EXPECTED. THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF ON EXTENDING THE ADVISORY INTO THIS PERIOD. THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA. LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM SUNDAY. SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11 PM SUNDAY. && $$ 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 QUAD CITIES IA IL
106 PM CDT SAT SEP 7 2013 .UPDATE... ISSUED AT 709 AM CDT SAT SEP 7 2013 FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW HUNDREDTHS. PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT SHOWERS CAN BE EXPECTED FOR THE MORNING. DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE EVENING HOURS. ..08.. && .SYNOPSIS... ISSUED AT 324 AM CDT SAT SEP 7 2013 06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH 50S OVER THE EASTERN GREAT LAKES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT SEP 7 2013 RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA. SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA. THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST. MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON. TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF THE AREA WILL REMAIN DRY TONIGHT. ..08.. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT SEP 7 2013 IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE. THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S. SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z. TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1257 PM CDT SAT SEP 7 2013 SURFACE LOW...UPPER LEVEL DISTURBANCE AND APPROACHING COLD FRONT TO COMBINE FOR AT LEAST SCATTERED SHOWERS AND STORMS BY LATE AFTN THROUGH THIS EVE. BRIEF IFR TO MVFR VSBYS POSSIBLE WITH THE STRONGER SHOWERS AND ANY STORMS. OVRNGT INTO SUN AM SOME OF THE MODEL GUIDANCE SUPPORTIVE OF STRATUS AND FOG WITH IFR TO MVFR CONDITIONS DEVELOPING WITH COOLER NORTHEASTERLY FLOW AND RESIDUAL LOW LEVEL MOISTURE. WINDS THIS AFTERNOON WILL BE MAINLY FROM THE SOUTHWEST 5-10 KTS WITH SOME LOCALIZED GUSTS NEAR 18 KTS. THIS EVE FOR A TIME WINDS WILL BE LIGHT AND VARIABLE BEFORE SHIFTING TO NORTH WITH FRONTAL PASSAGE AND EVENTUALLY BECOMING E/NE BY 12Z SUN. SOME GUSTS OF 15-20 KTS POSSIBLE SUN AM. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...08 SHORT TERM...08 LONG TERM...DLF AVIATION...05
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
403 PM EDT SAT SEP 7 2013 .SHORT TERM...THIS EVENING TONIGHT DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO THE FORECAST DIFFICULTY. THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND 1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID. NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE. THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA 20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z. THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW STRATUS BLANKET 12Z. && .LONG TERM...SUNDAY THROUGH NEXT SATURDAY COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND. UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED IN A MORE STABLE WARM SECTOR. IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA. FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT. WILL WATCH TRENDS HOWEVER. COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH. UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES. THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY. && .MARINE... THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB. LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET. && .AVIATION...ISSUED 144 PM EDT SAT SEP 7 2013 //DISCUSSION... TWO TIME WINDOWS FOR PRECIPITATION THIS AFTERNOON. THE FIRST IS WITH ONGOING SHOWER ACTIVITY WITH VFR CEILINGS AND A MID CLOUD DECK. THIS ACTIVITY WILL PUSH EASTWARD DURING THE FIRST COUPLE OF HOURS OF THE TAF PERIOD. THEN POTENTIAL EXISTS FOR THUNDERSTORM DEVELOPMENT AHEAD OF AN APPROACHING COLD FRONT BOUNDARY. DID GO AGGRESSIVE WITH TIMING A 3 HOUR TEMPO GROUP FROM NORTH TO SOUTH. THE SUPPORT FOR SHOWER AND THUNDERSTORMS SHOULD END AT THE SOUTHERN TAF SITES BETWEEN 0-2Z. FOR DTW...PREVAILING SOUTHWEST FLOW WILL CONTINUE BEFORE A MORE ABRUPT SHIFT TO THE NORTHEAST TAKES PLACE WITH THE PASSAGE OF THE SURFACE TROUGH TONIGHT AROUND 04Z. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE THAT CEILING HEIGHTS WILL LOWER BELOW 5000 FT AFTER 6Z TONIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO PORT SANILAC...FROM 2 AM SUNDAY TO 10 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM SUNDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY. && $$ SHORT TERM...CB LONG TERM....HLO MARINE.......CB AVIATION.....CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 PM EDT SAT SEP 7 2013 .UPDATE... ISSUED AT 1057 AM EDT SAT SEP 7 2013 TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS ASSOCIATED WITH THE FRONT SHOULD BE DONE. ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON. THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER 70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL BE OUT SHORTLY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 519 AM EDT SAT SEP 7 2013 GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST 24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR. THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z. EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/. LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 505 AM EDT SAT SEP 7 2013 IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST. FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7 DAY FCST. BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF... CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT 12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE GREAT LAKES. SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE... DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM. OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS... ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL INTO THE LWR 40S. MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN. THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI... NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON... ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR. RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF 30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON. BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE... SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA. HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE... NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER. WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS SAT SHOULD BE CLOSER TO NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 140 PM EDT SAT SEP 7 2013 LOW STRATUS AND FOG MOVED INTO ALL THREE TAF SITES OVER THE LAST FEW HOURS. THIS IS DUE TO THE NORTHERLY FLOW BEHIND THE COLD FRONT THAT MOVED THROUGH LAST NIGHT AND PUSHED THE LOW CLOUDS SOUTH OFF LAKE SUPERIOR. EXPECT THESE CONDITIONS TO CONTINUE THROUGH MUCH OF THE AFTERNOON...BUT DRIER AIR ASSOCIATED WITH HIGH PRESSURE NEAR LAKE WINNIPEG HAS ALREADY BEEN SEEN ON VISIBLE SATELLITE SLIDING SOUTH OVER NORTHERN LAKE SUPERIOR. IN ADDITION...THE CEILINGS/VISIBILITIES HAVE ALREADY STARTED TO MOVE UPWARD AT KCMX AND BASED OFF WEBCAMS IN THE KEWEENAW. THUS...SHOULD HAVE CONDITIONS HEADING TO VFR FROM NORTH TO SOUTH BY LATE AFTERNOON INTO EARLY EVENING. THIS DRY AIR WILL LEAD TO CLEAR SKIES AND WEAKENING WINDS THROUGH THE REST OF THE TAF PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 519 AM EDT SAT SEP 7 2013 A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...SRF SHORT TERM...KF LONG TERM...ROLFSON AVIATION...SRF MARINE...KF
AREA FORECAST DISCUSSION
NWS BILLINGS MT
306 PM MDT SAT SEP 7 2013 .SHORT TERM...VALID FOR SUN AND MON... INGREDIENTS ARE IN PLACE ACROSS THE REGION FOR A BUSY AFTERNOON AND NIGHT. UPPER TROUGH OVER WASHINGTON STATE SLOWLY MOVING EASTWARD. LOW LEVEL JET OVER EAST HAS BROUGHT UP AN ABUNDANT AMOUNT OF MOISTURE ACROSS THE EASTERN SECTIONS OF MONTANA AND NEARBY AREAS. MONSOONAL MOISTURE IS EXPECTED TO STREAM ACROSS THIS SAME AREA. PRECIPITABLE WATER LEVELS UP AROUND 1.50 INCHES...WHICH IS HIGHLY UNUSUAL FOR THIS TIME OF YEAR...WILL LIKELY LEAD TO THUNDERSTORMS WITH VERY HEAVY RAINFALL. WE HAVE ALSO SEEN SOME TRAINING CELLS OVER CUSTER COUNTY ALREADY TODAY. THUS...THE FLASH FLOOD WATCH WILL REMAIN IN PLACE THROUGH 6AM. THE HRRR MODEL DEVELOPS TWO WAVES OF CONVECTIVE ACTIVITY...PRIMARILY HITTING AREAS FROM BIG HORN COUNTY NORTH AND EAST...AND THE LAST WAVE CARRIES WELL INTO THE NIGHT OUT EAST. DUE TO INSTABILITY FACTORS AND SHEAR PROFILES...WE COULD ALSO SEE SOME HAIL AND DAMAGING WIND...THOUGH AT THIS TIME I FEEL TORRENTIAL RAINFALL IS MORE OF A THREAT. THE SHEAR PROFILE AND OVERALL PATTERN DOES ALSO SUPPORT THE SLIGHT CHANCE OF AN ISOLATED TORNADO IN THE EASTERN COUNTIES...THOUGH WOULD LIKE TO SEE SHEAR JUST A BIT STRONGER...LESS INITIAL CLOUD COVER AND GREATER INSTABILITY. NEVERTHELESS...WE WILL BE MONITORING STORMS CLOSELY FOR DEEP ROTATION...ESPECIALLY FROM MILES CITY TO BROADUS EASTWARD. AS STORMS DIMINISH IN THE EAST LATE TONIGHT...UPPER TROUGH BEGINS TO SWING THROUGH NORTH/CENTRAL MONTANA IN THE MORNING. BEST MOISTURE AND SHEAR PROFILES WILL BE LOCATED FURTHER EAST...BUT LIFT WILL BE MUCH GREATER ACROSS THE REGION WITH GOOD Q VECTOR FORCING. HEAVY RAIN IS STILL A GOOD BET TOMORROW WITH SOME STORMS...AND MAYBE LOTS OF SMALL HAIL OR GROUPEL. BT .LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT... SEASONABLY WARM WEATHER IS EXPECTED NEXT WEEK...WITH AN INCREASING CHANCE OF CONVECTION BY FRI AND SAT WHEN THE 12 UTC GUIDANCE SHOWS ANOTHER SURGE OF MONSOONAL MOISTURE ARRIVING. AN AMPLIFIED 500-HPA RIDGE WILL BECOME ESTABLISHED ACROSS THE REGION ONCE AGAIN BY MID- WEEK WITH ABOVE-NORMAL HEIGHTS FOR THIS TIME OF THE YEAR. ITS AXIS APPEARS ORIENTED MORE NORTHWEST-SOUTHEAST THAN LAST WEEK/S VERSION OF A LATE-SEASON RIDGE THOUGH...WHICH WILL LIKELY HELP MAINTAIN AN EASTERLY LOW-LEVEL FLOW AND A SOMEWHAT COOLER AIR MASS IN SOUTHERN MT AND NORTHERN WY THAN WHAT WE HAVE EXPERIENCED RECENTLY. BY LATE IN THE WEEK...GUIDANCE SUGGESTS SHORT WAVE ENERGY WILL LIFT ACROSS THE AREA AND LOWER THE 500-HPA HEIGHTS AS PRECIPITABLE WATER AGAIN RISES ABOVE AN INCH. THE RESULT SHOULD BE AT LEAST ISOLATED SHOWER AND STORM ACTIVITY...AND INCREASING CLOUDS TO HOLD BACK HIGHS SOME MORE. IF TRENDS IN THE 12 UTC GUIDANCE HOLD TRUE WITH LATER CYCLES THEN WE MAY NEED TO LOWER HIGHS A BIT THROUGH THE PERIOD AND RAISE POPS A BIT BY FRI AND SAT. SCHULTZ && .AVIATION... THUNDERSTORMS WILL AFFECT THE AREA THROUGH THIS EVENING...WITH THE HIGHEST PROBABILITIES OF STORMS FROM AROUND KSHR TO KMLS AND KBHK. IFR OR POSSIBLY EVEN LIFR CONDITIONS IN HEAVY RAIN ARE EXPECTED IN THE MOST INTENSE STORMS...WITH A THREAT OF LARGE HAIL AND DAMAGING WINDS TOO. THE ACTIVITY SHOULD SLOWLY DIMINISH BY LATE NIGHT...BUT LOW CEILINGS MIGHT FORM IN ITS WAKE BY SUNDAY MORNING. SCHULTZ && .PRELIMINARY POINT TEMP/POPS... SUN MON TUE WED THU FRI SAT ----------------------------------------------------------- BIL 060/081 057/079 054/084 055/085 058/088 060/088 057/088 45/T 50/B 00/U 00/U 00/U 12/T 22/T LVM 053/080 048/077 046/084 046/085 051/087 052/090 054/090 34/T 31/U 00/U 00/U 02/T 23/T 32/T HDN 059/083 055/081 052/085 053/087 057/090 058/089 059/090 56/T 51/B 00/U 00/U 00/U 11/U 12/T MLS 063/082 059/080 055/084 055/085 057/086 060/086 058/088 56/T 62/W 10/U 00/U 00/U 11/U 11/U 4BQ 062/084 058/081 052/084 054/086 057/086 058/086 059/090 65/T 52/W 00/U 00/U 00/U 12/T 22/T BHK 061/081 057/077 053/080 054/081 054/080 056/081 055/081 76/T 72/T 11/U 10/U 00/U 11/U 12/T SHR 058/082 053/077 047/083 050/085 053/089 055/087 053/087 45/T 42/W 00/U 00/U 00/U 12/T 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES 29>33-35>38-57-58. WY...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES 98-99. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
143 PM EDT SAT SEP 7 2013 .SYNOPSIS... HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... RADAR IMAGERY EARLY THIS AFTERNOON SHOWING A LARGE AREA OF SHOWERS FROM SOUTHERN ONTARIO EAST ACROSS THE NIAGARA FRONTIER INTO CENTRAL NY. THIS WILL CONTINUE TO DRIFT SLOWLY ESE ACROSS THE AREA THIS AFTERNOON WITH OCCASIONAL SHOWERS. THE SOUTHERN TIER WILL ESCAPE MUCH OF THIS THROUGH LATE AFTERNOON...ESPECIALLY CLOSER TO THE PA STATE LINE. THE SAINT LAWRENCE VALLEY WILL ALSO HAVE PLENTY OF DRY TIME WITH JUST A FEW BRIEF SHOWERS. WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE AREA OF STEADY RAIN OVER LAKE ONTARIO. WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES WILL STRUGGLE AND STAY IN THE MID TO UPPER 60S IN MOST AREAS. THE ONLY EXCEPTION WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY TIME WILL STILL BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN THE VALLEYS THERE. A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION. THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER 50S TO LOWER 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW TO MID 60S FOR MUCH OF THE REGION. SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT. ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT. MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A COLD FRONT IN THE WESTERN GREAT LAKES. ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS. THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S.. AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE JULY THAN MID-SEPTEMBER. IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000 J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND WEDNESDAY NIGHT. THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE AVERAGE. THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK BREEZE. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AN AREA OF SHOWERS ACROSS MUCH OF UPSTATE NY EARLY THIS AFTERNOON WILL CONTINUE THROUGH THE FIRST HALF OF TONIGHT AS A COLD FRONT PUSHES SOUTH ACROSS THE AREA. CONDITIONS WILL STAY VFR MUCH OF THE TIME THROUGH THIS EVENING AS THE LOW LEVELS REMAIN UNSATURATED... ALTHOUGH SOME BRIEF DIPS TO MVFR/IFR VSBY ARE POSSIBLE IN THE HEAVIEST SHOWERS. FOLLOWING THE COLD FRONTAL PASSAGE IN THE 05Z-07Z TIME FRAME... SHOWERS WILL TAPER OFF FROM NORTH TO SOUTH. A FEW LINGERING LIGHT SHOWERS MAY PERSIST THROUGH SUNDAY MORNING ACROSS HIGHER TERRAIN DUE TO UPSLOPE FLOW...AND SOUTHEAST OF LAKE ONTARIO DUE TO SOME WEAK LAKE EFFECT AS COOLER AIR CROSSES THE LAKE. OF MORE IMPORTANCE...A PERIOD OF LOWER CIGS IS EXPECTED FOLLOWING THE COLD FRONTAL PASSAGE AS EXTENSIVE LOW LEVEL MOISTURE BECOMES TRAPPED UNDER A STEEP FRONTAL INVERSION. THIS WILL BRING AREAS OF IFR CIGS LATER TONIGHT THROUGH SUNDAY MORNING. THE LOW CIGS WILL SCATTER OUT FROM NORTH TO SOUTH ON SUNDAY AS DRIER AIR AND SUBSIDENCE BUILD SOUTH OUT OF ONTARIO WITH HIGH PRESSURE BUILDING BACK INTO THE GREAT LAKES. OUTLOOK... MONDAY AND TUESDAY...MAINLY VFR. WEDNESDAY...MVFR/VFR. A CHANCE OF THUNDERSTORMS. THURSDAY...MVFR/VFR WITH A CHANCE OF SHOWERS. && .MARINE... THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041. SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR LOZ043-044. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...HITCHCOCK MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1256 PM CDT SAT SEP 7 2013 .UPDATE... ISSUED AT 1240 PM CDT SAT SEP 7 2013 BATCH OF SCATTERED SHOWERS WITH A FEW EMBEDDED LIGHTNING STRIKES TRACKING ALONG THE BOUNDARY NEAR OUR SOUTHERN BORDER. THIS ACTIVITY CONTINUES TO TRACK EAST SOUTHEAST AND SHOULD EXIT THE AREA WITHIN THE NEXT FEW HOURS. WHILE CLEARING IS FORMING BEHIND THIS ACTIVITY...CLOUD COVERAGE IS STALLING THE WARMING ACROSS OUR SOUTHEASTERN HALF. DID LOWER HIGHS A FEW DEGREES MAINLY THROUGH NORTHWEST IOWA AND ADJACENT AREAS WHERE THE CLOUDS WILL HOLD ON LONGEST THIS AFTERNOON. THE ARRIVAL OF SUNSHINE ELSEWHERE SHOULD ALLOW TEMPS TO SHOOT UP FAIRLY QUICKLY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM CDT SAT SEP 7 2013 TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000 J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM 700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO BECOME ALL THAT ORGANIZED OR SEVERE. BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY. QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT. HAVE RAISED SKY COVER IN THE EAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 406 AM CDT SAT SEP 7 2013 EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA. THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST. SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70. LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14 CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30 POP IN THAT REGION. MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST. CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT. INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS. MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION PARALLEL TO THE FRONT. BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT. LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH OF TEMPERATURES THE FOLLOWING WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1240 PM CDT SAT SEP 7 2013 VFR CONDITION PREDOMINATE THROUGH THE TAF PERIOD. SCATTERED STORMS FROM NEAR YANKTON EASTWARD INTO NORTHWEST IOWA WILL CONTINUE TO DISSIPATE AS THEY TRACK EAST SOUTHEAST. COULD SEE A BRIEF DIP TO LOWER CONDITIONS IN THUNDERSTORMS BUT ACTIVITY WILL COME TO AN END BY 20Z. MODELS HINTING AT THE POSSIBILITY OF SOME BROKEN STRATUS FORMING TONIGHT...MAINLY ACROSS SOUTHWEST MINNESOTA. WILL LEAVE OUT MENTION AT TAF SITES FOR NOW BUT WILL CONTINUE TO WATCH FOR DEVELOPMENT. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE... SHORT TERM... LONG TERM...CHENARD AVIATION...
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1103 AM CDT SAT SEP 7 2013 .UPDATE... MOIST AXIS WITH PRECIPITABLE WATER VALUES OF 1.8 ON RAP ANALYSIS AND ON THE NOSE OF THE 850MB MOISTURE TRANSPORT AND THETA-E ADVECTION ARE CENTERED RIGHT OVER CENTRAL AND SOUTH CENTRAL WISCONSIN THIS MORNING. A CLUSTER OF THUNDERSTORMS IS MOVING ACROSS FOND DU LAC AND SHEBOYGAN COUNTIES LATE THIS MORNING. THERE IS POTENTIAL FOR THE STRONGER CORES TO PRODUCE SMALL HAIL WITH THIS ELEVATED CONVECTION...WITH ELEVATED CAPE OF 700-1000 J/KG. MESOSCALE MODELS ARE SUGGESTING CONVECTION TO DEVELOP THIS AFTERNOON OVER SOUTHERN WI AHEAD OF THE SURFACE FRONT. THE FORECAST ISSUE IS WHETHER OR NOT THE SURFACE AND UPPER LEVEL SUPPORT WILL COME IN LINE TOGETHER TO PRODUCE ORGANIZED CONVECTION. IT IS NOT LOOKING LIKE ALL FACTORS WILL BE LINED UP AT THE SAME TIME. IN ADDITION TO AN ACCELERATING SURFACE FRONT...THERE WILL BE UPPER LEVEL SUPPORT FROM A WEAK SHORTWAVE...PERSISTENT LOW LEVEL JET/MOISTURE TRANSPORT AND SUBTLE RIGHT ENTRANCE REGION OF AN UPPER JET. TIMING IS AN ISSUE AS WELL...WITH THE NAM SHOWING BETTER POTENTIAL FOR EARLY CONVECTION AND THE HRRR BEGINNING MID AFTERNOON...AND THE WRF-ARW MODELS SHOWING LATE AFTERNOON/EVENING. COVERAGE WILL BE SPOTTY...BUT WILL PROBABLY NEED TO RAISE THE POPS A BIT. SPC CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW THUNDERSTORMS TO POTENTIALLY BECOME SEVERE WITH WINDS/HAIL DURING THE AFTERNOON. GUSTY NORTHEAST WINDS IN THE WAKE OF THE COLD FRONT WILL WORK DOWN THE LAKE THIS EVENING. DELAYED COLD AIR ADVECTION WILL LEAD TO LOW CLOUDS SPREADING INLAND...PROBABLY THROUGH MADISON...EARLY SUNDAY MORNING. THESE WOULD GRADUALLY RISE AND MIX OUT SUNDAY AFTERNOON. && .AVIATION/18Z TAFS/... ISOLATED SHOWERS WITH A FEW ELEVATED THUNDERSTORMS WILL BE POSSIBLE THROUGH THE MORNING. A CLUSTER OF STRONGER THUNDERSTORMS LOCATED NEAR FOND DU LAC AND OSHKOSH AT 1030 WILL MOVE SOUTHEAST THROUGH SHEBOYGAN THROUGH NOON TODAY. SCATTERED THUNDERSTORMS ARE EXPECTED IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING. ANY STRONGER STORMS COULD PRODUCE SMALL HAIL AND GUSTY WINDS. SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY MORNING IN THE WAKE OF THE COLD FRONT. THESE WILL GRADUALLY RISE TO VFR AND SCATTER OUT SUNDAY AFTERNOON. GUSTY NORTHEAST TO EAST WINDS EXPECTED LATE TONIGHT/SUNDAY MORNING...ESPECIALLY NEAR THE LAKESHORE. && .MARINE... SOUTHWEST WINDS AHEAD OF A COLD FRONT THROUGH EARLY AFTERNOON. A COLD FRONT WILL THEN DROP SOUTH LATE THIS AFTERNOON AND EVENING. NORTHEAST WINDS WILL RAPIDLY INCREASE FROM MID TO LATE EVENING NORTH TO SOUTH BEHIND THE FRONT. WIND GUSTS AND SUBSEQUENT WAVES ARE EXPECTED TO REACH SMALL CRAFT ADVISORY CRITERIA LATE TONIGHT THROUGH SUNDAY AFTERNOON...WITH GRADUAL IMPROVEMENT SUNDAY EVENING. && .PREV DISCUSSION... /ISSUED 312 AM CDT SAT SEP 7 2013/ SHORT TERM... TODAY AND TONIGHT-FORECAST CONFIDENCE MEDIUM TO HIGH. THE UPPER LEVEL WEST/NORTHWEST FLOW ACROSS THE GREAT LAKES WILL BECOME MORE NORTHWEST AS A JET MAX INCREASES TO AROUND 95 KNOTS OVER THE EASTERN LAKE SUPERIOR AREA THIS AFTERNOON...BEFORE DROPPING INTO LOWER MICHIGAN TONIGHT. AT 500 MB A WEAK SHORTWAVE WILL DROP SOUTHEAST ACROSS SOUTHERN WISCONSIN THIS MORNING AND EXIT INTO NORTHERN INDIANA THIS AFTERNOON. THE 850/700 MB FLOW IS WEAK AS IS THE MOISTURE CONVERGENCE/UPWARD MOTION. THE SURFACE COLD FRONT SHOULD ENTER SOUTHERN WISCONSIN DURING THE EARLY AFTERNOON BEFORE EXITING THE FAR SOUTH TOWARD EVENING. ZERO TO 1 KM CAPE VALUES INCREASE TO AROUND 2500 J/KG BUT THIS IS MAINLY POST FRONTAL OVER PORTIONS OF SOUTH CENTRAL WISCONSIN. ALL IN ALL THERE ARE SEVERAL MECHANISMS FOR SHOWER/THUNDERSTORM POTENTIAL...BUT THEY DO NOT ALL COME TOGETHER AT ONE TIME. THEREFORE A BROAD WINDOW OF LOW POPS APPEAR TO BE THE BEST COURSE OF ACTION. SPC CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW THUNDERSTORMS TO POTENTIALLY BECOME SEVERE WITH WINDS/HAIL. THIS WOULD OCCUR DURING THE AFTERNOON. SUNDAY-FORECAST CONFIDENCE HIGH SURFACE HIGH MOVES OUT OF ONTARIO INTO MICHIGAN WITH COOL AND DRY EASTERLY FLOW. UPPER RIDGE REMAINS ANCHORED OVER KANSAS WITH NORTHWEST FLOW PERSISTING OVER SOUTHERN WISCONSIN. MONDAY-FORECAST CONFIDENCE HIGH UPPER TROUGH CURRENTLY OVER PACIFIC NORTHWEST MOVES ACROSS DAKOTAS DURING THE DAY AND INTO MINNESOTA AT NIGHT. THIS FLATTENS UPPER RIDGE WHICH SHIFTS TO THE EAST AND FLOW TURNS TO WESTERLY AND EVENTUALLY SOUTHWEST OVER WISCONSIN. SURFACE LOW OF AROUND 1000 MB MOVES OUT OF DAKOTAS INTO MINNESOTA BY THE EVENING AND THEN CROSSES LAKE SUPERIOR OVERNIGHT. MODELS SHOW NOSE OF LOW LEVEL JET AND SIGNIFICANT WARM ADVECTION REGIME STAYING WELL NORTH OF THE AREA WITH THUNDERSTORMS NOW EVEN FURTHER NORTH THAN MODELS DEPICTED 24 HOURS AGO. LOOKS LIKE BULK OF ACTIVITY WILL BE IN LAKE SUPERIOR AREA AND NORTHWEST ONTARIO. 500 MB HEIGHTS ACTUALLY RISE 10-20 METERS OVER SOUTHERN WISCONSIN. LONG TERM... TUESDAY-FORECAST CONFIDENCE HIGH SURFACE LOW MOVES ACROSS ONTARIO AND INTO QUEBEC WITH FRONT SLOWING DOWN AS IT SAGS SOUTH THROUGH SOUTHERN WISCONSIN IN THE AFTERNOON. GFS IS ONE OF THE SLOWER SOLUTIONS AND HAS 925 MB TEMPS AROUND +28C...SUGGESTING MID TO UPPER 90S. BOTH NAM AND GFS HAVE PLUME OF WARM AND DRY AIR JUST AHEAD OF FRONT SPREADING OUT OF THE CENTRAL PLAINS WHERE IT HAS BEEN RATHER HOT OF LATE AND THERE IS THE POTENTIAL THAT CURRENT FORECAST IN THE LOWER 90S IS CONSERVATIVE. LAST TWO RUNS OF ECMWF HAVE FRONT MAKING IT THROUGH FASTER...WHICH SUGGESTS MORE CONSERVATIVE TEMPERATURE FORECAST IS IN ORDER. GFS ECMWF AND GEMNH ARE IN RATHER GOOD AGREEMENT IN NARROW PLUME OF MOISTURE JUST BEHIND THE SURFACE FRONT WITH MOISTURE ADVECTING OUT OF SOUTHWESTERN STATES. LOOKS LIKE MOST OF THIS CONVECTIVE ACTIVITY WOULD BE AT NIGHT WHEN MODEST HEIGHT FALLS OF ABOUT 20 METERS OCCUR. WEDNESDAY-FORECAST CONFIDENCE HIGH FRONT PUSHES WELL SOUTH BUT A SECOND REINFORCING COOL SURGE IS SHOWN TO COME DOWN AS A BROAD UPPER TROUGH DEVELOPS OVER CENTRAL AND EASTERN CANADA. STRONGEST HEIGHT FALLS OF ABOUT 100 METERS MOVE ACROSS NORTHERN MICHIGAN WITH STRONGER DYNAMICS JUST BRUSHING SOUTHERN WISCONSIN. SHOULD BE DRY WITH TEMPERATURES RETURNING MORE TOWARD SEASONABLE LEVELS. THURSDAY-FORECAST CONFIDENCE HIGH MODELS HAVE COME INTO BETTER AGREEMENT IN DIGGING ANOTHER TROUGH IN NORTHWEST FLOW INTO THE GREAT LAKES. THIS FEATURE IS NOT AS AMPLIFIED AS ECMWF DEPICTED A FEW RUNS AGO...BUT WOULD CONTINUE TO PUSH COOLER AIR INTO GREAT LAKES. IN FACT GFS DROPS 850 MB TEMPS DOWN INTO ABOUT +6C WHICH WOULD BE LOW ENOUGH FOR LAKE EFFECT SHOWERS. HOWEVER THE FETCH WOULD LIKELY KEEP THEM OFFSHORE. FRIDAY-FORECAST CONFIDENCE HIGH DRY AND COOL NORTHWEST FLOW ALOFT SHOULD CONTINUE WITH LARGE SURFACE HIGH OVER MICHIGAN AND LIGHT SURFACE FLOW. AVIATION/12Z TAFS/... MAINLY VFR CONDITIONS. A MID LEVEL CLOUD DECK WILL DROP INTO SOUTHERN WISCONSIN EARLY THIS MORNING WITH ISOLATED SHOWERS WITH A FEW ELEVATED THUNDERSTORMS. THEN SCATTERED THUNDERSTORMS ARE EXPECTED IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING. SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY MORNING. MARINE... SOUTHWEST WINDS AHEAD OF A COLD FRONT THIS MORNING. A COLD FRONT WILL THEN DROP SOUTH THIS AFTERNOON. NORTHEAST WINDS WILL INCREASE TONIGHT BEHIND THE FRONT. WINDS/WAVES MAY REACH SMALL CRAFT ADVISORY CRITERIA LATE TONIGHT AND INTO SUNDAY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM 1 AM TO 7 PM CDT SUNDAY FOR LMZ645-646. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM CDT SUNDAY FOR LMZ643-644. && $$ UPDATE...MRC TODAY/TONIGHT AND AVIATION/MARINE...HENTZ SUNDAY THROUGH FRIDAY...CRAVEN