Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/22/14


SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1015 PM PDT TUE AUG 19 2014 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK WITH ABOVE NORMAL TEMPERATURES. && .UPDATE... THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE. THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT. BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT. THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM- WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM- WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER POSSIBILITIES FOR THURSDAY. && .PREV DISCUSSION... SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND. LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES. && .AVIATION...20/0515Z... OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT. OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE SITUATION CLOSELY. KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY. KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY. && .MARINE...19/900 PM. TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO- OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. && .LOX WATCHES/WARNINGS/ADVISORIES... MARINE WEATHER STATEMENT (SEE LAXMWWLOX). && $$ PUBLIC...HALL/BOLDT AVIATION...GOMBERG MARINE...HALL SYNOPSIS...SETO/HALL WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS PUEBLO CO
307 PM MDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 238 PM MDT WED AUG 20 2014 UPR LEVEL LOW IS SITTING ALONG THE SRN CA COAST TODAY AND IS EXPECTED TO MOVE LITTLE IN THE NEXT 24 HOURS. WV SATELLITE IMAGES SHOWING DRIER AIR HAS WORKED IT WAY INTO WRN CO TODAY. HRRR AND RAP SHOWING MAINLY ISOLD PCPN COVERAGE THIS EVENING OVER WESTERN PORTIONS OF THE FORECAST AREA...WITH ISOLATED TO SCT COVERAGE OVR THE ERN MTS AND SERN PLAINS. A WEAK BOUNDARY IS FORECAST TO MOVE INTO THE PALMER DVD AREA EARLY THIS EVENING AND THEN WORK ITS WAY SOUTH. THIS BOUNDARY MAY HELP KICK OFF ADDITIONAL CONVECTION. THERE COULD BE A FEW LINGERING SHOWERS OR TSTMS OVR THE SERN PLAINS...BUT THINK THAT MOST OF THE PCPN SHOULD END BY 06Z. ON THU...IT DOES NOT LOOK ALL THAT MOIST OVR THE FORECAST AREA. PRECIPITABLE WATER VALUES OVR WRN AREAS ARE FORECAST TO BE SIMILAR TO TODAY...WITH DRIER CONDITIONS OVR ERN AREAS. AS A RESULT THE FORECAST MODELS SHOW MAINLY ISOLD TO SCT POPS OVR THE MTNS IN THE AFTERNOON HOURS...WITH POSSIBLY A FEW STORMS OVR THE LOWER ELEVATIONS. HIGH TEMPS FOR THU SHOULD BE AROUND AVERAGE IN THE HIGH VALLEYS...WITH SLIGHTLY ABOVE NORMAL READINGS OVR THE SERN PLAINS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 238 PM MDT WED AUG 20 2014 NOT MUCH CHANGE TO THE FORECAST THINKING WITH THE GFS COMING INTO LINE WITH THE ECMWF AND NAM SOLUTIONS. ENSEMBLES ARE STILL DISPLAYING QUITE A BIT OF SPREAD BY EARLY NEXT WEEK...BUT CONFIDENCE IS A HIGHER THAN IT WAS YESTERDAY IN A FORECAST SOLUTION. AN UPPER LEVEL DISTURBANCE OVER SOUTHERN CALIFORNIA IS FORECAST TO EJECT NORTHEAST ACROSS COLORADO ON FRIDAY. EXPECT A FEW SHOWERS AND THUNDERSTORMS TO BE ONGOING THURSDAY EVENING AND DISSIPATING THROUGH MIDNIGHT OVER THE MOUNTAINS...WITH PERHAPS A FEW LINGERING SHOWERS OVER THE PALMER DIVIDE INTO NORTHEAST COLORADO INTO EARLY FRIDAY MORNING. FRIDAY HAS THE POTENTIAL TO BE INTERESTING. THE UPPER DISTURBANCE OVER ARIZONA WILL EJECT ACROSS COLORADO THROUGH FRIDAY EVENING. MODELS QUICK TO ADVECT MOISTURE NORTH ACROSS COLORADO...AND SHEAR LOOKS TO INCREASE TO AROUND 30 KTS OR SO BY THE AFTERNOON WITH MODEST INSTABILITY. EXPECT SHOWER AND THUNDERSTORM DEVELOPMENT BY MID MORNING FRIDAY ALONG THE CONTINENTAL DIVIDE...AND SPREADING EAST INTO THE I-25 CORRIDOR BY EARLY IN THE AFTERNOON. MODEL QPF FIELDS ARE INDICATING THAT HEAVY RAINFALL WILL BE POSSIBLE...ESPECIALLY OVER THE MOUNTAINS AND LOCATIONS OVER THE PALMER DIVIDE. FLASH FLOODING WILL BE POSSIBLE ON AREA BURN SCARS AND FLOOD PRONE AREAS FRIDAY AFTERNOON AND EVENING. SOME STORMS ACROSS THE PLAINS COULD BECOME STRONG...WITH SMALL HAIL AND GUSTY OUTFLOW WINDS ALSO POSSIBLE. MODELS IN GOOD AGREEMENT WITH THUNDERSTORMS SHIFTING EAST ACROSS THE PLAINS FRIDAY NIGHT WITH ALL ACTIVITY EXITING INTO KANSAS BY SATURDAY MORNING. SATURDAY WILL LIKELY BE A PRETTY QUIET DAY ACROSS SOUTHERN COLORADO GIVEN SUBSIDENCE BEHIND THE DEPARTING UPPER SYSTEM. A COUPLE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE OVER THE MOUNTAINS...BUT COVERAGE LOOKS TO BE MINIMAL. A BROAD TROUGH WILL PERSIST OVER THE WESTERN CONUS THROUGH THE MIDDLE OF NEXT WEEK WITH A COUPLE OF MORE DISTURBANCES MOVING ACROSS SOUTHERN COLORADO. THE NEXT ONE LOOKS TO MOVE ACROSS THE REGION ON SUNDAY. THIS WILL BRING ANOTHER UPTICK IN SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE STATE...WITH ACTIVITY STARTING OVER THE MOUNTAINS LATE SUNDAY MORNING AND SPREADING EAST THROUGH THE AFTERNOON AND EVENING. IN ADDITION...A COLD FRONT WILL MOVE SOUTH ACROSS THE PLAINS DURING THE AFTERNOON...TURNING LOW LEVEL FLOW UPSLOPE...WHICH WILL LIKELY AID PRECIPITATION DEVELOPMENT ACROSS THE PLAINS SUNDAY AFTERNOON AND EVENING. MODELS A BIT DIFFERENT ON THE ARRIVAL OF THE NEXT DISTURBANCE DROPPING ACROSS THE ROCKIES...WITH GFS HAS BEEN BRINGING IT THROUGH MONDAY EVENING...WITH THE ECMWF IS A BIT SLOWER ON TUESDAY. THIS WILL LIKELY LEAD TO ANOTHER ROUND OF DECENT PRECIPITATION FOR THE MOUNTAINS...AND SPREADING EAST INTO THE PLAINS SOMETIME IN THE MONDAY TO TUESDAY TIME FRAME. THIS SYSTEM LOOKS TO BE ACCOMPANIED BY A STRONG COLD FRONT WHICH SHOULD HELP THE PLAINS SEE ANOTHER SHOT FOR PRECIPITATION. MOZLEY && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 238 PM MDT WED AUG 20 2014 VFR CONDITIONS ARE EXPECTED AT KCOS...KPUB AND KALS TONIGHT THROUGH THURSDAY AFTERNOON. SOME THUNDERSTORMS WILL BE POSSIBLE IN THE VCNTY OF KCOS EARLY THIS EVENING...BUT MAY NOT MAKE IT INTO THE VCNTY OF KPUB AND KALS. THE MAIN THREATS WITH TSTMS WILL BE GUSTY WINDS. ON THURSDAY AFTERNOON SOME TSTMS ARE EXPECTED OVR THE HYR TRRN AND ONE OR TWO COULD MAKE IT INTO THE VCNTY OF KCOS. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...MOZLEY AVIATION...28
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
303 PM MDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 158 PM MDT WED AUG 20 2014 MIDLEVEL QUASIGEOSTROPHIC SUBSIDENCE /FROM RAP ANALYSES/ AND STABILITY /ACARS DATA/ IS KIND OF KEEPING CONVECTION AT BAY AS OF 20Z. THERE ARE A FEW ECHOES ON THE RADAR BUT THEY ARE RATHER WEAK AND SHORT-LIVED AT THIS TIME. THERE IS ALSO A VERY LOCALIZED AREA OF DOWNSLOPE FLOW OVER BOULDER COUNTY WHICH HAS LOWERED DEWPOINTS AND GPS-MEASURED PRECIPITABLE WATER VALUES THERE AND PRETTY MUCH SQUELCHED THE CONVECTION ALTOGETHER. THE HRRR HAS BEEN A BIT OVERZEALOUS WITH CONVECTION THAT IS SUPPOSED TO BE ONGOING AT THIS TIME AND INSISTS ON GENERATING QUITE A BIT OF ACTIVITY INTO THE EVENING HOURS OF THE PLAINS. THE GFS QPF FIELDS SUGGEST THE SAME THING WITH THE NAM AND ECMWF SEEMING A BIT MORE IN TOUCH WITH REALITY. IT SEEMS PRUDENT TO HOLD ONTO LOW POPS IN ALL AREAS THIS EVENING. TOMORROW DOES NOT APPEAR TO BE MUCH DIFFERENT THAN TODAY. QUASIGEOSTROPHIC FORECAST DIAGNOSTICS CONTINUE TO FORECAST SUBSIDENCE AND MODEL SOUNDINGS HAVE THE MIDLEVEL INSTABILITY LIKE TODAY. CONSEQUENTLY NOT EXPECTING ANY MORE CONVECTION THAT WHAT IS AROUND TODAY WITH THE PLAINS PERHAPS NOT SEEING ANYTHING. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 158 PM MDT WED AUG 20 2014 PRETTY GOOD MODEL AGREEMENT THROUGH THIS PERIOD...SHORTWAVES LIFT OUT OF THE MEAN TROUGH OVER THE WEST PASSING OVER COLORADO ON FRIDAY AND SUNDAY. A BIT MORE DISCREPANCY BY THE MIDDLE OF NEXT WEEK WITH THE PROSPECTS FOR THE TROUGH SHIFTING EAST...OR JUST ANOTHER SHORTWAVE MOVING AROUND IT. FOR THE FRIDAY WAVE...WE WILL BE FIGHTING THE SAME ISSUES WE HAVE HAD WITH SEVERAL OF THESE MOISTURE SURGES. WARM ADVECTION ALOFT WILL LIMIT INSTABILITY WHILE THE LOW LEVELS DO NOT MOISTEN MUCH...AND BY THE TIME THE BEST LIFT ARRIVES THERE IS EVEN A LITTLE COOLING AT THE SURFACE. STILL EXPECTING INCREASED SHOWER COVERAGE BUT MAINLY DUE TO LIFT IN THE ELEVATED MOIST LAYER. THIS CURRENTLY APPEARS TO BE PLAYED WELL WITH SCATTERED SHOWERS AND STORMS MAINLY FRIDAY AFTERNOON AND EVENING. I DID ADD A BIT MORE SHOWER ACTIVITY THURSDAY NIGHT AS SOME MODEL RUNS SHOW SOME CONVECTION MOVING OFF THE SOUTHERN COLORADO MOUNTAINS AND PERSISTING OVERNIGHT. ALSO SLOWED DOWN THE END OF THE SHOWERS EARLY SATURDAY IN LINE WITH MODEL TRENDS. FOR THE WEEKEND...DRIER AIR SHOULD TAKE AWAY THE INSTABILITY SO EXPECTING FAIRLY QUIET DAYS...STILL A LITTLE DIURNAL CONVECTION AND SOME LIFT FROM THE SECOND WAVE SUNDAY SHOULD HELP...BUT A RATHER UNFAVORABLE ENVIRONMENT. FOR EARLY NEXT WEEK...THERE APPEARS TO BE A WEAK FRONT DROPPING DOWN THE PLAINS IN THE MONDAY/TUESDAY TIME PERIOD RELATED TO SOME DEEPENING OF THE UPSTREAM TROUGH. THIS COULD BRING INCREASED LOW LEVEL MOISTURE...BUT ALSO SOME LOW LEVEL COOLING. SO ONCE AGAIN A TRADEOFF THAT RESULTS IN SOME INCREASED COVERAGE...BUT NOT NECESSARILY A LOT OF RAIN. THERE COULD BE AN OPTIMAL TIME ON TUESDAY OR WEDNESDAY IF THE TROUGH AXIS DOES SHIFT EASTWARD WHERE THERE IS A COMBINATION OF LIFT AND INSTABILITY. GFS WOULD SUGGEST DRYING BEHIND THE TROUGH BY WEDNESDAY...WHILE THE ECMWF HOLDING THE LONGWAVE TROUGH WEST OF US WOULD INDICATE NO COOLING ALOFT. SO OVERALL MINOR VARIATIONS ON AN ENVIRONMENT WHICH IS ONLY SLIGHTLY UNSTABLE IN THE AFTERNOONS...BUT IN THE MOIST PERIODS COULD ALLOW SOME WEAK CONVECTION WHENEVER THERE IS FORCING. BLEND OF THE MODEL CONSENSUS WITH THE PREVIOUS FORECAST LOOKS GOOD...I DID RAISE POPS A LITTLE ON TUESDAY AND WEDNESDAY ON THE PLAINS IN LINE WITH OUR NEIGHBORING OFFICES...WITH GREATER MOISTURE OUT THERE THAT SEEMS REASONABLE. && .AVIATION...(FOR THE TAFS THROUGH 00Z THURSDAY LATE AFTERNOON) ISSUED AT 158 PM MDT WED AUG 20 2014 IF PRESENT CONDITIONS CONTINUE IT LOOKS LIKE KAPA WOULD HAVE THE BEST /ALBEIT SMALL/ CHANCE OF SEEING SOME THUNDER THIS EVENING. THE 19Z HRRR MODEL IS STILL INSISTING ON CREATING A LOT OF THUNDERSTORM ACTIVITY WHICH IS LOOKING LESS AND LESS LIKELY AT THIS POINT. THUS KBJC AND KDEN MAY MAKE IT THROUGH THE EVENING WITHOUT ANY THUNDER. KBJC SHOULD SEE DOWNSLOPE FLOW/DRAINAGE WINDS THROUGH TONIGHT WITH SPEEDS IN THE 8-15KT RANGE. KAPA AND KDEN WILL HAVE LIGHTER WINDS THROUGHOUT THE PERIOD WITH DRAINAGE FLOW KICKING IN AFTER DARK. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ET LONG TERM...GIMMESTAD AVIATION...ET
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1121 PM MDT TUE AUG 19 2014 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 249 PM MDT TUE AUG 19 2014 WV SATELLITE IMAGERY TODAY SHOWING THE MONSOON MSTR PLUME OVR UT...BUT SLOWLY SHIFTING EASTWARD AS AN UPR LOW MOVES SOUTHWARD ALONG THE CA COAST. SCATTERED SHOWERS AND TSTMS ARE EXPECTED THIS EVENING OVR THE MTNS AND UPR ARKANSAS RIVER VALLEYS...WITH ISOLD ACTIVITY OVR THE SERN PLAINS. BY 03Z THE HRRR AND RAP SHOW LITTLE IF ANY PCPN OVR THE SERN PLAINS...WITH JUST SOME ISOLD PCPN OVR THE MTN AREAS. OVERNIGHT THAT UPR LOW WL MOVE OVR SRN CA AND THE MONSOON PLUME SHIFTS INTO WRN CO. AS A WX DISTURBANCE THE MSTR LIFTS NORTHEASTWARD ACRS NWRN CO...SOME PCPN WL PROBABLY CONTINUE THRU THE NIGHT ALONG THE CONTDVD...ESPECIALLY OVR THE CENTRAL CO MTNS WHICH WL BE CLOSEST TO THE DISTURBANCE AND BETTER MSTR. ON WED THE UPR LOW IS EXPECTED TO REMAIN OVR SRN CA. THE BEST MSTR GOES NORTH OF THE AREA WITH THAT DISTURBANCE...AND MODELS ARE MAINLY SHOWING SPOTTY PCPN FOR THE FORECAST AREA. WILL KEEP SCT POPS OVR THE MTNS AREAS FOR WED AFTERNOON AND ISOLD POPS OVR THE SAN LUIS VALLEY AND I-25 CORRIDOR. HIGH TEMPS ON WED SHOULD GENERALLY BE AROUND TO A LITTLE ABOVE AVERAGE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 249 PM MDT TUE AUG 19 2014 THE UPPER LEVEL PATTERN IS FORECAST TO FEATURE A BROAD UPPER LEVEL TROUGH OVER THE NORTHWEST TO NORTH-CENTRAL CONUS AND A HIGH PRESSURE CENTER OVER THE SOUTHEAST STATES. THIS WILL PUT SOUTHERN COLORADO UNDER SOUTHWESTERLY FLOW FOR MUCH OF THE EXTENDED. THERE ARE MODEL DIFFERENCES IN HOW THEY WANT TO HANDLE UPPER LEVEL DISTURBANCES IN THE FLOW...AND ENSEMBLES DEVELOP HIGH SPREADS BY THIS WEEKEND LEADING TO LOWER CONFIDENCE IN THE LAST COUPLE OF DAYS OF THE EXTENDED PERIOD. THE GFS HAS REMAINED CONSISTENT FROM RUN TO RUN WITH AN UPPER LEVEL LOW OVER SOUTHERN CALIFORNIA AND EJECTING IT NORTHEAST ACROSS COLORADO ON THURSDAY NIGHT INTO FRIDAY. THE LATEST ECMWF IS MORE IN LINE WITH THIS SOLUTION...HOWEVER IS ABOUT 24 HOURS SLOWER IN EJECTING THE SYSTEM OUT. THE BIGGEST FORECAST CHANGE FOR THE GFS IS WHERE THE SYSTEM DEVELOPS CONVECTION ON THURSDAY. EXPECT ONGOING CONVECTION ACROSS THE MOUNTAINS WEDNESDAY EVENING WITH MODELS BRINGING BAND EAST ACROSS THE PLAINS THROUGH THE OVERNIGHT HOURS AS A WEAK DISTURBANCE LIFTS NORTHEAST. BY THURSDAY MORNING...THE LOW PRESSURE CENTER OVER SOUTHERN CALIFORNIA IS FORECAST TO OPEN UP AND LIFT NORTHEAST ACROSS COLORADO. THUNDERSTORMS ARE FORECAST TO DEVELOP OVER THE MOUNTAINS BY LATE THURSDAY MORNING. THUNDERSTORMS DEVELOPMENT IS THEN EXPECTED EASTWARD ACROSS THE PALMER DIVIDE THROUGH THE AFTERNOON AND EVENING HOURS. THE PREVIOUS RUN OF THE GFS HAD THIS THUNDERSTORM DEVELOPMENT FURTHER SOUTH OVER SOUTHERN COLORADO...SO WHERE THIS DISTURBANCE EJECTS WILL PLAY A ROLE IN WHAT AREAS SEEN THE POTENTIAL FOR HEAVIER PRECIPITATION. THE ECMWF AND NAM SOLUTIONS ARE A BIT SLOWER WITH THIS SYSTEM...WITH IT EJECTING ACROSS SOUTHERN COLORADO ON FRIDAY AFTERNOON. IF THIS IS THE CASE...THURSDAYS CONVECTION WILL LIKELY REMAIN TIED TO THE TERRAIN AND PALMER DIVIDE...WITH NOT MUCH EXPECTED ON THE PLAINS. THE HEAVY PRECIPITATION CHANCES WOULD THEN FOCUS ON FRIDAY AFTERNOON AND NIGHT...WITH HEAVY RAINFALL AND THE POTENTIAL FOR FLASH FLOODING. THE IMPORTANT THING TO REMEMBER...IS THAT SOME TIME BETWEEN THURSDAY AND FRIDAY NIGHT...SOUTHERN COLORADO WILL LIKELY SEE A PERIOD OF WIDESPREAD HEAVIER RAINFALL. A BROAD TOUGH IS FORECAST TO REMAIN ENTRENCHED ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS SATURDAY THROUGH TUESDAY. THE MAIN FORECAST ISSUE WILL BE HOW DEEP THE TROUGH GETS. THE GFS SOLUTIONS DIGS IT THE FURTHEST SOUTH...WITH CONTINUED ACTIVE WEATHER ACROSS THE AREA...WHILE THE ECMWF IS KEEP MOST OF THE ENERGY CONFINED TO OUR NORTH WITH LESS CHANCES FOR PRECIPITATION. A COLD FRONT IS FORECAST TO DROP SOUTH ACROSS THE PLAINS ON SUNDAY WHICH MAY BE THE BEST OPPORTUNITY FOR WIDESPREAD PRECIPITATION ACROSS THE AREA. OTHERWISE...CONVECTION WILL LIKELY REMAIN OVER THE MOUNTAINS WITH LIMITED ACTIVITY OVER THE PLAINS. MOZLEY && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1121 PM MDT TUE AUG 19 2014 MAINLY VFR CONDITIONS EXPECTED AT COS...PUB AND ALS OVER THE NEXT 24 HOURS...WITH ISOLATED TO SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS REMAINING IN THE FORECAST. BEST COVERAGE OF STORMS TO REMAIN OVER AND NEAR THE HIGHER TERRAIN AND WILL KEEP VCTS AFT 20Z IN TAFS AT THIS TIME. GUSTY WINDS TO 45 MPH AND BRIEF MODERATE TO HEAVY RAINFALL WILL BE POSSIBLE WITH STORMS. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...MOZLEY AVIATION...MW
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1034 PM MDT TUE AUG 19 2014 .UPDATE... ISSUED AT 947 PM MDT TUE AUG 19 2014 MAINLY STRATIFORM PRECIPITATION CONTINUES THIS EVENING WITH A FEW RUMBLES OF THUNDER THANKS TO EMBEDDED CONVECTION. LATEST NAM12 RUN NOT INTIALIZING WELL...NOR IS THE GFS WITH BOTH SHOWING WIDESPREAD AND HEAVY PRECIP OVERNIGHT WHILE HRRR IS CAPTURING PRECIP IN OUR AREA PRETTY WELL. HRRR ALSO SHOWS SOME SHOWERY ACTIVITY CONTINUING OVERNIGHT BUT COVERAGE IS ISOLATED AT BEST. LOOKING UPSTREAM...RADAR MOSAIC SHOWING CONVECTION OVER EXTREME WRN UT/ERN NV WITH NOT MUCH IN BETWEEN. IR IMAGERY IS ALSO SHOWING WARMING CLOUD TOPS ACROSS OUR CWA INDICATING STRONGEST CONVECTION HAVING ENDED. DO HAVE SOME CONCERN THAT UPPER LEVEL JET MOVING OVERHEAD MAY FIRE OFF MORE CONVECTION OVERNIGHT BUT WITH DIVERGENCE WEAKENING...WILL GO WITH MORE SCT TO ISOLD COVERAGE. && .SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT) ISSUED AT 344 PM MDT TUE AUG 19 2014 CURRENT IR SATELLITE SHOWS TWO PRECIPITATION HOT SPOTS - ONE WEST OF VERNAL AND THE OTHER DOWN BY THE FOUR CORNERS. RADAR RETURNS SHOW THE OUTER PERIPHERY OF THE ENHANCEMENT AT BLANDING UTAH AT 315PM. THIS RAIN WILL EXPAND TO THE NORTHEAST THROUGH THE LATE AFTERNOON AND EVENING AS PRECIPITABLE WATER VALUES REACH THEIR MAXIMUM OF ONE INCH TO 1.2 INCHES ACROSS THE REGION. A SERIES OF H5 VORT MAXES ALONG WITH AN APPROACHING H3 50KT JET WILL MOVE INTO THE AREA THIS EVENING...HELPING TO SUSTAIN SHOWERS AND OCCASIONAL EMBEDDED THUNDERSTORMS. STORM MOTION STILL LOOKS TO BE 20 TO 30 KTS WITH MINIMAL TRAINING OCCURRING SO FAR. SOME SUBSIDENCE OVER THE REGION TOMORROW WILL HINDER HIGH LIKELIHOOD OF SHOWERS AND THUNDERSTORMS...HOWEVER FORECAST CIN IS LOW OR NONEXISTENT BY THE AFTERNOON...AND AMPLE MOISTURE AND BREAKS IN THE CLOUDS WILL BE IN PLACE TO INITIATE ISOLATED/SCATTERED CONVECTION IN THE AFTERNOON. STEERING FLOW WILL SLOW BY MIDDAY TO 10 TO 15 KTS. EXPECTING ACTIVITY TO OCCUR EARLIER IN THE AFTERNOON AND TAPER OFF FOR THE MOST PART IN THE EVENING. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 344 PM MDT TUE AUG 19 2014 WEATHER THE LAST HALF OF THE WEEK DEPENDS LARGELY ON THE UPPER LOW CURRENTLY DROPPING SOUTH ALONG THE CA COAST. MODELS CONTINUE TO HAVE SOME DIFFICULTY HANDLING THIS LOW. THE GFS REMAINS THE MOST PROGRESSIVE...SWINGING IT IN INLAND ACROSS SRN CA THU AND UP THROUGH ERN UT/WRN CO THU NIGHT. THE NAM AND ECMWF ARE SLOWER BY ABOUT 12-24 HRS ON A TRACK A LITTLE FARTHER SOUTH. NUDGED POPS UPWARD THU-FRI BUT REMAINED CONSERVATIVE DUE TO THE TIMING DIFFERENCES. SOME STORMS COULD BE RATHER STRONG THU-FRI GIVEN THAT THE DEEP LAYER Q-G FORCING MAXIMA MOVES ACROSS THE AREA...AND 0-6KM VERTICAL WIND SHEAR INCREASES WITH TROUGH PASSAGE...REGARDLESS OF MODEL. MODELS ALSO HINT AT BRIEF ENTRAINMENT OF SOME MOISTURE FROM TROPICAL STORM LOWELL...REFLECTED MORE IN THE 320K/325K ISENTROPIC SURFACE HUMIDITY THAN PRECIPITABLE WATER FORECAST. CONCURRENTLY...SHORTWAVE ENERGY SHARPENS AN UPPER TROUGH OVER THE PAC NW AND NRN ROCKIES LATE IN THE WEEK. THIS TROUGH THEN SLOWLY MIGRATES EASTWARD TO THE NORTHERN PLAINS AND SOUTHERN CANADA BY MONDAY AFTERNOON. THIS SHOULD RESULT IN SOMEWHAT DRIER WESTERLY FLOW ACROSS OUR AREA BY SUNDAY FOR A DOWNTURN IN SHOWER AND STORM ACTIVITY THIS WEEKEND THROUGH EARLY NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 947 PM MDT TUE AUG 19 2014 -RA BEING REPORTED ALONG AND N OF I-70 THIS EVENING WITH KRIL COMING IN WITH SOME MVFR CIGS WHILE REMAINING TAF SITES REPORTING CIGS AROUND 6 TO 7K. AS THIS PRECIP CONTINUES SHIFTING TO THE NE...VFR CONDITIONS ARE EXPECTED WITH BKN TO OVC SKIES. LATEST GUIDANCE SHOWING MORE OF A DOWN DAY TOMORROW WITH SOME ISOLD CONVECTION TO CONTEND WITH ACROSS THE CWA WITH MTN TAF SITES AND POSSIBLY SOME VALLEY SITES SEEING SOME -RA...VCTS...OR A PASSING -TSRA. && .HYDROLOGY... ISSUED AT 344 PM MDT TUE AUG 19 2014 MONSOONAL MOISTURE IS RETURNING THIS EVENING AS AN UPPER LEVEL LOW OVER CALIFORNIA PULLS DEEP SUBTROPICAL MOISTURE INTO THE REGION. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE FROM WEST TO EAST THIS EVENING...PEAKING THIS EVENING THEN CONTINUING OVERNIGHT INTO WEDNESDAY MORNING. EXPECT SOME SMALL STREAM AND ARROYO FLOOD ISSUES BY WEDNESDAY MORNING IN THE USUAL PROBLEM AREAS. HOWEVER...DO NOT EXPECT SUFFICIENTLY WIDESPREAD COVERAGE OF TORRENTIAL DOWNPOURS TO WARRANT FLASH FLOOD WATCH. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...TGR SHORT TERM...JAM LONG TERM...JAD AVIATION...TGR HYDROLOGY...NL/JAM
AREA FORECAST DISCUSSION
NWS TAUNTON MA
958 PM EDT THU AUG 21 2014 .SYNOPSIS... SHOWERS CONTINUING ACROSS WESTERN NEW ENGLAND OVERNIGHT INTO FRIDAY...DISSOLVING SOUTHWEST AS HIGH PRESSURE BUILDS IN FROM THE NORTH. HIGH PRESSURE OUT OF THE MARITIMES WILL BRING DRIER AND COOLER CONDITIONS THIS WEEKEND. MILDER TEMPERATURES WILL RETURN EARLY NEXT WEEK. UNSETTLED CONDITIONS MAY RETURN LATE WEDNESDAY OR NEXT THURSDAY AS A FRONT MAY APPROACH OUT OF QUEBEC. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 10 PM UPDATE... WV IMAGERY SHOWS WEAKENED UPPER LVL CUTOFF VORTMAX NOW SLIDING SE THROUGH NY INTO PA/NJ THIS EVENING. LATEST RAP ALSO SHOWS THAT AXIS OF LEFTOVER INSTABILITY RESIDES TO THE W AS WELL. HENCE WHY MUCH OF THE CONVECTIVE ACTIVITY IS TAKING ON A MORE N-S PROPAGATION THIS EVENING AND WHY ONLY LEFTOVER CONVECTION IN THE FORM OF LIGHT-MOD -SHRA ARE MAKING IT/S WAY INTO THE WRN ZONES. FEEL THIS WILL CONTINUE TO BE THE TREND MUCH OF THE NIGHT...ALTHOUGH EXPECT THAT THE BULK OF THE STRONGER CONVECTION IS LIKELY TO WEAKEN WITH THE LOSS OF HEATING. ELSEWHERE...FURTHER E...SPOTTY -SHRA CONTINUE TO FORM AHEAD OF THE VORTMAX ALONG AN AXIS OF 30+ K-INDEX VALUES SUGGESTIVE OF MODERATE COLUMN MOISTURE IN THE LOW-MID LVLS AND JUST ENOUGH CONDITIONAL INSTABILITY TO SUPPORT THE LIFT PROVIDED BY THE APPROACHING WAVE. THESE ARE LIKELY TO CONTINUE FORMING IN-SITU ACROSS THE REGION...SO AN AXIS OF HIGH CHANCE TO LOW LIKELY POPS WILL BE USED. SOME OF THESE ARE LIKELY TO HOLD TOGETHER INTO THE PROVIDENCE-BOSTON CORRIDOR AS WELL. PREVIOUS DISCUSSION... TONIGHT... LOW TRANSITIONS AS AN OPEN WAVE LOW TOWARDS THE SE. ACCOMPANYING MAIN CRUX OF ENERGY YIELDS ASCENT OF AVAILABLE MOISTURE FUELED BY A SW-PLUME OF HIGHER THETA-E AIR WRAPPING AHEAD OF THE LOW /1.5 PWAT AIRMASS/ CONVERGING AGAINST HIGH PRESSURE AND DRY AIR BUILDING SW BELOW H8. THIS YIELDS NW-SE ORIENTED AREAS OF F-GEN FORCING WITHIN THE LOW-LEVELS THAT WILL LIKELY PARENT WITH MID- LEVEL FORCING. A CONSENSUS WEIGHTING OF MODEL GUIDANCE PUTS THE LIKELIHOOD OF SHOWERS TOWARDS THE W/SW FORECAST ZONE WHICH WOULD BE EXPECTED BUT CAN NOT RULE OUT OF CHANCE OF SHOWERS ELSEWHERE. ONLY THE IMMEDIATE E/SE MAY BE SPARED OF WET WEATHER...BUT AM NOT HOLDING MY BREATH. LOW CONFIDENCE OF THUNDER WITH THE STABLE ENVIRONMENT. WILL NEED TO MONITOR FOR FOG AND LOW CLOUDS. HIGHEST CONFIDENCE IS IN AREAS OF STRONG LOW-LEVEL CONVERGENCE AND SHOWERS... ESPECIALLY ACROSS THE HIGHER TERRAIN. YET WITH E-ONSHORE FLOW DRIVING IN HIGHER DEWPOINT AIR...ALONG WITH THE GREATER CAPACITY FOR AREAS TO RADIATE EFFICIENTLY THE LAST COUPLE OF NIGHTS...FOG AND LOW CLOUDS MAY BE POSSIBLE FOR E/SE PORTIONS OF NEW ENGLAND. INCREASING CLOUDS FROM THE W MAY COMPLICATE THE MATTER. WILL GO WITH LOWS AROUND THE UPPER-50S TO LOW-60S WITH THE COOL SPOTS TO THE N/W WHICH BARELY SAW ANY SUN...AND THE E/SE IMMEDIATE INTERIOR. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY... WITH THE LOW SWUNG SE OF THE REGION...CUTOFF ENERGY WRAPS REARWARD AND SE INTO THE REGION INVOKING A HANGING TROUGH. RISING HEIGHTS IN WAKE OF THE TROUGH ALLOW FOR ENHANCED RIDGING OF HIGH PRESSURE SW AHEAD OF WHICH F-GEN FORCING IS MAXIMIZED WITHIN THE LOW-LEVELS. PARENTING WITH MID-LEVEL ASCENT PER CUTOFF ENERGY...THERE IS THE LIKELIHOOD FOR CONTINUED SHOWERY WEATHER OVER SW PORTIONS OF NEW ENGLAND. WILL HOLD WITH LIKELY POPS ACROSS FAR W/SW PORTIONS OF THE FORECAST AREA BENEATH AN ABUNDANCE OF CLOUDS. AM NOT GOING TO GET SPECIFIC WITH THE FORECAST POPS BUT RATHER BROAD BRUSH AN AREA WHERE THERE IS HIGHEST CONFIDENCE. CHANCE TO SLIGHT CHANCE POPS E. COMBINATION OF CLOUDS AND RAIN COULD MAKE FOR A VERY CHILL DAY ESPECIALLY FOR MID- TO LATE-AUGUST. THE DREARY WEATHER COULD YIELD HIGHS AROUND THE LOW- TO MID-60S FOR THE S/W...WARMER E WHERE THE GREATER CHANCE OF SEEING SOME SUNSHINE YET ONLY INTO THE UPPER-60S WITH THE BRISK ONSHORE E-FLOW SURGING INTO INTERIOR NEW ENGLAND. FRIDAY NIGHT... ACTIVITY SHOULD DIMINISH WITH SUBSIDENCE AND DRY AIR BUILDING SW AS HEIGHTS RISE IN RESPONSE TO THE HANGING TROUGH SWINGING S/E. LOW- LEVEL F-GEN FORCING AND MID-LEVEL FORCING SHOULD CONTINUE TO PUSH SW INTO NY/PA AHEAD OF CONTINUED RIDGE ENHANCEMENT. WHILE CONSENSUS WEIGHTING OF MODEL GUIDANCE YIELDS A SLIGHT CHANCE OF SHOWERS FOR S/W PORTIONS OF THE FORECAST AREA...THE LONG E-FETCH OFF THE WATERS LIKELY RESULTING IN MOISTURE POOLING WITHIN THE LOW- LEVELS COULD RESULT IN LOW CLOUDS AND FOG...PERHAPS EVEN DRIZZLE AS THE FLOW UNDERGOES OROGRAPHIC LIFT ALONG THE E-SHORELINE. A TOUGH FORECAST AND A LIKELY COOL AND DREARY NIGHT WITH LOWS GETTING DOWN AROUND THE MID-50S. WITH DEWPOINTS AT SIMILAR VALUES... ANTICIPATING A PLETHORA OF PATCHY DENSE FOG WHERE THE E-FLOW IS LIGHT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THIS PERIOD * MILDER TEMPERATURES WILL RETURN MONDAY AND TUESDAY AS RIDGE TRIES TO BUILD EAST * TIMING OF APPROACHING FRONT BY LATE NEXT WEEK REMAINS UNCERTAIN BLOCKING UPPER LEVEL PATTERN LOOKS TO REMAIN IN PLACE ACROSS NORTH AMERICA AS H5 CUTOFF LOW PRES REMAINS PERSISTENT S OF GREENLAND THROUGH MOST IF NOT ALL OF THE LONG TERM PERIOD. SOME QUESTIONS DO COME INTO PLAY AS THE NORTHERN STREAM UPPER FLOW TRIES TO RECONFIGURE EARLY NEXT WEEK. NW FLOW TRIES TO FLATTEN OUT LATER THIS WEEKEND...THEN UPPER LEVEL RIDGING APPEARS TO BUILD IN BRIEFLY AROUND MONDAY OR TUESDAY. OPERATIONAL MODEL RUN DIFFERENCES MAY BE RESOLVING...BUT STILL SOME TIMING ISSUES CONTINUE LATE NEXT WEEK. THIS LENDS TO LOWER FORECAST CONFIDENCE BEYOND TUESDAY. DETAILS... SATURDAY AND SUNDAY... EXPECT HIGH PRES RIDGING TO CONTINUE TO NOSE IN FROM THE MARITIMES. THE ORIENTATION OF THIS RIDGE WILL KEEP COOL ONSHORE WINDS. SEVERAL OPERATIONAL MODEL SOLUTIONS...MAINLY THE 12Z GFS/ECMWF...TRY TO WORK CLOUDS AND SOME LIGHT PRECIP OFF THE OCEAN DURING SAT WITH LONG FETCH OFF THE GULF OF MAINE. CAN NOT RULE OUT ISOLD SHOWERS THAT MAY MOVE ONSHORE SATURDAY MORNING THEN PUSH W. COULD EVEN SEE SOME LIGHT DRIZZLE AROUND SUNRISE ALONG THE IMMEDIATE COAST. HAVE MENTIONED ONLY SLIGHT CHANCE POPS AT THIS POINT...THOUGH...BECAUSE OF UNCERTAINTY OF HOW MUCH MOISTURE WILL BE REALIZED. ONE CERTAINTY THOUGH IS THAT COOLER THAN NORMAL TEMPS WILL REMAIN WITH THE ONSHORE WINDS THROUGH THE WEEKEND. MONDAY AND TUESDAY... LOOKS LIKE THE MARITIMES RIDGE AXIS TRIES TO PUSH OFFSHORE AS H5 RIDGE PUSHES SE OUT OF ONTARIO AND THE GREAT LAKES AND ACTUALLY BUILDS INTO QUEBEC...A SET UP THAT HAS BEEN RARE THIS SUMMER. WILL REMAIN DRY BUT LOOKS LIKE MILDER TEMPS ON THE HORIZON AS WINDS BACK AROUND TO W AND SW. TEMPS LOOK BE CLOSE TO SEASONAL NORMS FOR LATE AUGUST...THOUGH WILL REMAIN A BIT COOLER ALONG THE S COAST. HUMIDITY WILL ALSO START TO INCREASE DURING TUESDAY. WEDNESDAY AND THURSDAY... WHILE THE LAST SEVERAL ECMWF OP RUNS HAVE BEEN MUCH FASTER THAN THE COUNTERPART GFS...THE 12Z RUN LOOKS MUCH CLOSER WITH ITS SOLUTION IN KEEPING RIDGING ACROSS MOST OF THE EASTERN SEABOARD. ONE BIG FLY IN THE OINTMENT IS THE POSSIBILITY OF A SYSTEM THAT WILL TRY TO MAKE THE TURN AROUND THE SUBTROPICAL RIDGE OFFSHORE...BUT THAT IS HIGHLY UNCERTAIN. WEAK COLD FRONT MAY STILL TRY TO WORK OUT OF QUEBEC LAST WED OR THU...THEN COULD STALL SOMEWHERE ACROSS THE REGION. STILL A TOUGH CALL. ALSO...DEPENDING UPON AVAILABLE MOISTURE AND INSTABILITY...MIGHT SEE SOME SHOWERS AND/OR THUNDERSTORMS IN VICINITY OF THE FRONT. LEANED TOWARD A BLEND OF THE 12Z GFS RUN ALONG WITH GFS/EC ENSEMBLES FOR THIS PORTION OF THE FORECAST. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH FRIDAY NIGHT...MODERATE CONFIDENCE. THROUGH THE OVERNIGHT... EXPECT MAINLY VFR ACROSS E MA INTO RI EARLY. LIGHT ONSHORE FLOW WILL BRING PATCHY FOG...WHILE AREA OF SHOWERS OVER NY STATE WILL MOVE E. WILL SEE CONDITIONS LOWER TO AREAS OF MVFR-IFR. MAY SEE BRIEF PATCHES OF DENSE FOG FROM 06Z-12Z ACROSS THE NORMALLY PRONE VALLEY LOCATIONS. INTO THE FRIDAY INTO FRIDAY NIGHT PERIOD...ANTICIPATING LOW-END VFR CLOUDS MIXED IN WITH MVFR AND SHOWERS TO THE S/W ESPECIALLY ACROSS THE HIGH TERRAIN. E-WINDS CONTINUING WITH A LONG FETCH OFF THE WATERS. TRANSITIONING INTO EVENING...WHILE SHOWERS CONCLUDE... A MAJORITY OF THE TERMINALS MAY BECOME SOCKED IN WITH LOW-CLOUDS AND/OR DENSE FOG. LIKELY TO SEE -DZ ALONG THE E-SHORE TERMINALS TOWARDS SATURDAY MORNING. KBOS TERMINAL...MODERATE CONFIDENCE. WILL HOLD LOW-END VFR FOR A MAJORITY OF THE FORECAST. COULD SEE CONDITIONS GRADUALLY LOWER FRIDAY INTO FRIDAY NIGHT. E-FLOW PERSISTING THROUGHOUT AND INCREASING TOWARDS THE END OF THE PERIOD...THUS LENDING TO CONFIDENCE MORE SO OF MVFR-IFR LOW-CLOUDS OVER DENSE FOG WITH -DZ. KBDL TERMINAL...MODERATE CONFIDENCE. CONDITIONS ANTICIPATED TO LOWER INTO EVENING WITH INCREASING -SHRA CHANCES...MAINLY AFTER MIDNIGHT. MAY REMAIN SOCKED IN AROUND MVFR TO AT LEAST MID MORNING SATURDAY. OUTLOOK...SATURDAY THROUGH TUESDAY... HIGH CONFIDENCE FOR VFR. LOW PROBABILITY OF PATCHY FOG WITH BRIEF LOCAL MVFR-IFR CONDITIONS EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH FRIDAY...MODERATE CONFIDENCE. NE-WINDS INCREASING IN RESPONSE TO INTERIOR LOW PRESSURE SHIFTING SE ACROSS THE WATERS WITH SOME MILD STRENGTHENING AS HIGH PRESSURE BUILDS IN FROM THE N. SUBSEQUENT PRESSURE-GRADIENT MAY YIELD SOME DECENT FETCH WITH GUSTS UP TO 20 KTS TO CAUSE SEAS TO RISE...BUT WILL HOLD AT 4 FEET. FEEL BRISK WINDS WILL DIMINISH FOG POTENTIAL YET LOW CLOUDS AND SHOWERS MAY BE AN ISSUE FOR AREAS TOWARDS THE SW. OUTLOOK...SATURDAY THROUGH TUESDAY... HIGH CONFIDENCE. EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA THROUGH THE PERIOD. THERE IS A CHANCE THAT E SWELLS COULD BUILD CLOSE TO 5 FT ON THE OUTER WATERS THIS WEEKEND WITH LONG E FETCH...EVEN WITH WIND SPEEDS LESS THAN 15 KT. MAY SEE PATCHY OVERNIGHT FOG REDUCING VISIBILITIES EACH NIGHT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...SIPPRELL/EVT NEAR TERM...DOODY/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...EVT AVIATION...SIPPRELL/EVT MARINE...SIPPRELL/EVT
AREA FORECAST DISCUSSION
NWS TAUNTON MA
703 PM EDT WED AUG 20 2014 .SYNOPSIS... WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL BOUNDARY SWEEPING SOUTH OUT OF CANADA. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 7 PM UPDATE... DIURNAL CU DISSIPATING IN EASTERN NEW ENG...BUT EXPECT AN EXPANSION OF SC IN THE WEST TONIGHT AS LOW LEVEL MOISTURE INCREASES FROM THE WEST. ALSO MONITORING LOW CLOUDS SE OF ACK WHICH IS EXPECTED TO MOVE ACROSS THE ISLANDS AND OUTER CAPE OVERNIGHT. STILL UNCERTAINTY AS TO HOW FAR NORTH AND WEST OCEAN SHOWERS WILL GET ASSOCD WITH AREA OF CONVERGENCE OF HIGHER THETAE AIR. 18Z NAM/GFS HAVE BACKED OFF AND SO WE LOWERED POPS TO CHC CATEGORY FOR OUTER CAPE AND ACK AS THIS IS A LOW CONFIDENCE FORECAST. PREVIOUS DISCUSSION... HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS... TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND POSSIBLY SE MA. TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER- LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE... BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER CHANCE POPS ONLY INTO THE CT-VALLEY. TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. THE SETUP IS ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE TO GO HIGH CATEGORICAL POPS. THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING. ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE POSSIBILITY OF PATCHY GROUND FOG. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THURSDAY INTO THURSDAY NIGHT... CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC TOWARDS THE BETTER THERMAL-INSTABILITY AXIS. SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE AND DRY...LIKELY TO ERODE ACTIVITY S AND W. AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW BUILDING RIDGE. WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID- TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM * UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING FRONT. MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE TROUGH JUST OFFSHORE LONGER AND LONGER. COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF... THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION OF ANYTHING LIKELY TO OCCUR. THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. VFR. LIGHT/VRB WINDS OVERNIGHT BEFORE PREVAILING E/SE THURSDAY INTO THURSDAY NIGHT. LOW-END VFR CIGS SLOWLY BUILDING E ALONG WITH -RA CHANCES TOWARDS IJD-ORH-AFN. WILL ALSO NEED TO WATCH SE MA FOR POTENTIAL +RA AND MVFR-IFR IMPACTS BEGINNING AFTER MIDNIGHT INTO THU MORNING. CONDITIONS BEGIN TO IMPROVE CLOSER TO FRIDAY MORNING. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E/SE FLOW PREVAILS. EXPECT CONDITIONS NO LOWER THAN LOW-END VFR CIGS. -RA CHANCES MINIMAL. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE THOUGH LOW-CONFIDENCE AT THIS TIME. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY MVFR/IFR FOG EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25 KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3 TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION. LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...RLG/SIPPRELL NEAR TERM...KJC/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...RLG AVIATION...KJC/RLG/SIPPRELL MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS TAUNTON MA
409 PM EDT WED AUG 20 2014 .SYNOPSIS... WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL BOUNDARY SWEEPING SOUTH OUT OF CANADA. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... INTO THIS EVENING... DIURNAL CUMULUS WILL DISSIPATE WITH THE CONCLUSION OF DAYTIME MIXING. HIGH CLOUDS WILL LIKELY BEGIN TO FILTER INTO THE REGION FROM THE CONVECTION ONGOING OVER NY/PA. ALSO MONITORING THE AREA SE OF NANTUCKET WHERE LOW-LEVEL CONVERGENCE OF HIGHER THETA-E AIR IS LIKELY ONGOING LENDING TO SOME LOW CLOUDS. EXPECT THIS ACTIVITY TO FILTER ACROSS THE ISLAND TOWARDS THE CAPE AS WE GO INTO THE EVENING HOURS. WILL SEE WINDS BECOME LIGHT AND VARIABLE. TONIGHT... HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS... TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND POSSIBLY SE MA. TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER- LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE... BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER CHANCE POPS ONLY INTO THE CT-VALLEY. TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. SLIGHT CHANCE OF THUNDER WITH AT LEAST A LITTLE INSTABILITY PRESENT. THE SETUP IS ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE TO GO HIGH CATEGORICAL POPS. THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING. ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE POSSIBILITY OF PATCHY GROUND FOG. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THURSDAY INTO THURSDAY NIGHT... CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC TOWARDS THE BETTER THERMAL-INSTABILITY AXIS. SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE AND DRY...LIKELY TO ERODE ACTIVITY S AND W. AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW BUILDING RIDGE. WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID- TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM * UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING FRONT. MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE TROUGH JUST OFFSHORE LONGER AND LONGER. COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF... THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION OF ANYTHING LIKELY TO OCCUR. THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. VFR. SEA-BREEZES CONTINUE...BECOMING LIGHT/VRB OVERNIGHT BEFORE PREVAILING E/SE THURSDAY INTO THURSDAY NIGHT. LOW-END VFR CIGS SLOWLY BUILDING E ALONG WITH -RA CHANCES TOWARDS IJD-ORH-AFN. WILL ALSO NEED TO WATCH SE MA FOR POTENTIAL +RA AND MVFR-IFR IMPACTS BEGINNING AFTER MIDNIGHT THURSDAY. CONDITIONS BEGIN TO IMPROVE CLOSER TO FRIDAY MORNING. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E/SE FLOW PREVAILS. EXPECT CONDITIONS NO LOWER THAN LOW-END VFR CIGS. -RA CHANCES MINIMAL. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE THOUGH LOW-CONFIDENCE AT THIS TIME. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY MVFR/IFR FOG EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25 KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3 TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION. LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...RLG/SIPPRELL NEAR TERM...SIPPRELL SHORT TERM...SIPPRELL LONG TERM...RLG AVIATION...RLG/SIPPRELL MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS MIAMI FL
851 PM EDT THU AUG 21 2014 .UPDATE... BULK OF EVENING CONVECTION OVER CENTRAL FLORIDA SHOULD STAY AWAY FROM SOUTHERN FLORIDA EXCEPT FOR ONE OR TWO LEFTOVER SHOWERS WEST OF LAKE OKEECHOBEE. EASTERLY FLOW WELL ESTABLISHED ACROSS THE AREA, ALBEIT WEAK AT LESS THAN 10 KNOTS AS PER LATEST MIAMI SOUNDING. MOSTLY DRY NIGHT EXPECTED, EXCEPT FOR NEAR THE EAST COAST WHERE A FEW SHOWERS OR AN ISOLATED THUNDERSTORM MAY DEVELOP IN EAST FLOW. THE LATEST HRRR MODEL RUN (22Z) SHOWS A DECENT AMOUNT OF PRECIP AFFECTING MIAMI-DADE AND BROWARD COUNTIES AFTER 3 AM, BUT THIS SEEMS UNREASONABLE BASED ON GENERAL LACK OF FORCING AND NOT MUCH IN THE WAY OF CURRENT PRECIP UPSTREAM OVER NW BAHAMAS. THEREFORE WILL LEAVE THE SLIGHT CHANCE POPS FOR THE EAST COAST AS IS. /MOLLEDA && .AVIATION... LIGHT EAST WINDS AND VFR CONDITIONS OVERNIGHT, WITH THE EXCEPTION OF A FEW SHOWERS/ISOLATED TSTMS NEAR EAST COAST BETWEEN 09Z-12Z AND AGAIN FROM ABOUT 15Z-17Z. EAST WINDS ONCE AGAIN ON FRIDAY, EXCEPT LIGHTER THAN TODAY. THIS WILL FOCUS MOST OF AFTERNOON TSTMS IN THE INTERIOR, WITH GENERAL MOTION TOWARDS THE GULF COAST DURING THE MID/LATE AFTERNOON. FOR NOW HAVE VCTS FRIDAY AFTERNOON FOR NAPLES AND THIS COULD BE INCREASED TO TEMPO IN SUBSEQUENT FORECASTS. VCSH FOR EAST COAST SHOULD COVER AFOREMENTIONED NIGHT/MORNING SHOWERS. /MOLLEDA && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 91 77 90 / 10 30 0 10 FORT LAUDERDALE 81 91 80 91 / 20 20 0 10 MIAMI 80 91 80 91 / 10 20 0 20 NAPLES 76 91 79 91 / 10 40 20 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
1031 AM EDT WED AUG 20 2014 .UPDATE... RIDGE OF HIGH PRESSURE STRETCHES ACROSS THE COUNTY WARNING AREA. PRECIPITABLE WATER VALUES HAVE JUMPED UP TO NEAR NORMAL TODAY WITH MAGNITUDE OF LOW TO MID LEVEL LAPSE RATES (-6.4 C/KM) AND H5 TEMPS (-7.5 C) SLIGHTLY ABOVE NORMAL AND SFC BASED CAPE AROUND 4500 J/KG. STORM MOTION VECTOR FOR THE DAY IS FROM THE EAST AT LESS THAN 3 KNOTS. BASICALLY STORMS WILL BE NEARLY STATIONARY WITH DEVELOPMENT AND MOVEMENT LIKELY DOMINATED BY OUTFLOW BOUNDARY INTERACTIONS. LIMITING FACTOR REMAINS UNIMPRESSIVE MID LEVEL LAPSE RATES. ALL IN ALL, THERMODYNAMIC PROFILE FOR THE DAY INDICATE POTENTIAL FOR WIND GUSTS IN EXCESS OF 40 MPH, FREQUENT LIGHTNING STRIKES, AND LOCALLY HEAVY RAINFALL PARTICULARLY WITH INLAND STORMS. SO WILL AMEND HWO ACCORDINGLY. ENSEMBLE OF HIGH RES MODELS AND HRRR ALSO INDICATE THAT BEST CHANCES OF THUNDERSTORMS TODAY REMAIN FOR THE INTERIOR SOUTH WITH HIGH CHANCES SPREADING TOWARDS THE WEST COAST AND LOWER CHANCES SPREADING AS FAR EAST AS THE WESTERN SUBURBS OF THE EAST COAST METRO AREAS PARTICULARLY STARTING AROUND 2 PM AND INTO THE EARLY EVENING. FORECAST HAS BEEN UPDATED ACCORDINGLY. && .PREV DISCUSSION... /ISSUED 735 AM EDT WED AUG 20 2014/ AVIATION... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE BULK OF THE PERIOD AS HIGH PRESSURE REMAINS IN CONTROL. THE LATEST MODEL RUN SHOWED ISLTD/SCT SHRAS/TSTMS DEVELOPING ALONG THE EAST COAST SEA BREEZE BOUNDARY AROUND 16-17Z JUST INLAND OF THE EAST COAST TAF SITES WITH THE LOW-LEVEL FLOW PROJECTED TO BE MORE ORIENTED OUT OF THE ENE. WILL INCLUDE VCTS FOR THE EAST COAST SITES TO CORRESPOND WITH THIS TIMING FOR NOW AND UPDATE AS CONDITIONS EVOLVE TODAY. THIS ACTIVITY SHOULD CONTINUE INLAND THROUGH THE MID-LATE AFTERNOON AND SETUP ACROSS THE INTERIOR AREAS THROUGH THE EARLY EVENING HOURS BEFORE DIMINISHING TONIGHT. WINDS WILL BECOME CALM AND SHIFT TO OFFSHORE ALONG EACH COAST THROUGH THE LATE NIGHT HOURS. 85/AG PREV DISCUSSION... /ISSUED 238 AM EDT WED AUG 20 2014/ DISCUSSION... SOUTH FLORIDA IS UNDER AN AREA OF HIGH PRESSURE LOCATED OVER THE FLORIDA STRAITS. THE FORECAST CALLS FOR THIS AREA OF HIGH PRESSURE TO MOVE TO THE NORTHWEST INTO THE SOUTHEASTERN US. THE 00Z AUG 20 SOUNDING SHOWS THAT THE SAHARAN DUST THAT HAS BEEN AFFECTING SOUTH FLORIDA SINCE THE WEEKEND IS ERODING BETWEEN 600 AND 700 MB (OR 3-4 KM ABOVE THE SURFACE). THIS IS ALSO DEPICTED BY THE LIDAR LOCATED AT THE UNIVERSITY OF MIAMI. THE LIDAR ALSO SHOWS THAT THE SAHARAN LAYER IS BEING ERODED FROM BELOW. AS THE HIGH PRESSURE CONTINUES TO MOVE TO THE NORTHWEST, AN INFLUX OF ATLANTIC AIR ASSOCIATED WITH A WEAK FRONTAL BOUNDARY OVER THE ATLANTIC (BACK DOOR COLD FRONT) WILL CONTINUE TO PROVIDE A SOURCE OF CLEANER AIR. THE LOW LEVEL VISIBILITY WILL CONTINUE TO IMPROVE AS THE WEEK PROGRESSES. THE CIMMS WATER VAPOR IMAGERY SHOWS INCREASING MOISTURE OVER THE BAHAMAS MOVING OVER SOUTH FLORIDA FOR WEDNESDAY EVENING BEHIND THE DRIER AIR THAT HAS BEEN AFFECTING SOUTH FLORIDA SINCE SATURDAY. THE FORECAST SOUNDINGS ALSO SHOW THIS INCREASE IN PW FOR WEDNESDAY AFTERNOON. THE PW DECREASE AGAIN ON THURSDAY DUE TO THE SUBSIDENCE ASSOCIATED WITH THE HIGH PRESSURE MOVING INTO THE SE US. THE FLOW OF EASTERLY WINDS WILL FAVOR LOWER POPS FOR THE IMMEDIATE EAST COAST WITH THE BEST CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS OVER THE INTERIOR AND WESTERN PORTIONS OF THE COASTAL COUNTIES. THE WEEKEND SEEMS TO BE THE DRIEST PERIOD WITH DRIER AIR FROM THE ATLANTIC AFFECTING SOUTH FLORIDA. CONDITIONS ARE FORECAST TO CHANGE FOR MONDAY AND TUESDAY AS MOISTURE ASSOCIATED WITH THE TROPICAL WAVES OVER THE CENTRAL ATLANTIC IS EXPECTED TO AFFECT SOUTH FLORIDA. AT THE PRESENT TIME IT IS NOT POSSIBLE TO PREDICT IF A TROPICAL SYSTEM COULD AFFECT SOUTH FLORIDA NEXT WEEK, BUT AT LEAST WE CAN BE SOMEWHAT CONFIDENT THAT AN INCREASE IN MOISTURE AND LOW LEVEL FLOW FROM THE SE IS FORECAST FOR THE BEGINNING OF NEXT WEEK ASSOCIATED WITH THESE WAVES. THE CURRENT FORECAST FROM THE NATIONAL HURRICANE CENTER INCLUDES A MEDIUM CHANCE FOR DEVELOPMENT FOR THE NEXT FIVE DAYS. MARINE... WINDS ARE FORECAST TO REMAIN SOUTHEASTERLY TO EASTERLY ACROSS THE ATLANTIC WATERS AROUND OR BELOW 10 KNOTS AND PERSISTING THROUGH WEDNESDAY. AS A RESULT, SEAS ARE FORECAST TO BE 2 FEET OR LESS THROUGH THIS TIME FRAME. SURFACE WINDS ARE THEN FORECAST TO INCREASE SLIGHTLY FOR THE LATTER HALF OF THE WEEK WHILE REMAINING GENERALLY EASTERLY AS HIGH PRESSURE BUILDS NORTH OF THE REGION. PREV DISCUSSION... /ISSUED 126 AM EDT WED AUG 20 2014/ AVIATION... WINDS WILL REMAIN EASTERLY FOR THE EAST COAST TERMINALS WHICH WILL FAVOR THE BEST CHANCE FOR THUNDERSTORMS IN THE INTERIOR. AT THE PRESENT TIME WE ARE NOT INCLUDING VCTS FOR THE EAST COAST TERMINALS SINCE THE CONVECTION IS FORECAST TO DEVELOP WEST OF THE EAST COAST TERMINALS. HOWEVER, INCLUDED VCSH FOR ALL TERMINALS AFTER 15Z EXCEPT PBI. APF HAS THE GREATEST CHANCE OF PRECIPITATION, AS THE EASTERLY FLOW FAVORS THUNDERSTORM DEVELOPMENT OVER THE INTERIOR, AND SOMETIMES IT COULD AFFECT THE NAPLES AREA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 92 78 91 78 / 30 10 30 10 FORT LAUDERDALE 92 81 91 80 / 20 10 30 10 MIAMI 91 80 91 80 / 30 10 30 10 NAPLES 91 78 92 78 / 50 10 50 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ SHORT TERM...52/PS LONG TERM....52/PS
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1013 PM EDT THU AUG 21 2014 .SYNOPSIS... A STRONG UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER MISSISSIPPI VALLEY/GULF COAST CONTINUE TO DOMINATE THE WEATHER ACROSS THE MIDLANDS AND CSRA. THIS WILL CONTINUE INTO FRIDAY. 88D REGIONAL RADAR COMPOSITE SHOWS DECAYING LINE OF SHOWERS MOVING SOUTHEAST ACROSS CENTRAL/EAST NC. THIS WAS ONCE A PART OF A LARGER LINE OF SHOWERS AND THUNDERSTORMS THAT BOTH THE HRRR AND WRF INDICATED WOULD WEAKEN THROUGH THE EVENING HOURS. SATELLITE LOOP SHOWS SOME DEBRIS CLOUDS FROM THIS CONVECTION THAT WILL BE SPREADING ACROSS THE REGION OVERNIGHT...ESPECIALLY ALONG THE NC/SC BORDER. OTHERWISE...SKIES WILL REMAIN MOSTLY CLEAR AND TEMPERATURES FALLING INTO THE LOWER/MIDDLE 70S BY SUNRISE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS. MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO SLIGHT CHANCE DIURNAL TSTMS AT BEST DUE TO BUILDING RIDGE ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF FREE CONVECTION/HIGH CONVECTIVE TEMPS. MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /MONDAY THROUGH THURSDAY/... FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD. SATELLITE LOOP SHOWS CONVECTIVE DEBRIS CLOUDS WILL CONTINUE TO CROSS THE AREA OVERNIGHT...WHICH WILL AGAIN WORK TO PREVENT FOG DEVELOPMENT. GFS LAMP STILL INDICATING MVFR FOG AT AGS/OGB 06Z-13Z. GIVEN EXPECTED DRY AIRMASS AND HIGH CLOUDS...WILL NOT INCLUDE IN FOG IN THE FORECAST. EXPECT LIGHT AND VARIABLE/CALM WINDS OVERNIGHT. ON FRIDAY...WINDS WILL BE FROM THE NORTHWEST/WEST AROUND 5 KTS THROUGH THE DAY. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CDT WED AUG 20 2014 .DISCUSSION... 320 AM CDT SHORT TERM...THROUGH WEDNESDAY NIGHT... FOR THE REMAINDER OF THE OVERNIGHT HOURS...CONDITIONS WILL REMAIN QUIET WITH HIGH PRESSURE OVERHEAD AND THE PESKY UPPER LOW LIFTING INTO THE UPPER GREAT LAKES AND ANY ASSOCIATED CONVECTION MOVING WELL TO THE EAST. UNDER CLEAR SKIES AND LIGHT WINDS...EXPECT THAT SOME LOCATIONS COULD SEE SOME FOG DEVELOPMENT...MAINLY LOW LYING AND SHELTERED AREAS. DO NOT EXPECT WIDESPREAD DENSE FOG AS DEWPOINT DEPRESSIONS ARE STILL 3-5 DEGREES IN MANY PLACES. CONDITIONS WILL REMAIN QUIET INTO WEDNESDAY BUT UPPER RIDGING BUILDING OVER THE CENTRAL PLAINS AND ACROSS THE MIDDLE AND UPPER MISSISSIPPI VALLEY WHILE THE UPPER LOW CONTINUES TO LIFT TO THE NORTHEAST IS SIGNALING THE BEGINNING OF A SIGNIFICANT WARMING TREND...MORE LIKE THE TRUE DOG DAYS OF SUMMER THAT THE UNSEASONABLY COOL WEATHER THAT THE AREA HAS SEE FOR MUCH OF THIS SUMMER. ACCOMPANYING THE UPPER RIDGING AND INCREASING TEMPERATURES ALOFT WILL BE AN INCREASE OF LOW LEVEL MOISTURE. THE BERMUDA HIGH IS IN PLACE OVER THE ERN GLFMEX WHILE A TROUGH OF LOW PRESSURE IS DEVELOPING OVER THE CENTRAL PLAINS. THIS IS SETTING UP A RETURN FLOW OF MOISTURE FROM A WIDE OPEN GULF OF MEXICO...WITH 20-30KT 850MB WINDS WITH TRAJECTORIES OFF OF THE WESTERN GLFMEX POINTING RIGHT INTO THE MIDWEST. UNDER AMPLE SUNSHINE FOR MOST OF THE DAY TODAY...THERE SHOULD BE LITTLE TROUBLE MIXING DOWN THE WARMER AIR ALOFT...WHERE 850MB TEMPS SHOULD BE ARND 18-20C. SO...THE AREA WILL SEE HIGHS TODAY IN THE MIDDLE TO UPPER 80S. WITH DEWPOINTS IN THE MIDDLE TO UPPER 60S...THE MAX HEAT INDEX TODAY SHOULD BE IN THE UPPER 80S TO LOWER 90S. WHILE THESE HEAT INDEX VALUES ARE NOT ANYWHERE NEAR HEADLINE LEVELS...THEY ARE CERTAINLY MUCH HIGHER THAN HAS BEEN SEEN FOR THE BULK OF THE SUMMER. SHOWERS AND THUNDERSTORMS WILL BECOME AN INCREASING CONCERN THROUGH THE AFTERNOON AND INTO WEDNESDAY NIGHT. EARLY THIS MORNING...THERE IS ONGOING CONVECTION OVER THE UPPER MISSOURI VALLEY ASSOCIATED WITH A SHORTWAVE OVER TOPPING THE UPPER RIDGE. EXPECT THAT THIS ACTIVITY SHOULD SLIDE SOUTHEAST OF THE CWA THIS MORNING...MOVING THROUGH SRN IA/NRN MO AND INTO CNTRL/SRN IL. THE MODELS ARE CONSISTENT IN DEVELOPING A WARM FRONT EXTENDING EAST FROM A DEEPENING LOW OVER THE DAKOTAS THROUGH THE MIDDLE MISSISSIPPI VALLEY BY EARLY WEDNESDAY EVENING. THIS SHOULD BE THE FOCUS FOR SHRA/TSRA SPREADING INTO THE REGION FROM SOUTHWEST TO NORTHEAST THROUGH THE EVENING AND OVERNIGHT HOURS WEDNESDAY NIGHT. HAVE MAINTAINED A MORE BROADBRUSHED APPEARANCE TO THE WX/POP/QPF GRIDS FOR WEDNESDAY NIGHT DUE TO SOME CONCERN WITH TIMING OF THE PCPN SPREADING NWD AS THERE IS STILL SOME UNCERTAINTY IN THE MODELS AS FAR AS TIMING THE LEADING EDGE OF THE PCPN...BUT HAVE GONE WITH LIKELY POPS AS CONFIDENCE IS HIGHER IN THE POTENTIAL FOR PCPN. CONFIDENCE IS JUST A LITTLE LOWER IN THE ONSET TIME. WHILE THE SEVERE POTENTIAL WILL BE LOW...A GREATER CONCERN WILL BE LOCALLY HEAVY RAINFALL. AS SWLY FLOW AND WARM/MOIST ADVECTION INCREASES THROUGH WEDNESDAY NIGHT...THE MODEL GUIDANCE IS INDICATING PWATS AROUND 2 INCHES OVER THE AREA. WITH UPPER LEVEL WINDS FROM JUST ABOVE THE SURFACE THROUGH THE COLUMN EXPECTED TO BE ARND 25-30KT...THE THUNDERSTORM ACTIVITY SHOULD BE PROGRESSIVE. SO...WHILE LOCALLY HEAVY RAINFALL IS QUITE POSSIBLE...WIDESPREAD FLOODING IS NOT ANTICIPATED THOUGH LOCALIZED URBAN AND SMALL STREAM ADVISORY TYPE FLOODING REMAINS A POSSIBILITY. KREIN THURSDAY THROUGH SUNDAY... MAIN CONCERN IN THE MEDIUM TERM WILL RESIDE ON THE PLACEMENT/STRENGTH OF THE 500MB RIDGE POISED TO SETUP ACROSS THE OZARKS. GUIDANCE HAS BEEN CONSISTENTLY SUGGESTING AN ATMOSPHERIC RIVER DEVELOPING ACROSS THE NORTHERN PLAINS AND BECOMING ORIENTED ALONG THE NORTHERN PERIPHERY OF THE MID-LVL RIDGE...THEN TURNING SOUTHEAST ACROSS THE ALLEGHENIES IN PENNSYLVANIA. CONCERN DOES ARISE WITH THE FACT THAT MEDIUM RANGE GUIDANCE HAS DEMONSTRATED A REDUCED LEVEL OF CONFIDENCE WITH SPREAD IN HOW AMPLIFIED THE RIDGE WILL BECOME...WHICH COULD BE STARTING TO HINT THAT THE ACTIVE RING-O-FIRE MAY END UP CLOSER TO THE FORECAST AREA THUR NGT/FRI. AT THIS TIME HAVE ONLY MADE MINOR ADJUSTMENTS WITH THE POPS...AND EXPECT A CHANNEL OF LIKELY POPS TO BE LIFTING NORTH THUR MIDDAY INTO WISC BY THUR NGT. CURRENT OPER SOLUTIONS STILL FAVOR THIS SCENARIO...PLUS 850MB TEMPS WILL BE STEADILY WARMING AND SHUD LIMIT THE COVERAGE OF CONVECTION/PRECIP. THEN INTO FRI SOLUTIONS SUGGEST THE TOP OF THE RIDGE MAY BEGIN TO FLATTEN. LOCAL ARW8KM ALSO HINTS THAT THE ACTIVE ZONE MAY BE DRIFTING SOUTH AND COULD BE OVER THE FORECAST AREA FRI AFTN/EVE. THEN FOR SAT RIDGE REMAINS OVERHEAD...BUT IT STILL LOOKS POSSIBLE FOR CHC POPS TO START THE WEEKEND. THE ONE CONSISTENCY THROUGH THE THUR-SAT TIMEFRAME...THE HEAT/HUMIDITY. WHILE PWAT VALUES CONTINUE TO HOVER IN THE 1.6-1.8" RANGE...THE FORECAST DEW PTS ARE EXPECTED TO LINGER IN THE LOW TO PERHAPS MID 70S FOR MANY LOCATIONS THUR-SAT. SFC TEMPS ARE PROGGED TO PUSH WELL INTO THE 80S...AND PERHAPS WARMER YET DEPENDING ON CLOUD COVER/PRECIP. THE COMBINATION OF ANOMALOUSLY HIGH DEW PTS AND SFC TEMPS IN THE UPR 80S/NEAR 90 WOULD SIGNAL HEAT INDEX VALUES IN THE MID/UPR 90S TO PERHAPS THE LOW 100S SOUTH OF I-80...MAINLY FRI-SUN. EARLY NEXT WEEK... ENSEMBLES AND OPER SOLUTIONS CONTINUE TO POINT TOWARDS THE HOT/HUMID AIRMASS BREAKING DOWN AND TRANSITIONING BACK TO A MID CONUS/GREAT LAKES TROUGH. MON WILL LIKELY STILL BE A HOT/HUMID DAY. GUIDANCE HAS DEMONSTRATED SOME CONFIDENCE/CONSISTENCY IN A FRONTAL BOUNDARY APPROACHING THE REGION MON NGT/TUE...WITH MUCH COOLER AIR BEGINNING TO DRIVE SOUTH ACROSS THE NORTHERN PLAINS TUE...AND ARRIVING ACROSS THE CWFA TOWARDS THE MIDDLE OF NEXT WEEK. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * POSSIBLE LAKE BREEZE LATE WEDNESDAY AFTERNOON/EARLY EVENING. KREIN //DISCUSSION...UPDATED 09Z... HAVE REMOVED MENTION OF MVFR VIS IN THE 09Z UPDATE. CONDITIONS SHOULD REMAIN VFR AT THE TERMINALS OVERNIGHT. WESTERLY WINDS INCREASE BY MID TO LATE MORNING WEDNESDAY WITH MODEL FORECAST SOUNDINGS SUGGESTING PREVAILING WINDS AROUND 10 KT...ESPECIALLY DURG THE LATE MORNING HOURS. WINDS ARE EXPECTED TO WEAKEN DURG BY THE LATE AFTERNOON HOURS AS A WEAK RIDGE AXIS DEVELOPS FROM WISCONSIN...THROUGH NERN IL/NWRN IN INTO THE LOWER OHIO VALLEY. A LAKE BREEZE IS EXPECTED TO DEVELOP NEAR THE LAKE AND EVENTUALLY MOVE INLAND...BUT LIKELY NOT REACHING ORD/MDW UNTIL LATE AFTERNOON OR EARLY EVENING. WINDS AT ORD/MDW SHOULD TURN ESELY WITH THE PASSAGE OF THE LAKE BREEZE...BUT THERE WILL ONLY BE A WEAK PUSH TO THE LAKE BREEZE AND THE SSELY WINDS SHOULD ONLY BE ARND 5KT OR SO AT ORD/MDW. WINDS WILL THE SETTLE INTO A SSELY TO SLY DIRECTION THROUGH THE LATE EVENING HOURS. ANOTHER MID LEVEL IMPULSE IS EXPECTED TO DROP OUT OF THE UPPER MISSISSIPPI VALLEY LATE WEDNESDAY NIGHT...BRINGING A CHANCE FOR MORE SHOWERS AND THUNDERSTORMS TO THE REGION. KREIN //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN WIND TRENDS THROUGH THE PERIOD...BUT A LITTLE LOWER CONFIDENCE IN THE EXACT TIMING OF LAKE BREEZE PASSAGE. * LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA WEDNESDAY NIGHT. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY THROUGH SATURDAY...CHANCE OF TSRA. * SUNDAY...SLIGHT CHANCE OF TSRA. * MONDAY...DRY/VFR. && .MARINE... 314 AM CDT SFC LOW PRESSURE CONTINUES TO MEANDER AROUND NORTHERN LOWER MICHIGAN THIS MORNING...ALTHOUGH HAS BEEN WEAKENING. THIS LOW IS EXPECTED TO DRIFT SOUTHEAST AND REACH THE EASTERN GREAT LAKES EARLY THURSDAY. OVER THE NEXT SEVERAL DAYS THE GRADIENT IS EXPECTED TO BE VERY WEAK...SO MOST OF THE WINDS WILL BE LESS THAN 15KT. THIS WILL ALSO RESULT IN WAVES REMAINING LOW...OR GENERALLY LESS THAN 3 FT IN MOST AREAS. WITH THUNDERSTORMS CHANCES OVER THE NEXT SEVERAL DAYS...WINDS/WAVES WILL LIKELY BE ELEVATED IN AND AROUND STORMS. OTHERWISE A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL MOVE FROM THE CENTRAL PLAINS NORTHEAST TO THE UPPER MIDWEST INTO WESTERN ONTARIO. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ 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 NATIONAL WEATHER SERVICE LINCOLN IL 333 AM CDT Wed Aug 20 2014 .SHORT TERM...(Today and tonight) ISSUED AT 333 AM CDT WED AUG 20 2014 Storms have developed along a boundary in northeast MO and southeast IA early this morning. These storms should move into western and southwest IL in the next several hours. These could get into western parts of the CWA so will have some chance pops in the west this morning. However, all models seem to indicate this area will not travel very far and should dissipate during the morning hours. The associated boundary will then slowly lift northeast as a warm front through the CWA, and though convergence along this boundary will be weak, some isolated showers or thunderstorms will remain possible in the early afternoon. By late afternoon and into the evening and overnight hours, the warm front will remain across the central part of the CWA so the chance of showers and thunderstorms will continue during the evening and overnight hours. Temperatures will be a few degrees warmer than yesterday, with some areas in the west and south getting to around 90. Overnight lows will also be warmer as most of the CWA will be in the warm sector overnight. && .LONG TERM...(Thursday through Tuesday) ISSUED AT 333 AM CDT WED AUG 20 2014 Position of the boundary after lifting through the FA today and tonight will have a signif impact on the location of the showers and thunderstorms. Though most recent models are lifting the boundary further to the northeast, some chance pops Thurs and slight chance pops remain in place at least over the northeastern portions of the CWA from Thursday night through Friday night. Pops increasing somewhat for Saturday as models are collapsing the ridge somewhat as a wave moves over the ridge and into the Ohio River Valley. Though the precip chances are scattered at best and low confidence...the models have been very persistent with the very hot temperatures for some summer like conditions that are well above normal for this time of year. Models have also shown consistency with 850 mb temps in the 19-25C range through Sunday. This will drive the temps into the upper 80s/lower 90s with heat indices in the upper 90s/low 100s. Forecast dwpts into the low to mid 70s may be over representing llvl RH enhancement from widespread precip in the models that may not quite come to fruition as widespread. Todays heat indices are more borderline for Heat Advisory criteria...but far more likely to see from Thursday into Sunday with subsequent forecasts, should the trend continue. Into the extended, day 7/just into day 8, models actually beginning to diverge into a solution to break down the ridge with an upper system pushing a return of precip in for Tues night into Wed. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 1145 PM CDT TUE AUG 19 2014 Skies clear across the TAF sites late this evening, but will see some increase in clouds from the west late. Main concern is with potential for fog. Latest short-range guidance suggesting the KSPI-KCMI corridor most at risk for significant fog, as a weak frontal boundary is draped in that area and dew points are pooling along it. However, the increase in clouds near KSPI may help mitigate the fog from getting out of control. The RAP model is fairly robust with widespread dense fog affecting all the TAF sites, but the HRRR has it more patchy within the KPIA/KSPI/KBMI triangle. Right now, will go with a TEMPO period of 1SM at the southern TAF sites and keep it a little higher further north, where the air is a bit drier. Will also need to watch for convection developing along the front in northern Missouri over the next few hours. General thought is that this should stay southwest of KSPI and will not mention at this time. In the longer range of the TAF, concern is with timing of convection late Wednesday afternoon and evening. NAM is faster and much further south with storms moving through as early as 19-21Z, while the latest GFS favors the evening hours, with other guidance much more widely scattered but in the evening. Will favor the later time frames with VCTS mention in the TAFs, although confidence is somewhat uncertain at this time. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AUTEN LONG TERM...HJS AVIATION...GEELHART
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
104 AM CDT WED AUG 20 2014 .DISCUSSION... 835 PM CDT FOR EVENING UPDATE... HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT CHANGES MADE TO GOING FORECAST. A FEW ISOLATED SHOWERS CONTINUE TO BUBBLE IN A COUPLE OF SPOTS AT 0115Z...ONE NEAR KANKAKEE...AND THE OTHER ACROSS NORTHERN COOK COUNTY NEAR OHARE AND JUST OFF THE LAKE SHORE BETWEEN KENILWORTH AND EVANSTON. THESE SHOWERS WERE OCCURRING ALONG A WEAK SURFACE TROUGH AXIS WHICH STRETCHED FROM SOUTHERN LAKE MICHIGAN TO NORTH OF ST LOUIS...AND AHEAD OF A MID-LEVEL SHORT WAVE TROUGH ROTATING EASTWARD ACROSS NORTHWEST IL/WISCONSIN PER GOES VAPOR IMAGERY. THESE SHOWERS HAVE DIMINISHED CONSIDERABLY IN COVERAGE WITH SUNSET AND THE WEAKENING OF DIURNALLY-DRIVEN INSTABILITY...AND LINGERING SHOWERS ARE EXPECTED TO CONTINUE TO WEAKEN AND DISSIPATE OR MOVE OVER LAKE MICHIGAN IN THE NEXT HOUR OR TWO. STRONGER STORMS WHICH HAD FORMED OVER PARTS OF EAST CENTRAL IL AND NORTHWEST INDIANA LATE THIS AFTERNOON ALSO OCCURRED AHEAD OF A MORE COMPACT VORT MAXIMA SEEN PUSHING EAST ACROSS CENTRAL IL AT THIS TIME... AND WITHIN A MORE UNSTABLE ENVIRONMENT ASSOCIATED WITH POOLED UPPER 60S AND LOWER 70S SURFACE DEW POINTS AHEAD OF THE SURFACE TROUGH. THESE STRONGER STORMS HAVE MOVED OFF TO THE EAST OF THE CWA INTO CENTRAL AND NORTHERN INDIANA. GOES 11-3.9 MICRON IR IMAGERY INDICATES LITTLE LEFT OF DIURNAL CU FIELD ACROSS SOUTHERN WI/NORTHERN IL WEST OF CHICAGO...SUGGESTING DRY CONDITIONS FOR THE MAJORITY OF THE AREA FOR THE REMAINDER OF THE EVENING/OVERNIGHT HOURS. ANOTHER MID-LEVEL VORT ROTATING SOUTH-SOUTHEASTWARD ACROSS CENTRAL MN HAS SOME ISOLATED CONVECTION NEAR THE MSP AREA...AND HIGH-RES GUIDANCE DOES INDICATE THE POTENTIAL FOR A FEW ISOLATED SHOWERS TO DEVELOP INTO NORTHEAST IA/NORTHWEST IL TOWARD MORNING. STILL...APPEARS FAIRLY LOW CHANCE WITH BETTER PRECIP POTENTIAL BECOMING FOCUSED BACK ACROSS NEBRASKA/WESTERN IA BY MORNING. HAD ADJUSTED POPS/WX AND SKY COVER EARLIER BASED ON RADAR/SATELLITE TRENDS. OTHER THAN DETAILS OF ENDING/MOVING ISOLATED SHRA OUT OF NORTHEAST IL/NORTHWEST IN NEXT COUPLE OF HOURS...NO SIGNIFICANT CHANGES MADE TO GOING FORECAST. RATZER //PREV DISCUSSION... 304 PM CDT WARMER AND MORE HUMID CONDITIONS ARE STILL EXPECTED AS WE GO THROUGH THE REST OF THE WEEK WITH THE BIGGEST CHALLENGE BEING THE DETERMINATION OF THE EXTENT OF SHOWER AND THUNDERSTORM ACTIVITY. AFTERNOON WATER VAPOR IMAGERY SHOWS AN UPPER TROUGH OVERHEAD OF THE LOCAL AREA MAKING GRADUAL PROGRESS TO THE EAST. BROAD LOW-AMPLITUDE RIDGING IS IN PLACE OVER THE ROCKIES AND HIGH PLAINS WHILE A BROAD UPPER TROUGH MOVES ACROSS WESTERN CANADA. A CUTOFF UPPER LOW IS SPINNING SOUTHWARD DOWN THE CALIFORNIA COAST. THIS RIDGE/TROUGH COMBINATION WILL AMPLIFY OVER THE NEXT FEW DAYS AND MAKE EASTWARD PROGRESS. AT THE SURFACE...LOW PRESSURE IS OVER NORTHERN MICHIGAN IS DRAGGING A COOL FRONTAL BOUNDARY/TROUGH SOUTHEAST ACROSS THE LOCAL AREA. TONIGHT AND WEDNESDAY...THE UPPER TROUGH OVER THE AREA TODAY WILL BE SLOW TO MOVE EAST INTO WEDNESDAY KEEPING CYCLONIC FLOW OVERHEAD THROUGH THE MORNING. THE BULK OF THE CONVECTIVE ACTIVITY IS NOW OFF TO THE EAST WITH MORE SPOTTY DIURNALLY DRIVEN ACTIVITY WORKING INTO THE NORTHERN CWA AND MAY SEE SOME ADDITIONAL ACTIVITY INTO CENTRAL AREAS BEFORE DISSIPATING THIS EVENING. OTHERWISE...WATER VAPOR SHOWS A WEAK WAVE ROUNDING THE PERIPHERY OF THE UPPER LOW OVER MINNESOTA THIS AFTERNOON AND THIS SHOULD ROTATE OVER THE LOCAL AREA TONIGHT AND MAY TRIGGER SOME ADDITIONAL SHOWERS. THE CHANCE DOES NOT LOOK THAT GREAT ESPECIALLY WITH A MODESTLY DRIER AIRMASS IN PLACE BEHIND THE AFTERNOON TROUGH. CYCLONIC FLOW REMAINS OVERHEAD WEDNESDAY MORNING BUT SHIFTS TO THE EAST SO AM NOT EXPECTING PRECIP ACTIVITY GIVEN THE POOR DIURNAL SUPPORT THEREFORE MUCH OF THE DAY WEDNESDAY SHOULD BE DRY. HIGHS WILL WARM INTO THE LOW TO MID 80S BUT A LAKE BREEZE SHOULD COOL LAKESHORE AREAS DURING THE AFTERNOON. WEDNESDAY NIGHT THROUGH FRIDAY...THE UPPER RIDGE WILL MOVE FROM THE HIGH PLAINS AND SLOW ITS EASTWARD PROGRESS OVER THE LOCAL AREA BY FRIDAY. IT WILL AMPLIFY AS IT MOVES EASTWARD HELPING TO SHARPEN THE ASSOCIATED MID LEVEL BAROCLINIC ZONE WHICH WILL MOVE NORTHEAST ACROSS THE FORECAST AREA STARTING BY WEDNESDAY EVENING. WITH A STRONG PUSH OF MOISTURE AND A WEST TO SOUTHWEST LOW LEVEL JET DEVELOPING WEDNESDAY EVENING SHOULD SEE A DECENT COVERAGE OF SHOWERS AND THUNDERSTORMS DEVELOP AND MOVE ACROSS THE AREA INTO THURSDAY MORNING. BETTER ORGANIZATION COULD RESULT WITH THE PASSAGE OF ANY SHORTWAVE EJECTING FROM THE AMPLIFYING BUT STILL BROAD WESTERN TROUGH. LESS CONFIDENT IN PRECIP CHANCES FROM LATE THURSDAY THROUGH FRIDAY AS THE RIDGE AXIS WILL BE OVER THE AREA BUT THE RIDGE LOOKS TO BE BROAD ENOUGH THAT THE MORE ACTIVE FLOW AROUND THE PERIPHERY WILL BE IN CLOSE PROXIMITY. ULTIMATELY A WARM FRONTAL BOUNDARY WILL LIKELY SET UP TO THE NORTH EXTENDING FROM LOW PRESSURE ACROSS THE CENTRAL/NORTHERN PLAINS BUT CONVECTION MAY INFLUENCE HOW FAR NORTH-SOUTH THIS BOUNDARY MOVES WHICH WILL AFFECT POPS AND POSSIBLY TEMPS AS WELL. WILL CONTINUE WITH THE IDEA OF THE BOUNDARY REMAINING NORTH LEADING TO HIGHS IN THE MID AND UPPER 80S THURSDAY AND UPPER 80S TO AROUND 90 FRIDAY. THE FLOW MAY BE WEAK ENOUGH TO ALLOW SOME LAKE INFLUENCE TO COOL SHORELINE AREAS SOMEWHAT. ANY OUTFLOW FROM STORMS OVER OR NORTH OF THE AREA COULD IMPACT TEMPS AS WELL. SATURDAY AND BEYOND...THE WESTERN TROUGH WILL EVENTUALLY TRACK EAST ACROSS THE NORTHERN PLAINS BREAKING DOWN THE RIDGE BUT THE SPEED WITH WHICH THIS OCCURS IS STILL IN QUESTION. AT THIS POINT THE RIDGE LOOKS TO FURTHER AMPLIFY OVER THE WEEKEND WHICH COULD KEEP THINGS DRY BUT GUIDANCE HAS FLUCTUATED ON THE AMPLITUDE. WILL KEEP LOW POPS SATURDAY AND SUNDAY...MAINLY NORTH CLOSER TO THE MORE ACTIVE FLOW AROUND THE TOP OF THE RIDGE. TEMPS IN THE UPPER 80S TO AROUND 90 WILL CONTINUE ALONG WITH THE HUMIDITY. AS THE UPPER TROUGH MOVES EAST SURFACE LOW PRESSURE WILL LIKELY DEVELOP ACROSS THE NORTHERN PLAINS AND DRAG A COLD FRONT INTO THE AREA EARLY NEXT WEEK. THE OVERALL UPPER PATTERN WILL BE DE-AMPLIFYING SO THE FRONT MAY STALL OUT SOMEWHERE NEAR THE AREA BUT STILL QUITE A WAYS OUT THERE FOR ANY KIND OF CONFIDENCE IN THIS. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * CHANCE MVFR VIS OVERNIGHT INTO EARLY WEDNESDAY MORNING. * POSSIBLE LAKE BREEZE LATE WEDNESDAY AFTERNOON/EARLY EVENING. KREIN //DISCUSSION...UPDATED 06Z... ALL CONVECTIVE ACTIVITY HAS MOVED OUT OF NRN IL/NWRN IN AND SKIES HAVE BECOME MOSTLY CLEAR WITH CALM TO LIGHT WEST WINDS. CLEAR SKIES LIGHT WINDS AND DEWPOINTS IN THE 60S SHOULD ALLOW FOR SOME FG/BR DEVELOPMENT AS TEMPERATURES RADIATE DOWN CLOSE TO THE IN SITU DEWPOINTS. WILL CARRY MVFR VIS AT ALL TERMINAL EXCEPT ORD/MDW WHERE URBAN HEAT ISLAND EFFECTS COULD KEEP TEMPS A LITTLE HIGHER...AND SATURATION WOULD BE LESS LIKELY. A FEW ISOLD POCKETS OF IFR VIA ARE POSSIBLE IN LOW LYING...SHELTERED LOCATIONS. WESTERLY WINDS INCREASE BY MID TO LATE MORNING WEDNESDAY WITH MODEL FORECAST SOUNDINGS SUGGESTING PREVAILING WINDS AROUND 10 KT...ESPECIALLY DURG THE LATE MORNING HOURS. WINDS ARE EXPECTED TO WEAKEN DURG BY THE LATE AFTERNOON HOURS AS A WEAK RIDGE AXIS DEVELOPS FROM WISCONSIN...THROUGH NERN IL/NWRN IN INTO THE LOWER OHIO VALLEY. A LAKE BREEZE IS EXPECTED TO DEVELOP NEAR THE LAKE AND EVENTUALLY MOVE INLAND...BUT LIKELY NOT REACHING ORD/MDW UNTIL LATE AFTERNOON OR EARLY EVENING. WINDS AT ORD/MDW SHOULD TURN ESELY WITH THE PASSAGE OF THE LAKE BREEZE...BUT THERE WILL ONLY BE A WEAK PUSH TO THE LAKE BREEZE AND THE SSELY WINDS SHOULD ONLY BE ARND 5KT OR SO AT ORD/MDW. WINDS WILL THE SETTLE INTO A SSELY TO SLY DIRECTION THROUGH THE LATE EVENING HOURS. ANOTHER MID LEVEL IMPULSE IS EXPECTED TO DROP OUT OF THE UPPER MISSISSIPPI VALLEY LATE WEDNESDAY NIGHT...BRINGING A CHANCE FOR MORE SHOWERS AND THUNDERSTORMS TO THE REGION. KREIN //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN WIND TRENDS THROUGH THE PERIOD...BUT A LITTLE LOWER CONFIDENCE IN THE EXACT TIMING OF LAKE BREEZE PASSAGE. * MEDIUM TO HIGH CONFIDENCE THAT VIS WILL DROP TO MVFR WITH ISOLD IFR ACROSS THE REGION...AND MEDIUM CONFIDENCE THAT VIS AT ORD/MDW WILL REMAIN 6SM OR HIGHER. * LOW CONFIDENCE IN TIMING AND COVERAGE OF SHRA/TSRA WEDNESDAY NIGHT. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY THROUGH SATURDAY...CHANCE OF TSRA. * SUNDAY...SLIGHT CHANCE OF TSRA. * MONDAY...DRY/VFR. && .MARINE... 319 PM CDT GENERALLY QUIET CONDITIONS OVER THE LAKE THROUGH THE WEEKEND WITH RESPECT TO WINDS AND WAVES...AND PERIODS WHERE DIRECTIONS IN THE NEARSHORE AREAS WILL BE CONTROLLED BY LAKE BREEZE INFLUENCES BY DAY. A WARM AND MOIST AIR MASS WILL OVERSPREAD THE REGION AND UPPER LEVEL DISTURBANCES COULD RESULT IN THUNDERSTORM COMPLEXES CROSSING THE LAKE AT TIMES...MAINLY FROM WEDNESDAY NIGHT THROUGH SATURDAY. THE POTENTIAL EXISTS FOR SOME OF THESE COMPLEXES TO PRODUCE GUSTY WINDS AND LOCALLY HIGHER WAVES...AS WELL AS FREQUENT CLOUD TO WATER LIGHTNING. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ 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 NATIONAL WEATHER SERVICE LINCOLN IL 1200 AM CDT Wed Aug 20 2014 .UPDATE... ISSUED AT 830 PM CDT TUE AUG 19 2014 Weak frontal boundary currently extending from northeast Illinois through the Galesburg area to far northern Missouri. Earlier convection has pushed well to the east and skies are now mostly clear in our area, although some rogue thunderstorms have recently developed along an outflow boundary across Clark County. Not any appreciable change in temperature on either side of the front, but dew points are slightly lower to the north. Front is not expected to make much additional headway overnight. HRRR and RAP showing some additional convection developing overnight on the tail of the front across northern Missouri southeast to near St Louis. Currently think the precip should stay to our southwest, but will see an increase in clouds after midnight across the southwest CWA. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 256 PM CDT TUE AUG 19 2014 19z/2pm surface analysis shows slow-moving cold front along the Mississippi River. Isolated showers and thunderstorms are beginning to develop immediately along the boundary within a narrow uncapped instability axis. Further east, the air mass across much of central Illinois remains capped in the wake of convection that moved across the area earlier in the day. Will hold on to slight chance PoPs through the early evening as the front makes its way slowly eastward into the KILX CWA. Once daytime instability is lost, will go with a dry forecast across the board overnight. With the boundary in the vicinity, winds will become light/variable tonight, setting up the possibility of fog. Forecast soundings suggest low-level moisture will remain high, with both the MET and MAV guidance indicating reduced visbys. Based on this guidance and a persistence forecast from the past couple of nights, have included patchy fog after midnight. Weak frontal boundary will remain in the area on Wednesday, resulting in a continued slight chance for showers/thunder, with afternoon highs climbing into the middle to upper 80s. && .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 256 PM CDT TUE AUG 19 2014 Wednesday night after midnight had previously looked like our best chances of storms over the next few days, but the 12z guidance has sped up the shortwave/MCV by 6-12 hours and weakened it. Our area will still remain along the storm track over the building upper level ridge, so despite lowering PoPs below the likely category, chances will remain in most areas, with lowest chances southwest of Springfield to Effingham. The theme of higher storm chances in N-NE Illinois will continue for the balance of the extended forecast, as the upper ridge and dome of hot air build from southwest to northeast. The storm track appears to generally follow the 588dm 500mb height line into this weekend. We kept a narrow channel of chance PoPs across our N-NE counties from Thursday to Saturday, with minor shifts east and west during that time. Slight chances could extend as far south as Rushville to Lincoln to Mattoon, but the building dome of heat should provide enough mid-level capping to limit the southward extent of storms. Model differences in the Sunday to Tuesday time frame have prompted a continuation of periodic slight chance PoPs as a cold frontal boundary tries to push into the dome of hot air. The 12z runs have limited the forward progression of the front into IL on Sunday night and Monday, when previous runs indicated an air mass change for less hot conditions on Monday. Now the heat may linger as long as Tuesday with the only hints of relief coming for areas north of I-74. Heat index readings from Wednesday to Sunday will climb to into the 95F to 102F range at peak heating, which could be locally limited by any pop-up thunderstorms each afternoon. Heat advisory levels are 105F+, but conditions will still be very uncomfortable, and heat precautions will be necessary each day. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 1145 PM CDT TUE AUG 19 2014 Skies clear across the TAF sites late this evening, but will see some increase in clouds from the west late. Main concern is with potential for fog. Latest short-range guidance suggesting the KSPI-KCMI corridor most at risk for significant fog, as a weak frontal boundary is draped in that area and dew points are pooling along it. However, the increase in clouds near KSPI may help mitigate the fog from getting out of control. The RAP model is fairly robust with widespread dense fog affecting all the TAF sites, but the HRRR has it more patchy within the KPIA/KSPI/KBMI triangle. Right now, will go with a TEMPO period of 1SM at the southern TAF sites and keep it a little higher further north, where the air is a bit drier. Will also need to watch for convection developing along the front in northern Missouri over the next few hours. General thought is that this should stay southwest of KSPI and will not mention at this time. In the longer range of the TAF, concern is with timing of convection late Wednesday afternoon and evening. NAM is faster and much further south with storms moving through as early as 19-21Z, while the latest GFS favors the evening hours, with other guidance much more widely scattered but in the evening. Will favor the later time frames with VCTS mention in the TAFs, although confidence is somewhat uncertain at this time. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEELHART SHORT TERM...BARNES LONG TERM...SHIMON AVIATION...GEELHART
AREA FORECAST DISCUSSION
NWS DES MOINES IA
339 PM CDT WED AUG 20 2014 .SHORT TERM /TONIGHT/... ISSUED AT 340 PM CDT WED AUG 20 2014 TONIGHTS FORECAST IS QUITE DIFFICULT AND THE MODELS ARE NOT MUCH HELP. A WARM FRONT ACROSS IOWA STRETCHES FROM A LOW OVER WEST CENTRAL SOUTH DAKOTA. THETA-E ADVECTION AND SOME MODEST INSTABILITY KEPT THUNDERSTORMS FESTERING AHEAD OF THE FRONTAL BOUNDARY ALL DAY LONG AND SHEAR ACTUALLY INCREASED THROUGH THE AFTERNOON HOURS. THE MODELS CONTINUE THE SHOWERS/STORMS ALONG AND AHEAD OF THE FRONTAL BOUNDARY IN A ZONE OF WARM ADVECTION THROUGH THE AFTERNOON HOURS INTO EARLY EVENING. THE HRRR AND HOPWRF THEN SQUELCH THE PRECIP IN IOWA OVERNIGHT WHILE THE NAM CONTINUES TO DEVELOP STORMS ACROSS NORTH CENTRAL/NORTHEAST IOWA...ESPECIALLY WITH A LOW LEVEL JET THAT INTENSIFIES LATER THIS EVENING. IT IS VERY HARD TO SAY WHERE THAT BOUNDARY WILL LIFT TO THIS EVENING...OR WILL IT REMAIN FAIRLY STATIONARY. I AM REASONABLY CERTAIN THAT WE WILL NOT BE DRY ACROSS THE NORTH BUT I AM SKEPTICAL ABOUT KEEPING 60-70 POPS IN THAT AREA GIVEN THE TRENDS FOR THE PRECIP TO SLOWLY LIFT NORTH. THE MAIN ADJUSTMENTS TO THE GOING FORECAST WERE TO LOWER POPS SOME ACROSS THE NORTH AND MENTION HEAVY RAIN ACROSS A PART OF THE NORTH CENTRAL AND NORTHEAST. HOWEVER...IF THE NAM12 IS CORRECT MY FORECAST WILL NEED TO BE ADJUSTED ONCE THE LLJ COMES INTO PLAY AFTER 03Z OR SO AS HIGHER POPS WILL BE NEEDED FURTHER SOUTH. HEAVY RAINFALL WILL ALSO BE MORE OF A CONCERN ACROSS AREAS NORTH OF HIGHWAY 20. .LONG TERM /THURSDAY THROUGH WEDNESDAY/... ISSUED AT 340 PM CDT WED AUG 20 2014 RELATIVELY ACTIVE CONDITIONS TO PERSIST FOR MUCH OF THE LONG TERM WITH BROAD WSW FLOW ALOFT AND SURFACE BOUNDARY NEARBY. ANY ONGOING CONVECTION ON THURSDAY MORNING SHOULD DISSIPATE WITH FORCING WEAKENING. WARM SECTOR WILL BE IN PLACE WITH TEMPERATURES CLIMBING NICELY THROUGH THE DAY. STILL MAY SEE SOME MID TO HIGH CLOUDS OVERHEAD AND THIS MAY LIMIT DAYTIME HIGHS...HOWEVER STILL A VERY WARM AND HUMID DAY EXPECTED FOR MOST LOCATIONS. SURFACE BOUNDARY WILL EASE INTO NORTHERN IOWA ON THURSDAY NIGHT WITH SOME SCATTERED CONVECTION EXPECTED ALONG THE FRONT OVERNIGHT. THESE STORMS ARE EXPECTED TO WEAKEN OVERNIGHT TOWARD DAYBREAK AS INFLOW WEAKENS AND COL REGION PUSHES INTO THE STATE. FRIDAY WILL SEE THE COL PASS THROUGH IOWA WITH LIMITED CONVECTION CHANCES FOR MUCH OF THE DAY. HOWEVER...A MORE VIGOROUS SHORTWAVE WILL EJECT INTO THE PLAINS LATER FRIDAY WITH INCREASING FLOW INTO THE FRONT LATE FRIDAY INTO FRIDAY NIGHT. MODELS HAVE ALL BEEN INDICATING RATHER ROBUST CONVECTION BY LATE FRIDAY ACROSS THE PLAINS PUSHING INTO IOWA OVERNIGHT. HAVE CONTINUED THE HIGHER POPS ON FRIDAY NIGHT...ESPECIALLY ACROSS THE NORTHWEST WHERE THE BEST FORCING AND INFLOW INTO SYSTEM IS ANTICIPATED. THE THREAT FOR CONVECTION WILL PERSIST INTO THE WEEKEND AND EARLY NEXT WEEK AS THE FRONTAL BOUNDARY REMAINS NEAR THE STATE. AT THIS POINT...IT APPEARS MUCH OF THE CONVECTION THIS WEEKEND WILL BE NEAR NORTHERN IOWA WITH HOT AND HUMID CONDITIONS IN THE SOUTH. THE BULK OF THE SYSTEM IS NOT EXPECTED TO PASS THROUGH THE REGION UNTIL THE MIDDLE OF NEXT WEEK WHEN GOOD COVERAGE OF STORMS IS ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY. TEMPERATURES WILL REMAIN VERY WARM TO HOT SOUTH OF THE BOUNDARY DURING THIS TIME. THE THREAT FOR HEAVY RAINFALL WILL BE EVER PRESENT WITH THIS CONVECTION FOR MUCH OF THE FORECAST. PWAT VALUES WILL IN GENERAL BE AT OR ABOVE 1.50" WITH CONVECTION EAST OR SOUTHEAST AND TRAINING A POSSIBILITY FROM TIME TO TIME. WHILE WIDESPREAD FLOODING IS NOT EXPECTED GIVEN MATURE VEGETATIVE GROWTH...LOCALIZED FLOODING MAY OCCUR. THE PRIMARY FLASH FLOOD THREAT WILL REMAIN IN URBAN AREAS. HOWEVER...IF SEVERAL NIGHTS OF RAIN DO OCCUR IN THE SAME AREA...A MORE GENERALIZED FLASH FLOOD THREAT MAY MATERIALIZE. THE OTHER CONCERN WILL BE WITH HOT AND HUMID CONDITIONS SOUTH OF THE BOUNDARY. HEAT INDEX VALUES ARE EXPECTED TO CLIMB ABOVE 100 DEGREES FROM TIME TO TIME AND MAY BECOME PROBLEMATIC...ESPECIALLY IN SOUTHERN IOWA SHOULD SEVERAL DAY STRING TOGETHER OF HOT AND STICKY CONDITIONS. MUCH WILL DEPEND ON THE EXTEND OF CONVECTION AND WHERE OUTFLOW BOUNDARYS AND SUBSEQUENT CONVECTION END UP. AT THIS POINT...GIVEN THE UNCERTAINTY...NO HEADLINES FOR HEAT WILL BE ISSUED. && .AVIATION...20/18Z ISSUED AT 1248 PM CDT WED AUG 20 2014 SHOWERS AND THUNDERSTORMS PERSIST IN A ZONE OF INSTABILITY AHEAD OF A WARM FRONT OVER SOUTHERN IOWA THAT EXTENDS BACK INTO SOUTH DAKOTA. SHOWERS AND STORMS KEEP REDEVELOPING IN THIS ZONE EVEN BACK INTO NEBRASKA AND WILL CONTINUE TO FESTER OVER TAF LOCATIONS FROM FOD TO ALO AND MCW THROUGH 02Z. THERE MAY BE A SHORT BREAK THIS EVENING BEFORE A STRONG PUSH OF MOISTURE SURGES INTO IOWA ON A STRONG LOW LEVEL JET. ALONG AND NORTH OF THE FRONTAL BOUNDARY STORMS MAY INTENSIFY PRODUCING HEAVY RAINFALL AND A FEW OF THE MORE ROBUST STORMS MAY PRODUCE STRONG WIND AND HAIL. MVFR VSBYS WILL LARGELY PREVAIL EITHER DUE TO FOG AND/OR HEAVY RAIN. CIGS WILL ALSO LOWER IN THUNDERSTORMS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...FAB LONG TERM...COGIL AVIATION...FAB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1138 PM CDT TUE AUG 19 2014 .SYNOPSIS... ISSUED AT 305 PM CDT TUE AUG 19 2014 WEAK HIGH PRESSURE OVER IOWA WILL MOVE EAST AS A WARM FRONT DEVELOPS TO THE SOUTH AND BEGINS TO LIFT NORTH TONIGHT. THE FRONT WILL LIFT NORTH OF THE STATE ON WEDNESDAY NIGHT. STRONG S/WV WILL MOVE UP THE BACK SIDE OF THE UPPER LEVEL RIDGE AND PUSH A COLD FRONT ACROSS THE STATE THIS WEEKEND. && .SHORT TERM /TONIGHT/... ISSUED AT 305 PM CDT TUE AUG 19 2014 A SURFACE LOW DEVELOPING OVER NORTHEAST COLORADO WILL SHIFT INTO NORTHWEST NEBRASKA OVERNIGHT. AN ASSOCIATED WARM FRONT WILL EXTEND FROM THE LOW THROUGH EASTERN NEBRASKA AND INTO SOUTHWEST IOWA AND NORTHERN MISSOURI BY 12Z WEDNESDAY BEFORE SURGING NORTH THROUGH THE DAY WEDNESDAY. STRONG THETA-E ADVECTION IS FORECAST TO LIFT ACROSS CENTRAL IOWA DURING THE OVERNIGHT HOURS...ESPECIALLY AFTER 06Z. FORCING IS WEAK BUT DOES IMPROVE OVERNIGHT AS A LOW LEVEL JET FOCUSES INTO SOUTHWEST IOWA. ALOFT A WEAK SHORTWAVE IS PROGGED TO MOVE ACROSS EASTERN NEBRASKA/SOUTHWEST IOWA. THIS SHOULD BE ENOUGH TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST INTO CENTRAL IOWA. STORMS SHOULD MAINLY BE ELEVATED AS LOW LEVEL CONVERGENCE IS WEAK TO NON EXISTENT. THERE IS ALSO SOME WEAK SHEAR...PERHAPS ENOUGH FOR AN ISOLATED STORM TO BRIEFLY PRODUCE SOME MARGINALLY SEVERE TO SEVERE HAIL. THE HIGH RES AND NAM12 MODELS ARE NOT AS IMPRESSIVE WITH DEVELOPING STORMS ACROSS THE AREA BUT THE SREF DOES AS DOES PREVIOUS RUN OF THE HI-RES MODELS. THE HRRR IN PARTICULAR IS FAIRLY BULLISH ON BRINING PRECIP INTO THE SW WHILE THE MEMBERS OF THE HOPWRF ARE A LITTLE MORE RESERVED...AT LEAST THROUGH 09Z. SOME POTENTIAL FOR FOG ACROSS THE NORTHEAST OVERNIGHT AS REMAINING CLOUDS ACROSS THE AREA DISSIPATE WITH SUNSET AND SURFACE RIDGING MOVES OVERHEAD PRODUCING LIGHT WIND. NOT LOOKING AT DENSE FOG AT THIS POINT GIVEN THE VERY SHALLOW NATURE OF THE MOISTURE MOVING IN. GENERALLY WENT WITH PATCHY FOG WORDING HOWEVER ALO/MCW WILL BE EAST OF THE RIDGE AXIS AND MOISTURE COULD BE ENOUGH FOR A LITTLE MORE WIDESPREAD FOG SO I MENTION AREAS OF FOG OVER THESE LOCATIONS. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... ISSUED AT 305 PM CDT TUE AUG 19 2014 A BREAK IN THE CONVECTION IS EXPECTED ON WED AS THE FIRST ROUND OF THETA-E ADVECTON LIFTS OUT OF THE STATE. A RENEWED THREAT OF THUNDERSTORMS WILL COME AS THE WARM FRONT LIFTS NORTH AND STRONG THETA-E ADVECTION TAKES PLACE WED NIGHT. THE H8 SHOWS GOOD SPEED CONVERGENCE AND THERE IS DIVERGENCE ALOFT...THE FLY IN THE OINTMENT WILL BE IF THE ATMOSPHERE CAPS OFF OR NOT. AN EML IS IN PLACE...BUT IT IS NOT ALL THAT STRONG. WARM AND HUMID WEATHER WILL HOLD INTO THE WEEKEND WITH AFTERNOON HEAT INDICES IN THE LOW TO MID 90S NORTH...AND 95 TO 105 SOUTH TUE-THU AFTERNOON. BELOW CRITERIA...BUT WILL MENTION IN THE HWO WITH ALL THE SCHOOL ACTIVITIES GOING ON. COOLER WEATHER WILL MOVE IN OVER THE WEEKEND...FIRST DUE TO THE INCREASED CLOUD COVER...THEN DUE TO THE FRONTAL PASSAGE SAT. COOL AIR WILL SETTLE IN SLOWLY WITH TEMPS FALLING BELOW NORMAL; FOR MON AND TUE. && .AVIATION...20/06Z ISSUED AT 1134 PM CDT TUE AUG 19 2014 BOUNDARY WILL LIFT ACROSS IOWA THROUGH WEDNESDAY...THIS WILL BRING CHANCES FOR SHRA/TSRA TO SITES...PRIMARILY SOUTHERN SITES THROUGHOUT THE PERIOD. BEST CHANCES WILL COME BEFORE 12Z...BEFORE DECREASING. HAVE INCLUDED VC MENTION AT KFOD/KDSM/KOTM. NORTHERN SITES WILL LIKELY SEE BR/FG NEAR 12Z GIVEN AMPLE LOW LEVEL MOISTURE. MVFR...IFR OR LOWER CEILINGS AND VISIBILITIES WILL BE POSSIBLE AT TIMES AT SITES THROUGH 12Z BEFORE IMPROVING QUICKLY AFTER 12Z. WINDS WILL BECOME SOUTHERLY AND CONDITIONS WILL REMAIN VFR THROUGH REMAINDER OF PERIOD. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MS AUG 14 SHORT TERM...FAB LONG TERM...MS AUG 14 AVIATION...AWB
AREA FORECAST DISCUSSION
NWS TOPEKA KS
732 PM CDT Thu Aug 21 2014 .UPDATE... Issued at 732 PM CDT THU AUG 21 2014 Will be updating the forecast soon to remove the heat advisory as HI values have fallen below 105 already and temps will continue to cool. Am a little concerned that we may be dealing with convection across northern KS for much of the evening. A 00Z objective surface analysis suggests a weak trough axis or boundary has laid over more west to east into northeast KS and the outflow from convection over north central KS will likely help better define this boundary. Once the low level jet increases this evening, there could be enough lift along this boundary for scattered storms to fester through much of the night. This seems to be the idea anyways from the HRRR and RAP, although they may be a little to far south with the QPF. Not sure how long a downbust threat may last as cooling of the boundary layer should increase convective inhibition. But locally heavy rainfall could be a concern as models show more than enough moisture (PWs around 2 inches) available for moderate and heavy rainfall. With this in mind will have tweaked POPs up a little for at least this evening across north central and northeast KS. && .SHORT TERM...(This Evening through Friday) Issued at 356 PM CDT THU AUG 21 2014 At 3 PM, surface low pressure was situated over the Oklahoma panhandle...connected by a weak cold front to another surface low in southwest Minnesota. There was a second weak boundary, more of a moisture discontinuity extending from just north of Russel, KS to near Marysville, KS. immediately north of this moisture boundary, low-level convergence and the presence of deeper moisture/more instability have led to persistent showers and a few storms in southern Nebraska and extreme northern Kansas. Aloft, a stream of very weak disturbances were moving out of the desert southwest into the central Plains, and will continue to do so through tomorrow. Southwest flow aloft on the west side of an upper ridge has allowed for continuous warm advection and a very hot regime locally. Temperatures today have been in the upper 90s to lower 100s (with the exception of areas very close to the NE border where there have been more clouds) while dewpoints especially north and east have held in the lower 70s. This has led to heat index values in the 102 to 108 range with the highest values east. Have issued a heat advisory for northeast and east central KS where the highest T/Td combinations should be in place through this evening. This evening into tonight, will be watching a few features for potential thunderstorm development. The first is the frontal zone in north central KS. Surface based CAPE greater than 1000 J/kg is in place in the airmass just north of the weak boundary. Wind shear is rather weak, but between the ample afternoon heating of the boundary and what seems to be an incoming weak short wave trough, could see scattered thunderstorm development in north central KS. If storms can develop through early evening, the very steep low level lapse rates would support localized strong downbursts. However, severe potential appears low as there may not be sufficient lift/instability to support the precip loading needed for severe winds. Will need to monitor regardless as the depth of the steep lapse rates would support damaging winds with only moderate mid-level downdrafts. As the evening progresses, expect a low level jet to increase a bit with some weak convergence into north central KS and a zone of more aggressive moisture transport from south central into northeast KS. This may further support north central KS thunderstorms by around 03Z, and could support further development into northeast KS by late evening and early morning. The chances are slight for thunderstorms at any given point, and the potential for severe weather overnight appears even lower yet given the expected elevated nature of the storms. Friday is a bit uncertain regarding temperatures and potential heat headlines. This is mainly due to uncertainty in how long any scattered precip or remnant cloud cover will be over the area. The current forecast leans toward a mainly cloud-free late morning and early afternoon. This, along with slightly warmer 850 temps would suggest temperatures near or slightly warmer than Thursday with dewpoints near or slightly lower than Thursday. IF this scenario plays out, a heat advisory could be needed for parts of the area again, but given at least some potential for convective debris and lower temps, have not issued at this time. Will then look to late afternoon for more potential for scattered storm development, mainly in northern KS. .LONG TERM...(Friday Night through Thursday) Issued at 356 PM CDT THU AUG 21 2014 The mid-level pattern is expected to remain fairly unchanged Friday night into the weekend as models show the mid-level ridge staying anchored over much of the southeastern U.S. with the mid-level trough in place over the western U.S. Friday night into Saturday this mid-level trough currently over the Pacific Northwest is expected to deepen and dig southward along the western Rockies before a strong embedded shortwave trough lifts northeastward toward the Northern Plains Saturday night into Sunday. As this shortwave trough pivots northward, it will help to slowly push the stationary front that will remain stalled out over north central Kansas and along the Kansas/Nebraska border eastward through the forecast area Sunday into Monday. Ahead of this frontal passage, southwesterly surface winds will prevail as surface low pressure remains anchored over the High Plains. As a result, warm air advection will persist through the weekend with unseasonably hot conditions. Highs for Saturday are expected to reach into the mid/upper 90s with afternoon heat indices rising into the 98F to 102F degree range. As winds shift to the north with the frontal passage, a slight cool-down is expected by early next week with highs in the upper 80s to low/mid 90s on Monday. As for precipitation chances through this period, there is a chance for some isolated nocturnal showers and thunderstorms Friday night and Saturday night with the help of the low-level jet, primarily focused over north central Kansas and along the Kansas/Nebraska border. Thunderstorm chances increase by Sunday night into Monday with the frontal passage. Models continue to show this front lifting northward over the region as a warm front by Monday night, however there are still some model discrepancies with regards to just how far north this warm front will lift. At this time though, models seem to be trending toward much of the southern half of the forecast area being in the warm sector as this boundary will likely become stationary once again near the Kansas/Nebraska border through Tuesday night, so expect temperatures to warm up once again into at least the low/mid 90s and possibly into the upper 90s for some locations. Tuesday night into Wednesday we may see a repeat of events as models are showing the stationary boundary once again transitioning to a cold front that will progress eastward across the region as a stronger mid-level trough develops and deepens across the Rockies. This stronger trough should help to finally push this system east of the area mid-week, with increased precipitation chances Tuesday night and Wednesday followed by slightly cooler temperatures in the mid 80s to near 90 degrees. && .AVIATION...(For the 00Z TAFs through 00Z Friday Evening) Issued at 611 PM CDT THU AUG 21 2014 Will continue with a VFR forecast expecting convection to remain mainly to the west and north of the terminals. Models show the surface trough axis remaining just west of the forecast area and the weak warm front along the state line remaining relatively stationary. Therefore think chances for TS in the terminals is slight at best. The boundary layer is expected to remain somewhat mixed once again tonight, so concerns for LLWS are minor but will monitor OBS for signs of the boundary layer decoupling this evening. && .TOP WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 9 PM CDT this evening FOR KSZ011-012-022>024- 026-038>040-054>056-058-059. && $$ UPDATE...Wolters SHORT TERM...Barjenbruch LONG TERM...Hennecke AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
558 PM CDT Wed Aug 20 2014 ...AVIATION UPDATE... .SHORT TERM...(This Evening through Thursday) Issued at 333 PM CDT WED AUG 20 2014 A broad upper level ridge axis will continue to amplify across the lower and mid MS river valley over the next 24 hours. A minor upper level trough was located across northeast OK and southeast KS this afternoon, on the western edge of the H5 ridge axis, and will move northeast across southeast KS into western MO this afternoon through early this evening. A shower did pop up across southern Coffey county but did dissipate. This minor H5 trough may provide just enough lift for an isolated shower or thunderstorms along and southeast of I-35 through the late afternoon and early evening hours. I will keep POPS at 14 percent due to the very isolated coverage. During the evening hours scattered thunderstorms will develop across western KS and eastern CO. Most of the thunderstorms will lift northeast into NE but the trailing edge of any thunderstorm complex may move across portions of north central and northeast KS late Tonight and through the mid morning hours of Thursday. At this time any thunderstorm complex that develops across western KS Tonight should be decaying through the early morning hours of Thursday, thus the thunderstorms will not be severe as they move northeast into a less favorable environment across northeast KS. Thursday will be mostly sunny as the H5 ridge axis amplifies across the southern and mid MS river valley. Thunderstorms should remain well west and north of the CWA during the daylight hours. Highs will warm into the mid to upper 90s once again. A few locations across the southwestern counties of the CWA may reach the 100 degree mark. Heat indices will warm into the 100 to 104 degree range during the afternoon hours. Some isolated areas across east central KS may see heat indices reach around 105 degrees. .LONG TERM...(Thursday Night through Wednesday) Issued at 333 PM CDT WED AUG 20 2014 The mid-level flow will remain fairly unchanged through the end of the week into the weekend with a broad ridge remaining in place across much of the central and eastern U.S. and a trough positioned over the western U.S. Thursday night through Saturday the models are in good agreement with the mid-level trough currently over the Pacific Northwest digging southward along the western Rockies with the ridge amplifying further northward toward the Great Lakes region. This pattern will keep southwesterly flow aloft across the region, which will continue to support warm air advection through the end of the week and into the weekend with 850MB temperatures reaching into the 23C-26C degree range. Hot and humid conditions are expected during that period as temperatures become unseasonably warm with highs reaching into the middle to upper 90s Friday and Saturday. These high temperatures combined with dewpoints reaching into the mid 60s to low 70s will result in afternoon heat indices soaring into the 100F to 104F degree range Friday and near 100F degrees on Saturday. We will continue to monitor these conditions closely to see if a heat advisory is needed for Friday. During this period, surface low pressure will become anchored across much of the Northern and Central Plains with a fairly stationary front situated near north central Kansas. There doesn`t appear to be much in the way of forcing along this boundary, however there may be scattered chances for precipitation from late week through the early weekend, especially across north central and northern Kansas. At this time, the better chances for precipitation look to be during the evening and overnight hours as the low-level jet increases over the region. Saturday night and Sunday, models show a strong embedded shortwave trough lifting northeastward across the northern Rockies and into the Northern Plains. This advancing shortwave should be enough to slowly push the stationary front eastward through the region Sunday night and Monday, so have more widespread chance PoPs during that period. This cold front may lift back northward across the area as a warm front, however there is model uncertainty with regards to how far north this warm front will lift, so confidence is low with precipitation chances Monday night through Wednesday. At this time have slight to low-end chance PoPs through that period. The frontal passage Sunday night into Monday will cause winds to shift to the north, providing a bit of relief to the heat with highs dropping into the middle 80s to low 90s Monday. Temperatures are more uncertain for Tuesday and Wednesday depending upon where the warm front is located and whether or not the region is situated within the warm sector, so have highs remaining in the upper 80s to low 90s at this time. && .AVIATION...(For the 00Z TAFs through 00Z Thursday Evening) Issued at 558 PM CDT WED AUG 20 2014 Organized convection appears to be a pretty low probability this evening with models showing the nose of the low level jet mainly north and east of the terminals. However will keep an eye on the convection off the higher terrain to the west and see if it is able to hold together once the boundary layer begins to cool. As for wind shear, think chances are to small to keep the mention of LLWS at TOP. RAP and NAM soundings are not as strong with the nocturnal inversion as the indicated last night and models prog a decent pressure gradient persisting through the night helping to keep the boundary layer from completely decoupling. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Gargan LONG TERM...Hennecke AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 AM CDT Wed Aug 20 2014 .SHORT TERM...(Today and Tonight) Issued at 234 AM CDT WED AUG 20 2014 Large-scale pattern over the Plains becoming more of a dirty ridge regime with at to somewhat above normal precipitable water levels across the bulk of the CONUS. Main troughs were over western North America and the Great Lakes, with a minor upper wave in east central Texas and 0Z observations showing a mid level trough over west Texas. Since last night at this time, warm air advection and deep moisture convergence has shifted northeast into Iowa where overnight convection has erupted. The Texas waves should be weakening with time with rather warm column leading to limited saturation despite modestly above normal PWs. Mid afternoon to evening hours exhibit little convective inhibition but hard to think anything more than isolated storms could result given limited forcing. Lower thermal fields showing overall little change from Tuesday, with even minor cooling suggested in some areas. Better mixing in the tighter surface gradient and mixing of the 30-40kt low level jet should more than offset any high cloud for highs to reach the mid to upper 90s again with heat index values a few degrees higher yet. A slightly stronger low level develops tonight, and with another day of heat today expect temps to only fall into the mid to upper 70s. .LONG TERM...(Thursday through Tuesday) Issued at 234 AM CDT WED AUG 20 2014 Thursday and Friday the heat continues across the forecast area as upper ridge slowly builds northward toward the upper Midwest. 850mb temps of 24-26c nose eastward out of the high plains into eastern Kansas which brings surface temperatures well into the upper 90s across most of the area. Longwave upper trof continues to move eastward into the northern Rockies, with shortwave trof moving into the upper Midwest late Thursday. Will keep low end pops across the KS NE border where trailing front and nocturnal llj may bring convection that far south although chances are better farther north. Similar scenario plays out again in the overnight hours Friday night. Subtle differences in the larger scale pattern influence the forecast through the weekend. EC is more pronounced with the upper ridge into eastern Kansas, while the GFS flattens the ridge more as energy moves out of the upper trof into the northern Plains. How far east clouds and rain chances can extend east and south will impact sensible weather through the weekend. Started to bring rain chances farther east and south by Sunday, which leans towards the GFS, but the strength of the ridge could certainly end up toward a warmer drier EC solution on Sunday. North central counties have better chances than farther east in this transition period. Hopefully by Monday into Tuesday the longwave trof will have made enough eastward progress to bring better rain chances and a cooling trend in temperatures to our area. Worth noting that both EC and GFS have a tropical system moving off the Mexico coast by the end of the forecast period, which would likely influence moisture transport into the longwave trof to its north and could help rain chances for the forecast area. Have a slow cooling in high temperatures from 90s on Saturday to low/middle 90s Sunday and back into the 80s for Monday and Tuesday. Increasing rain chances by Monday and Tuesday with overnight lows still on the warm side with 70s over the weekend to upper 60s by Monday night. && .AVIATION...(For the 06Z TAFs through 06Z Wednesday Night) Issued at 1136 PM CDT TUE AUG 19 2014 Models continue to depict the best convergence on the nose of the low level jet to stay just north and east of the forecast area. Therefore will maintain a VFR forecast. RAP and NAM forecast soundings continue to support the possibility for some LLWS and profiler data is starting to show the winds at 925MB strengthen. So will maintain the mention of wind shear. Additionally the RAP and NAM show a decent pressure gradient developing by Wednesday afternoon with dry adiabatic low level lapse rates and good mixing. Because of thin think south winds will become gusty by the afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...65 LONG TERM...67 AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1136 PM CDT Tue Aug 19 2014 ...AVIATION UPDATE... .SHORT TERM...(This Evening through Wednesday) Issued at 342 PM CDT TUE AUG 19 2014 An upper level trough was moving east across the upper Midwest and mid MS river valley late this afternoon. An upper level ridge across NM and CO will build east across the plains tonight and east into the lower and mid MS river valley by late Wednesday afternoon. Any convective complexes that form across the central and northern high plains this evening should move well north of the CWA tonight. Isentropic lift will cause elevated storms to form across southeast SD and eastern NE but these storms will move east into IA. Wednesday will be mostly sunny and warm as the upper level ridge axis moves east across the state of KS. Highs will reach the mid to upper 90s, with highs of 100 degrees possible across the southwest counties of the CWA. Deeper mixing across the western counties should cause dewpoints to drop into the mid 60s during the afternoon hours. The northeast counties may keep lower 70 dewpoints through the afternoon hours but high temperatures will be slightly cooler in the mid 90s. Heat indices will range from 100 to 104 degrees across the CWA during the afternoon hours. .LONG TERM...(Wednesday Night through Tuesday) Issued at 342 PM CDT TUE AUG 19 2014 The GFS is the only model hinting at clipping the far northwest county warning area with convection Wednesday night despite forecast soundings showing inhibition aloft through the night. Will therefore maintain a dry forecast through Thursday morning as the shortwave helping to develop precip should pass well north and west of the CWA. Another shortwave trough over the southern Rockies will move northeast and bring a chance for thunderstorms to the northwest third of the CWA Thursday night...although again the better chances will remain well north and west of the CWA. Following this wave...the ridging with the upper level high will undergo amplification as the stronger shortwave trough begins to rotate out of the case of the western trough and into the central/southern Rockies. Although this should keep the CWA dry and hot on Friday...it may allow for some of the high plains convection that forms late in the day to spread east and northeastward and briefly clip the CWA Friday night. Highs Thursday through Saturday will generally be in the middle to upper 90s. Models differ some with the overall timing/speed of the final shortwave to rotate out through the western trough and into the central plains next week. However they are similar in bringing the western trough slowly eastward into the ridge and gradually flattening it with time. This will result in one front moving into the CWA by Monday with a second arriving by Wednesday. This will keep the chances for showers and thunderstorms across most of the area Sunday thru Tuesday. With more clouds...precip chances and initial front...cooled high temperatures slightly for now into the 80s and lower 90s. At the same time...cooled lows in the middle 70s Thursday and Friday into the 60s by Monday and Tuesday. && .AVIATION...(For the 06Z TAFs through 06Z Wednesday Night) Issued at 1136 PM CDT TUE AUG 19 2014 Models continue to depict the best convergence on the nose of the low level jet to stay just north and east of the forecast area. Therefore will maintain a VFR forecast. RAP and NAM forecast soundings continue to support the possibility for some LLWS and profiler data is starting to show the winds at 925MB strengthen. So will maintain the mention of wind shear. Additionally the RAP and NAM show a decent pressure gradient developing by Wednesday afternoon with dry adiabatic low level lapse rates and good mixing. Because of thin think south winds will become gusty by the afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Gargan LONG TERM...63 AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
1032 PM EDT THU AUG 21 2014 .UPDATE... ISSUED AT 1031 PM EDT THU AUG 21 2014 A NEW FORECAST UPDATE WAS JUST SENT OUT ADDRESSING THE POSSIBILITY OF THUNDERSTORMS MOVING FURTHER SOUTH INTO OUR FORECAST AREA LATER TONIGHT THAN PREVIOUSLY THOUGHT. BASED ON CURRENT SATELLITE AND RADAR IMAGERY...IT APPEARS THAT THE NORTHERN 2 OR 3 TIERS OF COUNTIES OF OUR FORECAST AREA COULD EXPERIENCE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LARGE THUNDERSTORM COMPLEX THAT IS CURRENTLY MOVING ACROSS PARTS OF CENTRAL INDIANA AND WEST CENTRAL OHIO. THE SKY COVER...PRECIPITATION PROBABILITY...WEATHER TYPE...AND PRECIPITATION AMOUNT FORECAST GRIDS WERE ALL UPDATED TO REFLECT CURRENT TRENDS AND THE LATEST HRRR FORECAST DATA. THE HAZARDOUS WEATHER OUTLOOK WAS ALSO UPDATED TO REFLECT THE NEW THUNDERSTORM PROBABILITIES AND THE FURTHER SOUTHWARD MOVEMENT OF THE STORMS THEMSELVES. UPDATE ISSUED AT 758 PM EDT THU AUG 21 2014 SOME SIGNIFICANT UPDATES WERE MADE TO THE FORECAST GRIDS FOR THE REST OF THE TONIGHT INTO EARLY TOMORROW MORNING. WILL BE ISSUING A NEW ZONE FORECAST PRODUCT WITH THE PREFIRST PERIOD FROM DAY SHIFT REMOVED. THE GRIDS AND THE TEXT FORECAST PRODUCT HAVE BOTH BEEN UPDATED TO REFLECT THE FACT THAT ALL PRECIPITATION HAS NOW MOVED OUT OF EASTERN KENTUCKY. THE LATEST NAM12 AND HRRR MODELS BOTH ARE KEEPING PRECIPITATION OUT OF THE AREA UNTIL 8 OR 9Z TONIGHT. BASED ON THIS...AND THE LATEST RADAR IMAGERY...WHICH HAS A LARGE THUNDERSTORM COMPLEX MOVING ACROSS NORTHERN INDIANA...IT APPEARS THAT THE MODEL DATA IS ON TRACK AND THAT THE STORMS CURRENTLY MOVING ACROSS INDIANA WILL STAY MOSTLY NORTH OF THE AREA AS THEY MOVE ACROSS SOUTHERN OHIO LATE TONIGHT AND EARLY TOMORROW. WE MAY SEE A FEW SHOWERS AND STORMS FIRE UP ALONG THUNDERSTORM OUTFLOWS IN OUR NORTHERNMOST COUNTIES ALONG AND NORTH OF I-64 AROUND 8Z TONIGHT. THE SKY COVER GRIDS AND FORECAST WERE ALSO UPDATED TO REFLECT CURRENT TRENDS OF PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE FORECAST AREA. CONSIDERING THE AMOUNT OF RAIN EASTERN KENTUCKY HAS RECEIVED THE PAST SEVERAL DAYS...AND WITH CLOUDS BREAKING UP A BIT TONIGHT...WE SHOULD STILL SEE AREAS OF FOG IN OUR VALLEYS. LOCATIONS THAT RECEIVED RAINFALL TODAY...INCLUDING RIDGETOP LOCATIONS SUCH AS THE JACKSON WEATHER OFFICE...COULD ALSO SEE SOME MVFR FOG OVERNIGHT. THE HAZARDOUS WEATHER OUTLOOK WILL ALSO BE UPDATED SHORTLY TO REFLECT THE LACK OF THUNDER THROUGH DAWN TOMORROW. A NEW SET OF ZONES WILL ALSO BE ISSUED SHORTLY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU AUG 21 2014 STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 758 PM EDT THU AUG 21 2014 THIS EVENINGS TAFS WILL FEATURE A MOSTLY PRECIPITATION FREE OVERNIGHT PERIOD...WITH PARTLY TO MOSTLY CLOUDY SKIES...LIGHT WINDS...AND FOG. SJS COULD SEE SOME ISOLATED SHOWERS AND STORMS NEARBY FROM AROUND 8Z THROUGH 15 OR 16Z. JKL COULD BEGIN TO SEE SHOWERS AND STORMS IN THE AREA FROM 16Z ONWARD. LOZ AND SME SHOULD SEE ONLY ISOLATED SHOWERS AND STORMS FROM 16Z ONWARD. EXPECTING VFR CONDITIONS TO PREVAIL AT THE TAF SITES THROUGH AROUND 6Z TONIGHT. AFTER THAT THE TAFS WILL FEATURE MVFR FOG WITH SCT TO BKN MID AND HIGH LEVEL CLOUD COVER THROUGH 12 OR 13Z. THE FOG SHOULD BE GONE BY AROUND 9AM ON FRIDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
758 PM EDT THU AUG 21 2014 .UPDATE... ISSUED AT 758 PM EDT THU AUG 21 2014 SOME SIGNIFICANT UPDATES WERE MADE TO THE FORECAST GRIDS FOR THE REST OF THE TONIGHT INTO EARLY TOMORROW MORNING. WILL BE ISSUING A NEW ZONE FORECAST PRODUCT WITH THE PREFIRST PERIOD FROM DAY SHIFT REMOVED. THE GRIDS AND THE TEXT FORECAST PRODUCT HAVE BOTH BEEN UPDATED TO REFLECT THE FACT THAT ALL PRECIPITATION HAS NOW MOVED OUT OF EASTERN KENTUCKY. THE LATEST NAM12 AND HRRR MODELS BOTH ARE KEEPING PRECIPITATION OUT OF THE AREA UNTIL 8 OR 9Z TONIGHT. BASED ON THIS...AND THE LATEST RADAR IMAGERY...WHICH HAS A LARGE THUNDERSTORM COMPLEX MOVING ACROSS NORTHERN INDIANA...IT APPEARS THAT THE MODEL DATA IS ON TRACK AND THAT THE STORMS CURRENTLY MOVING ACROSS INDIANA WILL STAY MOSTLY NORTH OF THE AREA AS THEY MOVE ACROSS SOUTHERN OHIO LATE TONIGHT AND EARLY TOMORROW. WE MAY SEE A FEW SHOWERS AND STORMS FIRE UP ALONG THUNDERSTORM OUTFLOWS IN OUR NORTHERNMOST COUNTIES ALONG AND NORTH OF I-64 AROUND 8Z TONIGHT. THE SKY COVER GRIDS AND FORECAST WERE ALSO UPDATED TO REFLECT CURRENT TRENDS OF PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE FORECAST AREA. CONSIDERING THE AMOUNT OF RAIN EASTERN KENTUCKY HAS RECEIVED THE PAST SEVERAL DAYS...AND WITH CLOUDS BREAKING UP A BIT TONIGHT...WE SHOULD STILL SEE AREAS OF FOG IN OUR VALLEYS. LOCATIONS THAT RECEIVED RAINFALL TODAY...INCLUDING RIDGETOP LOCATIONS SUCH AS THE JACKSON WEATHER OFFICE...COULD ALSO SEE SOME MVFR FOG OVERNIGHT. THE HAZARDOUS WEATHER OUTLOOK WILL ALSO BE UPDATED SHORTLY TO REFLECT THE LACK OF THUNDER THROUGH DAWN TOMORROW. A NEW SET OF ZONES WILL ALSO BE ISSUED SHORTLY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU AUG 21 2014 STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 758 PM EDT THU AUG 21 2014 THIS EVENINGS TAFS WILL FEATURE A MOSTLY PRECIPITATION FREE OVERNIGHT PERIOD...WITH PARTLY TO MOSTLY CLOUDY SKIES...LIGHT WINDS...AND FOG. SJS COULD SEE SOME ISOLATED SHOWERS AND STORMS NEARBY FROM AROUND 8Z THROUGH 15 OR 16Z. JKL COULD BEGIN TO SEE SHOWERS AND STORMS IN THE AREA FROM 16Z ONWARD. LOZ AND SME SHOULD SEE ONLY ISOLATED SHOWERS AND STORMS FROM 16Z ONWARD. EXPECTING VFR CONDITIONS TO PREVAIL AT THE TAF SITES THROUGH AROUND 6Z TONIGHT. AFTER THAT THE TAFS WILL FEATURE MVFR FOG WITH SCT TO BKN MID AND HIGH LEVEL CLOUD COVER THROUGH 12 OR 13Z. THE FOG SHOULD BE GONE BY AROUND 9AM ON FRIDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
215 PM EDT WED AUG 20 2014 .UPDATE... ISSUED AT 1143 AM EDT WED AUG 20 2014 A RATHER CHALLENGING FORECAST THIS MORNING. TAIL END OF FRONTAL ZONE...BOUNDARY IS EVIDENT ACROSS THE MID WEST THIS MORNING AND WILL PLAY A MAJOR ROLE IN OUR WEATHER OVER THE NEXT SEVERAL DAYS. BUILDING RIDGE OF HIGH PRESSURE ALOFT AND TO OUR WEST WILL FORCE THIS BOUNDARY TO THE EAST OVER THE NEXT 24 HOURS. THIS BOUNDARY WILL BECOME INCREASINGLY ALIGNED WITH MID AND UPPER LEVEL FLOW PATTERNS AND BECOME STATIONARY ACROSS THE MID OHIO VALLEY REGION. THEREAFTER IT SERVES AS A FOCUS FOR CONVECTION AND THE OCCASIONAL CONVECTIVE COMPLEX OF STORMS. ATTM IT APPEARS AT LEAST PART OF OUR AREA WILL FEEL THE EFFECTS OF WEAK IMPULSES OF ENERGY RIDING OVER AND DROPPING DOWN ALONG THE EAST SIDE OF THE RIDGE AXIS. IMMEDIATE QUESTION IS WILL CURRENT UPSTREAM ACTIVITY OVER IA/IL MANAGE TO MAKE IT INTO OUR AREA. MOST LIKELY ANSWER LIES WITHIN THE SYNOPTIC PATTERN THAT IS TAKING SHAPE...BEST DESCRIBED AS AN ALMOST IDEAL MCS GENERATOR. MODELS SEEM TO HAVE PICKED UP ON THIS AS WELL... DEPICTING THE SOURCE OF MOISTURE/ENERGY...NAMELY BOUNDARY LAYER H925 TO H850 FLOW INTO THESE STORM COMPLEXES WEAKENING THROUGH THE DAY DUE TO DIURNAL MIXING...THE INCREASING AGAIN AT NIGHT. THESE COMPLEXES ONCE GENERATED THEN RIDE SOUTHEAST ALONG THE BOUNDARY. THAT BEING SAID EXPECT THE CURRENT ACTIVITY ACROSS IA/IL TO WEAKEN A BIT THROUGH THE DAY. BUT CONFIDENCE IS LOW THAT ACTIVITY WILL COME TO A COMPLETE END. MOST RECENT RUNS OF THE RAP AND HRRR SUPPORT THIS LINE OF THOUGHT AND REGIONAL SATELLITE DOES SHOW A DEFINITE WARMING TREND TO CLOUD TOPS ATTM. DECIDED TO TRIM POPS DOWN JUST A BIT THROUGH THE AFTERNOON BUT LEAVING ENOUGH TO TO ACCOUNT FOR ISOLD TO SCATTERED CONVECTION ASSOCIATED WITH DIURNAL HEATING AND ACTIVITY THAT MAY FIRE ALONG ANY RESIDUAL OUTFLOW BOUNDARIES. PREVIOUS FORECAST HAS POPS INCREASING AGAIN TONIGHT WHICH IS IN LINE WITH CURRENT THOUGHTS AS WELL...ESPECIALLY WITH THE SURFACE BOUNDARY SHIFTING TO THE EAST ACROSS OUR AREA. ALSO TWEAKED HOURLY TEMPS AND WINDS TO BRING THE GRIDS IN LINE WITH LATEST HOURLY OBS. FINALLY FRESHENED UP ZONES TO REMOVE MORNING FOG WORDING. UPDATE ISSUED AT 800 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE- DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 357 AM EDT WED AUG 20 2014 A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH. THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED. EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE FROM 85 TO 90 DEGREES. AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 335 AM EDT WED AUG 20 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST. CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL. THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND TUESDAY. IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 215 PM EDT WED AUG 20 2014 VERY JUICY AIR IN THE BOUNDARY LAYER IS RESPONSIBLE FOR LOW SC FIELD IN PLACE ACROSS THE AREA. CIGS HAVE GENERALLY BEEN WITHIN THE MVFR THRESHOLDS. WITH MIXING AND INCREASED HEATING...CLOUD BASE OF CU/SC FIELD SHOULD RISE JUST A BIT THROUGH THE AFTERNOON. OTHERWISE CONFIDENCE IS LOW ON EXACTLY HOW UPSTREAM STORM COMPLEX OVER IL/IN WILL AFFECT OUR AREA. MODEL GUIDANCE SUGGEST THE SYSTEM WILL FALL APART BEFORE ACTIVITY REDEVELOPS LATER TONIGHT ALONG A SURFACE FRONTAL BOUNDARY THAT WILL TRANSIT OUR AREA. FOLLOWED THIS TRAIN OF THOUGHT PRETTY CLOSELY FOR THE FORECAST. IN ADDITION...GUIDANCE IS HITTING FOG ACROSS THE AREA PRETTY HARD TONIGHT. BUT WITH EXTENSIVE CLOUD COVER MOVING BACK INTO THE AREA TENDENCY WAS TO GO MORE OPTIMISTIC. VERY WEAK UPPER LEVEL DISTURBANCE WILL APPROACH BETWEEN 06 AND 12Z...AND BE THE CATALYST FOR THE AFOREMENTIONED RENEWED CONVECTIVE THREAT. THEREAFTER...THE SURFACE FRONTAL BOUNDARY WILL BECOME STATIONARY TO OUR EAST AND BECOME THE FOCUS OF ADDITIONAL SHOWERS AND THUNDERSTORMS OVER THE NEXT SEVERAL DAYS. WINDS WILL BE LIGHT AND GENERALLY FROM THE WEST SOUTHWEST THROUGH THE FORECAST PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...RAY SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN/RAY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
137 PM EDT Wed Aug 20 2014 ...Updated Forecast and Aviation Discussions... ...Forecast Update... Issued at 135 PM EDT Wed Aug 20 2014 Complex across central Illinois is holding together fairly well early this afternoon. Have a pretty thick canopy of cirrus out ahead of the storms, but it may hold together enough as it moves into our forecast area. High-res models are not too gung ho about rain chances in this area this afternoon, but with a very unstable surface-based atmosphere in our region, SPC mesoanalysis has 4-6 k CAPEs, just cannot rule out storms developing/maintaining. Have shifted the highest pop axis a little south, to a Huntingburg, IN to Danville, KY line. Will continue to watch incoming pattern for updates through the afternoon. Issued at 1135 AM EDT Wed Aug 20 2014 Partly cloudy skies were noted across southern Indiana and central Kentucky this morning. Temperatures ranged from the upper 70s to near 80- in the east/northeast with lower 80s generally in the I-65 corridor and points west. From the KY Mesonet data and visible satellite imagery, there appears to be boundary draped across the southern part of the forecast area. This evident in the dewpoint readings across southern KY which are in the middle 70s with only upper 60s to lower 70s across our NE sections. A decaying MCS over central IL will continue to spread mid-high level cloudiness down into mainly western KY this afternoon. These clouds along with the boundary in the region may serve as a focus for convective development later this afternoon. The high resolution convection allowing models have vastly different solutions. The latest runs of the HRRR keep much of our region dry thought the day with convection mainly developing out to our west. While the NSSL WRF ARW runs develop convection up near CVG and drop it SE into WFO JKL`s region. The mixed signals in the guidance make this forecast particularly challenging this afternoon. For now, have kept the current forecast on track. Current thinking is that convection will probably start to develop over the next few hours along the left over boundary...given multiple convectively induced lifting mechanisms cross the region. Damaging winds and perhaps some large hail will be possible with the storms this afternoon as moderate instability combined with around 30 kts of WNW flow aloft will be in place across the region. .SHORT TERM (Now through Thursday)... Issued at 340 AM EDT Wed Aug 20 2014 A complex short term forecast is in store with multiple rounds of strong to potentially severe convection possible as potent shortwaves topple a central CONUS ridge and dive southeast into the Ohio Valley. In addition, the eastern edge of a warm front will slowly lift north over the region over the next few days providing focus for convection. Also left over boundaries from storms will provide focus for renewed convection over the next few days with convective activity peaking during the afternoon and evening hours during best instability. As of 315am this morning, convection over the Bluegrass region was causing mainly very heavy rainfall and lots of lightning. A flood advisory is effect for northern Harrison County KY through 6am this morning due to training storms over that area. The Harrison County mesonet has received 1.34 inches of rain so far with impressive rainfall rates which may cause minor flooding issues. Think that this complex of storms will move east of the area within the next 1-2 hrs and we may see a dry period through the morning hours. Expect a left over boundary from convection over central Indiana yesterday evening to settle somewhere near the Ohio River over portions of southern Indiana and north central Kentucky. Believe this boundary will be key for redevelopment of convection this afternoon. Most short range models indicate a shortwave will dive south into the area this evening. Ahead of this wave, expect the atmosphere to become very unstable with only partly cloudy skies in the wake of morning convection. Bulk shear will increase ahead of the wave as early as 1-3pm this afternoon. This is when we may see convection begin to fire in the region of the left over sfc boundary. Convection should be enhanced in strength and coverage during the evening hours as the shortwave passes through. It is a bit unclear how long into the evening and overnight hours convection will continue. It may survive for a prolonged period of time if a good cold pool and outflow boundaries get going. At some point late tonight into tomorrow morning expect a break in showers/storms. Another notable shortwave looks to impact mainly northern KY and southern Indiana with storms for Thurs afternoon/evening as well. Models generally do not have a good handle on ongoing convection and evolution so confidence is rather low on exact timing. However, model soundings indicate increased bulk shear values with each wave and excellent instability so storms will likely be strong to severe in nature today through Thurs with damaging winds, large hail, and torrential rainfall all possible. PWATs will hover in the 1.6-2 inch range resulting in some heavy rainers and potential flood problems. As for temperatures, think that highs will range from the upper 80s to lower 90s today and tomorrow with locations west of I-65 likely seeing max heat indices near 100 each afternoon. Low temperatures tonight will be mild in the lower 70s. .LONG TERM (Thursday night through Tuesday)... Issued at 311 AM EDT Wed Aug 20 2014 Thursday night through Tuesday... Expect a hot spell throughout the entire extended period, at least through the middle portion of next week. In an upper air pattern that we`ve not seen much of this summer, strong 500mb ridging will develop initially across the lower Mississippi Valley by Thursday evening, with longwave troughs located over the Pacific Northwest and New England. The wavelength of this trough-ridge-trough pattern will lead to a stagnant pattern. The GFS for example holds this ridge in place through at least late Monday, building it northwards towards the Commonwealth. We should expect probably a week`s worth of hot sticky humid weather with highs well into the 90s and warm overnight lows in the lower to mid 70s over the weekend and into the middle of next week. Rising Heat Indices may be a concern for early next week. In this type of pattern, shortwaves moving along the periphery of 500mb ridging can bring episodic convection. Initially, Thursday night through Sunday, scattered thunderstorms may develop within a northwest flow pattern along the northeastern edge of this building ridge. This would favor southeastern Indiana, southern Ohio and the northern Bluegrass for possible scattered thunderstorms, concentrated during the afternoon and evening hours. Southwestern Kentucky, closer to the warm temperatures aloft associated with this ridge, will likely stay dry. By Monday and Tuesday, think the entire region will be dry, as ridging builds northwards into the Commonwealth. && .AVIATION (18Z TAF Update)... Issued at 125 PM EDT Wed Aug 20 2014 Confidence in convective forecast this period is low, as cirrus shield from storms to our northwest quickly moves into the region. Have some cumulus developing over the central forecast area this hour, and SPC mesoanalysis indicates plenty of instability across the region. However, the cirrus canopy should provide some subsidence to inhibit convection. There is still a possibility that the storms to our northwest can remain organized enough to bring those storms to the terminals later this afternoon. Thus have gone with vicinity storms over a larger period of time and will update as the afternoon progresses. May even get into another round of precip later tonight, as additional disturbances move in from the northwest, but a lot will depend on what happens this afternoon. Fog forecast for Thursday morning will depend on that as well. Given very high dewpoints across BWG this hour, have enough confidence to go with a period of MVFR conditions, as in current guidance. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Updates........MJ/RJS Short Term.....AMS Long Term......JSD Aviation.......RJS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1143 AM EDT WED AUG 20 2014 .UPDATE... ISSUED AT 1143 AM EDT WED AUG 20 2014 A RATHER CHALLENGING FORECAST THIS MORNING. TAIL END OF FRONTAL ZONE...BOUNDARY IS EVIDENT ACROSS THE MID WEST THIS MORNING AND WILL PLAY A MAJOR ROLE IN OUR WEATHER OVER THE NEXT SEVERAL DAYS. BUILDING RIDGE OF HIGH PRESSURE ALOFT AND TO OUR WEST WILL FORCE THIS BOUNDARY TO THE EAST OVER THE NEXT 24 HOURS. THIS BOUNDARY WILL BECOME INCREASINGLY ALIGNED WITH MID AND UPPER LEVEL FLOW PATTERNS AND BECOME STATIONARY ACROSS THE MID OHIO VALLEY REGION. THEREAFTER IT SERVES AS A FOCUS FOR CONVECTION AND THE OCCASIONAL CONVECTIVE COMPLEX OF STORMS. ATTM IT APPEARS AT LEAST PART OF OUR AREA WILL FEEL THE EFFECTS OF WEAK IMPULSES OF ENERGY RIDING OVER AND DROPPING DOWN ALONG THE EAST SIDE OF THE RIDGE AXIS. IMMEDIATE QUESTION IS WILL CURRENT UPSTREAM ACTIVITY OVER IA/IL MANAGE TO MAKE IT INTO OUR AREA. MOST LIKELY ANSWER LIES WITHIN THE SYNOPTIC PATTERN THAT IS TAKING SHAPE...BEST DESCRIBED AS AN ALMOST IDEAL MCS GENERATOR. MODELS SEEM TO HAVE PICKED UP ON THIS AS WELL... DEPICTING THE SOURCE OF MOISTURE/ENERGY...NAMELY BOUNDARY LAYER H925 TO H850 FLOW INTO THESE STORM COMPLEXES WEAKENING THROUGH THE DAY DUE TO DIURNAL MIXING...THE INCREASING AGAIN AT NIGHT. THESE COMPLEXES ONCE GENERATED THEN RIDE SOUTHEAST ALONG THE BOUNDARY. THAT BEING SAID EXPECT THE CURRENT ACTIVITY ACROSS IA/IL TO WEAKEN A BIT THROUGH THE DAY. BUT CONFIDENCE IS LOW THAT ACTIVITY WILL COME TO A COMPLETE END. MOST RECENT RUNS OF THE RAP AND HRRR SUPPORT THIS LINE OF THOUGHT AND REGIONAL SATELLITE DOES SHOW A DEFINITE WARMING TREND TO CLOUD TOPS ATTM. DECIDED TO TRIM POPS DOWN JUST A BIT THROUGH THE AFTERNOON BUT LEAVING ENOUGH TO TO ACCOUNT FOR ISOLD TO SCATTERED CONVECTION ASSOCIATED WITH DIURNAL HEATING AND ACTIVITY THAT MAY FIRE ALONG ANY RESIDUAL OUTFLOW BOUNDARIES. PREVIOUS FORECAST HAS POPS INCREASING AGAIN TONIGHT WHICH IS IN LINE WITH CURRENT THOUGHTS AS WELL...ESPECIALLY WITH THE SURFACE BOUNDARY SHIFTING TO THE EAST ACROSS OUR AREA. ALSO TWEAKED HOURLY TEMPS AND WINDS TO BRING THE GRIDS IN LINE WITH LATEST HOURLY OBS. FINALLY FRESHENED UP ZONES TO REMOVE MORNING FOG WORDING. UPDATE ISSUED AT 800 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE- DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 357 AM EDT WED AUG 20 2014 A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH. THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED. EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE FROM 85 TO 90 DEGREES. AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 335 AM EDT WED AUG 20 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST. CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL. THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND TUESDAY. IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 815 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT OFF TO THE SOUTHEAST IN THE NEXT HOUR OR TWO. IFR/LIFR FOG WILL LIFT OUT IN THE NEXT HOUR...WITH A RETURN TO VFR CONDITIONS THROUGH THE REST OF THE DAY. SOME ISOLATED TO SCATTERED CONVECTION WILL THREATEN AGAIN THIS AFTERNOON...BUT COVERAGE IS EXPECTED TO BE LIMITED ENOUGH TO ONLY MENTION VCTS FOR NOW. FOG WILL LIKELY RETURN AFTER 06Z TONIGHT...HOWEVER ANOTHER UPPER LEVEL DISTURBANCE WILL LIKELY APPROACH BETWEEN 06 AND 12Z...BRINGING IN ADDITIONAL CLOUD COVER AND ALSO RENEWING THE CONVECTIVE THREAT. THIS WILL LIKELY KEEP THE FOG FROM BECOMING TOO DENSE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...RAY SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
ISSUED BY NATIONAL WEATHER SERVICE PADUCAH KY 1138 AM EDT Wed Aug 20 2014 ...Forecast Update... Issued at 1135 AM EDT Wed Aug 20 2014 Partly cloudy skies were noted across southern Indiana and central Kentucky this morning. Temperatures ranged from the upper 70s to near 80- in the east/northeast with lower 80s generally in the I-65 corridor and points west. From the KY Mesonet data and visible satellite imagery, there appears to be boundary draped across the southern part of the forecast area. This evident in the dewpoint readings across southern KY which are in the middle 70s with only upper 60s to lower 70s across our NE sections. A decaying MCS over central IL will continue to spread mid-high level cloudiness down into mainly western KY this afternoon. These clouds along with the boundary in the region may serve as a focus for convective development later this afternoon. The high resolution convection allowing models have vastly different solutions. The latest runs of the HRRR keep much of our region dry thought the day with convection mainly developing out to our west. While the NSSL WRF ARW runs develop convection up near CVG and drop it SE into WFO JKL`s region. The mixed signals in the guidance make this forecast particularly challenging this afternoon. For now, have kept the current forecast on track. Current thinking is that convection will probably start to develop over the next few hours along the left over boundary...given multiple convectively induced lifting mechanisms cross the region. Damaging winds and perhaps some large hail will be possible with the storms this afternoon as moderate instability combined with around 30 kts of WNW flow aloft will be in place across the region. .SHORT TERM (Now through Thursday)... Issued at 340 AM EDT Wed Aug 20 2014 A complex short term forecast is in store with multiple rounds of strong to potentially severe convection possible as potent shortwaves topple a central CONUS ridge and dive southeast into the Ohio Valley. In addition, the eastern edge of a warm front will slowly lift north over the region over the next few days providing focus for convection. Also left over boundaries from storms will provide focus for renewed convection over the next few days with convective activity peaking during the afternoon and evening hours during best instability. As of 315am this morning, convection over the Bluegrass region was causing mainly very heavy rainfall and lots of lightning. A flood advisory is effect for northern Harrison County KY through 6am this morning due to training storms over that area. The Harrison County mesonet has received 1.34 inches of rain so far with impressive rainfall rates which may cause minor flooding issues. Think that this complex of storms will move east of the area within the next 1-2 hrs and we may see a dry period through the morning hours. Expect a left over boundary from convection over central Indiana yesterday evening to settle somewhere near the Ohio River over portions of southern Indiana and north central Kentucky. Believe this boundary will be key for redevelopment of convection this afternoon. Most short range models indicate a shortwave will dive south into the area this evening. Ahead of this wave, expect the atmosphere to become very unstable with only partly cloudy skies in the wake of morning convection. Bulk shear will increase ahead of the wave as early as 1-3pm this afternoon. This is when we may see convection begin to fire in the region of the left over sfc boundary. Convection should be enhanced in strength and coverage during the evening hours as the shortwave passes through. It is a bit unclear how long into the evening and overnight hours convection will continue. It may survive for a prolonged period of time if a good cold pool and outflow boundaries get going. At some point late tonight into tomorrow morning expect a break in showers/storms. Another notable shortwave looks to impact mainly northern KY and southern Indiana with storms for Thurs afternoon/evening as well. Models generally do not have a good handle on ongoing convection and evolution so confidence is rather low on exact timing. However, model soundings indicate increased bulk shear values with each wave and excellent instability so storms will likely be strong to severe in nature today through Thurs with damaging winds, large hail, and torrential rainfall all possible. PWATs will hover in the 1.6-2 inch range resulting in some heavy rainers and potential flood problems. As for temperatures, think that highs will range from the upper 80s to lower 90s today and tomorrow with locations west of I-65 likely seeing max heat indices near 100 each afternoon. Low temperatures tonight will be mild in the lower 70s. .LONG TERM (Thursday night through Tuesday)... Issued at 311 AM EDT Wed Aug 20 2014 Thursday night through Tuesday... Expect a hot spell throughout the entire extended period, at least through the middle portion of next week. In an upper air pattern that we`ve not seen much of this summer, strong 500mb ridging will develop initially across the lower Mississippi Valley by Thursday evening, with longwave troughs located over the Pacific Northwest and New England. The wavelength of this trough-ridge-trough pattern will lead to a stagnant pattern. The GFS for example holds this ridge in place through at least late Monday, building it northwards towards the Commonwealth. We should expect probably a week`s worth of hot sticky humid weather with highs well into the 90s and warm overnight lows in the lower to mid 70s over the weekend and into the middle of next week. Rising Heat Indices may be a concern for early next week. In this type of pattern, shortwaves moving along the periphery of 500mb ridging can bring episodic convection. Initially, Thursday night through Sunday, scattered thunderstorms may develop within a northwest flow pattern along the northeastern edge of this building ridge. This would favor southeastern Indiana, southern Ohio and the northern Bluegrass for possible scattered thunderstorms, concentrated during the afternoon and evening hours. Southwestern Kentucky, closer to the warm temperatures aloft associated with this ridge, will likely stay dry. By Monday and Tuesday, think the entire region will be dry, as ridging builds northwards into the Commonwealth. && .AVIATION (12Z TAF Update)... Issued at 650 AM EDT Wed Aug 20 2014 The main TAF concerns will be brief MVFR restrictions this morning and convection timing. MVFR cigs have worked into LEX this morning and expect them to remain for the next few hours. Low clouds are also close to SDF but think that they will remain just north of the terminal this morning. BWG could see some light br but the window is quickly closing for any MVFR restrictions so will keep them VFR this morning. This evening a convective complex is expected to develop to our northwest and dive south/southeast into the area. Ahead of this complex of storms, additional cells may form over central KY. Felt confident enough to include VCTS at the TAF sites for this issuance as models have been persistent with this round of convection. However, timing may need to be adjusted throughout the day today. Winds will remain southerly through the TAF period generally 7 kts or less except in t-storms. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........MJ Short Term.....AMS Long Term......JSD Aviation.......AMS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
815 AM EDT WED AUG 20 2014 .UPDATE... ISSUED AT 800 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT SOUTHEASTERN KENTUCKY IN THE NEXT ONE TO TWO HOURS. ONCE THESE STORMS CLEAR THE AREA...THERE MAY BE SOME ISOLATED TO SCATTERED CONVECTION RE- DEVELOPING ACROSS EASTERN KENTUCKY THIS AFTERNOON DURING PEAK HEATING. WILL STAY THE COURSE AND CONTINUE TO MENTION THE POPS...HOWEVER SOME OF THE GUIDANCE HAS TRENDED DRIER...AND GIVEN THE SUBSIDENCE FOLLOWING THE DEPARTING WAVE...WOULD NOT BE SURPRISED IF CONVECTION IS EVEN MORE ISOLATED. UPDATES HAVE BEEN SENT. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 357 AM EDT WED AUG 20 2014 A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH. THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED. EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE FROM 85 TO 90 DEGREES. AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 335 AM EDT WED AUG 20 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST. CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL. THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND TUESDAY. IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 815 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL EXIT OFF TO THE SOUTHEAST IN THE NEXT HOUR OR TWO. IFR/LIFR FOG WILL LIFT OUT IN THE NEXT HOUR...WITH A RETURN TO VFR CONDITIONS THROUGH THE REST OF THE DAY. SOME ISOLATED TO SCATTERED CONVECTION WILL THREATEN AGAIN THIS AFTERNOON...BUT COVERAGE IS EXPECTED TO BE LIMITED ENOUGH TO ONLY MENTION VCTS FOR NOW. FOG WILL LIKELY RETURN AFTER 06Z TONIGHT...HOWEVER ANOTHER UPPER LEVEL DISTURBANCE WILL LIKELY APPROACH BETWEEN 06 AND 12Z...BRINGING IN ADDITIONAL CLOUD COVER AND ALSO RENEWING THE CONVECTIVE THREAT. THIS WILL LIKELY KEEP THE FOG FROM BECOMING TOO DENSE. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
357 AM EDT WED AUG 20 2014 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 357 AM EDT WED AUG 20 2014 A COMPLEX OF SHOWERS AND THUNDERSTORMS IS CURRENTLY SLIDING EAST ACROSS THE OHIO VALLEY ASSOCIATED WITH A PASSING SHORT WAVE TROUGH. THE MORE ORGANIZED PORTION OF THIS COMPLEX HAS BEEN CONFINED TO ALONG AND NORTH OF THE MOUNTAIN PARKWAY. THE HRRR MODEL HAS NOT BEEN HANDLING THIS FEATURE WELL THROUGH THE OVERNIGHT...OVERPLAYING THE DEVELOPMENT TO THE SOUTH THAT HAS BEEN WEAK IN REALITY...WHILE UNDERPLAYING WHERE CONVECTION HAS BEEN MORE ORGANIZED AND SUSTAINED. EXPECT THIS COMPLEX TO KEEP MOVING EAST...AFFECTING LOCATIONS ALONG AND NORTH OF THE MOUNTAIN PARKWAY FOR THE NEXT FEW HOURS...BEFORE EXITING THE AREA BY 12Z. THERE WILL BE SOME SUBSIDENCE FOLLOWING THIS DEPARTING SHORT WAVE FOR TODAY WORKING IN FROM WEST TO EAST...SO HAVE TRIMMED THE POPS BACK A BIT...PEAKING IN THE 20 TO 30 RANGE FOR MOST LOCATIONS DURING THE HOTTER PART OF THE DAY. HIGHS TODAY WILL RANGE FROM 85 TO 90 DEGREES. AS WE HEAD INTO TONIGHT...CONVECTION WILL BE ON THE DOWNWARD TREND THROUGH 06Z...BUT THEN LOOKS TO INCREASE BETWEEN 06 AND 12Z...AS ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE NORTHWEST. POP CHANCES WILL CONTINUE TO INCREASE THROUGH THE DAY ON THURSDAY WITH HEATING AIDING THE MODEST FORCING FROM THE PASSING SHORT WAVE. HAVE MAINTAINED THE BETTER POPS IN THE NORTHEAST...AND LESSER VALUES IN THE SOUTHWEST...FURTHER REMOVED FROM THE BETTER FORCING. HIGHS WILL RETURN TO THE 85 TO 90 DEGREE RANGE IN THE SOUTHWEST...WITH MID 80S IN THE NORTHEAST...WHERE MORE PERSISTENT CLOUD COVER WILL RESIDE. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 335 AM EDT WED AUG 20 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON THURSDAY NIGHT WITH A SLOWLY BUILDING RIDGE OVER THE CENTRAL CONUS AND DIGGING TROUGHS OVER THE NORTHWEST AND NORTHEAST. THIS GENERAL TREND CONTINUES THROUGH THE ENTIRE EXTENDED PERIOD. DURING THIS PERIOD...QUITE A FEW STRONG SHORTWAVES TRAVEL OVER THE BUILDING RIDGE IN THE CENTRAL PLAINS AND INTO THE OH VALLEY AND GREAT LAKES REGION. THE FIRST WAVE OF NOTE WILL BE THE SHORTWAVE MOVING THROUGH AT THE BEGINNING OF THE EXTENDED. AFTER THIS...THE PATTERN TURNS INTO A MORE MCS DRIVEN PATTERN FRIDAY THROUGH SUNDAY WITH ACTIVITY CENTERED AROUND WHAT THE DAYS CONVECTION BRINGS AND IS DIURNALLY AFFECTED. THROUGH THE PERIOD THE UPPER RIDGE SLOWLY WEAKENS AND DRIFTS EAST. CONCERNING THE MODELS DURING THE EXTENDED...THE GFS AND EURO LOOK TO BE RIGHT ON TRACK AND IN GOOD AGREEMENT. THOUGH...THE EURO LOOKS TO CUT OFF ANY CONVECTION BY THE END OF THE EXTENDED AS THE RIDGE AXIS SETS UP RIGHT OVER EASTERN KENTUCKY LEADING TO AN END TO ALL DIURNALLY DRIVEN CONVECTION AND DISPLACING THE TRACK OF THE MCS MORE TO THE NORTHEAST. BASED ON THE GOOD AGREEMENT...IT SEEMS TO BE A GOOD CONSENSUS TO STAY CLOSE TO THE SOLUTION OF THE ALL BLEND MODEL. THOUGH DEPENDING ON WHAT THE 00Z EURO DOES ON THE MONDAY AND TUESDAY TIME FRAME FOR THE RIDGE AXIS RIGHT OVER THE AREA...MAY DROP POPS BELOW THE ALL MODEL BLEND SOLUTION. WITH THE SOLUTION OF THE ALL MODEL BLEND...THE BEST CHANCE OF POPS WILL BE DURING THE FRIDAY THROUGH SUNDAY TIME FRAME AND LESS DURING THE MONDAY AND TUESDAY TIME FRAME WHERE THE RIDGE WILL BE OVER EASTERN KENTUCKY AND HAVE LEFT SLIGHT CHANCE MAINLY DURING THE AFTERNOON ON MONDAY AND TUESDAY. IN ADDITION TO THIS PATTERN...TEMPERATURES WILL BE ON THE INCREASE IN EARNEST AS SOME OF THE WARMEST WEATHER OF THE ENTIRE SUMMER WILL BEGIN TO SET IN FROM FRIDAY THROUGH THE REST OF THE EXTENDED. HIGH TEMPERATURES WILL SURPASS 90 DEGREES IN SOME AREAS OF EASTERN KENTUCKY AND HUMIDITY WILL BE ON THE INCREASE AS WELL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 235 AM EDT WED AUG 20 2014 SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL WORK THEIR WAY FROM WEST TO EAST ACROSS EASTERN KENTUCKY THROUGH DAWN. AREAS ALONG AND NORTH OF THE I-64 CORRIDOR WILL SEE THE BEST CHANCE OF THE MORE CONCENTRATED CONVECTION. AS SUCH...HAVE HANDLED MOST OF THIS ACTIVITY WITH VCTS/VCSH AS SOME OF THIS ACTIVITY WILL LIKELY WEAKEN AS IT HEADS EAST. EXPECT MVFR/IFR FOG TO SET IN BETWEEN 08 AND 12Z AS WELL...WITH THE DEEPER RIVER VALLEYS ALONG WITH ANY LOCATIONS THAT SEE MORE SUSTAINED RAINFALL SEEING IFR OR WORSE FOG. THERE SHOULD BE A CONVECTIVE LULL IN THE MORNING...BEFORE SOME ISOLATED STORMS MAY THREATEN AGAIN IN THE AFTERNOON. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS CARIBOU ME
931 PM EDT THU AUG 21 2014 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY BUILD DOWN ACROSS THE AREA THROUGH THE COMING WEEKEND. && .NEAR TERM /THROUGH FRIDAY/... 931 PM UPDATE...AN UPPER LOW WILL SLOWLY WORK ACROSS MAINE OVERNIGHT AND INTO THE NORTHERN GULF OF MAINE BY FRI EVENING. THERE ARE A FEW SHOWERS UNDERNEATH THE LOW THAT STRETCH FROM PARTS OF DOWNEAST MAINE INTO THE WESTERN MOUNTAINS. THE NEAR TERM MODELS SUCH AS THE HRRR AND RUC KEEP SOME SHOWERS IN THIS AREA THE REMAINDER OF THE NIGHT...AND ALSO DEVELOP SOME SHOWERS IN THE ST JOHN VALLEY WELL AFTER MIDNIGHT. MADE SOME MINOR ADJUSTMENTS TO THE GRIDS BASED ON THE LATEST OBSERVATIONS...SATELLITE PICTURES...RADAR...AND NEAR TERM MODEL TRENDS. PREVIOUS DISCUSSION... A COMPLEX WEATHER PATTERN FEATURING SUBTLE FEATURES IN THE UPPER LEVELS WILL BRING SOME MINOR FORECAST CHALLENGES DURING THE NEXT 24 HOURS. A VERY WEAK UPPER LEVEL LOW WILL STRAY ACROSS DOWNEAST AREAS TONIGHT INTO FRIDAY. MOISTURE ASSOCIATED WITH THIS UPPER LOW COMBINED WITH WEAK UPSLOPE WINDS FROM HIGH PRESSURE BUILDING DOWN FROM THE NORTH WILL BRING CLOUDS AND SOME ISOLATED SHOWERS TO DOWNEAST AREAS TONIGHT AND EARLY FRIDAY, MAINLY ACROSS INTERIOR WESTERN SPOTS. SOUNDING FORECASTS SHOW SOME WEAK CAPE, AROUND 300 J/KG, OVER SOME OF THE HIGHER ELEVATIONS IN PISCATAQUIS COUNTY. THIS MAY RESULT IN SOME CONVECTIVE SHOWERS AND POSSIBLY A VERY ISOLATED THUNDERSTORM. THE LARGE HIGH PRESSURE SYSTEM TO OUR NORTH IS STILL EXPECTED TO SLOWLY PRESS SOUTH INTO THE REGION. THIS HIGH WILL ALLOW SKIES TO BE PARTLY CLOUDY OVER THE NORTH AND COULD BRING PARTIAL CLEARING TO CENTRAL AREAS LATE ON FRIDAY. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... HIGH PRESSURE BUILDS IN FRIDAY NIGHT HOWEVER AS THE FLOW WILL BE FROM THE NORTHEAST THIS WILL BRING THE POTENTIAL FOR SOME STRATUS AND FOG. ANY CLOUDS/FOG WILL QUICKLY BURN OFF SATURDAY MORNING WITH AN OTHERWISE FAIR WEEKEND EXPECTED UNDER PARTLY TO MOSTLY SUNNY SKIES. TEMPERATURES WILL BE NEAR SEASONAL FOR SATURDAY AND BEGIN TO WARM UP FOR SUNDAY AWAY FROM THE COAST. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... WARM LATE SUMMER WEATHER WILL BE THE BIG STORY FOR THE BEGINNING TO MIDDLE OF NEXT WEEK. A HIGH CENTERED OVER THE AREA EARLY IN THE PERIOD WILL GRADUALLY GIVE WAY TO WESTERLY FLOW TOWARD THE MIDDLE OF THE WEEK, WITH PERHAPS SOMEWHAT INCREASED AFTERNOON/EVENING THUNDERSTORM CHANCES AROUND THE WEDNESDAY/THURSDAY TIME FRAME, BUT STILL LIKELY DRY SUNDAY THROUGH TUESDAY. EXPECT WIDESPREAD LOW TO MID 80S MONDAY THROUGH WEDNESDAY, EXCEPT COOLER 70S NEAR THE COAST. WE CONTINUED TO GO CLOSER TO THE CONSENSUS OF RAW MODEL OUTPUT OVER MOS GUIDANCE FOR HIGHS, AS 925 MB AND 850 MB TEMPERATURES JUSTIFY GOING WARMER THAN MOS, WHICH TRENDS TOWARD CLIMATOLOGY IN THE EXTENDED. FORECAST MODELS ARE IN GOOD AGREEMENT THROUGH TUESDAY, BUT BEGIN TO HAVE ISSUES AROUND WEDNESDAY AS TO WHETHER WE GET A COLD FRONTAL PASSAGE FROM THE NORTHWEST AT THAT TIME OR STAY IN THE WARM WEST/SOUTHWEST FLOW FOR A BIT LONGER. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... NEAR TERM: GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MIDNIGHT TONIGHT. CONDITIONS MAY BRIEFLY LOWER TO MVFR LATE TONIGHT AND POSSIBLY IFR DOWNEAST. CONDITIONS SHOULD THEN IMPROVE TO VFR AT MOST SITES BY LATE MORNING FRIDAY. SHORT TERM: MVFR WILL BE POSSIBLE OVERNIGHT FRIDAY NIGHT DUE TO THE POTENTIAL FOR SOME STRATUS AND FOG..ESPECIALLY FOR THE NORTHERN SITES. OTHERWISE EXPECT VFR THROUGH THE PERIOD. && .MARINE... NEAR TERM: WINDS WILL REMAIN LIGHT THROUGH FRIDAY AS HIGH PRESSURE SLOWLY BUILDS DOWN FROM THE NORTH. SHORT TERM: CONDITIONS WILL REMAIN RELATIVELY TRANQUIL ON THE WATERS WITH NO HEADLINES EXPECTED THROUGH EARLY NEXT WEEK. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...BLOOMER/CB SHORT TERM...FITZSIMMONS LONG TERM...FITZSIMMONS AVIATION...BLOOMER/CB/FITZSIMMONS MARINE...BLOOMER/CB/FITZSIMMONS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
953 PM EDT THU AUG 21 2014 .SYNOPSIS... A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY ACROSS THE AREA INTO THE UPCOMING WEEKEND. HIGH PRESSURE FROM NEW ENGLAND IS SLOW TO BUILD OVER THE REGION FROM SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... UPDATE THIS EVENING TO MAKE MINOR TWEAK TO TIMING AND LONATION OVERNIGHT POPS. MORE WIDESPREAD SHOWERS BREAKING OUT ACROSS CENTRAL VA ARE IN RESPONSE TO THE SHORTWAVE JUST MOVING INTO THE REGION FROM THE NW. THE RAP IS HANDLING THIS FEATURE AND FORCING VERY WELL. EXPECT THE PRECIP TO CONTINUE TO EXPAND SOMEWHAT IN COVERAGE AND SPREAD EAST ACROSS CENTRAL VA AND THEN THE COAST INCLUDING MD...EASTERN SHORE AND SOUTHEAST VA. THUNDER ACTIVITY WITH THIS SHOULD BE LIMITED THOUGH CANNOT RULE OUT A FEW RUMBLES ESPECIALLY ACROSS NORTH CENTRAL VA...MD AND THE EASTERN SHORE. OVERALL TEMP FORECASTS REMAIN ON TRACK. PREVIOUS DISCUSSION... THE CURRENT SURFACE ANALYSIS INDICATES WEAK BROAD LOW PRESSURE IN VICINITY OF THE GREAT LAKES WITH A BOUNDARY EXTENDING SOUTHWARD FROM E-CENTRAL PA THROUGH THE WESTERN SHORE OF THE CHESAPEAKE BAY. THUNDERSTORMS HAVE DEVELOPED ALONG THE BOUNDARY OVER PA AHEAD OF A ~100KT UPPER JET DIVING ACROSS THE ERN GREAT LAKES. SPC MESOANALYSIS INDICATES 35-40KT OF EFFECTIVE SHEAR FROM SE PA THROUGH THE LOWER MD ERN SHORE ALONG WITH AN AXIS OF 1500J/KG OF MLCAPE. THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE OVER THE ERN SHORE LATER THIS AFTERNOON INTO THE EVENING HOURS AS THE JET DIVES SE. A FEW STRONGER STORMS ARE POSSIBLE BASED ON FAVORABLE DYNAMIC AND THERMODYNAMIC PARAMETERS...WITH THE PRIMARY THREAT BEING STRONG WIND GUSTS. THE MAIN LIMITING FACTOR WILL BE RATHER WEAK LAPSE RATES. OTHERWISE...A CHC (30-40%) OF GENERAL THUNDER IS EXPECTED OVERNIGHT AS THE UPPER JET ENERGY PASSES OVER THE AREA AND THE SURFACE BOUNDARY REMAINS IN PLACE. LESS FOG IS EXPECTED DUE TO THE PRESENCE OF MID/UPPER LEVEL CLOUD COVER. OVERNIGHT LOWS SHOULD RANGE FROM THE UPPER 60S TO LOW 70S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... MID/UPPER NW FLOW REMAINS OVER THE REGION FRIDAY INTO THE WEEKEND. A MORE VIGOROUS WAVE DROPS THROUGH THE FLOW ACROSS THE AREA FRIDAY NIGHT. THIS WILL PROVIDE BEST CHC OF AND GREATEST AREAL COVERAGE OF SHOWERS/TSTMS ACROSS THE LOCAL AREA DURING THE SHORT-TERM PERIOD DUE TO MORE FAVORABLE/STRONGER UPPER JET SUPPORT. POCKETS OF MODERATE TO HEAVY RAIN ARE POSSIBLE GIVEN MODEST MOISTURE AND FAVORABLE UPPER SUPPORT. HIGH PRESSURE BUILDS OVER NEW ENGLAND SATURDAY AND SLOWLY PUSHES INTO THE REGION BY SUNDAY. THIS WILL PUSH THE REMNANT FRONT S OF THE AREA. CHC POPS WILL CONTINUE EARLY SATURDAY...WITH A STEADY DRYING TREND COMMENCING SATURDAY AFTERNOON FROM NNE-SSW AS THE HIGH BUILDS INTO THE REGION. HIGHS FRIDAY SHOULD BE MAINLY 85-90...AND THEN FROM THE LOW TO MID 80S SATURDAY (UPPER 70S ALONG THE ATLANTIC BEACHES)...WITH UPPER 70S TO LOW 80S SUNDAY. LOWS SHOULD BE IN THE UPPER 60S TO LOW 70S SATURDAY...AND IN THE 60S SUNDAY MORNING. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... EXTENDED FORECAST PERIOD WILL CONSIST OF MAINLY NE FLOW AS HIGH PRESSURE TO THE NORTH RIDGES SOUTH WHILE AN AREA OF LOW PRESSURE EMERGES FROM THE BAHAMAS. THIS PATTERN WILL MAINTAIN A COOLER MARITIME AIRMASS IN PLACE OVER THE AREA THROUGH WED BEFORE HIGH PRESSURE AT THE SURFACE AND ALOFT BEGIN TO CENTER THEMSELVES OVER THE FA. AT THIS POINT SUBSIDENCE WILL PREVAIL AND WILL HELP TO DRY THE ATMOSPHERE. PRECIP ALONG THE VA/NC COAST CAN NOT BE COMPLETELY RULED OUT DUE TO THE INFLUX OF MOISTURE NORTH AS THE SURFACE LOW FORMS TO THE SOUTH. THERE IS SOME MODEL DISCREPANCY IN REGARDS TO THE POSITION AND STRENGTH OF THE LOW OVER THE TROPICAL ATLANTIC. AND DUE TO THE LARGE DEGREE OF CHANGE IN MODEL RUNS...AT THIS POINT... WILL NOT MODIFY THE PREVIOUS FORECAST TOO MUCH. TEMPS WILL REMAIN BELOW AVERAGE FOR MUCH OF THE EXTENDED PERIOD WITH HIGHS AROUND 80 MON AND TUES...WARMING SLIGHTLY INTO THE MID 80S WED AND THUR. SEASONAL LOW TEMPS IN THE LOW TO MID 60S ARE LIKELY AS THE MARITIME AIRMASS WILL LIMIT SIGNIFICANT OVERNIGHT COOLING. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... AS OF 23Z...A WARM FRONT EXTENDED FROM NEAR WASHINGTON DC THROUGH EASTERN VIRGINIA (BETWEEN RICHMOND AND HAMPTON ROADS) AND INTO EASTERN NORTH CAROLINA. WINDS WERE MAINLY FROM THE W/SW WEST OF THE BOUNDARY AND FROM THE E/SE TO THE EAST OF IT. THIS FRONT WILL MOVE TOWARD THE COAST OVERNIGHT. LOW PRESSURE MAY DEVELOP JUST OFF THE COAST FRIDAY WHICH WOULD HELP SHIFT THE WINDS BRIEFLY TO NW/N DURING THE DAY. WIDELY SCT TSTMS WERE OVER THE MID ATLANTIC STATES BUT NONE WERE A THEREAT TO THE TAF SITES. A BAND OF LIGHT RAIN MAY AFFECT SOME LOCATIONS LATER THIS EVENING. SBY HAS A T/TD SPREAD OF AROUND 5 DEGREES AND WITH RAIN HAVING FALLEN LATE THURSDAY...THERE MAY BE SOME MVFR/IFR FOG THERE. AN OVERCAST HIGH CEILING SHOULD LIMIT FOG FORMATION AT ALL LOCATIONS AND PRESENTLY NONE IS FORECAST AT THE OTHER TAF SITES. FRIDAY SHOULD BE A DRY AT THE BEGINNING BUT AN UPPER LEVEL SHORT WAVE MAY BRING A ROUND OF TSTMS LATE IN THE DAY OR FRIDAY NIGHT. OUTLOOK...THUNDERSTORM CHANCES CONTINUE INTO SATURDAY WITH DRY WEATHER FORECAST BEGINNING SUNDAY. MVFR/IFR DUE TO STRATUS OR FOG WILL BE A POTENTIAL A FEW HOURS AROUND SUNRISE THROUGH SUNDAY MORNING. && .MARINE... LOW PRESSURE FORMS ALONG A STATIONARY BOUNDARY THAT IS CURRENTLY POSITIONED OVER THE EASTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. THIS WEAK AREA OF LOW PRESSURE WILL MOVE OFF THE COAST FRIDAY AFTN. EARLY SAT MORNING...HIGH PRESSURE NOSES SOUTH FROM THE NORTHEASTERN US CAUSING A BACKDOOR COLD FRONT TO MOVE THROUGH THE AREA. ENERGY STREAMING SE WILL HELP FORM AN AREA OF LOW PRESSURE OFF THE CAROLINA COAST. THIS SYNOPTIC SETUP WILL ENHANCE THE PRESSURE GRADIENT ACROSS THE WATERS CAUSING NEAR SCA WIND GUST OVER THE BAY(18-20KT) AND THE COASTAL WATERS(23-25KT) ON SATURDAY. DUE TO THE WIND DIRECTION AND FETCH...EXPECT WAVES TO BUILD TO 4-6FT ACROSS MOST OF THE COASTAL WATERS LASTING EARLY SATURDAY THROUGH MONDAY NIGHT. HIGH PRESSURE BEGINS TO POSITION OVER THE AREA BY TUESDAY BUT LOW PRESSURE EMERGING FROM THE SOUTH MAY HELP TO MAINTAIN THE PRESSURE GRADIENT AND ONSHORE FLOW THROUGH WED. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT FRIDAY THROUGH FRIDAY EVENING FOR MDZ025. NC...NONE. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT FRIDAY THROUGH FRIDAY EVENING FOR VAZ099. MARINE...NONE. && $$ SYNOPSIS...AJZ/ALB NEAR TERM...AJZ/JAO SHORT TERM...AJZ/ALB LONG TERM...DAP AVIATION...LSA MARINE...DAP
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
256 PM EDT WED AUG 20 2014 .SYNOPSIS... A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THROUGH THURSDAY. THE BOUNDARY WILL SLOWLY DROP SOUTH AND WEST AS A COLD FRONT FRIDAY AND HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND INTO OUR AREA FOR THE WEEKEND. HOWEVER...UNSETTLED CONDITIONS MAY PERSIST DURING THIS TIME DUE TO PLENTY OF MOISTURE FROM THE ATLANTIC. && .NEAR TERM /THROUGH THURSDAY/... AN UPPER LEVEL TROUGH IS LOCATED ACROSS THE GREAT LAKES WHILE MULTIPLE DISTURBANCES MOVE ACROSS THE MID WEST IN NORTHWEST FLOW ALOFT. A JET STREAK IS ROUNDING THE BASE OF THE TROUGH ACROSS THE GREAT LAKES AND OHIO VALLEY. A WEAKENING SHORTWAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE ALLEGHENY FRONT THIS AFTERNOON WHILE SHOWERS AND THUNDERSTORMS MOVE EASTWARD ACROSS THE POTOMAC HIGHLANDS...SHENANDOAH VALLEY AND NORTHERN VA. MESOSCALE ANALYSIS SHOWS 500-1000 J/KG WEST OF I-95 AND 25-30KTS OF SHEAR. PWATS HAVE RISEN TO 1.6-1.8 INCHES ACROSS THIS REGION. AN ISOLATED SEVERE THREAT WILL CONTINUE THIS AFTERNOON WITH DMG WINDS AS THE MAIN THREAT. BOWING SEGMENTS AND RIJ SIGNITURES HAVE BEEN OBSERVED ON RADAR. AT THIS TIME...HAVE NOT CONFIRMED GROUND TRUTH REPORTS FOR DMG WINDS. HEAVY RAINFALL HAS ALSO BEEN OBSERVED. HRRR INCREASES COVERAGE OF SHOWERS AND THUNDERSTORMS AND ACTIVITY SHOULD REACH THE I-95 LATE THIS AFTERNOON AND EARLY EVENING. SHOWERS AND THUNDERSTORMS WILL DECREASE IN COVERAGE THIS EVENING. SOUTHERLY FLOW AT THE SFC WILL KEEP MOIST CONDITIONS ACROSS THE MID ATLANTIC. PATCHY FOG IS POSSIBLE ACROSS THE REGION MAINLY IN VALLEY LOCATIONS AND LOCATIONS THAT RECEIVED RAIN TODAY. THE UPPER LEVEL TROUGH WILL MOVE ACROSS ONTARIO BY THURSDAY MORNING AS A RIDGE BUILDS INTO THE CENTRAL PLAINS. MULTIPLE DISTURBANCES ARE EXPECTED TO MOVE ACROSS THE MID WEST BUT TIMING IS DIFFICULT. A SFC TROUGH IS EXPECTED ACROSS THE REGION THURSDAY. THIS WILL PRODUCE WESTERLY WINDS BEHIND THE TROUGH AND SOUTHERLY FLOW AHEAD OF THE TROUGH. AT THIS TIME...A DISTURBANCE IS EXPECTED TO APPROACH THE REGION THURS AFTERNOON FROM THE NORTHWEST. SHOWERS AND THUNDERSTORMS WILL MOVE INTO THE REGION AT THIS TIME AND MOVE EAST-SOUTHEAST. THE SFC TROUGH WILL ALSO LEAD TO ISOLATED DEVELOPMENT IN THE AFTERNOON. AT THIS TIME...INSTABILITY WILL BE MARGINAL AND SHEAR SEEMS WEAK. ACTIVITY SHOULD BE SUB-SEVERE. PWATS ARE EXPECTED TO RISE NEAR 1.9 INCHES THURSDAY PRODUCING HUMID CONDITIONS. SHOWERS AND THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY RAIN. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THURSDAY NIGHT AND INTO FRIDAY AS A 250MB JET SITS NEAR THE REGION AND DISTURBANCES APPROACH FROM THE GREAT LAKES. SUBSIDENCE BEHIND THE DEPARTING DISTURBANCES MAY LEAD TO CLEARING FRIDAY AND THEREFORE INSTABILITY WILL LIKELY INCREASE. AT THIS TIME...CONFIDENCE IS LOW ON THE TIMING OF SHOWERS AND THUNDERSTORMS. FCST MAX TEMPS WILL REACH THE LOW 80S ON FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A WEAK WAVE OF LOW PRESSURE FOCUSED IN THE MID AND UPPER LEVELS WILL CROSS THE AREA OVERNIGHT FRIDAY...PROVIDING ONE FINAL PERIOD OF ENHANCED RAINFALL AS A BACKDOOR COLD FRONT MOVES THROUGH AT THE SURFACE. A SUBTROPICAL RIDGE WILL BUILD OVER THE EASTERN US FOR WEEKEND AS SURFACE HIGH PRESSURE CENTERED OVER THE NORTHEASTERN US RIDGES DOWN THE EASTERN SEABOARD. THIS RIDGING COMBINED WITH EASTERLY FLOW AROUND THE NORTH SIDE OF A COASTAL LOW OFF OF CAPE HATTERAS WILL BRING ONSHORE FLOW FOR THE MID-ATLANTIC MIDDAY SATURDAY THROUGH THE BEGINNING OF NEXT WORKWEEK. THE MARINE LAYER THAT WILL FILL IN WILL BRING SEASONABLY COOL AND MOIST AIR...LEADING TO A LOW CLOUD DECK THAT WILL HANG AROUND THROUGH THE WEEKEND AND LIKELY INTO MONDAY EVENING...PARTICULARLY EAST OF THE BLUE RIDGE. CHANCE POPS WILL REMAIN IN THE FORECAST ALONG AND WEST OF THE BLUE RIDGE WHERE THERE WILL BE AN UPSLOPE COMPONENT TO THE MOIST EASTERLY FLOW. THE SURFACE HIGH WILL MIGRATE OFF OF THE MID-ATLANTIC COAST MONDAY NIGHT AND SOUTHERLY FLOW WILL BEGIN TO FILL IN LOCALLY. THIS WILL SIGNAL AN INCREASE IN TEMPERATURES AS HIGHS WILL GO FROM THE MID TO UPPER 70S SATURDAY THROUGH MONDAY TO NEAR 80 TUESDAY AND MID 80S WEDNESDAY. NO SIGNIFICANT PRECIPITATION FEATURES ARE EXPECTED THROUGH THE FIRST HALF OF NEXT WEEK. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... SHRA AND TSRA IS EXPECTED THIS AFTERNOON AS A LINE OF TSRA MOVES EASTWARD. GUSTY WINDS AND IFR VSBYS POSSIBLE IN TSRA. THIS WILL CONTINUE THIS AFTERNOON. SOUTHERLY FLOW WILL KEEP MOISTURE IN THE REGION OVERNIGHT AND PATCHY IFR VSBYS ARE POSSIBLE AT MRB AND CHO. MVFR VSBYS ARE POSSIBLE AT IAD. MVFR/IFR CIGS ARE POSSIBLE NEAR BWI-MTN BUT CONFIDENCE IS LOW AT THIS TIME. SHRA AND TSRA POSSIBLE THURSDAY AFTERNOON AND INTO FRIDAY AND MAY CAUSE MVFR/IFR RESTRICTIONS. PERIODS OF LOW CEILINGS ARE POSSIBLE AS A MID AND UPPER LEVEL DISTURBANCE CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA. && .MARINE... SOUTHERLY FLOW WILL CONTINUE ON THE WATERS THROUGH FRIDAY. WINDS SHOULD STAY BELOW SCA CRITERIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING AND AGAIN THURSDAY AFTERNOON AND NIGHT. SOME THUNDERSTORMS MAY PRODUCE GUSTY WINDS. A SMALL CRAFT ADVISORY MAY BE NECESSARY SATURDAY NIGHT THROUGH SUNDAY NIGHT IN BREEZY EASTERLY FLOW AROUND THE NORTH SIDE OF A COASTAL LOW OFF OF THE NORTH CAROLINA FLOW. && .TIDES/COASTAL FLOODING... AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN WEAK. THE FLOW MAY TURN MORE TOWARD THE SOUTHEAST WHICH WOULD CAUSE WATER LEVELS TO BE SLIGHTLY HIGHER THAN THEY HAVE BEEN RECENTLY. THIS WILL CAUSE WATER LEVELS TO BE CLOSE TO MINOR FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY THURSDAY MORNING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...HAS LONG TERM...CEB AVIATION...HAS/CEB MARINE...HAS/CEB TIDES/COASTAL FLOODING...LWX
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
930 AM EDT WED AUG 20 2014 .SYNOPSIS... A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION THROUGH THURSDAY. THE BOUNDARY WILL SLOWLY DROP SOUTH AND WEST AS A COLD FRONT FRIDAY AND HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND INTO OUR AREA FOR THE WEEKEND. HOWEVER...UNSETTLED CONDITIONS MAY PERSIST DURING THIS TIME DUE TO PLENTY OF MOISTURE FROM THE ATLANTIC. && .NEAR TERM /THROUGH TONIGHT/... A SHORTWAVE TROUGH WILL APPROACH THE MID ATLANTIC THIS MORNING. SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING ACROSS THE OHIO VALLEY AND APPALACHIAN MTNS AND WILL BE MOVING ACROSS THE ALLEGHENY FRONT THIS MORNING. VISIBLE SATELLITE SHOWS MOSTLY SUNNY CONDITIONS WEST OF THE BLUE RIDGE. FURTHER EAST...S-SE WINDS HAVE BANKED CLOUDS AGAINST THE BLUE RIDGE MTNS SOUTH OF THE POTOMAC RIVER RESULTING IN LOW CLOUDS FOR LOCATIONS ADJACENT TO THE MTNS THIS MORNING. THESE CLOUDS MAY CREEP NORTHWARD BEFORE DISSIPATING THIS AFTERNOON. 12Z IAD RAOB HAS ABOUT 500 J/KG OF SBCAPE AND AFTER MODIFYING IT FOR THE AFTERNOON...INSTABILITY IS EXPECTED TO INCREASE TO AROUND 1000 J/KG. INSTABILITY SHOULD INCREASE MORE IF AN AREA RECEIVES MORE HEATING. DEWPTS ARE EXPECTED TO STAY OR REACH THE UPPER 60S TO AROUND 70 BY THE AFTERNOON AND AS MOISTURE MOVES IN FROM THE WEST...PWATS WILL LIKELY INCREASE TO AROUND 1.8 INCHES. SHEAR IS WEAK...AROUND 25KTS AND THUNDERSTORMS SHOULD STAY SUB-SEVERE TODAY. HRRR HAS LINE OF SHOWERS AND THUNDERSTORMS MOVING EASTWARD THROUGH THE MORNING AND REACHING THE BLUE RIDGE BY EARLY AFTERNOON AND THE I-95 CORRIDOR LATE THIS AFTERNOON. ACTIVITY IS MORE ISO-SCT FURTHER SOUTH AND THE BEST CHANCE FOR RAIN WILL BE NORTH OF I-66 AS SHORTWAVE ENERGY MOVES TO THE NORTH. MAIN THREAT IN ACTIVITY WILL BE HEAVY RAIN IN SHOWERS AND THUNDERSTORMS. PREVIOUS DISCUSSION... MAX TEMPS WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MIDDLE 80S ACROSS MOST OTHER LOCATIONS. COVERAGE IN CONVECTION SHOULD DIMINISH OVERNIGHT...BUT WITH THE BOUNDARY NEARBY AND SHORTWAVE ENERGY MOVING THROUGH...A FEW SHOWERS CANNOT BE RULED OUT. AREAS OF LOW CLOUDS AND FOG WILL DEVELOP LATE TONIGHT AS WELL. WARM AND HUMID CONDITIONS WILL PERSIST WITH MIN TEMPS RANGING FROM NEAR 60 IN THE ALLEGHENY HIGHLANDS TO THE LOWER 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... THE UPPER-LEVEL LOW WILL MOVE INTO NEW ENGLAND THURSDAY THROUGH THURSDAY NIGHT. SHORTWAVE ENERGY WILL CONTINUE TO ROTATE THROUGH THE AREA IN A NORTHWEST FLOW ALOFT. THE BOUNDARY WILL REMAIN NEARLY STATIONARY FROM CENTRAL MARYLAND THROUGH CENTRAL VIRGINIA AND THE WARM AND HUMID AIRMASS WILL REMAIN OVERHEAD. MORE SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH COVERAGE BEING SCATTERED TO NUMEROUS...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. MAX TEMPS THURSDAY WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE MID AND UPPER 80S ACROSS MOST OTHER LOCATIONS. MIN TEMPS THURSDAY NIGHT WILL RANGE FROM THE LOWER 60S IN THE ALLEGHENY HIGHLANDS TO THE LOWER 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. PATCHY LOW CLOUDS AND FOG ARE EXPECTED OVERNIGHT AS MOISTURE GETS TRAPPED UNDERNEATH THE NOCTURNAL INVERSION. && .LONG TERM /FRIDAY THROUGH TUESDAY/... H5 PTTN MUCH MORE AMPLIFIED/ACTIVE THAN NORMAL FOR LT AUG...BUT THEN AGAIN THIS HASNT BEEN A TYPICAL SUMMER. A SUBTROPICAL RDG WL BE ANCHORED OVER THE MS VLY THRU MUCH OF THE PD. THAT LEAVES CWFA IN NW FLOW ALOFT...AND TEMPS COOLER THAN CLIMO. WUD LOVE TO BE AS DEFINITIVE W/ POPS. HWVR...SUBSIDENCE WL BE CONFINED TO OVER NEW ENGLAND. WHILE AMS LKLY WONT BE OUTRIGHT CAPPED...THERE ARENT SPECIFIC DISCERNABLE FORCING MECHANISMS EITHER...BUT THERE WL BE THE JETSTREAM ABV AREA AT HIER LVLS. THAT LEAVES SENSIBLE WX SUSCEPTIBLE TO MID-UPA DYNAMICS SUCH AS S/WV IMPULSES EMBEDDED W/IN MEAN LYR FLOW. IT APPEARS AS THOUGH THERE WL BE SUCH A DISTURBANCE FRI NGT INTO SAT. INSTBY MEAGER...AND BECOME INCREASINGLY LMTD AS SFC FLOW BECOMES ELY. BYD THAT...EVEN BROAD DETAILS BECOME PROBLEMATIC. BY ELY NXT WK... RDGG SHUD RETROGRADE...PROVIDING A BETTER BET AT SOME DRY CONDS IN THE CSTL PLAIN. STILL CANT RULE OUT A SHRA IN THE MTNS...BUT THE CHCS FAR LESS. && .AVIATION /13Z WEDNESDAY THROUGH SUNDAY/... MVFR CONDITIONS WILL CONTINUE AT CHO THIS MORNING. SCT MVFR CONDITIONS ARE LIKELY AT IAD-DCA AS LOW CLOUDS CONTINUE TO MOVE NORTHWARD AGAINST THE MTNS. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING. MORE LOW CLOUDS AND FOG WILL DEVELOP LATE TONIGHT INTO THURSDAY MORNING. SHOWERS AND THUNDERSTORMS ARE POSSIBLE THURSDAY AND THURSDAY NIGHT...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. FLGT RESTRICTIONS PROBABLE W/IN SHRA/TSRA THRU THE WKND. HWVR... AREAL CVRG A WILD CARD. FRI NGT-SAT LOOK TO BE THE WETTEST PART OF THE OUTLOOK ATTM. && .MARINE... A BOUNDARY WILL REMAIN NEAR THE WATERS THROUGH THURSDAY NIGHT...BUT THE PRESSURE GRADIENT SHOULD BE WEAK ENOUGH TO PREVENT SCA CRITERIA WINDS DURING THIS TIME. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE...ESPECIALLY LATE THIS AFTERNOON THROUGH THIS EVENING...AND AGAIN THURSDAY AFTERNOON AND THURSDAY NIGHT. ATTM NO ADVYS XPCTD THRU THIS WKND. HWVR UNSTTLD CONDS WL PREVAIL... AND CANNOT PRECLUDE A FEW MARINE WRNGS INVOF TSRA. && .TIDES/COASTAL FLOODING... AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN WEAK. THE FLOW MAY TURN MORE TOWARD THE SOUTHEAST WHICH WOULD CAUSE WATER LEVELS TO BE SLIGHTLY HIGHER THAN THEY HAVE BEEN RECENTLY. THIS WILL CAUSE WATER LEVELS TO BE CLOSE TO MINOR FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY THURSDAY MORNING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...BJL/HAS SHORT TERM...BJL LONG TERM...HTS AVIATION...BJL/HAS/HTS MARINE...BJL/HAS/HTS TIDES/COASTAL FLOODING...BJL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
133 AM EDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 422 PM EDT TUE AUG 19 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW FROM WRN LAKE SUPERIOR INTO W UPPER MI. A SHORTWAVE NEAR THE LOW CENTER SUPPORTED AN AREA OF SHOWERS...SOME LOCALLY HEAVY...THROUGH CNTRL UPPER MI. WITH THE SLOW FORWARD MOVEMENT...PWAT AROUND 1.5 INCHES...AND EFFICIENT WARM RAIN PROCESSES...NEARLY 2.0 INCHES OF RAIN FELL AT THE NWS OFFICE BTWN 1915Z-1945Z. AN FLS WAS ISSUED TO HIGHLIGHT THREAT FOR MINOR FLOODING WITH SMALL STREAMS AND LOW-LYING AREAS. AT THE SFC...LOW PRES WAS LOCATED OVER NW UPPER MI. EXPECT THE VERTICALLY STACKED LOW TO ONLY SLOWLY WOBBLE TO THE EAST TO CNTRL/EAST UPPER MI BY 12Z/WED AND TO NEAR THE STRAITS BY 00Z/THU. THERE WILL BE A CONTINUED THREAT FOR SOME LOCALLY HEAVY RAIN WITH THE SHRTWV MOVING THROUGH CNTRL UPPER MI THIS EVENING. ONLY ISOLD TSRA ARE EXPECTED...GIVEN AFTERNOON TRENDS AND MUCAPE BLO 1K J/KG. OTHERWISE...HIGH RES MODELS AND UPSTREAM RADAR TRENDS SUGGEST RAIN WILL BECOME MORE SCATTERED THIS EVENING AND DIMINISH FURTHER OVERNIGHT. WITH ABUNDANT DEEP MOISTURE REMAINING OVER THE REGION THROUGH WED MORNING...SOME SCT LIGHT SHOWERS OR DRIZZLE WILL REMAIN POSSIBLE THROUGH THE MORNING...ESPECIALLY OVER THE N CNTRL AND EAST EVEN WITH WEAK FORCING NEAR THE LOW. HOWEVER...ANY ADDITIONAL RAINFALL AMOUNTS SHOULD BE LIGHT...LESS THAN A TENTH OF AN INCH. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 402 PM EDT TUE AUG 19 2014 THE UPPER LEVEL WAVE AND ASSOCIATED WEAK LOW PRESSURE SYSTEM THAT ARE CURRENTLY OVER THE AREA WILL CONTINUE TO INFLUENCE THE UPPER GREAT LAKES REGION INTO WEDNESDAY BEFORE PULLING OUT ON WEDNESDAY NIGHT. AS THIS WAVE PULLS OUT...SHOULD SEE A DRY PERIOD OVER MUCH OF THE U.P. FOR WEDNESDAY NIGHT INTO THURSDAY MORNING (ALTHOUGH THERE COULD BE SOME LINGERING SHOWERS OVER THE NORTHEAST ON WEDNESDAY EVENING) BEFORE THE NEXT WAVE ARRIVES THURSDAY AFTERNOON AND REMAINS INTO FRIDAY. THE DRY PERIOD WILL BE AIDED BY THE WEAK RIDGING ALOFT THAT WILL MOVE INTO THE UPPER GREAT LAKES REGION AND ATTEMPT TO BUILD INTO THE GREAT LAKES REGION THROUGH THE WEEKEND. AS THAT RIDGING OCCURS...AN UPPER TROUGH WILL ESTABLISH ITSELF OVER THE NORTHERN ROCKIES AND EJECT OUT A COUPLE PIECES OF ENERGY THROUGH THE REST OF THE EXTENDED PERIOD. THE FIRST WAVE WILL MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY AND THEN SHIFT NORTHEAST ACROSS THE MINNESOTA ARROWHEAD THURSDAY EVENING AND INTO ONTARIO ON FRIDAY. THERE ARE STILL SOME MODEL DIFFERENCES WITH HOW PROGRESSIVE THIS SHORTWAVE AND ASSOCIATED WEAK LOW (AND WARM FRONT) ARE...AND IT IS LARGELY TIED INTO THE STRENGTH OF THE SHORTWAVE. AT THIS POINT...THE 12Z GFS APPEARS TO BE THE OUTLIER (KEEPS THE WARM FRONT SOUTH OF THE CWA DUE TO WEAKER SHORTWAVE UNTIL THE NEXT WAVE ARRIVES ON SATURDAY) WHILE THE 00Z ECMWF AND ITS ENSEMBLE MEMBERS...ALONG WITH THE 12Z GEM/NAM...BRING THE WARM FRONT INTO THE AREA LATE THURSDAY AFTERNOON AND PUSHING NORTHEAST OF THE AREA ON FRIDAY NIGHT INTO SATURDAY. THINK THE NON GFS CONSENSUS IS THE WAY TO GO AT THIS POINT AND FOLLOWS THE GENERAL IDEA FROM THE PREVIOUS SHIFT. THEREFORE...WILL INCREASE PRECIP CHANCES FROM SOUTHWEST TO NORTHEAST THURSDAY AFTERNOON INTO THURSDAY NIGHT AND THEN KEEP CHANCE POPS INTO THE FIRST PART OF THE WEEKEND. WILL NEED TO KEEP AN EYE ON CONVECTION FIRING IN EAST CENTRAL MINNESOTA AND NORTHWEST WISCONSIN THURSDAY AFTERNOON ALONG THE WARM FRONT AND LOW LEVEL MOISTURE TRANSPORT MAXIMUM IS LOCATED. COULD SEE SOME STRONG TO POTENTIAL SEVERE STORMS IN THAT AREA...WHICH BASED OFF STORM MOTION VECTORS WOULD TRY TO LIFT THEM EAST-NORTHEAST ALONG WITH THE FRONT WHILE BUILDING TO THE SOUTHEAST. FAR WESTERN UPPER MICHIGAN WOULD HAVE THE BEST OPPORTUNITY FOR SEEING THESE STRONGER STORMS HEADING INTO THE EVENING HOURS. ONCE THAT WAVE DECAYS AND SLIDES NORTHEAST OF THE CWA...PRECIPITATION CHANCES WILL DEPEND ON OTHER WAVES EJECTING OUT OF THE UPPER TROUGH OVER THE NORTHERN ROCKIES. RIDGE AXIS WILL BE RIGHT OVER THE U.P. THROUGH SUNDAY AND THEN SHIFT EAST FOR THE BEGINNING OF NEXT WEEK AS THE UPPER TROUGH GRADUALLY SHIFTS EAST. WITH THAT RIDGE AXIS...IT APPEARS THAT SUNDAY WILL BE THE BEST OPPORTUNITY FOR DRIER WEATHER BEFORE THE NEXT WAVE SLIDES NORTHEAST OVER THE WESTERN HALF OF THE CWA SUNDAY NIGHT INTO MONDAY MORNING. EXPECT IT TO BE FAIRLY MUGGY OVER THE AREA FRIDAY INTO THE WEEKEND....ESPECIALLY WHEN COMPARED TO WHAT HAS BEEN SEEN IN THIS REGION FOR MUCH OF THE SUMMER. AFTER THE NORMAL TO SLIGHTLY ABOVE NORMAL TEMPERATURES VALUES THURSDAY THROUGH SUNDAY...THEY ARE EXPECTED TO FALL BACK BELOW NORMAL FOR MONDAY AND TUESDAY BEHIND THE COLD FRONT ASSOCIATED WITH THE WAVE THAT MOVES THROUGH ON SUNDAY NIGHT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 133 AM EDT WED AUG 20 2014 LOW PRES SYSTEM OVER THE UPPER GREAT LAKES WILL VERY SLOWLY DRIFT ESE OVER THE NEXT 24HRS. ABUNDANT LOW-LEVEL MOISTURE ASSOCIATED WITH SYSTEM WILL RESULT IN LIFR TO POSSIBLY OCNL VLIFR CONDITIONS AT KIWD/KCMX/KSAW THRU AT LEAST MID MORNING. -SHRA/-DZ MAY ALSO OCCUR AT TIMES...ESPECIALLY AT KCMX. GRADUAL IMPROVEMENT SHOULD OCCUR THIS AFTN...THOUGH ONLY KIWD SHOULD REACH VFR BY THE LATTER PART OF THE AFTN. KCMX/KSAW MAY NOT GET ABOVE THE LOW MVFR RANGE. AFTER SUNSET...CONDITIONS MAY AGAIN FALL AT KCMX/KSAW...BUT ESPECIALLY AT KSAW WHICH WILL BE CLOSER TO DEPARTING SYSTEM. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 422 PM EDT TUE AUG 19 2014 SOME FOG IS EXPECTED TO PERSIST OVER THE CNTRL AND ERN LAKE TONIGHT GIVEN ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS. EXPECT WINDS UNDER 20 KTS THROUGH SATURDAY AS A RELATIVELY WEAK PRESSURE GRADIENT DOMINATES THE UPPER GREAT LAKES ABOVE THE RELATIVELY COLD WATERS OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
715 PM CDT THU AUG 21 2014 .UPDATE... ISSUED AT 700 PM CDT THU AUG 21 2014 THE 18Z NAM HAS FAILED TO CAPTURE THE ONGOING CONVECTION ACROSS OUR SOUTHEASTERN FORECAST AREA AND IS ESSENTIALLY DRY THROUGH MIDNIGHT. HOWEVER...THE HRRR MODEL SEEMS TO BE CATCHING ONTO THINGS AND HAS BEEN GIVING FAIRLY REALISTIC SCENARIOS FOR HOW THUNDERSTORMS WILL EVOLVE THIS EVENING. BASED ON RADAR AND THE HRRR HAVE INCREASED POPS INTO THE LIKELY CATEGORY FOR MOST OF OUR KANSAS COUNTIES INTO NUCKOLLS...THAYER...AND FILLMORE COUNTIES. ALSO SLIGHTLY INCREASED POPS NORTH OF THE RADAR FINE LINE BOUNDARY THAT AT 7 PM WAS RUNNING FROM PHILLIPSBURG...TO BLUE HILL. THE LOW LEVEL JET WILL INCREASE THIS EVENING WITH THE NOSE OF THE JET RUNNING INTO OUR SOUTHERN FORECAST AREA. THE HRRR INDICATES THAT THUNDERSTORMS COULD FORM NORTH OF THE EXISTING THUNDERSTORMS LATER THIS EVENING IN PLACES LIKE HASTINGS AS THE LOW LEVEL JET INCREASES...BUT CONFIDENCE IN THIS IS STILL LESS THAN 50 PERCENT. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 341 PM CDT THU AUG 21 2014 MAP ANALYSIS INDICATES AN UPPER TROPOSPHERIC RIDGE OVER THE CENTRAL CONUS...WITH TROUGHS OVER THE WESTERN AND EASTERN CONUS. MAP ANALYSIS ALSO SHOWS A CLOSED UPPER TROPOSPHERIC LOW EMBEDDED WITHIN THE BASE OF THE WESTERN CONUS TROUGH. ENHANCED UPPER TROPOSPHERIC ENERGY EXTENDS FROM NORTH TO SOUTH ALONG THE WESTERN CONUS COAST...THEN NORTHEAST INTO THE NORTHERN PLAINS...AND FINALLY BACK TO THE SOUTHEAST ACROSS THE GREAT LAKES REGION. THAT BEING SAID...UPPER TROPOSPHERIC FLOW OVER OUR AREA REMAINS FAIRLY WEAK...ONLY MAXING OUT AT AROUND 35KTS NEAR 38000FT AGL PER RAP ANALYSIS DATA AT 12Z. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED RIDGE AND TROUGHS...AS WELL AS ENHANCED UPPER TROPOSPHERIC MOISTURE EXTENDING FROM HURRICANE LOWELL INTO THE SOUTHWESTERN CONUS. THIS TROPICAL MOISTURE HAS YET TO REACH THE CENTRAL PLAINS HOWEVER. AT THE SURFACE AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER SOUTHWESTERN MINNESOTA...AND AN ASSOCIATED SURFACE TROUGH EXTENDS SOUTHWEST FROM THE LOW INTO NEBRASKA AND KANSAS. AS OF 18Z THIS TROUGH WAS NOTED EXTENDING FROM NEAR KODX...TO NEAR KHDE...TO NEAR KHLC. THE RESULTANT LOWER TROPOSPHERIC WIND FIELD ACROSS OUR AREA REMAINS FROM THE SOUTH ACROSS EASTERN PORTIONS OF OUR CWA...BUT LOCATIONS FARTHER WEST/NORTHWEST...BEHIND THE TROUGH...ARE NOW REPORTING A NORTHERLY COMPONENT TO THE LOWER TROPOSPHERIC WIND FIELD. GUIDANCE SUGGESTS THE CLOSED UPPER TROPOSPHERIC LOW OVER THE WESTERN CONUS WILL EJECT FROM THE BASE OF THE LONG WAVE TROUGH AS A SHORT WAVE TONIGHT INTO FRIDAY...LIKELY MOVING INTO THE FOUR CORNERS REGION BY 00Z SATURDAY. AS A RESULT...SURFACE CYCLOGENESIS THEN EXPECTED OVER WESTERN KANSAS FRIDAY AFTERNOON. SO ALTHOUGH THE SURFACE TROUGH...CURRENTLY LOCATED OVER OUR AREA...WILL MAKE AN ATTEMPT TO MOVE EAST ACROSS THE AREA TONIGHT...THE TROUGH SHOULD EVENTUALLY BECOME STATIONARY IF NOT RETROGRADE SOMEWHAT AS IT STRENGTHENS INTO A WARM FRONT IN RESPONSE TO THE WESTERN KANSAS CYCLOGENESIS. THE LOWER TROPOSPHERIC WIND FIELD ACROSS THE SOUTH/SOUTHEASTERN ONE-HALF OF THE CWA WILL LIKELY REMAIN FROM THE SOUTH/SOUTHEAST THROUGH THE NEXT 24 HOURS...BUT LOCATIONS FARTHER NORTHWEST WILL LIKELY EXPERIENCE MORE OF A NORTHEASTERLY WIND FIELD. ANY OMEGA DERIVED FROM UPPER TROPOSPHERIC KINEMATICS SHOULD REMAIN ON THE WEAK SIDE THROUGH MUCH OF THE SHORT TERM FORECAST PERIOD. THAT BEING SAID...GUIDANCE DOES SUGGEST THE AXIS OF A ~50KT LOWER TROPOSPHERIC JET STREAK JUST ABOVE THE BOUNDARY LAYER WILL DEVELOP FROM CENTRAL KANSAS INTO SOUTHEASTERN NEBRASKA TONIGHT...BEFORE SHIFTING OFF TO THE EAST SOMEWHAT BY DAYBREAK FRIDAY. THERMAL ADVECTION ALONG THIS AXIS...AS WELL AS MOISTURE CONVERGENCE NEAR THE NOSE OF THE JET STREAK...SHOULD BE SUFFICIENT FOR PRECIPITATION PRODUCTION...ESPECIALLY ACROSS OUR SOUTHEASTERN CWA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS AND EC...AS WELL AS SIMULATED REFLECTIVITY FROM THE HRRR. GIVEN ALL THIS...WENT AHEAD WITH 20-30% POPS ACROSS MUCH OF THE CWA FOR TONIGHT...WITH THE HIGHEST POPS RELEGATED TO THE SOUTHEASTERN CWA. ANY PRECIPITATION THAT DOES DEVELOP TONIGHT SHOULD MOVE OFF TO THE EAST BY SUNRISE FRIDAY AS THE AXIS OF THE LOWER TROPOSPHERIC JET STREAK DOES THE SAME. THIS SHOULD PROVIDE A BREAK IN THE PRECIPITATION ACROSS OUR AREA FRIDAY MORNING INTO LATE FRIDAY AFTERNOON. BY LATE FRIDAY AFTERNOON AND INTO FRIDAY EVENING HOWEVER...THERMAL ADVECTION AHEAD OF THE APPROACHING UPPER TROPOSPHERIC SHORT WAVE SHOULD PROMOTE INCREASING OMEGA ACROSS THE REGION. THIS OMEGA...WORKING IN CONCERT WITH ENHANCED LOWER TROPOSPHERIC CONVERGENCE ALONG THE STRENGTHENING BAROCLINIC ZONE...MAY BE SUFFICIENT FOR THE DEVELOPMENT OF ISOLATED TO PERHAPS SCATTERED SHOWER AND THUNDERSTORM ACTIVITY. THIS IS A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS AND EC. GIVEN ALL THIS..WENT AHEAD WITH 20-50% POPS ACROSS THE CWA FRIDAY AFTERNOON AND EVENING...WITH THE HIGHEST POPS RELEGATED TO CENTRAL AND NORTHERN PORTIONS OF THE CWA IN CLOSEST PROXIMITY TO THE LOWER TROPOSPHERIC BAROCLINIC ZONE. FORECAST PROXIMITY SOUNDINGS FROM THE ACROSS THE CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST PARCELS ROOTED TO AROUND 800MB SHOULD HAVE 500-1000J/KG WITH ANY CONVECTION THAT IS REALIZED TONIGHT. GIVEN THIS...WILL GO AHEAD AND OUTLOOK THE POSSIBILITY FOR LARGE HAIL AND STRONG WIND GUSTS IN THE HWO FOR TONIGHT. TURNING TO FRIDAY AFTERNOON AND EVENING...THE NAM...OPERATIONAL GFS AND EC SUGGEST 0-1KM MLCAPE VALUES OF 1000-3000J/KG WILL BE IN EXISTENCE WITH DEEP-LAYER BULK SHEAR VALUES OF 15-30KTS. GIVEN THIS...SEVERE WEATHER IS A DEFINITE POSSIBILITY WITH ANY THUNDERSTORM THAT DOES DEVELOP AND AS A RESULT...WILL GO AHEAD AND OUTLOOK LARGE HAIL AND STRONG WIND IN THE HWO FOR LATE FRIDAY AFTERNOON AND FRIDAY EVENING. ALSO...LOCALLY ENHANCED LOWER TROPOSPHERIC HORIZONTAL VORTICITY ALONG THE AXIS OF THE BAROCLINIC ZONE COULD PROMOTE A THREAT FOR ISOLATED TORNADOES WITH ANY STORM THAT CAN LATCH ONTO THE BOUNDARY. GIVEN THIS...WILL ALSO OUTLOOK THE THREAT FOR ISOLATED TORNADIC ACTIVITY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 341 PM CDT THU AUG 21 2014 FRIDAY EVENING THROUGH THURSDAY. FORECAST CONCERN IN THE EXTENDED CENTERS ON CONTINUING RAIN CHANCES ALONG WITH SLIGHT COOLING TREND. BEGINNING FRIDAY EVENING...MODELS CONSISTENT WITH BIG PICTURE AS THEY HAVE AN UPPER LEVEL RIDGE OVER THE MISSISSIPPI RIVER VALLEY AND A LOW CENTERED OVER NORTH CENTRAL IDAHO. THE LOW OVER SOUTHERN CALIFORNIA AT PRESENT IS FORECAST TO EJECT OUT AHEAD OF THE MAIN PACIFIC NW CLOSED LOW AS A SHORTWAVE TROUGH AND SHOULD MOVE NORTHEAST AFFECTING THE CENTRAL PLAINS LATE FRIDAY EVENING. IT SHOULD HELP LIFT A SURFACE LOW AND ASSOCIATED WARM FRONT NORTH THROUGH NEB OVERNIGHT. THE NAM AND GFS STILL DIFFER SOME ON THE LOCATION BUT ARE SIMILAR IN LIFTING THE PRECIPITATION FROM OUR CWA INTO NORTHERN NEB OVERNIGHT. HEAVY RAIN IS POSSIBLE AS THE SYSTEM MOVES SLOWLY NORTH WITH PLENTY OF MOISTURE AVAILABLE. THE KS PORTION OF OUR CWA MAY REMAIN CAPPED AND MISS OUT ON THE ACTION...DEPENDING WHERE THE THUNDERSTORMS FIRST FIRE UP. ML-CAPE AND DEEP LAYER SHEAR APPEAR HIGH ENOUGH FOR SEVERE STORMS INTO THE EVENING...ALTHOUGH BETTER SHEAR PROGGED TO BE IN THE WESTERN PART OF NEB AS OF NOW. DECENT LOW LEVEL JET OF 30-40 KT ALSO FORECAST TO DEVELOP AND RIDE OVER WARM FRONT WHICH SHOULD HELP SUSTAIN STORMS. PLAN TO TRIM POPS FROM SOUTH TO NORTH OVERNIGHT. RAIN CHANCES SHOULD CONTINUE FOR THE WEEKEND WITH THE BEST TIME FRAME FOR RAIN BEING LATE AFTERNOON INTO THE NIGHT. THE UPPER TROUGH IS EXPECTED TO MOVE A BIT EASTWARD PUTTING US IN SOUTHWEST FLOW. MEANWHILE A COLD FRONT SHOULD STALL OUT AS IS BECOMES PARALLEL TO THE UPPER FLOW AND SHOULD BE SITUATED FROM THE EASTERN DAKOTAS TO SOUTHWEST KANSAS. RAIN CHANCES WILL DEPEND ON SEVERAL FACTORS INCLUDING FRONTAL CONVERGENCE...LOW LEVEL JET DEVELOPMENT...SHORTWAVE TROUGHS MOVING THROUGH...ETC. ONE THING THAT WILL NOT BE A CONCERN IS MOISTURE AS PRECIPITABLE WATER VALUES AVERAGE 150 PERCENT OF NORMAL DUE TO A GOOD SUBTROPICAL TAP. AS NOTED IN PREVIOUS AFD...RAIN CHANCES CONTINUE INTO THE EARLY PART OF NEXT WEEK AS THE UPPER TROUGH REMAINS WEST OF US AND VARIOUS SURFACE BOUNDARIES STALL OUT OVER THE AREA. THE LATEST GFS OPERATIONAL RUN IS MOVING IT THROUGH A LITTLE FASTER AS IT NOW HAS THE 500 MB TROUGH AXIS PASSING OUR CWA NEXT WED AFTERNOON. EC HAS ALSO COME IN LINE WITH THIS SOLUTION AND IS ACTUALLY ABOUT 12 HOURS FASTER THAN THE GFS. THIS A QUITE A DIFFERENCE FROM PREVIOUS EC WHICH DROPPED A SECOND LOW SOUTH BEHIND THE FIRST ONE AND DIDNT CLEAR THE SECOND LOW UNTIL NEXT SATURDAY. WILL HAVE TO KEEP AN EYE ON HOW THIS CHANGES OVER THE NEXT FEW DAYS...BUT IF LATEST SOLUTIONS ARE ON TRACK...COULD SEE THINGS DRY OUT A BIT NEXT WED INTO AT LEAST FRIDAY WHICH WOULD BE WELCOME NEWS FOR NEB STATE FAIR ATTENDEES. REGARDING TEMPERATURES...SOME COOLING EXPECTED ON SUNDAY WITH PASSAGE OF WEAK COLD FRONT AND THEN AGAIN ON WEDNESDAY AS MAIN TROUGH AND ANOTHER FRONT MOVES THROUGH. EXPECT HIGH TO BE IN THE LOWER 80S NORTH TO LOWER 90S SOUTH ON AVERAGE...ONCE AGAIN DEPENDING ON WHERE VARIOUS FRONTS STALL OUT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 700 PM CDT THU AUG 21 2014 MOST OF THE THUNDERSTORMS SHOULD STAY SOUTH OF THE KGRI AND KEAR...WITH JUST A SLIGHT CHANCE OF AN ISOLATED THUNDERSTORM AFTER SUNSET AS THE LOW LEVEL JET INCREASES TO THE SOUTH OF THE AREA. WILL KEEP THUNDER MENTION OUT OF THE TAF AT THIS POINT DUE TO THE LOW POPS. THE SFC WINDS HAVE BEEN AND WILL REMAIN LIGHT AND VARIABLE THROUGH MUCH OF THE TAF VALID PERIOD WITH A WEAK SFC BOUNDARY IN THE AREA. WILL CONTINUE TO CARRY THE CHANCE OF SLIGHT VISIBILITY REDUCTIONS AT BOTH KEAR AND KGRI IN THE FEW HOURS EITHER SIDE OF DAWN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...WESELY SHORT TERM...BRYANT LONG TERM...EWALD AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 PM CDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 354 PM CDT WED AUG 20 2014 RATHER DIFFICULT FORECAST TONIGHT. THERE HAVE BEEN LOTS OF MID LEVEL CLOUDS HANGING ACROSS THE AREA THIS AFTERNOON...AND HAVE KEPT TEMPERATURES DOWN A BIT. CLOUDS HAVE BEGUN TO CLEAR SLOWLY...AND ARE NOW ALLOWING FOR SOME HEATING AND INCREASING INSTABILITY. DO NOT HAVE A GOOD FEEL IN TERMS OF CONVECTION TONIGHT...AS MODELS HAVE BEEN INCONSISTENT AND PRIMARY FORCING REMAINS MOSTLY NORTH OF THE AREA. FOR THESE REASONS...WILL LOWER POPS A BIT. AS MENTIONED...INSTABILITY IS INCREASING WITH LITTLE SURFACE BASED CIN REMAINING ACROSS THE AREA. AN ELONGATED AREA OF LOW PRESSURE EXTENDS FROM WESTERN SD TO WESTERN KS...AND COULD BE THE FOCUS FOR ISOLATED STORM DEVELOPMENT THOUGH THE EVENING. A WARM FRONT ALSO EXTENDS FROM WEST TO EAST ACROSS NORTHERN NEBRASKA...AND COULD ALSO SERVE AS A FOCUS FOR STORM DEVELOPMENT. YET ANOTHER AREA TO WATCH WILL BE ACROSS NORTHEAST COLORADO THIS EVENING...AS HRRR MODEL CONTINUES TO INDICATE STORMS MOVING NORTHEAST INTO SOUTHWEST NEBRASKA THIS EVENING. SO LOTS OF AREAS TO WATCH...BUT LOW CONFIDENCE ON ANY ONE SCENARIO MATERIALIZING. WILL CONTINUE TO MONITOR. WEAK COOL FRONT WILL SETTLE JUST SOUTHEAST OF THE AREA THURSDAY. OVERALL SHOULD BE A FAIRLY QUITE WEATHER DAY...WITH LIGHT NORTH WINDS AND TEMPERATURES IN THE UPPER 80S AND LOWER 90S. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 354 PM CDT WED AUG 20 2014 MAIN FOCUS WILL BE THE STORM SYSTEM MOVING IN THIS WEEKEND WITH THUNDERSTORM CHANCES THURSDAY THROUGH SUNDAY. LOWERED PRECIPITATION CHANCES ACROSS THE SOUTHERN PART OF THE FORECAST AREA AS THE LATEST MODELS ARE TRENDING DRIER DUE TO LACK OF MOISTURE. KEPT THE POPS ACROSS THE NORTHWEST AS MODELS SEEM TO FAVOR STRONGER FORCING AND BETTER MOISTURE AS AN UPPER LEVEL SHORT WAVE TROF PUSHES ACROSS THE AREA. HELD OFF HIGHER PRECIPITATION CHANCES ACROSS THE SOUTHWEST UNTIL FRIDAY AFTERNOON AND EVENING AS CONFIDENCE IS GREATER IN THUNDERSTORM DEVELOPMENT AFTER 18Z. SYSTEM CURRENTLY ACROSS THE SOUTHWESTERN U.S. WILL CONTINUE TO ADVECT NORTHEASTWARD AND WILL COMBINE WITH THE NORTHERN SYSTEM CURRENTLY ACROSS THE GULF OF ALASKA. THE SOUTHWEST SYSTEM WILL TRANSPORT MOISTURE AND VORTICITY ACROSS THE FORECAST AREA FRIDAY AFTERNOON. BY 00Z SATURDAY PRECIPITABLE WATER INCREASES TO 150 PERCENT. SATURDAY NIGHT INTO SUNDAY...AN UPPER LEVEL SHORT WAVE TROF WILL PUSH ACROSS THE FORECAST AREA PUSHING THE RIDGE EASTWARD BRINGING COLDER TEMPERATURES WITH IT. HIGHS ON SUNDAY WILL BE AROUND 10 DEGREES COOLER THAN SATURDAY. COOLER TEMPERATURES WILL CONTINUE THROUGH WED WHEN NEXT TROF IS SET TO PUSH THROUGH THE AREA. THIS SYSTEM WILL BRING STRONG LIFT AS MODELS SUGGEST AN INCREASE IN OMEGA VALUES AND AN ABUNDANT AMOUNT OF MOISTURE WITH DEWPOINTS IN THE 60S CREATING A FAVORABLE THUNDERSTORM DEVELOPMENT TO BE IN PLACE THE NEXT SEVERAL DAYS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 108 PM CDT WED AUG 20 2014 A WARM FRONT WILL BE LOCATED FROM EAST TO WEST ACROSS NORTH CENTRAL AND NORTHEAST NEBRASKA THIS AFTERNOON. SCATTERED THUNDERSTORMS ARE POSSIBLE ALONG AND NORTH OF THE FRONT LATE THIS AFTERNOON AND EVENING. OTHER ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS NORTHEAST COLORADO AND COULD MOVE NORTHEAST INTO SOUTHWEST NEBRASKA THIS EVENING. WILL NOT INCLUDE MENTION IN THE OFFICIAL TAF FORECASTS...AS COVERAGE IS NOT EXPECTED TO BE WIDESPREAD. WINDS WILL GENERALLY BE LIGHT THROUGH TONIGHT. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TAYLOR LONG TERM...GOMEZ AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
334 PM CDT WED AUG 20 2014 .SHORT TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 334 PM CDT WED AUG 20 2014 UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE OVER THE NEXT WEEK WITH SEVERAL OPPORTUNITIES FOR THUNDERSTORMS. TIMING THESE CHANCES ALONG WITH INCREASE IN HEAT AND HUMIDITY ARE THE PRIMARY FORECAST CONCERNS. MORNING UPPER AIR CHARTS SHOWED MID LEVEL TROUGH EXTENDING FROM THE CANADIAN ROCKIES INTO SOUTHERN CALIFORNIA...WITH SOUTHWEST FLOW AHEAD OF THE TROUGH RIDING INTO THE NORTHERN PLAINS. UPPER RIDGE AXIS WAS CURRENTLY OVER THE MISSOURI RIVER VALLEY...BUT IS FORECAST TO SHIFT EAST AND FLATTEN A BIT ON THURSDAY. THIS WILL LEAVE OUR AREA UNDER SOUTHWEST FLOW ALOFT...WITH PATH FOR EJECTING SHORTWAVES OVER NEBRASKA AND THE DAKOTAS. ALSO OF NOTE WAS PLUME OF MID LEVEL MOISTURE EXTENDING FROM THE SOUTHERN BAJA INTO WESTERN KANSAS AND SOUTHWEST NEBRASKA. WITH ONLY A SLOW DRIFT TO WESTERN TROUGH...EXPECT THIS MOISTURE PLUME TO EXPAND OVER EASTERN NEBRASKA AND WESTERN IOWA AND REMAIN IN PLACE AT LEAST INTO THE WEEKEND. USING 700MB DEW POINT TEMPERATURES AS A PROXY...MODELS CONCUR WITH THIS EXPECTATION. THE RESULT OF THESE PARAMETERS WILL BE AN ATMOSPHERE PRIMED FOR SCATTERED CONVECTION AS SHORTWAVES ROLL INTO THE PLAINS. TIMING OF THOSE SHORTWAVES WILL PROVE DIFFICULT MORE THAN A DAY TO TWO OUT. HOWEVER MODELS AGREE ON A SIGNIFICANT SHORTWAVE MOVING INTO THE PLAINS FRIDAY NIGHT...OUR MOST LIKELY TIME FOR WIDESPREAD HEAVY RAINS. FOR TONIGHT...WATER VAPOR LOOPS IMPLY A SHORTWAVE IN WESTERN KANSAS THIS AFTERNOON...EXPECTED TO LIFT NORTHEAST ACROSS OUR CWA LATER THIS EVENING AND OVERNIGHT. GREATER THAN 7 C/KM MID LEVEL LAPSE RATES WILL BE IN PLACE ALONG WITH ABUNDANT MID LEVEL MOISTURE. EXPECT SCATTERED THUNDERSTORMS TO FIRE AFTER MIDNIGHT WHEN LOW LEVEL JET KICKS UP TO 35KT WITH APPROACH OF SHORTWAVE. MAIN AREA OF CONCERN WILL BE OVER OUR NORTHERN CWA THEN. HOWEVER THIS EVENING...CONVECTION FROM EARLIER THIS MORNING MOVING ACROSS IOWA LAID DOWN AN OUTFLOW BOUNDARY WHICH MOVED INTO SOUTHWEST IOWA AND NORTHERN MISSOURI. VISIBLE SATELLITE PICS SHOW A LINE OF CUMULUS ALONG THIS BOUNDARY...AND RAP MODEL SUGGESTS MLCAPE IS APPROACHING 3500 J/KG IN NORTHWEST MISSOURI ALONG WITH DIMINISHING CAP. LATEST RAP AND HRRR FORECASTS KEEP CONVECTION IN CHECK THERE...BUT HAVE ADDED SMALL POPS FOR SEVERAL HOURS THIS EVENING. OVERNIGHT CONVECTION SHOULD BE EXITING THE CWA OR DIMINISHING BY MID MORNING. EXPECT CLOUDS TO CLEAR ALLOWING FOR PLENTY OF INSOLATION IN THE AFTERNOON WITH TEMPERATURES WELL INTO THE 90S AND DEW POINTS CLOSE TO 70. A WEAK FRONTAL BOUNDARY IS FORECAST TO SETTLE INTO NORTHEAST NEBRASKA THURSDAY AFTERNOON BEHIND WEDNESDAY NIGHT SHORTWAVE...AND COULD FOCUS THUNDERSTORM CHANCES THERE. RELATIVELY WARM TEMPERATURES ALOFT WILL LIKELY SUPPRESS CONVECTION IN THE AFTERNOON...WITH BETTER CHANCES COMING LATER IN THE EVENING AS THE FRONT SETTLES SOUTH INTO SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AND MID LEVEL TEMPERATURES COOL A BIT. CONTINUED ISENTROPIC UPGLIDE OVER FRONTAL BOUNDARY IN MOIST ATMOSPHERE SUGGESTS AT LEAST SCATTERED CONVECTION IS POSSIBLE THROUGH THE NIGHT. MOST OF DAY FRIDAY SHOULD BE DRY AFTER MORNING STORMS IN THE SOUTH MOVE OFF TO THE EAST. FRONTAL BOUNDARY WILL BEGIN LIFTING TO THE NORTH DURING THE DAY WITH APPROACH OF STRONG SHORTWAVE FRIDAY NIGHT. INSTABILITY FORECASTS SHOW 2000-3000 J/KG OF SURFACE-BASED CAPE FRIDAY AFTERNOON...BUT SOUNDINGS SUGGEST A MODEST CAP WILL HOLD OFF STORMS UNTIL NEAR 00Z OR PROBABLY AFTER. CHANCES INCREASE MARKEDLY FRIDAY NIGHT AS SHORTWAVE AND SURFACE LOW MOVE NORTHEAST THROUGH THE CWA. CURRENT TRACK PLACES NORTHEAST NEBRASKA IN THE CORRIDOR OF HEAVIEST POTENTIAL RAINFALL WHERE PRECIPITABLE WATER WILL LIKELY EXCEED 2 INCHES. CURRENT HPC QPF PROGS PAINT ABOUT THREE-QUARTERS OF AN INCH OF RAIN IN NORTHEAST NEBRASKA...BUT WILL LIKELY SEE MUCH MORE THAN THAT IN LOCAL AREAS GIVEN MOISTURE AVAILABLE AND POTENTIAL FOR TRAINING OF STORMS. EXPECT ACTIVITY TO BE EXITING TO OUR NORTHEAST SATURDAY MORNING...BUT LEFTOVER BAROCLINIC ZONE AND WIND SHIFT WILL REMAIN IN PLACE FOR THE POTENTIAL FOR MORE STORMS LATER IN THE DAY SATURDAY. WILL MAINTAIN A SMALL CHANCE FOR ADDITIONAL AFTERNOON STORMS...EXPECTING SUBSIDENCE BEHIND EXITING SHORTWAVE TO SUPPRESS CONVECTION MOST OF THE AFTERNOON. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 334 PM CDT WED AUG 20 2014 CONTINUED CHANCES OF THUNDERSTORMS WILL REMAIN JUST ABOUT EACH PERIOD IN THE LONGER TERM FORECAST THROUGH WEDNESDAY. WESTERN UPPER TROUGH WILL SLOWLY DRIFT FROM THE ROCKIES SATURDAY NIGHT INTO THE PLAINS BY WEDNESDAY. ECMWF IS A LITTLE MORE PROGRESSIVE THAN THE GFS WITH THIS MOVEMENT...BUT EVEN THE ECMWF LEAVES SOME SEMBLANCE OF A TROUGH/LOW IN THE PLAINS THEN. USING A BLEND OF ECMWF AND GFS...AND WHERE SOME CONSISTENCY IS SHOWN...BEST CHANCES FOR MORE WIDESPREAD CONVECTION IS EXPECTED MONDAY NIGHT INTO TUESDAY...THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY. BEFORE THEN...IMPULSES RIDING THROUGH MID LEVEL FLOW COULD SPARK AREAS OF STORMS AT JUST ABOUT ANY TIME AS FRONTAL BOUNDARY MEANDERS NORTH AND SOUTH THROUGH THE CWA AHEAD OF AND BEHIND EACH WAVE. TEMPERATURES SHOULD MODERATE SOME THROUGH THE PERIOD...BEGINNING WITH SUNDAY IN THE 80S TO NEAR 90...THEN RANGING FROM THE UPPER 70S TO MIDDLE 80S MONDAY THROUGH WEDNESDAY. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1242 PM CDT WED AUG 20 2014 ONGOING CONVECTION OVER NORTHEAST NEBRASKA HAS BEEN LIFTING NORTH DURING THE MORNING AND THIS TREND IS EXPECTED TO CONTINUE INTO THE AFTERNOON AS WARM FRONT MOVES NORTH TO ALONG THE NEBRASKA SOUTH DAKOTA BORDER BY 00Z. SOME CHANCE OF THUNDERSTORMS AFTER 06Z AT KOFK AS WEAK TROUGH MOVES INTO NORTH CENTRAL NEBRASKA BUT LESS LIKELY AT KOMA AND KLNK WHERE SOME CAPPING EXPECTED. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORM ACTIVITY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN LONG TERM...DERGAN AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1252 PM CDT WED AUG 20 2014 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5" AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR THETA-E ADV/315K ISENTROPIC UPGLIDE. LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT OF THE CWA BY 18Z THIS AFTN. HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS. TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT. THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN CWA...THUS WILL MENTION IN ZFP. .LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK. GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1242 PM CDT WED AUG 20 2014 ONGOING CONVECTION OVER NORTHEAST NEBRASKA HAS BEEN LIFTING NORTH DURING THE MORNING AND THIS TREND IS EXPECTED TO CONTINUE INTO THE AFTERNOON AS WARM FRONT MOVES NORTH TO ALONG THE NEBRASKA SOUTH DAKOTA BORDER BY 00Z. SOME CHANCE OF THUNDERSTORMS AFTER 06Z AT KOFK AS WEAK TROUGH MOVES INTO NORTH CENTRAL NEBRASKA BUT LESS LIKELY AT KOMA AND KLNK WHERE SOME CAPPING EXPECTED. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORM ACTIVITY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DEE LONG TERM...DEE AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
549 AM CDT WED AUG 20 2014 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5" AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR THETA-E ADV/315K ISENTROPIC UPGLIDE. LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT OF THE CWA BY 18Z THIS AFTN. HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS. TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT. THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN CWA...THUS WILL MENTION IN ZFP. .LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK. GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS. && .AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 550 AM CDT WED AUG 20 2014 CONVECTIVE ACTIVITY THIS MORNING SHOULD STAY NORTHEAST THROUGH EAST OF THE TAF SITES WITH A GENERAL THINNING OF CLOUDS THIS MORNING. OUTFLOW COULD BRING MORE OF A ENE COMPONENT TO SFC WINDS EARLY...ESPECIALLY AT KOFK...BUT THEY SHOULD BECOME SSE BY LATE MORNING AND BECOME GUSTY AT ALL LOCATIONS THIS AFTN. A LOW LEVEL JET WILL STRENGTHEN AGAIN TONIGHT AND IF SFC WINDS DECREASE ENOUGH...LOW LEVEL WIND SHEAR CONDITIONS COULD DEVELOP. THIS WILL BE FURTHER EVALUATED IN LATER TAFS. TSTMS WERE EXPECTED TO DEVELOP LATE THIS AFTN/TNGT EITHER NEAR A WARM FRONT ALONG THE SD BORDER OR IN AN AREA OF LOW PRESSURE OVER WRN NEBR. SOME OF THIS ACTIVITY COULD APPROACH THE KOFK SITE AND A PROB30 GROUP WAS CARRIED TO ACCOUNT FOR THE RISK THERE LATER TONIGHT. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DEE LONG TERM...DEE AVIATION...CHERMOK
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
325 AM CDT WED AUG 20 2014 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 MESO ANALYSIS THIS MORNING INDICATING HIGH DEGREE OF MOISTURE/INSTABILITY IN PLACE OVER THE REGION WITH PWS OVER 1.5" AND MUCAPES AROUND 2000 J/KG. MEANWHILE INTENSE LLVL MOISTURE ADV WAS FEEDING CONVECTIVE ACTIVITY WHICH HAS BLOSSOMED OVER CNTRL NEB AND CNTRL SD ALONG AXIS OF DEEP LYR MOIST CONVERGENCE/BNDRY LYR THETA-E ADV/315K ISENTROPIC UPGLIDE. LAST SEVERAL RUNS OF HIRES HRRR SUGGESTING LINE OF CONVECTION ORIENTED NW-SE WILL FIRE OVER THE CWA SOMETIME TWD SUNRISE THIS MORNING. HRRR THEN LIFTS ACTIVITY NEWD TWD THE UPPER MIDWEST AND OUT OF THE CWA BY 18Z THIS AFTN. HEADING INTO THIS WEEKEND...GOOD MODEL AGREEMENT HIGH PRESSURE DOME WILL BUILD OVER THE SERN STATES WILL ACT AS A BLOCK RESULTING IN UPSTREAM AMPLIFICATION OF UPPER TROF OVER THE WRN CONUS. IN ADDITION...BULK OF PCPN ACTIVITY IS PROGGED TO BE NOCTURNAL IN NATURE THE REST OF THIS WEEK WITH BULK OF RAINFALL FOUND MAINLY NORTH OF THE CWA. HOWEVER...QUITE PROBABLE THE CWA WILL SEE ITS FAIR SHARE OF MUCH NEEDED PCPN THE NEXT SEVERAL DAYS. TONIGHT...EXPECT CONVECTION TO FIRE FROM ERN SD TO SW NEB ALONG INSTABILITY AXIS WHERE BNDRY LYR THETA-E CONVG WILL BE MOST PREVALENT. ACTIVITY PROGGED TO EVENTUALLY ORGANIZE INTO A COMPLEX AND SLOWLY MIGRATE EWD OVER ERN SD OVERNIGHT. IS LIKELY THAT SRN PORTION OF MCS WILL PUSH DEEP INTO THE CWA...THUS FEEL COMPELLED PUSH POPS INTO THE LIKELY CAT DURING THE OVERNIGHT TONIGHT. THURSDAY NIGHT CONVECTION NOT LOOKING ALL THAT IMPRESSIVE AT THIS POINT AND ANY ACTIVITY THAT DOES DEVELOP WILL BE LIGHTLY SCATTERED IN NATURE AT BEST. THEREFORE TOKEN LOW POPS SEEM TO BE THE BEST FIT FOR NOW. FRIDAY NIGHT THOUGH LOOKING RATHER PROMISING FOR GENEROUS RAINFALL ASSOCIATED WITH ANTICIPATED NIGHTTIME COMPLEX. ENVIRONMENT AT THAT TIME WILL BE PRIME WITH WARM CLOUD DEPTH OF 4K METERS...PWS MORE THAN 2"...KI AOA 40...LLVL JET MOISTURE TRANSPORT FEED. MOST LIKELY THAT HEAVIER RAINFALL AMOUNTS WILL BE FOUND OVER THE NRN CWA...THUS WILL MENTION IN ZFP. .LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY) ISSUED AT 323 AM CDT WED AUG 20 2014 FEATURE OF INTEREST STILL IS UPPER TROF OVER WRN CONUS RESPONSE TO BLOCKING HIGH PRESSURE DOME OVER THE SERN CONUS WITH RATHER COOL CANADIAN AIRMASS SWEEPING INTO THE NRN/CNTRL PLAINS EARLY NEXT WEEK. GOING FCST WITH MAX TEMPS GENERALLY IN THE MID/UPPER 70S MON/TUES/WED STILL LOOK REASONABLE FOR NOW. PCPN CHANCES IN THE EXT PDS REMAINS CENTERED AROUND VERY SLOW MOVING COLD FRONTAL LEADING THE CANADIAN AIR MASS INTO THE REGION FOLLOWED BY POST FRONTAL PCPN ASSOCIATED WITH APPROACHING UPPER TROF. WITH ECM/GFS QPF IN RATHER GOOD AGREEMENT...HAVE DECIDED TO BUMP POPS UP MON-WED PDS. && .AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1131 PM CDT TUE AUG 19 2014 VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE TAF PERIOD. HIGH BASED CONVECTION IS EXPECTED TO DEVELOP IN A NW-SE ARC ACROSS THE AREA THROUGH THE OVERNIGHT PERIOD. A FEW MVFR CONDITIONS ARE POSSIBLE DURING THIS TIME PERIOD AND HAVE CONTINUED A TEMPO GROUP FOR THIS AT BOTH KOFK AND KOMA. KLNK SHOULD STAY OUT OF THE TSTMS. SOUTHEASTERLY WINDS WILL INCREASE WEDNESDAY AFTERNOON WITH GUSTS TO NEAR 25KTS BEHIND A WARM FRONT PUSHING NORTH INTO SD. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DEE LONG TERM...DEE AVIATION...KERN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
102 AM CDT WED AUG 20 2014 .UPDATE... ISSUED AT 521 PM CDT TUE AUG 19 2014 UPDATED TO INCLUDE A SLIGHT CHANCE FOR THUNDERSTORMS FROM SWRN NEBR INTO CENTRAL NEBRASKA AS THIS EVENING PROGRESSES. LATEST REGIONAL RADAR MOSAIC SHOWS SCATTERED THUNDERSTORMS FROM NEAR SCOTTSBLUFF THROUGH FORT MORGAN AND LAST CHANCE COLORADO. THE LATEST HRRR AND RAP13 INDICATE THIS TO PUSH NORTHEAST AND INCREASE IN COVERAGE INTO WRN NEBR THIS EVENING. RECENT ISOLATED DEVELOPMENT NOW IN SHERIDAN AND CHERRY COUNTY ATTM. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 337 PM CDT TUE AUG 19 2014 SHORTWAVE RIDGING ALOFT CURRENTLY RESIDES OVER THE AREA...WITH VERY LITTLE IN THE WAY OF CLOUD COVER EXCEPT FOR SOME HIGH CIRRUS CLOUDS. SHORT TERM HRRR MODEL SUGGESTS THUNDERSTORMS WILL DEVELOP OVER THE HIGHER TERRAIN TO THE WEST LATE THIS AFTERNOON...AND THEN DRIFT EAST INTO WESTERN NEBRASKA THIS EVENING. LATEST VISIBLE SATELLITE TRENDS CONFIRMS THIS THINKING...WITH QUITE A BIT IN THE WAY OF TOWERING CUMULUS FROM CHEYENNE DOWN THROUGH THE DENVER METRO. SOUTHERLY LOW LEVEL JET WILL INCREASE TO AROUND 35 KTS THIS EVENING...WHICH MAY HELP SUPPORT STORMS AS THEY TRACK EAST. NOT EXPECTING COVERAGE TO BE WIDESPREAD...AND DUE TO THE RIDGING ALOFT...NOT REAL CONFIDENT ON HOW FAR EAST STORMS WILL MAKE IT. LATER TONIGHT...DECENT MID LEVEL INSTABILITY DEVELOPS ACROSS NORTH CENTRAL INTO NORTHEAST NEBRASKA...AND EXPECT AT LEAST SCATTERED COVERAGE OF ELEVATED THUNDERSTORMS TO DEVELOP WITHIN AREA OF ISENTROPIC ASCENT. A SURFACE TROUGH WILL EXTEND FROM NORTHEAST TO SOUTHWEST WEDNESDAY AFTERNOON...AND SHOULD BE THE FOCUS FOR SCATTERED LATE AFTERNOON THUNDERSTORMS. THE NAM MODEL IS THE FARTHEST EAST WITH THE TROUGH...WHILE THE NMM...ARW AND GEM REGIONAL HOLD THE TROUGH BACK FROM ROUGHLY AINSWORTH TO IMPERIAL. DECENT INSTABILITY DEVELOPS BY AFTERNOON ALONG AND EAST OF THE TROUGH...WITH SURFACE BASED CAPES APPROACHING 4000 J/KG. A BELT OF STRONGER MID LEVEL WINDS WILL ALSO BE PRESENT BY AFTERNOON ON THE SOUTHERN FLANK OF A SHORTWAVE CROSSING THE NORTHERN PLAINS. THE SYNOPTIC SET UP APPEARS SIMILAR TO THE SUNDAY SEVERE EVENT...AND AGREE WITH THE STORM PREDICTION CENTER SLIGHT RISK FOR SEVERE STORMS EAST OF HIGHWAY 83. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 337 PM CDT TUE AUG 19 2014 THE WEAK FRONT WILL CROSS CENTRAL NEBRASKA WEDNESDAY NIGHT AND GENERATE A BAND OF THUNDERSTORMS...ESPECIALLY IN CENTRAL AND NORTH CENTRAL NEBRASKA. MODEL OUTPUT STATISTICS INDICATE PROBABILITY/ COVERAGE OF 20-30 PERCENT IN THE SANDHILLS AND 30-40 PERCENT IN CENTRAL AND NORTH CENTRAL NEBRASKA. THAT SEEMS REASONABLE. SURFACE BASED CAPE IN CENTRAL AND NORTH CENTRAL NEBRASKA IS PRETTY HIGH AT 3500-4000J/KG WITH BULK SHEAR (0-6KM) AROUND 30KT. WITH STORM MOTION 240-260 AT 15-25KT...STORM RELATIVE HELICITY IS EXPECTED TO BE 110-200. SEVERE STORMS ARE POSSIBLE INTO THE EVENING...THOUGH WE WILL NOT INCLUDE THE MENTION IN THE FORECAST FOR WEDNESDAY NIGHT. A BOUNDARY LIFTING NORTH INTO SOUTHERN NEBRASKA WILL BRING THE POSSIBILITY OF THUNDERSTORMS TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA THURSDAY NIGHT. AS THE BOUNDARY MAKES ITS WAY A LITTLE FARTHER NORTH FRIDAY...THERE IS A POSSIBILITY OF THUNDERSTORMS IN CENTRAL AND NORTHERN NEBRASKA. FINALLY...SATURDAY NIGHT AND SUNDAY...A COOL FRONT COMES ACROSS NEBRASKA AND THE PATTERN IS NOT AS FAVORABLE FOR STRONG CONVECTION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 102 AM CDT WED AUG 20 2014 AN AREA OF LIGHT SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS WILL MOVE NORTHEAST ACROSS SOUTHWEST INTO EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA OVERNIGHT. FOR WEDNESDAY...A CHANCE FOR THUNDERSTORMS AT KLBF AFTER 23Z/21ST AND INCLUDED IN A PROB30 FOR 5SM TSRA BKN070CB. EXPECT TSRA TO DEVELOP AND REMAIN EAST OF KVTN TERMINAL AND DID NOT INCLUDE THIS TAF ISSUANCE. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ROBERG SHORT TERM...TAYLOR LONG TERM...SPRINGER AVIATION...POWER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1017 PM EDT THU AUG 21 2014 .SYNOPSIS... A LOW PRESSURE AREA OVER THE GREAT LAKES WILL BRING SHOWERS AND A CHANCE OF THUNDERSTORMS OVER NORTHERN NEW YORK TONIGHT. THERE WILL BE A SLIGHT CHANCE FOR SHOWERS ON FRIDAY. A RIDGE OF HIGH PRESSURE WILL BUILD SOUTH FROM CANADA FRIDAY NIGHT AND WILL REMAIN OVER THE NORTH COUNTRY INTO EARLY NEXT WEEK...WITH FAIR AND DRY WEATHER EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/... AS OF 1017 PM EDT THURSDAY...FORECAST REMAINS IN OVERALL GOOD SHAPE WITH SCT/NUMEROUS SHOWERS EXPECTED OVERNIGHT...MOST PREVALENT ACROSS THE CHAMPLAIN VALLEY AND INTO PORTIONS OF CENTRAL/SC VT. FORECAST AREA LIES BENEATH LOW TO MID LEVEL SHEAR/DIFFLUENT ZONE BETWEEN WEAKENING UPPER LOW ACROSS SRN ONTARIO INTO CENTRAL NY...AND HIGH PRESSURE BUILDING SOUTHWARD FROM CENTRAL QUEBEC. THIS WILL ALLOW SHOWERS TO CONTINUE MUCH OF THE NIGHT ACROSS AFOREMENTIONED AREAS. IF YOU BELIEVE THE RAP OUTPUT LITERAL...ACTIVITY MAY FILL IN QUITE SOLIDLY ACROSS VT OUTSIDE NERN PORTIONS OF THE STATE OVERNIGHT...LEADING TO QUITE A SOAKER. INDEED...3-HRLY ESTIMATES ALONG THE SHEAR ZONE HAVE RANGED FROM 0.25 TO 0.75 INCHES WITH SOME PORTIONS OF ADDISON/NRN WINDSOR COUNTIES HAVING PICKED UP IN EXCESS OF 1 INCH. REST OF FORECAST REMAINS ON TRACK WITH CLOUDY SKIES...PATCHY BR/FG HERE AND THERE AND LOWS FROM THE UPPER 50S TO LOWER 60S. HAVE A GREAT NIGHT. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 335 PM EDT THURSDAY...UPPER LOW THEN CONTINUES TO SHIFT EASTWARD INTO THE COASTAL WATERS OF NEW ENGLAND FRIDAY. NAM AND GFS DEPICT A WEAK SHORTWAVE TROUGH ROTATING AROUND AND PASSING THROUGH THE NORTH COUNTRY DURING PEAK HEATING. THEREFORE...EXPECT AN INCREASE IN DIURNAL SHOWERS FRIDAY WITH CHANCE POPS FORECAST DURING THE AFTN HOURS...TRENDING DRIER BY EVENING. MOSTLY CLOUDY/OVERCAST TRENDS TO PARTLY/MOSTLY CLOUDY BY AFTN FROM SOUTH TO NORTH WITH MORE SIGNIFICANT CLEARING EXPECTED AFTER MIDNIGHT. HIGHS FRIDAY ARE COOLEST IN SOUTHERN VT AND ESSEX COUNTY NY AND WARMEST NEAR THE CANADIAN BORDER...UPPER 60S TO MID 70S WITH LOWS IN THE UPPER 40S TO UPPER 50S. HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH WITH DRY WEATHER FOR SATURDAY. WHILE CLEARING SKIES AND WARMER TEMPS ARE EXPECTED FOR MOST OF THE NORTH COUNTRY...EASTERLY TRAJECTORIES AND SATURATED NAM/BTV-4 LOW-LEVEL RH PROGS SUGGEST POTENTIAL FOR MARINE LAYER/STRATUS IN EASTERN VT. WITH 850 MB TEMPS FROM +9C IN EASTERN VT TO AROUND +11C ELSEWHERE...LOOKING AT HIGHS ONLY AROUND 70 IN EASTERN VT TO MID/UPPER 70S FOR THE REST OF THE NORTH COUNTRY. GOOD RADIATIONAL COOLING SATURDAY NIGHT ALLOWS LOWS TO RANGE FROM UPPER 40S TO UPPER 50S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 335 PM EDT THURSDAY...NO BIG CHANGES TO PREVIOUS FORECASTS FOR THE TIME. MUCH OF THE PERIOD WILL BE DOMINATED BY STRONG RIDGING ALOFT AND AT THE SURFACE (AKA: RIDGOSAUROUS). 12Z SUITE OF MODEL GUIDANCE REMAINS FAIRLY SIMILAR TO EACH OTHER AND PRIOR RUNS. NOTED THAT THE 12Z ECMWF TRENDED TOWARD THE GFS FOR THE SCENARIO ON WEDNESDAY AND IS NOW SHOWING A STRONGER RIDGE INTO MID WEEK. MODELS DIVERGE FOR THURSDAY, WITH EURO SHOWING A FASTER/MORE AMPLIFIED TROUGH BREAKING DOWN THE RIDGE. THE DIFFERENCES CONTINUE FOR BEYOND THE OFFICIAL PERIOD I`M FORECASTING FOR, BUT AN EARLY LOOK AT GUIDANCE FOR LABOR DAY WEEKEND SEEMS TO INDICATE IT WILL FEATURE SEASONABLE TEMPERATURES AND MOSTLY DRY CONDITIONS. WE`LL SEE. AS FOR THE DAILY SPECIFICS, JUST READ ON: SUNDAY...SURFACE HIGH JUST A LITTLE NORTH OF HERE SO CONTINUED LIGHT EASTERLY FLOW. 850 MPH TEMPERATURES RISE TO 11-13C (WARMEST IN WESTERN HALF), WHICH WILL SUPPORT HIGHS IN THE MID 70S EAST TO LOW 80S WEST. STRONG SUBSIDENCE WILL KEEP ANY CLOUDS TO A MINIMUM. AT NIGHT, CLEAR AND CALM SO LOOK FOR PATCHY VALLEY FOG. MONDAY...SURFACE HIGH OVERHEAD, SO HARDLY A BREEZE. 850MB TEMPERATURES UP ANOTHER DEGREE TO ABOUT 12-14C, SO ADD ABOUT 1-3F FOR THE HIGH TEMPERATURE FROM SUNDAY -- LOWER 80S PRETTY MUCH AREA WIDE. MONDAY NIGHT, MORE CLEAR/CALM/PATCHY FOG. TUESDAY...HIGH SOUTH OF HERE, SO A BIT OF A WEST/SOUTHWEST FLOW GETS ESTABLISHED. 850MB TEMPERATURES UP ANOTHER DEGREE. WITH WEST FLOW, THIS SHOULD ALSO HELP WITH SOME DOWNSLOPE INTO THE CHAMPLAIN VALLEY SO I`D EXPECT MID 80S TO BE A SOLID BET IN THE VALLEYS. THE EURO RUNS SEVERAL DEGREES COOLER, SO HAVE LEANED MORE TOWARD THE WARMER GFS TEMPERATURES. OVERNIGHT WILL FEATURE CLEAR/CALM/PATCHY FOG. WEDNESDAY...HIGH SOUTH OF HERE, SO THE AREA IS SOLIDLY IN WEST/SOUTHWEST FLOW. 850MB TEMPERATURES PUSHING 15-16C WHICH SUPPORT HIGHS IN THE MID TO UPPER 80S IN SPOTS. ADD IN SOME DOWNSLOPING OFF THE ADIRONDACKS, AND I THINK PARTS OF THE CHAMPLAIN VALLEY COULD MAKE A RUN AT 90F. I DID INCREASE TEMPERATURES SEVERAL DEGREES OVER THE BLEND OF GUIDANCE WHICH WAS BIASED A BIT COOL DUE TO THE EURO AND CLIMO IN THE MOS. THAT BLEND GAVE ME 81F FOR BTV. MEX GUIDANCE WAS 83F. I WENT 85F. WE`LL SEE HOW FUTURE GUIDANCE GOES AND IF THE TREND TO BE WARMER IS NEEDED. WEDNESDAY NIGHT AGAIN CLEAR/CALM/PATCHY FOG. THURSDAY...THIS IS WHEN IT LOOKS LIKE THE PATTERN WILL BEGIN TO BREAK DOWN. AS MENTIONED EARLIER, THE EURO IS MORE AGGRESSIVE WITH A SHORTWAVE. AT THIS POINT, BEST COURSE IS TO TAKE A BLEND. HAVE PAINTED IN CHANCE LEVEL OF POPS FOR SCATTERED THUNDERSTORMS. TEMPERATURES MAY AGAIN BE VERY WARM IF THE GFS IS RIGHT. OR COOLER IF THE EURO IS RIGHT. STUCK WITH THE BLEND. WHICH STILL FEATURES LOTS OF LOWER 80S. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... THROUGH 00Z SATURDAY...ESSENTIALLY LOOKING AT VFR AND MVFR CONDITIONS THROUGH ABOUT 12Z WITH PLENTY OF CLOUDS...SHOWERS...AND FOG LINGERING OVER THE AREA TONIGHT THROUGH THE EARLY MORNING HOURS. AFTER 12Z ANY PRECIPITATION COMES TO AN END AND VISIBILITIES IMPROVE WITH BROKEN CEILINGS ABOVE 3000 FEET. WINDS WILL HAVE AN EASTERLY COMPONENT TO THEM TONIGHT...BUT AT SPEEDS GENERALLY UNDER 10 KNOTS. THE EXCEPTION TO THIS WILL BE AT KRUT WHERE SOUTHEAST WINDS WILL GUST TO 20 KNOTS THROUGH ABOUT 06Z. OUTLOOK 00Z SATURDAY THROUGH TUESDAY...VFR WITH THE FOLLOWING EXCEPTIONS -- BRIEF MVFR IN ANY SHOWERS THROUGH 06Z SATURDAY. LOCALIZED IFR IN LATE NIGHT FOG (MAINLY AN ISSUE FOR MPV AND SLK). && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...JMG SHORT TERM...LOCONTO LONG TERM...NASH AVIATION...EVENSON/NASH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
955 PM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL DIVE SOUTHEAST INTO OUR REGION FROM THE OHIO VALLEY AND MIDWEST. A COLD FRONT LOCATED ACROSS THE MID ATLANTIC ON FRIDAY WILL MOVE SOUTH THROUGH THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 310 PM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST HAVE SEEN MORE MIXING THAN IN THE EAST WITH MORE WESTERLY FLOW AND DRIER AIR ALOFT. MLCAPE RANGES FROM LESS THAN 1000 J/KG TO AS MUCH AS 2000 J/KG. THE CUMULUS FIELD OVER THE COASTAL PLAIN IN A BIT MORE PRONOUNCED WHERE LOW-LEVEL CONVERGENCE AND INSTABILITY OVERLAP. TO THE NORTHWEST...A SERIES OF UPPER DISTURBANCES ARE MOVING ACROSS KENTUCKY/WEST VIRGINIA. THE MEAN FLOW MAY CAUSE SOME OF THE SCATTERED CONVECTION THAT TRIGGERS FROM THIS DISTURBANCE TO MOVE SOUTHEAST INTO THE NORTHWEST OR NORTHERN PIEDMONT BY THIS EVENING. HOWEVER...THE HRRR CONTINUES TO SHOW VERY LITTLE ACTIVITY THIS AFTERNOON. EFFECTIVE SHEAR WILL INCREASE 25-30KT ACROSS THE NORTH THIS EVENING...SO IF ANY STORMS CAN GET GOING THERE...THEY WILL STAND THE BEST CHANCE OF BEING STRONG TO SEVER WITH THE LOSS OF HEATING...THE CHANCE OF SHOWERS OR STORMS WIL SLOWLY DIMINISH...THOUGH A CHANCE MAY LINGER ACROSS THE NORTH THROUGH MIDNIGHT AS CONVECTION OVER VIRGINIA EVOLVES. LOWS IN THE LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 235 PM THURSDAY... FRIDAY WILL BE ANOTHER DAY WITH NORTHWESTERLY FLOW ALOFT...SURFACE TROUGHING IN THE EAST...AND THE POTENTIAL FOR A DISTURBANCE OR TWO TO CROSS THE AREA. THE MAIN DISTURBANCES IN QUESTION ARE LIKELY ASSOCIATED WITH CONVECTION OVER THE UPPER MIDWEST...AND ARE PROGGED TO MOVE SOUTHEAST ACROSS THE AREA LATE FRIDAY AFTERNOON. TIMING OF SUCH A FEATURE IS STILL TOUGH THIS FAR OUT...SO CONFIDENCE IN ITS ADDITIONAL SUPPORT FOR AFTERNOON CONVECTION IS LOW. DEEP MIXING IS EXPECTED AGAIN DURING THE AFTERNOON...WHICH WILL TEMPER INSTABILITY A LITTLE IN THE WEST WHERE DEWPOINTS SHOULD DROP BACK INTO THE MID 60S. THERMAL PROFILES ARE RELATIVELY SIMILAR TO TODAY...SO MLCAPE SHOULD AGAIN RANGE FROM LESS THAN 1000 J/KG IN THE WEST TO OVER 1500 J/KG IN THE EAST. A BELT OF STRONGER WESTERLIES OVER THE CENTRAL APPALACHIANS WILL LIKELY ENHANCE CONVECTION OVER VA...AND SOME OF THIS ACTIVITY MAY DRIFT SOUTH INTO THE NORTHERN PORTIONS OF THE CWA BY FRIDAY EVENING...SO WILL HAVE THE HIGHEST CHANCE POPS ACROSS THE NORTH...WHILE AREAS IN SOUTHERN PIEDMONT MAY STAY DRY. H85 TEMPS ARE FORECAST TO BE ABOVE 20C AGAIN FRIDAY AND WITH DEEP MIXING RESULTS IN MID TO POSSIBLY UPPER 90S. DEWPOINTS ARE FORECAST TO MIX OUT A LITTLE MORE IN THE EAST THAN TODAY...THOUGH ONLY SLIGHTLY...SO HEAT INDEX VALUES SHOULD AGAIN HOLD AROUND 100F IN THE SOUTHEAST. DEPENDING ON HOW MUCH CONVECTION THERE IS TO THE NORTH FRIDAY EVENING...THERE IS THE POTENTIAL FOR A WEAK EFFECTIVE FRONT INTO THE NORTHERN COASTAL PLAIN FRIDAY NIGHT...NECESSITATING POPS THROUGH THE OVERNIGHT HOURS. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 145 PM THURSDAY... THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW. THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY. TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE REMAINDER OF THE WEEK. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 800 PM THURSDAY... 24-HR TAF PERIOD: SCATTERED SHOWERS AND STORMS WILL PERSIST THROUGH 06Z AS THEY TRACK TOWARD THE SOUTH/SOUTHEAST...THOUGH ACTIVITY IS EXPECTED TO DIMINISH IN COVERAGE AND INTENSITY THROUGH THAT TIME. SUB-VFR FOG AND/OR LOW CEILINGS ARE LIKELY TO DEVELOP OVERNIGHT ACROSS PORTIONS OF CENTRAL NC...ESP WHERE MEASURABLE RAINFALL OCCURS LATE THIS EVENING. DIURNAL CONVECTION WILL BE POSSIBLE AGAIN FRI AFTERNOON AND EVENING...WITH THE BEST CHANCE AT THE RDU/RWI TERMINALS. LOOKING AHEAD: DIURNAL CONVECTION IS EXPECTED AGAIN ON SAT... ENHANCED BY THE PASSAGE OF A BACK DOOR COLD FRONT FROM THE NORTH/NE SAT EVE/NIGHT. WIDESPREAD IFR CEILINGS ARE EXPECTED IN THE WAKE OF THE BACKDOOR COLD FRONT SAT NIGHT/SUN MORNING...POSSIBLY PERSISTING THROUGH THE DAY AND INTO SUN NIGHT. AN UNSEASONABLY AMPLIFIED SYNOPTIC PATTERN KNOWN AS AN `OMEGA BLOCK` WILL PREVAIL THROUGH THE MIDDLE OF NEXT WEEK...CENTERED OVER THE APPALACHIANS. AS A RESULT... AT THIS TIME EXPECT VFR CONDITIONS EARLY/MID NEXT WEEK...THOUGH A PERSISTENT EAST/ENE LOW-LEVEL FLOW MAY ALLOW ENOUGH MOISTURE ADVECTION FOR LOW-TOPPED SHOWER ACTIVITY AT SOME POINT. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLS SHORT TERM...BLS LONG TERM...MLM AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
633 PM EDT WED AUG 20 2014 .SYNOPSIS... HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT COUPLE OF DAYS BEFORE SOME COOLING DURING THE WEEKEND AS A COLD FRONT MOVES THROUGH. LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 6:30 PM WEDNESDAY...CONVECTION HAS FADED AREA-WIDE AND WITH LITTLE IN THE WAY OF TRIGGERS TO RE-INITIATE STORM DEVELOPMENT HAVE DROPPED POPS TO SLIGHT CHANCE FOR THE NEXT FEW HOURS...AND DRY AFTER MIDNIGHT. GIVEN SPEED OF STORM AND SHOWER DISSIPATION...MAY FURTHER REDUCE CHANCES TO NEAR NIL IN AN HOUR OR SO. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS: DAYBREAK THURSDAY LOW/MID 70S MOST LOCATIONS WITH UPPER 70S TO NEAR 80 CLOSER TO THE IMMEDIATE COAST AND ICW LOCALS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 315 PM WEDNESDAY...THIS PERIOD WILL BE MARKED BY A RETURN OF SWELTERING HEAT AND HUMIDITY TO THE EASTERN CAROLINAS. AN UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE GULF COAST WILL EXPAND EASTWARD ON THU AS 500 MB HEIGHTS RISE OVER OUR CWA. 850 MB TEMPS CLIMB TO 19-20C ON THU AND 20-21C ON FRI AS NORTHWEST FLOW ALOFT RESULTS IN DOWNSLOPE ADIABATIC WARMING. EXPECT HIGHS ON THU/FRI TO REACH THE MID TO UPPER 90S EVERYWHERE AWAY FROM THE IMMEDIATE COAST. GIVEN THE LARGE VARIATIONS BETWEEN GFS/NAM DEWPOINTS ATTM...HAVE OPTED FOR A GMOS/NAM BLEND THAT GIVES DEWPOINTS IN THE LOW TO MID 70S. THIS YIELDS HEAT INDICES OF 100-105F ACROSS THE AREA BOTH DAYS. THE MOST OPPRESSIVE HEAT WILL BE FELT ACROSS NORTHEAST SOUTH CAROLINA...WHERE HEAT INDICES ARE EXPECTED TO EXCEED HEAT ADVISORY CRITERIA OF 105F. I WILL RAISE A HEAT ADVISORY FOR THU FOR ALL OF OUR SOUTH CAROLINA COUNTIES...EXCEPT DILLON AND MARLBORO COUNTY. CONDITIONS MAY WARRANT A HEAT ADVISORY FOR FRI AS WELL. UPPER RIDGING ON THU WILL WORK TO SUPPRESS CONVECTION DURING PEAK HEATING...AND THE LATEST GFS/NAM RUNS SHOW LITTLE TO NO ACTIVITY FOR US DURING THE DAY. WILL STILL MAINTAIN SLIGHT CHC POPS DURING THE AFTN HOURS AS MESOSCALE BOUNDARIES LIKE THE SEA BREEZE PROVIDE SOME ENHANCED LIFT. MOST ACTIVITY WILL BE DISPLACED NORTH OF OUR CWA ALONG WITH THE DEEPER MOISTURE. PWATS INCREASE TO AROUND 2.0 INCHES ON FRI AHEAD OF AN APPROACHING BACKDOOR COLD FRONT. AN UPPER DISTURBANCE EMBEDDED WITHIN THE NORTHWEST FLOW WILL ALSO MOVE OVERHEAD LATE FRI. THIS WARRANTS CHC POPS FRI AFTN AND EVENING... HIGHEST ACROSS THE CAPE FEAR AREA. SHEAR PROFILES ARE UNIMPRESSIVE BOTH DAYS...BUT SOME DRY AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES SUGGEST THAT AN ISOLATED DAMAGING WIND GUST CANNOT BE RULED OUT. HIGH CAPE VALUES ENSURE THAT MOST STORMS WILL BE ACCOMPANIED BY NUMEROUS CLOUD-TO-GROUND LIGHTNING STRIKES AS WELL. THE WEAK COLD FRONT WILL PUSH THROUGH OUR CWA BY THE END OF THE PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE DESPITE THE BUILDING HEIGHTS ALOFT. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED. HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR FOG WITH LIGHT WINDS. EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 6:30 PM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: NO ADVISORIES OR CAUTION STATEMENTS WILL BE NEEDED FOR THE MARINE FORECAST THROUGH EARLY WEDNESDAY...WITH SW WINDS 15 KT OR LESS IN PLACE AND SEAS OF 2-3 FEET. SEAS ARE A MIX OF S WAVES 2 FT EVERY 4 SECONDS AND SE WAVES 1-1.5 FT EVERY 8-9 SECONDS. STEERING WINDS COULD GUIDE STORMS TOWARD THE SE OVER THE NEAR SHORE WATERS...AND GETTING A RADAR UPDATE BEFORE DISEMBARKING IS A GOOD IDEA THROUGH DAYBREAK WEDNESDAY. HEAVY RAIN COULD REDUCE VSBYS TO 1NM AT TIMES. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 315 PM WEDNESDAY...WINDS OVER THE WATERS WILL BE PRIMARILY SOUTHWEST THROUGH THE PERIOD...AOB 10 KTS ON THU BECOMING 10-15 KT BY FRI MORNING. 2 FT SEAS DURING THU WILL BUILD TO 2-3 FT OVERNIGHT THU AS THE GRADIENT TIGHTENS OFFSHORE. A BACKDOOR COLD FRONT WILL SLOWLY DROP SOUTHWARD ON FRI...CROSSING OUR WATERS NEAR THE END OF THE PERIOD. STRENGTHENING SOUTHWEST FLOW AHEAD OF THE FRONT DURING FRI WILL PRODUCE 3 FT SEAS. SEAS WILL SUBSIDE A BIT OVERNIGHT FRI AS WINDS BECOME NORTHWEST 5-10 KT FOLLOWING FROPA EARLY SAT MORNING. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...HEAT ADVISORY FROM NOON TO 6 PM EDT THURSDAY FOR SCZ023-032- 033-039-053>056. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...BJR NEAR TERM...MJC SHORT TERM...BJR LONG TERM...MBB AVIATION...MJC/DL MARINE...MJC/REK/MBB/BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
316 PM EDT WED AUG 20 2014 .SYNOPSIS... HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT COUPLE DAYS BEFORE SOME COOLING DURING THE WEEKEND AS A FRONT MOVES THROUGH. LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 315 PM WEDNESDAY...WARM H5 TEMPS OF -5 TO -6 ARE SQUELCHING THE PROPENSITY FOR TOWERS TO ASCEND VERY MUCH ABOVE 45000 FEET...BUT A SNAKE PIT OF SURFACE BOUNDARIES FROM OUTFLOWS...A SEA BREEZE LINE AND A STATIONARY FRONTAL BOUNDARY COULD BRIEFLY PULSE CELLS CLOSER TO SEVERE LIMITS IN ANY STRONG BOUNDARY COLLISION. PWAT VALUES REMAIN ELEVATED ACROSS NE SC/SE NC...ALONG WITH HIGH DEWPOINTS NEAR THE COAST AND AN APPROACHING UPPER TROUGH EVIDENT IN VAPOR MOVIES. THESE FEATURES MAY SUSTAIN CONVECTION THROUGH MUCH OF EVENING DESPITE A DIURNAL COOLING TREND AFTER DUSK. AT THE SFC A WEAK LOW PRESSURE AREA WILL RESIDE OVER INLAND ZONES AND SOME DEGREE OF LOW-LEVEL CONVERGENCE WILL REMAIN AVAILABLE AS WELL. LOCALIZED FLOODING APPEARS THE MAIN THREAT AT THIS TIME...THOUGH ANY COLLIDING BOUNDARIES COULD SET THE STAGE FOR STRONG WIND GUSTS ONCE THE ENSUING UPDRAFT COLLAPSES. DAYBREAK THURSDAY LOW/MID 70S MOST LOCATIONS WITH UPPER 70S TO NEAR 80 CLOSER TO THE IMMEDIATE COAST AND ICW LOCALS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 315 PM WEDNESDAY...THIS PERIOD WILL BE MARKED BY A RETURN OF SWELTERING HEAT AND HUMIDITY TO THE EASTERN CAROLINAS. AN UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE GULF COAST WILL EXPAND EASTWARD ON THU AS 500 MB HEIGHTS RISE OVER OUR CWA. 850 MB TEMPS CLIMB TO 19-20C ON THU AND 20-21C ON FRI AS NORTHWEST FLOW ALOFT RESULTS IN DOWNSLOPE ADIABATIC WARMING. EXPECT HIGHS ON THU/FRI TO REACH THE MID TO UPPER 90S EVERYWHERE AWAY FROM THE IMMEDIATE COAST. GIVEN THE LARGE VARIATIONS BETWEEN GFS/NAM DEWPOINTS ATTM...HAVE OPTED FOR A GMOS/NAM BLEND THAT GIVES DEWPOINTS IN THE LOW TO MID 70S. THIS YIELDS HEAT INDICES OF 100-105F ACROSS THE AREA BOTH DAYS. THE MOST OPPRESSIVE HEAT WILL BE FELT ACROSS NORTHEAST SOUTH CAROLINA...WHERE HEAT INDICES ARE EXPECTED TO EXCEED HEAT ADVISORY CRITERIA OF 105F. I WILL RAISE A HEAT ADVISORY FOR THU FOR ALL OF OUR SOUTH CAROLINA COUNTIES...EXCEPT DILLON AND MARLBORO COUNTY. CONDITIONS MAY WARRANT A HEAT ADVISORY FOR FRI AS WELL. UPPER RIDGING ON THU WILL WORK TO SUPPRESS CONVECTION DURING PEAK HEATING...AND THE LATEST GFS/NAM RUNS SHOW LITTLE TO NO ACTIVITY FOR US DURING THE DAY. WILL STILL MAINTAIN SLIGHT CHC POPS DURING THE AFTN HOURS AS MESOSCALE BOUNDARIES LIKE THE SEA BREEZE PROVIDE SOME ENHANCED LIFT. MOST ACTIVITY WILL BE DISPLACED NORTH OF OUR CWA ALONG WITH THE DEEPER MOISTURE. PWATS INCREASE TO AROUND 2.0 INCHES ON FRI AHEAD OF AN APPROACHING BACKDOOR COLD FRONT. AN UPPER DISTURBANCE EMBEDDED WITHIN THE NORTHWEST FLOW WILL ALSO MOVE OVERHEAD LATE FRI. THIS WARRANTS CHC POPS FRI AFTN AND EVENING... HIGHEST ACROSS THE CAPE FEAR AREA. SHEAR PROFILES ARE UNIMPRESSIVE BOTH DAYS...BUT SOME DRY AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES SUGGEST THAT AN ISOLATED DAMAGING WIND GUST CANNOT BE RULED OUT. HIGH CAPE VALUES ENSURE THAT MOST STORMS WILL BE ACCOMPANIED BY NUMEROUS CLOUD-TO-GROUND LIGHTNING STRIKES AS WELL. THE WEAK COLD FRONT WILL PUSH THROUGH OUR CWA BY THE END OF THE PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE DESPITE THE BUILDING HEIGHTS ALOFT. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED. HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR FOG WITH LIGHT WINDS. EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 315 PM WEDNESDAY...NO ADVISORIES OR CAUTION STATEMENTS WILL BE NEEDED FOR THE MARINE FORECAST THROUGH EARLY WEDNESDAY...WITH SW WINDS 15 KT OR LESS IN PLACE AND SEAS OF 2-3 FEET. SEAS ARE A MIX OF S WAVES 2 FT EVERY 4 SECONDS AND SE WAVES 1-1.5 FT EVERY 8-9 SECONDS. STEERING WINDS COULD GUIDE STORMS TOWARD THE SE OVER THE NEAR SHORE WATERS...AND GETTING A RADAR UPDATE BEFORE DISEMBARKING IS A GOOD IDEA THROUGH DAYBREAK WEDNESDAY. HEAVY RAIN COULD REDUCE VSBYS TO 1NM AT TIMES. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 315 PM WEDNESDAY...WINDS OVER THE WATERS WILL BE PRIMARILY SOUTHWEST THROUGH THE PERIOD...AOB 10 KTS ON THU BECOMING 10-15 KT BY FRI MORNING. 2 FT SEAS DURING THU WILL BUILD TO 2-3 FT OVERNIGHT THU AS THE GRADIENT TIGHTENS OFFSHORE. A BACKDOOR COLD FRONT WILL SLOWLY DROP SOUTHWARD ON FRI...CROSSING OUR WATERS NEAR THE END OF THE PERIOD. STRENGTHENING SOUTHWEST FLOW AHEAD OF THE FRONT DURING FRI WILL PRODUCE 3 FT SEAS. SEAS WILL SUBSIDE A BIT OVERNIGHT FRI AS WINDS BECOME NORTHWEST 5-10 KT FOLLOWING FROPA EARLY SAT MORNING. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...HEAT ADVISORY FROM NOON TO 6 PM EDT THURSDAY FOR SCZ023-032- 033-039-053>056. NC...NONE. MARINE...NONE. && $$ NEAR TERM...MJC SHORT TERM...BJR LONG TERM...MBB AVIATION...MJC/DL MARINE...MJC/BJR/MBB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT WED AUG 20 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW ALOFT WILL CROSS THE REGION THIS WEEK. A BACK DOOR COLD FRONT IS FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 220 PM WEDNESDAY... THE OVER ALL WEATHER PATTERN STILL CONSISTS OF RELATIVELY WEAK NORTHWESTERLY FLOW ALOFT AND A BROAD TROUGH AT THE SURFACE. ONE UPPER DISTURBANCE...ATTENDANT TO A SHORTWAVE CROSSING THE APPALACHIANS...CLIPPED THE NORTHERN HALF OF THE AREA THIS MORNING...BUT THE ASSOCIATED CONVECTION DIED AS IT MOVED INTO THE TRIAD. A TRAILING DISTURBANCE IS EVIDENT IN WATER VAPOR AND RAP H5 ANALYSIS OVER SOUTHWEST VA AND NORTHEAST TN...AND IS PROGGED TO CROSS THE AREA THIS EVENING. THE BEST INSTABILITY HAS DEVELOPED FROM THE SANDHILLS TO THE WESTERN PIEDMONT WHERE HEATING WAS UNINHIBITED BY MORNING STRATUS. WITHIN THE INSTABILITY AXIS...A ZONE OF LOW-LEVEL CONVERGENCE ACROSS THE SANDHILLS HAS INITIATED SOME SLOW MOVING SHOWERS AND ISOLATED STORMS FROM RAEFORD TO THE SOUTHEAST. THE APPROACHING DISTURBANCE SHOULD HELP TO INITIATE SOME ADDITIONAL CONVECTION THIS AFTERNOON...THOUGH THE HRRR HAS YET TO LATCH ONTO ANY TREND IN THE NEAR TERM. EXPECT SHOWERS AND STORMS ARE MORE LIKELY FROM THE TRIAD DOWN TO FAYETTEVILLE...WITH JUST A SLIGHT CHANCE FROM THO TRIANGLE NORTHEAST. IF CONVECTION DOES FIRE...A RIBBON OF 30KT EFFECTIVE DEEP SHEAR AT THE BASE OF THE UPPER TROUGH WILL SUPPORT SOME STRONGER CLUSTERS OF STORMS CAPABLE OF PRODUCING SMALL HAIL AND ISOLATED DAMAGING WIND GUSTS. TONIGHT...FORECAST SOUNDINGS SHOW SOME STEEP L;APSE RATES ABOVE THE NOCTURNAL INVERSION...BUT THERE ISNT A CLEAR MECHANISM TO FORCE ANY PARCELS OVERNIGHT...SO WILL LEAVE POPS OUT OF THE FORECAST AFTER 03Z. FORECAST SOUNDINGS ALSO SHOW LESS LOW-LEVEL MOISTENING TONIGHT WITHOUT THE NORTHEASTERLY FLOW WE`VE SEEN THE LAST COUPLE OF NIGHT...AND THEREFORE LESS POTENTIAL FOR STRATUS. LOWS IN THE UPPER 60S AND LOWER 70S. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 305 PM WEDNESDAY... MID-LEVEL RIDGING BUILDS OVER THE DEEP SOUTH ON THURSDAY...LEADING TO WEAK HEIGHT RISES OVER THE CAROLINAS AND H85 TEMPS SURPASSING 20C. FORECAST SOUNDINGS SHOW DEEP MIXING WITH WESTERLY FLOW...AND DRY ADIABATIC MIXING YIELDS HIGHS WILL INTO THE 90S...WITH A CONSENSUS OF 93-97. MIXING SHOULD ALSO HELP KNOCK DEWPOINTS BACK A FEW DEGREES...HELPING KEEP HEAT INDICES AT 100F OR LESS. MLCAPE OF AROUND 1000 J/KG IS FORECAST...BUT FORCING APPEARS TO BE LIMITED TO THE RESIDUAL/THERMAL TROUGH WHICH SETS UP OVER THE EASTERN PIEDMONT. WILL KEEP POPS AS ISOLATED UNLESS. LOWS THURSDAY NIGHT IN THE LOWER 70S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 145 PM WEDNESDAY... THE INITIAL LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER NORTHWEST UPPER FLOW INTO EARLY NEXT WEEK. A BACKDOOR FRONT WILL MOVE ACROSS THE AREA LATE FRIDAY THROUGH SATURDAY...WHICH WILL PRODUCE OUR BEST CHANCE OF PRECIPITATION DUE TO LOW LEVEL LIFT FROM THE COOL AIR ADVECTION POTENTIALLY AIDED BY MODEST UPPER LEVEL SUPPORT. OUTSIDE OF THE SLIGHTLY INCREASED CONFIDENCE IN THIS EARLY WEEKEND PERIOD... PRECIP CHANCES HINGE ON MESOSCALE DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW...WHICH ARE JUST ABOUT IMPOSSIBLE TO FORECAST THIS FAR IN ADVANCE. AS SUCH...WILL MAINTAIN SMALL CHANCE POPS THROUGH MONDAY...AFTER WHICH THE UPPER RIDGE AXIS SHIFTS EAST ENOUGH TO DAMPEN PRECIP CHANCES. HEIGHTS AND LOW LEVEL THICKNESSES PEAKING FRIDAY ARE INDICATIVE OF HIGHS REACHING THE MID 90S OVER MUCH OF THE AREA. THESE HEIGHTS FALL AS THE UPPER TROF DEEPENS ALONG THE EAST COAST CONCURRENT WITH COOL AIR ADVECTION BY LATER SATURDAY IN UNIFORM LOW LEVEL NORTHEAST FLOW. HIGHS WILL BE IN TRANSITION SATURDAY...FROM MID 80S NORTH TO 90 SOUTH...AND BOTTOMING OUT IN THE UPPER 70S TO LOWER 80S SUNDAY AND MONDAY AS DAMMING SETTLES DOWN THE EAST COAST. MORNING LOWS INITIALLY IN THE LOWER 70S SATURDAY MORNING WILL GRADUALLY FALL INTO THE LOW TO MID 60S BY TUESDAY MORNING. THE UPPER RIDGE AXIS WILL SHIFT EAST ON TUESDAY...WITH DRIER AIR AND GRADUAL MODIFICATION OF THE AIR MASS IN PLACE. HIGHS TUESDAY WILL BE MOSTLY IN THE LOW TO MID 80S...WARMING TO MOSTLY MID 80S ON WEDNESDAY. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 145 PM WEDNESDAY... MORNING STRATUS LIFTED TO VFR MOST PLACES PRIOR TO 17Z...THOUGH A FEW LOCATIONS ARE STILL REPORTING MVFR CEILINGS. INCREASING INSTABILITY AND AN APPROACHING WEAK UPPER DISTURBANCE SHOULD LEAD TO SCATTERED SHOWERS AND STORMS AGAIN THIS AFTERNOON...THOUGH THERE IS STILL NEAR TERM UNCERTAINTY AS TO WHERE SHOWERS AND STORMS WILL BE FOCUSED. BASED ON LATEST ANALYSIS IT APPEARS AREA FROM KGSO/KINT TO KFAY WILL BE MOST FAVORED...AND THERE ARE ALREADY SOME SHOWERS DEVELOPING JUST TO THE SOUTHWEST OF KFAY. OUTSIDE OF THE SHOWERS AND/OR STORMS...VFR CONDITIONS ARE EXPECTED TO PREVAIL. TONIGHT...LIGHT WINDS AND SOME CLEARING MAY LEAD TO LOW CLOUDS AND FOG BY THURSDAY MORNING...THOUGH FORECAST SOUNDINGS DONT SHOW AS MUCH POTENTIAL AS IN PREVIOUS NIGHTS. IF LOW CLOUDS OR FOG DEVELOP...IFR/LIFR CONDITIONS WOULD BE ANTICIPATED. OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...BLS SHORT TERM...BLS LONG TERM...MLM AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
220 PM EDT WED AUG 20 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW ALOFT WILL CROSS THE REGION THIS WEEK. A BACK DOOR COLD FRONT IS FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 220 PM WEDNESDAY... THE OVER ALL WEATHER PATTERN STILL CONSISTS OF RELATIVELY WEAK NORTHWESTERLY FLOW ALOFT AND A BROAD TROUGH AT THE SURFACE. ONE UPPER DISTURBANCE...ATTENDANT TO A SHORTWAVE CROSSING THE APPALACHIANS...CLIPPED THE NORTHERN HALF OF THE AREA THIS MORNING...BUT THE ASSOCIATED CONVECTION DIED AS IT MOVED INTO THE TRIAD. A TRAILING DISTURBANCE IS EVIDENT IN WATER VAPOR AND RAP H5 ANALYSIS OVER SOUTHWEST VA AND NORTHEAST TN...AND IS PROGGED TO CROSS THE AREA THIS EVENING. THE BEST INSTABILITY HAS DEVELOPED FROM THE SANDHILLS TO THE WESTERN PIEDMONT WHERE HEATING WAS UNINHIBITED BY MORNING STRATUS. WITHIN THE INSTABILITY AXIS...A ZONE OF LOW-LEVEL CONVERGENCE ACROSS THE SANDHILLS HAS INITIATED SOME SLOW MOVING SHOWERS AND ISOLATED STORMS FROM RAEFORD TO THE SOUTHEAST. THE APPROACHING DISTURBANCE SHOULD HELP TO INITIATE SOME ADDITIONAL CONVECTION THIS AFTERNOON...THOUGH THE HRRR HAS YET TO LATCH ONTO ANY TREND IN THE NEAR TERM. EXPECT SHOWERS AND STORMS ARE MORE LIKELY FROM THE TRIAD DOWN TO FAYETTEVILLE...WITH JUST A SLIGHT CHANCE FROM THO TRIANGLE NORTHEAST. IF CONVECTION DOES FIRE...A RIBBON OF 30KT EFFECTIVE DEEP SHEAR AT THE BASE OF THE UPPER TROUGH WILL SUPPORT SOME STRONGER CLUSTERS OF STORMS CAPABLE OF PRODUCING SMALL HAIL AND ISOLATED DAMAGING WIND GUSTS. TONIGHT...FORECAST SOUNDINGS SHOW SOME STEEP L;APSE RATES ABOVE THE NOCTURNAL INVERSION...BUT THERE ISNT A CLEAR MECHANISM TO FORCE ANY PARCELS OVERNIGHT...SO WILL LEAVE POPS OUT OF THE FORECAST AFTER 03Z. FORECAST SOUNDINGS ALSO SHOW LESS LOW-LEVEL MOISTENING TONIGHT WITHOUT THE NORTHEASTERLY FLOW WE`VE SEEN THE LAST COUPLE OF NIGHT...AND THEREFORE LESS POTENTIAL FOR STRATUS. LOWS IN THE UPPER 60S AND LOWER 70S. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 245 AM WEDNESDAY... LITTLE CHANGE ON THE SYNOPTIC PATTERN ON THURSDAY. CENTRAL NC WILL REMAIN POISED TO SEE VORT DISTURBANCES EMBEDDED IN THE NW FLOW ALOFT AS THE UPPER LOW OVER THE GREAT LAKES WEAKENS THROUGH THE DAY AS IT MOVES EAST INTO THE NE US. AT THIS TIME...CAN NOT FIND A DISCERNIBLE FEATURE THAT WOULD SUPPORT MORE THAN ISOLATED SLIGHT CHANCE POPS THURSDAY/THURSDAY NIGHT...IN FACT...500MB HEIGHTS ACTUALLY INCREASE OVER THE AREA ON THURSDAY...WITH ASSOCIATED SUBSIDENCE/WARMING ALOFT POSSIBLY SUPPRESSING CONVECTION TO A POINT WHERE IT COULD END UP BEING ONE OF THE LEAST CONVECTIVELY ACTIVE DAYS OF THE WEEK. AS FAR AS TEMPERATURES...BOTH THE EC AND GFS INDICATE H8 TEMPERATURES WILL WARM TO 22C...WHICH SHOULD SUPPORT HIGHS THURSDAY SOLIDLY IN THE MID 90S. LOWS THURSDAY NIGHT IN THE LOWER 70S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 145 PM WEDNESDAY... THE INITIAL LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER NORTHWEST UPPER FLOW INTO EARLY NEXT WEEK. A BACKDOOR FRONT WILL MOVE ACROSS THE AREA LATE FRIDAY THROUGH SATURDAY...WHICH WILL PRODUCE OUR BEST CHANCE OF PRECIPITATION DUE TO LOW LEVEL LIFT FROM THE COOL AIR ADVECTION POTENTIALLY AIDED BY MODEST UPPER LEVEL SUPPORT. OUTSIDE OF THE SLIGHTLY INCREASED CONFIDENCE IN THIS EARLY WEEKEND PERIOD... PRECIP CHANCES HINGE ON MESOSCALE DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW...WHICH ARE JUST ABOUT IMPOSSIBLE TO FORECAST THIS FAR IN ADVANCE. AS SUCH...WILL MAINTAIN SMALL CHANCE POPS THROUGH MONDAY...AFTER WHICH THE UPPER RIDGE AXIS SHIFTS EAST ENOUGH TO DAMPEN PRECIP CHANCES. HEIGHTS AND LOW LEVEL THICKNESSES PEAKING FRIDAY ARE INDICATIVE OF HIGHS REACHING THE MID 90S OVER MUCH OF THE AREA. THESE HEIGHTS FALL AS THE UPPER TROF DEEPENS ALONG THE EAST COAST CONCURRENT WITH COOL AIR ADVECTION BY LATER SATURDAY IN UNIFORM LOW LEVEL NORTHEAST FLOW. HIGHS WILL BE IN TRANSITION SATURDAY...FROM MID 80S NORTH TO 90 SOUTH...AND BOTTOMING OUT IN THE UPPER 70S TO LOWER 80S SUNDAY AND MONDAY AS DAMMING SETTLES DOWN THE EAST COAST. MORNING LOWS INITIALLY IN THE LOWER 70S SATURDAY MORNING WILL GRADUALLY FALL INTO THE LOW TO MID 60S BY TUESDAY MORNING. THE UPPER RIDGE AXIS WILL SHIFT EAST ON TUESDAY...WITH DRIER AIR AND GRADUAL MODIFICATION OF THE AIR MASS IN PLACE. HIGHS TUESDAY WILL BE MOSTLY IN THE LOW TO MID 80S...WARMING TO MOSTLY MID 80S ON WEDNESDAY. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 145 PM WEDNESDAY... MORNING STRATUS LIFTED TO VFR MOST PLACES PRIOR TO 17Z...THOUGH A FEW LOCATIONS ARE STILL REPORTING MVFR CEILINGS. INCREASING INSTABILITY AND AN APPROACHING WEAK UPPER DISTURBANCE SHOULD LEAD TO SCATTERED SHOWERS AND STORMS AGAIN THIS AFTERNOON...THOUGH THERE IS STILL NEAR TERM UNCERTAINTY AS TO WHERE SHOWERS AND STORMS WILL BE FOCUSED. BASED ON LATEST ANALYSIS IT APPEARS AREA FROM KGSO/KINT TO KFAY WILL BE MOST FAVORED...AND THERE ARE ALREADY SOME SHOWERS DEVELOPING JUST TO THE SOUTHWEST OF KFAY. OUTSIDE OF THE SHOWERS AND/OR STORMS...VFR CONDITIONS ARE EXPECTED TO PREVAIL. TONIGHT...LIGHT WINDS AND SOME CLEARING MAY LEAD TO LOW CLOUDS AND FOG BY THURSDAY MORNING...THOUGH FORECAST SOUNDINGS DONT SHOW AS MUCH POTENTIAL AS IN PREVIOUS NIGHTS. IF LOW CLOUDS OR FOG DEVELOP...IFR/LIFR CONDITIONS WOULD BE ANTICIPATED. OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...BLS SHORT TERM...CBL LONG TERM...MLM AVIATION...BLS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
136 PM EDT WED AUG 20 2014 .SYNOPSIS... HOT AND HUMID WEATHER WILL PREVAIL OVER THE NEXT SEVERAL DAYS BEFORE SOME COOLING DURING THE WEEKEND AS A FRONT MOVES THROUGH. LOCAL RAIN CHANCES WILL DECREASE EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. && .NEAR TERM /THROUGH TONIGHT/... AS OF 135 PM WEDNESDAY...UPDATED THE LAND FORECASTS TO INCREASE POP VALUES ACROSS THE WARNING AREA THROUGH THE AFTERNOON INTO EARLY EVENING BASED ON RADAR TRENDS. ORIENTATION OF A WIND CONVERGENCE BOUNDARY ALIGNED NEARLY ALONG THE PREVAILING STORM MOTION IS LEADING TO TRAINING OF CELLS IN BRUNSWICK COUNTY AND PORTIONS OF INLAND NC. FLOOD ADVISORIES WILL REMAIN POSSIBLE THROUGH EVENING DUE TO HIGH PWAT CONTENT AND POTENTIAL FOR TORRENTIAL EPISODES OF RAINFALL. THE PREVIOUS DISCUSSION FOLLOWS. HIGH PRECIPITABLE WATER CONTENT BETWEEN 1.75 AND 1.85 INCHES REMAINS LOADED IN THE COLUMN CURRENTLY AS REVEALED IN 12Z RAOBS DATA FROM MHX/CHS. THE POTENT UPPER SWIRL YESTERDAY THAT MOVED OFFSHORE LAST NIGHT...PUSHED A SURFACE TROUGH OVER THE COASTAL WATERS EARLIER THIS MORNING. NO APPRECIABLE AIR MASS CHANGE IN WAKE OF THIS FEATURE EXCEPT THAT DEWPOINTS REMAIN HIGHEST ALONG THE COAST WHILE TAPERING INLAND AND A LIGHT W-NW WIND ACROSS INLAND AREAS. SIMILAR TO MON/TUE...PLENTIFUL SUNSHINE WILL ENSURE LOW-LEVEL INSTABILITY WILL INCREASE INTO AFTERNOON IN A MOIST COLUMN. OF SOME CONCERN IS THAT PROJECTED STEERING WINDS WILL CARRY DEVELOPING AFTERNOON CONVECTION DIRECTLY PERPENDICULAR INTO A ROBUST SEA-BREEZE BOUNDARY. THE LOW-LEVEL WIND FLOW APPEARS POISED TO KEEP THIS MARINE BOUNDARY FASTENED CLOSE TO THE COAST...WHILE UPPER WINDS GUIDE ACTIVITY TO THE BEACHES AND COASTAL INTERIOR LATER TODAY. VAPOR ANALYSIS SHOWS SHORT-WAVE ENERGY IMPINGING THE SOUTHERN AND CENTRAL APPALACHIANS PRESENTLY...WHICH TIMING-WISE IS SET TO ENTER OUR NECK OF THE WOODS INTO OR JUST AFTER PEAK HEAT BUILD-UP...LIKELY SPARKING STORMS LATE AFTERNOON THROUGH EVENING. APPARENT TEMPS/HEAT INDICES AROUND 100 ACROSS NC AND 101-104 OVER OUR SC INTERIOR LOCATIONS TODAY. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM WEDNESDAY...THURSDAY WILL BRING UNSEASONABLE HEAT AND HUMIDITY. A LATE DAY SHORTWAVE PASSING BY TO OUR NORTH COULD FAVOR NORTHERN ZONES FOR SCATTERED CONVECTION WHILE ISOLATED CONVECTION EXPECTED ALON THE SEABREEZE IN SOUTH CAROLINA. THE PIEDMONT TROUGH WILL BE DISPLACED UNUSUALLY CLOSE TO THE COAST WHICH AND THIS SHOULD MINIMIZE CONVECTION CHANCES OVER INLAND ZONES. SHEAR AND MOISTURE PROFILES NOT INDICATIVE OF MUCH OF A SEVERE THREAT BUT STORMS WILL BE CAPABLE OF WET MICROBURSTS AS WELL AS SOME HIGH LIGHTNING RATES. STORMS MAY BE CLOSE BY TO OUR NORTH TOWARDS FRIDAY MORNING AS A BACKDOOR COLD FRONT APPROACHES. NORTHWESTERLY MID LEVEL FLOW STRENGTHENS ON FRIDAY AS THIS COLD FRONT CONTINUES ITS APPROACH. A NW FLOW SQUALL LINE OF FORCED CONVECTION APPEARS POSSIBLE IF NOT DOWNRIGHT INDICATED BY THE WRF. THE GFS IS SLOWER AND GENTLER WITH ITS DEPICTIONS OF THE UPPER VORT AS WELL AS SURFACE BOUNDARY ARRIVAL AND IS NOT AS SUGGESTIVE OF POSSIBLE STRONG STORMS ON FRIDAY. INTERESTINGLY BOTH MODELS` MOS STRINGS NOW SHOW FRIDAY AFTERNOON AS HOT IF NOT HOTTER THAN THURSDAY. FORECAST HAS BEEN ADJUSTED ACCORDINGLY. NOW BOTH AFTERNOONS MAY FEATURE A MAX HEAT INDEX OF AROUND 100 DEGREES OVER NRN ZONES TO 105 OR BETTER ALONG SC COASTAL ZONES WHERE THE WARMEST TEMPS AND HIGHEST DEWPOINTS ARE JUXTAPOSED. HEAT ADVISORY POSSIBLE FOR THOSE LATTER AREAS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 3 AM WEDNESDAY...THE WEEKEND WILL BRING AN EASING OF THE HEAT AND HUMIDITY AS THE FRONT STALLS NEAR THE REGION. THE WEATHER MAY STAY RATHER UNSETTLED THOUGH AS THE DEEP LAYER MOISTURE IS SLOW TO MAKE MUCH SOUTHERN PROGRESS. AS MID LEVEL RIDGE VERY SLOWLY CREEPS TOWARDS THE AREA FROM THE WEST MONDAY AND TUESDAY WE SHOULD SEE LESS DEEP MOISTURE AND THUS LOWER RAIN CHANCES. MEANWHILE THE HIGH STILL BUILDING IN FROM THE NORTH WILL KEEP TEMPERATURES RATHER SEASONABLE DESPITE THE BUILDING HEIGHTS ALOFT. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...ANOTHER SUMMER DAY...MORE CONVECTION EXPECTED. HOWEVER...LESS MOISTURE TO WORK WITH THAN THE PREVIOUS DAY. THE LEVEL OF FREE CONVECTION IS STILL FAIRLY HIGH...SO EXPECT CONVECTION TO FIRE LATE...AROUND 20Z LOOKS TO BE A GOOD BET. MOST OF IT WILL BE FOCUSED NEAR THE COAST...WITH ISOLATED ACTIVITY INLAND. WILL STICK WITH A TEMPO GROUP AS HRRR AND THE WRF MODEL DO HAVE DECENT COVERAGE THE THE COAST. WINDS WILL SHIFT TO THE SOUTHEAST THIS AFTERNOON WITH THE RESULTANT BOUNDARY. TONIGHT...MODERATE CONFIDENCE FOR PATCHY IFR FOG WITH LIGHT WINDS. EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 135 AM WEDNESDAY...WEAK MEANDERING BOUNDARY ACROSS THE NORTHERN PORTIONS OF THE ILM WATERS...WILL REVERT BACK TO NORTH OF THE WATERS THIS AFTN AND TONIGHT. WILL MAINLY HAVE TO DEAL WITH WIND DIRECTION CHANGES AS A RESULT...WITH OVERALL WIND SPEEDS 10 KT OR LESS DUE TO LACK OF ANY DECENT SFC PG. SIGNIFICANT SEAS WILL RUN UP TO 3 FT...AND MAINLY COMPRISED OF WIND DRIVEN WAVES AT 5 TO 6 SECOND PERIODS. AN UNDERLYING 1-2 FOOT PSEUDO GROUND SWELL AT 7+ SECOND PERIODS WILL CONTINUE THRU THIS PERIOD. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...PIEDMONT THROUGH WILL BE CLOSER TO THE COAST THAN NORMAL ON THURSDAY KEEPING THE GRADIENT ACROSS THE WATERS VERY LIGHT...CAPPED AT JUST 10 KTS WITH SOME INHERENT VARIABILITY POSSIBLE IN DIRECTION. NO REAL SWELL TO SPEAK OF SO SEAS SIMILARLY BENIGN AT JUST 2 FT OR LESS. LATE THURSDAY NIGHT INTO FRIDAY A FEW KNOTS OF WIND MAY BE ADDED AS A COLD FRONT APPROACHES FROM THE NW. NO APPRECIABLE INCREASE IN SEAS IS EXPECTED SAVE FOR A POSSIBLE APPEARANCE OF 3 FT SEAS OUT ALONG FRYING PAN SHOALS. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...COLD FRONT TO LAZILY MOVE SOUTH ACROSS THE ZONES ON SATURDAY. WIND SPEEDS WILL REMAIN VERY SLACK THROUGH FROPA SO AS WIND DIRECTION TURNS FROM OFFSHORE TO ONSHORE SEAS WILL LIKELY STAY AT THE 2 FT MARK OR LOWER. HIGH PRESSURE BUILDING IN FROM THE NORTH AND EAST ON SUNDAY WILL ADD 5 KT OF WIND FOR A HIGHER CATEGORY FORECAST. 3 FT SEAS SHOULD THUS RETURN TO MOST ZONES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...COLBY SHORT TERM...BACON LONG TERM...BACON AVIATION...DAVE/8
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1029 AM EDT WED AUG 20 2014 .SYNOPSIS... A WEAK COLD FRONT WILL CONTINUE TO MOVE THROUGH EASTERN NORTH CAROLINA THIS MORNING...THEN LIFT BACK NORTH ACROSS THE AREA LATE TODAY AND TONIGHT. THEN FRONT WILL LINGER THROUGH FRIDAY...THEN FINALLY PUSH THROUGH FRIDAY NIGHT INTO EARLY SATURDAY. HIGH PRESSURE WILL EXTEND SOUTH INTO THE REGION SUNDAY INTO MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1015 AM WED...LATEST SFC ANALYSIS SHOWS FRONTAL BOUNDARY SOUTH OF THE AREA IN THE VICINITY OF CAPE FEAR LATE THIS MORNING. WIDESPREAD FOG ACROSS THE AREAS THIS MORNING IS BURNING OFF QUICKLY PER VISIBLE SATELLITE AND EXPECT IT TO BE PRETTY MUCH DISSIPATED AROUND 15Z. ISOLATED SHOWERS PUSHING SOUTH ACROSS THE PAMLICO SOUND THAT WILL AFFECT DARE...HYDE AND TYRRELL COUNTIES FOR THE NEXT FEW HOURS. HRRR HAS THE SHOWERS SOUTH OF THE OBX AROUND 17Z...OTHERWISE LITTLE CHANGE TO FORECAST TODAY. THE FRONT WILL CONTINUE TO PUSH THROUGH THE VERY SOUTHERN CWA THIS MORNING...THEN LIKELY LIFT BACK NORTH THIS AFTERNOON INTO TONIGHT. COMBINED WITH A WEAK SHORTWAVE PIVOTING THROUGH THE UPPER LOW ACROSS THE GREAT LAKES PROVIDING UPPER LEVEL SUPPORT FOR CONVECTION. THE AIRMASS REMAINS UNSTABLE AND MOIST WITH PWATS AROUND 1.75-2" AND EXPECT ISOLATED TO SCATTERED CONVECTION TO DEVELOP THIS AFTERNOON. CONTINUED WITH SC/LOW CHANCE POPS. LOW LEVEL THICKNESS VALUES SUPPORT HIGHS IN THE MID 80S TO LOWER 90S. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... AS OF 715 AM WED...WEAK BOUNDARY WILL CONTINUE TO LIFT BACK INTO THE AREA TONIGHT THEN STALL. ANY EVENING CONVECTION SHOULD WANE WITH LOSS OF HEATING. THOUGH COULD SEE AN ISOLATED SHOWER/TSTM NEAR THE ALBEMARLE SOUND REGION OVERNIGHT ASSOCIATED WITH SHORTWAVE MOVING THROUGH THE MID-ATLANTIC REGION. AREAS OF FOG POSSIBLE AGAIN OVERNIGHT INTO EARLY THURSDAY MORNING. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 230 AM WED...LOW LEVEL WSW FLOW IN COMBINATION WITH DEVELOPING WNW FLOW PATTERN ALOFT AND RISING THICKNESSES WILL SET UP VERY WARM CONDITIONS EARLY IN THE FORECAST PERIOD. HIGHS THURSDAY WILL REACH LOW TO POSSIBLY MID 90S INLAND WITH UPPER 80S AT THE BEACHES, WITH HEAT INDICES AROUND 100 INLAND. RELATIVE LACK OF FORCING SHUD LIMIT PRECIP CHANCES THRU EARLY THU AFTN BUT LINGERING WEAK SFC BNDRY AND SUBTLE SHORT WAVE ENERGY IN THE UPPER FLOW MAY HELP TRIGGER A FEW TSTORMS LATE IN THE AFTN. UPPER TROF WILL DEEPEN OFF THE COAST LATE IN THE WEEK AND MOVE ONLY SLOWLY FARTHER OFFSHORE THIS WEEKEND AND EARLY NEXT WEEK AS BLOCKY PATTERN SETS WITH STRONG UPPER RIDGE BUILDING OVER THE MISSISSIPPI VALLEY REGION. THIS DEVELOPING UPPER PATTERN WILL PLACE EASTERN NC IN PERSISTENT NNW FLOW ALOFT AND SHORT WAVES MOVING THRU THE FLOW WILL TRIGGER OCCASIONAL BOUTS OF PRECIPITATION THU NIGHT THRU SAT. THIS PATTERN MAY ALSO FAVOR MCS DEVELOPMENT...HOWEVER TIMING THESE SMALL SCALE SYSTEMS IN THE LONGER TERM WILL BE DIFFICULT. HAVE KEPT CHANCE POPS IN THRU SAT. HIGH PRES WILL BUILD IN FROM THE N SUN AND MON AND CONT INTO TUE WITH SOMEWHAT DRIER AIR AND LIMIT THREAT FOR PRECIP...ESPCLY MON AND TUE. HIGHS WILL AGAIN REACH LOWER 90S INLAND FRI THEN WITH NE FLOW SAT INTO EARLY NEXT WEEK EXPECT HIGHS MAINLY LOW TO MID 80S. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH TONIGHT/... AS OF 1015 AM WED...WIDESPREAD FOG ACROSS RTES THIS MORNING IS BURNING OFF QUICKLY THIS MORNING PER VISIBLE SATELLITE AND EXPECT IT TO BE DISSIPATED BY 15Z OR SHORTLY AFTERWARD WITH PRED VFR RETURNING. ISOLATED/SCATTERED CONVECTION EXPECTED AGAIN THIS AFTERNOON AND EVENING. AREAS OF FOG POSSIBLE AGAIN OVERNIGHT AND EARLY THURSDAY MORNING. LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 230 AM WED...SOME FOG/ST WILL BE POSS EARLY THU MORN THEN MAINLY VFR REST OF DAY WITH SOME WIDELY SCT TO SCT CONVECTION POSS LATE. BOUTS OF SHRA AND TSRA EXPECTED THU NIGHT THRU SAT WITH SHORT WAVES MOVING ACROSS IN NW FLOW ALOFT. THERE WILL LIKELY BE SOME BRIEF PDS OF REDUCED CIGS/VSBYS WHEN SHRA/TSRA CROSS OTHERWISE MOSTLY VFR EXPECTED. PRECIP CVRG EXPECTED TO DIMINISH A BIT SUNDAY AS HIGH PRES AND A LITTLE DRIER AIR PUSHES IN FROM THE N...SHLD BE MAINLY VFR. && .MARINE... SHORT TERM /THROUGH TONIGHT/... AS OF 715 AM WED...WEAK FRONTAL BOUNDARY CONTINUES TO PUSH THROUGH THE VERY SOUTHERN WATERS THIS MORNING...IT WILL THEN LIKELY LIFT BACK NORTH THIS AFTERNOON INTO TONIGHT. LATEST OBS SHOW NW/NE WINDS 5-15KT AND SEAS 2-4FT. WINDS LESS THAN 15KT EXPECTED TODAY...THEN LESS THAN 10KT TONIGHT WITH SEAS 2-3FT. WIND DIRECTIONS HOWEVER WILL BE CHALLENGING TODAY ESP SOUTH OF LOOKOUT. LIKELY N/NW BEHIND THE BOUNDARY EARLY THEN BACKING BECOMING SW THIS AFTERNOON AND TONIGHT. NORTH OF LOOKOUT MAINLY N/NE TODAY BECOMING E/NE TONIGHT. LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 230 AM WED...LIGHT AND VARIABLE WINDS THU MORN WILL BECOME S AOB 10 KTS THU AFTN. SW WINDS EXPECTED 10 TO 15 KTS THU NIGHT AHEAD OF APPROACHING FRONT. COLD FRONT WILL SLOWLY PUSH S ACROSS THE WTRS FRI AND FRI NIGHT WITH WINDS BECOMING N/NE IN ITS WAKE WITH SPEEDS MAINLY BELOW 15 KTS. NE WINDS EXPECTED OVER THE WEEKEND AS HIGH PRES BUILDS IN FROM THE N WITH WEAK LOW WELL OFF THE CST. ECMWF HAS TIGHTER GRDNT WITH DEEPER LOW OFF THE CST AND SHOWS WINDS NEAR 20 KTS...FOR NOW LEANED CLOSER TO GFS WITH SPEEDS MAINLY 10 TO 15 KTS. SEAS WILL BE MAINLY 2 TO 3 FEET THU THRU SAT MORN. AS NE FLOW GRAD INCREASE LATER SAT AND SUN WILL HAVE 4 FOOT SEAS DEVELOP OUTER WTRS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RF/CQD NEAR TERM...SK/CQD SHORT TERM...CQD LONG TERM...BTC/RF AVIATION...RF/SK/CQD MARINE...RF/CQD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
122 AM CDT WED AUG 20 2014 .UPDATE... ISSUED AT 103 AM CDT WED AUG 20 2014 THE MAIN FOCUS THIS MORNING IS ON PRECIPITATION AMOUNTS AND THE FLOOD RISK. THE 00 UTC HIRES ARW AND WRF AND HRRR ARE IN GOOD AGREEMENT THAT THE PREVIOUS FORECAST IS TOO FAST WITH THE ONSET OF CONVECTION. THERE HAS ALSO BEEN A TREND TOWARD PUSHING CONVECTION FURTHER NORTH...WHICH WOULD SPARE MUCH OF THE SOUTHWEST FROM HEAVIER AMOUNTS. DECISIONS WILL NEED TO BE MADE THIS MORNING REGARDING ANY FLOOD OR FLASH FLOOD WATCHES. UPDATE ISSUED AT 953 PM CDT TUE AUG 19 2014 A FEW MINOR ADJUSTMENTS TO SKY COVER FOR THE LATE EVENING UPDATE. LATEST RADAR IMAGERY SHOWS ISOLATED CONVECTION LIFTING THROUGH SOUTH CENTRAL MONTANA...WHICH SHOULD MOVE INTO NORTH DAKOTA LATE TONIGHT. THIS IS CURRENTLY HANDLED WELL. ALSO WEAK CONVECTION CONTINUES TO FIRE OVER FAR NORTHEAST MONTANA INTO SOUTHERN SASKATCHEWAN. MODELS DO SHOW AN INCREASING JET OVER WESTERN NORTH DAKOTA TONIGHT IN AN AREA OF WEAK UPPER LEVEL DIVERGENCE AND INSTABILITY ALOFT. COULD POSSIBLY BE SOME ELEVATED CONVECTION ACROSS THE NORTHWEST INTO THE NORTH CENTRAL LATE TONIGHT SO EXTENDED SOME SLIGHT POPS EAST ACROSS THESE AREAS AFTER MIDNIGHT. UPDATE ISSUED AT 639 PM CDT TUE AUG 19 2014 A COUPLE OF THUNDERSTORMS DEVELOPED OVER SOUTHWEST NORTH DAKOTA LATE THIS AFTERNOON IN AN AREA OF CAPES AROUND 2000 J/KG AND 25-35 KNOTS OF BULK SHEAR. ONE HAS DISSIPATED AS IT MOVED FROM BOWMAN INTO ADAMS COUNTY. THE SECOND IS STILL HOLDING TOGETHER OVER CENTRAL SLOPE. WILL MAINTAIN OUR SLIGHT CHANCE POPS OVER THE SOUTHWEST. A FEW CELLS TRIED TO FIRE OVER THE NORTHWEST BUT WITH LESS LUCK IN A LOW SHEAR ENVIRONMENT. SCATTERED CONVECTION OVER NORTHEAST MONTANA CONTINUES TO LIFT NORTHEAST BUT IS HAVING A HARD TIME MAINTAINING ITS STRENGTH AS IT APPROACHES NORTHWEST NORTH DAKOTA. WILL HOLD OFF ON BRINGING ANY SLIGHT CHANCE POPS INTO THE FAR NORTHWEST. OTHERWISE QUIET ACROSS MOST OF WESTERN AND CENTRAL NORTH DAKOTA WITH NO CHANGES NEEDED TO THE GOING FORECAST. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 327 PM CDT TUE AUG 19 2014 THE MAIN CONCERN IN THE SHORT TERM FORECAST PERIOD IS EXPECTED WIDESPREAD SHOWERS AND THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT. THE PROBLEM IS LOW CONFIDENCE ON WHERE THE HEAVIEST RAINFALL TOTALS CAN BE EXPECTED. CURRENTLY...SURFACE LOW PRESSURE WAS OVER SOUTHWESTERN SASKATCHEWAN AND NORTH CENTRAL MONTANA AHEAD OF AN UPPER LEVEL LOW/TROUGH OVER UTAH. SURFACE DEWPOINTS WERE IN THE MID 50S WEST AND IN THE 60S OVER EASTERN NORTH DAKOTA. TONIGHT THE UPPER LOW LIFTS NORTHEASTWARD AND APPROACHES SOUTHWESTERN NORTH DAKOTA. IN RESPONSE...THE SURFACE LOW/TROUGH SHOULD DEVELOP EASTWARD SO THAT BY DAYBREAK WEDNESDAY IT IS ALONG THE MONTANA/DAKOTAS BORDER. SOME MODELS ARE DEPICTING SOME ISOLATED SHOWERS/THUNDER BEFORE DAYBREAK IN THE WEST...AND HAVE KEPT ISOLATED/SMALL CHANCE PROBABILITIES FOR THE WESTERN QUARTER OF THE STATE THROUGH DAYBREAK. MODELS ARE IN GOOD AGREEMENT THAT SHORTLY AFTER/AT DAYBREAK THE UPPER LEVEL ENERGY IMPULSES WILL BE SUFFICIENT FOR INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE DAYLIGHT MORNING HOURS. AROUND/AFTER NOON SHOWERS AND THUNDERSTORMS SHOULD BE WIDESPREAD AND NUMEROUS ACROSS WESTERN AND CENTRAL NORTH DAKOTA. WEDNESDAY EVENING MOST OF THE PRECIPITATION FROM THE THUNDERSTORMS SHOULD BE IMPACTING ALL BUT THE FAR WESTERN PORTION OF NORTH DAKOTA...WITH DECREASING CHANCES FROM WEST TO EAST LATE WEDNESDAY NIGHT. THE MAIN PROBLEM IS THAT THE VARIOUS MODELS ARE NOT COMING TO A GOOD CONSENSUS REGARDING PLACEMENT OF THE HEAVIEST PRECIPITATION. THE NAM MODEL IS FARTHEST NORTH WITH THE PLACEMENT OF HEAVY PRECIPITATION...WITH WESTERN AND NORTH CENTRAL NORTH DAKOTA (SOURIS RIVER BASIN) TAKING THE BIGGEST HIT. THE GFS/ECMWF WANT TO SPLIT THE ENERGY - AND HENCE RESULTING IN TWO HEAVIER PRECIP BULLS-EYES - WITH ONE OVER THE SOURIS BASIN...AND ANOTHER OVER CENTRAL NORTH DAKOTA. THE OTHER SHORT TERM HIGH RESOLUTION MODELS ARE FAVORING SOUTH CENTRAL NORTH DAKOTA. FINAL PRECIPITATION FORECAST INVOLVES A SECTION OF SOUTH CENTRAL NORTH DAKOTA INCLUDING THE JAMES RIVER VALLEY OF 1 TO 1.5 INCHES OF RAIN...AND AROUND 0.75 TO 1 INCH OVER THE NORTHWEST/NORTH CENTRAL. A HYDROLOGIC OUTLOOK (ESF) HAS BEEN ISSUED TO ADDRESS THIS FIRST WAVE OF PRECIPITATION WEDNESDAY THROUGH WEDNESDAY NIGHT...THEN ALSO ADDRESSES THE LONG TERM PERIOD EXPECTED PRECIPITATION THURSDAY NIGHT THROUGH THE WEEKEND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 327 PM CDT TUE AUG 19 2014 A VERY ACTIVE/WET PATTERN THROUGH THE WEEKEND WILL HIGHLIGHT THE EXTENDED FORECAST PERIOD. WILL NOTE 12Z MODELS STILL SHOW CONSIDERABLE SPREAD IN REGARDS TO PRECIPITATION...TIMING/PLACEMENT/AMOUNTS...FRIDAY NIGHT THROUGH SUNDAY. BETTER AGREEMENT THURSDAY THROUGH FRIDAY. FOR THURSDAY...SHOWERS/THUNDERSTORMS WILL BE IN THE PROCESS OF LIFTING OFF TO OUR NORTHEAST DURING THE MORNING AS A MID LEVEL S/WV IMPULSE EJECTS INTO CANADA AND ITS ASSOCIATED SFC TROUGH PUSHES EAST INTO THE UPPER MISSISSIPPI VALLEY. CONVECTIVE REDEVELOPMENT WILL BE VERY POSSIBLE THURSDAY AFTERNOON/EVENING AS WE REMAIN IN SOUTHWESTERLY FLOW ALOFT ALONG WITH AMPLE INSTABILITY AND DECREASING CIN AS THE DAY PROGRESSES. MAIN AREA OF PRECIPITATION WILL ENTER WESTERN NORTH DAKOTA THURSDAY NIGHT AS ANOTHER EMBEDDED WAVE LIFTS NORTHEAST ACROSS EASTERN MONTANA INTO FAR SOUTH CENTRAL CANADA...ALONG WITH FORCING ASSOCIATED WITH THE UPPER LEVEL JET NOSING INTO THE REGION RESULTING IN DIVERGENCE ALOFT OVERSPREADING THE NORTHERN PLAINS. BASED ON THE PROJECTED TRACK OF THE MID LEVEL S/WV DEPICTED BY BOTH THE 12Z GFS/ECMWF...MOST FAVORABLE AREAS FOR HEAVY PRECIPITATION WILL BE OVER THE WESTERN HALF OF THE STATE AND INTO THE NORTH CENTRAL THURS NIGHT-FRIDAY MORNING. UPPER LEVEL TROUGH DIGS ACROSS THE WESTERN CONUS FRIDAY-SATURDAY...THEN LIFTS NORTH AND EAST ACROSS THE DAKOTAS SAT NIGHT-SUN NIGHT. MODEL SPREADS RATHER HIGH IN REGARDS TO PRECIPITATION DURING THE FRIDAY/SATURDAY TIMEFRAME...WITH LEAD S/WV IMPULSES DIFFICULT FOR MODELS TO KEY IN ON AT THIS TIME. SOME LOCATION DIFFERENCES AS WELL SAT NIGHT INTO SUNDAY WITH THE TRACK OF THE MAIN UPPER LEVEL WAVE WHEN IT MOVES ACROSS THE LOCAL REGION. LOOKS TO BE WET MOST LOCATIONS. WE REMAIN IN A QUASI-ACTIVE FLOW PATTERN INTO EARLY NEXT WEEK AS WELL WITH A BROAD TROUGH IN PLACE ALOFT MONDAY AND TUESDAY. TEMPERATURES WILL COOL SIGNIFICANTLY FROM FRIDAY INTO SUNDAY WITH THE PRECIPITATION EXPECTED AND STRONG CAA ON SUNDAY IN THE WAKE OF A STRONG SURFACE LOW AND UNDERNEATH THE UPPER WAVE. HIGHS SUNDAY WILL BE IN THE 60S COMPARED TO UPPER 70S AND MID 80S ON THURSDAY. A SLIGHT MODERATION IN HIGHS FORECAST NEXT WEEK MONDAY AND TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 103 AM CDT WED AUG 20 2014 THUNDERSTORMS WILL INCREASE FROM WEST TO EAST TODAY. THERE IS HIGH UNCERTAINTY ON TIMING AND PLACEMENT BEYOND THAT TREND...SO THE TIMING IN TAFS IS A BEST GUESS. THERE COULD BE MVFR VISIBILITIES AND CEILINGS WITH STRONGER THUNDERSTORMS. && .HYDROLOGY... ISSUED AT 327 PM CDT TUE AUG 19 2014 THERE WILL BE POTENTIALLY SIGNIFICANT RAINS ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA FROM WEDNESDAY MORNING THROUGH EARLY THURSDAY...AND THEN AGAIN THURSDAY NIGHT THROUGH SUNDAY. THOSE AREAS OF THE STATE WHICH RECEIVE MULTIPLE PASSES OF HEAVY RAINS OF HEAVY RAIN WILL LIKELY EXPERIENCE EXCESSIVE RUNOFF AND A HIGHER LIKELIHOOD OF OVERLAND AND SMALL STREAM FLOODING. WHILE THE SOURIS RIVER BASIN OF NORTH DAKOTA HAS BEEN RELATIVELY DRY TO NEAR NORMAL THE PAST FEW WEEKS...SOME OF THE MODELS DEPICT WIDESPREAD RAINS BETWEEN TWO AND FOUR INCHES ACROSS THE UPPER PORTIONS OF THE SOURIS IN NORTH DAKOTA AND SASKATCHEWAN. AREAS THAT RECEIVE AN INITIAL WETTING DURING THE EARLIER EVENT ARE MORE LIKELY TO EXPERIENCE EXCESSIVE RUNOFF DURING THE LATTER RAINS. SEVERAL MISSOURI RIVER TRIBUTARIES WERE PARTICULARLY HARD HIT BY HEAVY RAINS LAST WEEKEND, INCLUDING THE KNIFE AND HEART RIVERS ALONG WITH APPLE CREEK. THESE RIVERS WILL STILL BE RUNNING WELL ABOVE NORMAL AS THE NEXT FEW WEATHER SYSTEMS MOVE INTO THE STATE. THE JAMES AND PIPESTEM CREEK BASINS HAVE NOT BEEN PARTICULARLY AFFECTED BY RECENT HEAVY RAINS. HOWEVER...THERE HAS BEEN ENOUGH RAIN TO KEEP THE SOIL MOISTURE LEVELS AT OR ABOVE NORMAL FOR THIS TIME OF YEAR. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SCHECK SHORT TERM...JV LONG TERM...NH AVIATION...SCHECK HYDROLOGY...AJS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
417 PM EDT WED AUG 20 2014 .SYNOPSIS... A FRONTAL ZONE WILL SETTLE INTO THE OHIO VALLEY THIS EVENING. THIS FRONT WILL GRADUALLY LIFT NORTHEAST INTO THE GREAT LAKES THROUGH THE WEEKEND. DISTURBANCES WILL INTERACT WITH A MOIST AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS AT TIMES THROUGH THE PERIOD. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... CONVECTION THAT IS AFFECTING THE TRI-STATE REGION ATTM WASNT HANDLED WELL BY THE MODELS. THE HRRR HAS TRIED TO DISSIPATE ALL AFTERNOON. KEPT THE CONVECTION TOGETHER AND PUSHED IT THRU THE OHIO RIVER COUNTIES LATE THIS AFTERNOON. FIGURING OUT POPS FOR THE REST OF THE NIGHT IS TOUGH....SINCE THE MODEL GUIDANCE DIDNT COVER THIS CURRENT CONVECTION WELL. THAT MAKES IT HARD TO FIGURE OUT WHEN TO TRANSITION FROM THE RADAR TO MODEL. DEVELOPED SOME PCPN IN THE TRI- STATE REGION BETWEEN 00-06Z ALONG A WEAK FRONT. THIS IS SIMILAR TO THE CMC/NAM SOLUTION. THEN LET IT DISSIPATE AS FOCUS SHIFTS TO ENERGY TO OUR NW. LOWS TONIGHT WILL BE WARM AND MUGGY. TEMPERATURES WILL ONLY DROP INTO THE UPPER 60S TO LOWER 70S. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... THERE IS A LARGE VARIATION IN MODEL SOLUTIONS FOR THURSDAY. PREFER A NAM/CMC REGIONAL/HIRES-WRF SOLUTION WHICH DROPS H5 ENERGY INTO THE REGION EARLY THURSDAY MORNING IN THE NW FLOW. THEY PUSH THE BEST PCPN CHANCE ACROSS THE REGION DURING THE MORNING...AND EXIT IT OUT OF THE EAST DURING THE AFTN. THURSDAY NIGHT BETTER FORCING SHIFTS TO NRN OHIO AS CONVERGENCE ALONG A LIFTING WARM FRONT MOVES ALSO. PUT HIGH CHANCE POPS IN THE NORTHERN COUNTIES WITH DECREASING POPS DOWN TO THE SW. ON FRIDAY...ADDITIONAL H5 ENERGY TOPS THE RIDGE AND DROPS SE ACROSS THE REGION. THIS WILL HELP DEVELOP DAYTIME CONVECTION...BUT CENTRAL OHIO WILL HAVE THE BEST CHANCE AT SEEING CONVECTION AS IT IS CLOSER TO THE WARM FRONT. CONVECTION TOMORROW WILL COMPLICATE THE HIGH TEMPERATURE FORECAST. ONLY WENT LOWER 80S IN THE NW COUNTIES SINCE THE CONVECTION SHOULD LIMIT HEATING THERE. SOUTHERN COUNTIES SHOULD BE ABLE TO MAKE THE MID TO UPPER 80S. AFTER DROPPING DOWN TO ONLY AROUND 70 THURSDAY NIGHT...FRIDAY IS LOOKING LIKE A HOT AND HUMID DAY. OHIO RIVER COUNTIES SHOULD SEE TEMPERATURES PUSH INTO THE LOWER 90S WITH DEWPOINTS IN THE LOWER 70S. THIS WILL PUSH HEAT INDICES OVER 100. WILL CONTINUE TO HIGHLIGHT THE THREAT IN THE HWO. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AT 12Z ON SATURDAY...THE 20.12Z ECMWF AND GFS ARE VERY GOOD AGREEMENT ON THE LARGE SCALE PATTERN WITH AN AMPLIFIED FLOW PATTERN OVER THE LOWER 48. A DEEP CLOSED LOW SHOULD BE OVER ID/MT WITH A STRONG SUBTROPICAL RIDGE EXTENDING NORTHEAST FROM A 593DM HIGH OVER ALABAMA. ANOMALOUS MOISTURE WILL STILL BE IN PLACE WITH PWAT FROM 1.5 TO 2.0 STANDARD DEVIATIONS ABOVE CLIMO. THROUGH THE WEEKEND THE STRONG CLOSED LOW WILL SWING NORTHEAST INTO THE NRN HIGH PLAINS AND EVENTUALLY INTO SASK...WHILE THE RIDGE EXPANDS NORTHEASTWARD INTO TN/ARK. DESPITE WEAK FORCING...CONTINUED NORTHERLY/NORTHWESTERLY FLOW AROUND THE RIDGE...THE PRESENCE OF A WEAK SURFACE TROUGH...AND ANOMALOUS MOISTURE SHOULD CONTINUE TO ALLOW FOR STRONG DAYTIME INSTBY BOTH SAT AND SUN. THE POTENTIAL FOR ONE MORE CLUSTERS OF SSE PROPAGATING STORM CLUSTERS WILL CONTINUE THROUGH THE WEEKEND. GIVEN THE MAGNITUDE OF INSTBY...EVEN WITH WEAKENING FLOW WITH TIME...THERE COULD BE STRONG/SEVERE STORM THREAT ON EITHER OF THESE DAYS IF A ORGANIZED COLD POOL COULD FORM. GETTING INTO MONDAY-TUESDAY...THE RIDGE CONTINUES TO BUILD WITH HEAT/HUMIDITY. FLOW BECOMES VERY LIGHT THROUGH THE BULK OF THE TROPOSPHERE AND IT BECOMES QUESTIONABLE IF COVERAGE OF DAYTIME/EVE STORMS WARRANTS MENTION. RIGHT NOW HAVE RUN 15-25% RAIN CHANCES BOTH OF THESE DAYS...AND THAT MAY BE TOO HIGH. INTO WEDNESDAY...SOME HINTS OF HEIGHT FALLS WHICH MAY ALLOW A LITTLE STRONGER FLOW OR A WEAK SHORTWAVE TROUGH TO CROSS THE GREAT LAKES. SO A BETTER STORM THREAT THEN...HOWEVER AT THIS TIME RANGE THIS IS A VERY LOW CONFIDENCE FORECAST GIVEN CONDITIONAL NATURE OF THE RIDGE BUCKLING. SO ALL IN ALL...HAVE TENDED TO FOCUS RAIN CHANCES NEAR PEAK HEATING INTO THE EVENING AND ALLOW FOR SOME DRY NIGHTS/EARLY MORNINGS. FLY IN OINTMENT WILL BE ANY FORWARD PROPAGATING MCS THAT SURVIVES THROUGH THE NIGHT...ORIGINATING TO OUR NORTHWEST AND FALLING DOWN NNWLY FLOW EITHER SATURDAY MORNING OR SUNDAY MORNING. LOW CONFIDENCE STORM CHANCE...BUT HIGH CONFIDENCE WARM/HUMID PATTERN IS THE STORY FOR THE SAT-WED TIMEFRAME. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... CONVECTION TO THE WEST OF THE AREA IS EXPECTED TO WEAKEN BEFORE REACHING THE CINCINNATI TERMINALS. THERE WILL BE A LOT OF LEFT OVER CLOUDS ALTHOUGH THEY ARE EXPECTED TO BE VFR. ELSEWHERE SCATTERED CUMULUS WILL DISSIPATE WITH LOSS OF HEATING. QUITE A BIT OF UNCERTAINTY REGARDING POTENTIAL FOR THUNDERSTORMS DURING THE LATTER HALF OF THE FORECAST PERIOD. APPEARS THAT STORMS COULD START TO DEVELOP AFTER 06Z. ONCE STORMS DO DEVELOP THERE COULD BE REPEATED ACTIVITY OVER THE SAME AREA BEFORE A LULL OCCURS LATE IN THE FORECAST PERIOD. OUTLOOK...THUNDERSTORMS POSSIBLE THURSDAY AFTERNOON THROUGH SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...SITES/SNYDER NEAR TERM...SITES SHORT TERM...SITES LONG TERM...BINAU AVIATION...
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
224 AM EDT WED AUG 20 2014 .SYNOPSIS... LOW PRESSURE OVER LAKE MICHIGAN WILL SLOWLY MOVE TO THE EASTERN GREAT LAKES THROUGH THURSDAY...PUSHING A WEAK COLD FRONT SOUTH ACROSS THE AREA. HIGH PRESSURE WILL BUILD OVER LAKE ERIE BEHIND THIS SYSTEM THURSDAY NIGHT...SHIFTING TO THE EASTERN GREAT LAKES ON FRIDAY. A WARM FRONT WILL LIFT NORTH ACROSS THE AREA ON FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MAIN LINE OF SHOWERS AND THUNDERSTORMS MOVED EAST THROUGH THE AREA WITH SOME POCKETS OF MORE ACTIVITY MOVING EAST INTO THE REGION AT THIS TIME. ANOTHER LINE IS TRYING TO GET ORGANIZED OVER WESTERN OHIO. POTENTIAL EXISTS THAT SOUTHERN PART OF THE LINE WILL TRY TO FILL IN. NORTHERN PART IS NOT AS PROMISING. ALONG THIS LINE IS AN AREA OF CONVERGENCE AND SOME INSTABILITY TO SUPPORT THE ACTIVITY AS IT MOVES EAST. LATEST NAM OUTPUT SHOWS THIS AREA OF CONVERGENCE MOVING HALFWAY EAST ACROSS THE FORECAST AREA BEFORE THE CONVERGENCE WEAKENS WITH TIME. HOWEVER...LATEST HRRR MODEL DOES SHOW THE WEAKENING A BIT ACROSS THE CENTRAL PORTIONS AND THEN NEW DEVELOPMENT TAKES PLACE ALONG THE OUTFLOW BOUNDARY FURTHER EAST. MINOR ADJUSTMENTS TO TEMPERATURES WITH THIS UPDATE. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... NEARLY VERTICALLY STACKED UPPER LEVEL AND SURFACE LOW WILL BE OVER THE CENTRAL GREAT LAKES ON WEDNESDAY. A MOIST AND UNSTABLE AIR MASS WILL RESIDE WITHIN THE AREA OF SOUTHERLY FLOW AHEAD OF THE SURFACE LOW ACROSS MAINLY NE OHIO AND NW PA. CAPES ARE EXPECTED TO INCREASE TO AROUND 2500 J/KG WITH SEVERAL MECHANISMS FOR CONVECTIVE INITIATION DURING THE AFTERNOON. STORMS WILL FIRE DURING THE AFTERNOON AS THE LOW SLOWLY MOVES EASTWARD. HIGHER RESOLUTION MODELS ALSO SHOW SOME CONVERGENCE DOWNWIND OF LAKE ERIE THAT WILL SET UP SOUTH OF I-90. LARGE SCALE FORCING WILL ALSO INCREASE DURING THE LATE AFTERNOON AS A 35 KNOT MID-LEVEL JET STREAK MOVES THROUGH THE NORTHWESTERLY FLOW ON THE BACK SIDE OF THE TROUGH. ALL OF THIS COMBINES TO MAKE THUNDERSTORMS LIKELY ON THURSDAY ACROSS AT LEAST THE EASTERN HALF OF THE FORECAST AREA. LESS CERTAIN IS IF ANYTHING CAN FIRE ACROSS NW OHIO AHEAD OF THE JET STREAK WHICH CAN NOT BE ENTIRELY RULED OUT SO WILL LEAVE A LOW POP IN THE NW OHIO. WHATEVER BREAKS EXIST IN THE CLOUDS TO START THE DAY IN NE OHIO/NW PA WILL FILL IN QUICKLY AS DIURNAL HEATING INCREASES...WHILE A GOOD DEAL OF SUN IS EXPECTED IN THE DRIER AIR IN NW OHIO. HIGHS WILL RANGE FROM 77-85 AND WILL BE HIGHEST IN THE WEST WHERE THEY WILL RECEIVE MORE SUN. WEDNESDAY NIGHT WILL BE MOSTLY DRY AS WEAK COLD FRONT PUSHES SOUTH WITH NEGATIVE THETA-E ADVECTION THROUGH THE COLUMN. WEAK HIGH PRESSURE ALSO BUILDS IN BEHIND THE DEPARTING SURFACE LOW WHICH SHOULD REDUCE CHANCES FOR PRECIPITATION DOWNWIND OF LAKE ERIE IN NE OH/NW PA ON THURSDAY. FARTHER SOUTH...SCATTERED THUNDERSTORMS ARE EXPECTED TO FIRE ALONG STALLED BOUNDARY ON THURSDAY. THURSDAY NIGHT COULD ALSO BE ACTIVE ACROSS THE SW HALF OF THE FORECAST AREA AS ENERGY MOVES AROUND THE BUILDING RIDGE THURSDAY NIGHT. THIS WILL BE FOLLOWED BY A WARM FRONT STARTING TO LIFT BACK NORTH ON FRIDAY. THIS WILL BE THE BEGINNING OF THE WARMING TREND FOR THE WEEKEND...WITH HIGHS REACHING THE MID TO UPPER 80S IN THE WEST ON FRIDAY. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE LONG TERM BEGINS ON SATURDAY WITH BOTH THE GFS AND ECMWF SHOWING AN UPPER LEVEL HIGH CENTERED OVER THE SOUTHEASTERN STATES. A RIDGE WILL EXTEND NORTH INTO THE CENTRAL LAKES. NOT MUCH CHANGES THROUGH SUNDAY INTO MONDAY EXCEPT THAT LOW PRESSURE MOVING THROUGH SOUTHERN CANADA WILL TILT THE AXIS OF THE RIDGE EAST A BIT HOWEVER IT SHOULD STILL REMAIN WEST OF THE AREA. TUESDAY THE LOW MOVES TO NORTHERN ONTARIO FLATTENING THE RIDGE ACROSS THE LAKES. GIVEN THE RIDGE POSITION...WOULD EXPECT THAT ANY CONVECTION THAT GOES OVER THE TOP OF THE RIDGE WILL DESCEND ON THE REGION FROM THE NORTH. FOR NOW THOUGH IT WOULD BE FAIRLY DIFFICULT TO ANTICIPATE TIMING OTHER THAT A SMALL CHANCE POP FOR AFTERNOON AND EARLY EVENING CONVECTION. WILL HAVE A SLIGHT CHANCE POP IN FOR THE OVERNIGHT AND EARLY MORNING PERIODS. ALSO...GUIDANCE SUGGESTS MORE CLOUD COVER THEN SEEMS REASONABLE GIVEN THE RIDGE SO LOWERED CLOUD PERCENTAGES TO GET PARTLY CLOUDY THROUGH MOST OF THE PERIOD. TEMPS AT OR ABOVE NORMAL. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... CONVECTION CONTINUES TO DEVELOP OVER PORTIONS OF THE AREA AS LOW PRESSURE DIGS INTO THE CENTRAL GREAT LAKES. AFTER THIS EARLY MORNING CONVECTION IT APPEARS MOST OF THE THUNDERSTORMS WILL BE NEAR AND EAST OF INTERSTATE 71. AREAS OF FOG WILL BE POSSIBLE TOWARD SUNRISE WHERE THE RAIN HAS STOPPED. WINDS WILL GENERALLY BE BELOW 12 KNOTS FROM THE SOUTH AND SOUTHWEST. HOWEVER WESTERN AREAS MAY SEE WINDS AROUND TO THE WEST IN THE WAKE OF A WEAK FRONT. OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH FRIDAY. && .MARINE... LOW PRESSURE OVER THE GREAT LAKES WILL CONTINUE THROUGH TONIGHT AND TUESDAY INTO MID WEEK...EVENTUALLY REACHING WESTERN NEW YORK BY THURSDAY MORNING. FLOW AROUND THE LOW IS NOT PARTICULARLY STRONG SO AM EXPECTING VARIABLE BUT GENERALLY LIGHT WINDS THROUGH THE PERIOD RESULTING IN WAVES OF 2 FEET OR LESS ON THE LAKE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KEC NEAR TERM...LOMBARDY SHORT TERM...KEC LONG TERM...TK AVIATION...MULLEN MARINE...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1223 AM EDT WED AUG 20 2014 .SYNOPSIS... LOW PRESSURE OVER LAKE MICHIGAN WILL SLOWLY MOVE TO THE EASTERN GREAT LAKES THROUGH THURSDAY...PUSHING A WEAK COLD FRONT SOUTH ACROSS THE AREA. HIGH PRESSURE WILL BUILD OVER LAKE ERIE BEHIND THIS SYSTEM THURSDAY NIGHT...SHIFTING TO THE EASTERN GREAT LAKES ON FRIDAY. A WARM FRONT WILL LIFT NORTH ACROSS THE AREA ON FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MAIN LINE OF SHOWERS AND THUNDERSTORMS MOVED EAST THROUGH THE AREA WITH SOME POCKETS OF MORE ACTIVITY MOVING EAST INTO THE REGION AT THIS TIME. ANOTHER LINE IS TRYING TO GET ORGANIZED OVER WESTERN OHIO. POTENTIAL EXISTS THAT SOUTHERN PART OF THE LINE WILL TRY TO FILL IN. NORTHERN PART IS NOT AS PROMISING. ALONG THIS LINE IS AN AREA OF CONVERGENCE AND SOME INSTABILITY TO SUPPORT THE ACTIVITY AS IT MOVES EAST. LATEST NAM OUTPUT SHOWS THIS AREA OF CONVERGENCE MOVING HALFWAY EAST ACROSS THE FORECAST AREA BEFORE THE CONVERGENCE WEAKENS WITH TIME. HOWEVER...LATEST HRRR MODEL DOES SHOW THE WEAKENING A BIT ACROSS THE CENTRAL PORTIONS AND THEN NEW DEVELOPMENT TAKES PLACE ALONG THE OUTFLOW BOUNDARY FURTHER EAST. MINOR ADJUSTMENTS TO TEMPERATURES WITH THIS UPDATE. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... NEARLY VERTICALLY STACKED UPPER LEVEL AND SURFACE LOW WILL BE OVER THE CENTRAL GREAT LAKES ON WEDNESDAY. A MOIST AND UNSTABLE AIR MASS WILL RESIDE WITHIN THE AREA OF SOUTHERLY FLOW AHEAD OF THE SURFACE LOW ACROSS MAINLY NE OHIO AND NW PA. CAPES ARE EXPECTED TO INCREASE TO AROUND 2500 J/KG WITH SEVERAL MECHANISMS FOR CONVECTIVE INITIATION DURING THE AFTERNOON. STORMS WILL FIRE DURING THE AFTERNOON AS THE LOW SLOWLY MOVES EASTWARD. HIGHER RESOLUTION MODELS ALSO SHOW SOME CONVERGENCE DOWNWIND OF LAKE ERIE THAT WILL SET UP SOUTH OF I-90. LARGE SCALE FORCING WILL ALSO INCREASE DURING THE LATE AFTERNOON AS A 35 KNOT MID-LEVEL JET STREAK MOVES THROUGH THE NORTHWESTERLY FLOW ON THE BACK SIDE OF THE TROUGH. ALL OF THIS COMBINES TO MAKE THUNDERSTORMS LIKELY ON THURSDAY ACROSS AT LEAST THE EASTERN HALF OF THE FORECAST AREA. LESS CERTAIN IS IF ANYTHING CAN FIRE ACROSS NW OHIO AHEAD OF THE JET STREAK WHICH CAN NOT BE ENTIRELY RULED OUT SO WILL LEAVE A LOW POP IN THE NW OHIO. WHATEVER BREAKS EXIST IN THE CLOUDS TO START THE DAY IN NE OHIO/NW PA WILL FILL IN QUICKLY AS DIURNAL HEATING INCREASES...WHILE A GOOD DEAL OF SUN IS EXPECTED IN THE DRIER AIR IN NW OHIO. HIGHS WILL RANGE FROM 77-85 AND WILL BE HIGHEST IN THE WEST WHERE THEY WILL RECEIVE MORE SUN. WEDNESDAY NIGHT WILL BE MOSTLY DRY AS WEAK COLD FRONT PUSHES SOUTH WITH NEGATIVE THETA-E ADVECTION THROUGH THE COLUMN. WEAK HIGH PRESSURE ALSO BUILDS IN BEHIND THE DEPARTING SURFACE LOW WHICH SHOULD REDUCE CHANCES FOR PRECIPITATION DOWNWIND OF LAKE ERIE IN NE OH/NW PA ON THURSDAY. FARTHER SOUTH...SCATTERED THUNDERSTORMS ARE EXPECTED TO FIRE ALONG STALLED BOUNDARY ON THURSDAY. THURSDAY NIGHT COULD ALSO BE ACTIVE ACROSS THE SW HALF OF THE FORECAST AREA AS ENERGY MOVES AROUND THE BUILDING RIDGE THURSDAY NIGHT. THIS WILL BE FOLLOWED BY A WARM FRONT STARTING TO LIFT BACK NORTH ON FRIDAY. THIS WILL BE THE BEGINNING OF THE WARMING TREND FOR THE WEEKEND...WITH HIGHS REACHING THE MID TO UPPER 80S IN THE WEST ON FRIDAY. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE LONG TERM BEGINS ON SATURDAY WITH BOTH THE GFS AND ECMWF SHOWING AN UPPER LEVEL HIGH CENTERED OVER THE SOUTHEASTERN STATES. A RIDGE WILL EXTEND NORTH INTO THE CENTRAL LAKES. NOT MUCH CHANGES THROUGH SUNDAY INTO MONDAY EXCEPT THAT LOW PRESSURE MOVING THROUGH SOUTHERN CANADA WILL TILT THE AXIS OF THE RIDGE EAST A BIT HOWEVER IT SHOULD STILL REMAIN WEST OF THE AREA. TUESDAY THE LOW MOVES TO NORTHERN ONTARIO FLATTENING THE RIDGE ACROSS THE LAKES. GIVEN THE RIDGE POSITION...WOULD EXPECT THAT ANY CONVECTION THAT GOES OVER THE TOP OF THE RIDGE WILL DESCEND ON THE REGION FROM THE NORTH. FOR NOW THOUGH IT WOULD BE FAIRLY DIFFICULT TO ANTICIPATE TIMING OTHER THAT A SMALL CHANCE POP FOR AFTERNOON AND EARLY EVENING CONVECTION. WILL HAVE A SLIGHT CHANCE POP IN FOR THE OVERNIGHT AND EARLY MORNING PERIODS. ALSO...GUIDANCE SUGGESTS MORE CLOUD COVER THEN SEEMS REASONABLE GIVEN THE RIDGE SO LOWERED CLOUD PERCENTAGES TO GET PARTLY CLOUDY THROUGH MOST OF THE PERIOD. TEMPS AT OR ABOVE NORMAL. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... ONGOING CONVECTION WILL KEEP THINGS INTERESTING THIS EVENING. THE WORST OF THE ACTIVITY REMAINS OVER LAKE ERIE BUT SCATTERED STORMS ARE LIKELY THROUGH MIDNIGHT OR SO. WILL HAVE TO WATCH THE STORMS APPROACHING KFDY TO MAKE SURE THEY DON`T BECOME SEVERE. OUTFLOW FROM THE STORMS OVER THE LAKE WILL LIKELY IMPACT KCLE IN AN HOUR OR SO AND COULD SEE SOME BRIEF GUSTS TO 30 KNOTS WITH ANY OF THE STRONGER STORMS. WIDESPREAD MVFR FOG IS LIKELY AFTER MIDNIGHT WITH PATCHY IFR AT THE USUAL INLAND SPOTS. THERE WILL LIKELY BE MORE PRECIP IN THE EAST TOMORROW BUT WILL BROAD BRUSH IT FOR NOW. LIGHT S TO SW FLOW WILL EVENTUALLY BECOME WESTERLY ON WEDNESDAY AFTERNOON. OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THROUGH FRIDAY. && .MARINE... LOW PRESSURE OVER THE GREAT LAKES WILL CONTINUE THROUGH TONIGHT AND TUESDAY INTO MID WEEK...EVENTUALLY REACHING WESTERN NEW YORK BY THURSDAY MORNING. FLOW AROUND THE LOW IS NOT PARTICULARLY STRONG SO AM EXPECTING VARIABLE BUT GENERALLY LIGHT WINDS THROUGH THE PERIOD RESULTING IN WAVES OF 2 FEET OR LESS ON THE LAKE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KEC NEAR TERM...LOMBARDY SHORT TERM...KEC LONG TERM...TK AVIATION...KUBINA MARINE...TK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
205 PM EDT WED AUG 20 2014 .SYNOPSIS... A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE MISSISSIPPI RIVER VALLEY OVER THE NEXT FEW DAYS AND LINGER FOR THE REST OF THE WORK WEEK...RESULTING IN ABOVE NORMAL TEMPERATURES. A WEAK COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST SATURDAY AND BRING SOME MINOR RELIEF FROM THE HEAT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 155 PM...PERSISTENT SMALL STRONG TO OCCASIONALLY SEVERE CONVECTIVE CLUSTER CONTINUES TO DROP SOUTHEAST ACROSS THE NC FOOTHILLS. SCT CONVECTION IS FINALLY BEGINNING TO UNZIP A BIT ALONG THE OUTFLOW BOUNDARY ALONG THE I-40 CORRIDOR INTO THE NW PIEDMONT. OTHERWISE...THE LATEST SPC MESOANALYSIS DEPICTS A MINIMUM IN CAPE ACROSS THE AREA...WITH CAPE EXCEEDING 3000 J/KG JUST TO OUR EAST... AND MORE THAN 4000 J/KG ACROSS EAST TENN INTO NRN/CTRL GEORGIA. THIS IS WHERE THE BEST CONVECTIVE COVERAGE IS ONGOING. WE HAVE DELAYED THE BEST POPS UNTIL LATE IN THE AFTERNOON AND TOWARD EARLY EVENING...WHEN INSTABILITY SHOULD BE GREATEST AND CHANCES WILL ALSO INCREASE FOR UPSTREAM ACTIVITY...POSSIBLY ORGANIZING UPSCALE...TO MOVE INTO THE FORECAST AREA. BRIEF LARGE HAIL AND DAMAGING WINDS WILL REMAIN POSSIBLE...WITH DOWNBURST POTENTIAL ENHANCED WITH ANY ORGANIZED CLUSTERS. AS OF 11 AM...A SMALL CLUSTER OF DEEP CONVECTION IS APPROACHING THE NORTHERN NC MTNS ATTM...THUS POPS HAVE BEEN INCREASED TO LIKELY IN THE AREAS NORTH OF I-26 ALONG THE TENN BORDER. THE PREVIOUS REMNANT CONVECTIVE AREA DISSIPATED AS IT MOVED EAST OF THE MTNS. HOWEVER... THE ATMOSPHERE IS HEATING STRONGLY DOWNSTREAM OF THE HIGH TERRAIN. REGIONAL RAOBS PAINTED A RATHER STARK CONTRAST FROM THIS TIME YESTERDAY...ESP AT KFFC...WHERE A LAYER OF NEAR-DRY ADIABATIC LAPSE RATES WERE OBSERVED BETWEEN H8 AND H6. AS A RESULT...THE AIRMASS IS RAPIDLY DESTABILIZING EAST OF THE MTNS...WITH CAPE ALREADY EXCEEDING 1500 J/KG ACROSS THE FOOTHILLS AS OF 14Z. IT APPEARS LIKELY THAT CAPE WILL INCREASE TO THE NEIGHBORHOOD OF 3000 J/KG THIS AFTERNOON. CONVECTION IS ALREADY SHOWING SIGNS OF FANNING OUT ALONG THE OUTFLOW BOUNDARY ACROSS NORTHEAST TENN...AND WITH CAPE INCREASING STRONGLY DOWNSTREAM...IT SEEMS ENTIRELY PLAUSIBLE THAT SCATTERED CONVECTION WILL CONTINUE TO DEVELOP ALONG THE BOUNDARY AS IT PUSHES EAST OF THE MTNS BY EARLY AFTERNOON (THE LATEST HRRR IS SUGGESTING A SIMILAR SCENARIO). AS SUCH...POPS HAVE BEEN INCREASED BY 10-20 PERCENT IN MOST AREAS THIS AFTERNOON...WITH 40 POPS NOW BEING FEATURED AS FAR SOUTHEAST AS THE I-85 CORRIDOR. POPS HAVE ALSO BEE INCREASED FOR THIS EVENING. AN AXIS OF CAPE > 3000 IS ALREADY BEING ANALYZED ACROSS MIDDLE TENN INTO SE KENTUCKY. SHORT TERM GUIDANCE ALSO DEPICTS A CORRIDOR OF 20-30KTS OF LOW LEVEL SHEAR THIS AFTERNOON FROM EASTERN KENTUCKY INTO SOUTHWEST NC. A CONSENSUS OF MESOSCALE MODEL GUIDANCE WOULD SUGGEST ORGANIZED MCS DEVELOPMENT IN THESE AREAS BY LATE AFTERNOON...POSSIBLY DROPPING SOUTHEAST INTO THE FORECAST AREA THIS EVENING. HOW THIS PLAYS OUT FOR OUR AREA MAY DEPEND LARGELY UPON THIS AFTERNOON/S CONVECTIVE EVOLUTION...BUT IT SEEMS THE AREA MOST LIKELY TO BE AFFECTED WOULD BE ACROSS (ROUGHLY) THE NORTHWEST HALF OF THE FORECAST AREA...WHERE POPS WERE INCREASED TO 40-50 PERCENT THIS EVENING. LOWERING FREEZING LEVELS AND LARGE DCAPE SHOULD SUPPORT A RISK OF ISOLATED LARGE HAIL AS WELL AS DAMAGING WINDS...WITH THE POTENTIAL FOR AN ENHANCED DOWNBURST RISK WITH ANY UPSCALE ORGANIZATION. 1030 UTC UPDATE...POPS HAVE BEEN ADJUSTED PER RADAR TRENDS...WITH A DECREASE EARLY ON. SKY COVER WAS UPDATED FROM INFRARED SATELLITE IMAGERY...ALSO RESULTING IN A DECREASE. AREAS OF FOG WERE REDUCED BASED ON OBSERVATIONS AND DEW POINT DEPRESSIONS. AT 300 AM EDT TUESDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST COAST TODAY...WHILE AN UPPER RIDGE BUILDS NORTH OVER THE MS RIVER VALLEY. SEVERAL WEAK SHORTWAVES WILL CROSS OUR AREA TODAY AND TONIGHT IN NW FLOW ALOFT....WHILE A COLD FRONT ADVANCES SLOWLY FORM THE NE. IT IS UNCLEAR WHETHER THE FRONT WILL MAKE IT VERY FAR INTO OUR AREA...BUT ITS GENERAL PROXIMITY MAY FOCUS CONVECTION ACROSS OUR NORTHERN TIER OF COUNTIES. EVEN IF THE FRONT REMAINS OFF TO THE NORTHEAST...OUR AREA WILL BE IN A MOIST UNSTABLE AIR MASS...AND PASSING SHORTWAVES WILL PROVIDE SUPPORT FOR CONVECTION. MOISTURE WILL BE SOMEWHAT LIMITED...AND STEERING FLOW GREAT ENOUGH TO KEEP CELLS MOVING...LIMITING THE POTENTIAL FOR HEAVY RAINFALL. ROBUST CAPE WILL BE PRESENT...AND DRY AIR WILL BE AVAILABLE FOR EVAPORATIVE COOLING...PROVIDING SUPPORT FOR WIND GUSTS AND HAIL. HIGH TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL. SOME ELEVATED INSTABILITY WILL LINGER THROUGH TONIGHT...AND IF ANY MCS ROUNDING THE CORNER OF THE RIDGE REACHES OUR AREA...IT MAY WELL SURVIVE. STEERING FLOW AND A LACK OF DEEP MOISTURE WILL LIMIT HEAVY RAINFALL POTENTIAL. MINIMUM TEMPERATURES WILL RUN ABOVE NORMAL IN A MOIST AIRMASS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...A LARGE UPPER RIDGE WILL PERSIST ACRS THE LWR-MID MS VALLEY...EXTENDING EAST ACRS THE SOUTHEAST STATES THRU THE SHORT TERM. THE LATEST GUIDANCE SHOWS THAT A RING OF FIRE PATTERN WILL SET UP...WITH A SERIES OF SHORTWAVES AND ASSOCIATED CLUSTERS OF CONVECTION WILL RIDE OVER TOP OF THE RIDGE...FROM THE UPR MIDWEST/SRN GREAT LAKES...TO THE MID ATLANTIC. IT LOOKS LIKE MOST OF THE ASSOCIATED ACTIVITY WILL STAY NORTH OF THE CWFA. HOWEVER...THE NRN ZONES (GENERALLY I-40 CORRIDOR AND NORTH)...MAY GET BRUSHED BY A POSSIBLE MCS AT SOME POINT. NOT MUCH CHANGE WAS MADE TO THE POPS. STILL EXPECT AT LEAST A HANDFUL OF DIURNALLY-DRIVEN CONVECTION...AS STEEP MID LVL LAPSE RATES REMAIN ATOP THE REGION. MODELS ARE TRENDING WARMER FOR THURSDAY AND FRIDAY...SO I BUMPED UP TEMPS ABOUT A CATEGORY...EVEN MORE IN THE NW NC PIEDMONT...WHERE WE PREVIOUSLY THOUGHT A BACKDOOR COLD FRONT WOULD PUSH IN BY FRIDAY. THIS RESULTS IN ABOVE NORMAL TEMPS...WITH UPR 80S IN THE MTN VALLEYS AND MID-UPR 90S ACRS THE PIEDMONT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 1230 PM WEDNESDAY...MEDIUM RANGE MODELS ARE IN DECENT ENUF AGREEMENT WITH RESPECT TO THE MEAN PATTERN FOR THE FIRST HALF OF THE EXTENDED PERIOD FEATURING LLVL RIDGING POKING SSW INTO THE CWFA. THE COMBINATION OF THE LLVL EASTERLY FLOW AND THE HIGHLY AMPLIFIED NLY FLOW SHOULD RESULT IN ENUF FORCING FOR AT LEAST SCATTERED SHOWERS...AND MAX TEMPERATURES A FEW DEG F BELOW PERSISTENCE AND A CATEGORY OR TWO BELOW CLIMO SUNDAY AND MONDAY. WITH LLVL RIDGING LIKELY TO LINGER THRU TUESDAY...THERE REMAINS ABOVE NORMAL CONFIDENCE THAT MAXIMUM TEMPERATURES WILL CONTINUE TO AVERAGE BELOW CLIMO. IT REMAINS TO BE SEEN ON JUST HOW MUCH FORCING IS AVAILABLE TO TRIGGER SHOWER ACTIVITY...SO JUST A TOKEN SLIGHT AND/OR SMALL POP WILL REMAIN. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AT KCLT AND ELSEWHERE...CONVECTION AT THIS MOMENT IS PRIMARILY LIMITED TO A SMALL/PERSISTENT CLUSTER OF STRONG TO SEVERE CONVECTION OVER THE SOUTHERN NC FOOTHILLS. THIS WILL NOT THREATEN ANY OF THE TAF SITES IN THE NEAR TERM. HOWEVER...THERE ARE SIGNS THAT SCATTERED CONVECTION MAY BE IN THE PROCESS OF /FANNING OUT/ ALONG THE OUTFLOW BOUNDARY LAID DOWN BY THIS CONVECTION. THEREFORE...TEMPOS FOR TSRA WILL BE CONTINUED AT KCLT...AND INTRODUCED AT KGSP THROUGH THE AFTERNOON. THE TEMPO HAS BEEN SCALED BACK TO SHRA AT KHKY AND COMPLETELY REMOVED AT KAVL...SINCE THE OUTFLOW HAS NOW ESSENTIALLY PASSED THEM. HOWEVER...ADDITIONAL DEVELOPMENT WILL BE POSSIBLE NEAR THESE SITES AND ALL OTHER TAF SITES THIS AFTERNOON. CONVECTION MAY ALSO ORGANIZE ACROSS THE TENN VALLEY THIS AFTERNOON AND PUSH SOUTHEAST ACROSS THE SOUTHERN APPALACHIANS AND SURROUNDING AREAS INTO THE EVENING. THEREFORE...A VCTS/VCSH WILL BE CARRIED AT ALL TERMINALS THROUGH ABOUT 03Z. EVEN OUR MOST RELIABLE GUIDANCE IS ONCE AGAIN HITTING THE FOG HARD LATE TONIGHT...AS IT HAS BEEN DOING THE PASTS SEVERAL MORNINGS... WITH VERY POOR VERIFICATION RESULTS. THEREFORE...WE HAVE IMPROVED THE VISBY FORECAST CONSIDERABLY OVER WHAT GUIDANCE IS ADVERTISING... BUT THIS IS STILL RESULTING IN A 3SM FORECAST AT KAVL. OTHERWISE... VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD OUTSIDE OF SHRA/ TSRA. OUTLOOK...SCT AFTERNOON CONVECTION AND PATCHY EARLY MORNING FOG WILL REMAIN IN THE FORECAST THROUGH THE WEEK. THERE WILL ALSO BE AN OUTSIDE CHANCE FOR REMNANT ORGANIZED CONVECTION APPROACHING THE AREA FROM THE NW DURING THE LATE NIGHT/EARLY MORNING HOURS. CONFIDENCE TABLE... 18-24Z 00-06Z 06-12Z 12-18Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 95% HIGH 95% HIGH 95% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 95% HIGH 91% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...ARK NEAR TERM...JAT/JDL SHORT TERM...ARK LONG TERM...ARK AVIATION...JDL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1124 AM EDT WED AUG 20 2014 .SYNOPSIS... A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE MISSISSIPPI RIVER VALLEY OVER THE NEXT FEW DAYS AND LINGER FOR THE REST OF THE WORK WEEK...RESULTING IN ABOVE NORMAL TEMPERATURES. A WEAK COLD FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST SATURDAY AND BRING SOME MINOR RELIEF FROM THE HEAT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 11 AM...A SMALL CLUSTER OF DEEP CONVECTION IS APPROACHING THE NORTHERN NC MTNS ATTM...THUS POPS HAVE BEEN INCREASED TO LIKELY IN THE AREAS NORTH OF I-26 ALONG THE TENN BORDER. THE PREVIOUS REMNANT CONVECTIVE AREA DISSIPATED AS IT MOVED EAST OF THE MTNS. HOWEVER... THE ATMOSPHERE IS HEATING STRONGLY DOWNSTREAM OF THE HIGH TERRAIN. REGIONAL RAOBS PAINTED A RATHER STARK CONTRAST FROM THIS TIME YESTERDAY...ESP AT KFFC...WHERE A LAYER OF NEAR-DRY ADIABATIC LAPSE RATES WERE OBSERVED BETWEEN H8 AND H6. AS A RESULT...THE AIRMASS IS RAPIDLY DESTABILIZING EAST OF THE MTNS...WITH CAPE ALREADY EXCEEDING 1500 J/KG ACROSS THE FOOTHILLS AS OF 14Z. IT APPEARS LIKELY THAT CAPE WILL INCREASE TO THE NEIGHBORHOOD OF 3000 J/KG THIS AFTERNOON. CONVECTION IS ALREADY SHOWING SIGNS OF FANNING OUT ALONG THE OUTFLOW BOUNDARY ACROSS NORTHEAST TENN...AND WITH CAPE INCREASING STRONGLY DOWNSTREAM...IT SEEMS ENTIRELY PLAUSIBLE THAT SCATTERED CONVECTION WILL CONTINUE TO DEVELOP ALONG THE BOUNDARY AS IT PUSHES EAST OF THE MTNS BY EARLY AFTERNOON (THE LATEST HRRR IS SUGGESTING A SIMILAR SCENARIO). AS SUCH...POPS HAVE BEEN INCREASED BY 10-20 PERCENT IN MOST AREAS THIS AFTERNOON...WITH 40 POPS NOW BEING FEATURED AS FAR SOUTHEAST AS THE I-85 CORRIDOR. POPS HAVE ALSO BEE INCREASED FOR THIS EVENING. AN AXIS OF CAPE > 3000 IS ALREADY BEING ANALYZED ACROSS MIDDLE TENN INTO SE KENTUCKY. SHORT TERM GUIDANCE ALSO DEPICTS A CORRIDOR OF 20-30KTS OF LOW LEVEL SHEAR THIS AFTERNOON FROM EASTERN KENTUCKY INTO SOUTHWEST NC. A CONSENSUS OF MESOSCALE MODEL GUIDANCE WOULD SUGGEST ORGANIZED MCS DEVELOPMENT IN THESE AREAS BY LATE AFTERNOON...POSSIBLY DROPPING SOUTHEAST INTO THE FORECAST AREA THIS EVENING. HOW THIS PLAYS OUT FOR OUR AREA MAY DEPEND LARGELY UPON THIS AFTERNOON/S CONVECTIVE EVOLUTION...BUT IT SEEMS THE AREA MOST LIKELY TO BE AFFECTED WOULD BE ACROSS (ROUGHLY) THE NORTHWEST HALF OF THE FORECAST AREA...WHERE POPS WERE INCREASED TO 40-50 PERCENT THIS EVENING. LOWERING FREEZING LEVELS AND LARGE DCAPE SHOULD SUPPORT A RISK OF ISOLATED LARGE HAIL AS WELL AS DAMAGING WINDS...WITH THE POTENTIAL FOR AN ENHANCED DOWNBURST RISK WITH ANY UPSCALE ORGANIZATION. 1030 UTC UPDATE...POPS HAVE BEEN ADJUSTED PER RADAR TRENDS...WITH A DECREASE EARLY ON. SKY COVER WAS UPDATED FROM INFRARED SATELLITE IMAGERY...ALSO RESULTING IN A DECREASE. AREAS OF FOG WERE REDUCED BASED ON OBSERVATIONS AND DEW POINT DEPRESSIONS. AT 300 AM EDT TUESDAY...AN UPPER TROUGH WILL AMPLIFY ALONG THE EAST COAST TODAY...WHILE AN UPPER RIDGE BUILDS NORTH OVER THE MS RIVER VALLEY. SEVERAL WEAK SHORTWAVES WILL CROSS OUR AREA TODAY AND TONIGHT IN NW FLOW ALOFT....WHILE A COLD FRONT ADVANCES SLOWLY FORM THE NE. IT IS UNCLEAR WHETHER THE FRONT WILL MAKE IT VERY FAR INTO OUR AREA...BUT ITS GENERAL PROXIMITY MAY FOCUS CONVECTION ACROSS OUR NORTHERN TIER OF COUNTIES. EVEN IF THE FRONT REMAINS OFF TO THE NORTHEAST...OUR AREA WILL BE IN A MOIST UNSTABLE AIR MASS...AND PASSING SHORTWAVES WILL PROVIDE SUPPORT FOR CONVECTION. MOISTURE WILL BE SOMEWHAT LIMITED...AND STEERING FLOW GREAT ENOUGH TO KEEP CELLS MOVING...LIMITING THE POTENTIAL FOR HEAVY RAINFALL. ROBUST CAPE WILL BE PRESENT...AND DRY AIR WILL BE AVAILABLE FOR EVAPORATIVE COOLING...PROVIDING SUPPORT FOR WIND GUSTS AND HAIL. HIGH TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL. SOME ELEVATED INSTABILITY WILL LINGER THROUGH TONIGHT...AND IF ANY MCS ROUNDING THE CORNER OF THE RIDGE REACHES OUR AREA...IT MAY WELL SURVIVE. STEERING FLOW AND A LACK OF DEEP MOISTURE WILL LIMIT HEAVY RAINFALL POTENTIAL. MINIMUM TEMPERATURES WILL RUN ABOVE NORMAL IN A MOIST AIRMASS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...A LARGE UPPER RIDGE WILL PERSIST ACRS THE LWR-MID MS VALLEY...EXTENDING EAST ACRS THE SOUTHEAST STATES THRU THE SHORT TERM. THE LATEST GUIDANCE SHOWS THAT A RING OF FIRE PATTERN WILL SET UP...WITH A SERIES OF SHORTWAVES AND ASSOCIATED CLUSTERS OF CONVECTION WILL RIDE OVER TOP OF THE RIDGE...FROM THE UPR MIDWEST/SRN GREAT LAKES...TO THE MID ATLANTIC. IT LOOKS LIKE MOST OF THE ASSOCIATED ACTIVITY WILL STAY NORTH OF THE CWFA. HOWEVER...THE NRN ZONES (GENERALLY I-40 CORRIDOR AND NORTH)...MAY GET BRUSHED BY A POSSIBLE MCS AT SOME POINT. NOT MUCH CHANGE WAS MADE TO THE POPS. STILL EXPECT AT LEAST A HANDFUL OF DIURNALLY-DRIVEN CONVECTION...AS STEEP MID LVL LAPSE RATES REMAIN ATOP THE REGION. MODELS ARE TRENDING WARMER FOR THURSDAY AND FRIDAY...SO I BUMPED UP TEMPS ABOUT A CATEGORY...EVEN MORE IN THE NW NC PIEDMONT...WHERE WE PREVIOUSLY THOUGHT A BACKDOOR COLD FRONT WOULD PUSH IN BY FRIDAY. THIS RESULTS IN ABOVE NORMAL TEMPS...WITH UPR 80S IN THE MTN VALLEYS AND MID-UPR 90S ACRS THE PIEDMONT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 315 AM WEDNESDAY...THE UPPER FLOW LOOKS TO BECOME MORE NORTHERLY ATOP THE CWFA FOR SATURDAY AND SUNDAY...AS RIDGE AXIS DRIFTS SLIGHTLY EAST...WHILE A LARGE TROF REMAINS NEARLY STATIONARY JUST OFF THE EAST COAST. WHILE THE MEDIUM RANGE GUIDANCE HAS DELAYED THE TIMING OF A BACKDOOR COLD FRONTAL PASSAGE BY A FULL DAY...THEY STILL SHOW IT COMING THRU...WITH SLIGHTLY COOLER TEMPS AND INCREASED CHC FOR PRECIP. BOTH THE 00Z/20 GFS AND ECMWF SHOW WEDGE-LIKE CONFIGURATION FOR SUNDAY...WITH A 1021-1023 MB SFC HIGH OVER THE CANADIAN MARITIMES...NOSING A RIDGE AXIS SW ALONG THE EAST COAST. LIGHT NELY LLVL FLOW AND INCREASED CLOUDS SHUD KEEP TEMPS CLOSER TO NORMAL...ESP SUNDAY. FOR MONDAY AND TUESDAY...THE SFC HIGH SINKS SOUTHWARD...KEEPING COOLER LLVL THICKNESSES ACRS THE REGION...AND CONTINUED LIGHT ELY LLVL FLOW. I WILL FCST TEMPS BACK TO NORMAL...EVEN SLIGHTLY BELOW NORMAL IN THE NW NC PIEDMONT...WITH CONTINUE SLGT CHC TO CHC POPS. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... AT KCLT...FOG HAS FAILED TO DEVELOP...AND THE DEW POINT DEPRESSION REMAINS THREE DEGREES. CALM WINDS ARE EXPECTED TO BECOME LIGHT NE THIS MORNING...THEN BACK TO SW BY AFTERNOON...BEFORE VEERING TO WNW THIS EVENING. CONVECTIVE CHANCES REMAINS TOO LOW TO MENTION. LOW CLOUDS ARE EXPECTED TO INCREASE TODAY...BUT WITHOUT ENOUGH COVERAGE FOR A LOW VFR CIG. GUIDANCE DID NOT FAVOR FOG WEDNESDAY MORNING... BUT IF IT RAINS THIS AFTERNOON OR EVENING...FOG WOULD BE MORE LIKELY. ELSEWHERE...FOG HAS NOT DEVELOPED AS EXPECTED...EXCEPT IN A FEW NON TAF SITES THAT RECEIVED BETTER RAINFALL YESTERDAY...AND THE LITTLE TN RIVER VALLEY. CALM FOOTHILL WINDS MAY BRIEFLY COME UP FROM THE N OR W THIS MORNING...BEFORE BACKING TO SW. KAVL WINDS WILL REMAIN CHANNELED FROM THE NW. CONVECTIVE CHANCES ARE ONLY GREAT ENOUGH FOR A MENTION AT KAVL THIS AFTERNOON. GUIDANCE FAVORED VERY LOW VSBY IN FOG IN THE MOUNTAINS TONIGHT...BUT BASED ON RECENT PERFORMANCE... ONLY MVFR VSBY WILL BE CARRIED AT KAVL. OUTLOOK...SCT AFTERNOON CONVECTION AND PATCHY EARLY MORNING FOG WILL REMAIN IN THE FORECAST THROUGH THE WEEK. THERE WILL ALSO BE INCREASING CHANCES FOR REMNANT ORGANIZED CONVECTION APPROACHING THE AREA FROM THE NW DURING THE LATE NIGHT/EARLY MORNING HOURS. CONFIDENCE TABLE... 15-21Z 21-03Z 03-09Z 09-15Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 100% HIGH 100% MED 62% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...ARK NEAR TERM...JAT/JDL SHORT TERM...ARK LONG TERM...ARK AVIATION...JAT
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1254 PM CDT WED AUG 20 2014 .UPDATE... ISSUED AT 1008 AM CDT WED AUG 20 2014 CURRENT CONVECTION IN EASTERN NEBRASKA CONTINUES TO FILTER NORTHEASTWARD INTO PARTS OF NORTHWEST IA...EXTREME NORTHEAST NEB AND FAR SOUTHEAST SD THIS MORNING. THIS ACTIVITY IS ASSOCIATED WITH A 700MB WAVE...MARKED BY DECENT MID LEVEL FRONTOGENESIS AND STRONG MID LEVEL SPEED CONVERGENCE IN THAT AREA. SIGNALS BASED OFF OF THE 12Z NAM CONTINUE TO POINT AT A GRADUAL WEAKENING OF THESE FEATURES INTO MIDDAY...ALBEIT THERE ARE SOME INDICATIONS THAT THE MID LEVEL CONVERGENCE MAY MAKE IT ALL THE WAY TOWARD THE IA GREAT LAKES AREA AND STORM LAKE EARLY THIS AFTERNOON. SO THAT WILL NEED MONITORED TO SEE IF WE NEED TO INCREASE AFTERNOON POPS IN THAT AREA. THIS CONVECTION HAS REALLY FOULED UP THE LOW LEVEL AND SURFACE BOUNDARIES THIS MORNING. AT THIS TIME...IT APPEARS THAT THE CURRENT POSITION OF THE MAIN WARM FRONT IS STILL AROUND THE OMAHA AREA PUSHED SOUTHWARD BY THE RAINFALL. THE VARIOUS SHORTER RANGE MODELS ARE ALL OVER THE MAP IN HOW THEY LIFT THE FRONT...OR FRONTS... NORTHWARD THIS AFTERNOON AND EVENING. FURTHERMORE...THE NEW 12Z NAM HAS THE MAIN SHORT WAVE LIFTING OUT MUCH FURTHER TO THE NORTHWEST AND NORTH OF OUR FORECAST AREA TONIGHT...WITH A LOBE OF UPPER QG FORCING ARCING SOUTHWARD INTO OUR AREA THIS EVENING FROM THE PARENT SHORT WAVE TO OUR NORTH. SO FOR TONIGHT...THE ACTUAL WAVE MAY NOT BE MUCH OF A PLAYER FOR OUR FORECAST AREA. IN ADDITION...THE SURFACE WIND SHIFT TO THE WEST DOES NOT TAKE PLACE UNTIL TOMORROW. SO ANY TORNADIC ACTIVITY WILL LIKELY HAVE TO BE CONFINED TO NEAR THE NORTHWARD LIFTING WARM FRONT WHICH IS DIFFICULT TO PROG. FOLLOWING THE 4KM NAM AND HRRR AS GUIDES SINCE THEY ARE VERY CLOSE... IT APPEARS THAT ONE WARM FRONTAL BOUNDARY SCOOTS NORTHWARD WITH THE WARM AIR ADVECTION TODAY...EVENTUALLY SETTING UP AND STALLING GENERALLY FROM CENTRAL ND...TO NORTHEAST SD...AND DOWN TO JUST NORTH OF MARSHALL MN THIS EVENING. BUT THERE IS A SECOND BOUNDARY AS WAS SHOWN YESTERDAY GENERALLY EXTENDING FROM LOW PRESSURE IN WEST CENTRAL SD...TO NEAR CHAMBERLAIN AND SIOUX CITY FROM 21Z TO 03Z TODAY...THEN WASHES OUT LIKELY DUE TO THE SHORT WAVE PASSAGE TO OUR NORTHWEST. AFTER ALL OF THIS MORNING AND MIDDAY CONVECTION IN OUR SOUTHERN ZONES...WORRIED THAT THE SOUTHERN PART OF THIS SECOND WARM FRONT IN OUR SOUTHERN ZONES COULD BE CAPPED OFF INTO THE EARLY EVENING HOURS. THIS WOULD INCLUDE THE SIOUX CITY... YANKTON AND STORM LAKE AREAS. BUT FURTHER WEST TOWARD CENTRAL SD WHERE STRONGER HEATING SHOULD OCCUR...THAT AREA COULD HAVE ENOUGH LOW LEVEL CURVATURE TO SPAWN ISOLATED TORNADOES THIS EVENING... AROUND THE CHAMBERLAIN AND MITCHELL AREAS...POSSIBLY EXTENDING NORTHWARD THEN THROUGH THE EVENING CLOSER TO HIGHWAY 14 IN OUR SOUTH DAKOTA ZONES. THE AFOREMENTIONED SURFACE LOW TO THE WEST SHOULD ALSO AID IN LOW LEVEL CURVATURE IN OUR FAR WESTERN ZONES. SO THIS APPEARS TO BE THE AREA RIGHT NOW FOR THE BEST CHANCE FOR TORNADIC ACTIVITY THIS EVENING...AT LEAST WITH THE CURRENT ANALYSIS. A BROADER RISK OF SEVERE WEATHER IS CERTAINLY WARRANTED THROUGH THE FORECAST AREA INTO THE MIDDLE OF THE NIGHT ALONG THE UPPER QG FORCING LOBE WHICH WAS MENTIONED ABOVE. WILL CONTINUE TO MONITOR FOR THE LATEST TRENDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CDT WED AUG 20 2014 SHOWERS AND THUNDERSTORMS EXPANDING THIS MORNING ALONG AND JUST SOUTH OF THE MISSOURI RIVER IN AN AREA OF INCREASING ISENTROPIC LIFT ON THE EDGE OF THE LOW LEVEL JET. THESE STORMS SHOULD GENERALLY REMAIN SUB SEVERE WITH BRIEF HEAVY RAIN...ALTHOUGH A FEW MARGINALLY SEVERE HAIL REPORTS ARE POSSIBLE. NOT REALLY A STRAIGHT FORWARD FORECAST AS WE GO THROUGH THE THE DAY TODAY INTO TONIGHT REGARDING CONVECTIVE EVOLUTION. THOUGHT IS THE ELEVATED CONVECTION THIS MORNING WILL GENERALLY BEGIN TO WEAKEN AND DISSIPATE BY MID MORNING AS THE AREA OF ISENTROPIC LIFT MOVES NORTH INTO DRIER AIR AND WE HAVE THE DIURNAL WEAKENING OF THE LOW LEVEL JET. THIS IS SUPPORTED BY A MAJORITY OF THE HI RES GUIDANCE. STILL SHOULD BE QUITE A BIT OF MID LEVEL CLOUDINESS THAT STICKS AROUND THROUGH THE DAY...AND POSSIBLY AN ISOLATED ELEVATED SHOWER OR STORM. BUT GENERALLY THINKING THE DAY ENDS UP MAINLY DRY...UNTIL WE SEE A REGENERATION THIS EVENING INTO THE OVERNIGHT...WHICH WILL BE DISCUSSED BELOW. HIGHS TODAY TRICKY AS WELL GIVEN CLOUD COVER UNCERTAINTY. WILL CONTINUE TO GO MIDDLE GROUND FOR HIGHS...WITH THE CLOUD COVER...HIGH BOUNDARY LAYER MOISTURE...AND SOUTHEASTERLY WINDS LIMITING MIXING. STILL SHOULD SEE MID TO UPPER 80S...WHICH COMBINED WITH THE HIGH DEWPOINTS WILL RESULT IN HEAT INDICES FROM THE UPPER 80S TO MID 90S...HIGHEST ALONG THE MISSOURI RIVER. MAIN FOCUS OF THIS FORECAST IS ON SEVERE WEATHER CHANCES THIS AFTERNOON AND TONIGHT. THROUGH THE DAY A WARM FRONT WILL WORK ITS WAY NORTH...SETTING UP SOMEWHERE ACROSS THE CWA BY THIS EVENING. THIS WILL ENHANCE LOW LEVEL SHEAR...WITH 0 TO 1 KM SHEAR EXPECTED TO BE 15 TO 20 KTS. GOOD TURNING OF THE WINDS WITH HEIGHT WILL ALSO RESULT IN DEEP LAYER SHEAR OF 40 OR MORE KTS...SUFFICIENT FOR SUPERCELLS. MLCAPE SHOULD BE PLENTIFUL AS WELL WITH MOST LOW LEVELS AND STEEP LAPSE RATES ALOFT RESULTING IN VALUES OF 2000 TO 3000 J/KG. AM CONCERNED ABOUT LOW LEVEL LAPSE RATES AND STABILITY THOUGH. MODEL SOUNDINGS SHOW A PRETTY GOOD CAP IN PLACE FOR MUCH OF THE DAY. LOW LEVEL FORCING DOES NOT SEEM STRONG ENOUGH TO OVERCOME THIS FOR MOST OF THE DAY...WHICH SHOULD KEEP SURFACE BASED CONVECTION AT BAY. THE UPPER WAVE WILL PASS BY TO OUR NORTH THIS AFTERNOON AND EVENING...BUT SHOULD PASS TOO FAR NORTH TO AID TOO MUCH IN CONVECTIVE DEVELOPMENT...AS 700 AND 500 MB HEIGHT FALLS ARE MINIMAL TO NON EXISTENT. THUS CONVECTIVE DEVELOPMENT WILL RELY MAINLY ON FORCING FROM THE WEST TO EAST MOVING COLD FRONT AND THE INCREASING LOW LEVEL JET TOWARDS 0Z. PREFER TIMING AND PLACEMENT CLOSE TO THE 06Z 4KM NAM...AND 4KM NMMB. THIS WOULD GIVEN CONVECTIVE INITIATION ACROSS CENTRAL SOUTH DAKOTA...WITH STORMS MOVING TOWARDS CHAMBERLAIN AND HURON BETWEEN 6PM AND 9PM. GIVEN THE AMPLE CAPE...STORMS SHOULD BE ABLE TO THEN PROGRESS ACROSS MUCH OF THE CWA...APPROACHING INTERSTATE 29 AFTER 10 PM AND THE EASTERN CWA AFTER MIDNIGHT. GIVEN THE GOOD MODEL AGREEMENT WENT WITH LIKELY POPS MOST AREAS...STAYED SHY OF GOING CATEGORICAL GIVEN THAT THERE IS STILL A CHANCE THE STORMS PEEL OFF TO THE NORTH CLOSER TO THE BETTER UPPER SUPPORT. IN GENERAL THE SPC SLIGHT RISK AND PROBABILITIES SEEM GOOD. GIVEN THE STEEP LAPSE RATES ALOFT AND GOOD SHEAR...LARGE HAIL OF TENNIS BALL SIZE WILL INITIALLY BE A THREAT. THIS VERY LARGE HAIL THREAT SHOULD MAINLY BE CLOSER TO WHERE STORMS INITIATE...LIKELY THE VICINITY OF THE JAMES RIVER OR WEST. AS STORMS MOVE EAST...SOME LARGE HAIL WILL STILL BE POSSIBLE...BUT THE STRONG WIND THREAT SHOULD ALSO INCREASE. TORNADO THREAT IS UNCERTAIN GIVEN THE UNCERTAINTY ON WHETHER STORMS BECOME NEAR SURFACE BASED. BUT GIVEN THE SHEAR MENTIONED ABOVE...CAN NOT RULE OUT A TORNADO OR TWO...GREATEST THREAT AGAIN APPEARS TO BE WEST OF INTERSTATE 29...PROBABLY EVEN ALONG OR JUST WEST OF THE JAMES RIVER. HEAVY RAIN WILL ALSO BE LIKELY IN ANY STORMS...WITH PWATS UP TO 3 STANDARD DEVIATIONS ABOVE NORMAL. STORMS SHOULD BE MOVING ENOUGH TO PREVENT A BIG FLASH FLOOD RISK...ALTHOUGH LOCALIZED FLOODING WOULD BE POSSIBLE IN THE HEAVIER STORMS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 341 AM CDT WED AUG 20 2014 THURSDAY LOOKS WARM...DRY AND HUMID AS UPPER LEVEL RIDGING BUILDS ACROSS THE REGION. MAIN CONCERN ON THURSDAY WILL BE HEAT INDICES. WHILE NOT QUITE TO ADVISORY LEVELS COULD SEE SOME LOWER TO MIDDLE 90S FOR HEAT INDICES WHICH WILL FEEL PRETTY HOT GIVEN THE EXPECTED 5 TO 10 MPH WIND. THURSDAY NIGHT INTO FRIDAY WILL SEE A TROUGH OF LOW PRESSURE SWING ONTO THE PLAINS WHICH WILL BRING A GRADUALLY INCREASING THREAT FOR THUNDERSTORMS. JUST A SLIGHT CHANCE THURSDAY NIGHT THEN BECOMING MUCH MORE LIKELY LATE FRIDAY AFTERNOON AND FRIDAY NIGHT. ISOLATED SEVERE THUNDERSTORMS AS WELL AS HEAVY RAIN WILL BE A THREAT. FRIDAY LIKELY TO BE PRETTY WARM AND HUMID...ESPECIALLY THE SOUTHEAST HALF OF THE CWA. HEAT INDICES LIKELY 90 TO 95 IN THESE AREAS. IN THE OUTER PERIODS (SATURDAY THROUGH TUESDAY)...A FAIRLY STRONG TROUGH OF LOW PRESSURE IS FORECAST TO MOVE ACROSS THE NORTHERN PLAINS SATURDAY NIGHT INTO SUNDAY NIGHT. THE TIMING AND STRENGTH ARE FAIRLY CONSISTENT IN THE LATEST MODELS SO WILL CONTINUE WITH MID RANGE POPS DURING THIS TIME. ALSO LOOKS LIKE A DECENT CHANCE FOR SOME SPOTTY HEAVY RAINFALL AS THE UPPER LEVEL FLOW LOOKS TO POSSIBLY BECOME PARALLEL TO THE LOW LEVEL BOUNDARY...WHICH COULD SUPPORT SOME TRAINING OF THUNDERSTORMS. A LITTLE TOO FAR OUT TO REALLY NAIL THIS DOWN BUT SOMETHING TO WATCH FOR. AS THE WAVE PASSES COOLER AIR WILL SETTLE INTO THE AREA AND WITH CONTINUED TROUGHING TO THE WEST THE THREAT FOR SHOWERS AND THUNDERSTORMS...AS WELL AS ADDITIONAL CLOUD COVER...WILL ALSO CONTINUE. TEMPERATURE GUIDANCE IN THIS TIME FRAME IS ALREADY BELOW NORMAL AND SEE NO REAL REASON TO STRAY TOO FAR FROM THAT. STATISTICALLY A GOOD SIGNAL WITH THE GFS MEX GUIDANCE BELOW CLIMATOLOGICAL NORMALS AND THE ENSEMBLE MEAN OUTPUT COOLER YET WHICH IS USUALLY A BIG HINT TO STAY BELOW THE COLDER MEN TEMPERATURES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1253 PM CDT WED AUG 20 2014 FOR STARTERS...VERY COMPLEX PATTERN IS NOT LENDING A LOT OF CONFIDENCE TO THE 18Z TAFS. THE PRIMARY WARM FRONT IS STILL WELL SOUTH OF OUR FORECAST AREA AT THIS TIME...WITH AN ELEVATED WARM FRONT CONTINUING TO LIFT NORTHWARD. CONVECTION IS CURRENTLY FIRING ALONG THE ELEVATED WARM FRONT...COUPLED WITH A SHORT WAVE NEAR 700MB ALONG OUR MO RIVER VALLEY ZONES. THOUGHTS ARE THAT THIS ACTIVITY WILL LIFT NORTHEASTWARD THROUGH THE AFTERNOON. THEREFORE PUT IN A CHANCE FOR THUNDERSTORMS FOR THE SIOUX FALLS TAF SITE VERY LATE THIS AFTERNOON AND VERY EARLY IN THE EVENING...BASED ON THE TIMING OF THE ELEVATED WARM FRONTAL PASSAGE. DYNAMICS SHOULD BE COMING TO A CLOSE AROUND SIOUX CITY BY MID AFTERNOON AS THE ELEVATED WARM FRONT LIFTS NORTHWARD. THEREFORE ENDED THE PRECIP THREAT FOR SIOUX CITY BY THAT TIME. AS THE PRIMARY UPPER SHORT WAVE LIFTS THROUGH NORTHERN SD AND NORTH DAKOTA THIS EVENING... CONTINUED TO PLACE THUNDERSTORM CHANCES FOR THE KHON TAF SITE DURING THE EVENING HOURS. BUT FURTHER SOUTH...THERE COULD BE A BREAK IN THE KFSD TAF SITE AFTER EARLY EVENING UNTIL THE OVERNIGHT HOURS. RIGHT DURING THE MIDDLE OF THE NIGHT...AS THE MAIN SHORT WAVE LIFTS NORTH OF KFSD...THERE COULD BE A PERIOD OF SHOWERS AND STORMS WHICH WERE MENTIONED IN THE KFSD TAF ASSOCIATED WITH THE MAIN WAVE IN NORTHERN SD...AS CONVECTION COULD DEVELOP SOUTHWARD INTO A STOUT LOW LEVEL JET. BUT KSUX MAY BE TOO FAR SOUTH FOR NOCTURNAL ACTIVITY TONIGHT...OR AT LEAST LESS CONFIDENT OF CONVECTION...SO LEFT KSUX DRY FOR TONIGHT. LASTLY...THE LATEST HIRES NAM IS HINTING AT STRATUS DEVELOPMENT FOR KHON AND KFSD LATE TONIGHT AND EARLY THURSDAY BEHIND THE SHORT WAVE DEPARTURE. IF RAIN PANS OUT TONIGHT...THIS IS A DISTINCT POSSIBILITY AS WINDS ARE LIGHT WITH RESIDUAL MOISTURE LINGERING. FOR NOW...HEDGED MVFR CONDITIONS FOR THOSE TWO LOCATIONS FOR THIS POSSIBILITY. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...MJ SHORT TERM...CHENARD LONG TERM...08 AVIATION...MJ
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1008 AM CDT WED AUG 20 2014 .UPDATE... ISSUED AT 1008 AM CDT WED AUG 20 2014 CURRENT CONVECTION IN EASTERN NEBRASKA CONTINUES TO FILTER NORTHEASTWARD INTO PARTS OF NORTHWEST IA...EXTREME NORTHEAST NEB AND FAR SOUTHEAST SD THIS MORNING. THIS ACTIVITY IS ASSOCIATED WITH A 700MB WAVE...MARKED BY DECENT MID LEVEL FRONTOGENESIS AND STRONG MID LEVEL SPEED CONVERGENCE IN THAT AREA. SIGNALS BASED OFF OF THE 12Z NAM CONTINUE TO POINT AT A GRADUAL WEAKENING OF THESE FEATURES INTO MIDDAY...ALBEIT THERE ARE SOME INDICATIONS THAT THE MID LEVEL CONVERGENCE MAY MAKE IT ALL THE WAY TOWARD THE IA GREAT LAKES AREA AND STORM LAKE EARLY THIS AFTERNOON. SO THAT WILL NEED MONITORED TO SEE IF WE NEED TO INCREASE AFTERNOON POPS IN THAT AREA. THIS CONVECTION HAS REALLY FOULED UP THE LOW LEVEL AND SURFACE BOUNDARIES THIS MORNING. AT THIS TIME...IT APPEARS THAT THE CURRENT POSITION OF THE MAIN WARM FRONT IS STILL AROUND THE OMAHA AREA PUSHED SOUTHWARD BY THE RAINFALL. THE VARIOUS SHORTER RANGE MODELS ARE ALL OVER THE MAP IN HOW THEY LIFT THE FRONT...OR FRONTS... NORTHWARD THIS AFTERNOON AND EVENING. FURTHERMORE...THE NEW 12Z NAM HAS THE MAIN SHORT WAVE LIFTING OUT MUCH FURTHER TO THE NORTHWEST AND NORTH OF OUR FORECAST AREA TONIGHT...WITH A LOBE OF UPPER QG FORCING ARCING SOUTHWARD INTO OUR AREA THIS EVENING FROM THE PARENT SHORT WAVE TO OUR NORTH. SO FOR TONIGHT...THE ACTUAL WAVE MAY NOT BE MUCH OF A PLAYER FOR OUR FORECAST AREA. IN ADDITION...THE SURFACE WIND SHIFT TO THE WEST DOES NOT TAKE PLACE UNTIL TOMORROW. SO ANY TORNADIC ACTIVITY WILL LIKELY HAVE TO BE CONFINED TO NEAR THE NORTHWARD LIFTING WARM FRONT WHICH IS DIFFICULT TO PROG. FOLLOWING THE 4KM NAM AND HRRR AS GUIDES SINCE THEY ARE VERY CLOSE... IT APPEARS THAT ONE WARM FRONTAL BOUNDARY SCOOTS NORTHWARD WITH THE WARM AIR ADVECTION TODAY...EVENTUALLY SETTING UP AND STALLING GENERALLY FROM CENTRAL ND...TO NORTHEAST SD...AND DOWN TO JUST NORTH OF MARSHALL MN THIS EVENING. BUT THERE IS A SECOND BOUNDARY AS WAS SHOWN YESTERDAY GENERALLY EXTENDING FROM LOW PRESSURE IN WEST CENTRAL SD...TO NEAR CHAMBERLAIN AND SIOUX CITY FROM 21Z TO 03Z TODAY...THEN WASHES OUT LIKELY DUE TO THE SHORT WAVE PASSAGE TO OUR NORTHWEST. AFTER ALL OF THIS MORNING AND MIDDAY CONVECTION IN OUR SOUTHERN ZONES...WORRIED THAT THE SOUTHERN PART OF THIS SECOND WARM FRONT IN OUR SOUTHERN ZONES COULD BE CAPPED OFF INTO THE EARLY EVENING HOURS. THIS WOULD INCLUDE THE SIOUX CITY... YANKTON AND STORM LAKE AREAS. BUT FURTHER WEST TOWARD CENTRAL SD WHERE STRONGER HEATING SHOULD OCCUR...THAT AREA COULD HAVE ENOUGH LOW LEVEL CURVATURE TO SPAWN ISOLATED TORNADOES THIS EVENING... AROUND THE CHAMBERLAIN AND MITCHELL AREAS...POSSIBLY EXTENDING NORTHWARD THEN THROUGH THE EVENING CLOSER TO HIGHWAY 14 IN OUR SOUTH DAKOTA ZONES. THE AFOREMENTIONED SURFACE LOW TO THE WEST SHOULD ALSO AID IN LOW LEVEL CURVATURE IN OUR FAR WESTERN ZONES. SO THIS APPEARS TO BE THE AREA RIGHT NOW FOR THE BEST CHANCE FOR TORNADIC ACTIVITY THIS EVENING...AT LEAST WITH THE CURRENT ANALYSIS. A BROADER RISK OF SEVERE WEATHER IS CERTAINLY WARRANTED THROUGH THE FORECAST AREA INTO THE MIDDLE OF THE NIGHT ALONG THE UPPER QG FORCING LOBE WHICH WAS MENTIONED ABOVE. WILL CONTINUE TO MONITOR FOR THE LATEST TRENDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 341 AM CDT WED AUG 20 2014 SHOWERS AND THUNDERSTORMS EXPANDING THIS MORNING ALONG AND JUST SOUTH OF THE MISSOURI RIVER IN AN AREA OF INCREASING ISENTROPIC LIFT ON THE EDGE OF THE LOW LEVEL JET. THESE STORMS SHOULD GENERALLY REMAIN SUB SEVERE WITH BRIEF HEAVY RAIN...ALTHOUGH A FEW MARGINALLY SEVERE HAIL REPORTS ARE POSSIBLE. NOT REALLY A STRAIGHT FORWARD FORECAST AS WE GO THROUGH THE THE DAY TODAY INTO TONIGHT REGARDING CONVECTIVE EVOLUTION. THOUGHT IS THE ELEVATED CONVECTION THIS MORNING WILL GENERALLY BEGIN TO WEAKEN AND DISSIPATE BY MID MORNING AS THE AREA OF ISENTROPIC LIFT MOVES NORTH INTO DRIER AIR AND WE HAVE THE DIURNAL WEAKENING OF THE LOW LEVEL JET. THIS IS SUPPORTED BY A MAJORITY OF THE HI RES GUIDANCE. STILL SHOULD BE QUITE A BIT OF MID LEVEL CLOUDINESS THAT STICKS AROUND THROUGH THE DAY...AND POSSIBLY AN ISOLATED ELEVATED SHOWER OR STORM. BUT GENERALLY THINKING THE DAY ENDS UP MAINLY DRY...UNTIL WE SEE A REGENERATION THIS EVENING INTO THE OVERNIGHT...WHICH WILL BE DISCUSSED BELOW. HIGHS TODAY TRICKY AS WELL GIVEN CLOUD COVER UNCERTAINTY. WILL CONTINUE TO GO MIDDLE GROUND FOR HIGHS...WITH THE CLOUD COVER...HIGH BOUNDARY LAYER MOISTURE...AND SOUTHEASTERLY WINDS LIMITING MIXING. STILL SHOULD SEE MID TO UPPER 80S...WHICH COMBINED WITH THE HIGH DEWPOINTS WILL RESULT IN HEAT INDICES FROM THE UPPER 80S TO MID 90S...HIGHEST ALONG THE MISSOURI RIVER. MAIN FOCUS OF THIS FORECAST IS ON SEVERE WEATHER CHANCES THIS AFTERNOON AND TONIGHT. THROUGH THE DAY A WARM FRONT WILL WORK ITS WAY NORTH...SETTING UP SOMEWHERE ACROSS THE CWA BY THIS EVENING. THIS WILL ENHANCE LOW LEVEL SHEAR...WITH 0 TO 1 KM SHEAR EXPECTED TO BE 15 TO 20 KTS. GOOD TURNING OF THE WINDS WITH HEIGHT WILL ALSO RESULT IN DEEP LAYER SHEAR OF 40 OR MORE KTS...SUFFICIENT FOR SUPERCELLS. MLCAPE SHOULD BE PLENTIFUL AS WELL WITH MOST LOW LEVELS AND STEEP LAPSE RATES ALOFT RESULTING IN VALUES OF 2000 TO 3000 J/KG. AM CONCERNED ABOUT LOW LEVEL LAPSE RATES AND STABILITY THOUGH. MODEL SOUNDINGS SHOW A PRETTY GOOD CAP IN PLACE FOR MUCH OF THE DAY. LOW LEVEL FORCING DOES NOT SEEM STRONG ENOUGH TO OVERCOME THIS FOR MOST OF THE DAY...WHICH SHOULD KEEP SURFACE BASED CONVECTION AT BAY. THE UPPER WAVE WILL PASS BY TO OUR NORTH THIS AFTERNOON AND EVENING...BUT SHOULD PASS TOO FAR NORTH TO AID TOO MUCH IN CONVECTIVE DEVELOPMENT...AS 700 AND 500 MB HEIGHT FALLS ARE MINIMAL TO NON EXISTENT. THUS CONVECTIVE DEVELOPMENT WILL RELY MAINLY ON FORCING FROM THE WEST TO EAST MOVING COLD FRONT AND THE INCREASING LOW LEVEL JET TOWARDS 0Z. PREFER TIMING AND PLACEMENT CLOSE TO THE 06Z 4KM NAM...AND 4KM NMMB. THIS WOULD GIVEN CONVECTIVE INITIATION ACROSS CENTRAL SOUTH DAKOTA...WITH STORMS MOVING TOWARDS CHAMBERLAIN AND HURON BETWEEN 6PM AND 9PM. GIVEN THE AMPLE CAPE...STORMS SHOULD BE ABLE TO THEN PROGRESS ACROSS MUCH OF THE CWA...APPROACHING INTERSTATE 29 AFTER 10 PM AND THE EASTERN CWA AFTER MIDNIGHT. GIVEN THE GOOD MODEL AGREEMENT WENT WITH LIKELY POPS MOST AREAS...STAYED SHY OF GOING CATEGORICAL GIVEN THAT THERE IS STILL A CHANCE THE STORMS PEEL OFF TO THE NORTH CLOSER TO THE BETTER UPPER SUPPORT. IN GENERAL THE SPC SLIGHT RISK AND PROBABILITIES SEEM GOOD. GIVEN THE STEEP LAPSE RATES ALOFT AND GOOD SHEAR...LARGE HAIL OF TENNIS BALL SIZE WILL INITIALLY BE A THREAT. THIS VERY LARGE HAIL THREAT SHOULD MAINLY BE CLOSER TO WHERE STORMS INITIATE...LIKELY THE VICINITY OF THE JAMES RIVER OR WEST. AS STORMS MOVE EAST...SOME LARGE HAIL WILL STILL BE POSSIBLE...BUT THE STRONG WIND THREAT SHOULD ALSO INCREASE. TORNADO THREAT IS UNCERTAIN GIVEN THE UNCERTAINTY ON WHETHER STORMS BECOME NEAR SURFACE BASED. BUT GIVEN THE SHEAR MENTIONED ABOVE...CAN NOT RULE OUT A TORNADO OR TWO...GREATEST THREAT AGAIN APPEARS TO BE WEST OF INTERSTATE 29...PROBABLY EVEN ALONG OR JUST WEST OF THE JAMES RIVER. HEAVY RAIN WILL ALSO BE LIKELY IN ANY STORMS...WITH PWATS UP TO 3 STANDARD DEVIATIONS ABOVE NORMAL. STORMS SHOULD BE MOVING ENOUGH TO PREVENT A BIG FLASH FLOOD RISK...ALTHOUGH LOCALIZED FLOODING WOULD BE POSSIBLE IN THE HEAVIER STORMS. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 341 AM CDT WED AUG 20 2014 THURSDAY LOOKS WARM...DRY AND HUMID AS UPPER LEVEL RIDGING BUILDS ACROSS THE REGION. MAIN CONCERN ON THURSDAY WILL BE HEAT INDICES. WHILE NOT QUITE TO ADVISORY LEVELS COULD SEE SOME LOWER TO MIDDLE 90S FOR HEAT INDICES WHICH WILL FEEL PRETTY HOT GIVEN THE EXPECTED 5 TO 10 MPH WIND. THURSDAY NIGHT INTO FRIDAY WILL SEE A TROUGH OF LOW PRESSURE SWING ONTO THE PLAINS WHICH WILL BRING A GRADUALLY INCREASING THREAT FOR THUNDERSTORMS. JUST A SLIGHT CHANCE THURSDAY NIGHT THEN BECOMING MUCH MORE LIKELY LATE FRIDAY AFTERNOON AND FRIDAY NIGHT. ISOLATED SEVERE THUNDERSTORMS AS WELL AS HEAVY RAIN WILL BE A THREAT. FRIDAY LIKELY TO BE PRETTY WARM AND HUMID...ESPECIALLY THE SOUTHEAST HALF OF THE CWA. HEAT INDICES LIKELY 90 TO 95 IN THESE AREAS. IN THE OUTER PERIODS (SATURDAY THROUGH TUESDAY)...A FAIRLY STRONG TROUGH OF LOW PRESSURE IS FORECAST TO MOVE ACROSS THE NORTHERN PLAINS SATURDAY NIGHT INTO SUNDAY NIGHT. THE TIMING AND STRENGTH ARE FAIRLY CONSISTENT IN THE LATEST MODELS SO WILL CONTINUE WITH MID RANGE POPS DURING THIS TIME. ALSO LOOKS LIKE A DECENT CHANCE FOR SOME SPOTTY HEAVY RAINFALL AS THE UPPER LEVEL FLOW LOOKS TO POSSIBLY BECOME PARALLEL TO THE LOW LEVEL BOUNDARY...WHICH COULD SUPPORT SOME TRAINING OF THUNDERSTORMS. A LITTLE TOO FAR OUT TO REALLY NAIL THIS DOWN BUT SOMETHING TO WATCH FOR. AS THE WAVE PASSES COOLER AIR WILL SETTLE INTO THE AREA AND WITH CONTINUED TROUGHING TO THE WEST THE THREAT FOR SHOWERS AND THUNDERSTORMS...AS WELL AS ADDITIONAL CLOUD COVER...WILL ALSO CONTINUE. TEMPERATURE GUIDANCE IN THIS TIME FRAME IS ALREADY BELOW NORMAL AND SEE NO REAL REASON TO STRAY TOO FAR FROM THAT. STATISTICALLY A GOOD SIGNAL WITH THE GFS MEX GUIDANCE BELOW CLIMATOLOGICAL NORMALS AND THE ENSEMBLE MEAN OUTPUT COOLER YET WHICH IS USUALLY A BIG HINT TO STAY BELOW THE COLDER MEN TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1054 PM CDT TUE AUG 19 2014 VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. LIGHT AND VARIABLE WINDS WILL INCREASE FROM THE SOUTHEAST AROUND 10 TO 20 KT LATE TONIGHT INTO WEDNESDAY MORNING. SHOWERS AND THUNDERSTORMS MAY BUILD INTO THE MISSOURI VALLEY LATE TONIGHT THROUGH DAYBREAK...BUT ACTIVITY WILL LIKELY DIMINISH IN COVERAGE BY LATE MORNING THROUGH THE END OF THE TAF PERIOD. SHOWERS AND THUNDERSTORMS WILL REDEVELOP IN OUR NORTHWESTERN COUNTIES AFTER 21Z...LIKELY CLOSER TO 00Z. SCATTERED THUNDERSTORMS SPREAD ACROSS THE REST OF THE AREA AFTER 00Z...WITH THE GREATEST POTENTIAL ALONG AND NORTH OF I-90. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...MJ SHORT TERM...CHENARD LONG TERM...08 AVIATION...
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
1031 PM EDT THU AUG 21 2014 .DISCUSSION...SMALL CLUSTER OF GENERALLY WEAK THUNDERSTORMS HAS MOVED SE OUT OF THE FORECAST AREA...AFFECTING MAINLY SW VA AND THE NE TIP OF TN. RAP MODEL SEEMS TOO AGRESSIVE IN DEVELOPING MORE SHOWERS AND STORMS DURING THE EARLY MORNING HOURS. FAVORING THE DRIER NAM AND HRR MODELS...WHICH DON`T SHOW ANY MORE CONVECTION UNTIL POSSIBLY TOWARD OR AFTER 12Z FRIDAY IN SW VA. THUS...OPTED TO DROP POPS FOR THE REMAINDER OF THE FORECAST AREA OVERNIGHT. ADDED PATCHY FOG WHERE THE SHOWERS AND STORMS MOVED ACROSS... AND TWEAKED A FEW TEMPS THAT WERE RAIN COOLED. NO OTHER CHANGES. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 71 96 73 96 / 20 20 20 20 KNOXVILLE MCGHEE TYSON AIRPORT, TN 70 92 73 93 / 30 30 30 40 OAK RIDGE, TN 69 92 72 93 / 30 30 30 40 TRI CITIES AIRPORT, TN 65 89 68 90 / 60 50 50 40 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
500 AM CDT WED AUG 20 2014 .UPDATE... 12Z TAF DISCUSSION. && .AVIATION... PATCHY FOG WILL BRING BRIEF MVFR/IFR VIS TO CKV/CSV EARLY THIS MORNING. OTHERWISE...SATELLITE IMAGERY SHOWS SCT CUMULUS THIS MORNING WHICH WILL INCREASE IN COVERAGE BY AFTERNOON...WITH VCTS AT CSV AFTER 18Z. HRRR MODEL RUNS ARE RATHER AGGRESSIVE WITH PRECIP ACROSS THE MID STATE LATER TODAY...SO CANNOT COMPLETELY RULED OUT A -SHRA/-TSRA AT CKV/BNA EITHER. LIGHT SOUTHWEST TO WEST WINDS ARE ANTICIPATED TODAY WITH SPEEDS 5-10 KTS. SHAMBURGER && .PREV DISCUSSION... /ISSUED 244 AM CDT WED AUG 20 2014/ DISCUSSION... ..TEMPS TO HEAT UP OVER THE NEXT SEVERAL DAYS... SHORT WAVE EVIDENT IN WIND FIELD AND SOMEWHAT IN VORTICITY PATTERN WORKING THROUGH EASTERN KENTUCKY DOWN THROUGH EASTERN TENNESSEE WITH SHOWERS AND A FEW THUNDERSTORMS ACROSS EASTERN KENTUCKY TRYING TO EXTEND DOWN ALONG TENNESSEE/KENTUCKY BORDER EAST OF MY CWA. NORTHWEST FLOW WILL CONTINUE DURING THE DAY AS WARM/HOT UPPER LEVEL ANTICYCLONE BEGINS BUILDING IN THIS DIRECTION FROM SOUTHERN PLAINS. MODELS ARE KEEPING SMALL POPS IN FOR TODAY ACROSS ALL OF MIDDLE TENNESSEE WITH A LITTLE BETTER CHANCE OVER EASTERN AREAS AND PLATEAU. HAVE LOW CONFIDENCE THAT WE ARE GOING TO SEE MUCH MORE THAN ISOLATED CONVECTION TODAY INTO THIS EVENING BUT DID INCLUDE A SMALL POP IN FORECAST FOR TODAY AND EVENING. AS UPPER RIDGE APPROACHES SUBSIDENCE GETS UNDERWAY WITH GOOD ADIABATIC COMPRESSION WHICH WILL ACT TO DRY OUT TROPOSPHERE OVER THE NEXT SEVERAL DAYS WHICH MEANS LITTLE OR NO CHANCE FOR RAIN. ADIABATIC COMPRESSION WILL ALSO HEAT TEMPS UP WELL INTO THE 90S LATTER PART OF THIS WORK WEEK...OVER THE WEEKEND INTO THE FIRST OF NEXT WEEK. CLIMATE...THE HOTTEST TEMPERATURE SO FAR THIS SUMMER IN NASHVILLE HAS BEEN 97 DEGREES ON AUGUST 6TH. LAST SUMMER (2013) THE HOTTEST TEMPERATURE WAS 97 DEGREES ON JULY 17TH. HOTTEST SUMMER TEMPS SINCE 2000... 2013...97 JULY 17TH 2012...109 JUNE 29TH ALL-TIME RECORD HIGH FOR NASHVILLE 2011...102 AUGUST 3RD 2010...101 AUGUST 4TH 2009...95 JUNE 22ND AND JUNE 27TH 2008...97 JULY 21ST AND AUGUST 5TH 2007...106 AUGUST 16TH ALL-TIME RECORD HIGH FOR AUGUST 2006...100 JULY 19TH 2005...98 AUGUST 11TH...12TH AND 20TH 2004...94 JULY 13TH 2003...94 JULY 28TH 2002...97 AUGUST 5TH 2001...95 JULY 8TH 2000...100...AUGUST 17TH && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 55
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
ISSUED BY NATIONAL WEATHER SERVICE BROWNSVILLE TX 1251 PM CDT WED AUG 20 2014 .AVIATION...SOUTHEAST WINDS WILL CONTINUE TO BE STRONG AND GUSTY THIS AFTERNOON ACROSS THE TERMINALS WITH VFR CONDITIONS. WINDS WILL GRADUALLY LOWER TONIGHT TO AROUND 10 TO 15 KNOTS BEFORE INCREASING INTO THURSDAY. MVFR STRATUS WILL BE REDEVELOP IN THE EARLY MORNING HOURS BUT WILL BEGIN TO BREAK AS SE WINDS BEGIN TO INCREASE AFTER 15Z THURSDAY. && .PREV DISCUSSION... /ISSUED ISSUED BY NATIONAL WEATHER SERVICE BROWNSVILLE TX/ DISCUSSION...UPPER LEVEL STORM SYSTEM CONTINUES TO SLOWLY WEAKEN JUST SOUTHEAST OF THE AREA. 15/16Z SURFACE OBSERVATIONS AND MORNING SOUNDINGS CONTINUE TO SUPPORT THE IDEA OF SEABREEZE SHOWERS/THUNDERSTORMS BUILDING UP IN THE AFTERNOON ALONG THE COASTAL BEND AND MOVING INTO ROUGHLY THE EASTERN QUARTER OF THE AREA...WHICH WORKS WELL WITH LAST FEW HOURS OF HRRR RUNS ON COVERAGE AND INTENSITY. TEMPERATURES AND WINDS ALSO LOOK ON TRACK...NO SHORT TERM CHANGES PLANNED. /68-JGG/ PREV DISCUSSION... /ISSUED 624 AM CDT WED AUG 20 2014/ AVIATION... MVFR CONDITIONS HAVE BROKEN OUT ACROSS THE I-35 CORRIDOR THIS MORNING. EXPECT THIS TO CONTINUE THROUGH ABOUT 17Z BEFORE VFR CIGS RETURN. WITH THE MOIST SOUTHERLY FLOW FROM THE GULF OF MEXICO CONTINUING WE EXPECT MVFR STRATUS TO RETURN TONIGHT AROUND 08Z. DEL RIO MAY SEE A COUPLE HOURS OF MVFR CIGS THIS MORNING...SO HAVE MAINTAINED THE TEMPO GROUP FROM 13Z TO 15Z FROM PREVIOUS TAF PACKAGES. WITH THE EXCEPTION OF THIS MORNING DRT WILL BE VFR THROUGH THE PERIOD. WINDS WILL CONTINUE TO BE STRONG AND GUSTY AT TIMES. SOUTH TO SOUTHEAST WINDS AT 10-15 KNOTS CAN BE EXPECTED THIS MORNING GUSTING AT TIMES TO 20 KNOTS THIS AFTERNOON. WINDS CALM SLIGHTLY OVERNIGHT...BACK DOWN TO AROUND 10 KNOTS...BEFORE PICKING UP AGAIN ON THURSDAY. PREV DISCUSSION... /ISSUED 311 AM CDT WED AUG 20 2014/ SHORT TERM (TODAY THROUGH THURSDAY)... SHOWERS AND THUNDERSTORMS HAVE DISSIPATED ACROSS THE WESTERN COUNTIES AND AM NOT EXPECTING MUCH IN THE WAY OF ADDITIONAL ACTIVITY. THE UPPER TOUGH/SHEAR AXIS RESPONSIBLE FOR THE 48 HOURS OF ACTIVITY HAS WEAKENED AND LIFTED TO THE NORTHEAST. THERE IS A SLIGHT CHANCE OF SEA BREEZE SHOWERS AND THUNDERSTORMS ACROSS THE COASTAL PLAINS COUNTIES THIS AFTERNOON. PW VALUES THEN DROP OFF AND WILL KEEP A DRY FORECAST ACROSS ALL OF SOUTH CENTRAL TEXAS ON THURSDAY. HIGHS TODAY AND THURSDAY WILL BE PERSISTENT...IN THE UPPER 90S TO NEAR 100 DEGREES FOR MUCH OF THE AREA. LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)... A MOSTLY DRY FORECAST WILL CONTINUE THROUGH SUNDAY. MOISTURE WILL REMAIN RATHER SPARCE AND THIS SHOULD LIMIT THE ACTIVITY. CANT COMPLETELY RULE OUT A STRAY SHOWER ON ANY GIVEN AFTERNOON...BUT THE CHANCES WERE TOO LOW TO MENTION AT THIS TIME. PW VALUES INCREASE TO NEAR 2 INCHES ACROSS THE SOUTHEASTERN COUNTIES ON MONDAY AND THIS SHOULD BE SUFFICIENT TO WARRANT A MENTION OF THUNDERSTORMS IN THIS AREA MONDAY. MODELS ARE SHOWING THIS INCREASE IN MOISTURE TO BE SHORT LIVED WITH PW VALUES RETURNING TO BELOW 1.8 INCHES TUESDAY. TEMPERATURES IN THE EXTENDED WILL CONTINUE TO BE PERSISTENT WITH HIGHS IN THE UPPER 90S TO NEAR 100 DEGREES AND LOWS IN THE MIDDLE TO UPPER 70S ACROSS MUCH OF THE AREA. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM AUSTIN BERGSTROM INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM NEW BRAUNFELS MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM BURNET MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM DEL RIO INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM GEORGETOWN MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM HONDO MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM SAN MARCOS MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM LA GRANGE - FAYETTE REGIONAL MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM SAN ANTONIO INTL AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM STINSON MUNI AIRPORT MMM MMM MMM MMM MMM / MMM MMM MMM MMM MMM && .EWX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE/AVIATION...99 SYNOPTIC/GRIDS...99
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
119 PM EDT WED AUG 20 2014 .SYNOPSIS... A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE REGION EACH DAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 955 AM EDT WEDNESDAY... BAND OF DEEP CONVECTION CONTINUES TO PUSH SE OUT OF THE MOUNTAIN EMPIRE REGION INTO THE BLUE RIDGE ATTM AND EXPECT THIS AXIS TO PERSIST UNTIL PERHAPS TOPPING THE FOOTHILLS IN THE NEXT HOUR OR SO. THIS DESPITE LACK OF INSTABILITY AHEAD OF THE SHRA/TSRA COMPLEX AS FEED OF BETTER CAPES AND THETA-E ADVECTION OFF TO THE WEST PROVIDING SUPPORT. THIS AHEAD OF THE MID LEVEL SHORTWAVE TROUGH THAT IS CURRENTLY APPROACHING THE WESTERN SLOPES AND ALONG THE RESIDUAL SURFACE FRONT THAT HAS BACKDOORED SW INTO SW VA EARLY THIS MORNING. ALTHOUGH EXPECTING THIS PRECIP TO FADE...COMBINATION OF EARLY CLOUDS/SHRA OVER THE WEST AND LINGERING FOG/STRATUS IN THE EASTERN WEDGE WILL MAKE THINGS TRICKY IN REGARDS TO POSSIBLE RENEWED AFTERNOON CONVECTION. MOST EARLIER GUIDANCE AND CURRENT SHORT TERM SOLUTIONS WANT TO REDEVELOP TSRA ALONG THE BLUE RIDGE BEFORE SLIDING THIS EAST INTO EARLY EVENING AS THE TROUGH AXIS LIFTS NE. HOWEVER THE LATEST HRRR ONLY SHOWS ISOLATED COVERAGE BLUE RIDGE AFTER CURRENT SHRA FIZZLES WHILE THE 12Z NAM SLOWER IN HOLDING OFF MOST NEW CONVECTION UNTIL LATE OR EARLY EVENING EAST WITH SOME WEAK CAPPING ALOFT UNDER RESIDUAL CLOUDS IN THE WAKE OF THE CURRENT COVERAGE. THUS HAVE ADJUSTED POPS DOWN SOME IN THE FAR WEST AND TRIMMED LIKELYS DOWN BLUE RIDGE BEHIND THE ONGOING COVERAGE BEFORE BEEFING UP OUT EAST MID/LATE AFTERNOON AS CAPES RECOVER LATE TO 1-2K J/KG. HIGH TEMPS WILL AGAIN GET OFF TO A SLOW START IN SPOTS WITH LATE DAY HIGHS MOST SPOTS PENDING ADDED SHRA/TSRA WITH PERHAPS THE FAR WEST BEING THE WARMEST WITH MORE SUN EARLIER BEHIND THE CURRENT COVERAGE. PREVIOUS VALID DISCUSSION... AN UPPER LEVEL TROUGH OF LOW PRESSURE IS MOVING THROUGH THE GREAT LAKES WITH LOBE OF VORTICITY TRAILING SOUTH INTO THE OHIO VALLEY. THIS FEATURE HAS RESULTED IN A PERSISTENT AREA OF LIFT ASSOCIATED WITH SHOWERS AND THUNDERSTORMS. AS OF 08Z/4AM...NUMEROUS SHOWERS AND STORMS WERE OCCURRING FROM WESTERN PA INTO EASTERN OHIO AND NORTHEAST KY. OUTFLOW FROM THIS COMPLEX OF THUNDERSTORMS IS EXPECTED TO MAKE ITS WAY OVER THE MOUNTAINS TODAY. MODELS DO NOT SEEM OVERLY CONFIDENT THIS OUTFLOW WILL MAKE IT OVER THE MOUNTAINS...INDICATING WEAKENING AND A GRADUAL DEMISE OF ACTIVITY. MATTER OF FACT THE SYNOPTIC MODELS DON`T PRODUCE MUCH IN THE WAY OF RAINFALL AT ALL ACROSS OUR CWA...MOS POPS GENERALLY LESS THAN 40 PERCENT. ATTM PREFER NOT TO IGNORE THE OBVIOUS...WHICH IS A MODEST LOOKING UPPER LEVEL TROF...ASSOCIATED WITH A HEALTHY LOOKING AREA OF SHRA/TSRA...THE OUTFLOW OF WHICH SHOULD PASS THROUGH OUR FORECAST AREA TODAY. THE ONLY THING THAT KEPT ME FROM GOING WITH CATEGORICAL POPS IS THE POTENTIAL TIMING OF THE ACTIVITY AS IT CROSSES THE MOUNTAINS. BASED ON CURRENT PROGRESSION...SHOWERS WILL MOVE INTO THE WV MOUNTAINS DURING THE MORNING...THEN PROGRESS EAST REACHING THE BLUE RIDGE TOWARD NOON...THEN EAST OF THE MTNS EARLY THIS AFTERNOON. THIS EARLIER SORT OF TIMING SUGGESTS DEBRIS CLOUDS WILL OVERSPREAD THE CWA EARLY AND LIMIT FULL INSOLATION THUS LIMITING INSTABILITY. THAT SAID...THINK AREA OF SHOWERS WITH EMBEDDED THUNDER WILL CROSS THE FORECAST AREA...BUT IN A WEAKENED STATE. GREATEST COVERAGE WILL BE FROM THE VIRGINIAS NORTHWARD CLOSER TO THE UPPER SUPPORT FROM THE SHORT WAVE TROUGH...THE STRONGER DYNAMIC LIFT MOVING FROM THE OHIO VALLEY INTO PA/NY. HAVE PLACED THE HIGHEST POPS ACROSS WV/VA CLOSER TO THE SUPPORT FROM THE UPPER TROF...AND WHERE THE OUTFLOW WILL HAVE THE BEST CHANCE OF MAKING IT OVER THE MOUNTAINS AND HELP FOCUS RENEWED DEEP CONVECTION. FARTHER SOUTH...FROM THE VA/NC BORDER SOUTHWARD...COVERAGE WILL BE LESS AND MORE SCATTERED IN NATURE. WITH LESS COVERAGE COMES THE OPPORTUNITY FOR MORE SUN. MORE SUN SUGGESTS WARMER TEMPERATURES...AND WARMER TEMEPERATURES WILL YIELD GREATER INSTABILITY PROVIDING STRONGER UPDRAFTS. AS SUCH CAN`T RULE OUT A STRONG PULSE STORM OR TWO...ESPECIALLY WHERE MORE SUN MATERIALIZES. WENT BLO MOS GUIDANCE FOR TEMPERATURES ACROSS THE VIRGINIAS WHERE MORE CLOUD COVER IS ANTICIPATED TODAY. THE WARMEST TEMPERATURES WILL BE ACROSS NORTH CAROLINA WHERE MORE SUN IS ANTICIPATED. PASSAGE OF THE UPPER TROUGH WILL BRING AN END TO MOST OF THE STORM ACTIVITY THIS EVENING...FOLLOWED BY ANOTHER FOGGY NIGHT WITH AREAS OF FOG AND PATCHY DENSE FOG DEVELOPING ACROSS THE FORECAST AREA. IF SKIES CAN COMPLETELY CLEAR...THIS WOULD BE MOST IDEAL FOR RADIATION FOG. THERE WERE SEVERAL REPORTS IN THE NEW RIVER VALLEY WITH DENSE FOG EARLY WEDNESDAY MORNING. THINK IT WILL BE A REPEAT AGAIN EARLY THURSDAY MORNING. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... AS OF 330 AM WEDNESDAY... THE REGION WILL REMAIN IN AN ACTIVE WEATHER PATTERN DURING THIS PORTION OF THE FORECAST. A STRONG UPPER HIGH PRESSURE WILL BE SITUATED ACROSS THE MID-MISSISSIPPI VALLEY. A DEEPENING UPPER LOW/TROUGH WILL BE POSITIONED OFF THE COAST OF NEW ENGLAND. OUR AREA OF THE COUNTRY WILL BE SANDWICHED BETWEEN THE TWO WITHIN NW-SE ORIENTED MID-LEVEL BAROCLINIC ZONE...WITH AN ASSOCIATED SURFACE BACKDOOR COLD FRONT EITHER OVER...OR VERY CLOSE TO THE REGION BY THE START OF THE WEEKEND. THE ABOVE SCENARIO POINTS TOWARD A PERIOD WITH AT LEAST SCATTERED SHOWERS IN THE FORECAST EACH DAY AND NIGHT...AND SOME AFTERNOON AND EVENING STORMS. WHAT IS A LITTLE HARDER TO NAIL DOWN WILL BE THE WINDOWS OF OPPORTUNITY FOR LIKELY TO CATEGORICAL CHANCES OF PRECIPITATION IN ASSOCIATION WITH PERIODICAL UPPER LEVEL SHORTWAVE TROUGHS HEADING SOUTHEAST ALONG THIS BAROCLINIC ZONE AND THROUGH OUR REGION. EACH MODEL SEEMS TO HAVE A DIFFERENT TAKE ON TIMING AND TRACK. EYEBALLING A CONSENSUS OF THE GUIDANCE POINTS TOWARD THURSDAY AFTERNOON AND EVENING AS ONE POTENTIAL TIME THAT WOULD WARRANT HIGHER POPS...ESPECIALLY ACROSS THE WESTERN AND NORTHERN PARTS OF THE REGION. ANOTHER OPPORTUNITY MAY BE FRIDAY NIGHT ACROSS MAINLY NORTHERN AND EASTERN PARTS OF THE AREA. FINALLY...SATURDAY NIGHT MAY PROVE TO BE A THIRD OPPORTUNITY FOR ALL OF THE REGION...ESPECIALLY CENTRAL AND WESTERN PORTIONS. AT THIS TIME...CONFIDENCE IS NOT THERE TO OFFER A CATEGORICAL...75 PERCENT OR HIGHER...CHANCE OF PRECIPITATION FOR ANY ONE OF THE THREE SCENARIOS LISTED ABOVE. HOWEVER...WILL CONTINUE...OR ADD...A FORECAST OF LIKELY POPS TO THE FIRST AND SECOND SCENARIOS. FOR THE THIRD SCENARIO...WILL OFFER A FORECAST JUST SHY OF LIKELY POPS. TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO GRADUALLY COOL AS THE BAROCLINIC ZONE MAKES PROGRESS WESTWARD. THE COMBINATION OF MORE CLOUD COVER AND MORE PRECIPITATION...ALONG WITH LOWER HEIGHTS WILL CONTRIBUTE TO THIS. BY SATURDAY...THE SURFACE COLD FRONT MAY BE BISECTING THE REGION FROM NW-SE...THUS YIELDING NOTABLY COOLER TEMPERATURES AT LEAST FOR THE CENTRAL AND NORTHEAST PARTS OF THE AREA. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 130 PM EDT TUESDAY... THE WEEKEND THROUGH EARLY NEXT WEEK WILL BE CHARACTERIZED BY THE BATTLE BETWEEN LARGE UPPER RIDGE TO OUR WEST TRYING TO BUILD INTO SOUTHERN APPALACHIANS...WHILE TROUGH OFF NEW ENGLAND COAST DEEPENS WHILE CLOSING OFF AND CONTINUES TO APPEAR THAT IT WILL SET UP CLOSE ENOUGH TO COAST TO PUSH BACK DOOR FRONT THROUGH AND WELL SOUTH OF THE AREA THROUGH THE WEEKEND...BEFORE LIKELY WEAKENING AND ALLOWING MORE INFLUENCE OF THE RIDGE TO BE FELT BY TUES...ESPECIALLY ACROSS WESTERN PARTS OF THE AREA IF WEAK/SHALLOW BOUNDARY LAYER WEDGE IS IN PLACE EARLY IN THE DAY BEFORE MIXING OUT OVER THE EAST. WHILE SURFACE WEDGE FRONT MAY BE WELL TO THE SOUTH DURING MUCH OF THIS PERIOD...WITH STRONGEST SOUTHWARD PUSH ON SATURDAY...THE 850 BOUNDARY AND MOST LIKELY TRACK FOR UPPER S/WV ENERGY FROM THE NW IS LIKELY TO BE RIGHT OVER THE BLACKSBURG FORECAST AREA...AND THUS GOOD CHANCE FOR SHOWERS/THUNDERSTORMS THROUGH THIS ENTIRE PERIOD. TIMING MOST LIKELY WINDOWS REMAINS TRICKY...AS MANY OF THESE WAVES ARE STRONGLY INFLUENCE BY CONVECTIVE COMPLEXES THAT WILL DEVELOP WELL UPSTREAM. LIKE THE TRENDS OVERALL THAT 12Z GFS IS TAKING...NOT ONLY WITH RETURN TO SHARPER AMPLITUDE PATTERN...BUT IDEA OF TWO DISTINCT WAVES HEADING FOR THE WESTERN PART OF OUR FORECAST AREA...ONE SATURDAY AND ANOTHER ONE SUNDAY. EXACT TIMES MAY HELP DETERMINE IF THERE WILL BE ENOUGH INSTABILITY...WHICH WOULD LIKELY BE LIMITED TO THE FAR WEST NEAR EDGE OF WEDGE BOUNDARY...BUT PERHAPS THE BIGGER CONCERN IS RAINFALL THAT IS LIKELY TO IMPACT THE SAME AREAS AT LEAST A COUPLE OF DAYS IN A ROW. THERE COULD BE ANOTHER WAVE FOR MONDAY...BUT AS RIDGE ATTEMPTS TO BUILD IN AND TROUGH TO THE EAST AND ASSOCIATED WEDGE WEAKEN WHAT MAY TEND TO OCCUR IS MORE DIURNAL POP-UP CONVECTION ALONG AND NEAR THE WESTERN PERIPHERY OF THE WEDGE BOUNDARY IN OUR WESTERN FORECAST AREA AS THE ATMOS DESTABILIZES MORE. BY TUESDAY THE SUPPORT TO KEEP WEDGE IN PLACE SHOULD BE WEAKENING AS TROUGH LIFTS AND SFC HIGH SHIFTS MORE EAST OF THE AREA...AND OVERALL IT LOOKS A LITTLE DRIER...BUT NOT SURE ALL POPS CAN BE REMOVED. GIVEN PATTERN WE`VE BEEN IN...REALLY DON`T HAVE CONFIDENCE TO DRY IT OUT OR WARM IT UP TOO FAST...SO WILL LEAN TOWARD STRONGER INFLUENCE OF THE WEDGE THROUGH THIS PERIOD AND BETTER CHANCES FOR PRECIP...WHICH WILL HELP STRENGTHEN THE WEDGE TOO. UNDERCUT EVEN COOLER ECMWF A LITTLE BIT FOR HIGHS...WITH A BIT MORE WARMING FOR TUESDAY. BUT IN THE FAR SOUTHWEST THINGS MAY BE ABLE TO WARM UP VERY QUICKLY A DAY OR TWO EARLIER THAN THIS IF THE WEDGE CAN BREAK AND SOME OF THE INFLUENCE OF THE BIG UPPER RIDGE CAN BE REALIZED. THIS WILL EVENTUALLY RESULT IN A SIGNIFICANT WARM UP FOR OUR ENTIRE AREA...BUT AM THINKING IT WILL NOT COME UNTIL MIDDLE OF NEXT WEEK. && .AVIATION /17Z WEDNESDAY THROUGH SUNDAY/... AS OF 100 PM EDT WEDNESDAY... ACTIVE AND VARIABLE WEATHER PATTERN CONTINUES THIS TAF PERIOD. EARLY CONVECTION WITHERED ON THE VINE AS IT MOVED OFF THE BLUE RIDGE AND HELPED STABILIZE THE ATMOSPHERE FOR A BIT. HOWEVER... LATEST ANALYSES INDICATE INSTABILITY IS RECOVERING AND MESO MODELS DO SHOW SOME CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. EASTERN AREAS ARE ON THE FRINGE OF HIGH PRESSURE WEDGING DOWN THE COAST WHERE THERE WAS EXTENSIVE LOW CLOUD COVER THIS MORNING. BELIEVE CONDITIONS WILL GENERALLY BE VFR BY ISSUANCE TIME AND WILL USE VICINITY TO COVER EXPECTED SHOWER/STORM DEVELOPMENT. CONDITIONS WILL DIP DOWN WITH ANY PRECIPITATION BUT FEEL A TEMPO GROUP WILL BE TOO HEAVY HANDED SO WILL LEAVE OUT MENTION OF LOWER CONDITIONS. TONIGHT WILL BE ANOTHER TOUGH CALL FOR FOG/LOW STRATUS DEVELOPMENT. INDICATIONS IN MESO RH FIELDS ARE THAT IFR/LIFR WILL BE LESS WIDESPREAD SO WILL TRY TO CONFINE LOW CONDITIONS TO A SMALLER PERIOD TOWARD DAYBREAK...JUST IN TIME TO MENTION SOME ADDITIONAL SHOWER ACTIVITY WITH THE NEXT WAVE OF ENERGY ENTERING FROM THE WEST. WINDS WILL NOT BE PROBLEMATIC FOR AVIATION PURPOSES THROUGH THIS TAF PERIOD. EXTENDED AVIATION... UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT FEW DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...SK NEAR TERM...JH/PM SHORT TERM...DS LONG TERM...SK AVIATION...MBS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1014 AM EDT WED AUG 20 2014 .SYNOPSIS... A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE REGION EACH DAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 955 AM EDT WEDNESDAY... BAND OF DEEP CONVECTION CONTINUES TO PUSH SE OUT OF THE MOUNTAIN EMPIRE REGION INTO THE BLUE RIDGE ATTM AND EXPECT THIS AXIS TO PERSIST UNTIL PERHAPS TOPPING THE FOOTHILLS IN THE NEXT HOUR OR SO. THIS DESPITE LACK OF INSTABILITY AHEAD OF THE SHRA/TSRA COMPLEX AS FEED OF BETTER CAPES AND THETA-E ADVECTION OFF TO THE WEST PROVIDING SUPPORT. THIS AHEAD OF THE MID LEVEL SHORTWAVE TROUGH THAT IS CURRENTLY APPROACHING THE WESTERN SLOPES AND ALONG THE RESIDUAL SURFACE FRONT THAT HAS BACKDOORED SW INTO SW VA EARLY THIS MORNING. ALTHOUGH EXPECTING THIS PRECIP TO FADE...COMBINATION OF EARLY CLOUDS/SHRA OVER THE WEST AND LINGERING FOG/STRATUS IN THE EASTERN WEDGE WILL MAKE THINGS TRICKY IN REGARDS TO POSSIBLE RENEWED AFTERNOON CONVECTION. MOST EARLIER GUIDANCE AND CURRENT SHORT TERM SOLUTIONS WANT TO REDEVELOP TSRA ALONG THE BLUE RIDGE BEFORE SLIDING THIS EAST INTO EARLY EVENING AS THE TROUGH AXIS LIFTS NE. HOWEVER THE LATEST HRRR ONLY SHOWS ISOLATED COVERAGE BLUE RIDGE AFTER CURRENT SHRA FIZZLES WHILE THE 12Z NAM SLOWER IN HOLDING OFF MOST NEW CONVECTION UNTIL LATE OR EARLY EVENING EAST WITH SOME WEAK CAPPING ALOFT UNDER RESIDUAL CLOUDS IN THE WAKE OF THE CURRENT COVERAGE. THUS HAVE ADJUSTED POPS DOWN SOME IN THE FAR WEST AND TRIMMED LIKELYS DOWN BLUE RIDGE BEHIND THE ONGOING COVERAGE BEFORE BEEFING UP OUT EAST MID/LATE AFTERNOON AS CAPES RECOVER LATE TO 1-2K J/KG. HIGH TEMPS WILL AGAIN GET OFF TO A SLOW START IN SPOTS WITH LATE DAY HIGHS MOST SPOTS PENDING ADDED SHRA/TSRA WITH PERHAPS THE FAR WEST BEING THE WARMEST WITH MORE SUN EARLIER BEHIND THE CURRENT COVERAGE. PREVIOUS VALID DISCUSSION... AN UPPER LEVEL TROUGH OF LOW PRESSURE IS MOVING THROUGH THE GREAT LAKES WITH LOBE OF VORTICITY TRAILING SOUTH INTO THE OHIO VALLEY. THIS FEATURE HAS RESULTED IN A PERSISTENT AREA OF LIFT ASSOCIATED WITH SHOWERS AND THUNDERSTORMS. AS OF 08Z/4AM...NUMEROUS SHOWERS AND STORMS WERE OCCURRING FROM WESTERN PA INTO EASTERN OHIO AND NORTHEAST KY. OUTFLOW FROM THIS COMPLEX OF THUNDERSTORMS IS EXPECTED TO MAKE ITS WAY OVER THE MOUNTAINS TODAY. MODELS DO NOT SEEM OVERLY CONFIDENT THIS OUTFLOW WILL MAKE IT OVER THE MOUNTAINS...INDICATING WEAKENING AND A GRADUAL DEMISE OF ACTIVITY. MATTER OF FACT THE SYNOPTIC MODELS DON`T PRODUCE MUCH IN THE WAY OF RAINFALL AT ALL ACROSS OUR CWA...MOS POPS GENERALLY LESS THAN 40 PERCENT. ATTM PREFER NOT TO IGNORE THE OBVIOUS...WHICH IS A MODEST LOOKING UPPER LEVEL TROF...ASSOCIATED WITH A HEALTHY LOOKING AREA OF SHRA/TSRA...THE OUTFLOW OF WHICH SHOULD PASS THROUGH OUR FORECAST AREA TODAY. THE ONLY THING THAT KEPT ME FROM GOING WITH CATEGORICAL POPS IS THE POTENTIAL TIMING OF THE ACTIVITY AS IT CROSSES THE MOUNTAINS. BASED ON CURRENT PROGRESSION...SHOWERS WILL MOVE INTO THE WV MOUNTAINS DURING THE MORNING...THEN PROGRESS EAST REACHING THE BLUE RIDGE TOWARD NOON...THEN EAST OF THE MTNS EARLY THIS AFTERNOON. THIS EARLIER SORT OF TIMING SUGGESTS DEBRIS CLOUDS WILL OVERSPREAD THE CWA EARLY AND LIMIT FULL INSOLATION THUS LIMITING INSTABILITY. THAT SAID...THINK AREA OF SHOWERS WITH EMBEDDED THUNDER WILL CROSS THE FORECAST AREA...BUT IN A WEAKENED STATE. GREATEST COVERAGE WILL BE FROM THE VIRGINIAS NORTHWARD CLOSER TO THE UPPER SUPPORT FROM THE SHORT WAVE TROUGH...THE STRONGER DYNAMIC LIFT MOVING FROM THE OHIO VALLEY INTO PA/NY. HAVE PLACED THE HIGHEST POPS ACROSS WV/VA CLOSER TO THE SUPPORT FROM THE UPPER TROF...AND WHERE THE OUTFLOW WILL HAVE THE BEST CHANCE OF MAKING IT OVER THE MOUNTAINS AND HELP FOCUS RENEWED DEEP CONVECTION. FARTHER SOUTH...FROM THE VA/NC BORDER SOUTHWARD...COVERAGE WILL BE LESS AND MORE SCATTERED IN NATURE. WITH LESS COVERAGE COMES THE OPPORTUNITY FOR MORE SUN. MORE SUN SUGGESTS WARMER TEMPERATURES...AND WARMER TEMEPERATURES WILL YIELD GREATER INSTABILITY PROVIDING STRONGER UPDRAFTS. AS SUCH CAN`T RULE OUT A STRONG PULSE STORM OR TWO...ESPECIALLY WHERE MORE SUN MATERIALIZES. WENT BLO MOS GUIDANCE FOR TEMPERATURES ACROSS THE VIRGINIAS WHERE MORE CLOUD COVER IS ANTICIPATED TODAY. THE WARMEST TEMPERATURES WILL BE ACROSS NORTH CAROLINA WHERE MORE SUN IS ANTICIPATED. PASSAGE OF THE UPPER TROUGH WILL BRING AN END TO MOST OF THE STORM ACTIVITY THIS EVENING...FOLLOWED BY ANOTHER FOGGY NIGHT WITH AREAS OF FOG AND PATCHY DENSE FOG DEVELOPING ACROSS THE FORECAST AREA. IF SKIES CAN COMPLETELY CLEAR...THIS WOULD BE MOST IDEAL FOR RADIATION FOG. THERE WERE SEVERAL REPORTS IN THE NEW RIVER VALLEY WITH DENSE FOG EARLY WEDNESDAY MORNING. THINK IT WILL BE A REPEAT AGAIN EARLY THURSDAY MORNING. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... AS OF 330 AM WEDNESDAY... THE REGION WILL REMAIN IN AN ACTIVE WEATHER PATTERN DURING THIS PORTION OF THE FORECAST. A STRONG UPPER HIGH PRESSURE WILL BE SITUATED ACROSS THE MID-MISSISSIPPI VALLEY. A DEEPENING UPPER LOW/TROUGH WILL BE POSITIONED OFF THE COAST OF NEW ENGLAND. OUR AREA OF THE COUNTRY WILL BE SANDWICHED BETWEEN THE TWO WITHIN NW-SE ORIENTED MID-LEVEL BAROCLINIC ZONE...WITH AN ASSOCIATED SURFACE BACKDOOR COLD FRONT EITHER OVER...OR VERY CLOSE TO THE REGION BY THE START OF THE WEEKEND. THE ABOVE SCENARIO POINTS TOWARD A PERIOD WITH AT LEAST SCATTERED SHOWERS IN THE FORECAST EACH DAY AND NIGHT...AND SOME AFTERNOON AND EVENING STORMS. WHAT IS A LITTLE HARDER TO NAIL DOWN WILL BE THE WINDOWS OF OPPORTUNITY FOR LIKELY TO CATEGORICAL CHANCES OF PRECIPITATION IN ASSOCIATION WITH PERIODICAL UPPER LEVEL SHORTWAVE TROUGHS HEADING SOUTHEAST ALONG THIS BAROCLINIC ZONE AND THROUGH OUR REGION. EACH MODEL SEEMS TO HAVE A DIFFERENT TAKE ON TIMING AND TRACK. EYEBALLING A CONSENSUS OF THE GUIDANCE POINTS TOWARD THURSDAY AFTERNOON AND EVENING AS ONE POTENTIAL TIME THAT WOULD WARRANT HIGHER POPS...ESPECIALLY ACROSS THE WESTERN AND NORTHERN PARTS OF THE REGION. ANOTHER OPPORTUNITY MAY BE FRIDAY NIGHT ACROSS MAINLY NORTHERN AND EASTERN PARTS OF THE AREA. FINALLY...SATURDAY NIGHT MAY PROVE TO BE A THIRD OPPORTUNITY FOR ALL OF THE REGION...ESPECIALLY CENTRAL AND WESTERN PORTIONS. AT THIS TIME...CONFIDENCE IS NOT THERE TO OFFER A CATEGORICAL...75 PERCENT OR HIGHER...CHANCE OF PRECIPITATION FOR ANY ONE OF THE THREE SCENARIOS LISTED ABOVE. HOWEVER...WILL CONTINUE...OR ADD...A FORECAST OF LIKELY POPS TO THE FIRST AND SECOND SCENARIOS. FOR THE THIRD SCENARIO...WILL OFFER A FORECAST JUST SHY OF LIKELY POPS. TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO GRADUALLY COOL AS THE BAROCLINIC ZONE MAKES PROGRESS WESTWARD. THE COMBINATION OF MORE CLOUD COVER AND MORE PRECIPITATION...ALONG WITH LOWER HEIGHTS WILL CONTRIBUTE TO THIS. BY SATURDAY...THE SURFACE COLD FRONT MAY BE BISECTING THE REGION FROM NW-SE...THUS YIELDING NOTABLY COOLER TEMPERATURES AT LEAST FOR THE CENTRAL AND NORTHEAST PARTS OF THE AREA. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 130 PM EDT TUESDAY... THE WEEKEND THROUGH EARLY NEXT WEEK WILL BE CHARACTERIZED BY THE BATTLE BETWEEN LARGE UPPER RIDGE TO OUR WEST TRYING TO BUILD INTO SOUTHERN APPALACHIANS...WHILE TROUGH OFF NEW ENGLAND COAST DEEPENS WHILE CLOSING OFF AND CONTINUES TO APPEAR THAT IT WILL SET UP CLOSE ENOUGH TO COAST TO PUSH BACK DOOR FRONT THROUGH AND WELL SOUTH OF THE AREA THROUGH THE WEEKEND...BEFORE LIKELY WEAKENING AND ALLOWING MORE INFLUENCE OF THE RIDGE TO BE FELT BY TUES...ESPECIALLY ACROSS WESTERN PARTS OF THE AREA IF WEAK/SHALLOW BOUNDARY LAYER WEDGE IS IN PLACE EARLY IN THE DAY BEFORE MIXING OUT OVER THE EAST. WHILE SURFACE WEDGE FRONT MAY BE WELL TO THE SOUTH DURING MUCH OF THIS PERIOD...WITH STRONGEST SOUTHWARD PUSH ON SATURDAY...THE 850 BOUNDARY AND MOST LIKELY TRACK FOR UPPER S/WV ENERGY FROM THE NW IS LIKELY TO BE RIGHT OVER THE BLACKSBURG FORECAST AREA...AND THUS GOOD CHANCE FOR SHOWERS/THUNDERSTORMS THROUGH THIS ENTIRE PERIOD. TIMING MOST LIKELY WINDOWS REMAINS TRICKY...AS MANY OF THESE WAVES ARE STRONGLY INFLUENCE BY CONVECTIVE COMPLEXES THAT WILL DEVELOP WELL UPSTREAM. LIKE THE TRENDS OVERALL THAT 12Z GFS IS TAKING...NOT ONLY WITH RETURN TO SHARPER AMPLITUDE PATTERN...BUT IDEA OF TWO DISTINCT WAVES HEADING FOR THE WESTERN PART OF OUR FORECAST AREA...ONE SATURDAY AND ANOTHER ONE SUNDAY. EXACT TIMES MAY HELP DETERMINE IF THERE WILL BE ENOUGH INSTABILITY...WHICH WOULD LIKELY BE LIMITED TO THE FAR WEST NEAR EDGE OF WEDGE BOUNDARY...BUT PERHAPS THE BIGGER CONCERN IS RAINFALL THAT IS LIKELY TO IMPACT THE SAME AREAS AT LEAST A COUPLE OF DAYS IN A ROW. THERE COULD BE ANOTHER WAVE FOR MONDAY...BUT AS RIDGE ATTEMPTS TO BUILD IN AND TROUGH TO THE EAST AND ASSOCIATED WEDGE WEAKEN WHAT MAY TEND TO OCCUR IS MORE DIURNAL POP-UP CONVECTION ALONG AND NEAR THE WESTERN PERIPHERY OF THE WEDGE BOUNDARY IN OUR WESTERN FORECAST AREA AS THE ATMOS DESTABILIZES MORE. BY TUESDAY THE SUPPORT TO KEEP WEDGE IN PLACE SHOULD BE WEAKENING AS TROUGH LIFTS AND SFC HIGH SHIFTS MORE EAST OF THE AREA...AND OVERALL IT LOOKS A LITTLE DRIER...BUT NOT SURE ALL POPS CAN BE REMOVED. GIVEN PATTERN WE`VE BEEN IN...REALLY DON`T HAVE CONFIDENCE TO DRY IT OUT OR WARM IT UP TOO FAST...SO WILL LEAN TOWARD STRONGER INFLUENCE OF THE WEDGE THROUGH THIS PERIOD AND BETTER CHANCES FOR PRECIP...WHICH WILL HELP STRENGTHEN THE WEDGE TOO. UNDERCUT EVEN COOLER ECMWF A LITTLE BIT FOR HIGHS...WITH A BIT MORE WARMING FOR TUESDAY. BUT IN THE FAR SOUTHWEST THINGS MAY BE ABLE TO WARM UP VERY QUICKLY A DAY OR TWO EARLIER THAN THIS IF THE WEDGE CAN BREAK AND SOME OF THE INFLUENCE OF THE BIG UPPER RIDGE CAN BE REALIZED. THIS WILL EVENTUALLY RESULT IN A SIGNIFICANT WARM UP FOR OUR ENTIRE AREA...BUT AM THINKING IT WILL NOT COME UNTIL MIDDLE OF NEXT WEEK. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... AS OF 200 AM EDT WEDNESDAY... BKN LINE OF SHRA/TSRA WILL CROSS THE FORECAST AREA TODAY. SHRA/TSRA WILL PASS THROUGH THE MTNS THIS MORNING CROSSING BLF/LWB/BCB BETWEEN 12-15Z/8-11AM...THEN MOVE EAST OF THE MTNS AROUND MID-DAY WITH POTENTIAL FOR SHOWERS AND POSSIBLE THUNDERSTORM VCNTY OF ROA/LYH/DAN DURING THE EARLY/MID AFTERNOON. AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EAST ACROSS THE GREAT LAKES AND OHIO VALLEY TODAY...AND INTO NEW ENGLAND THURSDAY. THE TROF AXIS IS ASSOCIATED WITH A LINE OF SHOWERS AND THUNDERSTORMS WHICH WILL MOVE THROUGH THE MOUNTAINS THIS MORNING AND INTO THE PIEDMONT THIS AFTERNOON. STORMINESS SHOULD CLEAR THE FORECAST AREA BY 22Z/6PM THIS EVENING WITH ACTIVITY MOVING EAST. AREAS OF FOG WILL THEN RE-DEVELOP ACROSS THE AREA TONIGHT WITH AREAS OF MVFR AND POTENTIAL FOR IFR VSBYS AGAIN THURSDAY MORNING. EXTENDED AVIATION... WEATHER CONDITIONS WILL CONTINUE TO BE UNSETTLED AND HIGHLY VARIABLE FOR THE NEXT FEW DAYS AS A STATIONARY FRONT REMAINS STALLED OVER THE MID ATLANTIC. UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...SK NEAR TERM...JH/PM SHORT TERM...DS LONG TERM...SK AVIATION...PM
AREA FORECAST DISCUSSION
NWS PORTLAND OR
220 PM PDT WED AUG 20 2014 .SYNOPSIS...NORTHWEST FLOW WILL CONTINUE OVER THE REGION FOR MUCH OF THE WEEK. AN UPPER LEVEL LOW PRESSURE DROPPING SOUTHEAST ACROSS THE INLAND NORTHWEST ON FRIDAY...COULD RESULT IN A SOME LIGHT PRECIPITATION TO THE NORTHERN ZONES...AND A SLIM THREAT OF THUNDERSTORMS ACROSS THE SOUTH WASHINGTON AND NORTH OREGON CASCADES. NORTHWEST TO NORTH FLOW ALOFT CONTINUES OVER THE WEEKEND MAINTAINING ONSHORE LOW-LEVEL FLOW AND NEAR NORMAL OR SLIGHTLY BELOW NORMAL DAYTIME TEMPERATURES. HIGH PRESSURE STRENGTHENS JUST OFFSHORE EARLY NEXT WEEK...WHICH MAY RESULT IN SOME LIGHT OFFSHORE LOW-LEVEL FLOW. && .SHORT TERM...TONIGHT THROUGH SATURDAY...MORNING STRATUS LAYER HAS TRANSFORMED INTO A BROKEN STRATOCUMULUS FIELD WITH CIGS GENERALLY 035 TO 045. MODERATE TO STRONG ONSHORE LOW-LEVEL FLOW CONTINUES TONIGHT THROUGH THURSDAY...AND EXPECT SIMILAR DRIZZLE COVERAGE TONIGHT AND THURSDAY MORNING COMPARED TO TODAY. SW WA LOWLANDS... OREGON COAST...AND WEST SLOPES OF THE COAST RANGE SOME OF THE MORE FAVORED DRIZZLE AREAS. KTTD-KDLS GRADIENT UP TO 4.0 MB AS OF 20Z...WHICH NORMALLY RESULTS IN AT LEAST 25-30 MPH GUSTS NEAR HOOD RIVER. AUGSPURGER...AN ELEVATED BPA SITE ON THE WASHINGTON SIDE OF THE GORGE...GUSTING TO 35 MPH. EXPECT SIMILAR CONDITIONS THURSDAY. MAIN FORECAST CHANGES CENTER ON LATE THURSDAY NIGHT THROUGH FRIDAY PERIOD. LATEST NAM AND ECMWF CONTINUE TO INDICATE AREAS OF LIGHT QPF FURTHER WEST THAN PREVIOUS COUPLE OF RUNS. BOTH MODELS SHOW THE UPPER TROUGH DIGGING AS A REINFORCING SHORT-WAVE DROPS SOUTH INTO THE TROUGH BASE...AIDED BY A 80-100 KT 300 MB JET STREAK. NAM SHOWS FAIRLY ROBUST 700 MB OMEGA FOCUSED OVER SW WA AND EXTREME NW OREGON 12Z FRI. WOULD EXPECT A MUCH DEEPER MARINE LAYER WITH ENOUGH LIFT FOR AT LEAST AREAS OF DRIZZLE LATE THU NIGHT THROUGH FRI MORNING IN THE LOWLANDS AND POSSIBLY SPOTTY LIGHT SHOWERS OVER ELEVATED TERRAIN. ANY DRIZZLE OR LIGHT SHOWERS SHOULD BE CONFINED TO THE NORTHERN TWO-THIRDS OF THE FORECAST AREA. THERE IS STILL SOME VARIABILITY AMONG THE MODEL SOLUTIONS WITH REGARD TO THE ACTUAL LOW TRACK BUT MODELS GENERATE ENOUGH INSTABILITY OVER THE S WA AND FAR N OREGON CASCADES FRI AFTERNOON FOR A SLIM THREAT OF THUNDERSTORMS. ANY STORMS WHICH DO DEVELOP AND TRY TO MOVE WEST TO SOUTHWEST OFF THE HIGHER TERRAIN WILL RUN INTO A MORE STABLE AIR MASS OVERALL ON TOP OF THE ALREADY STABLE LOW LEVEL MARINE INFLUENCED LOW LEVELS. CYCLONIC JET FROM THE DEPARTING LOW CLOSE ENOUGH TO THE CASCADE CREST TO LEAVE SLIGHT CHANCE POPS THERE SAT...PRIMARILY IN THE MORNING. WEISHAAR .LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...A SHORTWAVE ON THE BACK SIDE OF THE TROUGH WILL PASS OVER OUR AREA SATURDAY NIGHT...SEEN AT 500 AND 850 MB. THIS WILL ONLY BRING A SLIGHT CHANCE OF RAIN IN THE NORTH OREGON AND SOUTHERN WASHINGTON CASCADES...AS MOISTURE IS VERY LIMITED FROM NORTHERLY CONTINENTAL FLOW AND NEGATIVE VORTICITY ADVECTION WILL PROMOTE DOWNWARD MOTION OVER THE WESTERN 2/3 OF OUR AREA. AS THE LONGWAVE TROUGH PROGRESSES EASTWARD...THE RIDGE CURRENTLY OVER A GOOD PORTION OF THE NORTH PACIFIC WILL MOVE ONSHORE OVER THE WEST COAST WHICH WILL BRING TEMPERATURES UP AND DRY CONDITIONS EARLY NEXT WEEK. -MCCOY && .AVIATION...GENERALLY VFR CONDITIONS THIS AFTERNOON WITH SCT CLOUDS AND SOME CIGS 3000 TO 4000 FT. CLEARING TREND WILL CONTINUE INTO THE OVERNIGHT HOURS INLAND WHILE ONSHORE FLOW BRINGS MVFR CIGS BACK TO COAST AFT 02Z. MARINE STRATUS WILL PUSH INLAND AGAIN TONIGHT WITH CIGS AROUND 2500 FT BUT LATEST GUIDANCE SHOWS BEST LIKELIHOOD ON THE NORTH SIDE OF THE RIVER. COULD SEE SOME SCATTERED CLOUDS FARTHER SOUTH IN THE VALLEY BUT GENERALLY VFR CONDITIONS SHOULD PREVAIL SOUTH OF PDX. KPDX AND APPROACHES...VFR WITH CLEARING SKIES THIS AFTERNOON. COULD SEE SOME MVFR CIGS AROUND 2500 FT THURSDAY MORNING AFTER 13Z BUT NOT AS WIDESPREAD AS THIS MORNING. BOWEN && .MARINE...BUOYS SHOWING 4 TO 6 FT SEAS AT 10 SECONDS BUT THERE`S ALSO ENERGY AT 8 SECONDS SO SEAS WILL BE A BIT STEEP THROUGH THIS EVENING. NW WINDS REMAIN RATHER LIGHT...LESS THAN 15 KT. VERY LITTLE CHANGE IN THE PATTERN THROUGH THE WEEKEND WITH CONTINUED NW WIND AND SWELL. PRESSURE GRADIENT TIGHTENS SOME FRIDAY AND SATURDAY AFTERNOONS AS HIGH PRESSURE OVER THE NE PACIFIC STRENGTHENS A BIT WITH THERMAL LOW OVER NORTHERN CALIFORNIA...INCREASING WINDS TO 15 TO 20 KT WITH SLIGHTLY HIGHER GUSTS. BOWEN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...NONE. && $$ INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/NWSPORTLAND 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 National Weather Service Spokane WA 1120 AM PDT WED AUG 20 2014 .SYNOPSIS... Cooler temperatures and the occasional threat of showers and thunderstorms will linger the rest of the week and into the weekend. However, the vast majority of this precipitation will be in the North Idaho Panhandle. && .DISCUSSION... Forecast update to increase precip chances across the northern mountains for this afternoon. Some residual elevated convection is continuing to march eastward along the Canadian border in the Northern Panhandle late this morning. This is expected to push across some thunderstorms near Bonners Ferry and Porthill. Once this cloud cover associated with the nocturnal convection clears the region, we will see a redevelopment of showers and thunderstorms over the higher terrain from west to east. This set up looks very similar to what happened yesterday. The HRRR model has been consistent with thunderstorms developing over the East Slopes of the Northern Cascades into the Okanogan Highlands around noon. These storms will generally push to the east at approximately 20 mph through the afternoon. A redevelopment of thunderstorms today will be more toward the mid and late afternoon hours for the Northeast Mountains and the Northern Panhandle. Looks like there will be a slight northwesterly component to the steering flow for these thunderstorms today, so the northern Upper Columbia Basin to the Spokane/Coeur d`Alene corridor will see a chance for isolated to scattered thunderstorms as well. Thunderstorms are expected to hold off for the Spokane/Coeur d`Alene corridor until the late afternoon and evening hours. The 12Z model runs continue to show upwards of 700-1000 J/KG of surface based CAPE across the northern mountains this afternoon. The 0-6 km bulk shear will be slightly stronger today at around 20 kts or so. This shear is still a bit weak for much in the may of concern for strong to severe thunderstorms; however, we did see a storm pulse up quickly to severe levels yesterday over the northern Upper Columbia Basin in a weakly sheared environment, so it will not be out of the realm of possibility today as well. Due to the weak shear though, thunderstorms will be of the pulse variety. Any stronger storms that due develop will likely collapse fairly quickly. I did add small hail, heavy rain, and frequent lightning to the forecast across the northern mountains today considering that these impacts were observed with the thunderstorm activity yesterday. /SVH && .AVIATION... 18Z TAFS: An are of isolated thunderstorm activity will track across the Northern Panhandle late this morning. A resurgence of thunderstorms is expected across the northern mountains today once we warm to our convective temperature. These thunderstorms are expected to push into the vicinity of KGEG, KSFF and KCOE by late this afternoon and early evening. Impacts from convection today will include: outflow winds up to 35 mph, small hail and brief downbursts of heavy rain. Showers and thunderstorms will wind down after 06Z this evening. /SVH && .PRELIMINARY POINT TEMPS/POPS... Spokane 80 56 79 52 75 52 / 20 40 10 10 20 30 Coeur d`Alene 79 55 77 50 74 50 / 10 50 10 10 30 40 Pullman 80 50 79 46 76 51 / 10 0 10 10 20 40 Lewiston 85 59 85 57 83 58 / 10 0 0 0 20 30 Colville 76 54 79 52 78 50 / 70 50 50 50 40 30 Sandpoint 77 52 73 51 72 50 / 60 60 50 50 50 30 Kellogg 75 53 73 51 71 49 / 20 40 20 20 40 50 Moses Lake 86 56 84 53 82 56 / 0 0 10 10 20 20 Wenatchee 84 60 83 59 80 59 / 0 0 10 10 20 20 Omak 86 59 84 55 80 55 / 40 20 20 40 30 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
908 PM CDT THU AUG 21 2014 .UPDATE... ISSUED AT 908 PM CDT THU AUG 21 2014 THE MAIN FOCUS FOR THE OVERNIGHT HOURS IS WITH CONVECTIVE TRENDS AND THE POTENTIAL FOR WIDESPREAD FOG. SO FAR THIS EVENING...THE MAIN CONVECTION HAS BEEN TIED TO A NARROW CORRIDOR ALONG AND AHEAD OF A SURFACE COLD FRONT/LOW THAT RUNS FROM NORTHWEST WISCONSIN THROUGH SOUTH CENTRAL MINNESOTA. 22.01Z RAP ANALYSIS SHOWS THAT SBCAPE IS ON THE WANE WITH THE TWO MAIN AREAS OF CONVECTION ALONG THE NORTHERN GRADIENT IN INSTABILITY...NW WI...AND THE OTHER MAIN CELLS ALONG THE HIGHEST INSTABILITY AXIS POKING INTO NW IOWA. THE MAIN CONVERGENCE WILL REMAIN WITH THIS SLOW MOVING FRONT THROUGH THE NIGHT THOUGH SURFACE/LOW LEVEL WINDS WILL BE DECREASING THROUGH THE NIGHT THUS WEAKENING THIS CONVERGENCE. WHILE SFC/ML INSTABILITY WILL BE DECREASING THROUGH THE NIGHT...0-3KM MUCAPE ACTUALLY GETS A BUMP UP PER THE 22.01Z RAP AS THE FRONT APPROACHES LATE. THERMAL PROFILES ARE FAIRLY WARM...SO IT WILL TAKE QUITE THE UPDRAFT TO GET ANY OF THE CONVECTION TO GO SEVERE WHICH DOES NOT LOOK LIKE IT WILL HAPPEN BASED ON THE WEAKENING CONVERGENCE. STILL MAY MANAGE TO SEE A FEW SHOWERS...JUST NOT EXPECTING ANYTHING THAT WOULD GET OUT OF HAND. WITH A HUMID AIR MASS IN PLACE WITH SURFACE DEW POINTS IN THE LOW 70S...FOG STILL LOOKS LIKE A POSSIBILITY OVERNIGHT. THE 21.21Z SREF IS LOCKING ONTO NORTHERN WISCONSIN WHERE IT APPEARS THAT A WEAK WARM FRONT IS LOCATED AND SOME LOCATIONS HAVE ALREADY STARTED TO DROP BELOW 1SM. WITH WINDS LIGHTENING UP AS THE LOW/FRONT APPROACHES...SOME MORE SITES COULD DEVELOP FOG OVERNIGHT IF THE SKIES CAN CLEAR OUT. HIGH LEVEL CLOUD COVER IS BLOWING OFF OF THE CONVECTION IN SOUTHWEST MINNESOTA AND COULD INITIALLY SLOW THINGS DOWN...BUT EXPECT THAT SKIES WILL CONTINUE TO CLEAR AND LEAD TO THIS FOG DEVELOPMENT. CONFIDENCE IS NOT HIGH ENOUGH IN THE WHEN/WHERE TO ISSUE A DENSE FOG ADVISORY...BUT SOME PORTION OF THE AREA MAY NEED ONE LATER. && .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT) ISSUED AT 340 PM CDT THU AUG 21 2014 WATER VAPOR IMAGERY SHOWING THE STRONG MID-LEVEL WAVE THAT GAVE THE AREA MAINLY MORNING SHOWERS AND THUNDERSTORMS NOW OVER EASTERN WI. SUBSIDENCE IN THE WAKE OF THIS WAVE PROVIDED SOME PARTIAL SUNSHINE TO THE ARX FORECAST AREA WITH TEMPERATURES THIS AFTERNOON IN THE MID 70S TO THE LOWER 80S. ALSO...DEW POINTS WERE CREEPING UPWARD INTO THE MIDDLE 60S TO THE LOWER 70S FOR A BIT MORE MUGGY FEEL TO THE ATMOSPHERE. MODEL CONSENSUS SHOWS WARM FRONTAL BOUNDARY REMAINING JUST TO OUR SOUTH OVERNIGHT WITH MODELS INDICATING SOME 850MB MOISTURE TRANSPORT INTO/OVER IT. THIS IS IN ADVANCE OF A WEAKER MID-LEVEL WA DETERMINISTIC MODELS LOOK BIT OVERDONE WITH QPF BASED ON THIS WEAKER SIGNAL...SO WENT WITH SMALLER-END SHOWER/THUNDER CHANCES. WITH RECENT RAINFALL AND RELATIVELY WEAK WINDS OVERNIGHT...ANY BREAKS IN THE CLOUD COULD ALSO LEAD TO SOME FOG DEVELOPMENT. FRIDAY IS LOOKING MAINLY DRY ACROSS THE AREA WITH MID-LEVEL RIDGE AMPLIFYING OVERHEAD. HOWEVER...THE BOUNDARY WILL REMAIN JUST TO OUR SOUTH BUILDING INSTABILITY THROUGH THE AFTERNOON. NO REAL TRIGGER MECHANISM TO FOCUS CONVECTION OTHER THAN WEAK CONVERGENCE ALONG THE BOUNDARY. AS SUCH...WILL GO WITH A 20-30 PERCENT CHANCE OF SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST IA/SOUTHWEST WI. OTHERWISE...PLAN ON HIGHS IN THE 80S WITH HEAT INDICES CREEPING INTO THE 95-100 DEGREE RANGE ACROSS FAR NORTHEAST IA/FAR SOUTHWEST WI. FOR FRIDAY NIGHT...LOOKING FOR THAT BOUNDARY TO OUR SOUTH LIFT NORTH AS A WARM FRONT. THIS IS IN RESPONSE TO SURFACE CYCLOGENESIS OVER THE CENTRAL PLAINS. MODELS IN GOOD AGREEMENT IN KEEPING BEST 850MB MOISTURE TRANSPORT FOCUSED MORE ACROSS WESTERN IA/MN. AS SUCH...KEPT HIGHER POPS FOCUSED MORE ACROSS NORTHEAST IA/SOUTHEAST MN...TAPERING EASTWARD OF THE MISSISSIPPI. PRECIPITABLE WATER VALUES WILL BE QUITE HIGH IN THE 1.5-2 INCH RANGE...SO ANY STORMS WILL BE CAPABLE OF SOME HEAVIER RAINFALL. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 340 PM CDT THU AUG 21 2014 LOOK FOR THE WARM FRONT TO CONTINUE TO PUSH NORTHWARD ACROSS THE AREA SATURDAY THROUGH SATURDAY NIGHT FOR ADDITIONAL SHOWER AND THUNDERSTORM CHANCES. WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR POCKETS OF HEAVIER RAINFALL GIVEN HIGHER-END PRECIPITABLE WATER VALUES. SATURDAY AFTERNOON INTO SATURDAY EVENING MAY ALSO HAVE TO BE WATCHED FOR SEVERE THUNDERSTORM POTENTIAL AS NAM INDICATING 0-3KM MUCAPE IN THE 2000-4500J/KG RANGE WITH BULK SHEAR IN THE 20-25KT RANGE. LOOKS LIKE THE HIGHEST THREAT AREA WOULD BE ALONG AND WEST OF THE MISSISSIPPI RIVER. SUNDAY LOOKING HOT/MUGGY/CAPPED AS THE AREA BECOMES ENTRENCHED IN THE WARM SECTOR OF SURFACE LOW LIFTING NORTH ACROSS THE DAKOTAS INTO CANADA. NAM DRAWING IN 27-31C 925MB AIR INTO AREAS ALONG/WEST OF THE MISSISSIPPI RIVER IN THIS WARM SECTOR WHICH WOULD DICTATE TEMPERATURES NEARING 100. TOOK A MODEL CONSENSUS FOR NOW...YIELDING HIGHS IN THE 90S. WITH DEWPOINTS IN THE 70S...RESULTING HEAT INDICES WILL BE IN THE 100-105 DEGREE RANGE FOR AREAS ALONG AND SOUTH OF I- 90. WILL KEEP AN EYE ON THIS OVER THE NEXT DAY OR TWO FOR A POSSIBLE HEAT HEADLINE. SHOWER/THUNDERSTORM CHANCES RETURN SUNDAY NIGHT INTO MONDAY AS A COLD FRONT PUSHES INTO THE AREA. THIS FRONTAL BOUNDARY LOOKS LIKE IT WILL LINGER ACROSS AREA THROUGH AT LEAST WEDNESDAY FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 643 PM CDT THU AUG 21 2014 RECENT ANALYSIS SHOWS CONVECTIVE POTENTIAL AT KRST/KLSE CONTINUES TO DIMINISH...WITH THE MAIN FOCUS NOW ON FOG DEVELOPMENT TONIGHT. MOIST AIRMASS...LIGHT WINDS...AND MOSTLY CLEAR SKIES OVERNIGHT SHOULD SET THE STAGE FOR A PERIOD OF DENSE FOG AT BOTH KRST/KLSE. ENVIRONMENT LOOKS MORE FAVORABLE AT KLSE FOR A PROLONGED PERIOD OF LIFR VISIBILITY AND CEILINGS. FOG SHOULD BURN OFF BY MID MORNING...THEN GIVE WAY TO MOSTLY SUNNY SKIES AND SOUTH WINDS. && .HYDROLOGY...TODAY INTO TONIGHT ISSUED AT 340 PM CDT THU AUG 21 2014 A WARM FRONT WILL LIFT NORTHWARD THROUGH THE AREA FRIDAY NIGHT THROUGH SATURDAY NIGHT AND SERVE AS A TRIGGER FOR SHOWER/THUNDERSTORM DEVELOPMENT. PRECIPITABLE WATER VALUES WILL BE IN THE 1.5 TO 2 INCH RANGE. AS SUCH...ANY STORM WILL BE CAPABLE OF HEAVY RAINFALL. NOT THINKING ANY FLOOD HEADLINES WILL BE NEEDED AT THIS TIME BUT CERTAINLY WARRANTS A WATCHFUL EYE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...DAS LONG TERM....DAS AVIATION.....ZT HYDROLOGY....DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1151 PM CDT TUE AUG 19 2014 .SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT) ISSUED AT 252 PM CDT TUE AUG 19 2014 WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWING A MID- LEVEL LOW OVER WESTERN UPPER MICHIGAN. COLD POOL ALOFT ASSOCIATED WITH THE LOW PRODUCING WIDESPREAD CUMULUS/STRATOCUMULUS FIELD ACROSS THE FORECAST AREA WITH RADAR EVEN SHOWING A FEW SHOWERS POPPING UP ACROSS NORTHERN MN INTO NORTHERN WI. OTHERWISE...TEMPERATURE ACROSS THE ARX FORECAST AREA WERE IN THE 70-80 DEGREE RANGE. FOR TONIGHT...COULD SEE A FEW SHOWERS NORTHEAST OF I-94 THIS EVENING BUT THEN EXPECTING CLOUDS TO DIMINISH LATE IN THE EVENING AND THROUGH THE OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES OVERHEAD. THIS WILL SET UP FAVORABLE FOG POTENTIAL OVERNIGHT/EARLY WEDNESDAY MORNING...ESPECIALLY FAVORED RIVER VALLEY LOCATIONS. THINKING AREAS SOUTHWEST OF I-94 WILL BE MOST IMPACTED WHERE CONFIDENCE IS HIGHER FOR CLEARING SKY CONDITIONS EXISTS. HELD OFF ON DENSE FOG ADVISORY FOR NOW BASED ON INPUT FROM SURROUNDING OFFICES...BUT EVENING FORECASTER WILL HAVE TO MONITOR CLOSELY FOR POSSIBLE FOG HEADLINE. LOOK FOR LOWS TONIGHT IN THE MIDDLE 50S TO THE LOWER 60S. AFTER AREAS OF MORNING FOG...PLAN ON THE RIDGE OF HIGH PRESSURE TO KEEP THE FORECAST AREA DRY THROUGH WEDNESDAY. AN APPROACHING WARM FRONT FROM THE CENTRAL PLAINS/MID-MISSISSIPPI RIVER VALLEY WILL LIKELY SPARK A FEW SHOWERS AND THUNDERSTORMS...BUT PRETTY CONFIDENT THESE WILL REMAIN SOUTH OF THE AREA. OTHERWISE...EXPECTING HIGH TEMPERATURES TO TOP OFF IN THE MID 70S TO THE LOWER 80S. LOOK FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY BY LATE WEDNESDAY NIGHT AS THE WARM FRONT CONTINUES TO APPROACH THE REGION. ALL MODELS SHOW 850MB MOISTURE TRANSPORT INCREASING INTO/OVER THE FRONT...WITH BEST AXIS OF MOISTURE PLUME REMAINING JUST WEST OF THE FORECAST AREA. IN FACT...THE GFS/NAM SHOWING PRECIPITABLE WATER VALUES SURGING INTO THE 1.5-2 INCH RANGE. THIS COULD LEAD TO SOME LOCALIZED HEAVIER RAINFALL AS WARM CLOUD LAYER DEPTH INCREASE TO AROUND 4KM BY MORNING. MAY NEED TO MONITOR THE POTENTIAL FOR A FEW SEVERE THUNDERSTORMS WITH LARGE HAIL INITIALLY WITH THE INCOMING CONVECTION AS NAM INDICATING 1-6KM MUCAPE IN THE 2500-3500J/KG RANGE COUPLED WITH 25-35KT BULK SHEAR. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 252 PM CDT TUE AUG 19 2014 MODELS SHOWING THE WARM FRONT PUSHING NORTHEAST THROUGH THE AREA ON THURSDAY FOR THE CONTINUED LIKELIHOOD OF SHOWERS AND THUNDERSTORMS. MODELS ALSO SHOWING 850MB MOISTURE TRANSPORT WANING THROUGH THE MORNING HOURS AND EVENTUAL CAPPING ALONG AND WEST OF THE MISSISSIPPI DURING THE AFTERNOON HOURS. AS SUCH...DIVIDED POPS INTO MORNING/AFTERNOON TIME PERIODS. STILL LOOKING AT THE POTENTIAL FOR SOME LOCALIZED HEAVY RAINFALL THROUGH THE MORNING HOURS WITH PRECIPITABLE WATER VALUES LINGERING IN THE 1.5 TO 2 INCH RANGE. OTHERWISE...LOOK FOR SUBSTANTIALLY MORE HUMID CONDITIONS AS DEW POINTS CREEP UP INTO THE LOWER 70S. THESE DEW POINTS COMBINED WITH DAYTIME HIGHS WELL INTO THE 80S FOR MOST OF THE AREA ARE EXPECTED TO PRODUCE HEAT INDICES IN THE 90 TO 100 DEGREE...HIGHEST ALONG AND WEST/SOUTH OF THE MISSISSIPPI/WISCONSIN RIVERS. FOR THURSDAY NIGHT THROUGH THE REST OF THE PERIOD...FORECAST CONFIDENCE WANES FAIRLY RAPIDLY. MODEL CONSENSUS SHOWS A MID-LEVEL RIDGE TRYING TO ESTABLISH ITSELF OVER THE CENTRAL CONUS. HOWEVER...MESSY FLOW WITH MONSOONAL TAP WILL BE IN PLACE ACROSS THE INTERMOUNTAIN/PLAINS REGION. TIMING OF THESE WAVES PRETTY UNCERTAIN AT THIS TIME. AS SUCH...WILL KEEP LOW-MEDIUM RANGE SHOWER/THUNDERSTORM CHANCES IN THROUGH THE PERIOD. TEMPERATURES THROUGH THE PERIOD LOOK TO STAY AT OR A FEW DEGREES ABOVE NORMAL THROUGH THE WEEKEND...WITH PERHAPS SOME COOLING EARLY NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1151 PM CDT TUE AUG 19 2014 CONFIDENCE REMAINS FAIRLY HIGH THAT VALLEY FOG WILL DEVELOP OVERNIGHT WITH THE MAIN CONCERN JUST BEING WITH SOME SCATTERED MID LEVEL CLOUDS THAT HAVE BEEN DROPPING SOUTHEAST FROM MINNESOTA/NORTHWEST WISCONSIN. OTHERWISE...DEW POINT SPREADS ARE LOW...WINDS ARE CALM AT THE SURFACE AND LIGHT ON UP THROUGH THE LOWEST 3KFT. THE MAIN QUESTION IS JUST WITH HOW FAST THE FOG WILL FORM AND THEN DISSIPATE OVERNIGHT. ONSET STILL APPEARS TO BE AROUND 9Z WITH DISSIPATION COMING AROUND 14-15Z BASED ON CLIMATOLOGY. WITH THE RIDGE OVERHEAD...WINDS WILL REMAIN CALM WITH SKIES CLEAR FOR MUCH OF THE DAY BEFORE SHOWERS AND THUNDERSTORMS DEVELOP WEDNESDAY EVENING. THIS CONVECTION LOOKS LIKE IT WILL DEVELOP ALONG A NORTHWEST TO SOUTHEAST BAND AND COULD BE HEAVY AT TIMES...BRINGING VISIBILITY CONDITIONS TO IFR/MVFR. && .HYDROLOGY...WEDNESDAY NIGHT INTO THURSDAY ISSUED AT 252 PM CDT TUE AUG 19 2014 THERE IS THE LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS WITH THE POTENTIAL FOR HEAVY RAINFALL WEDNESDAY NIGHT INTO THURSDAY MORNING. EXPECTING FAIRLY WIDESPREAD 1/4 TO 3/4 INCH RAINFALL WITH LOCALIZED GREATER THAN 1 INCH AMOUNTS. THIS RAINFALL COMBINED WITH RECENT POCKETS OF HEAVY RAINS ACROSS PORTIONS OF THE FORECAST AREA COULD LEAD TO SOME LOCALIZED FLOODING CONCERNS. WILL KEEP A CLOSE EYE ON LOCALIZED FLOODING CONCERN AND THE POTENTIAL FOR A FLASH FLOOD WATCH HEADLINE WEDNESDAY NIGHT INTO THURSDAY MORNING ONCE CONFIDENCE INCREASES ON EXACTLY WHERE THE HEAVIER RAINFALL WILL OCCUR. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...HALBACH HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
330 PM MDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 330 PM MDT WED AUG 20 2014 CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND FEW THUNDER SHOWERS DEVELOPING OVER THE MOUNTAINS AND THE CHEYENNE RIDGE THIS AFTERNOON...AND SLOWLY MOVING EASTWARD. ACTIVITY HAS BEEN WEAK WITH ONLY A FEW ISOLATED LIGHTNING STRIKES. EXPECT THIS ACTIVITY TO CONTINUE THROUGH INTO LATE THIS AFTERNOON AND EARLY THIS EVENING WHILE DEVELOPING FURTHER EAST INTO THE HIGH PLAINS OF SOUTHEAST WYOMING. EXPECT ANY THUNDERSTORMS TO QUICKLY DIMINISH AROUND SUNSET. THUNDERSTORM COVERAGE WILL LIKELY BE LOWER ON THURSDAY ACROSS MOST OF THE FORECAST AREA AS WARMER AIR ALOFT MOVES INTO THE AREA AND 500MB HEIGHTS INCREASE THROUGH THE DAY. A COLD FRONT BOUNDARY WILL BECOME MORE NOTICEABLE FURTHER NORTH ACROSS MONTANA AND NORTHERN WYOMING AS IT SLOWLY DRIFTS SOUTHWARD THROUGH THE DAY. THEREFORE...EXPECT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS TO BE ACROSS THE MOUNTAINS AND WELL NORTH OF I80. CAN NOT RULE OUT A THUNDER SHOWER OR TWO ALONG THE I80 CORRIDOR DURING THE EVENING HOURS. TEMPERATURES WILL REMAIN NEAR NORMAL AND GENERALLY IN THE UPPER 70S WEST OF THE LARAMIE RANGE AND LOW 80S TO LOW 90S ACROSS THE EASTERN PLAINS. THIS PERSISTENT WEATHER PATTERN WILL BEGIN TO CHANGE ON FRIDAY AND ESPECIALLY THIS WEEKEND. MODELS INDICATE A PRETTY STRONG COLD FRONT FOR THIS TIME OF THE YEAR PUSHING SOUTHWARD INTO SOUTHEAST WYOMING. THIS FRONT WILL STALL SOMETIME ON FRIDAY AND BE THE MAIN FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND TSTORMS AS AN UPPER LEVEL TROUGH FROM WESTERN CANADA MOVE SOUTH AND EVENTUALLY EASTWARD INTO IDAHO. LOWERED MAX AND MIN TEMPERATURES FRIDAY AND FRIDAY NIGHT AND INCREASED POP BETWEEN 25 TO 45 PERCENT ACROSS THE HIGH PLAINS...AND NEAR 70 PERCENT OVER THE MOUNTAINS. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 330 PM MDT WED AUG 20 2014 BOTH THE GFS AND ECMWF BRING A SHORTWAVE THROUGH THE AREA IN SOUTHWEST WIND FLOW FRIDAY NIGHT INTO SATURDAY. ECMWF ROUGHLY 12 HOURS SLOWER THAN THE GFS...BUT BOTH ARE IN CLOSE AGREEMENT WITH MOVEMENT OF FIRST DISTURBANCE...THEN MOVING THE MAIN TROUGH THROUGH ON SATURDAY/SATURDAY NIGHT. JUST ABOUT EVERYONE SHOULD SEE SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY WITH BEST CHANCES FOR THE PANHANDLE SATURDAY NIGHT. MAIN SHORTWAVE THROUGH THE AREA BY SUNDAY...WITH MAINLY ISOLATED SHOWERS OVER THE MOUNTAINS. NEXT COLD FRONT LOOKS TO MOVE INTO THE AREA MONDAY AFTERNOON INTO TUESDAY. ECMWF A LITTLE COLDER THAN GFS IN 700MB TEMPERATURES...BUT NOT AS BAD AS A FEW DAYS AGO. PROBABLY NEED TO GO COLDER WITH THIS SETUP. DISCREPANCY MUCH GREATER ON TUESDAY WITH THE ECMWF FORECASTING 700MB TEMPERATURES OF +4 TO +6C AND GFS SHOWING +10 TO +12C. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 330 PM MDT WED AUG 20 2014 FOLLOWED LATEST HRRR GUIDANCE FOR TIMING ON SHOWERS AND THUNDERSTORMS FOR SOUTHEAST WYOMING AND NEBRASKA PANHANDLE AIRPORTS THIS AFTERNOON. HRRR HAS BEEN DOING WELL ON THE EARLY MORNING CONVECTION...SO SEE NO REASON TO DEVIATE. && .FIRE WEATHER... ISSUED AT 156 PM MDT WED AUG 20 2014 MINIMAL FIRE WEATHER CONCERNS INTO EARLY NEXT WEEK. SUBTROPICAL MOISTURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND WITH SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY ACROSS SOUTHEAST WYOMING AND WESTERN NEBRASKA. THERE IS A GOOD CHANCE OF WETTING RAINS BY FRIDAY AND THIS WEEKEND AS THUNDERSTORM COVERAGE WILL BE HIGHER. TEMPERATURES WILL TREND COOLER BY LATE THIS WEEK AND INTO THIS WEEKEND AS A STRONG COLD FRONT FOR THIS TIME OF THE YEAR MOVES INTO THE REGION LATE ON SATURDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...TJT LONG TERM...CLAYCOMB AVIATION...CLAYCOMB FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1034 AM MDT WED AUG 20 2014 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 350 AM MDT WED AUG 20 2014 INITIAL SHORTWAVE TROUGH ALOFT MOVES ACROSS OUR COUNTIES EARLY IN THE DAY...WITH A WEAKER...SECONDARY SHORTWAVE TROUGH APPROACHING OUR WESTERN COUNTIES IN THE LATE AFTERNOON. SOME LOW LEVEL DRYING NOTED IN THE WAKE OF THE MORNING SHORTWAVE TROUGH... THOUGH IT APPEARS THERE WILL BE ENOUGH LOW AND MID LEVEL MOISTURE THIS AFTERNOON TO SPARK ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS...MOST NUMEROUS WEST OF INTERSTATE 25. TONIGHT...SHOWERS AND THUNDERSTORMS ENDING IN THE EVENING WITH THE LOSS OF DAYTIME HEATING AND ABSENCE OF ANY OTHER LIFTING MECHANISMS. THURSDAY...SOUTHWEST FLOW ALOFT CONTINUES AND WITH ADEQUATE LOW AND MID LEVEL MOISTURE IN PLACE...WILL SEE ISOLATED LATE DAY THUNDERSTORMS ALONG AND WEST OF A LUSK TO CHEYENNE LINE. THURSDAY NIGHT...WEAK COLD FRONT ENTERS FROM THE NORTH...THOUGH WITH MINIMAL LOW AND MID LEVEL MOISTURE...RAIN CHANCES WILL BE SLIM. LATE IN THE NIGHT...WILL GO WITH ISOLATED SHOWERS AFTER MIDNIGHT EAST OF A DOUGLAS TO SIDNEY LINE IN LOW LEVEL CONVERGENCE BOUNDARY. FRIDAY...INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THURSDAY AS A NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT PROPAGATES ACROSS OUR WESTERN NEBRASKA COUNTIES...WITH ENHANCED SOUTHEAST LOW LEVEL WINDS ADVECTING MOISTURE IN...AND PROVIDING MECHANICAL LIFT TO HELP GENERATE THUNDERSTORMS. .LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY) ISSUED AT 350 AM MDT WED AUG 20 2014 00Z MEDIUM RANGE GUIDANCE ARE CONSISTENT IN SWINGING AN UPPER TROUGH THRU THE NRN ROCKIES OVR THE WEEKEND. THIS IS AN EARLY INDICATION OF THE SEASONAL PATTERN CHANGE THAT WILL CONTINUE OVR THE NEXT FEW MONTHS. SATURDAY STILL LOOKS RELATIVELY WARM IN THE PREFRONTAL AIR MASS...ESPECIALLY OVR THE ERN PLAINS. MODELS PROG 1000-1500 J/KG AHEAD OF THE FRONT SATURDAY AFTERNOON. THE FAVORABLE THERMODYNAMIC PROFILE COMBINED WITH THE PROXIMITY OF RRQ OF A JET STREAK SUGGESTS AT LEAST THE POSSIBILITY OF A FEW STRONGER STORMS OVR THE PLAINS SATURDAY AFTERNOON. OF COURSE...MUCH OF THIS SCENARIO IS DEPENDENT UPON THE CURRENT TIMING OF LATE SATURDAY AND SATURDAY EVENING FROPA. CONVECTION WILL TURN MORE SHOWERY IN THE WAKE OF THE FRONT SATURDAY NIGHT. SUNDAY WILL BE NOTICEABLY COOLER POST-FRONTAL WITH HIGHS ONLY REACHING 70S AT MOST LOCATIONS. LEFT MOSTLY SHOWER CHANCES ALONG WITH ISOLD THUNDER MENTION GOING FOR SUNDAY. THIS WILL DEPEND UPON JUST HOW MUCH CLEARING OCCURS. TEMPERATURES RETURN TO MORE SEASONAL VALUES FOR MON-TUE TIMEFRAME. HARD TO REMOVE MENTION OF DAILY AFTERNOON AND EVENING CONVECTION EARLY NEXT WEEK AS PERSISTENT SOUTHWEST FLOW EJECTS IMPOSSIBLE TO TIME EMBEDDED SHORTWAVES. PRECIP DEFINITELY WONT BE AN ALL DAY OCCURRENCE...BUT CANT RULE OUT ITS POSSIBILITY MAINLY DURING THE AFTERNOON AND EVENING HOURS. THE PATTERN LOOKS TO TREND DRIER FOR THE LATTER HALF OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 1033 AM MDT WED AUG 20 2014 FOLLOWED LATEST HRRR GUIDANCE FOR TIMING ON SHOWERS AND THUNDERSTORMS FOR SOUTHEAST WYOMING AND NEBRASKA PANHANDLE AIRPORTS THIS AFTERNOON. HRRR HAS BEEN DOING WELL ON THE EARLY MORNING CONVECTION...SO SEE NO REASON TO DEVIATE. && .FIRE WEATHER... ISSUED AT 350 AM MDT WED AUG 20 2014 HUMIDITIES AND WINDS WILL REMAIN BELOW CRITICAL THRESHOLDS THE NEXT FEW DAYS...THUS MINIMAL FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RUBIN LONG TERM...HAHN AVIATION...CLAYCOMB FIRE WEATHER...RUBIN
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1216 AM MDT WED AUG 20 2014 .UPDATE... ISSUED AT 958 PM MDT TUE AUG 19 2014 STRONG TO SEVERE THUNDERSTORM CHANCES HAVE ENDED FOR THE REST OF TONIGHT. WILL MAINLY SEE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THE REST OF TONIGHT. && .SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT) ISSUED AT 250 PM MDT TUE AUG 19 2014 THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS WHERE THE CONVECTION WILL BREAK OUT THIS AFTERNOON AND HOW MUCH CONVECTION WILL BREAK OUT AHEAD OF THE JET STREAK MOVING ACROSS THE ROCKIES TONIGHT. LATEST VISIBLE IMAGERY WAS SHOWING SOME ACCAS DEVELOPING ACROSS NORTHEAST COLORADO NEAR THE SURFACE TROF. THIS AREA MAY END UP BEING THE FIRST AREA TO FIRE UP THIS AFTERNOON. HOWEVER...IT MAY TRY TO IGNITE JUST EAST OF THE LARAMIE AND FRONT RANGES AS WELL WHERE WE HAVE HAD QUITE A BIT OF SUNSHINE. IN FACT...WE ARE STARTING TO SEE A LITTLE BIT OF ACCAS OVERHEAD AND CONVECTION DEVELOPING ALONG THE FRONT RANGE. MODELS ARE PROJECTING MIXED LAYER CAPES TO APPROACH 1500 J/KG THIS AFTERNOON WITH VERY LIMITED CAP. 0-6KM SHEAR VALUES (~30KTS) MAY ALSO BE FAVORABLE FOR A FEW STRONG TO SEVERE STORMS. AT THIS POINT...IT LOOKS THE HRRR IS STARTING TO BREAK OUT CONVECTION JUST EAST OF CHEYENNE AFTER 21Z WITH THE BULK OF THIS CONVECTION PUSHING GENERALLY EAST AT AROUND 20KTS. A FEW OF THESE STORMS MAY HAVE THE POTENTIAL TO PRODUCING STRONG WINDS AND HAIL IN THE PANHANDLE THIS AFTERNOON. LATEST SURFACE ANALYSIS WAS ALSO SHOWING SOME WINDS BACKING TO THE SOUTHEAST IN THE PANHANDLE. WE WILL ALSO NEED TO WATCH THAT AS THE AFTERNOON WEARS ON...ESPECIALLY IF THE STORMS GET GOING IN THAT REGION. ANOTHER CONCERN IS THE NAM IS SHOWING A 500MB JET STREAK MOVING OUT OF NORTHEAST COLORADO EARLY THIS EVENING WHICH MAY HELP ENHANCE THE SHEAR ACROSS THE PANHANDLE. IF CONVECTION IS ON GOING IN THAT REGION AS THIS JET STREAK MOVES ACROSS WE MAY HAVE MORE OF A SEVERE POTENTIAL. THEREFORE...IT WILL BE A MATTER OF TIMING ON HOW THINGS COME TOGETHER LATE THIS AFTERNOON AND EVENING. TONIGHT THE MODELS ARE SHOWING A FAIRLY STRONG UPPER LEVEL JET MOVING THROUGH NORTHERN COLORADO AND LIFTING NORTHEAST INTO NORTHEAST WYOMING BY DAYBREAK WHICH WILL HELP ENHANCE UPPER LEVEL DIFFLUENCE. THE MODELS ARE EVEN IN FAIRLY GOOD AGREEMENT IN SHOWING A MID LEVEL CIRCULATION WITH THIS JET STREAK. AS A RESULT... WE WOULD NOT SURPRISED TO SEE A COMPLEX OF SHOWERS AND THUNDERSTORMS DEVELOP ACROSS THE WESTERN HALF OF THE FORECAST AREA OVERNIGHT ALONG WITH THE POTENTIAL FOR HEAVY RAINFALL DUE TO PRECIPITABLE WATER VALUES AROUND 1 INCH. NOT EXPECTING MUCH IN THE WAY OF FLOODING SINCE THIS COMPLEX SHOULD BE FAIRLY PROGRESSIVE. WE DID BUMP UP POPS ACROSS THE NORTHERN HALF OF THE AREA TONIGHT TO REFLECT THIS POTENTIAL. WEDNESDAY-THURSDAY NIGHT: THE MID LEVEL CIRCULATION IS PROGGED TO CONTINUE LIFTING NORTHEAST WHICH WILL TAKE THE BULK OF THE CONVECTION NORTHEAST OF THE FORECAST AREA BY MID MORNING. THIS WILL LEAVE A FAIRLY BROAD AREA OF SUBSIDENCE IN THE MORNING IN THE WAKE OF THE CONVECTION...BUT WE MAY MORE CONVECTION DEVELOP IN THE AFTERNOON ACROSS THE MOUNTAINS AS UPSLOPE FLOW COMMENCES WITH LEFTOVER RESIDUAL MOISTURE. OTHERWISE...THE REMAINDER OF THE AREA EAST OF THE LARAMIE RANGE SHOULD REMAIN FAIRLY DRY WITH HIGHS GENERALLY IN THE 80S. THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS IS PROGGED TO TAKE PLACE ON THURSDAY AFTERNOON AS ANOTHER UPPER LEVEL WAVE LIFTS NORTHEAST OUT OF COLORADO AND PUSHES THROUGH AREAS EAST OF THE LARAMIE RANGE THURSDAY AFTERNOON INTO THURSDAY NIGHT. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 250 PM MDT TUE AUG 19 2014 AN UPPER LOW AND ASSOCIATED TROUGH OVER THE PACIFIC NW FRIDAY WILL MOVE SLOWLY EAST TOWARDS THE AREA FRIDAY THROUGH SATURDAY... SWINGING BY THE AREA ON SUNDAY. THIS WILL COMBINE WITH AT LEAST RESIDUAL MONSOONAL MOISTURE TO KEEP CHANCES FOR SHOWERS AND TSTMS GOING OVER MOST AREAS THROUGH SATURDAY NIGHT. WILL CONTINUE TO LEAN TOWARDS THE EC SOLUTION AS IT HAS BEEN FAIRLY CONSISTENT WITH THIS FEATURE. WARM TEMPS WILL CONTINUE THROUGH SATURDAY THEN A DECENT COOL FRONT WILL PASS ACROSS SAT NIGHT LEAVING A DRIER AND MILD DAY FOR THE CWA SUNDAY. CONTINUED MILD ON MONDAY WITH THE CWA ON THE SOUTHERN PORTION OF BROAD CYCLONIC UPPER FLOW THAT WILL BE OVER THE NORTHERN PART OF THE COUNTRY. A SECOND UPPER SHORTWAVE SHOULD PASS BY TUESDAY BRINGING A REINFORCING SHOT OF COOLER AIR AND A CHANCE FOR SOME PRECIPITATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1215 AM MDT WED AUG 20 2014 SHOWERS WILL INCREASE FROM WEST TO EAST ACROSS THE AREA TONIGHT. VFR CONDITIONS ARE EXPECTED FOR MOST TERMINALS WITH CIGS BETWEEN 5K AND 10K FEET AGL. BRIEF MVFR CIGS OR VSBYS COULD OCCUR WITH ANY HEAVIER PRECIPITATION AFTER 06Z. ISOLATED SHOWERS OR WEAK TSTMS COULD BE IN THE VICINITY OF MOST TERMINALS THROUGH MOST OF THE TAF PERIOD. WINDS WILL GENERALLY BE BELOW 15 KTS...EXCEPT GUSTY AND VARIABLE NEAR ANY SHOWERS. && .FIRE WEATHER... ISSUED AT 1056 AM MDT TUE AUG 19 2014 FIRE WEATHER CONCERNS TO REMAIN MINIMAL FOR THE REST OF THE WEEK WITH NON-CRITICAL WEATHER CONDITIONS EXPECTED. SOME WETTING RAINS SHOULD OCCUR OVER AT LEAST PARTS OF THE AREA OVER THE NEXT COUPLE DAYS AS A SURGE OF MONSOONAL MOISTURE PASSES OVER THE REGION AND INCREASES PRECIPITATION. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...SML SHORT TERM...REC LONG TERM...RE AVIATION...HAMMER FIRE WEATHER...RE
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
157 AM MST FRI AUG 22 2014 .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO MOVE THROUGH THE AREA TODAY...HOWEVER ONLY A FEW ISOLATED SHOWERS ARE EXPECTED ACROSS THE REGION. DRIER CONDITIONS ARE EXPECTED ACROSS THE AREA THROUGH THE WEEKEND ALONG WITH SLIGHTLY COOLER THAN NORMAL TEMPERATURES. A RETURN TO A MORE TYPICAL MONSOON PATTERN IS EXPECTED NEXT WEEK...WITH AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS RETURNING TO THE REGION. && .DISCUSSION... UPPER LEVEL LOW PRESSURE WAS SITUATED OVER NORTH-CENTRAL ARIZONA THIS MORNING AS OF 0830Z...WITH THE MAJORITY OF THE STORM ACTIVITY WELL AHEAD OF THE LOW IN NEW MEXICO. WHILE THERE WERE A FEW SHOWERS NOTED ON RADAR BENEATH THE UPPER LEVEL DEFORMATION ZONE /LOCATED APPROXIMATELY ALONG INTERSTATE 17/...THE STORMS FROM THURSDAY EVENING HAD LARGELY DISSIPATED ACROSS THE DESERTS. IN THE WAKE OF THIS STORM...TEMPERATURES WERE GENERALLY IN THE UPPER 60S TO LOWER 70S ACROSS THE DESERTS...APPROXIMATELY 10 DEGREES BELOW NORMAL FOR MID/LATE AUGUST. STRONG ISENTROPIC DESCENT IS EXPECTED ACROSS THE REGION TODAY AS THE TROUGH MOVES OUT OF THE AREA. BL MOISTURE WILL REMAIN SOMEWHAT ELEVATED AS 1000-700MB MEAN MIXING RATIOS WILL STILL LINGER IN THE 8-12 G/KG RANGE...HOWEVER THE LACK OF UPPER LEVEL SUPPORT SHOULD PRECLUDE MUCH IN THE WAY OF WIDESPREAD SHOWERS AND THUNDERSTORMS. GIVEN THE CLOSER PROXIMITY TO THE DEPARTING LOW...I WOULD EXPECT TO SEE A FEW POP-UP SHOWERS NORTH AND EAST OF PHOENIX WITH LITTLE OF CONSEQUENCE ACROSS THE DESERTS. THERE COULD ALSO BE SOME ACTIVITY ACROSS PORTIONS OF SOUTHEAST ARIZONA THAT GLANCES PINAL COUNTY...BUT THAT WOULD BE ABOUT IT. HI-RES WRF MODELS ALONG WITH THE HRRR PAINT A SIMILAR SOLUTION FOR TODAY. MORE SUBSTANTIAL BL DRYING IS EXPECTED THIS WEEKEND AS ALL OPERATIONAL MODELS SUGGEST MIXING RATIOS WILL DROP TO AROUND 3-4 G/KG ACROSS SOUTHEAST CALIFORNIA AND TO 6-8 G/KG ACROSS ARIZONA. WITH EVEN LESS UPPER LEVEL SUPPORT THIS WEEKEND...POPS WILL REMAIN SUBSTANTIALLY BELOW CLIMO THIS WEEKEND. NEXT WEEK WILL SEE A RETURN TO A MORE TYPICAL MONSOON SETUP AS HIGH PRESSURE SLIDES EAST AND LOW LEVEL WINDS TURN AROUND OUT OF THE SOUTHEAST. WHILE THERE ARE SOME DIFFERENCES IN THE MODELS REGARDING A TROUGH MOVING THROUGH UTAH BY THE MIDDLE OF NEXT WEEK...BOTH THE GFS AND EUROPEAN...AS WELL AS THE 12Z NAEFS INDICATE A NOTEWORTHY INCREASE IN MOISTURE ACROSS THE AREA MONDAY/TUESDAY NEXT WEEK. THIS COULD BE THE RESULT OF THE PASSAGE OF A TROPICAL SYSTEM WELL SOUTH OF THE GULF OF CALIFORNIA...OR IT COULD SIMPLY BE OUTFLOW DRIVEN FROM CONVECTION OVER SONORA. REGARDLESS...MIXING RATIOS EXPECTED TO RETURN TO THE 10-12 G/KG RANGE EARLY NEXT WEEK WHICH SHOULD SET THE STAGE FOR AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY THROUGH AT LEAST FRIDAY. TOUGH TO PICK OUT ONE ACTIVE DAY OVER ANOTHER...BUT POPS HAVE BEEN NUDGED TOWARD CLIMO /AND SLIGHTLY HIGHER EAST OF PHOENIX/ FROM TUESDAY THROUGH FRIDAY. AS FOR TEMPERATURES...THE BOUNDARY LAYER WILL STRUGGLE TO RECOVER TODAY AND TEMPERATURES SHOULD REMAIN BELOW NORMAL. SOME RECOVERY IS EXPECTED ON SATURDAY WITH A RETURN TO NORMAL TEMPERATURES EXPECTED SUNDAY THROUGH THE END OF NEXT WEEK. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... AN AREA OF SHOWERS AND A FEW LINGERING EMBEDDED THUNDERSTORMS WILL AFFECT THE PHOENIX TERMINALS THROUGH AROUND 06Z BEFORE GRADUALLY DIMINISHING AND LIFTING OUT OF THE AREA TO THE NORTHEAST. GUSTY OUTFLOW WINDS GENERALLY OUT OF THE SOUTHWEST WILL LAST INTO LATE EVENING...BUT DIMINISH CONSIDERABLY BY MIDNIGHT. NOW EXPECTING A DELAYED ONSET TO DOWNSLOPE EASTERLY WINDS...LIKELY NOT SWITCHING AROUND UNTIL 09-10Z. CIGS AT 10-12K FEET WILL LINGER THROUGH MUCH OF THE OVERNIGHT...BEFORE SCATTERING OUT AROUND DAYBREAK. AN ISOLATED SHOWER AND THUNDERSTORM THREAT WILL AGAIN BE POSSIBLE FOR FRIDAY AFTERNOON...BUT CONFIDENCE IN AFFECTING AREA TERMINALS IS FAIRLY LOW AT THIS POINT. SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH... THE UPPER LOW CENTER HAS PUSHED INTO SOUTHWEST ARIZONA WITH CLOUDS BEGINNING TO SCATTER OUT FROM WEST TO EAST ACROSS SOUTHEAST CALIFORNIA. A GENERAL WESTERLY WIND COMPONENT IS EXPECTED THROUGH THE OVERNIGHT. SKIES WILL LIKELY CLEAR OUT SOMETIME FRIDAY MORNING WITH ONLY SOME LINGERING HIGH CIRRUS POSSIBLE FOR THE REST OF FRIDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... QUIET WEATHER IS EXPECTED ON SUNDAY...HOWEVER HUMIDITIES WILL INCREASE AS WE GET INTO NEXT WEEK WITH A BIG JUMP EXPECTED ON MONDAY INTO TUESDAY. CONSEQUENTLY...THE CHANCES OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL STEADILY INCREASE THROUGH THE WEEK. THE GREATEST STORM CHANCES WILL BE IN THE USUAL LOCATIONS NORTH AND EAST OF PHOENIX...WITH LESSER CHANCES ACROSS THE DESERTS. AS FOR HUMIDITIES...OVERNIGHT RECOVERIES WILL BE GOOD THROUGH NEXT WEEK WITH NO MAJOR WIDESPREAD WIND EVENTS EXPECTED. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS AVIATION...KUHLMAN FIRE WEATHER...LEINS
AREA FORECAST DISCUSSION
NWS TAUNTON MA
147 AM EDT FRI AUG 22 2014 .SYNOPSIS... SHOWERS CONTINUING ACROSS WESTERN NEW ENGLAND OVERNIGHT INTO FRIDAY...DISSOLVING SOUTHWEST AS HIGH PRESSURE BUILDS IN FROM THE NORTH. HIGH PRESSURE OUT OF THE MARITIMES WILL BRING DRIER AND COOLER CONDITIONS THIS WEEKEND. MILDER TEMPERATURES WILL RETURN EARLY NEXT WEEK. UNSETTLED CONDITIONS MAY RETURN LATE WEDNESDAY OR NEXT THURSDAY AS A FRONT MAY APPROACH OUT OF QUEBEC. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 10 PM UPDATE... WV IMAGERY SHOWS WEAKENED UPPER LVL CUTOFF VORTMAX NOW SLIDING SE THROUGH NY INTO PA/NJ THIS EVENING. LATEST RAP ALSO SHOWS THAT AXIS OF LEFTOVER INSTABILITY RESIDES TO THE W AS WELL. HENCE WHY MUCH OF THE CONVECTIVE ACTIVITY IS TAKING ON A MORE N-S PROPAGATION THIS EVENING AND WHY ONLY LEFTOVER CONVECTION IN THE FORM OF LIGHT-MOD -SHRA ARE MAKING IT/S WAY INTO THE WRN ZONES. FEEL THIS WILL CONTINUE TO BE THE TREND MUCH OF THE NIGHT...ALTHOUGH EXPECT THAT THE BULK OF THE STRONGER CONVECTION IS LIKELY TO WEAKEN WITH THE LOSS OF HEATING. ELSEWHERE...FURTHER E...SPOTTY -SHRA CONTINUE TO FORM AHEAD OF THE VORTMAX ALONG AN AXIS OF 30+ K-INDEX VALUES SUGGESTIVE OF MODERATE COLUMN MOISTURE IN THE LOW-MID LVLS AND JUST ENOUGH CONDITIONAL INSTABILITY TO SUPPORT THE LIFT PROVIDED BY THE APPROACHING WAVE. THESE ARE LIKELY TO CONTINUE FORMING IN-SITU ACROSS THE REGION...SO AN AXIS OF HIGH CHANCE TO LOW LIKELY POPS WILL BE USED. SOME OF THESE ARE LIKELY TO HOLD TOGETHER INTO THE PROVIDENCE-BOSTON CORRIDOR AS WELL. PREVIOUS DISCUSSION... TONIGHT... LOW TRANSITIONS AS AN OPEN WAVE LOW TOWARDS THE SE. ACCOMPANYING MAIN CRUX OF ENERGY YIELDS ASCENT OF AVAILABLE MOISTURE FUELED BY A SW-PLUME OF HIGHER THETA-E AIR WRAPPING AHEAD OF THE LOW /1.5 PWAT AIRMASS/ CONVERGING AGAINST HIGH PRESSURE AND DRY AIR BUILDING SW BELOW H8. THIS YIELDS NW-SE ORIENTED AREAS OF F-GEN FORCING WITHIN THE LOW-LEVELS THAT WILL LIKELY PARENT WITH MID- LEVEL FORCING. A CONSENSUS WEIGHTING OF MODEL GUIDANCE PUTS THE LIKELIHOOD OF SHOWERS TOWARDS THE W/SW FORECAST ZONE WHICH WOULD BE EXPECTED BUT CAN NOT RULE OUT OF CHANCE OF SHOWERS ELSEWHERE. ONLY THE IMMEDIATE E/SE MAY BE SPARED OF WET WEATHER...BUT AM NOT HOLDING MY BREATH. LOW CONFIDENCE OF THUNDER WITH THE STABLE ENVIRONMENT. WILL NEED TO MONITOR FOR FOG AND LOW CLOUDS. HIGHEST CONFIDENCE IS IN AREAS OF STRONG LOW-LEVEL CONVERGENCE AND SHOWERS... ESPECIALLY ACROSS THE HIGHER TERRAIN. YET WITH E-ONSHORE FLOW DRIVING IN HIGHER DEWPOINT AIR...ALONG WITH THE GREATER CAPACITY FOR AREAS TO RADIATE EFFICIENTLY THE LAST COUPLE OF NIGHTS...FOG AND LOW CLOUDS MAY BE POSSIBLE FOR E/SE PORTIONS OF NEW ENGLAND. INCREASING CLOUDS FROM THE W MAY COMPLICATE THE MATTER. WILL GO WITH LOWS AROUND THE UPPER-50S TO LOW-60S WITH THE COOL SPOTS TO THE N/W WHICH BARELY SAW ANY SUN...AND THE E/SE IMMEDIATE INTERIOR. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... FRIDAY... WITH THE LOW SWUNG SE OF THE REGION...CUTOFF ENERGY WRAPS REARWARD AND SE INTO THE REGION INVOKING A HANGING TROUGH. RISING HEIGHTS IN WAKE OF THE TROUGH ALLOW FOR ENHANCED RIDGING OF HIGH PRESSURE SW AHEAD OF WHICH F-GEN FORCING IS MAXIMIZED WITHIN THE LOW-LEVELS. PARENTING WITH MID-LEVEL ASCENT PER CUTOFF ENERGY...THERE IS THE LIKELIHOOD FOR CONTINUED SHOWERY WEATHER OVER SW PORTIONS OF NEW ENGLAND. WILL HOLD WITH LIKELY POPS ACROSS FAR W/SW PORTIONS OF THE FORECAST AREA BENEATH AN ABUNDANCE OF CLOUDS. AM NOT GOING TO GET SPECIFIC WITH THE FORECAST POPS BUT RATHER BROAD BRUSH AN AREA WHERE THERE IS HIGHEST CONFIDENCE. CHANCE TO SLIGHT CHANCE POPS E. COMBINATION OF CLOUDS AND RAIN COULD MAKE FOR A VERY CHILL DAY ESPECIALLY FOR MID- TO LATE-AUGUST. THE DREARY WEATHER COULD YIELD HIGHS AROUND THE LOW- TO MID-60S FOR THE S/W...WARMER E WHERE THE GREATER CHANCE OF SEEING SOME SUNSHINE YET ONLY INTO THE UPPER-60S WITH THE BRISK ONSHORE E-FLOW SURGING INTO INTERIOR NEW ENGLAND. FRIDAY NIGHT... ACTIVITY SHOULD DIMINISH WITH SUBSIDENCE AND DRY AIR BUILDING SW AS HEIGHTS RISE IN RESPONSE TO THE HANGING TROUGH SWINGING S/E. LOW- LEVEL F-GEN FORCING AND MID-LEVEL FORCING SHOULD CONTINUE TO PUSH SW INTO NY/PA AHEAD OF CONTINUED RIDGE ENHANCEMENT. WHILE CONSENSUS WEIGHTING OF MODEL GUIDANCE YIELDS A SLIGHT CHANCE OF SHOWERS FOR S/W PORTIONS OF THE FORECAST AREA...THE LONG E-FETCH OFF THE WATERS LIKELY RESULTING IN MOISTURE POOLING WITHIN THE LOW- LEVELS COULD RESULT IN LOW CLOUDS AND FOG...PERHAPS EVEN DRIZZLE AS THE FLOW UNDERGOES OROGRAPHIC LIFT ALONG THE E-SHORELINE. A TOUGH FORECAST AND A LIKELY COOL AND DREARY NIGHT WITH LOWS GETTING DOWN AROUND THE MID-50S. WITH DEWPOINTS AT SIMILAR VALUES... ANTICIPATING A PLETHORA OF PATCHY DENSE FOG WHERE THE E-FLOW IS LIGHT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THIS PERIOD * MILDER TEMPERATURES WILL RETURN MONDAY AND TUESDAY AS RIDGE TRIES TO BUILD EAST * TIMING OF APPROACHING FRONT BY LATE NEXT WEEK REMAINS UNCERTAIN BLOCKING UPPER LEVEL PATTERN LOOKS TO REMAIN IN PLACE ACROSS NORTH AMERICA AS H5 CUTOFF LOW PRES REMAINS PERSISTENT S OF GREENLAND THROUGH MOST IF NOT ALL OF THE LONG TERM PERIOD. SOME QUESTIONS DO COME INTO PLAY AS THE NORTHERN STREAM UPPER FLOW TRIES TO RECONFIGURE EARLY NEXT WEEK. NW FLOW TRIES TO FLATTEN OUT LATER THIS WEEKEND...THEN UPPER LEVEL RIDGING APPEARS TO BUILD IN BRIEFLY AROUND MONDAY OR TUESDAY. OPERATIONAL MODEL RUN DIFFERENCES MAY BE RESOLVING...BUT STILL SOME TIMING ISSUES CONTINUE LATE NEXT WEEK. THIS LENDS TO LOWER FORECAST CONFIDENCE BEYOND TUESDAY. DETAILS... SATURDAY AND SUNDAY... EXPECT HIGH PRES RIDGING TO CONTINUE TO NOSE IN FROM THE MARITIMES. THE ORIENTATION OF THIS RIDGE WILL KEEP COOL ONSHORE WINDS. SEVERAL OPERATIONAL MODEL SOLUTIONS...MAINLY THE 12Z GFS/ECMWF...TRY TO WORK CLOUDS AND SOME LIGHT PRECIP OFF THE OCEAN DURING SAT WITH LONG FETCH OFF THE GULF OF MAINE. CAN NOT RULE OUT ISOLD SHOWERS THAT MAY MOVE ONSHORE SATURDAY MORNING THEN PUSH W. COULD EVEN SEE SOME LIGHT DRIZZLE AROUND SUNRISE ALONG THE IMMEDIATE COAST. HAVE MENTIONED ONLY SLIGHT CHANCE POPS AT THIS POINT...THOUGH...BECAUSE OF UNCERTAINTY OF HOW MUCH MOISTURE WILL BE REALIZED. ONE CERTAINTY THOUGH IS THAT COOLER THAN NORMAL TEMPS WILL REMAIN WITH THE ONSHORE WINDS THROUGH THE WEEKEND. MONDAY AND TUESDAY... LOOKS LIKE THE MARITIMES RIDGE AXIS TRIES TO PUSH OFFSHORE AS H5 RIDGE PUSHES SE OUT OF ONTARIO AND THE GREAT LAKES AND ACTUALLY BUILDS INTO QUEBEC...A SET UP THAT HAS BEEN RARE THIS SUMMER. WILL REMAIN DRY BUT LOOKS LIKE MILDER TEMPS ON THE HORIZON AS WINDS BACK AROUND TO W AND SW. TEMPS LOOK BE CLOSE TO SEASONAL NORMS FOR LATE AUGUST...THOUGH WILL REMAIN A BIT COOLER ALONG THE S COAST. HUMIDITY WILL ALSO START TO INCREASE DURING TUESDAY. WEDNESDAY AND THURSDAY... WHILE THE LAST SEVERAL ECMWF OP RUNS HAVE BEEN MUCH FASTER THAN THE COUNTERPART GFS...THE 12Z RUN LOOKS MUCH CLOSER WITH ITS SOLUTION IN KEEPING RIDGING ACROSS MOST OF THE EASTERN SEABOARD. ONE BIG FLY IN THE OINTMENT IS THE POSSIBILITY OF A SYSTEM THAT WILL TRY TO MAKE THE TURN AROUND THE SUBTROPICAL RIDGE OFFSHORE...BUT THAT IS HIGHLY UNCERTAIN. WEAK COLD FRONT MAY STILL TRY TO WORK OUT OF QUEBEC LAST WED OR THU...THEN COULD STALL SOMEWHERE ACROSS THE REGION. STILL A TOUGH CALL. ALSO...DEPENDING UPON AVAILABLE MOISTURE AND INSTABILITY...MIGHT SEE SOME SHOWERS AND/OR THUNDERSTORMS IN VICINITY OF THE FRONT. LEANED TOWARD A BLEND OF THE 12Z GFS RUN ALONG WITH GFS/EC ENSEMBLES FOR THIS PORTION OF THE FORECAST. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH SATURDAY...MODERATE CONFIDENCE. THROUGH 12Z... A FEW SHOWERS ACROSS THE REGION THROUGH THE MORNING...ESPECIALLY ACROSS SRN NH AND POINTS W OF THE WORCESTER HILLS. THESE ARE THE MOST LIKELY SPOTS TO EXPERIENCE MVFR CONDITIONS. VFR DOMINATES ELSEWHERE...EXCEPT ACK...WHERE IFR CIGS LINGER THROUGH THE MORNING. TODAY INTO TONIGHT... CONDITIONS IMPROVE TO VFR MOST LOCATIONS THROUGH THE DAY ALTHOUGH LOW VFR CIGS ARE LIKELY ESPECIALLY AREAS W OF THE WORCESTER HILLS. SHOWERS LINGER IN THIS REGION AS WELL. BY TONIGHT...SHOWERS DISSIPATE BUT THERE MAY BE MORE WIDESPREAD FOG IN THE W AND THE POSSIBILITY OF LOWER CIGS IN THE E. THEREFORE...COMPLEX OVERNIGHT SCENARIO...WHERE SOME OCCASIONAL MVFR/IFR CONDITIONS ARE POSSIBLE. SAT... CONDITIONS IMPROVE TO VFR ALL LOCATIONS EXCEPT MAYBE AREAS E OF THE WST-ORH-AFN...WHERE SOME MVFR CONDITIONS MAY LINGER INTO THE DAY IN LOW CIGS. BY AFTERNOON...LIKELY TO SEE VFR ALL LOCATIONS. KBOS TERMINAL...MODERATE CONFIDENCE. MAINLY VFR TODAY EXCEPT FOR OCCASIONAL SHOWERS EARLY THIS MORNING. OVERNIGHT...EASTERLY FLOW COULD YIELD A PERIOD OF LOW CLOUDS WITH MVFR/IFR CIGS POSSIBLE. SHOULD THESE BE ESTABLISHED...ITS POSSIBLE THEY LINGER INTO THE MORNING HOURS SAT. KBDL TERMINAL...MODERATE CONFIDENCE. MVFR/VFR MAY BOUNCE BACK AND FORTH THROUGH THE MORNING WITH SHOWERS. BY AFTERNOON...CONDITIONS IMPROVE TO VFR AND MAY STAY THAT WAY THEREAFTER. OUTLOOK...SATURDAY THROUGH TUESDAY... HIGH CONFIDENCE FOR VFR. LOW PROBABILITY OF PATCHY FOG WITH BRIEF LOCAL MVFR-IFR CONDITIONS EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH FRIDAY...MODERATE CONFIDENCE. NE-WINDS INCREASING IN RESPONSE TO INTERIOR LOW PRESSURE SHIFTING SE ACROSS THE WATERS WITH SOME MILD STRENGTHENING AS HIGH PRESSURE BUILDS IN FROM THE N. SUBSEQUENT PRESSURE-GRADIENT MAY YIELD SOME DECENT FETCH WITH GUSTS UP TO 20 KTS TO CAUSE SEAS TO RISE...BUT WILL HOLD AT 4 FEET. FEEL BRISK WINDS WILL DIMINISH FOG POTENTIAL YET LOW CLOUDS AND SHOWERS MAY BE AN ISSUE FOR AREAS TOWARDS THE SW. OUTLOOK...SATURDAY THROUGH TUESDAY... HIGH CONFIDENCE. EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA THROUGH THE PERIOD. THERE IS A CHANCE THAT E SWELLS COULD BUILD CLOSE TO 5 FT ON THE OUTER WATERS THIS WEEKEND WITH LONG E FETCH...EVEN WITH WIND SPEEDS LESS THAN 15 KT. MAY SEE PATCHY OVERNIGHT FOG REDUCING VISIBILITIES EACH NIGHT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...SIPPRELL/EVT NEAR TERM...DOODY/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...EVT AVIATION...DOODY/EVT MARINE...SIPPRELL/EVT
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
149 AM EDT FRI AUG 22 2014 .SYNOPSIS... A STRONG UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER MISSISSIPPI VALLEY/GULF COAST CONTINUE TO DOMINATE THE WEATHER ACROSS THE MIDLANDS AND CSRA. THIS WILL CONTINUE INTO FRIDAY. 88D REGIONAL RADAR COMPOSITE SHOWS DECAYING LINE OF SHOWERS MOVING SOUTHEAST ACROSS CENTRAL/EAST NC. THIS WAS ONCE A PART OF A LARGER LINE OF SHOWERS AND THUNDERSTORMS THAT BOTH THE HRRR AND WRF INDICATED WOULD WEAKEN THROUGH THE EVENING HOURS. SATELLITE LOOP SHOWS SOME DEBRIS CLOUDS FROM THIS CONVECTION THAT WILL BE SPREADING ACROSS THE REGION OVERNIGHT...ESPECIALLY ALONG THE NC/SC BORDER. OTHERWISE...SKIES WILL REMAIN MOSTLY CLEAR AND TEMPERATURES FALLING INTO THE LOWER/MIDDLE 70S BY SUNRISE. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS. MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO SLIGHT CHANCE DIURNAL TSTMS AT BEST DUE TO BUILDING RIDGE ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF FREE CONVECTION/HIGH CONVECTIVE TEMPS. MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /MONDAY THROUGH THURSDAY/... FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD...WITH EARLY MORNING MVFR POSSIBLE AT AGS/OGB. SOME CONVECTIVE DEBRIS CONTINUES TO CROSS THE REGION WITH MOSTLY CLEAR SKIES ACROSS THE SOUTHERN MIDLANDS AND CSRA. EXPECT THE DEBRIS CLOUDS TO LIMIT FOG POTENTIAL...HOWEVER THERE IS ENOUGH POTENTIAL TO INCLUDE A TEMPO GROUP FOR AGS/OGB BETWEEN 08 AND 12Z THIS MORNING. FOG WHICH DEVELOPS WILL RAPIDLY ERODE WITH SUNRISE WITH SOME DIURNAL CUMULUS FORMING THROUGH THE LATE MORNING AND AFTERNOON HOURS. CHANCES FOR CONVECTION AT THE TAF SITES REMAINS TOO LOW TO INCLUDE ATTM. WINDS THROUGH THE PERIOD WILL BE WEST TO NORTHWEST AT 7 KNOTS OR LESS. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
421 AM EDT FRI AUG 22 2014 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 235 AM EDT FRI AUG 22 2014 AN ACTIVE AND WARM WEATHER PATTERN WILL REMAIN IN PLACE THROUGH THE WEEKEND AS A RIDGE OF HIGH PRESSURE BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY. THIS WILL ALLOW VERY WARM AND HUMID AIR TO PUSH INTO THE OHIO VALLEY. MEANWHILE...SEVERAL UPPER LEVEL WEATHER DISTURBANCES ARE EXPECTED TO PUSH INTO NORTHERN AND CENTRAL INDIANA ALONG A LINGERING FRONTAL BOUNDARY. THIS WILL RESULT IN DAILY CHANCES FOR SHOWERS OR STORMS THROUGH THE WEEKEND. NEXT WEEK ANOTHER FRONTAL SYSTEM WILL BRING ADDITIONAL CHANCES FOR RAIN AND WILL EVENTUALLY BRING A RETURN TO NEAR AVERAGE TEMPERATURES. && .NEAR TERM /TODAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 SURFACE ANALYSIS EARLY THIS MORNING SHOWS A WARM FRONTAL BOUNDARY IN PLACE ACROSS NORTHERN AND CENTRAL INDIANA...STRETCHING FROM NEAR CHICAGO TO MUNCIE AND WINCHESTER. RADAR CONTINUES TO SHOW SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. ALOFT A RIDGE OF HIGH PRESSURE WAS IN PLACE OVER THE LOWER MISSISSIPPI RIVER VALLEY...ALLOWING FOR UPPER LEVEL WEATHER DISTURBANCES TO RIDE THE RIDGE AND SPILL ACROSS THE WARM FRONT ACROSS THE NORTHERN AND CENTRAL INDIANA...ALL THE WHILE BEING A TRIGGER FOR TSRA. MEANWHILE...A VERY WARM AND MOIST AIR MASS REMAINS IN PLACE ACROSS CENTRAL INDIANA WITH DEW POINTS IN THE UPPER 60S AND LOWER 70S. SKIES WERE CLOUDY...FILLED WITH DEBRIS FROM EARLIER CONVECTION. MAIN FORECAST CHALLENGE TODAY WILL BE POPS. GFS AND NAM AGREE TO AN AMPLIFICATION OF THE UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY TODAY...HOWEVER THIS WILL STILL RESULT IN MORE OF THE SAME AS THE UPPER FLOW WILL BE POISED TO SPILL ALONG THE LINGERING FRONTAL BOUNDARY ACROSS CENTRAL AND NORTHERN INDIANA. FORECAST SOUNDINGS ACROSS THE AREA TODAY CONTINUE TO SHOW PLENTY OF MOISTURE AVAILABLE WITH OVER 2 INCHES OF PRECIPITABLE WATER. FORECAST SOUNDINGS ALSO IMPLY CONDITIONAL INSTABILITY WITH CAPE IN EXCESS OF 200 J/KG...HOWEVER CONVECTIVE TEMPS ARE IN THE LOWER 90S...WHICH SEEM A LITTLE HIGH. CONFIDENCE REMAINS LOW IN ANY SPECIFIC TIMING FOR TSRA TODAY AS GFS AND NAM BOTH FAIL TO SUGGEST ANY SPECIFIC ORGANIZED WAVE TO PASS ALOFT. HRRR DOES SUGGEST CONVECTION ACROSS THE NORTHERN PARTS OF THE FORECAST AREA THIS MORNING...AN GIVEN THE LATEST RADAR TRENDS WILL STEER TOWARD THIS SOLUTION. HOWEVER GIVEN THE MOIST AIR MASS IN PLACE ALONG WITH THE LINGERING FRONTAL BOUNDARY...WILL KEEP POPS IN PLACE THROUGH THE DAY. AS FOR TEMPS...WITH CLOUDS AND POSSIBLE RAIN TODAY...WILL TREND TOWARD PERSISTENCE...WHICH SHOULD BE COOLER THAN MAVMOS. WARMER TEMPS WILL BE FOUND ACROSS THE SW FORECAST AREA WHERE POPS CHANCES AND CLOUDS WILL BE MUCH LESS...DUE TO PROXIMITY TO THE FRONT. && .SHORT TERM /TONIGHT THROUGH MONDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 GFS AND NAM SUGGEST LITTLE OVERALL CHANGE IN THE ONGOING PATTERN TONIGHT AND SATURDAY. THE UPPER RIDGE TO THE WEST CONTINUES TO ALLOW WEAK UPPER DISTURBANCES TO SPILL SOUTHEAST INTO INDIANA. THE WARM...HUMID AND CONDITIONALLY UNSTABLE AIRMASS REMAINS IN PLACE. FORECAST SOUNDINGS REMAIN DEEPLY SATURATED WITH VERY HIGH PRECIPITABLE WATER VALUES. LINGERING SURFACE BOUNDARY REMAINS IN PLACE ALSO. THUS WILL RAISE POPS TONIGHT AND ON SATURDAY AS THESE FEATURES CONTINUE TO REMAIN IN PLACE. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL CONTINUE TO TREND OF LEANING WARMER THAN MAVMOS ON LOWS AND COOLER ON HIGHS. ON SATURDAY NIGHT THROUGH MONDAY...THE UPPER RIDGE AXIS BEGINS TO DRIFT EAST...WHICH BEGINS TO ALLOW DRIER AIR TO ENTER THE FORECAST COLUMN. THE UPPER STEERING FLOW BEGINS TO SHIFT ANY RIDGE RIDING SHORT WAVES WELL EAST OF INDIANA. WITH ET DRIER AIR ARRIVING PRECIPITABLE WATER IN THE FORECAST SOUNDINGS FALLS TO LESS THAN 1.75 IN. ALSO 700MB TEMPS RISE TOWARD 10C...OFTEN A KEY CAPPING TEMPERATURE. THUS WILL TREND POPS AT OR BELOW MAVMOS ON SUNDAY THROUGH MONDAY. AS FOR TEMPS...WILL TREND HIGHS AND LOWS WARMER THAN MAVMOS GIVEN THE VERY WARM AIR MASS THAT IS EXPECTED ACROSS THE AREA. && .LONG TERM /MONDAY NIGHT THROUGH NEXT THURSDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 ENSEMBLES SUGGEST UPPER RIDGE INITIALLY OVER THE AREA AT THE BEGINNING OF THE PERIOD WILL EVENTUALLY GET SUPPRESSED BACK TO THE SOUTH AS AN UPPER TROUGH MOVES INTO THE NORTHERN MIDWEST OR GREAT LAKES BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST PRECIPITATION POTENTIAL WILL MOVE BACK INTO THE AREA STARTING NEXT TUESDAY AS UPPER RIDGE BEGINS TO FLATTEN OUT...WITH THE BEST CHANCES NEXT WEDNESDAY AND THURSDAY AS A FRONTAL SYSTEM ASSOCIATED WITH THE APPROACHING UPPER TROUGH MOVES IN. WILL KEEP CHANCE POPS GOING IN THE FORECAST FROM TUESDAY THROUGH NEXT THURSDAY. && .AVIATION /DISCUSSION FOR THE 220900Z KIND TAF UPDATE/... ISSUED AT 421 AM EDT FRI AUG 22 2014 THUNDERSTORM CLUSTERS CONTINUE TO DROP SOUTHEAST ACROSS NORTHERN ILLINOIS AND NORTHERN INDIANA. SHORT TERM MODELS SUGGEST 850MB FLOW INTO THE CLUSTERS MAY BEGIN TO WEAKEN OVER THE NEXT COUPLE OF HOURS...BUT STILL LOOKS LIKE A GOOD CHANCE FOR AN IMPACT AT KIND AFTER 221200Z-221300Z. PREVIOUS DISCUSSION FOLLOWS. ADDITIONAL SHOWERS WERE MOVING EAST ACROSS NORTHERN ILLINOIS EARLY THIS OVERNIGHT ALONG STATIONARY FRONT THAT EXTENDS SOUTHEAST ACROSS THE NORTHERN TAF SITES AND OVER AN UPPER RIDGE. THE 01Z RAPID REFRESH REFLECTIVITY PROGS LOOK REASONABLE BRINGING THIS ACTIVITY IN THE VICINITY OF THE NORTHERN TAF SITES OVERNIGHT. WILL GO WITH VCSH AT THE START OF THE 06Z TAFS AT LAF AND IND BASED ON RADAR AND LIGHTNING TRENDS AND THEN VCTS SHORTLY THEREAFTER. WILL ALSO KEEP VCTS AT LAF AND IND TOMORROW AFTER 20Z AS A COLD FRONT DROPS SOUTHEAST ACROSS NORTHERN ILLINOIS. CAP WILL LIKELY KEEP ACTIVITY TO SCATTERED AT THE OTHER SITES...TOO LITTLE COVERAGE FOR ANY THUNDERSTORM MENTION. COULD SEE SOME MVFR AND WORSE FOG OVERNIGHT AS WINDS BECOMING VERY LIGHT. OTHERWISE...SOUTH WINDS WILL BECOME SOUTHWEST AND WEST TOMORROW MORNING BUT STILL LESS THAN 10 KNOTS. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM...JAS AVIATION...MK/JAS VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSINDIANAPOLIS WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
235 AM EDT FRI AUG 22 2014 .UPDATE... THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM SECTIONS HAVE BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 235 AM EDT FRI AUG 22 2014 AN ACTIVE AND WARM WEATHER PATTERN WILL REMAIN IN PLACE THROUGH THE WEEKEND AS A RIDGE OF HIGH PRESSURE BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY. THIS WILL ALLOW VERY WARM AND HUMID AIR TO PUSH INTO THE OHIO VALLEY. MEANWHILE...SEVERAL UPPER LEVEL WEATHER DISTURBANCES ARE EXPECTED TO PUSH INTO NORTHERN AND CENTRAL INDIANA ALONG A LINGERING FRONTAL BOUNDARY. THIS WILL RESULT IN DAILY CHANCES FOR SHOWERS OR STORMS THROUGH THE WEEKEND. NEXT WEEK ANOTHER FRONTAL SYSTEM WILL BRING ADDITIONAL CHANCES FOR RAIN AND WILL EVENTUALLY BRING A RETURN TO NEAR AVERAGE TEMPERATURES. && .NEAR TERM /TODAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 SURFACE ANALYSIS EARLY THIS MORNING SHOWS A WARM FRONTAL BOUNDARY IN PLACE ACROSS NORTHERN AND CENTRAL INDIANA...STRETCHING FROM NEAR CHICAGO TO MUNCIE AND WINCHESTER. RADAR CONTINUES TO SHOW SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. ALOFT A RIDGE OF HIGH PRESSURE WAS IN PLACE OVER THE LOWER MISSISSIPPI RIVER VALLEY...ALLOWING FOR UPPER LEVEL WEATHER DISTURBANCES TO RIDE THE RIDGE AND SPILL ACROSS THE WARM FRONT ACROSS THE NORTHERN AND CENTRAL INDIANA...ALL THE WHILE BEING A TRIGGER FOR TSRA. MEANWHILE...A VERY WARM AND MOIST AIR MASS REMAINS IN PLACE ACROSS CENTRAL INDIANA WITH DEW POINTS IN THE UPPER 60S AND LOWER 70S. SKIES WERE CLOUDY...FILLED WITH DEBRIS FROM EARLIER CONVECTION. MAIN FORECAST CHALLENGE TODAY WILL BE POPS. GFS AND NAM AGREE TO AN AMPLIFICATION OF THE UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY TODAY...HOWEVER THIS WILL STILL RESULT IN MORE OF THE SAME AS THE UPPER FLOW WILL BE POISED TO SPILL ALONG THE LINGERING FRONTAL BOUNDARY ACROSS CENTRAL AND NORTHERN INDIANA. FORECAST SOUNDINGS ACROSS THE AREA TODAY CONTINUE TO SHOW PLENTY OF MOISTURE AVAILABLE WITH OVER 2 INCHES OF PRECIPITABLE WATER. FORECAST SOUNDINGS ALSO IMPLY CONDITIONAL INSTABILITY WITH CAPE IN EXCESS OF 200 J/KG...HOWEVER CONVECTIVE TEMPS ARE IN THE LOWER 90S...WHICH SEEM A LITTLE HIGH. CONFIDENCE REMAINS LOW IN ANY SPECIFIC TIMING FOR TSRA TODAY AS GFS AND NAM BOTH FAIL TO SUGGEST ANY SPECIFIC ORGANIZED WAVE TO PASS ALOFT. HRRR DOES SUGGEST CONVECTION ACROSS THE NORTHERN PARTS OF THE FORECAST AREA THIS MORNING...AN GIVEN THE LATEST RADAR TRENDS WILL STEER TOWARD THIS SOLUTION. HOWEVER GIVEN THE MOIST AIR MASS IN PLACE ALONG WITH THE LINGERING FRONTAL BOUNDARY...WILL KEEP POPS IN PLACE THROUGH THE DAY. AS FOR TEMPS...WITH CLOUDS AND POSSIBLE RAIN TODAY...WILL TREND TOWARD PERSISTENCE...WHICH SHOULD BE COOLER THAN MAVMOS. WARMER TEMPS WILL BE FOUND ACROSS THE SW FORECAST AREA WHERE POPS CHANCES AND CLOUDS WILL BE MUCH LESS...DUE TO PROXIMITY TO THE FRONT. && .SHORT TERM /TONIGHT THROUGH MONDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 GFS AND NAM SUGGEST LITTLE OVERALL CHANGE IN THE ONGOING PATTERN TONIGHT AND SATURDAY. THE UPPER RIDGE TO THE WEST CONTINUES TO ALLOW WEAK UPPER DISTURBANCES TO SPILL SOUTHEAST INTO INDIANA. THE WARM...HUMID AND CONDITIONALLY UNSTABLE AIRMASS REMAINS IN PLACE. FORECAST SOUNDINGS REMAIN DEEPLY SATURATED WITH VERY HIGH PRECIPITABLE WATER VALUES. LINGERING SURFACE BOUNDARY REMAINS IN PLACE ALSO. THUS WILL RAISE POPS TONIGHT AND ON SATURDAY AS THESE FEATURES CONTINUE TO REMAIN IN PLACE. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL CONTINUE TO TREND OF LEANING WARMER THAN MAVMOS ON LOWS AND COOLER ON HIGHS. ON SATURDAY NIGHT THROUGH MONDAY...THE UPPER RIDGE AXIS BEGINS TO DRIFT EAST...WHICH BEGINS TO ALLOW DRIER AIR TO ENTER THE FORECAST COLUMN. THE UPPER STEERING FLOW BEGINS TO SHIFT ANY RIDGE RIDING SHORT WAVES WELL EAST OF INDIANA. WITH ET DRIER AIR ARRIVING PRECIPITABLE WATER IN THE FORECAST SOUNDINGS FALLS TO LESS THAN 1.75 IN. ALSO 700MB TEMPS RISE TOWARD 10C...OFTEN A KEY CAPPING TEMPERATURE. THUS WILL TREND POPS AT OR BELOW MAVMOS ON SUNDAY THROUGH MONDAY. AS FOR TEMPS...WILL TREND HIGHS AND LOWS WARMER THAN MAVMOS GIVEN THE VERY WARM AIR MASS THAT IS EXPECTED ACROSS THE AREA. && .LONG TERM /MONDAY NIGHT THROUGH NEXT THURSDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 ENSEMBLES SUGGEST UPPER RIDGE INITIALLY OVER THE AREA AT THE BEGINNING OF THE PERIOD WILL EVENTUALLY GET SUPPRESSED BACK TO THE SOUTH AS AN UPPER TROUGH MOVES INTO THE NORTHERN MIDWEST OR GREAT LAKES BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST PRECIPITATION POTENTIAL WILL MOVE BACK INTO THE AREA STARTING NEXT TUESDAY AS UPPER RIDGE BEGINS TO FLATTEN OUT...WITH THE BEST CHANCES NEXT WEDNESDAY AND THURSDAY AS A FRONTAL SYSTEM ASSOCIATED WITH THE APPROACHING UPPER TROUGH MOVES IN. WILL KEEP CHANCE POPS GOING IN THE FORECAST FROM TUESDAY THROUGH NEXT THURSDAY. && .AVIATION /DISCUSSION FOR THE 220600Z TAF ISSUANCE/... ISSUED AT 1234 AM EDT FRI AUG 22 2014 ADDITIONAL SHOWERS WERE MOVING EAST ACROSS NORTHERN ILLINOIS EARLY THIS OVERNIGHT ALONG STATIONARY FRONT THAT EXTENDS SOUTHEAST ACROSS THE NORTHERN TAF SITES AND OVER AN UPPER RIDGE. THE 01Z RAPID REFRESH REFLECTIVITY PROGS LOOK REASONABLE BRINGING THIS ACTIVITY IN THE VICINITY OF THE NORTHERN TAF SITES OVERNIGHT. WILL GO WITH VCSH AT THE START OF THE 06Z TAFS AT LAF AND IND BASED ON RADAR AND LIGHTNING TRENDS AND THEN VCTS SHORTLY THEREAFTER. WILL ALSO KEEP VCTS AT LAF AND IND TOMORROW AFTER 20Z AS A COLD FRONT DROPS SOUTHEAST ACROSS NORTHERN ILLINOIS. CAP WILL LIKELY KEEP ACTIVITY TO SCATTERED AT THE OTHER SITES...TOO LITTLE COVERAGE FOR ANY THUNDERSTORM MENTION. COULD SEE SOME MVFR AND WORSE FOG OVERNIGHT AS WINDS BECOMING VERY LIGHT. OTHERWISE...SOUTH WINDS WILL BECOME SOUTHWEST AND WEST TOMORROW MORNING BUT STILL LESS THAN 10 KNOTS. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM...JAS AVIATION...MK/JAS VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSINDIANAPOLIS WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
145 AM EDT FRI AUG 22 2014 .SYNOPSIS... ISSUED AT 310 PM EDT THU AUG 21 2014 A SERIES OF UPPER LEVEL DISTURBANCES WILL MOVE ACROSS THE GREAT LAKES AND OHIO VALLEY REGIONS TONIGHT. THESE DISTURBANCES WILL INTERACT WITH A STALLED FRONTAL BOUNDARY ACROSS THE REGION AND ABUNDANT LOW LEVEL MOISTURE TO PRODUCE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT INTO EARLY FRIDAY. AN UPPER LEVEL RIDGE WILL BUILD INTO THE REGION FRIDAY NIGHT AND SATURDAY WITH HOT AND HUMID CONDITIONS...ALONG WITH THE POSSIBILITY OF ISOLATED THUNDERSTORMS. LOW TEMPERATURES TONIGHT WILL DROP INTO THE UPPER 60S AND LOWER 70S. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOWER TO MID 80S ACROSS CENTRAL LOWER MICHIGAN...TO AROUND 90 ACROSS NORTHEAST ILLINOIS AND CENTRAL INDIANA. && .UPDATE... ISSUED AT 142 AM EDT FRI AUG 22 2014 RADAR TRENDS CONTINUE TO EXPAND WITH A NARROW LINE OF SHOWERS/STORMS IN WEST INDIANA AND A LARGE CLUSTER OF STORMS MOVING ACROSS PORTIONS OF NORTHERN/CENTRAL ILLINOIS. THE INITIAL LINE WAS MOVING ESE WITH THE CLUSTER GENERALLY EAST AT ONLY AROUND 20 TO 25 MPH. SPC MESO ANALYSIS INDICATED UPWARDS OF 2000 J/KG OF MOST UNSTABLE CAPE (AN INCREASE OVER THE PAST FEW HOURS) WITH PRECIPITABLE WATERS OVER 2 INCHES AND CORFIDI VECTORS BARELY 10 KNOTS. THIS COMBINED WITH THE RECENT RAINFALL IN THE SW MAY LEAD TO AN INCREASED THREAT OF FLOODING IN SOME AREAS. WILL MONITOR OVER THE NEXT HOURS OR 2 TO SEE WHERE THE HEAVIEST PRECIP MAY TRACK AND DECIDE THE BEST COURSE OF ACTION FOR ANY HYDRO CONCERNS AS HRRR AND RUC SEEM TO POINT TOWARDS THE HEAVIEST RAIN REMAINING JUST TO THE NE OF THE GREATEST AREA OF CONCERN. ANOTHER GRID UPDATE WILL BE NEEDED TO REFLECT THE PREVIOUSLY MENTIONED CONCERN FOR EXPANSION OF ACTIVITY FURTHER NORTH. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 310 PM EDT THU AUG 21 2014 THE NEXT IN A SERIES OF SMALL SCALE SHORT WAVES ACROSS SOUTHEAST WISCONSIN WILL DROP EAST SOUTHEAST OVER THE NEXT FEW HOURS RESULTING IN INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS. CONVECTION EARLIER THIS AFTERNOON HAS STABILIZED CONDITIONS SOMEWHAT FOR SFC BASED PARCELS...BUT WELL-ESTABLISHED AXIS OF POOLED LOW LEVEL MOISTURE WILL ALLOW FOR MODERATE ELEVATED INSTABILITY AND SCATTERED THUNDERSTORMS. SHOWERS ALSO APPEAR TO BE FOCUSING LATE THIS AFTERNOON ON AXIS OF DIFFERENTIAL HEATING FROM VPZ-RCR-AOH. SHEAR PROFILES WILL BE STEADILY ON THE INCREASE OVER THE NEXT SEVERAL HOURS HOWEVER...AS BELT OF STRONGER UPPER LEVEL WESTERLIES OVERSPREADS THE SOUTHERN GREAT LAKES REGION. LIMITING FACTORS TO INSTABILITY SHOULD TEND TO MITIGATE SEVERE POTENTIAL OVER THE NEXT SEVERAL HOURS. NEXT UPPER LEVEL SHORT WAVE PROGRESSING THROUGH MEAN RIDGE ACROSS EASTERN IOWA/NORTHWEST ILLINOIS SHOULD ALLOW FOR CONTINUED BROAD ISENTROPIC ASCENT OVER LOW LEVEL BOUNDARY ACROSS THE REGION...WITH CONTINUED THUNDER CHANCES LATE EVENING INTO THE EARLY PORTION OF THE OVERNIGHT. SOME LOW END SEVERE POTENTIAL MAY EXIST IF UPSTREAM CONVECTION CAN CONGEAL LATER THIS EVENING...WHICH CANNOT BE RULED OUT GIVEN STRENGTHENING BACKGROUND SHEAR PROFILES. OTHER CONCERN FOR TONIGHT WILL BE POSSIBLE HYDRO IMPACTS. SHOWERS/STORMS EARLIER TODAY LAID OUT AN AXIS OF 1-2 INCH RAINFALL AMOUNTS FROM WESTERN STARKE COUNTY INTO GRANT COUNTY. THIS CORRIDOR SHOULD REPRESENT BEST OVERALL ELEVATED INSTABILITY TONIGHT...AND WITH LITTLE DISPLACEMENT OF NEARLY 2 INCH PWAT AXIS AND WARM CLOUD DEPTHS GREATER THAN 12K FT...CANNOT RULE SOME LOCALIZED HEAVY RAINFALL. WITH STILL SOME UNCERTAINTIES ON HOW UPSTREAM CONVECTION WILL EVOLVE TONIGHT...AND A FAIRLY SIZABLE TEMPORAL GAP FROM THIS MORNINGS HEAVY RAINFALL...HAVE OPTED TO HOLD OFF ON ANY HYDRO HEADLINES AT THIS TIME. AFOREMENTIONED IOWA SHORT WAVE WILL BECOME MORE SHEARED IN NATURE ACROSS THE OHIO VALLEY/SOUTHERN GREAT LAKES TONIGHT INTO EARLY FRIDAY MORNING AND PROVIDE BEST FORCING TO EASTERN PORTIONS OF THE AREA BY AFTERNOON. MID LEVEL HEIGHT RISES WILL SLOWLY BUILD IN FROM THE WEST DURING THE DAY ALSO...WHICH SHOULD TEND TO LIMIT CONVECTIVE COVERAGE ACROSS FAR WESTERN AREAS BY LATE AFTERNOON. HAVE MAINTAINED HIGH CHANCE POPS INTO FRIDAY MORNING...WITH GRADUALLY DIMINISHING POPS FROM WEST TO EAST DURING THE AFTERNOON. IF GOOD DEAL OF INSOLATION CAN BE REALIZED...TEMPERATURES COULD REACH INTO THE LOWER 90S ACROSS SOUTHWEST PORTIONS OF THE AREA LATE AFTERNOON...WITH HEAT INDICES PUSHING NEAR THE 100 DEGREE MARK. GREATER CLOUD COVER/PRECIP SHOULD ALLOW FOR HEAT INDICES REMAINING IN THE LOWER 90S ACROSS THE EASTERN HALF. && .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 PM EDT THU AUG 21 2014 UPPER LEVEL RIDGE WILL BUILD NORTHEAST INTO THE GREAT LAKES REGION THIS WEEKEND INTO EARLY NEXT WEEK WHICH WILL SUPPORT A TREND TOWARD HOT/MAINLY DRY WX. RETAINED LOW CHANCES FOR SHOWERS/STORMS FRIDAY NIGHT INTO SATURDAY...MAINLY SOUTHWEST WHERE LOW LEVEL THETA-E GRADIENT REMAINS ANCHORED AS COOLER EASTERLY DRAINAGE FLOW INTO OUR NORTHEASTERN ZONES LIMITS NORTHEAST MIX OF DIFFUSE INSTABILITY GRADIENT/BOUNDARY. PRECIP CHANCES REMAIN NONZERO INTO SUNDAY AND MONDAY GIVEN AN INCREASINGLY MOIST/UNSTABLE BOUNDARY LAYER...ALTHOUGH WARMING/DRYING ALOFT UNDER UPPER RIDGE AXIS SUGGEST HOLDING WITH A DRY FCST (10 POP) STILL THE WAY TO GO. GRADUAL EASTWARD DRIFT OF A WESTERN CONUS UPPER TROUGH INTO THE NORTH-CENTRAL US WILL EVENTUALLY FLATTEN UPPER RIDGE IN PLACE... WITH MOISTURE CHANNEL/THETA-E FOLD INTO THE LOWER LAKES SUPPORTING INCREASING CHANCES FOR SHOWERS/STORMS. MODELS CONTINUE TO DIFFER WITH TIMING/AMPLITUDE OF THIS FEATURE RESULTING IN LOW CONFIDENCE POP/TEMP FCST TUESDAY AND BEYOND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 130 AM EDT FRI AUG 22 2014 STORMY 3 TO 6 HOUR PERIOD LOOKS TO BE IN STORE FOR AT LEAST KSBN AND LIKELY KFWA (JUST DELAYED AN HOUR OR 2) AS CONVECTION CONTINUES TO EXPAND ACROSS FAR WESTERN INDIANA BACK INTO NORTHERN ILLINOIS. A DEVELOPING LINE OF SHOWERS/STORMS WILL DRIFT EAST AND IMPACT KSBN AROUND 7Z. A LARGER CLUSTER OF STORMS WAS LOCATED WEST OF KJOT AND WORKING EAST AND SOMEWHAT SE. THIS MAY AFFECT KSBN BUT THINK IMPACTS ON FWA COULD BE GREATER. HAVE HANDLED WITH TEMPO GROUPS FOR NOW AND WILL MONITOR COVERAGE. ADDITIONAL SHOWERS AND STORMS COULD DEVELOP JUST ABOUT ANY TIME THROUGH THE TAF PERIOD BUT WILL LEAVE ANY ADDITIONAL DETAILS OUT FOR NOW. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...FISHER SYNOPSIS...MARSILI SHORT TERM...MARSILI LONG TERM...STEINWEDEL AVIATION...FISHER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
329 AM CDT FRI AUG 22 2014 .SYNOPSIS... ISSUED AT 328 AM CDT FRI AUG 22 2014 LOFT...UPPER RIDGE PERSISTS OVER THE MISSISSIPPI VALLEY. SURFACE LOW NEAR KLSE THIS MORNING WITH A STATIONARY FRONT EXTENDING TO ITS SOUTHWEST INTO COLORADO AND ALSO TO ITS EAST INTO THE GREAT LAKES. THUNDERSTORMS THIS MORNING FUELED BY LLJ...WARM SECTOR DEW POINTS IN THE 70S...AND APPROACHING MCV. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 328 AM CDT FRI AUG 22 2014 AREA OF CONVECTION OVER SOUTHCENTRAL IOWA SHOULD PERSIST THROUGH SUNRISE AND AFFECT SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. SHORT RANGE MODELS INCLUDING THE HRRR AND RUC WEAKEN THE CONVECTION AFTER SUNRISE...WHICH MAKES SENSE GIVEN THE DIURNAL TREND OF THE LLJ. HOWEVER...MODELS HAVE TYPICALLY BEEN TOO QUICK TO SQUELCH CONVECTION...AND THUS BELIEVE IT WILL LINGER A BIT LONGER THAN PROGGED AND WILL HANG ON TO POPS IN THE SOUTHERN HALF OF THE CWFA LONGER THAN MESOSCALE MODELS WOULD SUGGEST. ANOTHER ROUND OF STORMS EXPECTED THIS AFTERNOON AS THE SURFACE LOW CONTINUES TO SAG EVER SO SLIGHTLY FARTHER SOUTH AND THE FRONT REMAINS STALLED OVER NRN MO/SRN IA. OF COURSE EXACT POSITIONING OF STORMS REMAINS UNCERTAIN...IN PARTICULAR WITH SO MANY BOUNDARIES AROUND. CURRENT THINKING IS THAT FAVORED AREA IS ALONG AND JUST SOUTH OF I80 WHERE THE 850 MB FRONT IS PROGGED TO SET UP. REGARDLESS OF EXACT LOCATION...EXPECT INTENSE RAINFALL RATES DUE TO HIGH PRECIPITABLE WATERS AT OR ABOVE 2 INCHES. ACTIVE WEATHER CONTINUES THROUGH TONIGHT WITH BOUNDARIES LINGERING AND POTENTIAL FOR UPPER WAVES COMING OUT OF THE WSW. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 328 AM CDT FRI AUG 22 2014 THE PERSISTENT RING OF FIRE PATTERN CONTINUES THROUGH THE WEEKEND PRESENTING A THREAT FOR HOT AND HUMID CONDITIONS OUTSIDE THE OCCASIONAL MESOSCALE CONVECTIVE COMPLEXES LIKELY TO IMPACT PARTS OF THE REGION. THE UPPER LEVEL RIDGE IS THEN EXPECTED TO BREAK DOWN AND SHIFT EASTWARD BY THE MIDDLE PART OF NEXT WEEK. THIS WILL ALLOW CANADIAN HIGH PRESSURE TO BUILD INTO THE AREA...RETURNING TEMPERATURES CLOSER TO LATE AUGUST NORMALS AND PROVIDING A PERIOD OF DRIER WEATHER. SATURDAY AND SUNDAY...LOW PRESSURE LIFTING NORTHEAST THROUGH THE NORTHERN PLAINS WILL LIFT THE LOW LEVEL BOUNDARY/WARM FRONT NORTHWARD THROUGH THE FORECAST AREA SATURDAY. THE ASSOCIATED WARM ADVECTION AND STRENGTHENING MID LEVEL CAP WILL LIMIT THUNDERSTORM CHANCES TO THE NORTHEAST HALF OF THE FORECAST AREA. WITH DEW POINTS EASILY IN THE LOWER TO MID 70S...VERY MUGGY CONDITIONS WILL CONTINUE. MAX TEMPERATURES WILL CONTINUE TO BE A CHALLENGE DUE TO UNCERTAINTY IN CONVECTIVE TRENDS AND ASSOCIATED CLOUD COVER. WITH SURFACE WINDS MORE SOUTHEASTERLY...WILL BIAS TOWARD THE LOWER END OF GUIDANCE WITH HIGHS FROM THE MID 80S NORTHEAST TO LOWER 90S SOUTH. THIS WOULD STILL RESULT IN HEAT INDEX READINGS NEAR TO JUST ABOVE 100 SOUTH OF I-80 IN THE AFTERNOON HOURS. SATURDAY NIGHT THROUGH SUNDAY...THE AREA WILL FALL INTO THE MORE DEEPLY MIXED BUT CAPPED WARM SECTOR WITH 850 MB TEMPERATURES SUPPORTIVE OF WIDESPREAD HIGHS IN THE UPPER 80S TO LOWER 90S AND POSSIBLY WARMER DEPENDING ON THE AMOUNT OF CLOUD COVER. THIS WOULD RESULT IN POSSIBLY ANOTHER DAY OF 100 PLUS HEAT INDEX VALUES AND MAY REQUIRE HEAT HEADLINES OVER AT LEAST THE SOUTH. MONDAY THROUGH THURSDAY...MODEL SOLUTIONS CONTINUE TO DIFFER IN THE TIMING OF THE BOTH THE INITIAL EARLY WEEK FRONTAL PASSAGE AND THE STRONGER COLD FRONT AROUND WED AND THU. THE ECMWF AND CANADIAN HAVE THE INITIAL FRONT PUSHING THROUGH INTO CENTRAL IL AND MO MONDAY...WHILE THE GFS HOLDS IT WELL TO THE NW. OUR FORECAST WILL CONTINUE A LOW CONFIDENCE BLENDED APPROACH WITH THUNDERSTORM CHANCES RETURNING LATE MONDAY AND CONTINUING THROUGH THURSDAY. THE PAST COUPLE RUNS WERE TRENDING TOWARD A GREATER LIKELIHOOD OF A DRY THURSDAY AS HIGH PRESSURE BUILDS IN. WARM TO VERY WARM AND CONTINUED HIGH HUMIDITY SUGGEST A POSSIBLE NEED FOR HEAT HEADLINES AT LEAST IN THE AFTERNOON HOURS FOR MONDAY AND TUESDAY WHERE HIGHS ARE MAINTAINED IN THE UPPER 80S TO LOWER 90S WITH OVERNIGHT LOWS HOLDING IN THE 70S FOR MUCH OF THE AREA. TEMPERATURES ARE TRENDING A BIT COOLER...FOR WED AND THU AS THE CONTINUITY IN SUCCESSIVE MODEL RUNS BACK THE TIMING OF THE PATTERN CHANGE AND PLACEMENT OF THE IN-COMING HIGH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1130 PM CDT THU AUG 21 2014 LATEST TAFS UPDATED TO FAVOR HRRR/RAP SOLUTIONS...WHICH ARE MODELING THE CURRENT DEVELOPING CONVECTION WELL. NOW THINKING STORMS WILL BE MOST PREVALENT AT KMLI/KBRL OVERNIGHT AND HAVE INTRODUCED 3-4 HOUR TEMPO GROUPS. MORE ISOLATED COVERAGE EXPECTED AT KCID/KDBQ WITH VCTS GROUPS SUFFICIENT. RECENT TRENDS ALSO SUPPORT POTENTIAL FOR PERIODS OF IFR CIGS AND/OR VSBYS AT KCID/KDBQ OVERNIGHT. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...RP KINNEY
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1148 PM CDT Thu Aug 21 2014 ...AVIATION UPDATE... .UPDATE... Issued at 732 PM CDT THU AUG 21 2014 Will be updating the forecast soon to remove the heat advisory as HI values have fallen below 105 already and temps will continue to cool. Am a little concerned that we may be dealing with convection across northern KS for much of the evening. A 00Z objective surface analysis suggests a weak trough axis or boundary has laid over more west to east into northeast KS and the outflow from convection over north central KS will likely help better define this boundary. Once the low level jet increases this evening, there could be enough lift along this boundary for scattered storms to fester through much of the night. This seems to be the idea anyways from the HRRR and RAP, although they may be a little to far south with the QPF. Not sure how long a downbust threat may last as cooling of the boundary layer should increase convective inhibition. But locally heavy rainfall could be a concern as models show more than enough moisture (PWs around 2 inches) available for moderate and heavy rainfall. With this in mind will have tweaked POPs up a little for at least this evening across north central and northeast KS. && .SHORT TERM...(This Evening through Friday) Issued at 356 PM CDT THU AUG 21 2014 At 3 PM, surface low pressure was situated over the Oklahoma panhandle...connected by a weak cold front to another surface low in southwest Minnesota. There was a second weak boundary, more of a moisture discontinuity extending from just north of Russel, KS to near Marysville, KS. immediately north of this moisture boundary, low-level convergence and the presence of deeper moisture/more instability have led to persistent showers and a few storms in southern Nebraska and extreme northern Kansas. Aloft, a stream of very weak disturbances were moving out of the desert southwest into the central Plains, and will continue to do so through tomorrow. Southwest flow aloft on the west side of an upper ridge has allowed for continuous warm advection and a very hot regime locally. Temperatures today have been in the upper 90s to lower 100s (with the exception of areas very close to the NE border where there have been more clouds) while dewpoints especially north and east have held in the lower 70s. This has led to heat index values in the 102 to 108 range with the highest values east. Have issued a heat advisory for northeast and east central KS where the highest T/Td combinations should be in place through this evening. This evening into tonight, will be watching a few features for potential thunderstorm development. The first is the frontal zone in north central KS. Surface based CAPE greater than 1000 J/kg is in place in the airmass just north of the weak boundary. Wind shear is rather weak, but between the ample afternoon heating of the boundary and what seems to be an incoming weak short wave trough, could see scattered thunderstorm development in north central KS. If storms can develop through early evening, the very steep low level lapse rates would support localized strong downbursts. However, severe potential appears low as there may not be sufficient lift/instability to support the precip loading needed for severe winds. Will need to monitor regardless as the depth of the steep lapse rates would support damaging winds with only moderate mid-level downdrafts. As the evening progresses, expect a low level jet to increase a bit with some weak convergence into north central KS and a zone of more aggressive moisture transport from south central into northeast KS. This may further support north central KS thunderstorms by around 03Z, and could support further development into northeast KS by late evening and early morning. The chances are slight for thunderstorms at any given point, and the potential for severe weather overnight appears even lower yet given the expected elevated nature of the storms. Friday is a bit uncertain regarding temperatures and potential heat headlines. This is mainly due to uncertainty in how long any scattered precip or remnant cloud cover will be over the area. The current forecast leans toward a mainly cloud-free late morning and early afternoon. This, along with slightly warmer 850 temps would suggest temperatures near or slightly warmer than Thursday with dewpoints near or slightly lower than Thursday. IF this scenario plays out, a heat advisory could be needed for parts of the area again, but given at least some potential for convective debris and lower temps, have not issued at this time. Will then look to late afternoon for more potential for scattered storm development, mainly in northern KS. .LONG TERM...(Friday Night through Thursday) Issued at 356 PM CDT THU AUG 21 2014 The mid-level pattern is expected to remain fairly unchanged Friday night into the weekend as models show the mid-level ridge staying anchored over much of the southeastern U.S. with the mid-level trough in place over the western U.S. Friday night into Saturday this mid-level trough currently over the Pacific Northwest is expected to deepen and dig southward along the western Rockies before a strong embedded shortwave trough lifts northeastward toward the Northern Plains Saturday night into Sunday. As this shortwave trough pivots northward, it will help to slowly push the stationary front that will remain stalled out over north central Kansas and along the Kansas/Nebraska border eastward through the forecast area Sunday into Monday. Ahead of this frontal passage, southwesterly surface winds will prevail as surface low pressure remains anchored over the High Plains. As a result, warm air advection will persist through the weekend with unseasonably hot conditions. Highs for Saturday are expected to reach into the mid/upper 90s with afternoon heat indices rising into the 98F to 102F degree range. As winds shift to the north with the frontal passage, a slight cool-down is expected by early next week with highs in the upper 80s to low/mid 90s on Monday. As for precipitation chances through this period, there is a chance for some isolated nocturnal showers and thunderstorms Friday night and Saturday night with the help of the low-level jet, primarily focused over north central Kansas and along the Kansas/Nebraska border. Thunderstorm chances increase by Sunday night into Monday with the frontal passage. Models continue to show this front lifting northward over the region as a warm front by Monday night, however there are still some model discrepancies with regards to just how far north this warm front will lift. At this time though, models seem to be trending toward much of the southern half of the forecast area being in the warm sector as this boundary will likely become stationary once again near the Kansas/Nebraska border through Tuesday night, so expect temperatures to warm up once again into at least the low/mid 90s and possibly into the upper 90s for some locations. Tuesday night into Wednesday we may see a repeat of events as models are showing the stationary boundary once again transitioning to a cold front that will progress eastward across the region as a stronger mid-level trough develops and deepens across the Rockies. This stronger trough should help to finally push this system east of the area mid-week, with increased precipitation chances Tuesday night and Wednesday followed by slightly cooler temperatures in the mid 80s to near 90 degrees. && .AVIATION...(For the 06Z TAFs through 06Z Friday Night) Issued at 1148 PM CDT THU AUG 21 2014 Am quite uncertain whether TS will hold together long enough to make it into MHK. Profiler data shows a 40KT low level jet from the south and southwest with the gust front approaching MHK from the northwest. Think if the gust front was not going to make it into the terminal, I`d be inclined to keep storms out of the forecast. However seeing some isolated stuff develop over Lincoln CO is good enough for me to add a VCTS thinking the gust front could provide enough lift for some elevated storms. For TOP and FOE, thinking is the further east the storms move, the more CIN the will encounter as they move into the heart of the mid level ridge axis. So will maintain a VFR forecast and continue to monitor convective trends. Confidence in any model solution is low as none have done a very good job with this evenings storms. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...Wolters SHORT TERM...Barjenbruch LONG TERM...Hennecke AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
325 AM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS IS CURRENTLY SLIDING SOUTHEAST ACROSS THE SOUTHERN HALF OF OHIO. THIS COMPLEX IS WEAKENING AS EVIDENCED BY THE WARMING CLOUD TOPS OVER THE PAST COUPLE OF HOURS. STILL...FEEL THAT THIS WILL SKIRT THE NORTHEASTERN PORTION OF THE FORECAST AREA WITH MEASURABLE RAINFALL IN THE 06 TO 10Z TIME RANGE...SO BEEFED UP THE POPS TO ACCOUNT FOR THIS FEATURE. UPDATES HAVE BEEN SENT. UPDATE ISSUED AT 1031 PM EDT THU AUG 21 2014 A NEW FORECAST UPDATE WAS JUST SENT OUT ADDRESSING THE POSSIBILITY OF THUNDERSTORMS MOVING FURTHER SOUTH INTO OUR FORECAST AREA LATER TONIGHT THAN PREVIOUSLY THOUGHT. BASED ON CURRENT SATELLITE AND RADAR IMAGERY...IT APPEARS THAT THE NORTHERN 2 OR 3 TIERS OF COUNTIES OF OUR FORECAST AREA COULD EXPERIENCE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LARGE THUNDERSTORM COMPLEX THAT IS CURRENTLY MOVING ACROSS PARTS OF CENTRAL INDIANA AND WEST CENTRAL OHIO. THE SKY COVER...PRECIPITATION PROBABILITY...WEATHER TYPE...AND PRECIPITATION AMOUNT FORECAST GRIDS WERE ALL UPDATED TO REFLECT CURRENT TRENDS AND THE LATEST HRRR FORECAST DATA. THE HAZARDOUS WEATHER OUTLOOK WAS ALSO UPDATED TO REFLECT THE NEW THUNDERSTORM PROBABILITIES AND THE FURTHER SOUTHWARD MOVEMENT OF THE STORMS THEMSELVES. UPDATE ISSUED AT 758 PM EDT THU AUG 21 2014 SOME SIGNIFICANT UPDATES WERE MADE TO THE FORECAST GRIDS FOR THE REST OF THE TONIGHT INTO EARLY TOMORROW MORNING. WILL BE ISSUING A NEW ZONE FORECAST PRODUCT WITH THE PREFIRST PERIOD FROM DAY SHIFT REMOVED. THE GRIDS AND THE TEXT FORECAST PRODUCT HAVE BOTH BEEN UPDATED TO REFLECT THE FACT THAT ALL PRECIPITATION HAS NOW MOVED OUT OF EASTERN KENTUCKY. THE LATEST NAM12 AND HRRR MODELS BOTH ARE KEEPING PRECIPITATION OUT OF THE AREA UNTIL 8 OR 9Z TONIGHT. BASED ON THIS...AND THE LATEST RADAR IMAGERY...WHICH HAS A LARGE THUNDERSTORM COMPLEX MOVING ACROSS NORTHERN INDIANA...IT APPEARS THAT THE MODEL DATA IS ON TRACK AND THAT THE STORMS CURRENTLY MOVING ACROSS INDIANA WILL STAY MOSTLY NORTH OF THE AREA AS THEY MOVE ACROSS SOUTHERN OHIO LATE TONIGHT AND EARLY TOMORROW. WE MAY SEE A FEW SHOWERS AND STORMS FIRE UP ALONG THUNDERSTORM OUTFLOWS IN OUR NORTHERNMOST COUNTIES ALONG AND NORTH OF I-64 AROUND 8Z TONIGHT. THE SKY COVER GRIDS AND FORECAST WERE ALSO UPDATED TO REFLECT CURRENT TRENDS OF PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE FORECAST AREA. CONSIDERING THE AMOUNT OF RAIN EASTERN KENTUCKY HAS RECEIVED THE PAST SEVERAL DAYS...AND WITH CLOUDS BREAKING UP A BIT TONIGHT...WE SHOULD STILL SEE AREAS OF FOG IN OUR VALLEYS. LOCATIONS THAT RECEIVED RAINFALL TODAY...INCLUDING RIDGETOP LOCATIONS SUCH AS THE JACKSON WEATHER OFFICE...COULD ALSO SEE SOME MVFR FOG OVERNIGHT. THE HAZARDOUS WEATHER OUTLOOK WILL ALSO BE UPDATED SHORTLY TO REFLECT THE LACK OF THUNDER THROUGH DAWN TOMORROW. A NEW SET OF ZONES WILL ALSO BE ISSUED SHORTLY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 324 AM EDT FRI AUG 22 2014 UPPER LEVEL RIDGING WILL REMAIN IN PLAY DURING THE DURATION OF THE EXTENDED...WITH HEIGHTS EXPECTED TO BUILD AS THE HIGH SHIFTS NEWARD ACROSS THE OHIO RIVER VALLEY. BUILDING HEIGHTS WILL THEN TRANSLATE TO RISING TEMPERATURES. HOWEVER...MID AND UPPER LEVEL WINDS WILL GENERALLY REMAIN OUT OF THE NORTH DURING THE FIRST FEW DAYS OF THE EXTENDED. THIS...COUPLED WITH CLOUD COVER THAT WILL HAMPER MAXIMUM SOLAR RADIATION...WILL KEEP HIGHS IN THE MID AND UPPER 80S THROUGH TUESDAY. TEMPS MAY THEN COOL DOWN A COUPLE DEGREES AFTER TUESDAY AS HIGH PRESSURE SITS OVERHEAD AND UPPER LEVEL HEIGHTS ASSOCIATED WITH THE RIDGE BECOME MORE STATIC. BASED ON THE LATEST FORECAST SOUNDINGS...WILL AGREE WITH PREVIOUS FORECAST THAT EACH DAY SHOULD POSE A SHOWER/THUNDERSTORM THREAT MAINLY IN THE AFTERNOON AND EVENING. AND GIVEN THE MID LEVEL DRYING FROM MONDAY ON...WOULDN/T BE SURPRISED IF SOME OF THESE STORMS PRODUCE SOME POTENTIAL HAIL. IN PROMISING NEWS...GIVEN THE RIDGING PATTERN IN PLACE...WE WILL EXPERIENCE NO BOUNDARY FORCING UNTIL VERY LATE IN THE FORECAST...SO THIS WILL HAMPER SOME OF THE BEST INSTABILITY AND WIDESPREAD INITIATION. WINDS WILL BE LIGHT AT THE SURFACE...AND REMAIN SO AS WE HEAD UP HIGHER INTO THE ATMOSPHERE. THAT BEING SAID...AFTERNOON CAPE VALUES WILL BE ABOVE THE 2K J/KG RANGE THROUGH MUCH OF THE EXTENDED...AND LAPSE RATES WILL RISE SLIGHTLY BY TUES/WED TO 6 TO 6.5 C/KM...SO AFTERNOON HEATING AND INSTABILITY MAY BE ALL THAT IS NECESSARY FOR SCATTERED CELL DEVELOPMENT EACH DAY. A BOUNDARY WILL FINALLY PUSH INTO THE AREA BY THURS/FRI DAY 7/8 /PER THE LATEST GFS MODEL RUN/. THIS WILL BRING A MORE WIDESPREAD CHANCE FOR RAIN AND THUNDERSTORMS ACROSS THE AREA. HOWEVER...THERE IS QUITE A BIT OF DISAGREEMENT IN THE EXTENDED MODELS THIS FAR OUT...SO DECIDED TO LEAN ON THE ALLBLEND FOR POPS AT THIS TIME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS WILL WEAKEN AS IT SKIRTS BY ACROSS NORTHEASTERN KENTUCKY BETWEEN 06 AND 10Z. THIS WILL LIKELY AFFECT A LINE FROM KSYM TO KSJS BETWEEN 07 AND 09Z. MVFR VISIBILITIES ALONG WITH SOME GUSTY NORTHWESTERLY WINDS UP TO AROUND 20 KTS WILL ACCOMPANY THE LEADING EDGE OF THE SHOWERS AND STORMS. EXPECT MVFR OR WORSE FOG WILL SET IN ACROSS THE REST OF THE AREA THROUGH DAWN...WITH IFR OR WORSE FOG RESTRICTED TO THE DEEPER VALLEYS...PARTICULARLY THOSE THAT SAW RECENT HEAVY RAINFALL. ONCE THE FOG BURNS OFF THROUGH AROUND 13Z...A RENEWED THREAT OF CONVECTION WILL RETURN...MAINLY DURING THE AFTERNOON HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...GREIF LONG TERM...JMW AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
159 AM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS IS CURRENTLY SLIDING SOUTHEAST ACROSS THE SOUTHERN HALF OF OHIO. THIS COMPLEX IS WEAKENING AS EVIDENCED BY THE WARMING CLOUD TOPS OVER THE PAST COUPLE OF HOURS. STILL...FEEL THAT THIS WILL SKIRT THE NORTHEASTERN PORTION OF THE FORECAST AREA WITH MEASURABLE RAINFALL IN THE 06 TO 10Z TIME RANGE...SO BEEFED UP THE POPS TO ACCOUNT FOR THIS FEATURE. UPDATES HAVE BEEN SENT. UPDATE ISSUED AT 1031 PM EDT THU AUG 21 2014 A NEW FORECAST UPDATE WAS JUST SENT OUT ADDRESSING THE POSSIBILITY OF THUNDERSTORMS MOVING FURTHER SOUTH INTO OUR FORECAST AREA LATER TONIGHT THAN PREVIOUSLY THOUGHT. BASED ON CURRENT SATELLITE AND RADAR IMAGERY...IT APPEARS THAT THE NORTHERN 2 OR 3 TIERS OF COUNTIES OF OUR FORECAST AREA COULD EXPERIENCE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LARGE THUNDERSTORM COMPLEX THAT IS CURRENTLY MOVING ACROSS PARTS OF CENTRAL INDIANA AND WEST CENTRAL OHIO. THE SKY COVER...PRECIPITATION PROBABILITY...WEATHER TYPE...AND PRECIPITATION AMOUNT FORECAST GRIDS WERE ALL UPDATED TO REFLECT CURRENT TRENDS AND THE LATEST HRRR FORECAST DATA. THE HAZARDOUS WEATHER OUTLOOK WAS ALSO UPDATED TO REFLECT THE NEW THUNDERSTORM PROBABILITIES AND THE FURTHER SOUTHWARD MOVEMENT OF THE STORMS THEMSELVES. UPDATE ISSUED AT 758 PM EDT THU AUG 21 2014 SOME SIGNIFICANT UPDATES WERE MADE TO THE FORECAST GRIDS FOR THE REST OF THE TONIGHT INTO EARLY TOMORROW MORNING. WILL BE ISSUING A NEW ZONE FORECAST PRODUCT WITH THE PREFIRST PERIOD FROM DAY SHIFT REMOVED. THE GRIDS AND THE TEXT FORECAST PRODUCT HAVE BOTH BEEN UPDATED TO REFLECT THE FACT THAT ALL PRECIPITATION HAS NOW MOVED OUT OF EASTERN KENTUCKY. THE LATEST NAM12 AND HRRR MODELS BOTH ARE KEEPING PRECIPITATION OUT OF THE AREA UNTIL 8 OR 9Z TONIGHT. BASED ON THIS...AND THE LATEST RADAR IMAGERY...WHICH HAS A LARGE THUNDERSTORM COMPLEX MOVING ACROSS NORTHERN INDIANA...IT APPEARS THAT THE MODEL DATA IS ON TRACK AND THAT THE STORMS CURRENTLY MOVING ACROSS INDIANA WILL STAY MOSTLY NORTH OF THE AREA AS THEY MOVE ACROSS SOUTHERN OHIO LATE TONIGHT AND EARLY TOMORROW. WE MAY SEE A FEW SHOWERS AND STORMS FIRE UP ALONG THUNDERSTORM OUTFLOWS IN OUR NORTHERNMOST COUNTIES ALONG AND NORTH OF I-64 AROUND 8Z TONIGHT. THE SKY COVER GRIDS AND FORECAST WERE ALSO UPDATED TO REFLECT CURRENT TRENDS OF PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE FORECAST AREA. CONSIDERING THE AMOUNT OF RAIN EASTERN KENTUCKY HAS RECEIVED THE PAST SEVERAL DAYS...AND WITH CLOUDS BREAKING UP A BIT TONIGHT...WE SHOULD STILL SEE AREAS OF FOG IN OUR VALLEYS. LOCATIONS THAT RECEIVED RAINFALL TODAY...INCLUDING RIDGETOP LOCATIONS SUCH AS THE JACKSON WEATHER OFFICE...COULD ALSO SEE SOME MVFR FOG OVERNIGHT. THE HAZARDOUS WEATHER OUTLOOK WILL ALSO BE UPDATED SHORTLY TO REFLECT THE LACK OF THUNDER THROUGH DAWN TOMORROW. A NEW SET OF ZONES WILL ALSO BE ISSUED SHORTLY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU AUG 21 2014 STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 159 AM EDT FRI AUG 22 2014 A COMPLEX OF THUNDERSTORMS WILL WEAKEN AS IT SKIRTS BY ACROSS NORTHEASTERN KENTUCKY BETWEEN 06 AND 10Z. THIS WILL LIKELY AFFECT A LINE FROM KSYM TO KSJS BETWEEN 07 AND 09Z. MVFR VISIBILITIES ALONG WITH SOME GUSTY NORTHWESTERLY WINDS UP TO AROUND 20 KTS WILL ACCOMPANY THE LEADING EDGE OF THE SHOWERS AND STORMS. EXPECT MVFR OR WORSE FOG WILL SET IN ACROSS THE REST OF THE AREA THROUGH DAWN...WITH IFR OR WORSE FOG RESTRICTED TO THE DEEPER VALLEYS...PARTICULARLY THOSE THAT SAW RECENT HEAVY RAINFALL. ONCE THE FOG BURNS OFF THROUGH AROUND 13Z...A RENEWED THREAT OF CONVECTION WILL RETURN...MAINLY DURING THE AFTERNOON HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...GREIF LONG TERM...KAS AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
402 AM EDT FRI AUG 22 2014 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE ALONG A STALLED FRONTAL BOUNDARY ACROSS THE MID ATLANTIC STATES LATE TODAY AND TONIGHT. THE FRONT WILL PUSH SOUTHWEST AS A COLD FRONT SATURDAY. HIGH PRESSURE WILL BUILD SOUTH FROM NEW ENGLAND INTO THE MID ATLANTIC THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... THIS WEEK HAS BEEN FAIRLY CUT/PASTE EACH DAY W/ THE CONDITIONS OF TEMPS...HUMIDITY...SKY CONDITIONS AND POPS. THIS MOIST AIRMASS WILL FINALLY UNDERGO A TRANSITION AND BEGIN TO EXIT THE REGION...BUT NOT UNTIL SAT EVE. TILL THEN...ANOTHER SIMILAR DAY TO AT LEAST THE LAST TWO IS EXPECTED FOR THE AREA. DEWPOINTS CONTINUE TO HOVER WITHIN THE 65-70F RANGE WHICH IS PLENTY HUMID AND PREVENTING OUR TEMPS FROM DROPPING BELOW THE 70F MARK FOR MANY AREAS. GROUND FOG/LOW STRATUS NOT AS DENSE OR PREVALENT AT THIS TIME COMPARED TO LAST NIGHT...EVEN W/ CALM WINDS AND ANOTHER DAY OF RAIN ACCUMULATION STRANDS ACROSS THE REGION. UPPER DEBRIS CARRIED OUT AHEAD OF DISSIPATED CONVECTION FROM THE NW HAS OVERCOME MUCH OF THE AREA AND LIKELY LIMITING FOG FORMATION. STILL EXPECTING A BRIEF FEW HRS OF LOW STRATUS JUST W/IN THE BOUNDARY LAYER TOWARD DAWN WHEN THE TEMPS ARE AT THEIR MIN AND RADIATIONAL EFFECTS FROM THE RISING SUN BEGIN TO TRANSITION THE NEAR SFC LAYER - BUT ONLY PATCHY DENSE VLY FOG OR STRAITED BANDS OF LOW STRATUS FOR LOCALIZED AREAS. OUR AREA IS SURROUNDED TO THE EAST AND WEST BY CONTINUED SHOWER AND TSTM ACTIVITY OVERNIGHT...W/ THE ERN STORMS HEADING OFF THE COAST AND ANOTHER BATCH APPROACHING THE CNTRL APLCNS. A LOCAL UPPER IMPULSE LIKELY KICKING-OFF ANOTHER ROUND OF CELLS IN A LINEAR FASHION FROM ERN OH DOWN INTO NRN WV. HRRR AND MOST OTHER LOCAL WRF MEMBERS CARRYING THIS ACTIVITY OVER THE MTNS BUT THEN QUICKLY DISSIPATE IT TO AN INNOCUOUS BATCH OF LIGHT STRATIFORM SHOWERS. LIKE THE PREV FEW DAYS...TODAY WILL BE MOSTLY DRY - THOUGH HUMID - AND DODGING SCT SHOWERS/ISLD TSTMS LATER THIS AFTN/EVE. THE EARLIEST ACTIVITY WILL DICTATE THE LATER ACTIVITY...W/ LOCALLY HEAVY DOWNPOURS EXPECTED AND GUSTY WINDS W/ THE STRONGER CELLS. THE 00Z 4/22 KIAD SOUNDING SHOWS GOOD LAPSE RATES IN THE LOW LEVELS AND MOIST ADIABATIC HEADING UP THRU THE REST OF THE COLUMN...MUCH MORE MOIST THAN 24HRS PRIOR. THIS PROFILE IS EXPECTED TO CARRY OVER FOR TODAY`S ACTIVITY BUT END UP MORE STABLE THAN THU`S...AND A LESS FAVORABLE WIND PROFILE. WINDS BELOW 10KFT MAY HAVE A BULK AND MEAN SHEAR OF ONLY AROUND 5KT W/ A MUCH STRONGER UPPER FLOW. A POTENT UPPER JET OF 80-100KT WON`T HELP LOW-TOP CONVECTION MUCH AND MAY IN-FACT SHEAR OFF TALLER CELLS. THE LACK OF GOOD MID/LOW LEVEL STEERING FLOW INCREASES THE POTENTIAL FOR FLOODING AND FLASH FLOODING IN LOCALIZED AREAS...W/ A REGIME THAT MAY ALLOW FOR TRAINING CELLS UNDER THE RIGHT CONDITIONS OR ALONG A PRE-EXISTING BOUNDARY. WILL KEEP THIS THE HIGHLIGHT IN THE HWO...WHICH WILL BE THE BIGGEST THREAT OUTSIDE OF A FEW STRONG/MARGINALLY SVR TSTMS. SUNSET WILL AGAIN BE THE START OF TSTM DISSIPATION W/ ONLY A HANDFUL OF SHOWERS CONTINUING TO SLIDE ACROSS THE AREA INTO THE LATE NIGHT HRS. DEWPOINTS WILL CONTINUE TO HOVER NEAR 70F FOR ANOTHER HUMID OVERNIGHT. BATCHES OF MID CLOUD DECKS WILL ALSO HELP SHELTER THE AREA AND KEEP OVERNIGHT LOWS MODERATED NEAR THE 70F MARK. TOWARD SUNRISE SAT...THE DYNAMIC TRANSITION WILL BEGIN TO TAKE PLACE OFF TO OUR NORTH AND EAST. THE UPPER LOW SITTING OVER THE GREAT LAKES FOR THE PAST COUPLE OF DAYS WILL BE ABSORBED INTO THE UPPER FLOW AND HELP DIG THE RETROGRADED PORTION OF AN UPPER TROUGH BACK OVER THE AREA ON SAT. THE LAST ARM OF THIS FEATURE WILL DRIFT ACROSS THE REGION DURING THE DAYTIME HRS AND BRING MORE SCATTERED SHOWERS AND TSTMS. HIGH TEMPS WILL BE THEIR COOLEST IN DAYS BUT STILL REACHING THE L80S BY MID AFTN. HOWEVER...THE INSTABILITY PROFILE WILL LOOK MORE LIKE THU`S...W/ SFC-BASED CAPES POTENTIALLY IN THE 1-1.5K RANGE W/ A COOLER UPPER LEVEL TEMP PROFILE FROM THE UPPER TROUGH PASSAGE. STABILITY MAY COME HOWEVER IN THE FORM OF AN ELY LOW LEVEL WIND...WHICH COULD LIMIT THE CONVECTIVE INITIATION POTENTIAL IF THE CAP IS TOO STRONG AND SFC TEMPS DON`T REACH THE APPROPRIATE LEVELS - ESPEC CLOSER TO THE BAY AND NEAR THE MASON-DIXON LINE. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... SFC HIPRES WL BE BLDG DOWN THE COAST SAT NGT-SUN. AS H5 RDG AXIS CONTS TO SHARPEN...DRIER AIR WL BE ENTRAINED...AND GRDLY ERODE THE LLVL MARITIME SATURATION. THAT WL HPPN FIRST ALONG I-95 SAT EVNG. THINK WE/LL NEED TO HOLD ONTO POPS FOR THE MTNS ALL NGT SAT. FIRST CLRG WL COME TO METRO BALT ELY SUN...AND WL SPREAD THAT TO THE SW ACRS THE REMAINDER OF THE CWFA THRUT THE DAY. SUNDAY WL BE A NICER DAY THAN SAT...EVEN FOR THE MTNS WHICH MAY AVG OUT AS PTSUN VS MOSUN /OR EVEN SUNNY/. SINCE ITLL BE CLDY...AND DEWPTS WL BE DROPPING THRU THE 60S...DIDNT LWR MIN-T AS MUCH AS I CUD HV. AM TAKING A RESERVED APPROACH...W/ MIN-T IN THE 60S AS WELL. DID GO ON THE COOLER EDGE OF MAXT GDNC FOR SUN...BUT BELIEVE PROLONGED ELY FETCH WL KEEP TEMPS FAIRLY CLOSE TO WATER TEMPS. && .LONG TERM /MONDAY THROUGH THURSDAY/... SFC HIPRES AND H5 RDG AXIS CONT TO BUILD OVER THE MID ATLC THRU THE XTNDD PD. FLOW WL BE LGT...BUT TEMPS WL GRDLY BE MODERATING BY MIDWEEK. A CDFNT DROPPING TWD THE AREA LT WK WL PROVIDE THE ONLY PCPN RISK DURING THE WORK WEEK. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... SOME AREAS OF GROUND/VLY FOG IN TYPICAL PIEDMONT AND COASTAL AREAS BUT NOT SEEING A DEVELOPING DENSE LOW CLOUD BANK EITHER ATTM. THE NEXT FEW HRS MAY SEE BATCHES OF LOW-END MVFR CIGS/VSBYS DEVELOP BUT LIKELY NOT IFR OR LOWER...OUTSIDE OF A BRIEF PERIOD. SKIES AFTER SUNRISE WILL AGAIN WAVER IN/OUT OF PARTLY SUNNY/MOSTLY CLOUDY SINCE WE STILL HAVE A MOIST ATMOS. SCATTERED SHOWERS AND LATE-DAY TSTMS POSSIBLE AGAIN ACROSS THE REGION. CONDS WILL IMPROVE AGAIN OVERNIGHT...THOUGH A FEW ISOLATED SHOWERS AND MORE DENSE CLOUD COVER IS EXPECTED INTO EARLY SAT W/ MORE SHOWER/TSTMS EXPECTED ON SAT. MAY HV SOME LOW CLDS OR PATCHY FOG TO START THE DAY SUN...OTRW VFR WL PREVAIL THRU TUE. && .MARINE... SCA CONDITIONS NOT ANTICIPATED TODAY OR TONIGHT. A FEW TSTMS POSSIBLE THIS AFTN/EVE OVER THE WATERS. ELY ONSHORE FLOW WILL STRENGTHEN INTO EARLY SAT...W/ SOME POSSIBLY MARGINAL SCA CONDITIONS ALONG THE WRN SHORES AND MAIN STEM OF THE MD BAY. ELY/NELY FLOW WL PREVAIL SAT NGT INTO SUN AS HIPRES DRAINS COOLER/DRIER AIR ACRS WATERS. GDNC SUGGESTS WNDS WL REMAIN AOB 15 KT DURING THIS TIME. WL GO THAT ROUTE IN THE FCST ATTM...BUT WUDNT BE SHOCKED IF A FEW HIER GUSTS APPROACHED SCA CRIT IN THE MAIN CHANNEL OF THE MID BAY. BYD THAT...WNDS WL LESSEN AS HIPRES BLDS. && .TIDES/COASTAL FLOODING... WATER LEVELS ONLY INCHES HIGHER THAN ASTRO NORMALS. SHOULD BE PROBLEM FREE FOR THE NEXT COUPLE OF DAYS. FLOW TURNS ONSHORE AGAIN THIS WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...GMS SHORT TERM...HTS LONG TERM...HTS AVIATION...GMS/HTS MARINE...GMS/HTS TIDES/COASTAL FLOODING...HTS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
307 AM EDT FRI AUG 22 2014 .SYNOPSIS... A FRONTAL BOUNDARY REMAINS NEARLY STATIONARY ACROSS THE AREA INTO THE UPCOMING WEEKEND. HIGH PRESSURE FROM NEW ENGLAND IS SLOW TO BUILD OVER THE REGION FROM SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPDATE THIS EVENING TO MAKE MINOR TWEAK TO TIMING AND LONATION OVERNIGHT POPS. MORE WIDESPREAD SHOWERS BREAKING OUT ACROSS CENTRAL VA ARE IN RESPONSE TO THE SHORTWAVE JUST MOVING INTO THE REGION FROM THE NW. THE RAP IS HANDLING THIS FEATURE AND FORCING VERY WELL. EXPECT THE PRECIP TO CONTINUE TO EXPAND SOMEWHAT IN COVERAGE AND SPREAD EAST ACROSS CENTRAL VA AND THEN THE COAST INCLUDING MD...EASTERN SHORE AND SOUTHEAST VA. THUNDER ACTIVITY WITH THIS SHOULD BE LIMITED THOUGH CANNOT RULE OUT A FEW RUMBLES ESPECIALLY ACROSS NORTH CENTRAL VA...MD AND THE EASTERN SHORE. OVERALL TEMP FORECASTS REMAIN ON TRACK. PREVIOUS DISCUSSION... THE CURRENT SURFACE ANALYSIS INDICATES WEAK BROAD LOW PRESSURE IN VICINITY OF THE GREAT LAKES WITH A BOUNDARY EXTENDING SOUTHWARD FROM E-CENTRAL PA THROUGH THE WESTERN SHORE OF THE CHESAPEAKE BAY. THUNDERSTORMS HAVE DEVELOPED ALONG THE BOUNDARY OVER PA AHEAD OF A ~100KT UPPER JET DIVING ACROSS THE ERN GREAT LAKES. SPC MESOANALYSIS INDICATES 35-40KT OF EFFECTIVE SHEAR FROM SE PA THROUGH THE LOWER MD ERN SHORE ALONG WITH AN AXIS OF 1500J/KG OF MLCAPE. THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE OVER THE ERN SHORE LATER THIS AFTERNOON INTO THE EVENING HOURS AS THE JET DIVES SE. A FEW STRONGER STORMS ARE POSSIBLE BASED ON FAVORABLE DYNAMIC AND THERMODYNAMIC PARAMETERS...WITH THE PRIMARY THREAT BEING STRONG WIND GUSTS. THE MAIN LIMITING FACTOR WILL BE RATHER WEAK LAPSE RATES. OTHERWISE...A CHC (30-40%) OF GENERAL THUNDER IS EXPECTED OVERNIGHT AS THE UPPER JET ENERGY PASSES OVER THE AREA AND THE SURFACE BOUNDARY REMAINS IN PLACE. LESS FOG IS EXPECTED DUE TO THE PRESENCE OF MID/UPPER LEVEL CLOUD COVER. OVERNIGHT LOWS SHOULD RANGE FROM THE UPPER 60S TO LOW 70S. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/... MID/UPPER NW FLOW REMAINS OVER THE REGION FRIDAY INTO THE WEEKEND. A MORE VIGOROUS WAVE DROPS THROUGH THE FLOW ACROSS THE AREA FRIDAY NIGHT. THIS WILL PROVIDE BEST CHC OF AND GREATEST AREAL COVERAGE OF SHOWERS/TSTMS ACROSS THE LOCAL AREA DURING THE SHORT-TERM PERIOD DUE TO MORE FAVORABLE/STRONGER UPPER JET SUPPORT. POCKETS OF MODERATE TO HEAVY RAIN ARE POSSIBLE GIVEN MODEST MOISTURE AND FAVORABLE UPPER SUPPORT. HIGH PRESSURE BUILDS OVER NEW ENGLAND SATURDAY AND SLOWLY PUSHES INTO THE REGION BY SUNDAY. THIS WILL PUSH THE REMNANT FRONT S OF THE AREA. CHC POPS WILL CONTINUE EARLY SATURDAY...WITH A STEADY DRYING TREND COMMENCING SATURDAY AFTERNOON FROM NNE-SSW AS THE HIGH BUILDS INTO THE REGION. HIGHS FRIDAY SHOULD BE MAINLY 85-90...AND THEN FROM THE LOW TO MID 80S SATURDAY (UPPER 70S ALONG THE ATLANTIC BEACHES)...WITH UPPER 70S TO LOW 80S SUNDAY. LOWS SHOULD BE IN THE UPPER 60S TO LOW 70S SATURDAY...AND IN THE 60S SUNDAY MORNING. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... EXTENDED FORECAST PERIOD WILL CONSIST OF MAINLY NE FLOW AS HIGH PRESSURE TO THE NORTH RIDGES SOUTH WHILE AN AREA OF LOW PRESSURE EMERGES FROM THE BAHAMAS. THIS PATTERN WILL MAINTAIN A COOLER MARITIME AIRMASS IN PLACE OVER THE AREA THROUGH WED BEFORE HIGH PRESSURE AT THE SURFACE AND ALOFT BEGIN TO CENTER THEMSELVES OVER THE FA. AT THIS POINT SUBSIDENCE WILL PREVAIL AND WILL HELP TO DRY THE ATMOSPHERE. PRECIP ALONG THE VA/NC COAST CAN NOT BE COMPLETELY RULED OUT DUE TO THE INFLUX OF MOISTURE NORTH AS THE SURFACE LOW FORMS TO THE SOUTH. THERE IS SOME MODEL DISCREPANCY IN REGARDS TO THE POSITION AND STRENGTH OF THE LOW OVER THE TROPICAL ATLANTIC. AND DUE TO THE LARGE DEGREE OF CHANGE IN MODEL RUNS...AT THIS POINT... WILL NOT MODIFY THE PREVIOUS FORECAST TOO MUCH. TEMPS WILL REMAIN BELOW AVERAGE FOR MUCH OF THE EXTENDED PERIOD WITH HIGHS AROUND 80 MON AND TUES...WARMING SLIGHTLY INTO THE MID 80S WED AND THUR. SEASONAL LOW TEMPS IN THE LOW TO MID 60S ARE LIKELY AS THE MARITIME AIRMASS WILL LIMIT SIGNIFICANT OVERNIGHT COOLING. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...A WARM FRONT EXTENDED FROM NEAR WASHINGTON DC THROUGH EASTERN VIRGINIA (BETWEEN RICHMOND AND HAMPTON ROADS) AND INTO EASTERN NORTH CAROLINA. WINDS WERE MAINLY FROM THE W/SW WEST OF THE BOUNDARY AND FROM THE E/SE TO THE EAST OF IT. THIS FRONT WILL MOVE TOWARD THE COAST OVERNIGHT. LOW PRESSURE MAY DEVELOP JUST OFF THE COAST TODAY WHICH WOULD HELP SHIFT THE WINDS BRIEFLY TO NW/N DURING THE DAY. SBY HAS A T/TD SPREAD OF AROUND 3 DEGREES AND WITH RAIN HAVING FALLEN LATE THURSDAY...THERE MAY BE SOME IFR/LIFR FOG THERE. AN OVERCAST HIGH CEILING SHOULD LIMIT FOG FORMATION AT OTHER LOCATIONS AND PRESENTLY NONE IS FORECAST AT THE OTHER TAF SITES. VCTS ALSO INCLUDED AT SBY. DRY CONDITIONS EXPECTED FOR MUCH OF THE MORNING...BUT AN UPPER LEVEL SHORT WAVE MAY BRING A ROUND OF TSTMS LATE IN THE DAY OR TONIGHT. OUTLOOK...THUNDERSTORM CHANCES CONTINUE INTO SATURDAY WITH DRY WEATHER FORECAST BEGINNING SUNDAY. MVFR/IFR DUE TO STRATUS OR FOG WILL BE A POTENTIAL A FEW HOURS AROUND SUNRISE THROUGH SUNDAY MORNING. && .MARINE... LOW PRESSURE FORMS ALONG A STATIONARY BOUNDARY THAT IS CURRENTLY POSITIONED OVER THE EASTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. THIS WEAK AREA OF LOW PRESSURE WILL MOVE OFF THE COAST FRIDAY AFTN. EARLY SAT MORNING...HIGH PRESSURE NOSES SOUTH FROM THE NORTHEASTERN US CAUSING A BACKDOOR COLD FRONT TO MOVE THROUGH THE AREA. ENERGY STREAMING SE WILL HELP FORM AN AREA OF LOW PRESSURE OFF THE CAROLINA COAST. THIS SYNOPTIC SETUP WILL ENHANCE THE PRESSURE GRADIENT ACROSS THE WATERS CAUSING NEAR SCA WIND GUST OVER THE BAY(18-20KT) AND THE COASTAL WATERS(23-25KT) ON SATURDAY. DUE TO THE WIND DIRECTION AND FETCH...EXPECT WAVES TO BUILD TO 4-6FT ACROSS MOST OF THE COASTAL WATERS LASTING EARLY SATURDAY THROUGH MONDAY NIGHT. HIGH PRESSURE BEGINS TO POSITION OVER THE AREA BY TUESDAY BUT LOW PRESSURE EMERGING FROM THE SOUTH MAY HELP TO MAINTAIN THE PRESSURE GRADIENT AND ONSHORE FLOW THROUGH WED. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...AJZ/ALB NEAR TERM...AJZ/JAO SHORT TERM...AJZ/ALB LONG TERM...DAP AVIATION...MAS/LSA MARINE...DAP
AREA FORECAST DISCUSSION
NWS DULUTH MN
337 AM CDT FRI AUG 22 2014 .SYNOPSIS... ISSUED AT 308 AM CDT FRI AUG 22 2014 MID LVL RIDGING CONTINUES OVER THE CWA EARLY THIS MORNING AS A BROAD AREA OF WEAK LOW PRESSURE SHIFTS SLOW EAST UNDERNEATH. LATEST RUC SHOWS A 925 LOW OVER WCTRL WISC WITH AN INVERTED SHEAR AXIS EXTENDING NORTHWEST TOWARDS KBJI AND KROX. THIS IS FOLLOWED BY A COLD FRONT STRETCHING FROM ERN MANITOBA SOUTH TO CENTRAL SODAK. MAIN STORY OVER CWA THIS MORNING IS TRAPPED MOIST LAYER... ABOUT 5K FT IN DEPTH...UNDERNEATH SUBSIDENCE INVERSION. BR/FG AND EVEN SOME DRIZZLE IS OCCURRING IN MANY AREAS. A FEW CONVECTIVE CELLS HAVE TRIED TO DEVELOP OVER SERN WISC ZONES IN AN AREA OF LOW LVL THETAE RIDGE AXIS. LIMITED INSTABILITY HAS ALLOWED FAIRLY SHORT TEMPORAL NATURE TO DEVELOPMENT. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 TODAY...FCST MDL SNDGS SUGGEST IT MAY TAKE QUITE SOME TIME TO DISSIPATE THE CANOPY OF STRATUS AND BR ACROSS THE REGION. COND PRES DEFICITS SHOW A TREND TO DIMINISHING BR BY 14/15Z....THEN A RELATIVELY SATURATED CLOUD LAYER FINALLY BREAKING AFTER 2PM. PRECIP CHC SEEMS QUITE LIMITED BY RIDGING ALOFT AND LACK OF LOW LVL FOCUS FOR CONVERGENCE. THE GREATEST OPPORTUNITY MAY ARISE IN THE AFTERNOON AHEAD OF APPROACHING FRONTAL BDRY PUSHING TOWARDS NWRN CWA. MID LVL WARMTH WILL LIMIT MUCH DEVELOPMENT UNTIL AFTERNOON AS 70H THERMAL COOLING COMMENCES OVER WRN CWA. TONIGHT...MID LVL RIDGE AMPLIFIES OVERHEAD TONIGHT IN RESPONSE TO UPSTREAM STRENGTHENING OF TROF OVER ROCKIES. FRONTAL BDRY WILL STALL NORTH AND WEST OF CWA HOWEVER ITS ASSOCIATED PREFRONTAL THETAE RIDGE WILL BE NEARBY. ALTHOUGH THE DRY FORECAST WAS CARRIED OVER FROM PREVIOUS FCSTR...WILL NEED TO WATCH FOR SOME DEVELOPMENT OF CONVECTION MAKING IT INTO NWRN CWA TONIGHT. TOMORROW...HEIGHT FALLS MOVE INTO WRN HIGH PLAINS WITH SFC LOW ORGANIZING OVER SODAK. A SWRLY MID LVL FLOW WILL BEGIN OVER THE CWA AS THE RIDGE AXIS SHIFTS EAST. SFC HIGH PRESSURE WILL INCREASE OVER LAKE SUPERIOR WITH DISTINCT ONSHORE COMPONENT TO BDRY LYR WIND. TOUGH FCST FOR PRECIP AS MAIN FOCUS APPEARS TO BE SHAPING UP OVER THE WRN CWA BY LATE IN THE DAY. CLOUDS/PRECIP FCST FOR NORTH SHORE BASED ON A COMBINATION OF TERRAIN LIFT AND A GRADUAL DEEPENING OF SYNOPTIC SCALE MOIST LAYER. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 THE STRONG SURFACE LOW WILL MOVE NORTH ALONG THE WESTERN MINNESOTA BORDER SATURDAY NIGHT AND SUNDAY MORNING...BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...MAINLY THE THE WESTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. HAVE GONE AHEAD AN INCREASED POPS TO CATEGORICAL THERE...WITH HIGH END CHANCE TO LIKELY POPS ELSEWHERE AS THE WARM FRONT MOVES NORTH ACROSS THE REGION. MODELS ARE GETTING CLOSE ENOUGH TOGETHER TO HAVE A FAIRLY HIGH CONFIDENCE...THOUGH THE TRACK IS STILL SOMEWHAT PROBLEMATIC. WITH THE SURFACE LOW MOVING NORTHEAST OF THE REGION SUNDAY AND SUNDAY NIGHT....A COLD FRONT IS DRAGGED THROUGH THE AREA. DEPENDING ON THE MODEL...THE TIMING DIFFERS...BUT EITHER WAY WE ARE LOOKING AT MORE CHANCE TO LIKELY POPS. THE ECMWF...WHICH IS FARTHER WEST THAN THE GFS IMPLIES WE MAY HAVE SOME POTENTIAL FOR SEVERE STORMS...AS THE FRONT COMES THROUGH LATER AND ALLOWS FOR HEATING DURING THE DAY TO BUILD INSTABILITY AHEAD OF IT. WILL HAVE TO WATCH THIS CAREFULLY IN THE NEXT FEW DAYS. HAVE GONE WITH SOME FAIRLY WARM HIGH TEMPS ON SUNDAY...BUT IF THE ECMWF WORKS OUT...THESE WILL NEED TO BE RAISED. THIS STORM LINGERS OVER WESTERN ONTARIO FOR MONDAY BEFORE MOVING OFF TO THE NORTHEAST MONDAY AFTERNOON AND NIGHT...KEEPING SOME CHANCE POPS GOING OVER THE AREA BOTH PERIODS WITH COOLER TEMPERATURES. OUR NEXT SIGNIFICANT STORM SYSTEM COMES BY ON TUESDAY THROUGH WEDNESDAY. MODELS ARE VARYING SIGNIFICANTLY BY THIS POINT...WITH THE THE GFS BRINGING AN AREA OF MODERATE TO HEAVY RAIN ACROSS THE FORECAST AREA...AND THE ECMWF KEEPING IT FARTHER SOUTH AND DRIER FOR US. FOR NOW HAVE GONE WITH A BLEND APPROACH WITH SOME CHANCE POPS AND WE WILL HAVE TO REVISIT WITH LATER FORECASTS. A STRONG SURFACE RIDGE BUILDS INTO THE AREA FOR WEDNESDAY NIGHT AND THURSDAY....BRINGING COOLER TEMPERATURES AND HOPEFULLY A BIT MORE SUNSHINE TO THE REGION. LOWS BY WEDNESDAY NIGHT AND THURSDAY NIGHT MAY DIP INTO THE 40S AGAIN FOR PORTIONS OF THE AREA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1240 AM CDT FRI AUG 22 2014 MAINLY IFR/MVFR CONDITIONS COVERED THE NORTHLAND AS OF LATE EVENING. CONDITIONS ARE EXPECTED TO LOWER TO IFR/LIFR OVERNIGHT IN FOG/STRATUS. VSBYS WILL IMPROVE FRIDAY MORNING...AND CEILINGS WILL GRADUALLY LIFT AS WELL. SOME AREAS WILL SEE VFR CONDITIONS BY MID TO LATE AFTERNOON. A WARM FRONTAL BOUNDARY SOUTH OF THE NORTHLAND WAS PARTIALLY RESPONSIBLE FOR SCATTERED SHOWERS AND A FEW THUNDERSTORMS AS WELL. THE COVERAGE OF THE SHOWERS/STORMS ARE EXPECTED TO WANE OVERNIGHT WITH A FEW POSSIBLE ON FRIDAY. UPPER LEVEL HEIGHTS WILL BUILD FRIDAY AND THAT SHOULD HELP LIMIT THE COVERAGE OF SHOWERS/STORMS FRIDAY INTO FRIDAY EVENING. MORE FOG/STRATUS WILL DEVELOP FRIDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... DLH 71 60 70 61 / 20 10 20 60 INL 76 56 76 58 / 30 10 30 70 BRD 79 61 75 64 / 10 10 50 70 HYR 80 61 78 64 / 20 10 40 60 ASX 71 59 73 62 / 20 10 20 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR LSZ142>146. && $$ SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...LE AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
314 AM CDT Fri Aug 22 2014 .SHORT TERM: (Through Sunday) Issued at 312 AM CDT Fri Aug 22 2014 Well it finally feels like summer. Heat index values yesterday afternoon topped out around 105 degrees in the immediate St. Louis Metropolitan Area where the EXCESSIVE HEAT WARNING remains in effect until Sunday evening. Elsewhere, heat indices remained within the 100 to 104 degree range, including locations across northeast Missouri and west central Illinois. Will be adding the northeast Missouri and west central Illinois counties to the HEAT ADVISORY to account for heat index values reaching longevity criteria of 100 degree heat index for four or more days. I expect that the longevity of the heat wave (now likely extending into next week) will lead to future extensions in time as confidence increases. Have introduced some low chance POPs for thunderstorms this afternoon and evening across the northern half of the CWA. Hard to ignore mesoscale model guidance suggesting a secondary warm front developing across the northern CWA by this evening as low pressure deepens across the Central Plains. Both 00Z 4KM NCEP and NSSL WRF runs depict an active late afternoon and evening across the northern CWA - with the potential for an outflow to move south toward I-70. Again, for now, I have only increased POPs so that there is a mention in the forecast. Day shift will have to reevaluate as HRRR and RAP comes into range later this morning. CVKING .LONG TERM: (Monday through Thursday) Issued at 312 AM CDT Fri Aug 22 2014 Hot and dry conditions extend into next week ahead of a cold front that is now forecast to arrive on Wednesday. This front should bring a chance of rain and utlimately cooler temperatures by Thursday. CVKING && .AVIATION: (For the 06z TAFs through 06z Friday Night) Issued at 1125 PM CDT Thu Aug 21 2014 VFR conditions are expected to continue over the next 24 hours outside of any convection. Some activity has developed over far south-central Iowa over and will have to be watched as some of these storms may approach KUIN. Left KUIN dry though for now as mid/upper level winds suggest aforementioned storms should move east and stay north of site. Otherwise...hot/humid weather to continue with winds by day out of the southwest and at night backing to a more southeasterly direction. Did add a VCTS group at KUIN for Friday evening as a warm front will move northeast with some convection firing near this boundary per latest model guidance. Specifics for KSTL: VFR conditions are expected to continue over the next 30 hours outside of any convection. Hot/humid weather to continue with winds by day out of the southwest and at night backing to a more southeasterly direction. Could be some widely scattered storms Friday afternoon as a boundary lifts to the north and east...but left out of TAF for now as probability of occurrence of a storm affecting the terminal is quite low. Gosselin && .PRELIMINARY POINT TEMPS/POPS: Saint Louis 98 80 99 80 / 10 20 5 5 Quincy 94 75 95 75 / 20 30 5 5 Columbia 97 75 98 74 / 10 10 5 5 Jefferson City 98 76 99 74 / 10 10 5 5 Salem 93 75 95 75 / 10 20 5 5 Farmington 96 77 97 75 / 10 10 5 5 && .LSX WATCHES/WARNINGS/ADVISORIES: MO...HEAT ADVISORY until 7 PM CDT Sunday FOR Audrain MO-Boone MO- Callaway MO-Cole MO-Franklin MO-Gasconade MO-Jefferson MO- Knox MO-Lewis MO-Lincoln MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby MO-St. Charles MO-St. Francois MO-Ste. Genevieve MO-Warren MO. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR St. Louis City MO-St. Louis MO. IL...HEAT ADVISORY until 7 PM CDT Sunday FOR Adams IL-Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL- Macoupin IL-Marion IL-Monroe IL-Montgomery IL-Pike IL- Randolph IL-Washington IL. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR Madison IL-St. Clair IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
338 AM CDT FRI AUG 22 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 320 AM CDT FRI AUG 22 2014 FOCUS IS THUNDERSTORM AND SEVERE WEATHER POTENTIAL. THE PATTERN ALOFT WAS DOMINATED BY A RIDGE IN THE NORTHERN PACIFIC...A TROUGH ALONG THE WEST COAST AND RIDGING FROM THE GULF COAST TO THE GREAT LAKES REGION. AT THE SURFACE...LOW PRESSURE WAS ORIENTED FROM NORTHEAST NM TO SOUTHERN MN...AND THE SFC TROUGH/WARM FRONTAL BOUNDARY WAS ACTIVE FOR CONVECTION DURING THE EVENING HOURS. AS WE HEAD THROUGH THE DAY TODAY...THE SURFACE LOW WILL DEEPEN AND LIFT NORTH ACROSS WESTERN KANSAS WITH THE WARM FRONTAL BOUNDARY ORIENTING NEAR THE KS/NEB STATELINE TOWARD EVENING. THE FRONTAL BOUNDARY COMBINED WITH A DECENT WAVE AS SEEN ON WV IMAGERY IN AZ...WILL LIFT NORTHEAST AHEAD OF THE MEAN UPPER TROUGH IN THE PACIFIC NORTHWEST AND AID IN INITIATING ANOTHER ROUND OF CONVECTION LATER TODAY/TONIGHT. HIGH INSTABILITY WILL EXIST ALONG AND NORTH OF THE FRONT WITH 4000 J/KG EXPECTED FM THE NEB/KS STATELINE NORTHWARD INTO SOUTHERN NEB. SHEAR PARAMETERS IN GENERAL AVERAGE 30KTS BUT INCREASE OVER 30KTS ACROSS OUR WESTERN ZONES IN CLOSER PROXIMITY TO THE SURFACE LOW. MODELS SUGGEST THE BRUNT OF THE CONVECTION WILL BE ACROSS WESTERN NEBRASKA AND KANSAS...BUT THE FRONTAL BOUNDARY HAS BEEN ACTIVE THE LAST COUPLE OF DAYS AND BELIEVE THIS WILL BE THE CASE TODAY. WITH THE HIGH INSTABILITY...GOOD SHEAR AND BOUNDARY IN PLACE...CONDITIONS WILL BE FAVORABLE FOR SEVERE THUNDERSTORMS WITH LARGE HAIL OF GOLF BALL SIZE OR GREATER POSSIBLE AND DAMAGING TSTM WIND GUSTS. CANNOT RULE OUT THE POTENTIAL FOR A TORNADO ESPECIALLY IN THE VICINITY OF THE FRONT OR NEAR SFC LOW. HIGH DPS AND PRECIPITABLE WATER VALUES OF AN IN INCH AND A HALF TO TWO INCHES WILL BRING THE POSSIBILITY OF VERY HEAVY RAINFALL/LOCALIZED FLOODING ESPECIALLY FOR LOCATIONS WHICH HAVE RECEIVED DECENT RAINFALL AMOUNTS THE LAST COUPLE OF DAYS. FFG IS STILL IN THE 2 TO 3 INCH RANGE SO NOT LOOKING FOR A LOT OF HYDRO ISSUES JUST YET. AFTERNOON TEMPERATURES WILL BE TOASTY SOUTH OF THE WARM FRONT IN KANSAS WITH READINGS WELL INTO THE 90S TO AROUND 100F...WHILE TO THE NORTH OF THE FRONT UPPER 80S TO LOW 90S ARE FORECAST. THE WARM FRONTAL BOUNDARY WILL LIFT NORTH TONIGHT WITH THE PROGRESSING UPPER WAVE...AND THE NOSE OF A 40KT LLVL JET ORIENTS ACROSS NORTHERN AND EASTERN NEB. THE THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE ALONG/NORTH OF THE FRONT DURING THE EVENING BEFORE LIFTING INTO NORTHERN NEB OVERNIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 320 AM CDT FRI AUG 22 2014 ALOFT: AMPLIFIED SW FLOW WILL DOMINATE THRU TUE WITH A TROF OVER THE WRN USA. THE MOST DYNAMIC EMBEDDED SHORTWAVE TROF WILL EJECT ACROSS THE NRN PLAINS SUN LEAVING A +TILT REMNANT TROF REMAINING IN ITS WAKE. THIS TROF WILL BECOME PROGRESSIVE AND SLIDE THRU HERE TUE-WED WITH DEAMPLIFICATION. THE EC/GEM/GFS/UKMET ARE IN GOOD AGREEMENT. AS FOR THE SHORTER WAVELENGTHS...PLEASE SEE THE 1213 AM MODEL DIAGNOSTIC DISCUSSION /PMDHMD/ FOR DETAILED MODEL ASSESSMENT. THE LOW CURRENTLY OVER THE DESERT SW WILL OPEN UP AND LIFT THRU HERE SAT. THE DIGGING/POTENT LOW OVER THE NRN ROCKIES WILL TAKE ON -TILT SUN /JUST NW OF THE FCST AREA/ AS AN 80 KT UPPER-LVL JET SWINGS AROUND ITS BASE. WSW FLOW FOLLOWS MON-TUE WITH THE LAGGING TROF MOVING THRU LATE TUE. SUBSIDENT NW FLOW MAY MOVE IN WED-THU. THE 12Z/00Z GEM AND NOW THE 00Z EC CUT-OFF A LOW AT THE BASED OF THE TROF WITH THE WESTERLIES BECOMING RE-ESTABLISHED OVER CANADA. SURFACE: LOW PRES AND A CONVECTIVELY ACTIVE WARM FRONT WILL BE LIFTING THRU THE FCST AREA SAT. A WEAK COOL FRONT WILL SLIDE THRU BEHIND IT SUN. A STRONGER SECONDARY FRONT WILL FOLLOW SUN NIGHT. THIS FRONT WILL BECOME STATIONARY ALONG THE KS-NEB BORDER MON UNTIL THE UPPER TROF MOVES THRU...SHOVING THE FRONT DOWN INTO THE SRN PLAINS TUE. CANADIAN HIGH PRES WILL ARRIVE WED WITH RETURN FLOW AND A NEW LEE-SIDE TROF DEVELOPING THU. HAZARDS: MULTIPLE EPISODES OF TSTMS ARE POSSIBLE SAT-TUE. HEAT BURSTS COULD BE A PROBLEM SAT NIGHT. AS OF NOW THERE ARE NO OBVIOUS THREATS OF SEVERE TSTMS...BUT THERE CERTAINLY WILL BE POTENTIAL. THE DAILY DETAILS... SAT: OVERNIGHT TSTM ACTIVITY SHOULD BE OFF TO THE N BY DAYBREAK. DOESNT LOOK LIKE MUCH LOW-LVL FORCING TO INITIATE AFTERNOON TSTMS AND THE LOW-LVL MOIST TONGUE WILL LIFT N WITH THE WARM FRONT. FCST NAM/EC/GFS SOUNDINGS MINIMAL CAPPING THOUGH. WE MAY ALSO BE TOO HIGH ON OUR FCST DWPTS BY 5F. FOR NOW HAVE A SLIGHT CHANCE OF A TSTM AFTER 4 PM. IF TSTMS DEVELOP THEY WILL BE HIGH-BASED AND GUSTY WITH CONVECTIVE CONDENSATION LVLS AROUND 10K FT. BREEZY FROM HWY 281 E AS MIXING RESULTS IN DOWNWARD TRANSFER OF THE LLJ. SAT NIGHT: STRONG CONVERGENCE AS THE COOL FRONT MOVES IN. AGAIN TSTM INITIATION IS HIGHLY UNCERTAIN. SO ONLY HAVE A SLIGHT CHANCE POP IN THE FCST. WITH SKINNY CAPE ABOVE 10K FT AND AN INVERT-V LOOK TO THE SOUNDINGS...HAVE TO WONDER IF HEAT BURSTS MAY BE A PROBLEM "IF" TSTMS CAN DEVELOP. SUN: COOL FRONTAL PASSAGE WITH COOL/DRY AIR ADVECTION. TEMPS DROP BACK TO NEAR NORMAL. LOOKING VERY NICE AND COMFORTABLE FOR OUTDOOR ACTIVITIES. SUN NIGHT: UPSLOPE FLOW COULD RESULT IN TSTMS JUST TO THE W OF THE FCST AREA. THE FCST COULD BE OVERDONE ON POPS. THE EC/GFS DO NOT AGREE ON THE LOCATION OF THE FRONT. BELIEVE THE EC/GEM FURTHER S POSITION IS BEST GIVEN THE STRENGTH OF THE SYSTEM ALOFT. MON: WEAK LEE CYCLOGENESIS RESULT IN THE FRONT LIFTING BACK N. SUBSTANTIAL TSTM/MCS ACTIVITY EXPECTED MON NIGHT AS THE LLJ IMPINGES ON THE FRONT AND WAA/FRONTOGENESIS DEVELOP. THIS HAS HEAVY RAIN POTENTIAL WRITTEN ON IT. GEM/EC/GFS QPF IS IMPRESSIVE WITH POCKETS OF 1-3". TUE: BELOW AVERAGE CONFIDENCE ON TEMPS. THERE COULD BE SUBSTANTIAL CLOUD COVER UNDERNEATH THE FRONT. CANT RULE OUT MORE TSTM ACTIVITY INTO TUE NIGHT AS THE STRONGER COOL FRONT MOVES IN. WED-THU: FAIR AND DRY. HOWEVER...WE ARE CARRYING A SLIGHT CHANCE OF TSTMS WED. THIS PROBABLY IS OVERDONE. COMFORTABLY BELOW NORMAL WED WITH TEMPS RETURNING TO NORMAL THU. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1216 AM CDT FRI AUG 22 2014 AT FIRST GLANCE...CONVECTION DURING THE REMAINDER OF THE NIGHT SHOULD REMAIN TO THE EAST OF THE TERMINALS BUT A HIT OR MISS STORM MAY STILL DEVELOP PRIMARILY TOWARDS KGRI IN THE VCNTY OF A LLVL BOUNDARY. WITH FAIRLY LIGHT WINDS AND IN PRESENCE OF LLVL MOISTURE FOG DEVELOPMENT IS POSSIBLE TOWARD MORNING WITH THE HRRR THE MOST ROBUST WITH DEVELOP ALONG THE PLATTE RIVER AND MORE SO FOR KGRI VS KEAR. WILL CONTINUE TO MONITOR TRENDS FOR THIS. A WARM FRONTAL BOUNDARY IS PROGGED TO STALL SOUTH OF THE TERMINALS THIS AFTERNOON THEN LIFT NORTHWARD THIS EVENING AND TONIGHT. THE FRONT WILL AGAIN BE THE FOCUS FOR SHOWERS AND STORMS AND SEVERE WEATHER IS POSSIBLE. BEST TIMING FOR CONVECTION IS DURING THE LATTER TAF HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...FAY LONG TERM...HALBLAUB AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1222 AM CDT FRI AUG 22 2014 .UPDATE... ISSUED AT 700 PM CDT THU AUG 21 2014 THE 18Z NAM HAS FAILED TO CAPTURE THE ONGOING CONVECTION ACROSS OUR SOUTHEASTERN FORECAST AREA AND IS ESSENTIALLY DRY THROUGH MIDNIGHT. HOWEVER...THE HRRR MODEL SEEMS TO BE CATCHING ONTO THINGS AND HAS BEEN GIVING FAIRLY REALISTIC SCENARIOS FOR HOW THUNDERSTORMS WILL EVOLVE THIS EVENING. BASED ON RADAR AND THE HRRR HAVE INCREASED POPS INTO THE LIKELY CATEGORY FOR MOST OF OUR KANSAS COUNTIES INTO NUCKOLLS...THAYER...AND FILLMORE COUNTIES. ALSO SLIGHTLY INCREASED POPS NORTH OF THE RADAR FINE LINE BOUNDARY THAT AT 7 PM WAS RUNNING FROM PHILLIPSBURG...TO BLUE HILL. THE LOW LEVEL JET WILL INCREASE THIS EVENING WITH THE NOSE OF THE JET RUNNING INTO OUR SOUTHERN FORECAST AREA. THE HRRR INDICATES THAT THUNDERSTORMS COULD FORM NORTH OF THE EXISTING THUNDERSTORMS LATER THIS EVENING IN PLACES LIKE HASTINGS AS THE LOW LEVEL JET INCREASES...BUT CONFIDENCE IN THIS IS STILL LESS THAN 50 PERCENT. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 341 PM CDT THU AUG 21 2014 MAP ANALYSIS INDICATES AN UPPER TROPOSPHERIC RIDGE OVER THE CENTRAL CONUS...WITH TROUGHS OVER THE WESTERN AND EASTERN CONUS. MAP ANALYSIS ALSO SHOWS A CLOSED UPPER TROPOSPHERIC LOW EMBEDDED WITHIN THE BASE OF THE WESTERN CONUS TROUGH. ENHANCED UPPER TROPOSPHERIC ENERGY EXTENDS FROM NORTH TO SOUTH ALONG THE WESTERN CONUS COAST...THEN NORTHEAST INTO THE NORTHERN PLAINS...AND FINALLY BACK TO THE SOUTHEAST ACROSS THE GREAT LAKES REGION. THAT BEING SAID...UPPER TROPOSPHERIC FLOW OVER OUR AREA REMAINS FAIRLY WEAK...ONLY MAXING OUT AT AROUND 35KTS NEAR 38000FT AGL PER RAP ANALYSIS DATA AT 12Z. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED RIDGE AND TROUGHS...AS WELL AS ENHANCED UPPER TROPOSPHERIC MOISTURE EXTENDING FROM HURRICANE LOWELL INTO THE SOUTHWESTERN CONUS. THIS TROPICAL MOISTURE HAS YET TO REACH THE CENTRAL PLAINS HOWEVER. AT THE SURFACE AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER SOUTHWESTERN MINNESOTA...AND AN ASSOCIATED SURFACE TROUGH EXTENDS SOUTHWEST FROM THE LOW INTO NEBRASKA AND KANSAS. AS OF 18Z THIS TROUGH WAS NOTED EXTENDING FROM NEAR KODX...TO NEAR KHDE...TO NEAR KHLC. THE RESULTANT LOWER TROPOSPHERIC WIND FIELD ACROSS OUR AREA REMAINS FROM THE SOUTH ACROSS EASTERN PORTIONS OF OUR CWA...BUT LOCATIONS FARTHER WEST/NORTHWEST...BEHIND THE TROUGH...ARE NOW REPORTING A NORTHERLY COMPONENT TO THE LOWER TROPOSPHERIC WIND FIELD. GUIDANCE SUGGESTS THE CLOSED UPPER TROPOSPHERIC LOW OVER THE WESTERN CONUS WILL EJECT FROM THE BASE OF THE LONG WAVE TROUGH AS A SHORT WAVE TONIGHT INTO FRIDAY...LIKELY MOVING INTO THE FOUR CORNERS REGION BY 00Z SATURDAY. AS A RESULT...SURFACE CYCLOGENESIS THEN EXPECTED OVER WESTERN KANSAS FRIDAY AFTERNOON. SO ALTHOUGH THE SURFACE TROUGH...CURRENTLY LOCATED OVER OUR AREA...WILL MAKE AN ATTEMPT TO MOVE EAST ACROSS THE AREA TONIGHT...THE TROUGH SHOULD EVENTUALLY BECOME STATIONARY IF NOT RETROGRADE SOMEWHAT AS IT STRENGTHENS INTO A WARM FRONT IN RESPONSE TO THE WESTERN KANSAS CYCLOGENESIS. THE LOWER TROPOSPHERIC WIND FIELD ACROSS THE SOUTH/SOUTHEASTERN ONE-HALF OF THE CWA WILL LIKELY REMAIN FROM THE SOUTH/SOUTHEAST THROUGH THE NEXT 24 HOURS...BUT LOCATIONS FARTHER NORTHWEST WILL LIKELY EXPERIENCE MORE OF A NORTHEASTERLY WIND FIELD. ANY OMEGA DERIVED FROM UPPER TROPOSPHERIC KINEMATICS SHOULD REMAIN ON THE WEAK SIDE THROUGH MUCH OF THE SHORT TERM FORECAST PERIOD. THAT BEING SAID...GUIDANCE DOES SUGGEST THE AXIS OF A ~50KT LOWER TROPOSPHERIC JET STREAK JUST ABOVE THE BOUNDARY LAYER WILL DEVELOP FROM CENTRAL KANSAS INTO SOUTHEASTERN NEBRASKA TONIGHT...BEFORE SHIFTING OFF TO THE EAST SOMEWHAT BY DAYBREAK FRIDAY. THERMAL ADVECTION ALONG THIS AXIS...AS WELL AS MOISTURE CONVERGENCE NEAR THE NOSE OF THE JET STREAK...SHOULD BE SUFFICIENT FOR PRECIPITATION PRODUCTION...ESPECIALLY ACROSS OUR SOUTHEASTERN CWA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS AND EC...AS WELL AS SIMULATED REFLECTIVITY FROM THE HRRR. GIVEN ALL THIS...WENT AHEAD WITH 20-30% POPS ACROSS MUCH OF THE CWA FOR TONIGHT...WITH THE HIGHEST POPS RELEGATED TO THE SOUTHEASTERN CWA. ANY PRECIPITATION THAT DOES DEVELOP TONIGHT SHOULD MOVE OFF TO THE EAST BY SUNRISE FRIDAY AS THE AXIS OF THE LOWER TROPOSPHERIC JET STREAK DOES THE SAME. THIS SHOULD PROVIDE A BREAK IN THE PRECIPITATION ACROSS OUR AREA FRIDAY MORNING INTO LATE FRIDAY AFTERNOON. BY LATE FRIDAY AFTERNOON AND INTO FRIDAY EVENING HOWEVER...THERMAL ADVECTION AHEAD OF THE APPROACHING UPPER TROPOSPHERIC SHORT WAVE SHOULD PROMOTE INCREASING OMEGA ACROSS THE REGION. THIS OMEGA...WORKING IN CONCERT WITH ENHANCED LOWER TROPOSPHERIC CONVERGENCE ALONG THE STRENGTHENING BAROCLINIC ZONE...MAY BE SUFFICIENT FOR THE DEVELOPMENT OF ISOLATED TO PERHAPS SCATTERED SHOWER AND THUNDERSTORM ACTIVITY. THIS IS A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS AND EC. GIVEN ALL THIS..WENT AHEAD WITH 20-50% POPS ACROSS THE CWA FRIDAY AFTERNOON AND EVENING...WITH THE HIGHEST POPS RELEGATED TO CENTRAL AND NORTHERN PORTIONS OF THE CWA IN CLOSEST PROXIMITY TO THE LOWER TROPOSPHERIC BAROCLINIC ZONE. FORECAST PROXIMITY SOUNDINGS FROM THE ACROSS THE CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST PARCELS ROOTED TO AROUND 800MB SHOULD HAVE 500-1000J/KG WITH ANY CONVECTION THAT IS REALIZED TONIGHT. GIVEN THIS...WILL GO AHEAD AND OUTLOOK THE POSSIBILITY FOR LARGE HAIL AND STRONG WIND GUSTS IN THE HWO FOR TONIGHT. TURNING TO FRIDAY AFTERNOON AND EVENING...THE NAM...OPERATIONAL GFS AND EC SUGGEST 0-1KM MLCAPE VALUES OF 1000-3000J/KG WILL BE IN EXISTENCE WITH DEEP-LAYER BULK SHEAR VALUES OF 15-30KTS. GIVEN THIS...SEVERE WEATHER IS A DEFINITE POSSIBILITY WITH ANY THUNDERSTORM THAT DOES DEVELOP AND AS A RESULT...WILL GO AHEAD AND OUTLOOK LARGE HAIL AND STRONG WIND IN THE HWO FOR LATE FRIDAY AFTERNOON AND FRIDAY EVENING. ALSO...LOCALLY ENHANCED LOWER TROPOSPHERIC HORIZONTAL VORTICITY ALONG THE AXIS OF THE BAROCLINIC ZONE COULD PROMOTE A THREAT FOR ISOLATED TORNADOES WITH ANY STORM THAT CAN LATCH ONTO THE BOUNDARY. GIVEN THIS...WILL ALSO OUTLOOK THE THREAT FOR ISOLATED TORNADIC ACTIVITY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 341 PM CDT THU AUG 21 2014 FRIDAY EVENING THROUGH THURSDAY. FORECAST CONCERN IN THE EXTENDED CENTERS ON CONTINUING RAIN CHANCES ALONG WITH SLIGHT COOLING TREND. BEGINNING FRIDAY EVENING...MODELS CONSISTENT WITH BIG PICTURE AS THEY HAVE AN UPPER LEVEL RIDGE OVER THE MISSISSIPPI RIVER VALLEY AND A LOW CENTERED OVER NORTH CENTRAL IDAHO. THE LOW OVER SOUTHERN CALIFORNIA AT PRESENT IS FORECAST TO EJECT OUT AHEAD OF THE MAIN PACIFIC NW CLOSED LOW AS A SHORTWAVE TROUGH AND SHOULD MOVE NORTHEAST AFFECTING THE CENTRAL PLAINS LATE FRIDAY EVENING. IT SHOULD HELP LIFT A SURFACE LOW AND ASSOCIATED WARM FRONT NORTH THROUGH NEB OVERNIGHT. THE NAM AND GFS STILL DIFFER SOME ON THE LOCATION BUT ARE SIMILAR IN LIFTING THE PRECIPITATION FROM OUR CWA INTO NORTHERN NEB OVERNIGHT. HEAVY RAIN IS POSSIBLE AS THE SYSTEM MOVES SLOWLY NORTH WITH PLENTY OF MOISTURE AVAILABLE. THE KS PORTION OF OUR CWA MAY REMAIN CAPPED AND MISS OUT ON THE ACTION...DEPENDING WHERE THE THUNDERSTORMS FIRST FIRE UP. ML-CAPE AND DEEP LAYER SHEAR APPEAR HIGH ENOUGH FOR SEVERE STORMS INTO THE EVENING...ALTHOUGH BETTER SHEAR PROGGED TO BE IN THE WESTERN PART OF NEB AS OF NOW. DECENT LOW LEVEL JET OF 30-40 KT ALSO FORECAST TO DEVELOP AND RIDE OVER WARM FRONT WHICH SHOULD HELP SUSTAIN STORMS. PLAN TO TRIM POPS FROM SOUTH TO NORTH OVERNIGHT. RAIN CHANCES SHOULD CONTINUE FOR THE WEEKEND WITH THE BEST TIME FRAME FOR RAIN BEING LATE AFTERNOON INTO THE NIGHT. THE UPPER TROUGH IS EXPECTED TO MOVE A BIT EASTWARD PUTTING US IN SOUTHWEST FLOW. MEANWHILE A COLD FRONT SHOULD STALL OUT AS IS BECOMES PARALLEL TO THE UPPER FLOW AND SHOULD BE SITUATED FROM THE EASTERN DAKOTAS TO SOUTHWEST KANSAS. RAIN CHANCES WILL DEPEND ON SEVERAL FACTORS INCLUDING FRONTAL CONVERGENCE...LOW LEVEL JET DEVELOPMENT...SHORTWAVE TROUGHS MOVING THROUGH...ETC. ONE THING THAT WILL NOT BE A CONCERN IS MOISTURE AS PRECIPITABLE WATER VALUES AVERAGE 150 PERCENT OF NORMAL DUE TO A GOOD SUBTROPICAL TAP. AS NOTED IN PREVIOUS AFD...RAIN CHANCES CONTINUE INTO THE EARLY PART OF NEXT WEEK AS THE UPPER TROUGH REMAINS WEST OF US AND VARIOUS SURFACE BOUNDARIES STALL OUT OVER THE AREA. THE LATEST GFS OPERATIONAL RUN IS MOVING IT THROUGH A LITTLE FASTER AS IT NOW HAS THE 500 MB TROUGH AXIS PASSING OUR CWA NEXT WED AFTERNOON. EC HAS ALSO COME IN LINE WITH THIS SOLUTION AND IS ACTUALLY ABOUT 12 HOURS FASTER THAN THE GFS. THIS A QUITE A DIFFERENCE FROM PREVIOUS EC WHICH DROPPED A SECOND LOW SOUTH BEHIND THE FIRST ONE AND DIDNT CLEAR THE SECOND LOW UNTIL NEXT SATURDAY. WILL HAVE TO KEEP AN EYE ON HOW THIS CHANGES OVER THE NEXT FEW DAYS...BUT IF LATEST SOLUTIONS ARE ON TRACK...COULD SEE THINGS DRY OUT A BIT NEXT WED INTO AT LEAST FRIDAY WHICH WOULD BE WELCOME NEWS FOR NEB STATE FAIR ATTENDEES. REGARDING TEMPERATURES...SOME COOLING EXPECTED ON SUNDAY WITH PASSAGE OF WEAK COLD FRONT AND THEN AGAIN ON WEDNESDAY AS MAIN TROUGH AND ANOTHER FRONT MOVES THROUGH. EXPECT HIGH TO BE IN THE LOWER 80S NORTH TO LOWER 90S SOUTH ON AVERAGE...ONCE AGAIN DEPENDING ON WHERE VARIOUS FRONTS STALL OUT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1216 AM CDT FRI AUG 22 2014 AT FIRST GLANCE...CONVECTION DURING THE REMAINDER OF THE NIGHT SHOULD REMAIN TO THE EAST OF THE TERMINALS BUT A HIT OR MISS STORM MAY STILL DEVELOP PRIMARILY TOWARDS KGRI IN THE VCNTY OF A LLVL BOUNDARY. WITH FAIRLY LIGHT WINDS AND IN PRESENCE OF LLVL MOISTURE FOG DEVELOPMENT IS POSSIBLE TOWARD MORNING WITH THE HRRR THE MOST ROBUST WITH DEVELOP ALONG THE PLATTE RIVER AND MORE SO FOR KGRI VS KEAR. WILL CONTINUE TO MONITOR TRENDS FOR THIS. A WARM FRONTAL BOUNDARY IS PROGGED TO STALL SOUTH OF THE TERMINALS THIS AFTERNOON THEN LIFT NORTHWARD THIS EVENING AND TONIGHT. THE FRONT WILL AGAIN BE THE FOCUS FOR SHOWERS AND STORMS AND SEVERE WEATHER IS POSSIBLE. BEST TIMING FOR CONVECTION IS DURING THE LATTER TAF HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...WESELY SHORT TERM...BRYANT LONG TERM...EWALD AVIATION...FAY
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
255 AM PDT FRI AUG 22 2014 .SYNOPSIS...A CIRCULATION OVER SOUTHWEST ARIZONA WILL CONTINUE TOWARD THE FOUR CORNERS REGION TODAY. A FEW LINGERING STORMS MAY OCCUR OVER NORTHWEST ARIZONA. A BROAD AREA OF LOW PRESSURE BRUSHING NORTHERN NEVADA WILL LEAD TO DRY CONDITIONS WITH TEMPERATURES A LITTLE BELOW NORMAL ACROSS THE ENTIRE REGION THROUGH THE MIDDLE OF NEXT WEEK. && .SHORT TERM...THROUGH SUNDAY NIGHT UPPER LOW OVER SOUTHWEST ARIZONA NOW WILL LIFT NORTHEAST INTO THE FOUR CORNERS THIS AFTERNOON IN RESPONSE TO TROUGH DIGGING INTO THE PACIFIC NORTHWEST. REGIONAL RADAR SHOWS SOME LIGHT RAIN AROUND FLAGSTAFF WITH NOTHING IN OUR FORECAST AREA. HRRR SUGGESTS CONVECTION WILL GET ANOTHER EARLY START (BY 10 AM) OVER THE HIGHER TERRAIN OF SOUTHERN MOHAVE COUNTY WHERE SUFFICIENT MOISTURE/INSTABILITY REMAIN. IT WILL BE MUCH QUIETER ACROSS SOUTHEAST NEVADA AND EASTERN SAN BERNARDINO COUNTY AS SOME DRYING AND STABILIZATION OF THE AIR MASS OCCURS. FOR FAR NORTHERN LINCOLN COUNTY, MODELS CONTINUE TO INDICATE THE POTENTIAL OF SOME SHOWERS/THUNDERSTORMS IN PROXIMITY OF A STATIONARY FRONT OVER CENTRAL NEVADA. ON SATURDAY, THE ONLY MENTIONABLE POPS ARE ACROSS NORTHEAST LINCOLN AGAIN NEAR THE STATIONARY FRONT. ELSEWHERE, DRYING FROM THE WEST WILL OCCUR OVER THE WEEKEND. DUE TO THE APPROACHING TROUGH SOUTH/SOUTHWEST WINDS WILL INCREASE ACROSS THE WESTERN MOJAVE DESERT AND SOUTHERN GREAT BASIN THIS AFTERNOON BUT WILL REMAIN BELOW ADVISORY CRITERIA. HI RES MODELS ALSO SHOWING A WEAK DOWNSLOPE EVENT ALONG THE EASTERN SIERRA SLOPES SAY BETWEEN 3 PM AND 10 PM THIS EVENING. PLEASANT TEMPERATURES TO THE START EACH DAY WHILE DAYTIME HIGHS WILL CONTINUE TO RUN AROUND 3 TO 6 DEGREES BELOW NORMAL. .LONG TERM...MONDAY THROUGH FRIDAY NIGHT. AFTER FLYING SOLO LAST NIGHT, THE OPERATIONAL ECMWF RETURNED BACK TO A PROGNOSTICATION MORE SIMILAR TO WHAT IT HAD BEEN SHOWING ON PREVIOUS MODEL RUNS FOR EARLY NEXT WEEK. THIS PUTS IT IN MUCH BETTER AGREEMENT WITH THE OTHER OPERATIONAL MODELS AND THE VAST MAJORITY OF THE GFS ENSEMBLE MEMBERS WITH HOW IT HANDLES THE UPCOMING PATTERN. THE NEXT MID/UPPER LEVEL TROUGH IS FORECAST TO DROP SOUTHEAST ACROSS NEVADA MONDAY AFTERNOON INTO MONDAY NIGHT AND INTO UTAH BY TUESDAY. THE 00Z OPERATIONAL GFS WAS MORE SHALLOW WITH THE TROUGH THAN THE GEM AND ECMWF SO THE FORECAST SHOWS A BLEND BETWEEN THE TWO. UNLESS THIS TROUGH ENTRAINS ENOUGH SUBTROPICAL MOISTURE INTO IT, IT SHOULD PASS ON BY WITH LITTLE MORE THAN SOME HIGH CLOUDS AND PERHAPS SOME ENHANCED WINDS. TEMPS SHOULD BE HELD DOWN A FEW DEGREES BELOW NORMAL DUE TO THE LOWER HEIGHTS, BY WEDNESDAY INTO THURSDAY, A RIDGE ALOFT IS SHOWN TO BUILD IN FROM THE WEST WHICH SHOULD YIELD A WARMING TREND WITH HIGHS EDGING BACK TO OR A LITTLE ABOVE NORMAL. THIS RIDGE EITHER LOOKS TO GET STRETCHED OUT OR SHUNTED EAST BY FRIDAY AS ANOTHER MID/UPPER LEVEL TROUGH SLICES ACROSS NORCAL AND NORTHERN NEVADA. EITHER WAY, THERE DOES NOT LOOK TO BE ANY GREAT SIGN FOR MONSOON MOISTURE TO MAKE A RETURN BACK ON IN, SO THE FORECAST REMAINS DRY. TEMPS WERE A BLEND OF BIAS CORRECTED CONS MODELS WITH A LITTLE ECMWF AND MEX MOS MIXED ON IN. && .AVIATION...FOR MCCARRAN...PREVAILING WIND DIRECTION WILL BE FROM THE SOUTH THROUGH THE MORNING. DRIER AIR ARRIVES TODAY ALTHOUGH SOUTHWEST WINDS WILL INCREASE WITH GUSTS UP TO 25 KTS POSSIBLE. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...A DRY SOUTHWEST FLOW WILL START TO SPREAD ACROSS MOST OF THE REGION TODAY WITH ANY THREAT OF THUNDERSTORMS CONFINED TO THE HIGHER TERRAIN OF MOHAVE COUNTY. SKIES WILL BE MOSTLY CLEAR ELSEWHERE. SOUTHWEST WINDS GUSTING AROUND 30 KNOTS THIS AFTERNOON IN THE WESTERN MOJAVE DESERT AND SOUTHERN GREAT BASIN. && .SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. && $$ PIERCE/STACHELSKI FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
405 AM CDT FRI AUG 22 2014 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 403 AM CDT FRI AUG 22 2014 WITH THE UPPER AIR PATTERN, THE GFS AND ECMWF WERE SIMILAR AND FASTER THAN THE NAM AND THE GEM. NAM WAS THE SLOWEST MODEL. AT THE SURFACE, THE ECMWF WAS THE SLOWEST SOLUTION OF THE SET. WILL PREFER THE ECMWF. WATER VAPOR LOOP INDICATED A SHORT WAVE TROUGH OVER THE MT/ND BORDER. SHORT WAVE TROUGH FORECAST TO MOVE INTO SOUTHERN MAN THIS AFTERNOON. WILL HAVE SCATTERED PRECIP OVER THE NORTHERN ZONES FOR TODAY. ALSO WATER VAPOR LOOP INDICATED UPPER LEVEL LOW OVER THE PACIFIC NORTHWEST IS FORECAST TO AMPLIFY TODAY, THEN WEAKENS A BIT. TROUGH MOVES OUT OF THE ROCKIES AND TAKES ON A NEGATIVE TILT AND INTENSIFIES AGAIN AFTER 72 HOURS. ALSO UPPER LEVEL LOW OVER THE DESERT SOUTHWEST WILL MOVE INTO THE NORTHERN PLAINS SAT/SAT NIGHT/SUN AND PRODUCE ANOTHER ROUND OF PRECIP. 700 THETA-E RIDGE ALSO MOVES OVER THE AREA. PRECIPITABLE WATER RISES TO TO OVER 2 INCHES BY SAT. WILL ADD THREAT OF HEAVY RAIN FOR SAT AFTERNOON AND SAT NIGHT. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 403 AM CDT FRI AUG 22 2014 /MON THROUGH FRI/ THE LONG RANGE MODELS ARE SOMEWHAT IN AGREEMENT FOR NEXT WEEK WITH A CHANGING UPPER LEVEL PATTERN...HOWEVER THE GFS IS FASTER WITH A SHARP SHORT WAVE CROSSING THE NORTHERN PLAINS MID WEEK. IT IS ALSO MUCH DRIER WITH THE ECMWF KEEPING PRECIP ACROSS THE SOUTHEASTERN CWA. DRY POPS FOR THE MAJORITY OF THE CWA (MOST OF ND AND NW MN) ON MON/TUE SEEM REASONABLE WITH UPPER PATTERN KEEPING BEST ENERGY FROM CENTRAL PLAINS INTO THE GREAT LAKES. BY WED/THU THE GFS BUILDS A RIDGE OVER SASKATCHEWAN WHILE THE ECMWF IS A BIT FURTHER WEST WITH THE RIDGE AXIS AND ALSO LESS AMPLIFIED. DAY SIX SHOWING SOME LIGHT PRECIP OVER AREA WITH THE NW FLOW PATTERN BECOMING DRY AT NIGHT...WHICH SEEMS REASONABLE FOR NW UPPER FLOW PATTERN. FOR LATE IN THE WEEK THE GFS CONTINUES TO AMPLIFY THE UPPER RIDGE OVER THE NORTHERN TIER AND MB...KEEPING THINGS DRY...WHILE THE ECMWF HAS MORE ZONAL FLOW WITH WAVES MOVING ACROSS SRN CANADA. WILL LOWER INHERITED CHANCE POPS FOR THE END OF THE WEEK. SIGNIFICANT DIFFERENCE IN MODEL SOLUTION BEGIN ON FRI...WITH THE GFS SHOWING A STRONG LOW BRINGING PRECIP TO THE AREA AND THE ECMWF CONTINUES THE ZONAL FLOW PATTERN...GIVING ME VERY LOW CONFIDENCE IN SOLUTION FOR DAY 7. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1135 PM CDT THU AUG 21 2014 THE HRRR INDICATES A FAIRLY STRONG SIGNAL FOR IFR/LIFR CONDITIONS DEVELOPING OVERNIGHT. THEREFORE...GIVEN THE HIGH SFC MOISTURE WILL TAKE CIGS DOWN INTO THE IFR CATEGORY FOR ALL SITES OVERNIGHT. LOW CIGS AND FOG COULD LINGER WELL INTO FRI MORNING/EARLY AFTERNOON WITH PLENTY OF LOW LEVEL MOISTURE...BUT WILL ATTEMPT TO IMPROVE CONDITIONS INTO MVFR CATEGORY BY AFTERNOON. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...HOPPES LONG TERM...SPEICHER AVIATION...DK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1136 PM CDT THU AUG 21 2014 .UPDATE... ISSUED AT 1135 PM CDT THU AUG 21 2014 WE ARE STILL GETTING SOME SHOWERS MAINLY IN THE NORTH WHERE LINGERING INSTABILITY NEAR THE SFC BOUNDARY PERSISTS. THIS CONVECTION COULD LINGER THROUGH THE NIGHT...AND WITH A SHORTWAVE MOVING INTO THE NORTH LATE TONIGHT...WILL MENTION SOME LOW POPS FOR SHOWERS THROUGH THE NIGHT. OTHERWISE...NO CHANGE FROM PREVIOUS UPDATE. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 320 PM CDT THU AUG 21 2014 THE MAIN FORECAST CHALLENGE CONCERNS PCPN CHANCES AND TEMPERATURES. NAM/RUC INITIALIZED BEST HOWEVER NAM LOOKS TO BE THE ODD MODEL OUT IN LATER PERIODS AND DISCARDED. OPERATIONAL MODELS CONTINUE TO OVER FORECAST PCPN ACROSS THE REGION SIGNIFICANTLY. ABOUT THE ONLY THING MODELS AGREE ON IS THAT THE REGION WILL PERSIST IN SW FLOW ALOFT THROUGH THE PERIOD. FOR TONIGHT SURFACE LOW ALONG ND/SD/MN BORDER AREA WILL CONTINUE TO DRIFT EAST. TRAILING SURFACE BOUNDARY WILL ROUGHLY BISECT FA FROM NW-SE. WATER VAPOR LOOP INDICATING WEAK IMPULSE MOVING INTO THE CENTRAL DAKOTAS WHICH WILL LIFT NE TONIGHT. WITH IMPULSE AND BOUNDARY WILL MAINTAIN SOME MODEST POPS THROUGH THE EVENING. ONCE THE WAVE LIFTS NE LATER TONIGHT A RIDGE OF HIGH PRESSURE NOSING IN SHOULD KEEP MOST AREAS DRY. CLOUDS MOST AREAS AT LEAST PART OF THE NIGHT AND ELEVATED DEWPOINTS WILL KEEP MINIMUMS GENERALLY IN THE 60S. WEAK SURFACE HIGH PRESSURE WILL CONTINUE ACROSS THE FA ON FRIDAY/FRIDAY NIGHT. ALOFT IN SW FLOW ANOTHER WEAK WAVE WILL TO LIFT NE. POTENTIALLY THE MOST ACTIVE AREA WILL BE TO OUR WEST HOWEVER SOME PCPN MAY CLIP DVL BASIN SO WILL MAINTAIN SOME LOW POPS. REMAINDER OF THE FA SHOULD FOR THE MOST PART BE DRY. TEMPERATURES WILL HINGE ON CLOUD TRENDS SO HELD PRETTY CLOSE TO CURRENT VALUES. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 320 PM CDT THU AUG 21 2014 POOR MODEL AGREEMENT THROUGH SUNDAY AS UPPER LOW CROSSES NORTHERN ROCKIES INTO THE NORTHERN HIGH PLAINS. ALL SHOWING DIFFERENT SOLUTIONS ON TRACK/TIMING OF UPPER LOW AND ASSOCIATED SURFACE FEATURES. GENERAL THOUGHT IS THAT LOW PRESSURE WILL ORGANIZE OVER THE CENTRAL PLAINS/HIGH PLAINS AND LIFT NE THROUGH THE LATER HALF OF THE WEEKEND. WITH DIFFERING SOLUTIONS ON LOW LEVEL FEATURES TRYING FINE TUNE FAVORED LOCATIONS FOR SIGNIFICANT PCPN VERY DIFFICULT AT THIS TIME. AS A RESULT MADE MINIMAL CHANGES TO POPS IN LATER PERIODS. LITTLE CHANGE IN THERMAL PROFILES SO AGAIN TEMPERATURES WILL HINGE ON CLOUD COVER BUT LIKELY TO REMAIN BLO AVERAGE. FOR SUNDAY NIGHT THROUGH WEDNESDAY...MODELS COMING INTO BETTER AGREEMENT AT THIS POINT...BUT GFS SFC FEATURES AND PCPN BECOME THE OUTLIER. THEREFORE...A BLENDED ECMWF/GEM SOLN IS PREFERRED ATTM. OTHERWISE...SFC LOW PRESSURE DEVELOPING OVER THE UPPER MIDWEST IS EXPECTED TO LIFT TO THE NE. UPPER LEVEL TROF LOOKS TO CROSS THE AREA BRINGING COOLER AIR BEHIND THE SYSTEM...AND FRONTOGENETICAL FORCING TO TRIGGER -SHRA/-TSRA ALONG AND AHEAD OF THE LOW. SUFFICIENT LL MOISTURE AVAILABLE TO WRAP BEHIND THE SYSTEM...KEEPING SKIES MOSTLY CLOUDY. AS THE UPPER TROF DIGS IN...LOOK FOR COOLER TEMPS TO ROUND OUT THE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1135 PM CDT THU AUG 21 2014 THE HRRR INDICATES A FAIRLY STRONG SIGNAL FOR IFR/LIFR CONDITIONS DEVELOPING OVERNIGHT. THEREFORE...GIVEN THE HIGH SFC MOISTURE WILL TAKE CIGS DOWN INTO THE IFR CATEGORY FOR ALL SITES OVERNIGHT. LOW CIGS AND FOG COULD LINGER WELL INTO FRI MORNING/EARLY AFTERNOON WITH PLENTY OF LOW LEVEL MOISTURE...BUT WILL ATTEMPT TO IMPROVE CONDITIONS INTO MVFR CATEGORY BY AFTERNOON. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...DK SHORT TERM...VOELKER LONG TERM...HOPKINS/VOELKER AVIATION...DK
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
415 AM EDT FRI AUG 22 2014 .SYNOPSIS... ROUNDS OF SHOWERS AND THUNDERSTORMS CONTINUE WITH OCCASIONAL DOWNPOURS...AS WEAK DISTURBANCES RIDE SE. HIGH PRESSURE WILL TRY TO NOSE IN FROM THE NORTHEAST EARLY NEXT WEEK AS UPPER RIDGE BUILDS. && .NEAR TERM /THROUGH TONIGHT/... ENTERING INTO THE PEAK OF THE FLASH FLOOD CONCERN - NOW INTO TONIGHT. BEST LOW LEVEL INFLOW AT 925 MB IS ONGOING WITH 20 TO 30 KNOT UNDISTURBED FEED UP THE OHIO VALLEY AND INTO THE WNW TO ESE BAROCLINIC ZONE. 925 MB REDUCES TO 10 TO 15 KNOTS AFTER 18Z TODAY. SEVERAL SMALL MID LEVEL 500 MB VORT MAXIMUMS IN THE NW FLOW ALOFT. ONE PASSES CROSSES SRN WV MOUNTAINS AROUND 12Z. 07Z RAP HAS ANOTHER ALONG INDIANA/OHIO BORDER BY THEN. HOWEVER...EVEN AT 08Z...MORE STORMS HAVE REACHED INTO WESTERN OHIO. SO...DOING HOURLY POPS WAS CERTAINLY A CHALLENGE ON THIS GRAVEYARD SHIFT. EVEN THOUGH THE PKB-CKB AREA DID NOT GET MUCH RAIN ON THURSDAY...MOST COUNTIES HAVE BEEN AFFECTED PAST WEEK. DID NOT WANT TO OVER FORECAST WHERE EACH CLUSTER OF STORMS MAY GO AND TRY TO NARROW DOWN THE WATCH. POSTED A FLASH FLOOD WATCH FOR ENTIRE CWA THROUGH 05Z SATURDAY. STILL SEEMS THE HEART OF THE CWA MOST VULNERABLE. EVEN THE 07Z RAP HAS THE AXIS OF MAXIMUM PW FM NRN IL ESE INTO CENTRAL WV AOA 2 INCHES. HOWEVER...THE SOUTHERN COAL FIELDS HAVE BEEN THE WETTEST LATELY AND WOULD HAVE THE HIGHEST RUNOFF PERCENTAGE. STEERING FLOW TURNS MORE NORTH OVERNIGHT TONIGHT...SO PICTURING THE TREND WILL BE FOR THE HIGHER POPS TO SINK INTO SOUTHERN COUNTIES OVERNIGHT. THOUGH AS MENTIONED...LOW LEVEL INFLOW...AS MENTIONED...NOT AS STRONG. IN THIS PATTERN...COULD EVEN SEE STRONG RISES ON SOME HEADWATER RIVERS TONIGHT INTO SATURDAY. && .SHORT TERM /SATURDAY THROUGH MONDAY/... BOUNDARY CONTINUES SINKING SOUTH SATURDAY...BUT STILL ENOUGH MOISTURE AROUND TO KICK OFF SOME DIURNALLY DRIVEN SHOWERS AND STORMS...MAINLY IN THE COAL FIELDS AND WV MOUNTAINS. PRECIP CHANCES WILL GRADUALLY DECREASE NORTH TO SOUTH THROUGH THE WEEKEND...EVENTUALLY DRYING OUT ACROSS THE NORTH AS HEIGHTS BUILD AND A SURFACE HIGH NOSES IN FROM THE NE BY SUNDAY NIGHT. DESPITE THE BOUNDARY HEADING SOUTH...STILL EXPECTING VERY WARM TEMPERATURES. MADE ONLY MINIMAL CHANGES TO PREVIOUS HIGHS AND LOWS BY BLENDING IN BIAS-CORRECTED CONSENSUS GUIDANCE. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... UPPER RIDGE CONTINUES TO BUILD INTO AREA BUT THE OPPRESSIVE HEAT SHOULD STAY W OF THE AREA. HOWEVER...WE WILL STILL BE CONTENDING WITH THE MUGGIES WITH TEMPS RUNNING NEAR NORMAL TO PERHAPS SLIGHTLY ABOVE. A FRONT APPROACHES LONG ABOUT THURSDAY WITH INCREASING CHANCES FOR SHRA/TSRA. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... ONE ROUNDS OF CONVECTION MOVES THROUGH 06Z TO 12Z WITH LOCALIZED DOWNPOURS AND IFR VSBY AND CEILING. OTHER DISTURBANCES IN ITS WAKE WILL RIDE SE AND MAY CAUSE ADDITIONAL CLUSTERS DURING THE MORNING...FIGURING MORE IN SOUTHERN OHIO INTO WESTERN WEST VIRGINIA FOR THE 12Z TO 15Z TIME FRAME...BUT CONFIDENCE IS LOW. CEILINGS BECOMING MAINLY 2 TO 3 THSD FT BKN WITH LAYERS AND VSBY 5 TO 6 MILES IN HAZE AFTER ABOUT 16Z. YET...ADDITIONAL CLUSTERS OF SHOWERS AND STORMS LIKELY...INTO THE EVENING HOURS...AGAIN WITH IFR VSBY AND CEILINGS. MVFR VSBY LIKELY 03Z TO 06Z SATURDAY WITH SHOWERS WANING. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: DURATION AND TIMING ROUNDS OF CONVECTION WILL VARY. AT LEAST SOME AREAS OF PCPN MAY EVEN LINGER LONGER FRIDAY NIGHT...BUT NOT MENTIONED IN TAFS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE FRI 08/22/14 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY H H M M M H H M M M M M HTS CONSISTENCY L M M H H M M M M M M M BKW CONSISTENCY M M M M M M M H H H M M EKN CONSISTENCY H H M H H H H H H H H H PKB CONSISTENCY M M M M M L H H H M H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 06Z SATURDAY... IFR CONDITIONS POSSIBLE IN LOW STRATUS IN LINGERING LOW LEVEL MOISTURE 06Z TO AFTER 12Z SATURDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WVZ005>011-013>020- 024>040-046-047. OH...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OHZ066-067-075-076- 083>087. KY...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR KYZ101>103-105. VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ003-004. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...30 AVIATION...KTB
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
421 AM CDT FRI AUG 22 2014 .SHORT TERM... AFTERNOON AND EVENING THUNDERSTORM CHANCES WILL LIVE ANOTHER DAY. A CLOSED LOW CURRENTLY OVER ARIZONA WILL OPEN UP AS IT MOVES ACROSS THE ROCKIES AS A SHORT WAVE TROUGH. HOWEVER...IT REMAINS QUESTIONABLE ON WHETHER WE WILL BENEFIT FROM THIS TROUGH AS ITS JET MAX WILL BE PLACED WELL NORTH AND WEST OF THE REGION. WE STILL STILL LIKELY SEE ISOLATED TO SCATTERED CONVECTION UNDERNEATH A MONSOONAL MOISTURE PLUME CAUGHT BETWEEN THE TROUGH TO THE WEST AND RIDGE TO THE EAST. CONVENTION WILL BE WITHIN THE SURFACE PRESSURE TROUGH AND THE RAP INDICATES A FARTHER EASTWARD MOVEMENT TO THE TROUGH AXIS. LOW LEVEL CONVERGENCE MAY BE MORE TO THE EAST IF THE RAP IS MORE CORRECT IN ITS SOLUTION ALLOWING FOR CONVECTION TO DEVELOP FARTHER EAST ON THE CAPROCK. A NOTABLE DECREASE IN PRECIPITABLE WATER VALUES WILL OCCUR TODAY MOSTLY FOR AREAS EAST OF THE I27 CORRIDOR. THIS WILL BE DUE TO DRIER AIR ADVECTING INTO THE AREA AT MID LEVELS. THERE WILL NOT BE MUCH CHANGE FOR AREAS WEST OF I27 WITH CONTINUED ANOMALOUSLY HIGH PRECIPITABLE WATER VALUES. AN AXIS OF HIGHER INSTABILITY IS PROGGED TO BE AROUND 2000 J/KG WITHIN THE PRESSURE TROUGH WHERE THE HIGHEST LOW LEVEL THETA-E AIR WILL BE LOCATED. FURTHERMORE...STORM PROPAGATION VECTORS TO THE SOUTHWEST WILL LEAD TO POSSIBLE TRAINING OF CONVECTION AND REPEATED HEAVY RAINFALL DESPITE RELATIVELY HIGH CLOUD BASES. && .LONG TERM... A THINNING BAND OF MONSOONAL MOISTURE WILL CONTINUE ACROSS THE AREA OVER THE WEEKEND AS AN UPPER TROUGH SKIRTS BY TO THE NORTH. LIMITED IF ANY SIGNIFICANT LIFT IS EXPECTED THOUGH MODEST SURFACE TROUGHING AND STRONG HEATING MAY CONTRIBUTE TO A FEW AFTERNOON STORMS IN AND NEAR THAT TROUGH. HEIGHTS WILL REBUILD EARLY NEXT WEEK WITH THE MONSOON FLOW IMPROVING AGAIN...THOUGH SHIFTING BACK TO THE WEST. UNCLEAR JUST YET IF THIS WILL REMAIN NEAR ENOUGH OUR WESTERN BORDER AREAS FOR MENTIONABLE THUNDER CHANCES. UNCERTAINTY INCREASES THE MIDDLE OF NEXT WEEK INVOLVING THE NEXT PROGRESSIVE PACIFIC TROUGH CROSSING THE NORTHERN TIER. BOTH AMPLITUDE AND TIMING ARE MUCH IN QUESTION...THUS PRECLUDING THUNDER MENTION AS WELL FOR NOW. BUT THIS MAY YET REPRESENT OUR NEXT REAL OPPORTUNITY FOR THUNDERSTORMS AS A FRONTAL BOUNDARY THAT HAS BEEN HANGING ACROSS NORTHERN STATES COULD SAG INTO OUR AREA. IN THE DAYS AHEAD WE WILL WATCH FOR THOSE TIMING AND STRENGTH ISSUES TO BECOME BETTER RESOLVED. RMCQUEEN && .PRELIMINARY POINT TEMPS/POPS... FRIONA 92 64 93 62 92 / 30 40 20 20 20 TULIA 94 65 95 65 93 / 20 20 20 20 20 PLAINVIEW 93 65 94 65 92 / 20 20 20 20 20 LEVELLAND 94 64 93 64 92 / 20 20 20 20 20 LUBBOCK 95 67 96 67 94 / 20 20 20 20 20 DENVER CITY 94 65 94 65 93 / 20 20 10 10 10 BROWNFIELD 95 65 95 66 94 / 20 20 10 10 10 CHILDRESS 100 70 100 72 99 / 10 10 10 10 10 SPUR 97 68 97 67 96 / 10 10 10 10 10 ASPERMONT 99 71 100 71 99 / 0 0 10 10 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 01/05 Area Forecast Discussion National Weather Service Spokane WA 232 AM PDT FRI AUG 22 2014 .SYNOPSIS... Friday will bring another round of showers and thunderstorms to the region with the potential for more flash flooding over the Cascades burn scars. The threat of scattered showers and thunderstorms will continue through the weekend. A drier and warmer weather pattern is expected for the new work week. && .DISCUSSION... Friday: A deep upper-level low pressure system will pass through the region today delivering widely scattered showers and thunderstorms. Storms containing heavy rainfall and very little movement will be the main concern as the risk for flash flooding and debris flows remains elevated over the East Slopes and Okanogan Highlands. Additional urban and rural areas could also experience localized flooding impacts if a storm was to setup overhead. An isolated stronger storm could also bring brief hail and gusty outflow winds on the order of 40 mph. 2AM satellite reveals the center of the low crossing over the Columbia Gorge near the Dalles. The low will shift east toward the Tri Cities this morning...then continue toward the OR/WA/ID border by midday before tracking into SE Idaho this evening. With the low overhead, an unstable air mass will be in place with 500mb temperatures cooling near -17C. Meanwhile, a tongue of richer moisture and instability...marked well by the 850-700mb theta-e progs will wrap around the eastern and northern periphery of the low...wrapping back south on its western edge. This richer moisture in conjunction with little to no steering flow is a good recipe for storms containing heavy rainfall. The good news is that this lack of steering flow (storm movement) only resides through late afternoon then as the system departs the east, increasing northerly flow will give any lingering storms a push. Needless to say, we saw what these storms are capable of Thursday afternoon with numerous debris flows and mudslides within the Carlton Complex burn scar. As of 2AM...thunderstorms continue to go strong across the northern mountains with additional development now over the lower ID Panhandle. This activity is tied to the placement of the higher theta-E axis and lift along the northeastern periphery of the upper low dropping into the Pac NW. HRRR and local Hi-Res model simulated radar suggest the larger area of showers/storms over Ferry County will pivot to the west this morning, fall apart after sunrise, allowing cells to redevelop after a few hours of sunshine. Convective temperatures are only in the upper 60`s to lower 70`s so it won`t take much. Whether the cloud cover from this activity completely falls apart or just thins will be a major challenge related to storm intensity this afternoon. For NE WA and the ID panhandle, looks as if isolated storms will be possible through morning then afternoon heating and a few vorticity maximums will promote widely scattered storms again after the 12PM-3PM timeframe...continuing through the evening. Slightly deeper wind shear over the lower ID Panhandle could support a few organized cells capable of hail and wind gusts in excess of 40 mph but overall, the threat for severe storms (hail and damaging winds) remains low region-wide. Saturday: The upper-low will continue its march east Friday night and Saturday into Central Montana Saturday morning then North Dakota by the evening. Look for drier north to northwest flow over the Cascades and Western Basin Saturday morning to translate east into the Idaho Panhandle by Saturday evening. The main precipitation threat will concentrate over the ID Panhandle and into Western Montana. Some models are more aggressive with the drying so we may be on the high end for precipitation chances in Idaho, especially west of a line from Mullan to the Blue Mtns. Given the lingering cold pool aloft, a few convective showers will be possible in the mountains all the way to the Cascade Crest but these will be the weak and shallow variety producing little to no rainfall. We will also see breezy northerly winds as the low deepens today then pulls out Saturday. Winds will be strongest through the narrow Okanogan Valley and Purcell Trench. Winds sustained 10-20 mph with gusts to 35 mph are a strong possibility. Temperatures will remain on the cool side of normal. /sb Saturday night through Wednesday...General agreement exists between the latest medium range models with the overall field of motion. The general troffy and unsettled pattern will persist through Sunday featuring a continued threat of showers and at least isolated thunderstorms mainly during the afternoon and evening hours and concentrated over the northern mountains...with a few showers persisting well into the night over the Idaho Panhandle. Temperatures in this polar influenced air mass will run at or slightly below normal through Monday. Monday appears to bring a transition from a general trough to a new ridging cycle...with only a few lingering showers over the northeast and panhandle while the remainder of the forecast area dries out and stabilizes under the ridge driven warming aloft. Tuesday through Wednesday bring high confidence of dry and clear/partly cloudy conditions throughout the region as the polar storm track retreats to the north with temperatures once again cresting well above normal. /Fugazzi Wednesday Evening through Thursday Night: Starting Wednesday evening the strength of the ridge will be on the decline as the next trough of low pressure approaches the region. Models are still wavering a bit on the breakdown, but one thing in common for now is Wednesday will be the warmest day of the forecast period. Considering model differences for the breakdown, the GFS continues to be much more aggressive bringing a deep trough swinging through late Thursday. This solution would support another round of widespread rain as the system would have both mid latitude Pacific moisture as well as topical moisture from decaying Tropical Storm Lowell to work with. The euro on the other hand keeps the trough further north leading to a much drier zonal flow pattern for the Pac NW. Either way, we are looking at breezy to windy conditions for the later part of the week as cold air advection coupled with a tightened pressure gradient increases the winds. Both models have been fairly consistent in their respective solutions, so the DGEX was used to help lean in one models favor. It more closely followed the Euro leading to higher confidence in it. So leaning towards the euro, it delays the major threat of precip beyond the reaches of this forecast so POPs were kept relatively low. Temperatures were also raised a bit Thursday to show the transition to a more zonal pattern rather than the cold incoming trough from the GFS. One thing to keep in mind is that when models try to ingest this tropical storm moisture, it often leads to some inconsistent runs. Knowing this, the extended will need to be tinkered with throughout the next couple of days as models align better. /Fliehman && .AVIATION... 06Z TAFS: A SOMEWHAT MOIST AND UNSTABLE AIR MASS ASSOCIATED WITH AN AREA OF LOW PRESSURE WILL CONTINUE TO INFLUENCE THE AVIATION AREA FOR THE NEXT 24 HOURS. DURING THE DAYTIME HOURS SURFACE BASED CONVECTIVE SHOWERS AND THUNDERSTORMS WILL OCCUR, PRIMARILY OVER AND NEAR MOUNTAIN LOCATIONS BUT MOST TAF LOCATIONS WILL BE UNDER THREAT FOR A CLOSE MISS OR BRIEF THUNDERSTORM FRIDAY AFTERNOON AND EVENING. /MJF && .PRELIMINARY POINT TEMPS/POPS... Spokane 75 55 75 54 79 56 / 40 40 10 10 20 30 Coeur d`Alene 73 54 73 51 77 53 / 50 50 10 10 20 30 Pullman 75 51 74 49 79 51 / 40 50 20 20 20 20 Lewiston 80 60 79 56 85 59 / 60 50 30 20 10 20 Colville 72 51 78 49 81 52 / 60 50 10 10 20 30 Sandpoint 69 50 71 46 75 49 / 70 50 10 20 20 30 Kellogg 68 52 67 47 72 53 / 70 60 40 20 30 30 Moses Lake 81 58 83 56 86 58 / 30 50 10 0 10 10 Wenatchee 80 63 82 58 84 64 / 40 50 10 10 20 10 Omak 79 59 82 53 85 58 / 50 40 10 10 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flash Flood Watch through this evening for East Slopes Northern Cascades-Okanogan Valley-Wenatchee Area. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1149 PM CDT THU AUG 21 2014 .UPDATE... ISSUED AT 908 PM CDT THU AUG 21 2014 THE MAIN FOCUS FOR THE OVERNIGHT HOURS IS WITH CONVECTIVE TRENDS AND THE POTENTIAL FOR WIDESPREAD FOG. SO FAR THIS EVENING...THE MAIN CONVECTION HAS BEEN TIED TO A NARROW CORRIDOR ALONG AND AHEAD OF A SURFACE COLD FRONT/LOW THAT RUNS FROM NORTHWEST WISCONSIN THROUGH SOUTH CENTRAL MINNESOTA. 22.01Z RAP ANALYSIS SHOWS THAT SBCAPE IS ON THE WANE WITH THE TWO MAIN AREAS OF CONVECTION ALONG THE NORTHERN GRADIENT IN INSTABILITY...NW WI...AND THE OTHER MAIN CELLS ALONG THE HIGHEST INSTABILITY AXIS POKING INTO NW IOWA. THE MAIN CONVERGENCE WILL REMAIN WITH THIS SLOW MOVING FRONT THROUGH THE NIGHT THOUGH SURFACE/LOW LEVEL WINDS WILL BE DECREASING THROUGH THE NIGHT THUS WEAKENING THIS CONVERGENCE. WHILE SFC/ML INSTABILITY WILL BE DECREASING THROUGH THE NIGHT...0-3KM MUCAPE ACTUALLY GETS A BUMP UP PER THE 22.01Z RAP AS THE FRONT APPROACHES LATE. THERMAL PROFILES ARE FAIRLY WARM...SO IT WILL TAKE QUITE THE UPDRAFT TO GET ANY OF THE CONVECTION TO GO SEVERE WHICH DOES NOT LOOK LIKE IT WILL HAPPEN BASED ON THE WEAKENING CONVERGENCE. STILL MAY MANAGE TO SEE A FEW SHOWERS...JUST NOT EXPECTING ANYTHING THAT WOULD GET OUT OF HAND. WITH A HUMID AIR MASS IN PLACE WITH SURFACE DEW POINTS IN THE LOW 70S...FOG STILL LOOKS LIKE A POSSIBILITY OVERNIGHT. THE 21.21Z SREF IS LOCKING ONTO NORTHERN WISCONSIN WHERE IT APPEARS THAT A WEAK WARM FRONT IS LOCATED AND SOME LOCATIONS HAVE ALREADY STARTED TO DROP BELOW 1SM. WITH WINDS LIGHTENING UP AS THE LOW/FRONT APPROACHES...SOME MORE SITES COULD DEVELOP FOG OVERNIGHT IF THE SKIES CAN CLEAR OUT. HIGH LEVEL CLOUD COVER IS BLOWING OFF OF THE CONVECTION IN SOUTHWEST MINNESOTA AND COULD INITIALLY SLOW THINGS DOWN...BUT EXPECT THAT SKIES WILL CONTINUE TO CLEAR AND LEAD TO THIS FOG DEVELOPMENT. CONFIDENCE IS NOT HIGH ENOUGH IN THE WHEN/WHERE TO ISSUE A DENSE FOG ADVISORY...BUT SOME PORTION OF THE AREA MAY NEED ONE LATER. && .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT) ISSUED AT 340 PM CDT THU AUG 21 2014 WATER VAPOR IMAGERY SHOWING THE STRONG MID-LEVEL WAVE THAT GAVE THE AREA MAINLY MORNING SHOWERS AND THUNDERSTORMS NOW OVER EASTERN WI. SUBSIDENCE IN THE WAKE OF THIS WAVE PROVIDED SOME PARTIAL SUNSHINE TO THE ARX FORECAST AREA WITH TEMPERATURES THIS AFTERNOON IN THE MID 70S TO THE LOWER 80S. ALSO...DEW POINTS WERE CREEPING UPWARD INTO THE MIDDLE 60S TO THE LOWER 70S FOR A BIT MORE MUGGY FEEL TO THE ATMOSPHERE. MODEL CONSENSUS SHOWS WARM FRONTAL BOUNDARY REMAINING JUST TO OUR SOUTH OVERNIGHT WITH MODELS INDICATING SOME 850MB MOISTURE TRANSPORT INTO/OVER IT. THIS IS IN ADVANCE OF A WEAKER MID-LEVEL WA DETERMINISTIC MODELS LOOK BIT OVERDONE WITH QPF BASED ON THIS WEAKER SIGNAL...SO WENT WITH SMALLER-END SHOWER/THUNDER CHANCES. WITH RECENT RAINFALL AND RELATIVELY WEAK WINDS OVERNIGHT...ANY BREAKS IN THE CLOUD COULD ALSO LEAD TO SOME FOG DEVELOPMENT. FRIDAY IS LOOKING MAINLY DRY ACROSS THE AREA WITH MID-LEVEL RIDGE AMPLIFYING OVERHEAD. HOWEVER...THE BOUNDARY WILL REMAIN JUST TO OUR SOUTH BUILDING INSTABILITY THROUGH THE AFTERNOON. NO REAL TRIGGER MECHANISM TO FOCUS CONVECTION OTHER THAN WEAK CONVERGENCE ALONG THE BOUNDARY. AS SUCH...WILL GO WITH A 20-30 PERCENT CHANCE OF SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST IA/SOUTHWEST WI. OTHERWISE...PLAN ON HIGHS IN THE 80S WITH HEAT INDICES CREEPING INTO THE 95-100 DEGREE RANGE ACROSS FAR NORTHEAST IA/FAR SOUTHWEST WI. FOR FRIDAY NIGHT...LOOKING FOR THAT BOUNDARY TO OUR SOUTH LIFT NORTH AS A WARM FRONT. THIS IS IN RESPONSE TO SURFACE CYCLOGENESIS OVER THE CENTRAL PLAINS. MODELS IN GOOD AGREEMENT IN KEEPING BEST 850MB MOISTURE TRANSPORT FOCUSED MORE ACROSS WESTERN IA/MN. AS SUCH...KEPT HIGHER POPS FOCUSED MORE ACROSS NORTHEAST IA/SOUTHEAST MN...TAPERING EASTWARD OF THE MISSISSIPPI. PRECIPITABLE WATER VALUES WILL BE QUITE HIGH IN THE 1.5-2 INCH RANGE...SO ANY STORMS WILL BE CAPABLE OF SOME HEAVIER RAINFALL. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 340 PM CDT THU AUG 21 2014 LOOK FOR THE WARM FRONT TO CONTINUE TO PUSH NORTHWARD ACROSS THE AREA SATURDAY THROUGH SATURDAY NIGHT FOR ADDITIONAL SHOWER AND THUNDERSTORM CHANCES. WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR POCKETS OF HEAVIER RAINFALL GIVEN HIGHER-END PRECIPITABLE WATER VALUES. SATURDAY AFTERNOON INTO SATURDAY EVENING MAY ALSO HAVE TO BE WATCHED FOR SEVERE THUNDERSTORM POTENTIAL AS NAM INDICATING 0-3KM MUCAPE IN THE 2000-4500J/KG RANGE WITH BULK SHEAR IN THE 20-25KT RANGE. LOOKS LIKE THE HIGHEST THREAT AREA WOULD BE ALONG AND WEST OF THE MISSISSIPPI RIVER. SUNDAY LOOKING HOT/MUGGY/CAPPED AS THE AREA BECOMES ENTRENCHED IN THE WARM SECTOR OF SURFACE LOW LIFTING NORTH ACROSS THE DAKOTAS INTO CANADA. NAM DRAWING IN 27-31C 925MB AIR INTO AREAS ALONG/WEST OF THE MISSISSIPPI RIVER IN THIS WARM SECTOR WHICH WOULD DICTATE TEMPERATURES NEARING 100. TOOK A MODEL CONSENSUS FOR NOW...YIELDING HIGHS IN THE 90S. WITH DEWPOINTS IN THE 70S...RESULTING HEAT INDICES WILL BE IN THE 100-105 DEGREE RANGE FOR AREAS ALONG AND SOUTH OF I- 90. WILL KEEP AN EYE ON THIS OVER THE NEXT DAY OR TWO FOR A POSSIBLE HEAT HEADLINE. SHOWER/THUNDERSTORM CHANCES RETURN SUNDAY NIGHT INTO MONDAY AS A COLD FRONT PUSHES INTO THE AREA. THIS FRONTAL BOUNDARY LOOKS LIKE IT WILL LINGER ACROSS AREA THROUGH AT LEAST WEDNESDAY FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1149 PM CDT THU AUG 21 2014 THE MAIN FOCUS IS ON THE FOG OVERNIGHT AS MUCH OF THE CONVECTION IS STAYING WELL OFF TO THE NORTHEAST OF THE TAF SITES. WITH A HUMID AIR MASS IN PLACE AND WINDS LIGHTENING UP...SOME WIDESPREAD FOG IS EXPECTED OVERNIGHT...POSSIBLY DENSE. CONDITIONS SHOULD IMPROVE BY LATE MORNING AS TEMPERATURES JUMP UP AND CAUSE THE FOG TO MIX OUT. THE MAIN NEGATIVE FOR THE FOG IS WITH SOME MID LEVEL CLOUDS THAT ARE COMING ACROSS THE REGION FROM EARLIER CONVECTION THAT OCCURRED ALONG THE MINNESOTA/IOWA BORDER. ONCE THAT CLEARS OUT...THE FOG SHOULD DEVELOP. && .HYDROLOGY...TODAY INTO TONIGHT ISSUED AT 340 PM CDT THU AUG 21 2014 A WARM FRONT WILL LIFT NORTHWARD THROUGH THE AREA FRIDAY NIGHT THROUGH SATURDAY NIGHT AND SERVE AS A TRIGGER FOR SHOWER/THUNDERSTORM DEVELOPMENT. PRECIPITABLE WATER VALUES WILL BE IN THE 1.5 TO 2 INCH RANGE. AS SUCH...ANY STORM WILL BE CAPABLE OF HEAVY RAINFALL. NOT THINKING ANY FLOOD HEADLINES WILL BE NEEDED AT THIS TIME BUT CERTAINLY WARRANTS A WATCHFUL EYE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...DAS LONG TERM....DAS AVIATION...HALBACH HYDROLOGY....DAS
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
550 AM MST FRI AUG 22 2014 .UPDATE... UPDATED AVIATION AND FIRE WEATHER SECTIONS. && .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO MOVE THROUGH THE AREA TODAY...HOWEVER ONLY A FEW ISOLATED SHOWERS ARE EXPECTED ACROSS THE REGION. DRIER CONDITIONS ARE EXPECTED ACROSS THE AREA THROUGH THE WEEKEND ALONG WITH SLIGHTLY COOLER THAN NORMAL TEMPERATURES. A RETURN TO A MORE TYPICAL MONSOON PATTERN IS EXPECTED NEXT WEEK...WITH AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS RETURNING TO THE REGION. && .DISCUSSION... UPPER LEVEL LOW PRESSURE WAS SITUATED OVER NORTH-CENTRAL ARIZONA THIS MORNING AS OF 0830Z...WITH THE MAJORITY OF THE STORM ACTIVITY WELL AHEAD OF THE LOW IN NEW MEXICO. WHILE THERE WERE A FEW SHOWERS NOTED ON RADAR BENEATH THE UPPER LEVEL DEFORMATION ZONE /LOCATED APPROXIMATELY ALONG INTERSTATE 17/...THE STORMS FROM THURSDAY EVENING HAD LARGELY DISSIPATED ACROSS THE DESERTS. IN THE WAKE OF THIS STORM...TEMPERATURES WERE GENERALLY IN THE UPPER 60S TO LOWER 70S ACROSS THE DESERTS...APPROXIMATELY 10 DEGREES BELOW NORMAL FOR MID/LATE AUGUST. STRONG ISENTROPIC DESCENT IS EXPECTED ACROSS THE REGION TODAY AS THE TROUGH MOVES OUT OF THE AREA. BL MOISTURE WILL REMAIN SOMEWHAT ELEVATED AS 1000-700MB MEAN MIXING RATIOS WILL STILL LINGER IN THE 8-12 G/KG RANGE...HOWEVER THE LACK OF UPPER LEVEL SUPPORT SHOULD PRECLUDE MUCH IN THE WAY OF WIDESPREAD SHOWERS AND THUNDERSTORMS. GIVEN THE CLOSER PROXIMITY TO THE DEPARTING LOW...I WOULD EXPECT TO SEE A FEW POP-UP SHOWERS NORTH AND EAST OF PHOENIX WITH LITTLE OF CONSEQUENCE ACROSS THE DESERTS. THERE COULD ALSO BE SOME ACTIVITY ACROSS PORTIONS OF SOUTHEAST ARIZONA THAT GLANCES PINAL COUNTY...BUT THAT WOULD BE ABOUT IT. HI-RES WRF MODELS ALONG WITH THE HRRR PAINT A SIMILAR SOLUTION FOR TODAY. MORE SUBSTANTIAL BL DRYING IS EXPECTED THIS WEEKEND AS ALL OPERATIONAL MODELS SUGGEST MIXING RATIOS WILL DROP TO AROUND 3-4 G/KG ACROSS SOUTHEAST CALIFORNIA AND TO 6-8 G/KG ACROSS ARIZONA. WITH EVEN LESS UPPER LEVEL SUPPORT THIS WEEKEND...POPS WILL REMAIN SUBSTANTIALLY BELOW CLIMO THIS WEEKEND. NEXT WEEK WILL SEE A RETURN TO A MORE TYPICAL MONSOON SETUP AS HIGH PRESSURE SLIDES EAST AND LOW LEVEL WINDS TURN AROUND OUT OF THE SOUTHEAST. WHILE THERE ARE SOME DIFFERENCES IN THE MODELS REGARDING A TROUGH MOVING THROUGH UTAH BY THE MIDDLE OF NEXT WEEK...BOTH THE GFS AND EUROPEAN...AS WELL AS THE 12Z NAEFS INDICATE A NOTEWORTHY INCREASE IN MOISTURE ACROSS THE AREA MONDAY/TUESDAY NEXT WEEK. THIS COULD BE THE RESULT OF THE PASSAGE OF A TROPICAL SYSTEM WELL SOUTH OF THE GULF OF CALIFORNIA...OR IT COULD SIMPLY BE OUTFLOW DRIVEN FROM CONVECTION OVER SONORA. REGARDLESS...MIXING RATIOS EXPECTED TO RETURN TO THE 10-12 G/KG RANGE EARLY NEXT WEEK WHICH SHOULD SET THE STAGE FOR AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY THROUGH AT LEAST FRIDAY. TOUGH TO PICK OUT ONE ACTIVE DAY OVER ANOTHER...BUT POPS HAVE BEEN NUDGED TOWARD CLIMO /AND SLIGHTLY HIGHER EAST OF PHOENIX/ FROM TUESDAY THROUGH FRIDAY. AS FOR TEMPERATURES...THE BOUNDARY LAYER WILL STRUGGLE TO RECOVER TODAY AND TEMPERATURES SHOULD REMAIN BELOW NORMAL. SOME RECOVERY IS EXPECTED ON SATURDAY WITH A RETURN TO NORMAL TEMPERATURES EXPECTED SUNDAY THROUGH THE END OF NEXT WEEK. && .AVIATION... SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KPHX...KIWA...KSDL...KIPL..AND KBLH... A WEAKENING UPPER LOW WAS CENTERED JUST WEST OF PHX AT 12Z AND WILL CONTINUE SHIFTING EAST DURING THE DAY WITH FURTHER WEAKENING. ANTICIPATE FEW-SCT BASES AT 8-10 KFT MSL...BECOMING SCT-BKN BY MIDDAY OVER HIGHER TERRAIN NEAR AND EAST OF PHOENIX METRO. A STRAY SHOWER CANNOT BE RULED OUT OVER SOUTH-CENTRAL ARIZONA INCLUDING PHOENIX AREA...MORE LIKELY FURTHER EAST...BUT PROBABILITY TOO LOW TO REFLECT IN TAFS. EXPECT CLEAR SKIES THIS EVENING AS THE SYSTEM SHIFTS INTO NEW MEXICO AND WEAKENS EVEN FURTHER. SURFACE WINDS OVER PHOENIX AREA WILL FAVOR EAST AND SOUTHEAST DIRECTIONS THIS MORNING BEFORE TRANSITIONING TO WESTERLY AROUND MIDDAY. SURFACE WINDS OVER SOUTHWEST AZ AND SOUTHEAST CA WILL HOLD ON TO SOUTHERLY COMPONENT LONGER BEFORE TRENDING TOWARD SOUTHWEST AND WEST THIS EVENING...LOCAL GUSTS TO 20 KTS THIS EVENING IMPERIAL VALLEY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... HUMIDITIES WILL TREND UPWARD MONDAY AND TUESDAY BEFORE STARTING TO TREND DOWNWARD THURSDAY. OVERNIGHT RECOVERY WILL REMAIN GOOD THROUGH THE WEEK. STORM CHANCES WILL REMAIN SLIGHT AND FAVOR THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA HOWEVER THEY WILL EXPAND SLOWLY WESTWARD TO NEAR THE LOWER COLORADO RIVER VALLEY BY WEDNESDAY. HAINES INDEX VALUES PEAK AT 5 OVER PORTIONS OF SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA SUNDAY AND MONDAY BEFORE TRENDING DOWNWARD. EXPECT LOWER VALUES OVER SOUTH-CENTRAL ARIZONA DUE TO BETTER ATMOSPHERIC MOISTURE CONTENT. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS AVIATION...AJ FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS PUEBLO CO
502 AM MDT FRI AUG 22 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 450 AM MDT FRI AUG 22 2014 ...POTENT STORM SYSTEM TO WILL BRING FAST MOVING THUNDERSTORMS CAPABLE OF LOCALLY HEAVY RAINFALL...SMALL HAIL...AND LIGHTNING TO SOUTH CENTRAL AND SOUTHEAST COLORADO...WITH POTENTIAL FOR SEVERE WEATHER FOR NORTHERN PORTIONS OF THE SOUTHEAST PLAINS BY AFTERNOON... UPPER LOW OVER WESTERN AZ IS FORECAST TO EJECT TO THE NORTHEAST TODAY...AS THE KICKER SYSTEM DROPS THROUGH THE PACIFIC NORTHWEST. ALREADY HAVE A ROUND OF THUNDERSTORMS ONGOING ACROSS EAST CENTRAL AND NORTHEAST COLORADO ALONG/NORTH OF THE FRONT AS THE FIRST UPPER JET LIFTS OFF TO THE NORTHEAST. THESE WILL CONTINUE TO LIFT OFF TO THE NORTHEAST THIS MORNING...AND FOCUS FOR PRECIPITATION WILL TO SHIFT INTO WESTERN PORTIONS OF THE FORECAST AREA THIS MORNING AS MOISTURE AND LIFT INCREASES WITH THE NEXT IMPULSE AHEAD OF THE ADVANCING SYSTEM. SO FAR...RAINFALL RATES OUT WEST DO NOT LOOK HEAVY ENOUGH TO CAUSE CONCERNS FOR THE WEST FORK BURN SCAR...BUT THIS WILL HAVE TO BE MONITORED CLOSELY THROUGH THE MORNING. OF GREATER CONCERN WILL BE POTENTIAL FOR THUNDERSTORMS ACROSS THE SOUTHEAST MOUNTAINS THIS AFTERNOON AS UPPER TROF LIFTS ACROSS THE AREA DURING PEAK HEATING PERIOD. SFC LOW ACROSS SOUTHERN CO IS PROGGED TO LIFT BACK NORTHWARD DURING THE AFTERNOON...WITH FRONTAL BOUNDARY BECOMING THE FOCUS FOR STRONG TO EVEN SEVERE THUNDERSTORMS THIS AFTERNOON AS IT LIFTS BACK NORTHWARD. VARIOUS SHORT RANGE MODELS SHOW THIS LIFTING BACK NORTHWARD TO ALONG A LINE FROM COLORADO SPRINGS TO EADS AS OF 21Z. DEPENDING ON SFC DEW POINTS...CAPES COULD BE RUNNING ANYWHERE FROM 1000 J/KG TO 1500 J/KG TO THE NORTH OF THIS BOUNDARY...AND WITH NEXT UPPER JET SHIFTING NORTHWARD INTO THE REGION...COULD SEE DEEP LAYER SHEARS 40KTS...ESP WHERE LOW LEVEL SFC WINDS REMAIN EASTERLY. SEEMS BEST THREAT AREA FOR SEVERE POTENTIAL WILL BE ACROSS NORTHEAST EL PASO AND KIOWA COUNTIES...AND POINTS TO THE NORTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY STORM THREATS. WITH UPPER LEVEL FORCING MOVING ACROSS DURING THE AFTERNOON...HIGH RES AND CONCEPTUAL MODELS SUGGEST A LINE OF THUNDERSTORMS WILL DEVELOP ACROSS THE SOUTHEAST MOUNTAINS AND MOVE OFF TO THE NORTHEAST THROUGH THE AFTERNOON AND EARLY EVENING. LOCALLY HEAVY RAINFALL...SMALL HAIL...AND ERRATIC GUSTY WINDS UP TO 50 MPH WILL BE THE MAIN STORM THREATS. QUESTION IS...WILL THUNDERSTORMS BE CAPABLE OF PRODUCING ENOUGH RAINFALL TO CAUSE FLASH FLOODING ON AREA BURN SCARS. STORM MOTIONS TODAY WILL BE NORTH TO NORTHEAST AT AROUND 30- 35 MPH...WHICH SHOULD MITIGATE THIS THREAT SOME. HOWEVER THE WALDO BURN SCAR WITH ITS VERY LOW FLASH FLOOD THRESHOLD LOOKS TO MOST UNDER THE THREAT TODAY. IF SUFFICIENT HEATING CAN TAKE PLACE...WE COULD SEE CAPES OF NEAR 1000 J/KG (WITH SFC DEW POINTS IN THE LOWER 50S). IF FRONTAL BOUNDARY LIFTS BACK NORTHWARD INTO THIS REGION AND STALLS...THEN THIS COULD ALSO PROVIDE A FOCUS FOR A COUPLE OF ROUNDS OF THUNDERSTORMS. HOWEVER...MODELS ARE NOT ALL IN AGREEMENT OF WHERE THE HEAVIER PRECIPITATION WILL FALL. 06Z NAM12 IS THE HEAVIEST HANDED WITH QPF AMOUNTS OF OVER AN INCH FALLING ACROSS NORTHERN EL PASO AND TELLER COUNTIES DURING THE NOON TO 6 PM TIME FRAME. HOWEVER RAP13...GFS...AND ECMWF ALL KEEP PRECIPITATION AMOUNTS MUCH LIGHTER AROUND .25 TO CLOSE TO .50...AND ALL MODELS SEEM TO POINT AT THE QPF MAXIMUM OCCURRING ACROSS NORTHEAST COLORADO GIVEN THE CURRENT STORM TRACK. STILL CONTEMPLATING ISSUING A FLASH FLOOD WATCH FOR WALDO BURN SCAR TODAY. SOME FACTORS THAT FAVOR FLASH FLOODING TODAY FOR THE WALDO WOULD BE HIGHER PRECIPITABLE WATERS...GOOD FORCING WITH SHORTWAVE MOVING ACROSS DURING THE AFTERNOON...SOME POTENTIAL INSTABILITY IN THE AFTERNOON...AND EVEN A BRIEF PERIOD OF SOUTHEAST UPSLOPE BEFORE 00Z. SOME FACTORS THAT DO NOT PARTICULARLY FAVOR FLASH FLOOD POTENTIAL FOR WALDO INCLUDE FAST STORM MOTIONS...EXTENSIVE MORNING CLOUD COVER...WARMING H5 TEMPERATURES AHEAD OF THE UPPER LOW TODAY...AND QUICK SHIFT TO A SOUTHWEST DOWNSLOPE FLOW BY 00Z AS SYSTEM LIFTS TO THE NORTHEAST OF THE AREA. WOULD LIKE TO SEE A FEW RUNS OF THE HRRR RESOLVE SOME OF THESE MESOSCALE DETAILS BEFORE COMMITTING TO A WATCH. AM CONFIDENT THAT SOMEWHERE CLOSE BY...LIKELY TO THE NORTHEAST OF THE BURN SCAR...QPF AMOUNTS OF AN INCH OR MORE WILL BE POSSIBLE WITH THE STRONGER STORMS. BUT NOT CONFIDENT ENOUGH THAT THIS WILL HAPPEN ON WALDO TO GO WITH A WATCH. WILL CONTINUE TO MONITOR LATEST HIGH RES MODELS THROUGH THE MORNING AND MAY HOIST A WATCH AS DETAILS BECOME BETTER RESOLVED. REGARDLESS...ANYONE IN OR NEAR THE BURN SCARS TODAY NEEDS TO MAINTAIN A HEIGHTENED AWARENESS OF THE WEATHER TODAY. TIMEFRAME WITH THE GREATEST THREAT APPEARS TO BE BETWEEN NOON AND 6 PM. THUNDERSTORMS WILL DIMINISH RAPIDLY THIS EVENING AS THE SYSTEM LIFTS OFF TO THE NORTHEAST. SOME SHOWERS MAY LINGER ALONG THE CONTINENTAL DIVIDE PAST MIDNIGHT AS THE NEXT UPPER TROF DROPS IN FROM THE NORTHWEST. -KT .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 450 AM MDT FRI AUG 22 2014 PRIMARY LONGER TERM METEOROLOGICAL CHALLENGES INCLUDE POPS...TEMPERATURES AND EVEN SOME GUSTY WINDS AT TIMES. LATEST COMPUTER SIMULATIONS AND FORECAST MODEL SOUNDINGS SUGGEST THAT ADEQUATE ATMOSPHERIC MOISTURE WILL INTERACT WITH SEVERAL UPPER DISTURBANCES INTO THE MIDDLE PORTION OF NEXT WEEK. IN ADDITION...A NORTHERLY SURGE IS PROJECTED TO PUSH ACROSS EASTERN SECTIONS OF THE FORECAST DISTRICT TUESDAY NIGHT. THE COMBINATION OF THESE FEATURES IS EXPECTED TO GENERATE ISOLATED TO SCATTERED POPS AT TIMES OVER THE MAJORITY OF THE FORECAST DISTRICT FROM FRIDAY INTO NEXT WEDNESDAY(ESPECIALLY IF THE LATEST VERSION OF THE ECMWF IS CORRECT) WITH SOME DRYING THEN ANTICIPATED BY LATER NEXT WEEK. IN ADDITION...MAXIMUM AND MINIMUM TEMPERATURES ARE EXPECTED TO RUN WITHIN A CATEGORY OR SO OF LATE AUGUST CLIMATOLOGICAL AVERAGES DURING THE LONGER WHILE GUSTY GRADIENT WINDS WILL BE POSSIBLE AT TIMES(PRIMARILY OVER FAR EASTERN SECTIONS) FROM SATURDAY INTO SATURDAY NIGHT AND THEN AGAIN FROM SUNDAY NIGHT INTO TUESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 450 AM MDT FRI AUG 22 2014 OUTFLOW BOUNDARIES FROM THUNDERSTORMS TO THE NORTH WILL KEEP ERRATIC GUSTY NORTH WINDS GUSTY ACROSS THE KCOS AND KPUB TERMINALS THIS MORNING. WINDS WILL SHIFT AROUND TO THE EAST AND SOUTHEAST DURING THE AFTERNOON. WIDESPREAD SHOWERS AND THUNDERSTORMS ALONG THE CONTINENTAL DIVIDE THIS MORNING WILL SPREAD EASTWARD THROUGH THE AFTERNOON. THIS WILL BRING LOWERING CIGS TO KALS THROUGH THE LATE MORNING WITH THE POTENTIAL FOR AFTERNOON SHOWERS AND THUNDERSTORMS. A LINE OF THUNDERSTORMS WILL DEVELOP ACROSS THE SOUTHEAST MOUNTAINS AROUND 18Z...AND MOVE OFF INTO THE ADJACENT PLAINS AFFECTING THE KCOS AND KPUB TERMINALS AFTER 19-20Z. THE MAIN STORM THREATS TODAY WILL BE BRIEF MVFR TO IFR CONDITIONS WITH TSRA...SOME BRIEF SMALL HAIL...AND ERRATIC WIND GUSTS TO 45 KTS. HOWEVER...A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE...PARTICULARLY TO THE NORTH AND EAST OF A LINE EXTENDING FROM KCOS TO EADS THIS AFTERNOON WHERE LARGE HAIL AND WIND GUSTS TO 50 KTS OR BETTER WILL BE POSSIBLE. THUNDERSTORMS SHOULD LIFT OFF TO THE NORTHEAST DURING THE EARLY EVENING WITH -TSRA THREAT ENDING FOR ALL THREE TERMINALS BY 00Z-01Z. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
726 AM EDT FRI AUG 22 2014 .SYNOPSIS... THE THREAT FOR SHOWERS WILL CONTINUE...ESPECIALLY ACROSS THE WEST THROUGH TONIGHT. DRIER AND COOLER WEATHER FOLLOWS THIS WEEKEND. A WARM-UP IS POSSIBLE NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL BOUNDARY SWEEPING SOUTH OUT OF CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 725 AM UPDATE... LATEST RUNS OF THE HRRR APPEAR TO HAVE A GOOD HANDLE ON THE SHOWERS THIS MORNING...AT LEAST IN TERMS OF THE OVERALL TRENDS. AS SUCH...USED THE HRRR TO TWEAK POPS FOR THIS MORNING. ALSO TWEAKED TEMPERATURES AND DEW POINTS TO REFLECT THE LATEST OBSERVED TRENDS. PREVIOUS DISCUSSION... SHOWERS CONTINUE TO DEVELOP IN-SITU THIS MORNING ACROSS THE REGION AS THE FIRST OF A SERIES OF VORT-MAX/S MOVES THROUGH THE REGION EARLY THIS MORNING. PWATS ARE MARGINAL /AROUND TO JUST BELOW 1.5 INCHES/ WITH K-VALES IN THE W ABOUT 30-32. THEREFORE...SUSPECT THIS THREAT FOR -SHRA TO CONTINUE THROUGH THE MORNING. ESPECIALLY WERE WEAK CONVERGENT BOUNDARIES ARE ALLOWED TO FORM IN THE RELATIVELY WEAK NEAR SFC FLOW. WILL CARRY POPS THROUGH MID DAY MAINLY W OF THE WORCESTER HILLS INTO SRN NH...BUT WOULD NOT BE SURPRISED TO SEE A FEW SHOWERS MAKE IT INTO THE BOS-PVD CORRIDOR. OTHERWISE TODAY...THIS FIRST VORT MAX IS EXPECTED TO JOIN FORCES WITH CUTOFF LOW PRES STALLED IN BLOCKING FLOW ACROSS ATLANTIC CANADA...FORMING A HANGING TROF WHOSE BASE WILL REST TO THE S OF REGION. NOTE THAT AS THIS TROF DEVELOPS AND A SERIES OF WEAKER WAVES ROTATE THROUGH...HEIGHTS CONTINUE DECLINE INTO THE OVERNIGHT HOURS. OVERALL COLUMN MOISTURE DOES ACTUALLY DIMINISH THROUGH THE DAY...CLOSER TO BETWEEN 1.0-1.25 INCHES AND OVERALL INSTABILITY /INCLUDING K-VALUES/ DIMINISH THROUGH THE DAY AS WELL. GIVEN THIS...AND THE FACT THAT ANOTHER AXIS OF SFC BASED INSTABILITY REMAINS TO THE W IN NY THANKS TO WHAT IS LIKELY TO BE MORE CLEAR SKIES...AND CONTINUED MARINE INFLUENCE THANKS TO E COMPONENT TO THE FLOW SUSPECT CONVECTIVE ACTIVITY TO ONCE AGAIN FIRE MAINLY W OF NEW ENGLAND THIS AFTERNOON AND EVENING. THIS MAY ACTUALLY USURP SOME OF THE AVAILABLE MOISTURE...SO WILL ACTUALLY HIGHLIGHT DECLINING POPS THROUGH THE AFTERNOON...EXCEPT IN THE DUE TO REMNANT CONVECTION ADVECTING E. AS MENTIONED...EXPECT A LOT MORE WIDESPREAD CLOUD COVER TODAY THANKS TO MARINE INFLUENCE AND COOLING TEMPS ALOFT. THEREFORE...HIGHS MAY STRUGGLE TO MAKE IT OUT OF THE 60S IN SPOTS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT... AM NOTING SIMILAR SETUP AS THU NIGHT. ANOTHER WEAK SHORTWAVE WILL PUSH N-S ACROSS THE REGION AND PHASE WITH OFFSHORE LONGWAVE TROF CONNECTED TO CUTOFF IN ATLANTIC CANADA. TWO CONDITIONS ARE DIFFERENT HOWEVER...PWATS ARE A BIT LOWER /1.0-1.25 INCHES AS OPPOSED TO 1.5/ AND K INDEX VALUES ARE LOWER AS DRIER AIR INTRUDES THROUGH THE COLUMN FROM THE TOP DOWN. THEREFORE...SAVE FOR THE ADVECTION OF LEFTOVER CONVECTION FROM THE W...SUSPECT THAT -SHRA ARE LIKELY TO BE A BIT WEAKER AND LESS WIDESPREAD THAN THU NIGHT. HOWEVER...WILL STILL MAINTAIN AT LEAST CHANCE POPS ESPECIALLY FOR W AND NW PORTIONS OF THE FORECAST AREA. ONE OTHER ISSUE IS FOG AND/OR LOW CIGS MOVING INTO E PORTIONS OF THE FORECAST AREA. GUIDANCE CONTINUES TO NOTE AN AREA OF MOISTURE BACKING IN FROM THE GULF OF MAINE OVERNIGHT THANKS TO CONTINUED ELY COMPONENT OF THE FLOW. DO NOTE IN BUFKIT PROFILES THAT THERE IS A LAYER OF DRY AIR ABOVE THE SFC WHICH MAY NEGATE FOG DEVELOPMENT...ESPECIALLY IF STRATUS BACKS IN...LIMITING RADIATIVE PROCESSES. THEREFORE...WILL MAINLY MENTION LOW CLOUDS...BUT MAY NEED TO MONITOR FOR DRIZZLE WITH DRIER MOVING IN OVER MOISTURE POOLING IN THE LOW-MID LVLS. SHOULD SOME AREAS RADIATE...FOG REMAINS A RISK. SAT... ONE LAST PARTING SHOT FOR SHOWERS SAT AS SHORTWAVE ENERGY FORCES SOME DIGGING AND SOUTHWARD PROGRESSION OF THE OFFSHORE LONGWAVE TROF. LEFTOVER MOISTURE COMBINED WITH COOLING TEMPS ALOFT ARE LIKELY TO LEAD TO A FAIR AMOUNT OF CLOUD COVER DURING THE EARLY HALF OF THE DAY...ALONG WITH SHOWERS ESPECIALLY FROM PORTIONS OF THE MERRIMACK VALLEY E AND POINTS SE. HOWEVER...IMPROVEMENT BY THE AFTERNOON LOOKS POSSIBLE THANKS TO GRADUALLY RISING HEIGHTS FROM THE S SHIFT IN THE TROF. THIS WILL ALLOW SFC INVERTED RIDGING TO GRADUALLY REGAIN CONTROL ACROSS THE REGION TOWARD EVENING. IN FACT...DESPITE THE CLOUDY START TO THE DAY...ITS POSSIBLE MANY LOCATIONS STILL GET TO SEE THE SUNSET /EVEN IN THE E WHICH WILL LIKELY TAKE THE LONGEST TO BREAK OUT/. HIGHS REMAIN ON THE COOL SIDE OF NORMAL THANKS TO THE EARLY CLOUD COVER LIMITING DIURNAL INFLUENCE. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THIS PERIOD * UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING FRONT 21/00Z MODELS ARE IN GOOD AGREEMENT THROUGH ABOUT TUESDAY. THEN SIGNIFICANT DIFFERENCES ARISE FOR THE LATTER HALF OF NEXT WEEK... MAKING FOR A LOWER CONFIDENCE FORECAST FROM THE MIDDLE OF NEXT WEEK ONWARD. A PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN USA. THIS UPPER TROUGH IS RATHER PERSISTENT THOUGH...WITH EACH SUCCESSIVE MODEL RUN LINGERING THIS TROUGH OVER THE NORTH ATLANTIC LONGER AND LONGER. COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN QUEBEC WILL KEEP THINGS RELATIVELY DRY. STILL AGREE WITH THE PREVIOUS FORECASTER...THINKING 21/00Z GUIDANCE CONTINUES TO STRUGGLE WITH CONVECTIVE FEEDBACK INTO EARLY NEXT WEEK. AS SUCH...KEPT A DRY FORECAST ACROSS MOST OF SOUTHERN NEW ENGLAND. A HIGH PRESSURE WILL SINK SOUTH INTO EARLY NEXT WEEK...EVENTUALLY MOVING SOUTH AND EAST OF SOUTHERN NEW ENGLAND AND RETURNING US TO A MORE WESTERLY FLOW. A LOW PRESSURE IN ONTARIO MAY EVENTUALLY MOVE EAST INTO QUEBEC...SWINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE MODELS START TO DIVERGE MORE SIGNIFICANTLY. THE ECMWF LOOKS A BIT QUICKER THAN THE GFS WITH THE APPROACH OF THIS FRONT...BUT NEITHER IS AS PROGRESSIVE AS THE CANADIAN. WILL TAKE A BLENDED APPROACH WITH THE TIMING FOR NOW. GIVEN THE STRENGTH OF THE SURFACE RIDGE EXPECTED TO BE NEAR THE COAST...WOULD NOT BE OVERLY SURPRISED IF THE ULTIMATE TIMING TURNS OUT TO BE SLOWER THAN THE GFS. DEPENDING ON AVAILABLE MOISTURE...WE COULD SEE SOME SHOWERS AND THUNDERSTORMS AHEAD OF THIS FRONT. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH SATURDAY...MODERATE CONFIDENCE. TODAY INTO TONIGHT... CONDITIONS IMPROVE TO VFR MOST LOCATIONS THROUGH THE DAY... ALTHOUGH LOW VFR CIGS ARE LIKELY ESPECIALLY AREAS W OF THE WORCESTER HILLS. SHOWERS LINGER IN THIS REGION AS WELL. BY TONIGHT...SHOWERS DISSIPATE BUT THERE MAY BE MORE WIDESPREAD FOG IN THE W AND THE POSSIBILITY OF LOWER CIGS IN THE E. THEREFORE...COMPLEX OVERNIGHT SCENARIO...WHERE SOME OCCASIONAL MVFR/IFR CONDITIONS ARE POSSIBLE. SAT... CONDITIONS IMPROVE TO VFR ALL LOCATIONS EXCEPT MAYBE AREAS E OF THE WST-ORH-AFN...WHERE SOME MVFR CONDITIONS MAY LINGER INTO THE DAY IN LOW CIGS. BY AFTERNOON...LIKELY TO SEE VFR ALL LOCATIONS. KBOS TERMINAL...MODERATE CONFIDENCE. MAINLY VFR TODAY EXCEPT FOR OCCASIONAL SHOWERS AND MVFR THIS MORNING. OVERNIGHT...EASTERLY FLOW COULD YIELD A PERIOD OF LOW CLOUDS WITH MVFR/IFR CIGS POSSIBLE. SHOULD THESE BE ESTABLISHED...ITS POSSIBLE THEY LINGER INTO THE MORNING HOURS SAT. KBDL TERMINAL...MODERATE CONFIDENCE. MVFR/VFR MAY BOUNCE BACK AND FORTH THROUGH THE MORNING WITH SHOWERS. BY AFTERNOON...CONDITIONS IMPROVE TO VFR AND MAY STAY THAT WAY THEREAFTER. OUTLOOK...SATURDAY THROUGH TUESDAY... HIGH CONFIDENCE VFR. LOW PROBABILITY OF PATCHY MVFR/IFR FOG EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH SATURDAY...HIGH CONFIDENCE. E TO NE FLOW WILL CONTINUE INTO SAT AS HIGH PRES TO THE NE SLOWLY REGAINS CONTROL. THROUGH THE DAY TODAY AND NIGHT TONIGHT...PERIODS OF WIND GUSTS OF 15-20 KT ARE POSSIBLE AT TIMES WITH A SLOWLY BUILDING SWELL. SEAS SHOULD REMAIN BELOW 4 FT EVEN ON THE SE AND S WATERS. THEREFORE...NO SMALL CRAFT HEADLINES. SOME FOG AND SHOWERS ARE POSSIBLE ON THE WATERS AT TIMES AS WELL...MAINLY THIS MORNING...AND ONCE AGAIN OVERNIGHT. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... HIGH CONFIDENCE. HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED FOR MUCH OF THIS PERIOD WITH HIGH PRESSURE ACROSS THE REGION. SEAS COULD APPROACH 5 FT ACROSS THE OUTERMOST SOUTHERN COASTAL WATERS THIS WEEKEND. NOT ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY THOUGH. LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES. && .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 COLUMBIA SC
1016 AM EDT FRI AUG 22 2014 .SYNOPSIS... A STRONG UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS TODAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... THIN HIGH CLOUDS ACROSS THE MIDLANDS LATE THIS MORNING. TEMPERATURES IN THE MID/UPPER 80S WELL ON THE WAY TO AROUND 100 DEGREES FOR LATER THIS AFTERNOON. MODELS INDICATE SUBSIDENCE THROUGH LATE AFTERNOON. HAVE DELAYED CHANCE FOR CONVECTION UNTIL 21Z BASED TIMING OF SHORT WAVE INDICATED BY THE RUC AND NAM MODELS AND ALSO BASES ON HI RES MODELS. OTHERWISE FORECAST STILL ON TRACK. PREVIOUS DISCUSSION: UPPER LEVEL RIDGE REMAINS CENTERED OVER THE LOWER MISSISSIPPI VALLEY. SURFACE TROUGH ACROSS COASTAL CAROLINA. LOW LEVEL DOWNSLOPE FLOW WILL CONTINUE TODAY. BOUNDARY LAYER AND 850MB TEMPERATURES SUPPORT AFTERNOON TEMPERATURES NEAR 100 DEGREES. DEW POINTS MIXING DOWN INTO THE 60S WILL RESULT IN HEAT INDEX VALUES AROUND 105. NAM MODEL SUGGEST STRONGER INSTABILITY THAN GFS. BUT EXPECT HIGH LFC AND LIMITED LIFT FOR THUNDERSTORMS. BULK OF CONVECTION EXPECTED NORTH OF THE REGION AROUND UPPER LEVEL RIDGE. ISOLATED THUNDERSTORMS FORECAST THIS AFTERNOON AND EARLY EVENING. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. THIN CIRRUS CLOUDS ACROSS THE TAF SITES IN NORTHWEST FLOW ALOFT. DIURNAL CUMULUS EXPECTED TO DEVELOP THIS AFTERNOON. GIVEN FRONTAL BOUNDARY REMAINING WELL NORTH OF THE AREA...CHANCE FOR CONVECTION TOO LOW TO INCLUDE IN TAFS ATTM. WINDS THROUGH THE PERIOD WILL BE WESTERLY AT 7 KNOTS OR LESS. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1038 AM CDT Fri Aug 22 2014 .UPDATE... ISSUED AT 1038 AM CDT FRI AUG 22 2014 Large cluster of thunderstorms that developed along an outflow boundary late last night continues to diminish as it pushes eastward across central Illinois this morning. 1530z radar imagery shows showers with a few embedded thunderstorms along/north of a Beardstown...to Decatur...to Paris line. High-res models suggest a continued weakening trend, with little or no precip remaining by mid-afternoon. Have adjusted PoPs to go categorical along/north of I-72 for the next couple of hours, followed by a decrease to just slight chance this afternoon. Have also lowered high temperatures by a few degrees across the central and northern zones where widespread clouds/rain have kept readings cooler than previously expected. Visible satellite imagery shows plenty of breaks developing upstream across Iowa, so have only dropped highs into the upper 80s. Further south where the rain has not occurred this morning, have maintained highs in the lower 90s. && .SHORT TERM...(Today and tonight) ISSUED AT 325 AM CDT FRI AUG 22 2014 07z/2am surface analysis shows a stationary front extending from west to east across northern Illinois. A 35kt LLJ has helped trigger a line of convection just south of that front. Those storms will affect our northern counties early this morning, with locally heavy rainfall rates possible. Areas near Midway airport last night picked up 3" in 30 minutes. There most likely will be a break in the rainfall for at least a few hours later this morning and early this afternoon, before the next shortwave over Iowa works its way into IL. Precipitable water values up near 2" will continue through the day, so any convection that redevelops this afternoon into evening will have the potential to produce very heavy rainfall. Coverage may not be too extensive during the day, so slight chance and low chance PoPs were used for areas north of I-72 after 7 am. The HRRR/NAM/GFS/ECMWF all show an enhanced opportunity for storms either later this afternoon or this evening as an MCS develops to our west and rolls across N IL. With timing still in question, we did not ramp up to likely PoPs in any one area even this evening and overnight. The main theme does seem to be that the northern half of the KILX CWA will be the main target area for storms over the next 24-36 hours. High temps today will once again climb into the upper 80s to low 90s, with dewpoints already in the mid 70s and likely to climb into the upper 70s in some areas. Heat index readings will likely climb to around 105 in southern areas. We can not rule out the possible need to expand the heat advisory northward. Precip and cloud cover across the north should keep their heat index readings below advisory levels in general. && .LONG TERM...(Saturday through Thursday) ISSUED AT 325 AM CDT FRI AUG 22 2014 Main issue through the extended remains the extreme heat for this time of year through the weekend and into the first portion of next week. Models still having issues with the ultimate breaking down of the ridge, resulting in a potential extension to the heat wave should the trend continue. Hot daytime highs into the 90s and dewpoints into the mid 70s resulting in heat indices over 100F for several days on end. Scattered chances exist as long as the boundary remains close to the FA...and will be the only chance for brief cool downs. But as the high builds into the region, the general subsidence will be hard to overcome, so the forecast for Saturday night through Sunday night is dry for now...with some slight chances coming back for Monday...but the models struggling with the solutions in the mid range with the timing of a vigorous wave to erode the ridge. GFS still far more aggressive, amplified, and fast with the passage of the upper trof/sfc front Tues night into Wednesday. ECMWF starting to close the gap and has abandoned the closed low of 24 hrs ago... but is still signif weaker, resulting in a developing baroclinic zone at the sfc as the wave fizzles in parallel flow and provides a focus for a longer duration potential for precip. Model blends now through the mid/end of next week results in more widespread chances. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 652 AM CDT FRI AUG 22 2014 A nocturnal LLJ has helped fuel an east-west line of storms across north-central IL. The storms with heavy rainfall will affect mainly PIA, BMI and CMI early this morning, bringing MVFR vis and ceilings. BMI has dropped to IFR cloud height, which could linger through 15z before lifting to MVFR. A break in the storms is indicated for the terminal sites for late morning into afternoon in the HRRR and RAP model output. Additional storm chances are indicated for later this afternoon and evening for the northern TAF sites of PIA, BMI and CMI. We kept precip our of DEC and SPI for now, but trends are for storms to get quite close even this morning. Will monitor closely for changes to the dry forecast for SPI/DEC. Winds will generally remain S-SW in the synoptic flow across our area, south of the warm front. Local northerly winds have developed for the northern terminals where the storms have produced an outflow boundary moving south. The outflow could even reach SPI and DEC, but wind speeds by then should be 10kt or less. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. && $$ UPDATE...BARNES SHORT TERM...SHIMON LONG TERM...HJS AVIATION...SHIMON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
654 AM CDT FRI AUG 22 2014 .DISCUSSION... 349 AM...FORECAST CONCERNS INCLUDE HEAVY RAIN WITH THUNDERSTORMS THROUGH SATURDAY NIGHT...IN ADDITION TO TIMING AND LOCATION OF STORMS. ADDITIONAL CONCERNS AND CHALLENGES INCLUDE TEMPERATURES/ DEWPOINTS AND ASSOCIATED HEAT INDICES THROUGH EARLY NEXT WEEK. ONE COMPLEX OF THUNDERSTORMS MOVING ACROSS FAR NORTHEAST IL AND NORTHWEST INDIANA WITH A SECOND COMPLEX MOVING SOUTHEAST ACROSS THE SOUTHERN CWA. THESE ARE VERY EFFICIENT RAIN PRODUCES WITH DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES AROUND 2 INCHES. COOP OBSERVER 3SW OF MIDWAY AIRPORT MEASURED 3.60 INCHES OF RAIN IN JUST 40 MINUTES WITH SEVERAL REPORTS OF FLOODED ROADS IN THAT AREA. WHILE ADDITIONAL ACTIVITY CONTINUES ACROSS THE AREA...THE GENERAL TREND IS FOR ALL THIS ACTIVITY TO MOVE SOUTHEAST THIS MORNING. HOWEVER...ADDITIONAL ACTIVITY OVER WESTERN IL AND SOUTHERN IOWA MAY CONTINUE MOVING EAST ACROSS THE SOUTHERN CWA LATER THIS MORNING. CONVECTIVE TRENDS ARE STILL SOMEWHAT UNCERTAIN OVER THE NEXT 36 HOURS OR SO. IF CURRENT ACTIVITY ACROSS SOUTHERN IA/WESTERN IL DRIFTS SOUTHEAST...MUCH OF THE DAYLIGHT HOURS COULD END UP RATHER DRY WITH TONIGHT POSSIBLY BEING MORE ACTIVE AS HINTED AT BY THE ECMWF. HAVE TRENDED THIS DIRECTION BUT CONFIDENCE IS LOW. WITH DEWPOINTS REMAINING IN THE LOWER/MID 70S AND PRECIPITABLE WATER VALUES REMAINING AROUND 2 INCHES...ADDITIONAL TORRENTIAL RAIN WILL BE POSSIBLE WITH ANY STORMS THAT DEVELOP. IF TRENDS BECOME MORE CLEAR...ITS POSSIBLE A FLASH FLOOD WATCH MAY BE NEEDED FOR PART OF THE AREA...BUT GIVEN THE UNCERTAINTY OF WHEN/WHERE ADDITIONAL HEAVY RAIN WILL OCCUR...NO HEADLINES THIS MORNING. CONVECTION THEN APPEARS TO SHIFT NORTHEAST DURING THE DAY ON SATURDAY AS THE UPPER RIDGE BUILDS INTO THE AREA. THUS A DRY PERIOD IS EXPECTED FROM LATER SATURDAY NIGHT THROUGH SUNDAY NIGHT AND POSSIBLY INTO MUCH OF THE DAY ON MONDAY. CHANCE POPS THEN ENTER BACK INTO THE FORECAST THROUGH THURSDAY. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT WITH A COLD FRONT MOVING ACROSS THE AREA MIDWEEK...THOUGH TIMING DIFFERENCES REMAIN. ADDITIONAL HEAVY RAIN WILL BE POSSIBLE DURING THIS TIME AS WELL. WHILE SUNDAY MAY END UP BEING COMPLETELY DRY AS THE RIDGE CAPS THE AREA...IT DOES APPEAR THERE COULD BE A LAKE BREEZE ALONG THE IL SHORE SUNDAY AFTERNOON. HOW MUCH CONVERGENCE OCCURS IS UNCERTAIN BUT GIVEN HOW WARM/HUMID CONDITIONS WILL BE SUNDAY AFTERNOON...IF THIS IS ENOUGH FOR THUNDERSTORMS TO DEVELOP...THERE COULD BE SOME LOCALLY HEAVY RAIN ACROSS FAR NORTHEAST IL. ADDED SLIGHT CHANCE POPS DURING THIS TIME TO ACCOUNT FOR THIS POTENTIAL. DENSE FOG HAS FORMED ACROSS FAR NORTHEAST IL AND MAY SPREAD SOUTHWEST INTO NORTHWEST IL EARLY THIS MORNING AS RAIN ENDS. ISSUED A DENSE FOG ADVISORY FOR LAKE/MCHENRY COUNTIES EARLIER THIS MORNING AND MAY NEED TO EXPAND THAT AS TRENDS EMERGE. DEPENDING ON PRECIP COVERAGE TONIGHT...AREAS OF FOG POSSIBLY DENSE MAY DEVELOP AGAIN INTO SATURDAY MORNING. TEMPERATURES TODAY AND SATURDAY WILL BE DEPENDENT ON CLOUD COVER AND PRECIP COVERAGE. MADE ONLY SMALL TWEAKS...BASICALLY NO CHANGES. DID BUMP TEMPS UP A FEW DEGREES ON SUNDAY AND MONDAY WITH EXPECTED LESS OR NO PRECIP AND MORE SUNSHINE. OVERNIGHT LOWS WILL LIKELY REMAIN IN THE LOWER 70S MOST AREAS...POSSIBLY MID OR UPPER 70S DOWNTOWN CHICAGO SUNDAY NIGHT/MONDAY MORNING. FORECAST HEAT INDICES WILL BE NEAR 100 TODAY...RETREAT JUST A LITTLE SATURDAY AND THEN AGAIN NEAR 100 SUNDAY AND MONDAY. ACROSS THE SOUTHERN CWA...HEAT INDICES APPROACH THE 105 MARK. IF CURRENT TRENDS CONTINUE...ITS POSSIBLE PORTIONS OF THE SOUTHERN CWA MAY NEED A HEAT ADVISORY SUNDAY/MONDAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * BRIEF IFR CIG POSSIBLE NEXT 1-2 HRS. * VARIABLE SW WINDS TURNING NORTHEAST EARLY THIS AFTERNOON. SPEEDS EXPECTED TO BE UNDER 10 KT. * ISOLD-SCT SHRA/TSRA POSSIBLE MID/LATE AFTERNOON. MAY DEVELOP WEST OF TERMINALS AND DRIFT BACK TO THE EAST. * CHANCES FOR SHRA/TSRA TONIGHT AND SATURDAY MORNING...TIMING UNCLEAR. MDB //DISCUSSION...UPDATED 12Z... WEAK LOW PRESSURE EXTENDS FROM SOUTHERN MINNESOTA/NORTHERN IOWA SOUTHWEST INTO THE SOUTHERN PLAINS. A FRONTAL BOUNDARY EXTENDS FROM EASTERN IOWA ACROSS NORTHERN ILLINOIS TO NORTHERN INDIANA THIS MORNING WITH STRONG LOW LEVEL WINDS HELPING DRIVE THUNDERSTORM ACTIVITY TO THE SOUTH OF THE TERMINALS. SOME SPOTTY IFR IS IN PROXIMITY TO THE TERMINALS...WITH THE BULK NEAR RFD BUT THIS SHOULD BE IMPROVING...WITH ORD/MDW/DPA/GYY LIKELY SEEING LITTLE IF ANY IFR. LIGHT AND SOMEWHAT VARIABLE SOUTH TO SOUTHWEST WINDS ARE IN PLACE BUT ARE EXPECTED TO TURN EAST AND NORTHEAST THIS AFTERNOON AS THE FRONT RE-ESTABLISHES ITSELF PERHAPS WITH THE HELP OF LAKE MICHIGAN. THIS BOUNDARY COUPLED WITH THE VERY HUMID AIRMASS MAY TRIGGER ISOLD-SCT SHRA/TSRA THIS AFTERNOON INLAND OF THE LAKE WHICH WOULD THEN DRIFT BACK TOWARDS THE LAKE AFTER DEVELOPMENT. HAVE INCLUDED VCTS MENTION AT ORD/MDW/RFD/DPA WITH DECENT CONFIDENCE THAT ACTIVITY WILL OCCUR BUT WITH QUESTION MARKS SURROUNDING THE EXTENT. WINDS WILL DIMINISH THIS EVENING/TONIGHT WHICH MAY ALLOW SOME SHALLOW DENSE FOG OR MORE WIDESPREAD MVFR TYPE FOG. TSRA CHANCES REMAIN A CHALLENGE BUT HAVE PRETTY LOW CONFIDENCE IN WHEN THE BEST OPPORTUNITY WILL BE THIS EVENING THROUGH SATURDAY. WITH THE FRONTAL BOUNDARY EXPECTED TO BE IN THE REGION IT WOULD LIKELY SERVE AS A TRIGGER BUT IT MAY BE SOUTH OF THE AREA TONIGHT. UPPER RIDGING WILL BUILD IN SATURDAY WHICH WOULD BRING ANOTHER PUSH OF WARM AIR AND COUPLED WITH THE BOUNDARY WOULD PROBABLY DRIVE MORE TSRA DEVELOPMENT WHICH MAY BE FAVORED SATURDAY MORNING. WILL LEAVE THE TAF DRY BEYOND THIS AFTERNOON GIVEN THE UNCERTAINTY BUT HAVE DECENT CONFIDENCE THAT TSRA WILL OCCUR AT SOME POINT. MDB //ORD AND MDW CONFIDENCE...UPDATED 12Z... * HIGH CONFIDENCE THAT ANY IFR WOULD BE BRIEF. * HIGH CONFIDENCE IN LIGHT SW WINDS BECOMING NORTHEAST THIS AFTERNOON. MEDIUM-HIGH CONFIDENCE IN SPEEDS UNDER 10 KT. MEDIUM CONFIDENCE IN TIMING OF SHIFT TO NORTHEAST. * MEDIUM CONFIDENCE THAT THERE WILL BE SOME ISOLD/SCT SHRA/TSRA DEVELOPMENT THIS AFTERNOON. * LOW CONFIDENCE IN TIMING OF BEST SHRA/TSRA CHANCES THIS EVENING THROUGH SATURDAY MORNING BUT MEDIUM CONFIDENCE THAT ADDITIONAL ACTIVITY WILL OCCUR DURING THIS TIME. MDB //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... * SATURDAY NIGHT THROUGH THURSDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. MDB && .MARINE... 349 AM CDT AN ELONGATED AREA OF LOW PRESSURE STRETCHES FROM SOUTHERN MINNESOTA INTO THE SOUTHERN PLAINS WITH A WEAK WARM FRONTAL BOUNDARY STRETCHING FROM NORTHERN INDIANA BACK INTO CENTRAL/NORTHERN IOWA. THIS FRONT WILL MOVE LITTLE INTO SATURDAY. MORNING STORMS HAVE CAUSED WINDS TO BE A BIT CHAOTIC ACROSS THE FAR SOUTHERN PART OF THE LAKE WHERE SOUTH TO SOUTHEAST WINDS WILL TURN MORE EAST AND NORTHEAST INTO THE AFTERNOON. LOW PRESSURE WILL ORGANIZE ACROSS THE CENTRAL AND NORTHERN PLAINS LATER SATURDAY AND MOVE TO WESTERN ONTARIO SUNDAY ALLOWING WINDS TO TURN SOUTHERLY AND INCREASE IN SPEED TOWARD MONDAY. THE LOW WILL THEN TRACK TO THE NORTHEAST EARLY NEXT WEEK DRAGGING A FRONTAL BOUNDARY SOUTHWARD WHICH MAY STALL OUT SOMEWHERE ACROSS THE LAKE ALLOWING FOR VARIABLE WINDS. ANOTHER LOW IS EXPECTED TO LIFT NORTHEAST MID WEEK BRINGING A STRONGER COLD FRONT ACROSS THE LAKE WHICH WOULD BRING A SHIFT TO NORTH AND NORTHWEST WINDS. STILL EARLY FOR DETAILS BUT THIS SCENARIO WOULD BRING A PERIOD OF STRONGER WIND SPEEDS THANKS TO COLD ADVECTION...NOT UNLIKE SIMILAR COLD FRONTAL PASSAGES WE HAVE SEEN THE PAST FEW WEEKS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...DENSE FOG ADVISORY...ILZ005-ILZ006 UNTIL 10 AM FRIDAY. IN...NONE. LM...NONE. && $$ 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 NATIONAL WEATHER SERVICE LINCOLN IL 652 AM CDT Fri Aug 22 2014 .SHORT TERM...(Today and tonight) ISSUED AT 325 AM CDT FRI AUG 22 2014 07z/2am surface analysis shows a stationary front extending from west to east across northern Illinois. A 35kt LLJ has helped trigger a line of convection just south of that front. Those storms will affect our northern counties early this morning, with locally heavy rainfall rates possible. Areas near Midway airport last night picked up 3" in 30 minutes. There most likely will be a break in the rainfall for at least a few hours later this morning and early this afternoon, before the next shortwave over Iowa works its way into IL. Precipitable water values up near 2" will continue through the day, so any convection that redevelops this afternoon into evening will have the potential to produce very heavy rainfall. Coverage may not be too extensive during the day, so slight chance and low chance PoPs were used for areas north of I-72 after 7 am. The HRRR/NAM/GFS/ECMWF all show an enhanced opportunity for storms either later this afternoon or this evening as an MCS develops to our west and rolls across N IL. With timing still in question, we did not ramp up to likely PoPs in any one area even this evening and overnight. The main theme does seem to be that the northern half of the KILX CWA will be the main target area for storms over the next 24-36 hours. High temps today will once again climb into the upper 80s to low 90s, with dewpoints already in the mid 70s and likely to climb into the upper 70s in some areas. Heat index readings will likely climb to around 105 in southern areas. We can not rule out the possible need to expand the heat advisory northward. Precip and cloud cover across the north should keep their heat index readings below advisory levels in general. && .LONG TERM...(Saturday through Thursday) ISSUED AT 325 AM CDT FRI AUG 22 2014 Main issue through the extended remains the extreme heat for this time of year through the weekend and into the first portion of next week. Models still having issues with the ultimate breaking down of the ridge, resulting in a potential extension to the heat wave should the trend continue. Hot daytime highs into the 90s and dewpoints into the mid 70s resulting in heat indices over 100F for several days on end. Scattered chances exist as long as the boundary remains close to the FA...and will be the only chance for brief cool downs. But as the high builds into the region, the general subsidence will be hard to overcome, so the forecast for Saturday night through Sunday night is dry for now...with some slight chances coming back for Monday...but the models struggling with the solutions in the mid range with the timing of a vigorous wave to erode the ridge. GFS still far more aggressive, amplified, and fast with the passage of the upper trof/sfc front Tues night into Wednesday. ECMWF starting to close the gap and has abandoned the closed low of 24 hrs ago... but is still signif weaker, resulting in a developing baroclinic zone at the sfc as the wave fizzles in parallel flow and provides a focus for a longer duration potential for precip. Model blends now through the mid/end of next week results in more widespread chances. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 652 AM CDT FRI AUG 22 2014 A nocturnal LLJ has helped fuel an east-west line of storms across north-central IL. The storms with heavy rainfall will affect mainly PIA, BMI and CMI early this morning, bringing MVFR vis and ceilings. BMI has dropped to IFR cloud height, which could linger through 15z before lifting to MVFR. A break in the storms is indicated for the terminal sites for late morning into afternoon in the HRRR and RAP model output. Additional storm chances are indicated for later this afternoon and evening for the northern TAF sites of PIA, BMI and CMI. We kept precip our of DEC and SPI for now, but trends are for storms to get quite close even this morning. Will monitor closely for changes to the dry forecast for SPI/DEC. Winds will generally remain S-SW in the synoptic flow across our area, south of the warm front. Local northerly winds have developed for the northern terminals where the storms have produced an outflow boundary moving south. The outflow could even reach SPI and DEC, but wind speeds by then should be 10kt or less. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY from 1 PM this afternoon to 7 PM CDT Monday FOR ILZ042-047>054-056-061>063-066>068-071>073. && $$ SHORT TERM...SHIMON LONG TERM...HJS AVIATION...SHIMON
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1028 AM EDT FRI AUG 22 2014 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 235 AM EDT FRI AUG 22 2014 AN ACTIVE AND WARM WEATHER PATTERN WILL REMAIN IN PLACE THROUGH THE WEEKEND AS A RIDGE OF HIGH PRESSURE BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY. THIS WILL ALLOW VERY WARM AND HUMID AIR TO PUSH INTO THE OHIO VALLEY. MEANWHILE...SEVERAL UPPER LEVEL WEATHER DISTURBANCES ARE EXPECTED TO PUSH INTO NORTHERN AND CENTRAL INDIANA ALONG A LINGERING FRONTAL BOUNDARY. THIS WILL RESULT IN DAILY CHANCES FOR SHOWERS OR STORMS THROUGH THE WEEKEND. NEXT WEEK ANOTHER FRONTAL SYSTEM WILL BRING ADDITIONAL CHANCES FOR RAIN AND WILL EVENTUALLY BRING A RETURN TO NEAR AVERAGE TEMPERATURES. && .NEAR TERM /TODAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 SURFACE ANALYSIS EARLY THIS MORNING SHOWS A WARM FRONTAL BOUNDARY IN PLACE ACROSS NORTHERN AND CENTRAL INDIANA...STRETCHING FROM NEAR CHICAGO TO MUNCIE AND WINCHESTER. RADAR CONTINUES TO SHOW SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. ALOFT A RIDGE OF HIGH PRESSURE WAS IN PLACE OVER THE LOWER MISSISSIPPI RIVER VALLEY...ALLOWING FOR UPPER LEVEL WEATHER DISTURBANCES TO RIDE THE RIDGE AND SPILL ACROSS THE WARM FRONT ACROSS THE NORTHERN AND CENTRAL INDIANA...ALL THE WHILE BEING A TRIGGER FOR TSRA. MEANWHILE...A VERY WARM AND MOIST AIR MASS REMAINS IN PLACE ACROSS CENTRAL INDIANA WITH DEW POINTS IN THE UPPER 60S AND LOWER 70S. SKIES WERE CLOUDY...FILLED WITH DEBRIS FROM EARLIER CONVECTION. MAIN FORECAST CHALLENGE TODAY WILL BE POPS. GFS AND NAM AGREE TO AN AMPLIFICATION OF THE UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY TODAY...HOWEVER THIS WILL STILL RESULT IN MORE OF THE SAME AS THE UPPER FLOW WILL BE POISED TO SPILL ALONG THE LINGERING FRONTAL BOUNDARY ACROSS CENTRAL AND NORTHERN INDIANA. FORECAST SOUNDINGS ACROSS THE AREA TODAY CONTINUE TO SHOW PLENTY OF MOISTURE AVAILABLE WITH OVER 2 INCHES OF PRECIPITABLE WATER. FORECAST SOUNDINGS ALSO IMPLY CONDITIONAL INSTABILITY WITH CAPE IN EXCESS OF 200 J/KG...HOWEVER CONVECTIVE TEMPS ARE IN THE LOWER 90S...WHICH SEEM A LITTLE HIGH. CONFIDENCE REMAINS LOW IN ANY SPECIFIC TIMING FOR TSRA TODAY AS GFS AND NAM BOTH FAIL TO SUGGEST ANY SPECIFIC ORGANIZED WAVE TO PASS ALOFT. HRRR DOES SUGGEST CONVECTION ACROSS THE NORTHERN PARTS OF THE FORECAST AREA THIS MORNING...AN GIVEN THE LATEST RADAR TRENDS WILL STEER TOWARD THIS SOLUTION. HOWEVER GIVEN THE MOIST AIR MASS IN PLACE ALONG WITH THE LINGERING FRONTAL BOUNDARY...WILL KEEP POPS IN PLACE THROUGH THE DAY. AS FOR TEMPS...WITH CLOUDS AND POSSIBLE RAIN TODAY...WILL TREND TOWARD PERSISTENCE...WHICH SHOULD BE COOLER THAN MAVMOS. WARMER TEMPS WILL BE FOUND ACROSS THE SW FORECAST AREA WHERE POPS CHANCES AND CLOUDS WILL BE MUCH LESS...DUE TO PROXIMITY TO THE FRONT. && .SHORT TERM /TONIGHT THROUGH MONDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 GFS AND NAM SUGGEST LITTLE OVERALL CHANGE IN THE ONGOING PATTERN TONIGHT AND SATURDAY. THE UPPER RIDGE TO THE WEST CONTINUES TO ALLOW WEAK UPPER DISTURBANCES TO SPILL SOUTHEAST INTO INDIANA. THE WARM...HUMID AND CONDITIONALLY UNSTABLE AIRMASS REMAINS IN PLACE. FORECAST SOUNDINGS REMAIN DEEPLY SATURATED WITH VERY HIGH PRECIPITABLE WATER VALUES. LINGERING SURFACE BOUNDARY REMAINS IN PLACE ALSO. THUS WILL RAISE POPS TONIGHT AND ON SATURDAY AS THESE FEATURES CONTINUE TO REMAIN IN PLACE. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL CONTINUE TO TREND OF LEANING WARMER THAN MAVMOS ON LOWS AND COOLER ON HIGHS. ON SATURDAY NIGHT THROUGH MONDAY...THE UPPER RIDGE AXIS BEGINS TO DRIFT EAST...WHICH BEGINS TO ALLOW DRIER AIR TO ENTER THE FORECAST COLUMN. THE UPPER STEERING FLOW BEGINS TO SHIFT ANY RIDGE RIDING SHORT WAVES WELL EAST OF INDIANA. WITH ET DRIER AIR ARRIVING PRECIPITABLE WATER IN THE FORECAST SOUNDINGS FALLS TO LESS THAN 1.75 IN. ALSO 700MB TEMPS RISE TOWARD 10C...OFTEN A KEY CAPPING TEMPERATURE. THUS WILL TREND POPS AT OR BELOW MAVMOS ON SUNDAY THROUGH MONDAY. AS FOR TEMPS...WILL TREND HIGHS AND LOWS WARMER THAN MAVMOS GIVEN THE VERY WARM AIR MASS THAT IS EXPECTED ACROSS THE AREA. && .LONG TERM /MONDAY NIGHT THROUGH NEXT THURSDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 ENSEMBLES SUGGEST UPPER RIDGE INITIALLY OVER THE AREA AT THE BEGINNING OF THE PERIOD WILL EVENTUALLY GET SUPPRESSED BACK TO THE SOUTH AS AN UPPER TROUGH MOVES INTO THE NORTHERN MIDWEST OR GREAT LAKES BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST PRECIPITATION POTENTIAL WILL MOVE BACK INTO THE AREA STARTING NEXT TUESDAY AS UPPER RIDGE BEGINS TO FLATTEN OUT...WITH THE BEST CHANCES NEXT WEDNESDAY AND THURSDAY AS A FRONTAL SYSTEM ASSOCIATED WITH THE APPROACHING UPPER TROUGH MOVES IN. WILL KEEP CHANCE POPS GOING IN THE FORECAST FROM TUESDAY THROUGH NEXT THURSDAY. && .AVIATION /DISCUSSION FOR THE 221500Z TAF UPDATE/... ISSUED AT 1028 AM EDT FRI AUG 22 2014 AREA OF THUNDERSTORMS HAS WEAKENED SO HAVE PULLED IMMEDIATE THUNDER THREAT FROM THE TAFS. THERE ARE SOME AREAS OF PATCHY MVFR BOTH IN AND OUT OF THE RAIN AREAS...SO HAVE PUT TEMPOS IN TO COVER THIS. MUCH UNCERTAINTY EXISTS IN HOW CONVECTIVE SITUATION WILL EVOLVE UPSTREAM...SO HAVE JUST PUT IN VCTS AT KIND AND KHUF FOR THE AFTERNOON. PREVIOUS DISCUSSION FOLLOWS... THUNDERSTORM CLUSTERS CONTINUE TO DROP SOUTHEAST ACROSS NORTHERN ILLINOIS AND NORTHERN INDIANA. INTENSITY HAS FOR THE MOST PART BEEN FAIRLY STEADY...ALTHOUGH CLOUD TOPS HAVE SHOWN A TENDENCY TO COOL OVER THE PAST HOUR. PROFILERS STILL SHOWING DECENT INFLOW OF 25-30 KTS INTO THE CLUSTERS...SO EXPECTING CONVECTION TO CONTINUE FOR AWHILE LONGER BEFORE WEAKENING LATER THIS MORNING. APPEARS KLAF/KIND AND PROBABLY KHUF HAVE A GOOD CHANCE OF A DIRECT IMPACT FROM CONVECTION THROUGH ABOUT 221600Z...WITH LOWER CONFIDENCE AT KBMG. PERIODS OF IFR VISIBILITY RESTRICTIONS EXPECTED IN THE HEAVIER CELLS. SHOULD SEE A BREAK IN THE CONVECTIVE THREAT AROUND MIDDAY INTO THE AFTERNOON HOURS...BUT MODELS SUGGEST A RENEWED THREAT AFTER ABOUT 222100Z-222200Z AND ON INTO THE EVENING HOURS WITH A POTENTIAL UPPER WAVE MOVING OUT OF THE IOWA REGION. OUTSIDE OF CONVECTION...CEILINGS GENERALLY ABOVE 050 TODAY WITH SURFACE WINDS 210-240 AT 6-8 KTS. VARIABLE AND GUSTY WINDS ALONG WITH LOWER CEILINGS IN AND NEAR CONVECTION. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM...JAS AVIATION...JAS/50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSINDIANAPOLIS WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
630 AM EDT FRI AUG 22 2014 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 235 AM EDT FRI AUG 22 2014 AN ACTIVE AND WARM WEATHER PATTERN WILL REMAIN IN PLACE THROUGH THE WEEKEND AS A RIDGE OF HIGH PRESSURE BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY. THIS WILL ALLOW VERY WARM AND HUMID AIR TO PUSH INTO THE OHIO VALLEY. MEANWHILE...SEVERAL UPPER LEVEL WEATHER DISTURBANCES ARE EXPECTED TO PUSH INTO NORTHERN AND CENTRAL INDIANA ALONG A LINGERING FRONTAL BOUNDARY. THIS WILL RESULT IN DAILY CHANCES FOR SHOWERS OR STORMS THROUGH THE WEEKEND. NEXT WEEK ANOTHER FRONTAL SYSTEM WILL BRING ADDITIONAL CHANCES FOR RAIN AND WILL EVENTUALLY BRING A RETURN TO NEAR AVERAGE TEMPERATURES. && .NEAR TERM /TODAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 SURFACE ANALYSIS EARLY THIS MORNING SHOWS A WARM FRONTAL BOUNDARY IN PLACE ACROSS NORTHERN AND CENTRAL INDIANA...STRETCHING FROM NEAR CHICAGO TO MUNCIE AND WINCHESTER. RADAR CONTINUES TO SHOW SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. ALOFT A RIDGE OF HIGH PRESSURE WAS IN PLACE OVER THE LOWER MISSISSIPPI RIVER VALLEY...ALLOWING FOR UPPER LEVEL WEATHER DISTURBANCES TO RIDE THE RIDGE AND SPILL ACROSS THE WARM FRONT ACROSS THE NORTHERN AND CENTRAL INDIANA...ALL THE WHILE BEING A TRIGGER FOR TSRA. MEANWHILE...A VERY WARM AND MOIST AIR MASS REMAINS IN PLACE ACROSS CENTRAL INDIANA WITH DEW POINTS IN THE UPPER 60S AND LOWER 70S. SKIES WERE CLOUDY...FILLED WITH DEBRIS FROM EARLIER CONVECTION. MAIN FORECAST CHALLENGE TODAY WILL BE POPS. GFS AND NAM AGREE TO AN AMPLIFICATION OF THE UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY TODAY...HOWEVER THIS WILL STILL RESULT IN MORE OF THE SAME AS THE UPPER FLOW WILL BE POISED TO SPILL ALONG THE LINGERING FRONTAL BOUNDARY ACROSS CENTRAL AND NORTHERN INDIANA. FORECAST SOUNDINGS ACROSS THE AREA TODAY CONTINUE TO SHOW PLENTY OF MOISTURE AVAILABLE WITH OVER 2 INCHES OF PRECIPITABLE WATER. FORECAST SOUNDINGS ALSO IMPLY CONDITIONAL INSTABILITY WITH CAPE IN EXCESS OF 200 J/KG...HOWEVER CONVECTIVE TEMPS ARE IN THE LOWER 90S...WHICH SEEM A LITTLE HIGH. CONFIDENCE REMAINS LOW IN ANY SPECIFIC TIMING FOR TSRA TODAY AS GFS AND NAM BOTH FAIL TO SUGGEST ANY SPECIFIC ORGANIZED WAVE TO PASS ALOFT. HRRR DOES SUGGEST CONVECTION ACROSS THE NORTHERN PARTS OF THE FORECAST AREA THIS MORNING...AN GIVEN THE LATEST RADAR TRENDS WILL STEER TOWARD THIS SOLUTION. HOWEVER GIVEN THE MOIST AIR MASS IN PLACE ALONG WITH THE LINGERING FRONTAL BOUNDARY...WILL KEEP POPS IN PLACE THROUGH THE DAY. AS FOR TEMPS...WITH CLOUDS AND POSSIBLE RAIN TODAY...WILL TREND TOWARD PERSISTENCE...WHICH SHOULD BE COOLER THAN MAVMOS. WARMER TEMPS WILL BE FOUND ACROSS THE SW FORECAST AREA WHERE POPS CHANCES AND CLOUDS WILL BE MUCH LESS...DUE TO PROXIMITY TO THE FRONT. && .SHORT TERM /TONIGHT THROUGH MONDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 GFS AND NAM SUGGEST LITTLE OVERALL CHANGE IN THE ONGOING PATTERN TONIGHT AND SATURDAY. THE UPPER RIDGE TO THE WEST CONTINUES TO ALLOW WEAK UPPER DISTURBANCES TO SPILL SOUTHEAST INTO INDIANA. THE WARM...HUMID AND CONDITIONALLY UNSTABLE AIRMASS REMAINS IN PLACE. FORECAST SOUNDINGS REMAIN DEEPLY SATURATED WITH VERY HIGH PRECIPITABLE WATER VALUES. LINGERING SURFACE BOUNDARY REMAINS IN PLACE ALSO. THUS WILL RAISE POPS TONIGHT AND ON SATURDAY AS THESE FEATURES CONTINUE TO REMAIN IN PLACE. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL CONTINUE TO TREND OF LEANING WARMER THAN MAVMOS ON LOWS AND COOLER ON HIGHS. ON SATURDAY NIGHT THROUGH MONDAY...THE UPPER RIDGE AXIS BEGINS TO DRIFT EAST...WHICH BEGINS TO ALLOW DRIER AIR TO ENTER THE FORECAST COLUMN. THE UPPER STEERING FLOW BEGINS TO SHIFT ANY RIDGE RIDING SHORT WAVES WELL EAST OF INDIANA. WITH ET DRIER AIR ARRIVING PRECIPITABLE WATER IN THE FORECAST SOUNDINGS FALLS TO LESS THAN 1.75 IN. ALSO 700MB TEMPS RISE TOWARD 10C...OFTEN A KEY CAPPING TEMPERATURE. THUS WILL TREND POPS AT OR BELOW MAVMOS ON SUNDAY THROUGH MONDAY. AS FOR TEMPS...WILL TREND HIGHS AND LOWS WARMER THAN MAVMOS GIVEN THE VERY WARM AIR MASS THAT IS EXPECTED ACROSS THE AREA. && .LONG TERM /MONDAY NIGHT THROUGH NEXT THURSDAY/... ISSUED AT 235 AM EDT FRI AUG 22 2014 ENSEMBLES SUGGEST UPPER RIDGE INITIALLY OVER THE AREA AT THE BEGINNING OF THE PERIOD WILL EVENTUALLY GET SUPPRESSED BACK TO THE SOUTH AS AN UPPER TROUGH MOVES INTO THE NORTHERN MIDWEST OR GREAT LAKES BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST PRECIPITATION POTENTIAL WILL MOVE BACK INTO THE AREA STARTING NEXT TUESDAY AS UPPER RIDGE BEGINS TO FLATTEN OUT...WITH THE BEST CHANCES NEXT WEDNESDAY AND THURSDAY AS A FRONTAL SYSTEM ASSOCIATED WITH THE APPROACHING UPPER TROUGH MOVES IN. WILL KEEP CHANCE POPS GOING IN THE FORECAST FROM TUESDAY THROUGH NEXT THURSDAY. && .AVIATION /DISCUSSION FOR THE 221200Z TAFS/... ISSUED AT 630 AM EDT FRI AUG 22 2014 THUNDERSTORM CLUSTERS CONTINUE TO DROP SOUTHEAST ACROSS NORTHERN ILLINOIS AND NORTHERN INDIANA. INTENSITY HAS FOR THE MOST PART BEEN FAIRLY STEADY...ALTHOUGH CLOUD TOPS HAVE SHOWN A TENDENCY TO COOL OVER THE PAST HOUR. PROFILERS STILL SHOWING DECENT INFLOW OF 25-30 KTS INTO THE CLUSTERS...SO EXPECTING CONVECTION TO CONTINUE FOR AWHILE LONGER BEFORE WEAKENING LATER THIS MORNING. APPEARS KLAF/KIND AND PROBABLY KHUF HAVE A GOOD CHANCE OF A DIRECT IMPACT FROM CONVECTION THROUGH ABOUT 221600Z...WITH LOWER CONFIDENCE AT KBMG. PERIODS OF IFR VISIBILITY RESTRICTIONS EXPECTED IN THE HEAVIER CELLS. SHOULD SEE A BREAK IN THE CONVECTIVE THREAT AROUND MIDDAY INTO THE AFTERNOON HOURS...BUT MODELS SUGGEST A RENEWED THREAT AFTER ABOUT 222100Z-222200Z AND ON INTO THE EVENING HOURS WITH A POTENTIAL UPPER WAVE MOVING OUT OF THE IOWA REGION. OUTSIDE OF CONVECTION...CEILINGS GENERALLY ABOVE 050 TODAY WITH SURFACE WINDS 210-240 AT 6-8 KTS. VARIABLE AND GUSTY WINDS ALONG WITH LOWER CEILINGS IN AND NEAR CONVECTION. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM...JAS AVIATION...JAS VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSINDIANAPOLIS WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
634 AM CDT FRI AUG 22 2014 .SYNOPSIS... ISSUED AT 328 AM CDT FRI AUG 22 2014 ALOFT...UPPER RIDGE PERSISTS OVER THE MISSISSIPPI VALLEY. SURFACE LOW NEAR KLSE THIS MORNING WITH A STATIONARY FRONT EXTENDING TO ITS SOUTHWEST INTO COLORADO AND ALSO TO ITS EAST INTO THE GREAT LAKES. THUNDERSTORMS THIS MORNING FUELED BY LLJ...WARM SECTOR DEW POINTS IN THE 70S...AND APPROACHING MCV. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 328 AM CDT FRI AUG 22 2014 AREA OF CONVECTION OVER SOUTH CENTRAL IOWA SHOULD PERSIST THROUGH SUNRISE AND AFFECT SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. SHORT RANGE MODELS INCLUDING THE HRRR AND RUC WEAKEN THE CONVECTION AFTER SUNRISE...WHICH MAKES SENSE GIVEN THE DIURNAL TREND OF THE LLJ. HOWEVER...MODELS HAVE TYPICALLY BEEN TOO QUICK TO SQUELCH CONVECTION...AND THUS BELIEVE IT WILL LINGER A BIT LONGER THAN PROGGED AND WILL HANG ON TO POPS IN THE SOUTHERN HALF OF THE CWFA LONGER THAN MESOSCALE MODELS WOULD SUGGEST. ANOTHER ROUND OF STORMS EXPECTED THIS AFTERNOON AS THE SURFACE LOW CONTINUES TO SAG EVER SO SLIGHTLY FARTHER SOUTH AND THE FRONT REMAINS STALLED OVER NRN MO/SRN IA. OF COURSE EXACT POSITIONING OF STORMS REMAINS UNCERTAIN...IN PARTICULAR WITH SO MANY BOUNDARIES AROUND. CURRENT THINKING IS THAT FAVORED AREA IS ALONG AND JUST SOUTH OF I80 WHERE THE 850 MB FRONT IS PROGGED TO SET UP. REGARDLESS OF EXACT LOCATION...EXPECT INTENSE RAINFALL RATES DUE TO HIGH PRECIPITABLE WATERS AT OR ABOVE 2 INCHES. ACTIVE WEATHER CONTINUES THROUGH TONIGHT WITH BOUNDARIES LINGERING AND POTENTIAL FOR UPPER WAVES COMING OUT OF THE WSW. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 328 AM CDT FRI AUG 22 2014 THE PERSISTENT RING OF FIRE PATTERN CONTINUES THROUGH THE WEEKEND PRESENTING A THREAT FOR HOT AND HUMID CONDITIONS OUTSIDE THE OCCASIONAL MESOSCALE CONVECTIVE COMPLEXES LIKELY TO IMPACT PARTS OF THE REGION. THE UPPER LEVEL RIDGE IS THEN EXPECTED TO BREAK DOWN AND SHIFT EASTWARD BY THE MIDDLE PART OF NEXT WEEK. THIS WILL ALLOW CANADIAN HIGH PRESSURE TO BUILD INTO THE AREA...RETURNING TEMPERATURES CLOSER TO LATE AUGUST NORMALS AND PROVIDING A PERIOD OF DRIER WEATHER. SATURDAY AND SUNDAY...LOW PRESSURE LIFTING NORTHEAST THROUGH THE NORTHERN PLAINS WILL LIFT THE LOW LEVEL BOUNDARY/WARM FRONT NORTHWARD THROUGH THE FORECAST AREA SATURDAY. THE ASSOCIATED WARM ADVECTION AND STRENGTHENING MID LEVEL CAP WILL LIMIT THUNDERSTORM CHANCES TO THE NORTHEAST HALF OF THE FORECAST AREA. WITH DEW POINTS EASILY IN THE LOWER TO MID 70S...VERY MUGGY CONDITIONS WILL CONTINUE. MAX TEMPERATURES WILL CONTINUE TO BE A CHALLENGE DUE TO UNCERTAINTY IN CONVECTIVE TRENDS AND ASSOCIATED CLOUD COVER. WITH SURFACE WINDS MORE SOUTHEASTERLY...WILL BIAS TOWARD THE LOWER END OF GUIDANCE WITH HIGHS FROM THE MID 80S NORTHEAST TO LOWER 90S SOUTH. THIS WOULD STILL RESULT IN HEAT INDEX READINGS NEAR TO JUST ABOVE 100 SOUTH OF I-80 IN THE AFTERNOON HOURS. SATURDAY NIGHT THROUGH SUNDAY...THE AREA WILL FALL INTO THE MORE DEEPLY MIXED BUT CAPPED WARM SECTOR WITH 850 MB TEMPERATURES SUPPORTIVE OF WIDESPREAD HIGHS IN THE UPPER 80S TO LOWER 90S AND POSSIBLY WARMER DEPENDING ON THE AMOUNT OF CLOUD COVER. THIS WOULD RESULT IN POSSIBLY ANOTHER DAY OF 100 PLUS HEAT INDEX VALUES AND MAY REQUIRE HEAT HEADLINES OVER AT LEAST THE SOUTH. MONDAY THROUGH THURSDAY...MODEL SOLUTIONS CONTINUE TO DIFFER IN THE TIMING OF THE BOTH THE INITIAL EARLY WEEK FRONTAL PASSAGE AND THE STRONGER COLD FRONT AROUND WED AND THU. THE ECMWF AND CANADIAN HAVE THE INITIAL FRONT PUSHING THROUGH INTO CENTRAL IL AND MO MONDAY...WHILE THE GFS HOLDS IT WELL TO THE NW. OUR FORECAST WILL CONTINUE A LOW CONFIDENCE BLENDED APPROACH WITH THUNDERSTORM CHANCES RETURNING LATE MONDAY AND CONTINUING THROUGH THURSDAY. THE PAST COUPLE RUNS WERE TRENDING TOWARD A GREATER LIKELIHOOD OF A DRY THURSDAY AS HIGH PRESSURE BUILDS IN. WARM TO VERY WARM AND CONTINUED HIGH HUMIDITY SUGGEST A POSSIBLE NEED FOR HEAT HEADLINES AT LEAST IN THE AFTERNOON HOURS FOR MONDAY AND TUESDAY WHERE HIGHS ARE MAINTAINED IN THE UPPER 80S TO LOWER 90S WITH OVERNIGHT LOWS HOLDING IN THE 70S FOR MUCH OF THE AREA. TEMPERATURES ARE TRENDING A BIT COOLER...FOR WED AND THU AS THE CONTINUITY IN SUCCESSIVE MODEL RUNS BACK THE TIMING OF THE PATTERN CHANGE AND PLACEMENT OF THE IN-COMING HIGH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 627 AM CDT FRI AUG 22 2014 PATCHY DENSE FOG AFFECTING KCID AND KDBQ WILL LIFT BY MID MORNING. MEANWHILE...THUNDERSTORMS WILL AFFECT KBRL THIS MORNING AND SHOWERS WILL MOVE INTO KMLI. LATER TODAY...ANOTHER ROUND OF STORMS IS POSSIBLE THIS AFTERNOON AND EVENING AT ALL AREA TAF SITES...BUT THE GREATEST CHANCE IS FOR AREAS MAINLY SOUTH OF I 80. OTHERWISE...PREVAILING WINDS WILL BE LIGHT AND VARIABLE WITH GUSTS NEAR THUNDERSTORMS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...DMD
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1200 PM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 1200 PM EDT FRI AUG 22 2014 15Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE THROUGH THE DEEP SOUTH WITH GENERAL LOW PRESSURE TO THE NORTH AND WEST OF THIS AREA. THIS PLACES EAST KENTUCKY ON THE NORTHERN FRINGE OF THE SFC RIDGE AND ALSO THE NORTHEAST EDGE OF THE MID LEVEL ONE PARKED TO THE SOUTHWEST OF THE AREA. THE STORM TRACK...LIKE THOSE PAST COUPLE OF DAYS...IS PRETTY CLEAR AS CONVECTIVE CLUSTERS DEVELOP IN NORTHERN ILLINOIS AND INDIANA...ROLLING SOUTHEAST INTO OHIO BEFORE HITTING THE APPALACHIANS AT WEST VIRGINIA. THE BEST INSTABILITY REMAINS TO THE SOUTH AND WEST OF THIS TRACK...LEADING TO A TENDENCY FOR THESE SYSTEMS TO ARC TO THE SOUTH INTO EASTERN KENTUCKY OR KICKING OFF OUTFLOW BOUNDARIES STRONG ENOUGH TO INITIATE NEW DEVELOPMENT. THE LATEST HIGH RESOLUTION NEAR TERM MODELS INCLUDING THE HRRR AND 12Z NAM12 SUGGEST THAT BOTH SCENARIOS ARE POSSIBLE THIS AFTERNOON WITH THE FORMER FOCUSING ON SCATTERED DEVELOPMENT THROUGH THE CWA AFTER 18Z AND PERHAPS A MORE ORGANIZED SYSTEM ARRIVING FROM THE NORTHWEST AFTER 21Z. THE NAM12 FOCUSES ON THE NORTHWEST SYSTEM AND HAS IT PUSH INTO EAST KENTUCKY BETWEEN 18 AND 21Z WITH LESS AIR MASS CONVECTION AHEAD OF IT. ALOFT...THE GENESIS WAVE APPEARS TO PASS THROUGH THE SOUTHERN OHIO VALLEY BY 21Z SO THE NAM12 WITH ITS EARLIER ARRIVAL APPEARS TO BE REASONABLE. HIGH PWS AGAIN TODAY ALONG WITH GOOD INSTABILITY SUGGEST THE POTENTIAL FOR FLASH FLOODING...ESPECIALLY FOR PLACES THAT SEE TRAINING...ALONG WITH STRONG TO MARGINALLY SEVERE STORMS WITH DAMAGING WIND GUSTS AS THE MAIN THREAT. HAVE UPDATED TO CONVEY THIS IN THE SKY...POP...QPF...AND WX GRIDS. EAST KENTUCKY WILL ALSO HAVE A CONTINUANCE OF THE HOT AND HUMID CONDITIONS WITH HIGHS AROUND 90...SUBJECT TO THUNDERSTORM INDUCED COOL DOWNS...AND DEWPOINTS IN THE STEAMY LOW TO MID 70S. A NEW SET OF ZONES WERE ISSUED TO REFLECT THE ABOVE AND THE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 810 AM EDT FRI AUG 22 2014 THE FORECAST REMAINS ON TRACK THIS MORNING. SHOWERS AND THUNDERSTORMS WILL LIKELY STEER CLEAR OF THE AREA UNTIL MAINLY THIS AFTERNOON. FRESHENED UP THE SKY COVER AND HOURLY TEMPERATURES AND DEW POINTS TO ALIGN BETTER WITH THE LATEST TRENDS IN OBSERVATIONS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 400 AM EDT FRI AUG 22 2014 THE LATEST SURFACE MAP FEATURES SURFACE HIGH PRESSURE ACROSS THE GULF COAST STATES...WITH BROADENING LOW PRESSURE ACROSS THE PLAINS. A STATIONARY FRONTAL BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO VALLEY. ALOFT...AN UPPER LEVEL RIDGE IS CURRENTLY CENTERED NEAR LOUISIANA WITH ITS INFLUENCE EXTENDING FURTHER NORTH INTO THE MISSISSIPPI VALLEY. TROUGHING REMAINS POISED ACROSS THE WESTERN CONUS. THUNDERSTORM COMPLEXES CONTINUE TO GEN UP ON THE NORTHERN PERIPHERY OF THE RIDGE AXIS AND THEN PROCEED TO ADVANCE ESE ACROSS THE OHIO VALLEY. CURRENTLY...A WEAKENING COMPLEX IS SKIRTING NORTHEASTERN KENTUCKY...LIKELY CLEARING OUR FORECAST AREA IN THE NEXT 2 TO 3 HOURS. THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...WITH THE UPPER LEVEL RIDGE GRADUALLY AMPLIFYING ACROSS THE MISSISSIPPI VALLEY. DETAILS ASSOCIATED WITH CONVECTIVE INITIATION CONTINUE TO BE PROBLEMATIC HOWEVER...AND HAVE STUCK WITH A GENERAL MODEL BLEND...WHICH FAVORS MORE VIGOROUS CONVECTION DURING THE WARMER PART OF THE DAY. TODAY LOOKS TO BE SOMEWHAT OF A REPEAT OF YESTERDAY...WITH STOUT INSTABILITY BUILDING BY EARLY THIS AFTERNOON. WHILE THE MCS TRACK HAS SHIFTED A BIT FURTHER NORTHEAST TODAY COMPARED TO YESTERDAY...OUTFLOW BOUNDARIES CONTINUE TO BE THE MAIN PLAYER...LEAVING MOST LOCATIONS IN THE LINE OF FIRE AT SOME POINT. SOME SEVERE THUNDERSTORMS CAN NOT BE RULED OUT ONCE AGAIN TODAY...ALONG WITH ISOLATED FLASH FLOODING...WHERE STORMS CAN ALIGN ALONG OUTFLOW BOUNDARIES PARALLEL TO THE STEERING FLOW. ANOTHER HOT AND HUMID DAY LOOKS TO BE ON TAP...WITH A FEW SPOTS NEARING THE 100 DEGREE MARK IN HEAT INDICES. STORMS WILL GRADUALLY WEAKEN INTO THE EVENING HOURS...ALTHOUGH SOME NOCTURNAL ACTIVITY REMAINS AT LEAST SOMEWHAT OF A POSSIBILITY. LOWS WILL BE MUGGY ONCE AGAIN AROUND THE 70 DEGREE MARK. SATURDAY WILL FEATURE ANOTHER WARM AND HUMID DAY...ALONG WITH THE THREAT OF MORE SCATTERED CONVECTION ACROSS THE AREA. THERE WILL BE LESS INSTABILITY AVAILABLE AS MID-LEVEL WARMING TAKES PLACE FROM THE INFLUENCE OF THE UPPER RIDGE. THIS WILL KEEP THE SEVERE AND FLASH FLOOD THREAT LOWER. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 400 AM EDT FRI AUG 22 2014 UPPER LEVEL RIDGING WILL REMAIN IN PLAY DURING THE DURATION OF THE EXTENDED...WITH HEIGHTS EXPECTED TO BUILD AS THE HIGH SHIFTS NEWARD ACROSS THE OHIO RIVER VALLEY. BUILDING HEIGHTS WILL THEN TRANSLATE TO RISING TEMPERATURES. HOWEVER...MID AND UPPER LEVEL WINDS WILL GENERALLY REMAIN OUT OF THE NORTH DURING THE FIRST FEW DAYS OF THE EXTENDED. THIS...COUPLED WITH CLOUD COVER THAT WILL HAMPER MAXIMUM SOLAR RADIATION...WILL KEEP HIGHS IN THE MID AND UPPER 80S THROUGH TUESDAY. TEMPS MAY THEN COOL DOWN A COUPLE DEGREES AFTER TUESDAY AS HIGH PRESSURE SITS OVERHEAD AND UPPER LEVEL HEIGHTS ASSOCIATED WITH THE RIDGE BECOME MORE STATIC. BASED ON THE LATEST FORECAST SOUNDINGS...WILL AGREE WITH PREVIOUS FORECAST THAT EACH DAY SHOULD POSE A SHOWER/THUNDERSTORM THREAT MAINLY IN THE AFTERNOON AND EVENING. GIVEN THE MID LEVEL DRYING FROM MONDAY ON...WOULDN/T BE SURPRISED IF SOME OF THESE STORMS PRODUCE SOME POTENTIAL HAIL. IN PROMISING NEWS...WITH THE RIDGING PATTERN IN PLACE...WE WILL EXPERIENCE NO BOUNDARY FORCING UNTIL VERY LATE IN THE FORECAST...SO THIS WILL HAMPER SOME OF THE BEST INSTABILITY AND WIDESPREAD INITIATION. WINDS WILL BE LIGHT AT THE SURFACE...AND REMAIN SO AS WE HEAD UP HIGHER INTO THE ATMOSPHERE. THAT BEING SAID...AFTERNOON CAPE VALUES WILL BE ABOVE THE 2K J/KG RANGE THROUGH MUCH OF THE EXTENDED...AND LAPSE RATES WILL RISE SLIGHTLY BY TUES/WED TO 6 TO 6.5 C/KM...SO AFTERNOON HEATING AND INSTABILITY MAY BE ALL THAT IS NECESSARY FOR SCATTERED CELL DEVELOPMENT EACH DAY. A BOUNDARY WILL FINALLY PUSH INTO THE AREA BY THURS/FRI DAY 7/8 /PER THE LATEST GFS MODEL RUN/. THIS WILL BRING A MORE WIDESPREAD CHANCE FOR RAIN AND THUNDERSTORMS ACROSS THE AREA. HOWEVER...THERE IS QUITE A BIT OF DISAGREEMENT IN THE EXTENDED MODELS THIS FAR OUT...SO DECIDED TO LEAN ON THE ALLBLEND FOR POPS AT THIS TIME. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 810 AM EDT FRI AUG 22 2014 PATCHY IFR OR WORSE FOG WILL LIFT AND DISSIPATE BY AROUND 13Z THIS MORNING. CONVECTION WILL THREATEN ONCE AGAIN THIS AFTERNOON...WITH LOCATIONS ALONG AND NORTHEAST OF A LINE FROM KIOB TO KJKL TO KI35 SEEING THE BETTER CHANCE OF MORE SUSTAINED CONVECTION. THE THREAT WILL DIMINISH THIS EVENING...WITH FOG SETTING IN ONCE AGAIN...PARTICULARLY AT ANY LOCATIONS THAT SEE HEAVIER RAINFALL. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...JMW AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1003 AM CDT FRI AUG 22 2014 .UPDATE... ISSUED AT 959 AM CDT FRI AUG 22 2014 ADDED PATCHY DRIZZLE TO THE FORECAST THROUGH THE DAY AND KEPT FOG...LOCALLY DENSE MENTIONED THROUGH THE AFTERNOON AROUND THE TWIN PORTS...ESPECIALLY ALONG THE HILLSIDE AREA. LAKE BREEZE OFF LS WILL CONTINUE TODAY AND INTO THE WEEKEND WITH COOL TEMPERATURES...LOW CLOUDS AND PATCHY FOG AND DZ. REST OF THE FORECAST LOOKS ON TRACK AT THIS TIME. UPDATE ISSUED AT 650 AM CDT FRI AUG 22 2014 UPDATED AVIATION SECTION BELOW. && .SYNOPSIS... ISSUED AT 308 AM CDT FRI AUG 22 2014 MID LVL RIDGING CONTINUES OVER THE CWA EARLY THIS MORNING AS A BROAD AREA OF WEAK LOW PRESSURE SHIFTS SLOW EAST UNDERNEATH. LATEST RUC SHOWS A 925 LOW OVER WCTRL WISC WITH AN INVERTED SHEAR AXIS EXTENDING NORTHWEST TOWARDS KBJI AND KROX. THIS IS FOLLOWED BY A COLD FRONT STRETCHING FROM ERN MANITOBA SOUTH TO CENTRAL SODAK. MAIN STORY OVER CWA THIS MORNING IS TRAPPED MOIST LAYER... ABOUT 5K FT IN DEPTH...UNDERNEATH SUBSIDENCE INVERSION. BR/FG AND EVEN SOME DRIZZLE IS OCCURRING IN MANY AREAS. A FEW CONVECTIVE CELLS HAVE TRIED TO DEVELOP OVER SERN WISC ZONES IN AN AREA OF LOW LVL THETAE RIDGE AXIS. LIMITED INSTABILITY HAS ALLOWED FAIRLY SHORT TEMPORAL NATURE TO DEVELOPMENT. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 TODAY...FCST MDL SNDGS SUGGEST IT MAY TAKE QUITE SOME TIME TO DISSIPATE THE CANOPY OF STRATUS AND BR ACROSS THE REGION. COND PRES DEFICITS SHOW A TREND TO DIMINISHING BR BY 14/15Z....THEN A RELATIVELY SATURATED CLOUD LAYER FINALLY BREAKING AFTER 2PM. PRECIP CHC SEEMS QUITE LIMITED BY RIDGING ALOFT AND LACK OF LOW LVL FOCUS FOR CONVERGENCE. THE GREATEST OPPORTUNITY MAY ARISE IN THE AFTERNOON AHEAD OF APPROACHING FRONTAL BDRY PUSHING TOWARDS NWRN CWA. MID LVL WARMTH WILL LIMIT MUCH DEVELOPMENT UNTIL AFTERNOON AS 70H THERMAL COOLING COMMENCES OVER WRN CWA. TONIGHT...MID LVL RIDGE AMPLIFIES OVERHEAD TONIGHT IN RESPONSE TO UPSTREAM STRENGTHENING OF TROF OVER ROCKIES. FRONTAL BDRY WILL STALL NORTH AND WEST OF CWA HOWEVER ITS ASSOCIATED PREFRONTAL THETAE RIDGE WILL BE NEARBY. ALTHOUGH THE DRY FORECAST WAS CARRIED OVER FROM PREVIOUS FCSTR...WILL NEED TO WATCH FOR SOME DEVELOPMENT OF CONVECTION MAKING IT INTO NWRN CWA TONIGHT. TOMORROW...HEIGHT FALLS MOVE INTO WRN HIGH PLAINS WITH SFC LOW ORGANIZING OVER SODAK. A SWRLY MID LVL FLOW WILL BEGIN OVER THE CWA AS THE RIDGE AXIS SHIFTS EAST. SFC HIGH PRESSURE WILL INCREASE OVER LAKE SUPERIOR WITH DISTINCT ONSHORE COMPONENT TO BDRY LYR WIND. TOUGH FCST FOR PRECIP AS MAIN FOCUS APPEARS TO BE SHAPING UP OVER THE WRN CWA BY LATE IN THE DAY. CLOUDS/PRECIP FCST FOR NORTH SHORE BASED ON A COMBINATION OF TERRAIN LIFT AND A GRADUAL DEEPENING OF SYNOPTIC SCALE MOIST LAYER. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 THE STRONG SURFACE LOW WILL MOVE NORTH ALONG THE WESTERN MINNESOTA BORDER SATURDAY NIGHT AND SUNDAY MORNING...BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...MAINLY THE THE WESTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. HAVE GONE AHEAD AN INCREASED POPS TO CATEGORICAL THERE...WITH HIGH END CHANCE TO LIKELY POPS ELSEWHERE AS THE WARM FRONT MOVES NORTH ACROSS THE REGION. MODELS ARE GETTING CLOSE ENOUGH TOGETHER TO HAVE A FAIRLY HIGH CONFIDENCE...THOUGH THE TRACK IS STILL SOMEWHAT PROBLEMATIC. WITH THE SURFACE LOW MOVING NORTHEAST OF THE REGION SUNDAY AND SUNDAY NIGHT....A COLD FRONT IS DRAGGED THROUGH THE AREA. DEPENDING ON THE MODEL...THE TIMING DIFFERS...BUT EITHER WAY WE ARE LOOKING AT MORE CHANCE TO LIKELY POPS. THE ECMWF...WHICH IS FARTHER WEST THAN THE GFS IMPLIES WE MAY HAVE SOME POTENTIAL FOR SEVERE STORMS...AS THE FRONT COMES THROUGH LATER AND ALLOWS FOR HEATING DURING THE DAY TO BUILD INSTABILITY AHEAD OF IT. WILL HAVE TO WATCH THIS CAREFULLY IN THE NEXT FEW DAYS. HAVE GONE WITH SOME FAIRLY WARM HIGH TEMPS ON SUNDAY...BUT IF THE ECMWF WORKS OUT...THESE WILL NEED TO BE RAISED. THIS STORM LINGERS OVER WESTERN ONTARIO FOR MONDAY BEFORE MOVING OFF TO THE NORTHEAST MONDAY AFTERNOON AND NIGHT...KEEPING SOME CHANCE POPS GOING OVER THE AREA BOTH PERIODS WITH COOLER TEMPERATURES. OUR NEXT SIGNIFICANT STORM SYSTEM COMES BY ON TUESDAY THROUGH WEDNESDAY. MODELS ARE VARYING SIGNIFICANTLY BY THIS POINT...WITH THE THE GFS BRINGING AN AREA OF MODERATE TO HEAVY RAIN ACROSS THE FORECAST AREA...AND THE ECMWF KEEPING IT FARTHER SOUTH AND DRIER FOR US. FOR NOW HAVE GONE WITH A BLEND APPROACH WITH SOME CHANCE POPS AND WE WILL HAVE TO REVISIT WITH LATER FORECASTS. A STRONG SURFACE RIDGE BUILDS INTO THE AREA FOR WEDNESDAY NIGHT AND THURSDAY....BRINGING COOLER TEMPERATURES AND HOPEFULLY A BIT MORE SUNSHINE TO THE REGION. LOWS BY WEDNESDAY NIGHT AND THURSDAY NIGHT MAY DIP INTO THE 40S AGAIN FOR PORTIONS OF THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 650 AM CDT FRI AUG 22 2014 WIDE RANGE OF CONDITIONS ACROSS THE TERMINALS THIS MORNING...WITH LIFR FOR KDLH...KHYR AND KBRD WHERE NORTHEAST FLOW OFF LAKE SUPERIOR HAS GENERATED STRATUS AND EVEN SOME LIFR VISIBILITIES IN FOG. KHIB IS IFR WITH KINL AT VFR CIGS...THOUGH VFR VISIBILITIES BOTH LOCATIONS. CIGS AND VISIBILITIES EXPECTED TO GRADUALLY IMPROVE THROUGH 20Z TODAY...WITH MOST TERMINALS RETURNING TO AT LEAST MVFR CIGS AND VFR VISIBILITIES. THIS EVENING CIGS AND VISIBILITIES TO DETERIORATE AGAIN AFTER 02Z...LIKELY DROPPING TO IFR/LIFR CIGS AND VISIBILITIES FOR SEVERAL HOURS OVERNIGHT. && .PRELIMINARY POINT TEMPS/POPS... DLH 68 60 70 61 / 30 10 20 60 INL 74 57 76 58 / 20 10 30 70 BRD 78 61 75 64 / 10 20 50 70 HYR 76 61 78 64 / 20 20 40 60 ASX 71 59 73 62 / 30 20 20 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR MNZ037. WI...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR WIZ001. LS...NONE. && $$ UPDATE...BJT SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...LE AVIATION...LE
AREA FORECAST DISCUSSION
NWS DULUTH MN
650 AM CDT FRI AUG 22 2014 .UPDATE... ISSUED AT 650 AM CDT FRI AUG 22 2014 UPDATED AVIATION SECTION BELOW. && .SYNOPSIS... ISSUED AT 308 AM CDT FRI AUG 22 2014 MID LVL RIDGING CONTINUES OVER THE CWA EARLY THIS MORNING AS A BROAD AREA OF WEAK LOW PRESSURE SHIFTS SLOW EAST UNDERNEATH. LATEST RUC SHOWS A 925 LOW OVER WCTRL WISC WITH AN INVERTED SHEAR AXIS EXTENDING NORTHWEST TOWARDS KBJI AND KROX. THIS IS FOLLOWED BY A COLD FRONT STRETCHING FROM ERN MANITOBA SOUTH TO CENTRAL SODAK. MAIN STORY OVER CWA THIS MORNING IS TRAPPED MOIST LAYER... ABOUT 5K FT IN DEPTH...UNDERNEATH SUBSIDENCE INVERSION. BR/FG AND EVEN SOME DRIZZLE IS OCCURRING IN MANY AREAS. A FEW CONVECTIVE CELLS HAVE TRIED TO DEVELOP OVER SERN WISC ZONES IN AN AREA OF LOW LVL THETAE RIDGE AXIS. LIMITED INSTABILITY HAS ALLOWED FAIRLY SHORT TEMPORAL NATURE TO DEVELOPMENT. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 TODAY...FCST MDL SNDGS SUGGEST IT MAY TAKE QUITE SOME TIME TO DISSIPATE THE CANOPY OF STRATUS AND BR ACROSS THE REGION. COND PRES DEFICITS SHOW A TREND TO DIMINISHING BR BY 14/15Z....THEN A RELATIVELY SATURATED CLOUD LAYER FINALLY BREAKING AFTER 2PM. PRECIP CHC SEEMS QUITE LIMITED BY RIDGING ALOFT AND LACK OF LOW LVL FOCUS FOR CONVERGENCE. THE GREATEST OPPORTUNITY MAY ARISE IN THE AFTERNOON AHEAD OF APPROACHING FRONTAL BDRY PUSHING TOWARDS NWRN CWA. MID LVL WARMTH WILL LIMIT MUCH DEVELOPMENT UNTIL AFTERNOON AS 70H THERMAL COOLING COMMENCES OVER WRN CWA. TONIGHT...MID LVL RIDGE AMPLIFIES OVERHEAD TONIGHT IN RESPONSE TO UPSTREAM STRENGTHENING OF TROF OVER ROCKIES. FRONTAL BDRY WILL STALL NORTH AND WEST OF CWA HOWEVER ITS ASSOCIATED PREFRONTAL THETAE RIDGE WILL BE NEARBY. ALTHOUGH THE DRY FORECAST WAS CARRIED OVER FROM PREVIOUS FCSTR...WILL NEED TO WATCH FOR SOME DEVELOPMENT OF CONVECTION MAKING IT INTO NWRN CWA TONIGHT. TOMORROW...HEIGHT FALLS MOVE INTO WRN HIGH PLAINS WITH SFC LOW ORGANIZING OVER SODAK. A SWRLY MID LVL FLOW WILL BEGIN OVER THE CWA AS THE RIDGE AXIS SHIFTS EAST. SFC HIGH PRESSURE WILL INCREASE OVER LAKE SUPERIOR WITH DISTINCT ONSHORE COMPONENT TO BDRY LYR WIND. TOUGH FCST FOR PRECIP AS MAIN FOCUS APPEARS TO BE SHAPING UP OVER THE WRN CWA BY LATE IN THE DAY. CLOUDS/PRECIP FCST FOR NORTH SHORE BASED ON A COMBINATION OF TERRAIN LIFT AND A GRADUAL DEEPENING OF SYNOPTIC SCALE MOIST LAYER. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 THE STRONG SURFACE LOW WILL MOVE NORTH ALONG THE WESTERN MINNESOTA BORDER SATURDAY NIGHT AND SUNDAY MORNING...BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...MAINLY THE THE WESTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. HAVE GONE AHEAD AN INCREASED POPS TO CATEGORICAL THERE...WITH HIGH END CHANCE TO LIKELY POPS ELSEWHERE AS THE WARM FRONT MOVES NORTH ACROSS THE REGION. MODELS ARE GETTING CLOSE ENOUGH TOGETHER TO HAVE A FAIRLY HIGH CONFIDENCE...THOUGH THE TRACK IS STILL SOMEWHAT PROBLEMATIC. WITH THE SURFACE LOW MOVING NORTHEAST OF THE REGION SUNDAY AND SUNDAY NIGHT....A COLD FRONT IS DRAGGED THROUGH THE AREA. DEPENDING ON THE MODEL...THE TIMING DIFFERS...BUT EITHER WAY WE ARE LOOKING AT MORE CHANCE TO LIKELY POPS. THE ECMWF...WHICH IS FARTHER WEST THAN THE GFS IMPLIES WE MAY HAVE SOME POTENTIAL FOR SEVERE STORMS...AS THE FRONT COMES THROUGH LATER AND ALLOWS FOR HEATING DURING THE DAY TO BUILD INSTABILITY AHEAD OF IT. WILL HAVE TO WATCH THIS CAREFULLY IN THE NEXT FEW DAYS. HAVE GONE WITH SOME FAIRLY WARM HIGH TEMPS ON SUNDAY...BUT IF THE ECMWF WORKS OUT...THESE WILL NEED TO BE RAISED. THIS STORM LINGERS OVER WESTERN ONTARIO FOR MONDAY BEFORE MOVING OFF TO THE NORTHEAST MONDAY AFTERNOON AND NIGHT...KEEPING SOME CHANCE POPS GOING OVER THE AREA BOTH PERIODS WITH COOLER TEMPERATURES. OUR NEXT SIGNIFICANT STORM SYSTEM COMES BY ON TUESDAY THROUGH WEDNESDAY. MODELS ARE VARYING SIGNIFICANTLY BY THIS POINT...WITH THE THE GFS BRINGING AN AREA OF MODERATE TO HEAVY RAIN ACROSS THE FORECAST AREA...AND THE ECMWF KEEPING IT FARTHER SOUTH AND DRIER FOR US. FOR NOW HAVE GONE WITH A BLEND APPROACH WITH SOME CHANCE POPS AND WE WILL HAVE TO REVISIT WITH LATER FORECASTS. A STRONG SURFACE RIDGE BUILDS INTO THE AREA FOR WEDNESDAY NIGHT AND THURSDAY....BRINGING COOLER TEMPERATURES AND HOPEFULLY A BIT MORE SUNSHINE TO THE REGION. LOWS BY WEDNESDAY NIGHT AND THURSDAY NIGHT MAY DIP INTO THE 40S AGAIN FOR PORTIONS OF THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 650 AM CDT FRI AUG 22 2014 WIDE RANGE OF CONDITIONS ACROSS THE TERMINALS THIS MORNING...WITH LIFR FOR KDLH...KHYR AND KBRD WHERE NORTHEAST FLOW OFF LAKE SUPERIOR HAS GENERATED STRATUS AND EVEN SOME LIFR VISIBILITIES IN FOG. KHIB IS IFR WITH KINL AT VFR CIGS...THOUGH VFR VISIBILITIES BOTH LOCATIONS. CIGS AND VISIBILITIES EXPECTED TO GRADUALLY IMPROVE THROUGH 20Z TODAY...WITH MOST TERMINALS RETURNING TO AT LEAST MVFR CIGS AND VFR VISIBILITIES. THIS EVENING CIGS AND VISIBILITIES TO DETERIORATE AGAIN AFTER 02Z...LIKELY DROPPING TO IFR/LIFR CIGS AND VISIBILITIES FOR SEVERAL HOURS OVERNIGHT. && .PRELIMINARY POINT TEMPS/POPS... DLH 71 60 70 61 / 20 10 20 60 INL 76 56 76 58 / 30 10 30 70 BRD 79 61 75 64 / 10 10 50 70 HYR 80 61 78 64 / 20 10 40 60 ASX 71 59 73 62 / 20 10 20 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MNZ037. WI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR WIZ001. LS...NONE. && $$ UPDATE...LE SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...LE AVIATION...LE
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
626 AM CDT Fri Aug 22 2014 .SHORT TERM: (Through Sunday) Issued at 312 AM CDT Fri Aug 22 2014 Well it finally feels like summer. Heat index values yesterday afternoon topped out around 105 degrees in the immediate St. Louis Metropolitan Area where the EXCESSIVE HEAT WARNING remains in effect until Sunday evening. Elsewhere, heat indices remained within the 100 to 104 degree range, including locations across northeast Missouri and west central Illinois. Will be adding the northeast Missouri and west central Illinois counties to the HEAT ADVISORY to account for heat index values reaching longevity criteria of 100 degree heat index for four or more days. I expect that the longevity of the heat wave (now likely extending into next week) will lead to future extensions in time as confidence increases. Have introduced some low chance POPs for thunderstorms this afternoon and evening across the northern half of the CWA. Hard to ignore mesoscale model guidance suggesting a secondary warm front developing across the northern CWA by this evening as low pressure deepens across the Central Plains. Both 00Z 4KM NCEP and NSSL WRF runs depict an active late afternoon and evening across the northern CWA - with the potential for an outflow to move south toward I-70. Again, for now, I have only increased POPs so that there is a mention in the forecast. Day shift will have to reevaluate as HRRR and RAP comes into range later this morning. CVKING .LONG TERM: (Monday through Thursday) Issued at 312 AM CDT Fri Aug 22 2014 Hot and dry conditions extend into next week ahead of a cold front that is now forecast to arrive on Wednesday. This front should bring a chance of rain and utlimately cooler temperatures by Thursday. CVKING && .AVIATION: (For the 12z TAFs through 12z Saturday Morning) Issued at 626 AM CDT Fri Aug 22 2014 Complex of storms moving east across northern Missouri as of 11z. For now have added vcts mention at KUIN through 15z. Otherwise, rest of taf sites to remain dry with vfr conditions and light winds picking up from the southwest this morning. Then winds to become light and variable once again this evening. KUIN continues to be on southern perifery of storm activity, so added vcts mention after 01z Saturday. Specifics for KSTL: Metro area to remain dry with vfr conditions and light winds picking up from the southwest this morning. Then winds to become light and variable once again by 01z Saturday. Byrd && .LSX WATCHES/WARNINGS/ADVISORIES: MO...HEAT ADVISORY until 7 PM CDT Sunday FOR Audrain MO-Boone MO- Callaway MO-Cole MO-Franklin MO-Gasconade MO-Jefferson MO- Knox MO-Lewis MO-Lincoln MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby MO-St. Charles MO-St. Francois MO-Ste. Genevieve MO-Warren MO. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR St. Louis City MO-St. Louis MO. IL...HEAT ADVISORY until 7 PM CDT Sunday FOR Adams IL-Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL- Macoupin IL-Marion IL-Monroe IL-Montgomery IL-Pike IL- Randolph IL-Washington IL. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR Madison IL-St. Clair IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
625 AM EDT FRI AUG 22 2014 .SYNOPSIS... ROUNDS OF SHOWERS AND THUNDERSTORMS CONTINUE WITH OCCASIONAL DOWNPOURS...AS WEAK DISTURBANCES RIDE SE. HIGH PRESSURE WILL TRY TO NOSE IN FROM THE NORTHEAST EARLY NEXT WEEK AS UPPER RIDGE BUILDS. && .NEAR TERM /THROUGH TONIGHT/... UPDATE AT 625 AM...THOUGHT FOR A MOMEMT THERE MAY BE A GAP WITH NO SHOWERS...BETWEEN THE LARGER CLUSTERS OF CONVECTION THIS MORNING. THEN NEW SMALL CELLS FORM VCNTY CRW ON INTO SE OHIO AROUND 10Z. WILL BE A BIT FASTER BRINGING NEXT LKLY POP INTO SE OHIO THIS MORNING. THE REST IS FROM THE 415 AM DISCUSSION... ENTERING INTO THE PEAK OF THE FLASH FLOOD CONCERN - NOW INTO TONIGHT. BEST LOW LEVEL INFLOW AT 925 MB IS ONGOING WITH 20 TO 30 KNOT UNDISTURBED FEED UP THE OHIO VALLEY AND INTO THE WNW TO ESE BAROCLINIC ZONE. 925 MB REDUCES TO 10 TO 15 KNOTS AFTER 18Z TODAY. SEVERAL SMALL MID LEVEL 500 MB VORT MAXIMUMS IN THE NW FLOW ALOFT. ONE PASSES CROSSES SRN WV MOUNTAINS AROUND 12Z. 07Z RAP HAS ANOTHER ALONG INDIANA/OHIO BORDER BY THEN. HOWEVER...EVEN AT 08Z...MORE STORMS HAVE REACHED INTO WESTERN OHIO. SO...DOING HOURLY POPS WAS CERTAINLY A CHALLENGE ON THIS GRAVEYARD SHIFT. EVEN THOUGH THE PKB-CKB AREA DID NOT GET MUCH RAIN ON THURSDAY...MOST COUNTIES HAVE BEEN AFFECTED PAST WEEK. DID NOT WANT TO OVER FORECAST WHERE EACH CLUSTER OF STORMS MAY GO AND TRY TO NARROW DOWN THE WATCH. POSTED A FLASH FLOOD WATCH FOR ENTIRE CWA THROUGH 05Z SATURDAY. STILL SEEMS THE HEART OF THE CWA MOST VULNERABLE. EVEN THE 07Z RAP HAS THE AXIS OF MAXIMUM PW FM NRN IL ESE INTO CENTRAL WV AOA 2 INCHES. HOWEVER...THE SOUTHERN COAL FIELDS HAVE BEEN THE WETTEST LATELY AND WOULD HAVE THE HIGHEST RUNOFF PERCENTAGE. STEERING FLOW TURNS MORE NORTH OVERNIGHT TONIGHT...SO PICTURING THE TREND WILL BE FOR THE HIGHER POPS TO SINK INTO SOUTHERN COUNTIES OVERNIGHT. THOUGH AS MENTIONED...LOW LEVEL INFLOW...AS MENTIONED...NOT AS STRONG. IN THIS PATTERN...COULD EVEN SEE STRONG RISES ON SOME HEADWATER RIVERS TONIGHT INTO SATURDAY. && .SHORT TERM /SATURDAY THROUGH MONDAY/... BOUNDARY CONTINUES SINKING SOUTH SATURDAY...BUT STILL ENOUGH MOISTURE AROUND TO KICK OFF SOME DIURNALLY DRIVEN SHOWERS AND STORMS...MAINLY IN THE COAL FIELDS AND WV MOUNTAINS. PRECIP CHANCES WILL GRADUALLY DECREASE NORTH TO SOUTH THROUGH THE WEEKEND...EVENTUALLY DRYING OUT ACROSS THE NORTH AS HEIGHTS BUILD AND A SURFACE HIGH NOSES IN FROM THE NE BY SUNDAY NIGHT. DESPITE THE BOUNDARY HEADING SOUTH...STILL EXPECTING VERY WARM TEMPERATURES. MADE ONLY MINIMAL CHANGES TO PREVIOUS HIGHS AND LOWS BY BLENDING IN BIAS-CORRECTED CONSENSUS GUIDANCE. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... UPPER RIDGE CONTINUES TO BUILD INTO AREA BUT THE OPPRESSIVE HEAT SHOULD STAY W OF THE AREA. HOWEVER...WE WILL STILL BE CONTENDING WITH THE MUGGIES WITH TEMPS RUNNING NEAR NORMAL TO PERHAPS SLIGHTLY ABOVE. A FRONT APPROACHES LONG ABOUT THURSDAY WITH INCREASING CHANCES FOR SHRA/TSRA. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... ONE ROUNDS OF CONVECTION MOVES THROUGH 06Z TO 12Z WITH LOCALIZED DOWNPOURS AND IFR VSBY AND CEILING. OTHER DISTURBANCES IN ITS WAKE WILL RIDE SE AND MAY CAUSE ADDITIONAL CLUSTERS DURING THE MORNING...FIGURING MORE IN SOUTHERN OHIO INTO WESTERN WEST VIRGINIA FOR THE 12Z TO 15Z TIME FRAME...BUT CONFIDENCE IS LOW. CEILINGS BECOMING MAINLY 2 TO 3 THSD FT BKN WITH LAYERS AND VSBY 5 TO 6 MILES IN HAZE AFTER ABOUT 16Z. YET...ADDITIONAL CLUSTERS OF SHOWERS AND STORMS LIKELY...INTO THE EVENING HOURS...AGAIN WITH IFR VSBY AND CEILINGS. MVFR VSBY LIKELY 03Z TO 06Z SATURDAY WITH SHOWERS WANING. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: DURATION AND TIMING ROUNDS OF CONVECTION WILL VARY. AT LEAST SOME AREAS OF PCPN MAY EVEN LINGER LONGER FRIDAY NIGHT...BUT NOT MENTIONED IN TAFS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18 CRW CONSISTENCY H H H M M M M M M M M M HTS CONSISTENCY H H H M M M M M M M M M BKW CONSISTENCY M M M M H H H H H H M M EKN CONSISTENCY H H H H H H M M H H M H PKB CONSISTENCY L L L H H H H H M M M M CKB CONSISTENCY M M M H H H H H H H M M AFTER 12Z SATURDAY... IFR CONDITIONS POSSIBLE IN LOW STRATUS IN LINGERING LOW LEVEL MOISTURE 06Z TO AFTER 12Z SATURDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WVZ005>011-013>020- 024>040-046-047. OH...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OHZ066-067-075-076- 083>087. KY...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR KYZ101>103-105. VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ003-004. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...30 AVIATION...KTB
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
627 AM CDT FRI AUG 22 2014 .AVIATION... SIMILAR TO THE PAST FEW DAYS...THUNDERSTORMS WILL LIKELY DEVELOP WEST OF KLBB LATE THIS AFTERNOON INTO THE EVENING. HOWEVER...CONFIDENCE IS NOT HIGH IN STORMS REACHING THE KLBB TERMINAL AND WILL LEAVE ANY MENTION OF THUNDER OUT UNTIL BETTER CONFIDENCE CAN BE ACHIEVED. && .PREV DISCUSSION... /ISSUED 421 AM CDT FRI AUG 22 2014/ SHORT TERM... AFTERNOON AND EVENING THUNDERSTORM CHANCES WILL LIVE ANOTHER DAY. A CLOSED LOW CURRENTLY OVER ARIZONA WILL OPEN UP AS IT MOVES ACROSS THE ROCKIES AS A SHORT WAVE TROUGH. HOWEVER...IT REMAINS QUESTIONABLE ON WHETHER WE WILL BENEFIT FROM THIS TROUGH AS ITS JET MAX WILL BE PLACED WELL NORTH AND WEST OF THE REGION. WE STILL STILL LIKELY SEE ISOLATED TO SCATTERED CONVECTION UNDERNEATH A MONSOONAL MOISTURE PLUME CAUGHT BETWEEN THE TROUGH TO THE WEST AND RIDGE TO THE EAST. CONVENTION WILL BE WITHIN THE SURFACE PRESSURE TROUGH AND THE RAP INDICATES A FARTHER EASTWARD MOVEMENT TO THE TROUGH AXIS. LOW LEVEL CONVERGENCE MAY BE MORE TO THE EAST IF THE RAP IS MORE CORRECT IN ITS SOLUTION ALLOWING FOR CONVECTION TO DEVELOP FARTHER EAST ON THE CAPROCK. A NOTABLE DECREASE IN PRECIPITABLE WATER VALUES WILL OCCUR TODAY MOSTLY FOR AREAS EAST OF THE I27 CORRIDOR. THIS WILL BE DUE TO DRIER AIR ADVECTING INTO THE AREA AT MID LEVELS. THERE WILL NOT BE MUCH CHANGE FOR AREAS WEST OF I27 WITH CONTINUED ANOMALOUSLY HIGH PRECIPITABLE WATER VALUES. AN AXIS OF HIGHER INSTABILITY IS PROGGED TO BE AROUND 2000 J/KG WITHIN THE PRESSURE TROUGH WHERE THE HIGHEST LOW LEVEL THETA-E AIR WILL BE LOCATED. FURTHERMORE...STORM PROPAGATION VECTORS TO THE SOUTHWEST WILL LEAD TO POSSIBLE TRAINING OF CONVECTION AND REPEATED HEAVY RAINFALL DESPITE RELATIVELY HIGH CLOUD BASES. LONG TERM... A THINNING BAND OF MONSOONAL MOISTURE WILL CONTINUE ACROSS THE AREA OVER THE WEEKEND AS AN UPPER TROUGH SKIRTS BY TO THE NORTH. LIMITED IF ANY SIGNIFICANT LIFT IS EXPECTED THOUGH MODEST SURFACE TROUGHING AND STRONG HEATING MAY CONTRIBUTE TO A FEW AFTERNOON STORMS IN AND NEAR THAT TROUGH. HEIGHTS WILL REBUILD EARLY NEXT WEEK WITH THE MONSOON FLOW IMPROVING AGAIN...THOUGH SHIFTING BACK TO THE WEST. UNCLEAR JUST YET IF THIS WILL REMAIN NEAR ENOUGH OUR WESTERN BORDER AREAS FOR MENTIONABLE THUNDER CHANCES. UNCERTAINTY INCREASES THE MIDDLE OF NEXT WEEK INVOLVING THE NEXT PROGRESSIVE PACIFIC TROUGH CROSSING THE NORTHERN TIER. BOTH AMPLITUDE AND TIMING ARE MUCH IN QUESTION...THUS PRECLUDING THUNDER MENTION AS WELL FOR NOW. BUT THIS MAY YET REPRESENT OUR NEXT REAL OPPORTUNITY FOR THUNDERSTORMS AS A FRONTAL BOUNDARY THAT HAS BEEN HANGING ACROSS NORTHERN STATES COULD SAG INTO OUR AREA. IN THE DAYS AHEAD WE WILL WATCH FOR THOSE TIMING AND STRENGTH ISSUES TO BECOME BETTER RESOLVED. RMCQUEEN && .PRELIMINARY POINT TEMPS/POPS... FRIONA 92 64 93 62 92 / 30 40 20 20 20 TULIA 94 65 95 65 93 / 20 20 20 20 20 PLAINVIEW 93 65 94 65 92 / 20 20 20 20 20 LEVELLAND 94 64 93 64 92 / 20 20 20 20 20 LUBBOCK 95 67 96 67 94 / 20 20 20 20 20 DENVER CITY 94 65 94 65 93 / 20 20 10 10 10 BROWNFIELD 95 65 95 66 94 / 20 20 10 10 10 CHILDRESS 100 70 100 72 99 / 10 10 10 10 10 SPUR 97 68 97 67 96 / 10 10 10 10 10 ASPERMONT 99 71 100 71 99 / 0 0 10 10 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 01
AREA FORECAST DISCUSSION
NWS SEATTLE WA
905 AM PDT FRI AUG 22 2014 .SYNOPSIS...AN UNSTABLE AIR MASS ASSOCIATED WITH AN UPPER LOW OVER THE INTERIOR OF THE PACIFIC NORTHWEST WILL GENERATE AND CIRCULATE A FEW SHOWERS AND LATE DAY THUNDERSTORMS OVER THE CASCADES TODAY. OTHERWISE HIGHER PRESSURE ALOFT WILL NOSE INTO THE REGION THIS WEEKEND FOR MORE SUNSHINE AND WARMER DAYTIME TEMPERATURES. THIS WARMING TREND IS EXPECTED TO CONTINUE INTO THE MIDDLE OF NEXT WEEK. && .SHORT TERM...IN THE BIG PICTURE THE UPPER RIDGE IS NOW NEAR 140W WITH THE UPSTREAM UPPER TROUGH NEAR THE DATELINE. THE SHORTWAVE THAT WAS DIGGING DOWN THE EAST SIDE OF THE UPPER RIDGE HAS NOW SLID SE INTO THE PACIFIC NW INTERIOR. RAOBS AT KUIL, KOTX AND KSLE THIS MORNING SHOW THE AIR MASS IS QUITE UNSTABLE. SO THE CONTINUED THREAT OF CONVECTION OVER THE CASCADES LATER TODAY LOOKS ON TRACK. THE BULK OF CONVECTION SHOULD BE EAST OF THE CASCADES THOUGH. LOW LEVEL ONSHORE FLOW CONTINUES THIS MORNING THOUGH WEAKER THAN THURSDAY. THE MORE UNSTABLE AIR MASS RESULTED IN MORE LIMITED MARINE CLOUDS IN WESTERN WA THIS MORNING. TOPS ARE SHALLOW - NO MORE THAN 1500 FT. SO THE CLOUDS AND FOG SHOULD DISSIPATE BY MIDDAY. TODAY WILL MARK THE GRADUAL REBOUND OF DAYTIME TEMPERATURES WITH MORE SUNSHINE AND A WARMER AIR MASS. THE 12Z PROGS IN THUS FAR CONTINUE THE TREND OF NOSING IN HIGHER PRESSURE ALOFT AS THE UPPER LOW CONTINUES FURTHER INLAND AND HEIGHTS ALOFT RISE. ANOTHER VERY WEAK SHORTWAVE IS SET TO SLIDE SE INTO THE NORTHERN ROCKIES SUNDAY IN THE NW FLOW ALOFT. THE PRIMARY IMPACT SHOULD BE TO SLOW THE WARM UP AND KEEP LOW LEVEL ONSHORE FLOW GOING. NO UPDATES TO THE FORECAST PACKAGE THOUGH DID MASSAGE THE SKY GRIDS A BIT FOR TODAY AND THIS EVENING. BUEHNER .LONG TERM...FROM THE PREVIOUS DISCUSSION...AN UPPER RIDGE WILL PREVAIL OVER THE REGION DURING THIS PERIOD...HOWEVER IT WILL GRADUALLY WEAKEN WITH TIME. IN FACT...THE LATEST GFS SOLUTION SHOWED AN UPPER TROF OVER THE PACIFIC NORTHWEST ON DAY 7. THE INHERITED FORECAST SHOWED TEMPS COOLING OFF LATE IN THE PERIOD AND THAT LOOKS FINE. NC && .AVIATION...A WEAK UPPER LEVEL TROUGH OVER THE AREA THIS MORNING WILL SHIFT SOUTHEAST INTO SOUTHERN IDAHO BY SATURDAY MORNING. LIGHT NORTHERLY FLOW ALOFT WILL BECOME NORTHWESTERLY AS THE LOW MOVES SOUTHEAST. LOW LEVEL FLOW WILL REMAIN ONSHORE AND WEAK. MARINE STRATUS THAT FORMED THIS MORNING OVER THE COAST...SOUTHWEST INTERIOR...STRAIT AND WESTERN SKAGIT/SNOHOMISH COUNTIES REMAINS SHALLOW WITH CEILINGS BELOW 1000 FEET AND LOCAL VISIBILITIES BELOW A MILE. LIGHT NORTHERLY SURFACE GRADIENTS HELPED LIMIT THE EXTENT OF THE LOW CLOUDS OVER THE INTERIOR...WITH MUCH OF THE CENTRAL SOUND AND WESTERN WHATCOM COUNTY REMAINING CLEAR. THOSE AREAS WITH LOW CLOUDS AND FOG WILL SEE CEILINGS AND CONDITIONS IMPROVE THROUGH THE MORNING...SCATTERING OUT OVER THE INTERIOR BY 18Z/11 AM AND THE COAST BY 20Z/1 PM. WARMING AND WITH THE NORTHERLY FLOW BOTH ALOFT AND AT LOW LEVELS TODAY WILL MAKE IT MORE DIFFICULT FOR LOW CLOUDS AND OR STRATUS TO REFORM OVER THE INTERIOR SATURDAY MORNING. KSEA...MOSTLY CLEAR SKIES TODAY WITH VFR CONDITIONS PERSISTING THROUGH SATURDAY. LIGHT WINDS WILL BECOME NORTHWESTERLY 4 TO 8 KNOTS BY EARLY AFTERNOON AND PERSIST THROUGH THE EVENING...THEN BECOME LIGHT AND NORTHEASTERLY AFTER 06Z/11 PM. && .MARINE...THE VERY PERSISTENT ONSHORE FLOW PATTERN WILL CONTINUE FOR THE NEXT SEVERAL DAYS. THE STRENGTH OF THE ONSHORE FLOW WILL VARY DIURNALLY. EXPECT THE STRONGEST WESTERLY WINDS IN THE CENTRAL AND EASTERN STRAIT DURING THE EVENING AND EARLY MORNING HOURS WITH SMALL CRAFT ADVISORIES POSSIBLE AT THAT TIME EACH DAY INTO THE FIRST PART OF NEXT WEEK. OVER THE COASTAL WATERS SURFACE HIGH PRESSURE BUILDING INSIDE OF 140 W WILL TIGHTEN UP SURFACE GRADIENTS SATURDAY EVENING OVER THE OUTER COASTAL WATERS...BOOSTING THE NORTHWESTERLIES ABOVE SMALL CRAFT CRITERIA. WEST TO NORTHWESTERLY SWELL 4 TO 5 FEET WITH A PERIOD AROUND 8 SECONDS WILL PERSIST THROUGH THE WEEKEND. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...NONE. PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA TONIGHT. && $$ WWW.WEATHER.GOV/SEATTLE/ FOR THE GRAPHICAL AFD...VISIT WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
  [top] Area Forecast Discussion National Weather Service Spokane WA 536 AM PDT FRI AUG 22 2014 .SYNOPSIS... Friday will bring another round of showers and thunderstorms to the region with the potential for more flash flooding over the Cascades burn scars. The threat of scattered showers and thunderstorms will continue through the weekend. A drier and warmer weather pattern is expected for the new work week. && .DISCUSSION... Friday: A deep upper-level low pressure system will pass through the region today delivering widely scattered showers and thunderstorms. Storms containing heavy rainfall and very little movement will be the main concern as the risk for flash flooding and debris flows remains elevated over the East Slopes and Okanogan Highlands. Additional urban and rural areas could also experience localized flooding impacts if a storm was to setup overhead. An isolated stronger storm could also bring brief hail and gusty outflow winds on the order of 40 mph. 2AM satellite reveals the center of the low crossing over the Columbia Gorge near the Dalles. The low will shift east toward the Tri Cities this morning...then continue toward the OR/WA/ID border by midday before tracking into SE Idaho this evening. With the low overhead, an unstable air mass will be in place with 500mb temperatures cooling near -17C. Meanwhile, a tongue of richer moisture and instability...marked well by the 850-700mb theta-e progs will wrap around the eastern and northern periphery of the low...wrapping back south on its western edge. This richer moisture in conjunction with little to no steering flow is a good recipe for storms containing heavy rainfall. The good news is that this lack of steering flow (storm movement) only resides through late afternoon then as the system departs the east, increasing northerly flow will give any lingering storms a push. Needless to say, we saw what these storms are capable of Thursday afternoon with numerous debris flows and mudslides within the Carlton Complex burn scar. As of 2AM...thunderstorms continue to go strong across the northern mountains with additional development now over the lower ID Panhandle. This activity is tied to the placement of the higher theta-E axis and lift along the northeastern periphery of the upper low dropping into the Pac NW. HRRR and local Hi-Res model simulated radar suggest the larger area of showers/storms over Ferry County will pivot to the west this morning, fall apart after sunrise, allowing cells to redevelop after a few hours of sunshine. Convective temperatures are only in the upper 60`s to lower 70`s so it won`t take much. Whether the cloud cover from this activity completely falls apart or just thins will be a major challenge related to storm intensity this afternoon. For NE WA and the ID panhandle, looks as if isolated storms will be possible through morning then afternoon heating and a few vorticity maximums will promote widely scattered storms again after the 12PM-3PM timeframe...continuing through the evening. Slightly deeper wind shear over the lower ID Panhandle could support a few organized cells capable of hail and wind gusts in excess of 40 mph but overall, the threat for severe storms (hail and damaging winds) remains low region-wide. Saturday: The upper-low will continue its march east Friday night and Saturday into Central Montana Saturday morning then North Dakota by the evening. Look for drier north to northwest flow over the Cascades and Western Basin Saturday morning to translate east into the Idaho Panhandle by Saturday evening. The main precipitation threat will concentrate over the ID Panhandle and into Western Montana. Some models are more aggressive with the drying so we may be on the high end for precipitation chances in Idaho, especially west of a line from Mullan to the Blue Mtns. Given the lingering cold pool aloft, a few convective showers will be possible in the mountains all the way to the Cascade Crest but these will be the weak and shallow variety producing little to no rainfall. We will also see breezy northerly winds as the low deepens today then pulls out Saturday. Winds will be strongest through the narrow Okanogan Valley and Purcell Trench. Winds sustained 10-20 mph with gusts to 35 mph are a strong possibility. Temperatures will remain on the cool side of normal. /sb Saturday night through Wednesday...General agreement exists between the latest medium range models with the overall field of motion. The general troffy and unsettled pattern will persist through Sunday featuring a continued threat of showers and at least isolated thunderstorms mainly during the afternoon and evening hours and concentrated over the northern mountains...with a few showers persisting well into the night over the Idaho Panhandle. Temperatures in this polar influenced air mass will run at or slightly below normal through Monday. Monday appears to bring a transition from a general trough to a new ridging cycle...with only a few lingering showers over the northeast and panhandle while the remainder of the forecast area dries out and stabilizes under the ridge driven warming aloft. Tuesday through Wednesday bring high confidence of dry and clear/partly cloudy conditions throughout the region as the polar storm track retreats to the north with temperatures once again cresting well above normal. /Fugazzi Wednesday Evening through Thursday Night: Starting Wednesday evening the strength of the ridge will be on the decline as the next trough of low pressure approaches the region. Models are still wavering a bit on the breakdown, but one thing in common for now is Wednesday will be the warmest day of the forecast period. Considering model differences for the breakdown, the GFS continues to be much more aggressive bringing a deep trough swinging through late Thursday. This solution would support another round of widespread rain as the system would have both mid latitude Pacific moisture as well as topical moisture from decaying Tropical Storm Lowell to work with. The euro on the other hand keeps the trough further north leading to a much drier zonal flow pattern for the Pac NW. Either way, we are looking at breezy to windy conditions for the later part of the week as cold air advection coupled with a tightened pressure gradient increases the winds. Both models have been fairly consistent in their respective solutions, so the DGEX was used to help lean in one models favor. It more closely followed the Euro leading to higher confidence in it. So leaning towards the euro, it delays the major threat of precip beyond the reaches of this forecast so POPs were kept relatively low. Temperatures were also raised a bit Thursday to show the transition to a more zonal pattern rather than the cold incoming trough from the GFS. One thing to keep in mind is that when models try to ingest this tropical storm moisture, it often leads to some inconsistent runs. Knowing this, the extended will need to be tinkered with throughout the next couple of days as models align better. /Fliehman && .AVIATION... 12Z TAFS: Broad area of low pressure aloft will promote widely scattered showers and thunderstorms through 03z. Every terminal will stand a threat for storms, especially after 22z. Ongoing thunderstorms this morning in vcnty KPUW/KLWS are expected to track north by 15z with a brief break before afternoon heating promotes more storms aft 22z. Winds will generally be out of the north/northeast...locally gusty through the Okanogan Valley and Purcell Trench impacting Omak...Sandpoint...and Couer D Alene airports. /sb && .PRELIMINARY POINT TEMPS/POPS... Spokane 75 55 75 54 79 56 / 40 40 10 10 20 30 Coeur d`Alene 73 54 73 51 77 53 / 50 50 10 10 20 30 Pullman 75 51 74 49 79 51 / 40 50 20 20 20 20 Lewiston 80 60 79 56 85 59 / 60 50 30 20 10 20 Colville 72 51 78 49 81 52 / 60 50 10 10 20 30 Sandpoint 69 50 71 46 75 49 / 70 50 10 20 20 30 Kellogg 68 52 67 47 72 53 / 70 60 40 20 30 30 Moses Lake 81 58 83 56 86 58 / 30 50 10 0 10 10 Wenatchee 80 63 82 58 84 64 / 40 50 10 10 20 10 Omak 79 59 82 53 85 58 / 50 40 10 10 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flash Flood Watch through this evening for East Slopes Northern Cascades-Okanogan Valley-Wenatchee Area. && $$
AREA FORECAST DISCUSSION
NWS PORTLAND OR
330 AM PDT FRI AUG 22 2014 .SYNOPSIS...UPPER LEVEL LOW PRESSURE CENTER CONTINUES TO SLIDE EAST OF THE AREA TODAY. THERE WILL BE ENOUGH INSTABILITY ON THE WEST SIDE OF THIS LOW TO BRING A THUNDERSTORM THREAT MAINLY TO THE SOUTH WASHINGTON CASCADES AND...TO A LESSER EXTENT...THE FAR NORTH OREGON CASCADES AS WELL. MAY GET SOME SHOWERS FURTHER WEST ACROSS THE NORTHERN FORECAST AREA ALTHOUGH HAVE WAVERING CONFIDENCE. NORTHERLY FLOW ALOFT CONTINUES OVER THE WEEKEND MAINTAINING ONSHORE LOW-LEVEL FLOW AND NEAR TO SLIGHTLY ABOVE NORMAL HIGH TEMPERATURES. HIGH PRESSURE STRENGTHENS JUST OFFSHORE BRINGING A WARM UP FOR THE FIRST HALF OF NEXT WEEK. && .SHORT TERM...TONIGHT THROUGH SUNDAY...LOW PRESSURE WILL CONTINUE TO DEVELOP ACROSS THE INTERIOR PACNW TODAY RESULTING IN A CHALLENGING FORECAST FOR THE NEXT 24 HOURS. A CLOSED LOW CENTER IS BEGINNING TO WIND UP UNDER CYCLOGENESIS. THE COMPLEX DYNAMICS WITH THE DEVELOPING LOW WERE ABLE TO WRING OUT SOME DRIZZLE ALONG THE COAST WITH BOTH ASTORIA AND NEWPORT RECORDING AT LEAST AN HOUR OF PRECIPITATION. NORTH ANS EAST OF THE DEVELOPING LOW CENTER...A SIGNIFICANT AMOUNT OF NOCTURNAL CONVECTION THUS FAR HAS GENERATED MOISTURE WHICH WILL GET WRAPPED AROUND TO MOISTEN UP THE WESTERN FRINGES OF THE LOW. EXPECT THE NORTHEASTERN 1/3RD OF THE CWA WILL BE IMPACTED BY THIS MOISTURE IN VARYING FORMS. THE MOST SIGNIFICANT THREAT WILL BE FOR THUNDERSTORMS. STILL FEEL MOST ACTIVITY WILL REMAIN CONFINED TO AREAS NORTHEAST OF THE PORTLAND METRO AND CLOSER TO MT ADAMS. BOTH THE NAM AND GFS AGREE THERE WILL BE SUFFICIENT SURFACE HEATING AND MOISTURE TO CREATE DEEP CONVECTION AND THUNDERSTORMS. FURTHER SOUTH AND WEST THE MODELS HAVE LIMITED AGREEMENT. THE BIG ISSUE WILL BE SURFACE DEW POINTS. THE NAM AS OF THE LAST FEW YEARS HAS COMMONLY PRODUCE TOO MUCH SURFACE MOISTURE AND THUS DEW POINTS TOO HIGH BY A FEW DEGREES. CONVERSELY...THE GFS TENDS TO RUN A FEW DEGREES TO DRY. THE 00Z MODEL RUNS ARE HOLDING TRUE TO EXPECTATIONS AT LEAST THROUGH THE 09Z HOUR WITH REALITY LYING SOMEWHERE IN BETWEEN BUT A SLIGHT BIT CLOSER TO THE GFS. DETERMINING WHAT REALITY WILL BRING IS WHERE THE SPECIFIC CHALLENGE LIES. SKIN TEMPERATURES FROM BOTH MODEL FORECAST SOUNDINGS ARE ALSO APPEARING TO BE TOO COOL AS IS OFTEN THE CASE. BASED ON THE RAW MODEL SOUNDING DATA...THE GFS DOES NOT SHOW CONVECTION VERY FAR AWAY FROM THE CASCADES WHILE THE NAM BRINGS A THREAT TO THE METRO AND AS FAR WEST AS ABOUT KELSO/LONGVIEW. ULTIMATELY LANDED ON ABOUT A 60/40 BLEND OF SURFACE DEW POINTS FAVORING THE GFS. THIS COMBINED WITH MANUAL TEMPERATURE ADJUSTMENTS TO THE SOUNDING SURFACE CONDITIONS PRODUCED A FIRST ESTIMATE OF THUNDERSTORMS WITH CONFIDENCE AND ISOLATED COVERAGE ACROSS THE BULK OF SKAMANIA COUNTY...LOWER CONFIDENCE SLIGHT CHANCE COVERAGE TO THE EASTERN 1/4 OF COWLITZ COUNTY STRETCHING SOUTH TO INCLUDE THE GORGE AND AREAS EAST OF SANDY AROUND MT HOOD...AND THEN A THREAT OF SHOWERS ONLY MAINLY NORTH OF THE COLUMBIA RIVER. OBVIOUSLY WE ARE WALKING A VERY FINE LINE TODAY BETWEEN NOTHING HAPPENING ACROSS OUR NORTHERN TIER AND A DECENT COVERAGE OF THUNDERSTORMS SO FELT USING PROBABILITY IN THE TRUEST SENSE WAS THE MOST PRUDENT COURSE OF ACTION TODAY NOTING THAT A 20 PERCENT CHANCE REALLY MEANS 80 PERCENT OF THE TIME IT WILL NOT HAPPEN. DID FEEL REASONABLY CONFIDENT THAT TEMPERATURES NEED TO GET CLOSE TO THEIR FORECASTED HIGHS TODAY TO TRIGGER CONVECTION IN ANY FORM. THUS WOULD NOT EXPECT TO SEE MUCH RAIN FORMING UNTIL AFTER 2 PM. ALSO WOULD NOT EXPECT IT TO LAST VERY LONG INTO THE EVENING BUT DID NOT HAVE AS MUCH CONFIDENCE TO SHUT OFF THE THREAT BY 8 PM SO LEFT IT IN PLACE FOR THE ENTIRE EVENING. THE UPPER LOW WILL SLOWLY MOVE EAST OVERNIGHT WHILE AN UPPER RIDGE BUILDS OFFSHORE. THIS WILL MAINTAIN A TYPICALLY DRIER NORTHWESTERLY TO NORTHERLY FLOW AND BRING UNEVENTFUL WEATHER FOR THE REST OF THE WEEKEND ASIDE FROM CLOUDS AT THE COAST AND PERHAPS SOME BRIEF MORNING CLOUDS INLAND. TEMPERATURES NEAR OR SLIGHTLY ABOVE NORMAL WILL GRADUALLY WARM FURTHER. /JBONK .LONG TERM...SUNDAY THROUGH THURSDAY...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. UPPER LEVEL RIDGING WILL MOVE ONSHORE ALLOWING TEMPERATURES TO INCREASE SLIGHTLY ABOVE SEASONAL NORMS FOR THE BEGINNING PART OF NEXT WEEK. AS THE RIDGE BEGINS TO BREAKDOWN AND BECOME MORE ZONAL WE WILL SEE AN INCREASE IN LOW AND MID LEVEL MOISTURE. THIS WILL PROVIDE FOR AN INCREASE IN CLOUD COVER FOR THE LATTER PART OF NEXT WEEK. DO NOT EXPECT ANY PRECIPITATION IN THE NEAR FUTURE. /64 && .AVIATION...A WEAKENING FRONT CONTINUES TO PUSH ONSHORE THIS MORNING WITH PRIMARILY MVFR CIGS ALONG THE COASTAL AREAS ALONG WITH SOME LIGHT DRIZZLE. SOME SCATTERED CLOUDS BELOW 1000 FT ALONG THE CENTRAL OREGON COAST...SO CANNOT RULE OUT LOCAL IFR AT TIMES THROUGH 18Z. THEREAFTER...EXPECT SCATTERED MID CLOUDS GRADUALLY DIMINISHING FOR THE COAST WITH GUSTY WINDS POSSIBLE IN AFT 21Z S OF KTMK. MEANWHILE...INCREASING MID CLOUDS ACROSS THE INTERIOR THIS MORNING AS FRONT APPROACHES. EXPECT VARIABLE SCATTERED TO BROKEN CLOUDS...TRENDING TOWARDS BROKEN 10Z-18Z BUT REMAINING VFR WITH CLOUD DECK AT OR ABOVE 4500 FT. AFT 20Z...EXPECT CLEARING S OF A KKLS-KPDX-KRDM LINE WITH SCT CLOUDS LINGERING N OF THIS LINE BUT SCATTERING BY LATE AFTERNOON. KPDX AND APPROACHES...VFR NEXT 24 HRS. INCREASING CLOUDS AT OR ABOVE 4500 FT THROUGH 18Z AS WEAK FRONT APPROACHES...THEN INCREASING CLEARING AT TERMINAL THEREAFTER. BKN-OVC DECK AROUND 4000 FT MAY PERSIST OVER EASTERN APPROACHES THROUGH 06Z SAT. CULLEN && .MARINE...A WEAK FRONT HAS PROGRESSED ACROSS THE WATERS EARLY THIS MORNING AND WILL CONTINUE TO SLIDE ONSHORE THIS MORNING. HIGH PRES THEN REBUILDS OVER THE COASTAL WATERS LATER TODAY AND WILL PERSIST OVER THE NE PAC INTO NEXT WEEK. MEANWHILE...A THERMAL TROUGH OVER NORTHERN CALIFORNIA WILL STRENGTHEN...WHICH WILL INCREASE THE SURFACE PRES GRADIENT...PARTICULARLY OVER THE CENTRAL OREGON WATERS. THEREFORE...N-NW WINDS WILL CONTINUE AND WILL BE GUSTY AT TIMES...PARTICULARLY IN THE LATE AFTERNOON AND EVENING HOURS. MAY SEE A FEW GUSTS TO 20 KT S OF CASCADE HEAD TODAY...BUT GRADIENT SHOULD INCREASE SAT WITH WINDS POSSIBLY REACHING ADVISORY CRITERIA. SEAS WILL REMAIN 3 TO 5 FT TODAY...BUT REMAIN RELATIVELY STEEP WITH A DOMINANT PERIOD AROUND 9 SECONDS. SEAS MAY INCREASE THIS WEEKEND TO 5 TO 7 FT...ESPECIALLY IN AREAS WITH STRONGER WINDS WITH A MIX OF WIND WAVE AND FRESH SWELL DOMINATING. STEEP CONDITIONS LIKELY CONTINUE WITH MODELS SUGGESTING PERIODS SHORTENING TO 7-8 SECONDS...SO WILL NEED TO MONITOR FOR POTENTIAL ADVISORY FOR HAZARDOUS SEAS FROM SAT INTO EARLY NEXT WEEK. CULLEN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...NONE. && $$ INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/NWSPORTLAND 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 National Weather Service Spokane WA 232 AM PDT FRI AUG 22 2014 .SYNOPSIS... Friday will bring another round of showers and thunderstorms to the region with the potential for more flash flooding over the Cascades burn scars. The threat of scattered showers and thunderstorms will continue through the weekend. A drier and warmer weather pattern is expected for the new work week. && .DISCUSSION... Friday: A deep upper-level low pressure system will pass through the region today delivering widely scattered showers and thunderstorms. Storms containing heavy rainfall and very little movement will be the main concern as the risk for flash flooding and debris flows remains elevated over the East Slopes and Okanogan Highlands. Additional urban and rural areas could also experience localized flooding impacts if a storm was to setup overhead. An isolated stronger storm could also bring brief hail and gusty outflow winds on the order of 40 mph. 2AM satellite reveals the center of the low crossing over the Columbia Gorge near the Dalles. The low will shift east toward the Tri Cities this morning...then continue toward the OR/WA/ID border by midday before tracking into SE Idaho this evening. With the low overhead, an unstable air mass will be in place with 500mb temperatures cooling near -17C. Meanwhile, a tongue of richer moisture and instability...marked well by the 850-700mb theta-e progs will wrap around the eastern and northern periphery of the low...wrapping back south on its western edge. This richer moisture in conjunction with little to no steering flow is a good recipe for storms containing heavy rainfall. The good news is that this lack of steering flow (storm movement) only resides through late afternoon then as the system departs the east, increasing northerly flow will give any lingering storms a push. Needless to say, we saw what these storms are capable of Thursday afternoon with numerous debris flows and mudslides within the Carlton Complex burn scar. As of 2AM...thunderstorms continue to go strong across the northern mountains with additional development now over the lower ID Panhandle. This activity is tied to the placement of the higher theta-E axis and lift along the northeastern periphery of the upper low dropping into the Pac NW. HRRR and local Hi-Res model simulated radar suggest the larger area of showers/storms over Ferry County will pivot to the west this morning, fall apart after sunrise, allowing cells to redevelop after a few hours of sunshine. Convective temperatures are only in the upper 60`s to lower 70`s so it won`t take much. Whether the cloud cover from this activity completely falls apart or just thins will be a major challenge related to storm intensity this afternoon. For NE WA and the ID panhandle, looks as if isolated storms will be possible through morning then afternoon heating and a few vorticity maximums will promote widely scattered storms again after the 12PM-3PM timeframe...continuing through the evening. Slightly deeper wind shear over the lower ID Panhandle could support a few organized cells capable of hail and wind gusts in excess of 40 mph but overall, the threat for severe storms (hail and damaging winds) remains low region-wide. Saturday: The upper-low will continue its march east Friday night and Saturday into Central Montana Saturday morning then North Dakota by the evening. Look for drier north to northwest flow over the Cascades and Western Basin Saturday morning to translate east into the Idaho Panhandle by Saturday evening. The main precipitation threat will concentrate over the ID Panhandle and into Western Montana. Some models are more aggressive with the drying so we may be on the high end for precipitation chances in Idaho, especially west of a line from Mullan to the Blue Mtns. Given the lingering cold pool aloft, a few convective showers will be possible in the mountains all the way to the Cascade Crest but these will be the weak and shallow variety producing little to no rainfall. We will also see breezy northerly winds as the low deepens today then pulls out Saturday. Winds will be strongest through the narrow Okanogan Valley and Purcell Trench. Winds sustained 10-20 mph with gusts to 35 mph are a strong possibility. Temperatures will remain on the cool side of normal. /sb Saturday night through Wednesday...General agreement exists between the latest medium range models with the overall field of motion. The general troffy and unsettled pattern will persist through Sunday featuring a continued threat of showers and at least isolated thunderstorms mainly during the afternoon and evening hours and concentrated over the northern mountains...with a few showers persisting well into the night over the Idaho Panhandle. Temperatures in this polar influenced air mass will run at or slightly below normal through Monday. Monday appears to bring a transition from a general trough to a new ridging cycle...with only a few lingering showers over the northeast and panhandle while the remainder of the forecast area dries out and stabilizes under the ridge driven warming aloft. Tuesday through Wednesday bring high confidence of dry and clear/partly cloudy conditions throughout the region as the polar storm track retreats to the north with temperatures once again cresting well above normal. /Fugazzi Wednesday Evening through Thursday Night: Starting Wednesday evening the strength of the ridge will be on the decline as the next trough of low pressure approaches the region. Models are still wavering a bit on the breakdown, but one thing in common for now is Wednesday will be the warmest day of the forecast period. Considering model differences for the breakdown, the GFS continues to be much more aggressive bringing a deep trough swinging through late Thursday. This solution would support another round of widespread rain as the system would have both mid latitude Pacific moisture as well as topical moisture from decaying Tropical Storm Lowell to work with. The euro on the other hand keeps the trough further north leading to a much drier zonal flow pattern for the Pac NW. Either way, we are looking at breezy to windy conditions for the later part of the week as cold air advection coupled with a tightened pressure gradient increases the winds. Both models have been fairly consistent in their respective solutions, so the DGEX was used to help lean in one models favor. It more closely followed the Euro leading to higher confidence in it. So leaning towards the euro, it delays the major threat of precip beyond the reaches of this forecast so POPs were kept relatively low. Temperatures were also raised a bit Thursday to show the transition to a more zonal pattern rather than the cold incoming trough from the GFS. One thing to keep in mind is that when models try to ingest this tropical storm moisture, it often leads to some inconsistent runs. Knowing this, the extended will need to be tinkered with throughout the next couple of days as models align better. /Fliehman && .AVIATION... 06Z TAFS: A SOMEWHAT MOIST AND UNSTABLE AIR MASS ASSOCIATED WITH AN AREA OF LOW PRESSURE WILL CONTINUE TO INFLUENCE THE AVIATION AREA FOR THE NEXT 24 HOURS. DURING THE DAYTIME HOURS SURFACE BASED CONVECTIVE SHOWERS AND THUNDERSTORMS WILL OCCUR, PRIMARILY OVER AND NEAR MOUNTAIN LOCATIONS BUT MOST TAF LOCATIONS WILL BE UNDER THREAT FOR A CLOSE MISS OR BRIEF THUNDERSTORM FRIDAY AFTERNOON AND EVENING. /MJF && .PRELIMINARY POINT TEMPS/POPS... Spokane 75 55 75 54 79 56 / 40 40 10 10 20 30 Coeur d`Alene 73 54 73 51 77 53 / 50 50 10 10 20 30 Pullman 75 51 74 49 79 51 / 40 50 20 20 20 20 Lewiston 80 60 79 56 85 59 / 60 50 30 20 10 20 Colville 72 51 78 49 81 52 / 60 50 10 10 20 30 Sandpoint 69 50 71 46 75 49 / 70 50 10 20 20 30 Kellogg 68 52 67 47 72 53 / 70 60 40 20 30 30 Moses Lake 81 58 83 56 86 58 / 30 50 10 0 10 10 Wenatchee 80 63 82 58 84 64 / 40 50 10 10 20 10 Omak 79 59 82 53 85 58 / 50 40 10 10 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Flash Flood Watch through this evening for East Slopes Northern Cascades-Okanogan Valley-Wenatchee Area. && $$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1151 AM MDT FRI AUG 22 2014 .UPDATE... ISSUED AT 1135 AM MDT FRI AUG 22 2014 CONVECTION CONTINUES IN AREA OF ISENTROPIC LIFT OVER NORTHEASTERN COLORADO. THIS HAD BEEN GRADUALLY LIFTING NORTH...THOUGH WITH HEATING IT HAS BEGUN TO FILL BACK IN TOWARD THE SOUTH. WE WILL NEED TO WATCH THE AREA BETWEEN STERLING AND AKRON AS THIS AREA RECEIVED RAIN EARLIER THIS MORNING. FORTUNATELY THAT IS NOT A FLOOD PRONE AREA. MEANWHILE LARGE AREA OF LIFT IS PROGRESSING NORTHEAST FROM THE SOUTHERN AND CENTRAL MOUNTAINS AND HAS FILLED IN PRETTY WELL WITH RAIN SHOWERS. EXPECT THE MAIN STORY TODAY WILL BE THIS AREA OF FAIRLY STEADY RAIN MOVING NORTHEAST. BIG QUESTION IS THE OUTLOOK FOR STRONGER THUNDERSTORMS...AND THE ANSWER REMAINS MUDDLED BUT ORGANIZED STRONG CONVECTION IS LOOKING LESS LIKELY. FRONTAL ZONE IS RATHER DIFFUSE...THOUGH THERE IS A BROAD AREA OF CONVERGENCE FROM THE CURRENT NE COLORADO CONVECTION SOUTH TOWARD THE ARKANSAS RIVER. LIFT FROM THE UPSTREAM SHORTWAVE IS CREATING PRESSURE FALLS OVER NE COLORADO...HOLDING THIS CONVERGENCE AREA IN PLACE BUT NOT REALLY FOCUSING IT ANY MORE. LARGER SCALE MODELS HAVE A BETTER DEFINED FRONTAL ZONE AND BLOW UP CONVECTION ON IT...WITH HEAVY RAIN ON THE NORTH SIDE AND A POTENTIAL SUPERCELLS NORTH OF THE WARM FRONT SCENARIO WITH STRONG EASTERLY WINDS. MEANWHILE THE HRRR DEVELOPS STORMS ON THE LEADING EDGE OF THE MOUNTAIN RAIN AREA AND THEY MOVE QUICKLY TOWARD THE NORTHEAST...WHILE THE FRONTAL ZONE CONVECTION IS LIMITED TO KANSAS. I DO THINK THE TIGHT FRONTAL ZONE IS WRONG ALONG WITH THE SIGNIFICANT PLUME OF MOISTURE ON LOW LEVEL EASTERLY WINDS...THAT JUST IS NOT HAPPENING. THUS I HAVE PARED BACK THE SEVERE THREAT TO OUR EASTERNMOST AREAS...AND IT IS PROBABLY JUST THE EASTERN PARTS OF LINCOLN AND WASHINGTON COUNTIES AND AREAS EAST OF THERE. AREAS FURTHER WEST AND NORTH WILL STILL HAVE A HEAVY RAIN THREAT IF THERE IS REGENERATION ON AN EAST-WEST ZONE...AND OBVIOUSLY SOME POTENTIAL FOR THAT TO CONTINUE. PREVIOUS OUTLOOKS OF UP TO 3 INCHES IN 2 HOURS IF THERE IS TRAINING SEEM ALRIGHT...BUT THE THREAT SHOULD BE LIMITED TO THOSE EASTERN PLAINS AREAS AS CONVECTION FURTHER WEST SHOULD BE QUITE A BIT WEAKER WITH FAST CELL MOTIONS. && .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 318 AM MDT FRI AUG 22 2014 AN UPPER LEVEL LOW OVER CENTRAL ARIZONA WILL GRADUALLY MOVE NE INTO THE FOUR CORNERS BY MIDDAY AND THEN INTO NE COLORADO BY EARLY THIS EVENING. AS THIS FEATURE MOVES ACROSS A DECENT SHOT OF MID LVL QG ASCENT WILL OCCUR AS WELL. AT THE SFC LOW PRES WILL EXTEND FM SC WY INTO SERN CO WITH A WK SFC HIGH OVER WRN NEBRASKA. THIS WILL ALLOW FOR ESE LOW LVL FLOW TO DVLP BY MIDDAY OVER NERN CO AND ALLOW FOR DEEPER LOW LVL MOISTURE TO ADVECT INTO THE PLAINS. OVERALL SHOULD SEE A GOOD CHC OF SHOWERS AND TSTMS ACROSS MUCH OF THE AREA STARTING IN THE MTNS BY MIDDAY AND THEN SPREADING ACROSS THE PLAINS BY EARLY EVENING. PRECIPITABLE WATER VALUES ARE FCST TO BE AROUND AN INCH IN THE MTNS WITH 1.25 TO 1.5 INCHES OVER THE PLAINS SO THE STORMS WILL PRODUCE HEAVY RAIN...HOWEVER THEY WILL BE QUICK MOVING DUE TO RATHER STG MID LVL FLOW. THERE WILL BE SOME POTENTIAL FOR TRAINING OF CELLS OVER THE PLAINS SO COULD SEE A FEW SPOTS RECEIVE FM 2 TO 3 INCHES OF RAIN. AS FOR SVR POTENTIAL MAIN THREAT WOULD BE STRONG WINDS DUE TO WET MICROBURSTS. ALSO CAN NOT RULE OUT A FEW TORNADOES AS WELL AS STORM RELATIVE HELICITIES INCREASE BY LATE AFTN INTO THE EARLY EVENING HOURS OVER THE PLAINS. AS FOR HIGHS THIS AFTN WILL KEEP READINGS IN THE UPPER 70S TO MID 80S OVER THE PLAINS. BY TONIGHT AS MAIN DISTURBANCE MOVES QUICKLY NE SHOULD SEE PRECIP CHANCES DECREASE ALONG THE FRONT RANGE BY EARLY EVENING AND THEN BY MIDNIGHT OVER THE FAR NERN PLAINS. SOME MOISTURE MAY LINGER IN THE NRN MTNS OVERNIGHT SO WILL KEEP IN A CHC OF SHOWERS MAINLY NORTH OF I-70. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 318 AM MDT FRI AUG 22 2014 A DRIER SOUTHWESTERLY FLOW ALOFT WILL BE OVER NERN CO EARLY SATURDAY FOLLOWING THE PASSAGE OF THE UPPER LEVEL TROUGH. THIS WILL BE SHORT LIVED...AS ANOTHER SYSTEM OVER SRN IDAHO AT 12Z SATURDAY MAKES ITS WAY ACROSS MONTANA/WYOMING LATE SATURDAY AFTERNOON AND SATURDAY NIGHT. THE FLOW ALOFT OVER COLORADO WILL INCREASE FM THE WEST WITH SCATTERED SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS. ALONG THE FRONT RANGE FOOTHILLS...URBAN CORRIDOR AND ADJACENT PLAINS WILL MINIMIZE THE POPS SOUTH AND EAST OF DENVER WITH HIGHER POPS TO THE NORTH AND WEST....AS THE TROF AXIS BRUSHES ACROSS THE STATE. SUNDAY AND SUNDAY NIGHT...A DRIER WESTERLY FLOW ALOFT WILL BE OVER THE CWA. IT WILL BE STABLE AND COOLER FOLLOWING THE PASSAGE OF A COLD FRONT SATURDAY NIGHT INTO SUNDAY MORNING. THE NAM12/ECMWF GENERATE LITTLE QPF OVER THE REGION ON SUNDAY WHILE THE GFS DOES REFLECTS MORE SUBTROPICAL MOISTURE EMBEDDED IN THE FLOW. WL LEAN TOWARD THE NAM12/ECMWF SOLUTIONS WITH MINIMAL POPS MAINLY OVER THE MOUNTAINS IN THE AFTN/EVNG. SUNDAY NIGHT INTO MONDAY...THE FLOW ALOFT BECOMES MORE SOUTHWESTERLY WHICH MAY HELP TAP INTO THE SUBTROPICAL MOISTURE OVER ERN AZ/NEW MX. POPS STILL ON THE LOW SIDE MONDAY AFTERNOON/EVENING. THE NEXT SYSTEM IS PROGGED TO DROP OUT OF THE NORTHERN ROCKIES AND ACROSS COLORADO TUESDAY AND TUESDAY NIGHT. THE TROUGH AXIS AND ITS ASSOCIATED COLD FRONT WILL PASS ACROSS NORTHERN COLORADO ON TUESDAY. IT WILL BE COOLER WITH A BETTER CHANCE OF SHOWERS AND TSTMS AT THAT TIME. WEDNESDAY INTO THURSDAY...AN UPPER RIDGE DEVELOPS OVER THE WESTERN U.S. WITH A DRIER NORTHWESTERLY FLOW ALOFT OVER COLORADO. AS A RESULT...LESS POPS WITH MODERATING TEMPERATURES FOR THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE TAFS THROUGH 18Z SATURDAY MORNING) ISSUED AT 1135 AM MDT FRI AUG 22 2014 SHOWERS WILL BE FAIRLY WIDESPREAD AROUND THE DENVER AREA THROUGH THIS EVENING...WITH EMBEDDED THUNDERSTORMS. THE THREAT OF VERY HEAVY RAIN WITH IFR CONDITIONS IS NOW LOOKING LOW...BUT THERE SHOULD BE ENOUGH RAIN TO LOWER CEILINGS/VISIBILITIES WITH AREAS OF MVFR IN THE LATE AFTERNOON AND EVENING. IT APPEARS THAT CLEARING WILL BE SLOWER ON SATURDAY MORNING...BUT THERE IS STILL A LOW CHANCE OF IFR/LIFR FOG FOR A FEW HOURS IF IT DOES CLEAR OUT EARLY ENOUGH. FOR THE REST OF SATURDAY VFR CONDITIONS ARE EXPECTED WITH ONLY ISOLATED LATE AFTERNOON THUNDERSTORMS. && .HYDROLOGY... ISSUED AT 318 AM MDT FRI AUG 22 2014 STORMS WILL MOVE QUICKLY TODAY HOWEVER THERE WILL BE SOME POTENTIAL FOR TRAINING OF STORMS OVER NORTHEAST COLORADO AS A FEW LOCATIONS COULD SEE UP TO 2 INCHES OF RAIN IN LESS THAN HOUR. IN THE FOOTHILLS AND MTNS ISOLATED AMOUNTS UP TO AN INCH IN LESS THAN AN HOUR WILL BE POSSIBLE WITH SOME MINOR FLOODING IN THE BURN SCARS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GIMMESTAD SHORT TERM...RPK LONG TERM...COOPER AVIATION...GIMMESTAD HYDROLOGY...RPK
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1125 AM MDT FRI AUG 22 2014 .UPDATE... ISSUED AT 1054 AM MDT FRI AUG 22 2014 UPDATED TO INCREASE PRECIPITATION CHANCES ACROSS ALL OF SOUTHERN COLORADO THROUGH THIS AFTERNOON. RAIN HAS STARTED TO BLOSSOM ON RADAR ACROSS THE REGION LATE THIS MORNING...AND AS THE UPPER SYSTEM OVER NORTHWEST NEW MEXICO LIFTS ACROSS COLORADO...IT SHOULD PROVIDE FOCUS FOR RAINFALL AND THUNDERSTORM ENHANCEMENT. STILL WATCHING THE POTENTIAL FOR HEAVIER RAINFALL OVER PORTIONS OF THE AREA...FROM FREMONT COUNTY...NORTHEAST OVER TELLER AND EL PASO COUNTIES FOR THIS AFTERNOON. DEWPOINTS HAVE CLIMBED INTO THE 50S WITH NORTHEASTERLY UPSLOPE FLOW ARE WORKING IN FAVOR OF THE HEAVY RAIN POTENTIAL...HOWEVER DENSE CLOUD COVER WILL HELP LIMIT INSTABILITY AND MAY HELP KEEP RAINFALL RATES DOWN. THE MAIN CAVEAT WILL BE HOW THE UPPER LEVEL SYSTEM IMPACTS THE LOWER LEVEL INGREDIENTS. WHILE A FLASH FLOOD WATCH IS NOT IN EFFECT AT THIS TIME DUE TO THE UNCERTAINTY OF RAINFALL RATES...PEOPLE IN AND AROUND FLASH FLOOD PRONE AREAS SHOULD BE ON ALERT THROUGH AT LEAST 6 PM THIS EVENING. MOZLEY && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 450 AM MDT FRI AUG 22 2014 ...POTENT STORM SYSTEM TO WILL BRING FAST MOVING THUNDERSTORMS CAPABLE OF LOCALLY HEAVY RAINFALL...SMALL HAIL...AND LIGHTNING TO SOUTH CENTRAL AND SOUTHEAST COLORADO...WITH POTENTIAL FOR SEVERE WEATHER FOR NORTHERN PORTIONS OF THE SOUTHEAST PLAINS BY AFTERNOON... UPPER LOW OVER WESTERN AZ IS FORECAST TO EJECT TO THE NORTHEAST TODAY...AS THE KICKER SYSTEM DROPS THROUGH THE PACIFIC NORTHWEST. ALREADY HAVE A ROUND OF THUNDERSTORMS ONGOING ACROSS EAST CENTRAL AND NORTHEAST COLORADO ALONG/NORTH OF THE FRONT AS THE FIRST UPPER JET LIFTS OFF TO THE NORTHEAST. THESE WILL CONTINUE TO LIFT OFF TO THE NORTHEAST THIS MORNING...AND FOCUS FOR PRECIPITATION WILL TO SHIFT INTO WESTERN PORTIONS OF THE FORECAST AREA THIS MORNING AS MOISTURE AND LIFT INCREASES WITH THE NEXT IMPULSE AHEAD OF THE ADVANCING SYSTEM. SO FAR...RAINFALL RATES OUT WEST DO NOT LOOK HEAVY ENOUGH TO CAUSE CONCERNS FOR THE WEST FORK BURN SCAR...BUT THIS WILL HAVE TO BE MONITORED CLOSELY THROUGH THE MORNING. OF GREATER CONCERN WILL BE POTENTIAL FOR THUNDERSTORMS ACROSS THE SOUTHEAST MOUNTAINS THIS AFTERNOON AS UPPER TROF LIFTS ACROSS THE AREA DURING PEAK HEATING PERIOD. SFC LOW ACROSS SOUTHERN CO IS PROGGED TO LIFT BACK NORTHWARD DURING THE AFTERNOON...WITH FRONTAL BOUNDARY BECOMING THE FOCUS FOR STRONG TO EVEN SEVERE THUNDERSTORMS THIS AFTERNOON AS IT LIFTS BACK NORTHWARD. VARIOUS SHORT RANGE MODELS SHOW THIS LIFTING BACK NORTHWARD TO ALONG A LINE FROM COLORADO SPRINGS TO EADS AS OF 21Z. DEPENDING ON SFC DEW POINTS...CAPES COULD BE RUNNING ANYWHERE FROM 1000 J/KG TO 1500 J/KG TO THE NORTH OF THIS BOUNDARY...AND WITH NEXT UPPER JET SHIFTING NORTHWARD INTO THE REGION...COULD SEE DEEP LAYER SHEARS 40KTS...ESP WHERE LOW LEVEL SFC WINDS REMAIN EASTERLY. SEEMS BEST THREAT AREA FOR SEVERE POTENTIAL WILL BE ACROSS NORTHEAST EL PASO AND KIOWA COUNTIES...AND POINTS TO THE NORTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY STORM THREATS. WITH UPPER LEVEL FORCING MOVING ACROSS DURING THE AFTERNOON...HIGH RES AND CONCEPTUAL MODELS SUGGEST A LINE OF THUNDERSTORMS WILL DEVELOP ACROSS THE SOUTHEAST MOUNTAINS AND MOVE OFF TO THE NORTHEAST THROUGH THE AFTERNOON AND EARLY EVENING. LOCALLY HEAVY RAINFALL...SMALL HAIL...AND ERRATIC GUSTY WINDS UP TO 50 MPH WILL BE THE MAIN STORM THREATS. QUESTION IS...WILL THUNDERSTORMS BE CAPABLE OF PRODUCING ENOUGH RAINFALL TO CAUSE FLASH FLOODING ON AREA BURN SCARS. STORM MOTIONS TODAY WILL BE NORTH TO NORTHEAST AT AROUND 30- 35 MPH...WHICH SHOULD MITIGATE THIS THREAT SOME. HOWEVER THE WALDO BURN SCAR WITH ITS VERY LOW FLASH FLOOD THRESHOLD LOOKS TO MOST UNDER THE THREAT TODAY. IF SUFFICIENT HEATING CAN TAKE PLACE...WE COULD SEE CAPES OF NEAR 1000 J/KG (WITH SFC DEW POINTS IN THE LOWER 50S). IF FRONTAL BOUNDARY LIFTS BACK NORTHWARD INTO THIS REGION AND STALLS...THEN THIS COULD ALSO PROVIDE A FOCUS FOR A COUPLE OF ROUNDS OF THUNDERSTORMS. HOWEVER...MODELS ARE NOT ALL IN AGREEMENT OF WHERE THE HEAVIER PRECIPITATION WILL FALL. 06Z NAM12 IS THE HEAVIEST HANDED WITH QPF AMOUNTS OF OVER AN INCH FALLING ACROSS NORTHERN EL PASO AND TELLER COUNTIES DURING THE NOON TO 6 PM TIME FRAME. HOWEVER RAP13...GFS...AND ECMWF ALL KEEP PRECIPITATION AMOUNTS MUCH LIGHTER AROUND .25 TO CLOSE TO .50...AND ALL MODELS SEEM TO POINT AT THE QPF MAXIMUM OCCURRING ACROSS NORTHEAST COLORADO GIVEN THE CURRENT STORM TRACK. STILL CONTEMPLATING ISSUING A FLASH FLOOD WATCH FOR WALDO BURN SCAR TODAY. SOME FACTORS THAT FAVOR FLASH FLOODING TODAY FOR THE WALDO WOULD BE HIGHER PRECIPITABLE WATERS...GOOD FORCING WITH SHORTWAVE MOVING ACROSS DURING THE AFTERNOON...SOME POTENTIAL INSTABILITY IN THE AFTERNOON...AND EVEN A BRIEF PERIOD OF SOUTHEAST UPSLOPE BEFORE 00Z. SOME FACTORS THAT DO NOT PARTICULARLY FAVOR FLASH FLOOD POTENTIAL FOR WALDO INCLUDE FAST STORM MOTIONS...EXTENSIVE MORNING CLOUD COVER...WARMING H5 TEMPERATURES AHEAD OF THE UPPER LOW TODAY...AND QUICK SHIFT TO A SOUTHWEST DOWNSLOPE FLOW BY 00Z AS SYSTEM LIFTS TO THE NORTHEAST OF THE AREA. WOULD LIKE TO SEE A FEW RUNS OF THE HRRR RESOLVE SOME OF THESE MESOSCALE DETAILS BEFORE COMMITTING TO A WATCH. AM CONFIDENT THAT SOMEWHERE CLOSE BY...LIKELY TO THE NORTHEAST OF THE BURN SCAR...QPF AMOUNTS OF AN INCH OR MORE WILL BE POSSIBLE WITH THE STRONGER STORMS. BUT NOT CONFIDENT ENOUGH THAT THIS WILL HAPPEN ON WALDO TO GO WITH A WATCH. WILL CONTINUE TO MONITOR LATEST HIGH RES MODELS THROUGH THE MORNING AND MAY HOIST A WATCH AS DETAILS BECOME BETTER RESOLVED. REGARDLESS...ANYONE IN OR NEAR THE BURN SCARS TODAY NEEDS TO MAINTAIN A HEIGHTENED AWARENESS OF THE WEATHER TODAY. TIMEFRAME WITH THE GREATEST THREAT APPEARS TO BE BETWEEN NOON AND 6 PM. THUNDERSTORMS WILL DIMINISH RAPIDLY THIS EVENING AS THE SYSTEM LIFTS OFF TO THE NORTHEAST. SOME SHOWERS MAY LINGER ALONG THE CONTINENTAL DIVIDE PAST MIDNIGHT AS THE NEXT UPPER TROF DROPS IN FROM THE NORTHWEST. -KT .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 450 AM MDT FRI AUG 22 2014 PRIMARY LONGER TERM METEOROLOGICAL CHALLENGES INCLUDE POPS...TEMPERATURES AND EVEN SOME GUSTY WINDS AT TIMES. LATEST COMPUTER SIMULATIONS AND FORECAST MODEL SOUNDINGS SUGGEST THAT ADEQUATE ATMOSPHERIC MOISTURE WILL INTERACT WITH SEVERAL UPPER DISTURBANCES INTO THE MIDDLE PORTION OF NEXT WEEK. IN ADDITION...A NORTHERLY SURGE IS PROJECTED TO PUSH ACROSS EASTERN SECTIONS OF THE FORECAST DISTRICT TUESDAY NIGHT. THE COMBINATION OF THESE FEATURES IS EXPECTED TO GENERATE ISOLATED TO SCATTERED POPS AT TIMES OVER THE MAJORITY OF THE FORECAST DISTRICT FROM FRIDAY INTO NEXT WEDNESDAY(ESPECIALLY IF THE LATEST VERSION OF THE ECMWF IS CORRECT) WITH SOME DRYING THEN ANTICIPATED BY LATER NEXT WEEK. IN ADDITION...MAXIMUM AND MINIMUM TEMPERATURES ARE EXPECTED TO RUN WITHIN A CATEGORY OR SO OF LATE AUGUST CLIMATOLOGICAL AVERAGES DURING THE LONGER WHILE GUSTY GRADIENT WINDS WILL BE POSSIBLE AT TIMES(PRIMARILY OVER FAR EASTERN SECTIONS) FROM SATURDAY INTO SATURDAY NIGHT AND THEN AGAIN FROM SUNDAY NIGHT INTO TUESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1054 AM MDT FRI AUG 22 2014 AN UPPER LEVEL STORM SYSTEM WILL MOVE ACROSS COLORADO THROUGH THIS EVENING WITH WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY IMPACTING ALL THREE TERMINALS. LOWERED CIGS AND VISIBILITIES ARE EXPECTED THIS AFTERNOON AT ALL THREE TERMINALS...WITH LOCALLY HEAVY RAINFALL EXPECTED. MODELS IN GOOD AGREEMENT WITH THE THUNDERSTORM ACTIVITY ENDING AROUND 00Z/SAT AND GENERALLY FOLLOWED THIS TREND IN THE TAFS. MOZLEY && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MOZLEY AVIATION...MOZLEY
AREA FORECAST DISCUSSION
NWS ALBANY NY
430 PM EDT FRI AUG 22 2014 .SYNOPSIS... AN UPPER LEVEL LOW OVER NEW ENGLAND WILL CONTINUE TO MOVE AWAY FROM THE REGION TONIGHT...ENDING THE THREAT FOR SHOWERS. AS HIGH PRESSURE BUILDS INTO THE AREA...IMPROVING CONDITIONS ARE EXPECTED OVER THE WEEKEND...WITH GRADUALLY MORE AMOUNTS OF SUNSHINE AND WARMER TEMPERATURES. WITH DRY WEATHER IN PLACE...ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR MUCH OF THE UPCOMING WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 430 PM EDT...AN UPPER LEVEL LOW IS SITUATED JUST EAST OF THE AREA OVER EASTERN NEW ENGLAND. LOW LEVEL MOISTURE REMAINS HIGHS OVER THE REGION WITH DEWPOINTS STILL IN THE 60S...AND PWAT VALUES AROUND 1.50 INCHES. WEAK IMPULSES EMBEDDED WITHIN THE CYCLONIC FLOW AROUND THIS UPPER LEVEL LOW ARE ALLOWING FOR PLENTY OF CLOUDS AND SOME ON AND OFF RAIN SHOWERS. NO THUNDER HAS BEEN OCCURRING DUE TO A LACK OF INSTABILITY THANKS TO THE THICK CLOUD COVER IN PLACE. THE LATEST REGIONAL MOSAIC RADAR SHOWS THE MOST CONCENTRATED ACTIVITY OF SHOWERS IS CURRENTLY SOUTHWEST OF THE AREA OVER CENTRAL NY. THE SHOWERS HAVE BEEN RATHER SLOW MOVING TODAY DUE TO THE LIGHT FLOW DUE TO THE UPPER LEVEL LOW NEARBY. THE LATEST 18Z 3KM HRRR MATCHES UP WELL WITH THE CURRENT RADAR...AND SHOWS A DECREASING TREND IN THE COVERAGE AND INTENSITY OF RAIN SHOWERS TOWARDS EVENING. AS THE UPPER LEVEL LOW STARTS TO MOVE AWAY...AND DIURNAL INFLUENCES BEGAN TO WANE...THIS SEEMS TO MAKE SENSE...SO HAVE DECREASED POPS FROM LIKELY AND HIGH CHANCE TO JUST SLIGHT TO LOW CHC FOR THE OVERNIGHT HOURS. WITH ALL THE LOW LEVEL MOISTURE IN PLACE...WILL KEEP CLOUDS IN PLACE THROUGH THE DURATION OF THE OVERNIGHT HOURS. WILL ALSO ALLOW FOR SOME PATCHY/AREAS OF FOG FOR VALLEY LOCATIONS FOR THE SECOND HALF OF THE NIGHT AS WELL WITH ALL THE LOW LEVEL MOISTURE PRESENT. OVERNIGHT LOWS LOOK TO RANGE FROM THE MID 50S TO LOW 60S. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... A DRYING AND WARMING TREND WILL TAKE PLACE THROUGH THE SHORT TERM PERIOD. HIGH PRESSURE OVER SOUTHERN CANADA WILL BUILD SOUTHWARD INTO THE REGION ON SATURDAY. WHILE THERE MAY BE A LINGERING RAIN SHOWER ON SATURDAY /MAINLY FOR SOUTHERN OR HIGH TERRAIN AREAS/...MOST AREAS WILL BE DRYING OUT. CLOUDS SHOULD BREAK FOR SOME SUN FROM NORTH TO SOUTH DURING THE AFTERNOON HOURS...AS DRIER AIR BEGINS TO WORK IN FROM SOUTHERN CANADA. MAX TEMPS LOOK TO REACH THE 70S FOR MOST LOCATIONS. DRY AND QUIET WEATHER WILL BE IN PLACE BETWEEN SATURDAY NIGHT AND SUNDAY NIGHT. OVERNIGHT LOWS LOOK TO BE IN THE 50S...AND DAYTIME HIGHS ON SUNDAY LOOK TO REACH THE MID 70S TO LOW 80S. SKIES LOOK TO BE MOSTLY CLEAR DURING THIS TIME PERIOD. && .LONG TERM /MONDAY THROUGH FRIDAY/... A DRY START TO THE PERIOD FOLLOWED BY POSSIBLE POST-FRONTAL SHOWERS TOWARD THE END OF THE WORK WEEK...THEN A RETURN TO DRY WEATHER FOR THE START OF THE WEEKEND. SUNSHINE WILL BE PLENTIFUL THROUGH MID- WEEK...WITH PARTLY TO MOSTLY CLOUDY SKIES THEREAFTER. HIGH TEMPERATURE READINGS FROM MAINLY THE LOWER 70S TO MID 80S WILL BE THE RULE MONDAY AND TUESDAY...WITH SLIGHTLY WARMER READINGS FOR WEDNESDAY. BEHIND THE FRONT...THINGS COOL DOWN TO HIGHS FROM THE MID 60S TO MID 70S BY FRIDAY. LOWS WILL BE PRIMARILY IN THE 50S OR LOWER 60 UNTIL FRIDAY NIGHT...WHEN READINGS WILL RANGE FROM THE UPPER 40S IN THE WESTERN ADIRONDACKS...TO AROUND 60 DEGREES IN THE LOWER MID HUDSON VALLEY. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... PREDOMINATELY MVFR FLYING CONDITIONS WILL PREVAIL THROUGHOUT THE TAF PERIOD AS SCATTERED DRIZZLE/SHOWERS FROM A SLOWLY DEPARTING LOW PRESSURE SYSTEM CONTINUE TO AFFECT THE REGION. THIS AFTERNOON...SCATTERED DRIZZLE/SHOWERS WILL CONTINUE INTO THE EVENING HOURS RESULTING IN MVFR CEILINGS...WITH THE BEST CHANCE FOR SHOWERS AT KALB THROUGH 20Z. HAVE INCLUDED A TEMPO GROUP AT KALB AS WELL FROM 18Z TO 20Z TO ACCOUNT FOR BRIEF REDUCTIONS TO IFR CEILINGS ASSOCIATED WITH NEARBY SHOWERS. ELSEWHERE EXPECT OCCASIONAL DRIZZLE/MIST THAT MAY ALLOW FOR BRIEF REDUCTIONS TO MVFR VISIBILITIES. WINDS WILL BE OUT OF THE EAST/SOUTHEAST AND LIGHT AROUND 5 KNOTS. TONIGHT INTO SATURDAY...MVFR CEILINGS WILL CONTINUE THROUGH THE OVERNIGHT PERIOD WITH MVFR VISIBILITIES ALSO EXPECTED AFTER 06Z. SHOWER ACTIVITY WILL GRADUALLY DECREASE DURING THE NIGHT AS WELL. IFR CEILINGS WILL BE POSSIBLE AT KPSF AFTER 09Z BEFORE DRIER AIR ALLOWS VFR FLYING CONDITIONS TO RETURN TO THE TAF SITES BY 15Z SATURDAY...EXCEPT AT KPSF WHERE MVFR CEILINGS WILL CONTINUE THROUGH AT LEAST 18Z SATURDAY. WINDS WILL BE LIGHT AND VARIABLE LESS THAN 5 KNOTS TONIGHT AND INTO SATURDAY. OUTLOOK... SATURDAY NIGHT THROUGH WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... SCATTERED SHOWERS INTO TONIGHT WILL KEEP FIRE WEATHER CONCERNS AT A MINIMUM. RH VALUES WILL BE NEAR 100 PERCENT TONIGHT. WINDS WILL GENERALLY BE LIGHT AND VARIABLE TONIGHT. TOMORROW...THE RH VALUES WILL DROP TO 50 TO 60 PERCENT DURING THE AFTERNOON HOURS WITH CLOUDS BREAKING FOR SOME SUNSHINE. THERE IS JUST A SLIGHT CHANCE FOR A RAIN SHOWER OVER THE HIGH TERRAIN AND SOUTHERN PARTS OF THE AREA. WINDS WILL CONTINUE TO BE LIGHT AND VARIABLE. && .HYDROLOGY... RECENT HEAVY RAINFALL LED TO FLOODING LAST NIGHT ACROSS PARTS OF THE MOHAWK VALLEY...AND SMALLER RIVERS AND STREAMS CONTINUE TO BE HIGH ACROSS THIS AREA DUE TO SHOWERS FROM THIS MORNING. THE GROUND REMAINS RATHER SATURATED IN THE SACANDAGA AND SARATOGA REGION AS WELL. ELSEWHERE...THERE HAVE BEEN PERIODS OF SHOWERS FROM TIME TO TIME AS WELL...BUT RAINFALL AMOUNTS HAVEN/T BEEN OVERLY EXCESSIVE. THERE MAY BE A FEW ADDITIONAL RAIN SHOWERS BETWEEN LATE TONIGHT AND INTO TONIGHT...BUT RAINFALL RATES ARE EXPECTED TO BE LIGHT FOR THE MOST PART. THE ONLY WAY ANY ADDITIONAL FLOODING WOULD OCCUR WOULD BE IF A HEAVY RAIN SHOWER HAPPENED TO SIT OVER A LOCATION THAT SAW SIGNIFICANT RAINFALL LAST EVENING/NIGHT...OTHERWISE NO ADDITIONAL FLOODING IS EXPECTED. THE COVERAGE OF SHOWERS WILL DIMINISH BY LATER THIS EVENING. THE ONLY RIVER POINT THAT IS CLOSE TO FLOOD STAGE IS THE CANAJOHARIE CREEK AT CANAJOHARIE. THE RIVER HAS CRESTED JUST BELOW FLOOD STAGE AFTER THIS MORNING/S ADDITIONAL BOUT OF RAIN...AND LOOKS TO CONTINUE TO RECEDE. THE RECESSION MAY BE SLOWED IF ADDITIONAL RAINFALL FALLS OVER THE BASIN...BUT THE GENERAL TREND WILL BE TO FALL. OVER THE WEEKEND AND INTO EARLY NEXT WEEK...A DRYING TREND WILL BE IN PLACE...WITH JUST A SLIGHT CHANCE FOR A BRIEF LIGHT RAIN SHOWER OVER THE HIGH TERRAIN ON SATURDAY. THIS WILL ALLOW FOR THE GROUND TO DRY OUT...AND RIVER AND STREAM LEVELS TO SLOWLY RECEDE. 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...FRUGIS NEAR TERM...FRUGIS SHORT TERM...FRUGIS LONG TERM...ELH AVIATION...IRL FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
618 PM EDT FRI AUG 22 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL THROUGH THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL LINGER SOUTH OF THE CSRA EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /THROUGH SATURDAY/... 88D REGIONAL COMPOSITE SHOWS A FEW ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE UPSTATE...PEE DEE AND CENTRAL GEORGIA. ATMOSPHERE REMAINS CAPPED ACROSS THE MIDLANDS AND AIRMASS IS DRIER WITH DEWPOINT TEMPERATURES IN THE UPPER 50S TO MIDDLE 60S. ONLY EXPECT AN ISOLATED SHRA/TSRA THROUGH EARLY EVENING. FORECAST AGRESS WELL WITH HRRR AS IT SHOWS ANY ACTIVITY REMAINING NORTH OF THE CWA. SURFACE LOW PRESSURE ALONG THE VA COAST IS FORECAST TO MOVE SOUTHWARD OVERNIGHT INTO EASTERN NC. THIS WILL ALLOW A BACKDOOR COLD FRONT TO APPROACH THE NORTHERN MIDLANDS AROUND DAYBREAK SATURDAY. KEPT OVERNIGHT LOWS NEAR CONSENSUS IN THE LOWER AND MIDDLE 70S. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS IN GOOD AGREEMENT WITH MOVING THE FRONT SOUTH OF THE SAVANNAH RIVER WITH UPPER LEVEL RIDGE BUILDING IN FOR THE WEEK. WITH COOLER DRY AIR SETTLING IN WILL BRING SLIGHTLY BELOW NORMAL TEMPS. EXPECT MAX TEMPS 85 TO 90 EARLY TO MID WEEK RISING BACK INTO THE LOWER 90S LATER IN THE WEEK. OVERNIGHT MINS WILL BE 65 TO 70 RISING INTO THE LOWER 70S LATER IN THE WEEK. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. DIURNAL WIDELY SCATTERED CUMULUS AOA 6-7 KFT ACROSS THE REGION THIS AFTERNOON...BUT THIS WILL BE DIMINISHING THIS EVENING WITH LOSS OF HEATING. GIVEN FRONTAL BOUNDARY REMAINING WELL NORTH OF THE AREA...CHANCE FOR CONVECTION TOO LOW TO INCLUDE IN TAFS ATTM. NORTHWEST TO WEST WINDS 10 KNOTS OR LESS THIS AFTERNOON WILL DIMINISH AND VEER NORTHERLY OVERNIGHT. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SUNDAY AND MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS SATURDAY AND SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1118 AM CDT FRI AUG 22 2014 .DISCUSSION... 935 AM CDT THE MAIN CORRIDOR OF HEAVY RAIN LATE LAST NIGHT INTO EARLY THIS MORNING HAS SHIFTED INTO CENTRAL IL AND WEAKENED...HOWEVER AN AREA OF THUNDERSTORM ACTIVITY HAS BUILT FROM EASTERN IA INTO WESTERN IL AS OF 930 AM. THIS IS ASSOCIATED WITH A SHORT WAVE AND APPEARS BY RADAR AND SATELLITE ALSO MAS AN MCV WITH IT. SHORT TERM GUIDANCE VARIES WIDELY ON HOW THIS WILL UNFOLD BUT GIVEN ITS ORGANIZATION WOULD EXPECT FOR IT TO PROGRESS EASTWARD ALONG AN AXIS OF CONFLUENT FLOW AT 850-700MB. RAINFALL RATES HAVE TAPERED IN THE PAST HALF HOUR...BUT STILL IN A VERY MOIST ATMOSPHERE /PWATS OVER TWO INCHES/ WE ARE SEEING RAINFALL RATES IN EXCESS OF ONE INCH PER HOUR AT TIMES WITH THIS. PARTS OF LASALLE AND LIVINGSTON COUNTIES WERE HIT HARD LAST NIGHT INTO EARLY THIS MORNING...SO THRESHOLDS FOR FLASH FLOOD WARNINGS WILL LIKELY BE LOW IF THIS AREA WERE TO GET ANY MORE AGGRESSIVE OR SLOW DOWN. BASED ON CALLS TO EMERGENCY MANAGEMENT AND LAW ENFORCEMENT PARTNERS...EARLIER FLASH FLOOD WARNINGS WERE TRANSITIONED TO AREAL FLOOD WARNINGS WHERE MAJOR IMPACTS WERE STILL OCCURRING. THE SAME MAY BE DONE FOR PART OF LIVINGSTON/LASALLE/GRUNDY COUNTY DEPENDING ALSO ON HOW EARLIER MENTIONED CONVECTION IS EVOLVING. THE DENSE FOG ADVISORY FOR LAKE AND MCHENRY COUNTIES WILL BE ALLOWED TO EXPIRE AT 10 AM AS OBSERVATIONS AND WEBCAMS HAVE SHOWN IMPROVEMENT. WILL LIKELY HAVE TO LOWER HIGH TEMPERATURE FORECAST SOME BASED ON DEGREE OF CLOUD COVER OVER THE AREA. CONTINUED DEW POINTS OF 70 TO 75 WILL KEEP IT FEELING MUGGY. MTF //PREV DISCUSSION... 349 AM...FORECAST CONCERNS INCLUDE HEAVY RAIN WITH THUNDERSTORMS THROUGH SATURDAY NIGHT...IN ADDITION TO TIMING AND LOCATION OF STORMS. ADDITIONAL CONCERNS AND CHALLENGES INCLUDE TEMPERATURES/ DEWPOINTS AND ASSOCIATED HEAT INDICES THROUGH EARLY NEXT WEEK. ONE COMPLEX OF THUNDERSTORMS MOVING ACROSS FAR NORTHEAST IL AND NORTHWEST INDIANA WITH A SECOND COMPLEX MOVING SOUTHEAST ACROSS THE SOUTHERN CWA. THESE ARE VERY EFFICIENT RAIN PRODUCES WITH DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES AROUND 2 INCHES. COOP OBSERVER 3SW OF MIDWAY AIRPORT MEASURED 3.60 INCHES OF RAIN IN JUST 40 MINUTES WITH SEVERAL REPORTS OF FLOODED ROADS IN THAT AREA. WHILE ADDITIONAL ACTIVITY CONTINUES ACROSS THE AREA...THE GENERAL TREND IS FOR ALL THIS ACTIVITY TO MOVE SOUTHEAST THIS MORNING. HOWEVER...ADDITIONAL ACTIVITY OVER WESTERN IL AND SOUTHERN IOWA MAY CONTINUE MOVING EAST ACROSS THE SOUTHERN CWA LATER THIS MORNING. CONVECTIVE TRENDS ARE STILL SOMEWHAT UNCERTAIN OVER THE NEXT 36 HOURS OR SO. IF CURRENT ACTIVITY ACROSS SOUTHERN IA/WESTERN IL DRIFTS SOUTHEAST...MUCH OF THE DAYLIGHT HOURS COULD END UP RATHER DRY WITH TONIGHT POSSIBLY BEING MORE ACTIVE AS HINTED AT BY THE ECMWF. HAVE TRENDED THIS DIRECTION BUT CONFIDENCE IS LOW. WITH DEWPOINTS REMAINING IN THE LOWER/MID 70S AND PRECIPITABLE WATER VALUES REMAINING AROUND 2 INCHES...ADDITIONAL TORRENTIAL RAIN WILL BE POSSIBLE WITH ANY STORMS THAT DEVELOP. IF TRENDS BECOME MORE CLEAR...ITS POSSIBLE A FLASH FLOOD WATCH MAY BE NEEDED FOR PART OF THE AREA...BUT GIVEN THE UNCERTAINTY OF WHEN/WHERE ADDITIONAL HEAVY RAIN WILL OCCUR...NO HEADLINES THIS MORNING. CONVECTION THEN APPEARS TO SHIFT NORTHEAST DURING THE DAY ON SATURDAY AS THE UPPER RIDGE BUILDS INTO THE AREA. THUS A DRY PERIOD IS EXPECTED FROM LATER SATURDAY NIGHT THROUGH SUNDAY NIGHT AND POSSIBLY INTO MUCH OF THE DAY ON MONDAY. CHANCE POPS THEN ENTER BACK INTO THE FORECAST THROUGH THURSDAY. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT WITH A COLD FRONT MOVING ACROSS THE AREA MIDWEEK...THOUGH TIMING DIFFERENCES REMAIN. ADDITIONAL HEAVY RAIN WILL BE POSSIBLE DURING THIS TIME AS WELL. WHILE SUNDAY MAY END UP BEING COMPLETELY DRY AS THE RIDGE CAPS THE AREA...IT DOES APPEAR THERE COULD BE A LAKE BREEZE ALONG THE IL SHORE SUNDAY AFTERNOON. HOW MUCH CONVERGENCE OCCURS IS UNCERTAIN BUT GIVEN HOW WARM/HUMID CONDITIONS WILL BE SUNDAY AFTERNOON...IF THIS IS ENOUGH FOR THUNDERSTORMS TO DEVELOP...THERE COULD BE SOME LOCALLY HEAVY RAIN ACROSS FAR NORTHEAST IL. ADDED SLIGHT CHANCE POPS DURING THIS TIME TO ACCOUNT FOR THIS POTENTIAL. DENSE FOG HAS FORMED ACROSS FAR NORTHEAST IL AND MAY SPREAD SOUTHWEST INTO NORTHWEST IL EARLY THIS MORNING AS RAIN ENDS. ISSUED A DENSE FOG ADVISORY FOR LAKE/MCHENRY COUNTIES EARLIER THIS MORNING AND MAY NEED TO EXPAND THAT AS TRENDS EMERGE. DEPENDING ON PRECIP COVERAGE TONIGHT...AREAS OF FOG POSSIBLY DENSE MAY DEVELOP AGAIN INTO SATURDAY MORNING. TEMPERATURES TODAY AND SATURDAY WILL BE DEPENDENT ON CLOUD COVER AND PRECIP COVERAGE. MADE ONLY SMALL TWEAKS...BASICALLY NO CHANGES. DID BUMP TEMPS UP A FEW DEGREES ON SUNDAY AND MONDAY WITH EXPECTED LESS OR NO PRECIP AND MORE SUNSHINE. OVERNIGHT LOWS WILL LIKELY REMAIN IN THE LOWER 70S MOST AREAS...POSSIBLY MID OR UPPER 70S DOWNTOWN CHICAGO SUNDAY NIGHT/MONDAY MORNING. FORECAST HEAT INDICES WILL BE NEAR 100 TODAY...RETREAT JUST A LITTLE SATURDAY AND THEN AGAIN NEAR 100 SUNDAY AND MONDAY. ACROSS THE SOUTHERN CWA...HEAT INDICES APPROACH THE 105 MARK. IF CURRENT TRENDS CONTINUE...ITS POSSIBLE PORTIONS OF THE SOUTHERN CWA MAY NEED A HEAT ADVISORY SUNDAY/MONDAY. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * MVFR CIGS GRADUALLY LIFTING AND POSSIBLY SCATTERING THROUGH EARLY-MID AFTERNOON. * LIGHT SOUTHWEST WINDS TURNING EAST-NORTHEAST EARLY THIS AFTERNOON. SPEEDS EXPECTED TO BE UNDER 10 KT THROUGH THAT TIME. * ISOLD SHRA/TSRA POSSIBLE THIS AFTERNOON. MAY DEVELOP WEST OF TERMINALS AND DRIFT BACK TO THE EAST. * CHANCES FOR SHRA/TSRA TONIGHT AND SATURDAY MORNING...TIMING UNCLEAR. MDB/MTF //DISCUSSION...UPDATED 12Z... WEAK LOW PRESSURE EXTENDS FROM SOUTHERN MINNESOTA/NORTHERN IOWA SOUTHWEST INTO THE SOUTHERN PLAINS. A FRONTAL BOUNDARY EXTENDS FROM EASTERN IOWA ACROSS NORTHERN ILLINOIS TO NORTHERN INDIANA THIS MORNING WITH STRONG LOW LEVEL WINDS HELPING DRIVE THUNDERSTORM ACTIVITY TO THE SOUTH OF THE TERMINALS. SOME SPOTTY IFR IS IN PROXIMITY TO THE TERMINALS...WITH THE BULK NEAR RFD BUT THIS SHOULD BE IMPROVING...WITH ORD/MDW/DPA/GYY LIKELY SEEING LITTLE IF ANY IFR. LIGHT AND SOMEWHAT VARIABLE SOUTH TO SOUTHWEST WINDS ARE IN PLACE BUT ARE EXPECTED TO TURN EAST AND NORTHEAST THIS AFTERNOON AS THE FRONT RE-ESTABLISHES ITSELF PERHAPS WITH THE HELP OF LAKE MICHIGAN. THIS BOUNDARY COUPLED WITH THE VERY HUMID AIRMASS MAY TRIGGER ISOLD-SCT SHRA/TSRA THIS AFTERNOON INLAND OF THE LAKE WHICH WOULD THEN DRIFT BACK TOWARDS THE LAKE AFTER DEVELOPMENT. HAVE INCLUDED VCTS MENTION AT ORD/MDW/RFD/DPA WITH DECENT CONFIDENCE THAT ACTIVITY WILL OCCUR BUT WITH QUESTION MARKS SURROUNDING THE EXTENT. WINDS WILL DIMINISH THIS EVENING/TONIGHT WHICH MAY ALLOW SOME SHALLOW DENSE FOG OR MORE WIDESPREAD MVFR TYPE FOG. TSRA CHANCES REMAIN A CHALLENGE BUT HAVE PRETTY LOW CONFIDENCE IN WHEN THE BEST OPPORTUNITY WILL BE THIS EVENING THROUGH SATURDAY. WITH THE FRONTAL BOUNDARY EXPECTED TO BE IN THE REGION IT WOULD LIKELY SERVE AS A TRIGGER BUT IT MAY BE SOUTH OF THE AREA TONIGHT. UPPER RIDGING WILL BUILD IN SATURDAY WHICH WOULD BRING ANOTHER PUSH OF WARM AIR AND COUPLED WITH THE BOUNDARY WOULD PROBABLY DRIVE MORE TSRA DEVELOPMENT WHICH MAY BE FAVORED SATURDAY MORNING. WILL LEAVE THE TAF DRY BEYOND THIS AFTERNOON GIVEN THE UNCERTAINTY BUT HAVE DECENT CONFIDENCE THAT TSRA WILL OCCUR AT SOME POINT. MDB //ORD AND MDW CONFIDENCE...UPDATED 16Z... * LOW IN HOW LONG MVFR CIGS WILL PERSIST. * HIGH IN SW WINDS BECOMING NORTHEAST THIS AFTERNOON. MEDIUM IN SPEEDS UNDER 10 KT. LOW IN TIMING OF SHIFT TO NORTHEAST. * MEDIUM THAT THERE WILL BE SOME ISOLD SHRA/TSRA DEVELOPMENT THIS AFTERNOON. LOW IF THEY WILL OCCUR AT TERMINALS. * LOW IN TIMING OF BEST SHRA/TSRA CHANCES THIS EVENING THROUGH SATURDAY MORNING. MDB/MTF //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... * SATURDAY NIGHT THROUGH THURSDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. MDB && .MARINE... 349 AM CDT AN ELONGATED AREA OF LOW PRESSURE STRETCHES FROM SOUTHERN MINNESOTA INTO THE SOUTHERN PLAINS WITH A WEAK WARM FRONTAL BOUNDARY STRETCHING FROM NORTHERN INDIANA BACK INTO CENTRAL/NORTHERN IOWA. THIS FRONT WILL MOVE LITTLE INTO SATURDAY. MORNING STORMS HAVE CAUSED WINDS TO BE A BIT CHAOTIC ACROSS THE FAR SOUTHERN PART OF THE LAKE WHERE SOUTH TO SOUTHEAST WINDS WILL TURN MORE EAST AND NORTHEAST INTO THE AFTERNOON. LOW PRESSURE WILL ORGANIZE ACROSS THE CENTRAL AND NORTHERN PLAINS LATER SATURDAY AND MOVE TO WESTERN ONTARIO SUNDAY ALLOWING WINDS TO TURN SOUTHERLY AND INCREASE IN SPEED TOWARD MONDAY. THE LOW WILL THEN TRACK TO THE NORTHEAST EARLY NEXT WEEK DRAGGING A FRONTAL BOUNDARY SOUTHWARD WHICH MAY STALL OUT SOMEWHERE ACROSS THE LAKE ALLOWING FOR VARIABLE WINDS. ANOTHER LOW IS EXPECTED TO LIFT NORTHEAST MID WEEK BRINGING A STRONGER COLD FRONT ACROSS THE LAKE WHICH WOULD BRING A SHIFT TO NORTH AND NORTHWEST WINDS. STILL EARLY FOR DETAILS BUT THIS SCENARIO WOULD BRING A PERIOD OF STRONGER WIND SPEEDS THANKS TO COLD ADVECTION...NOT UNLIKE SIMILAR COLD FRONTAL PASSAGES WE HAVE SEEN THE PAST FEW WEEKS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ 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 NATIONAL WEATHER SERVICE LINCOLN IL 1038 AM CDT Fri Aug 22 2014 .UPDATE... ISSUED AT 1038 AM CDT FRI AUG 22 2014 Large cluster of thunderstorms that developed along an outflow boundary late last night continues to diminish as it pushes eastward across central Illinois this morning. 1530z radar imagery shows showers with a few embedded thunderstorms along/north of a Beardstown...to Decatur...to Paris line. High-res models suggest a continued weakening trend, with little or no precip remaining by mid-afternoon. Have adjusted PoPs to go categorical along/north of I-72 for the next couple of hours, followed by a decrease to just slight chance this afternoon. Have also lowered high temperatures by a few degrees across the central and northern zones where widespread clouds/rain have kept readings cooler than previously expected. Visible satellite imagery shows plenty of breaks developing upstream across Iowa, so have only dropped highs into the upper 80s. Further south where the rain has not occurred this morning, have maintained highs in the lower 90s. && .SHORT TERM...(Today and tonight) ISSUED AT 325 AM CDT FRI AUG 22 2014 07z/2am surface analysis shows a stationary front extending from west to east across northern Illinois. A 35kt LLJ has helped trigger a line of convection just south of that front. Those storms will affect our northern counties early this morning, with locally heavy rainfall rates possible. Areas near Midway airport last night picked up 3" in 30 minutes. There most likely will be a break in the rainfall for at least a few hours later this morning and early this afternoon, before the next shortwave over Iowa works its way into IL. Precipitable water values up near 2" will continue through the day, so any convection that redevelops this afternoon into evening will have the potential to produce very heavy rainfall. Coverage may not be too extensive during the day, so slight chance and low chance PoPs were used for areas north of I-72 after 7 am. The HRRR/NAM/GFS/ECMWF all show an enhanced opportunity for storms either later this afternoon or this evening as an MCS develops to our west and rolls across N IL. With timing still in question, we did not ramp up to likely PoPs in any one area even this evening and overnight. The main theme does seem to be that the northern half of the KILX CWA will be the main target area for storms over the next 24-36 hours. High temps today will once again climb into the upper 80s to low 90s, with dewpoints already in the mid 70s and likely to climb into the upper 70s in some areas. Heat index readings will likely climb to around 105 in southern areas. We can not rule out the possible need to expand the heat advisory northward. Precip and cloud cover across the north should keep their heat index readings below advisory levels in general. && .LONG TERM...(Saturday through Thursday) ISSUED AT 325 AM CDT FRI AUG 22 2014 Main issue through the extended remains the extreme heat for this time of year through the weekend and into the first portion of next week. Models still having issues with the ultimate breaking down of the ridge, resulting in a potential extension to the heat wave should the trend continue. Hot daytime highs into the 90s and dewpoints into the mid 70s resulting in heat indices over 100F for several days on end. Scattered chances exist as long as the boundary remains close to the FA...and will be the only chance for brief cool downs. But as the high builds into the region, the general subsidence will be hard to overcome, so the forecast for Saturday night through Sunday night is dry for now...with some slight chances coming back for Monday...but the models struggling with the solutions in the mid range with the timing of a vigorous wave to erode the ridge. GFS still far more aggressive, amplified, and fast with the passage of the upper trof/sfc front Tues night into Wednesday. ECMWF starting to close the gap and has abandoned the closed low of 24 hrs ago... but is still signif weaker, resulting in a developing baroclinic zone at the sfc as the wave fizzles in parallel flow and provides a focus for a longer duration potential for precip. Model blends now through the mid/end of next week results in more widespread chances. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 652 AM CDT FRI AUG 22 2014 A nocturnal LLJ has helped fuel an east-west line of storms across north-central IL. The storms with heavy rainfall will affect mainly PIA, BMI and CMI early this morning, bringing MVFR vis and ceilings. BMI has dropped to IFR cloud height, which could linger through 15z before lifting to MVFR. A break in the storms is indicated for the terminal sites for late morning into afternoon in the HRRR and RAP model output. Additional storm chances are indicated for later this afternoon and evening for the northern TAF sites of PIA, BMI and CMI. We kept precip our of DEC and SPI for now, but trends are for storms to get quite close even this morning. Will monitor closely for changes to the dry forecast for SPI/DEC. Winds will generally remain S-SW in the synoptic flow across our area, south of the warm front. Local northerly winds have developed for the northern terminals where the storms have produced an outflow boundary moving south. The outflow could even reach SPI and DEC, but wind speeds by then should be 10kt or less. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. && $$ UPDATE...BARNES SHORT TERM...SHIMON LONG TERM...HJS AVIATION...SHIMON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1253 PM CDT FRI AUG 22 2014 .UPDATE... SENDING UPDATE TO LOWER MAX TEMPS A BIT DUE TO LINGERING DEBRIS CLOUDINESS...WITH HIGHS MAINLY IN THE 80S. ALSO...UPDATED POPS TO BETTER REFLECT CURRENT TRENDS. && .PREV DISCUSSION... /ISSUED 328 AM CDT FRI AUG 22 2014/ SYNOPSIS... ISSUED AT 328 AM CDT FRI AUG 22 2014 ALOFT...UPPER RIDGE PERSISTS OVER THE MISSISSIPPI VALLEY. SURFACE LOW NEAR KLSE THIS MORNING WITH A STATIONARY FRONT EXTENDING TO ITS SOUTHWEST INTO COLORADO AND ALSO TO ITS EAST INTO THE GREAT LAKES. THUNDERSTORMS THIS MORNING FUELED BY LLJ...WARM SECTOR DEW POINTS IN THE 70S...AND APPROACHING MCV. SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 328 AM CDT FRI AUG 22 2014 AREA OF CONVECTION OVER SOUTH CENTRAL IOWA SHOULD PERSIST THROUGH SUNRISE AND AFFECT SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. SHORT RANGE MODELS INCLUDING THE HRRR AND RUC WEAKEN THE CONVECTION AFTER SUNRISE...WHICH MAKES SENSE GIVEN THE DIURNAL TREND OF THE LLJ. HOWEVER...MODELS HAVE TYPICALLY BEEN TOO QUICK TO SQUELCH CONVECTION...AND THUS BELIEVE IT WILL LINGER A BIT LONGER THAN PROGGED AND WILL HANG ON TO POPS IN THE SOUTHERN HALF OF THE CWFA LONGER THAN MESOSCALE MODELS WOULD SUGGEST. ANOTHER ROUND OF STORMS EXPECTED THIS AFTERNOON AS THE SURFACE LOW CONTINUES TO SAG EVER SO SLIGHTLY FARTHER SOUTH AND THE FRONT REMAINS STALLED OVER NRN MO/SRN IA. OF COURSE EXACT POSITIONING OF STORMS REMAINS UNCERTAIN...IN PARTICULAR WITH SO MANY BOUNDARIES AROUND. CURRENT THINKING IS THAT FAVORED AREA IS ALONG AND JUST SOUTH OF I80 WHERE THE 850 MB FRONT IS PROGGED TO SET UP. REGARDLESS OF EXACT LOCATION...EXPECT INTENSE RAINFALL RATES DUE TO HIGH PRECIPITABLE WATERS AT OR ABOVE 2 INCHES. ACTIVE WEATHER CONTINUES THROUGH TONIGHT WITH BOUNDARIES LINGERING AND POTENTIAL FOR UPPER WAVES COMING OUT OF THE WSW. LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 328 AM CDT FRI AUG 22 2014 THE PERSISTENT RING OF FIRE PATTERN CONTINUES THROUGH THE WEEKEND PRESENTING A THREAT FOR HOT AND HUMID CONDITIONS OUTSIDE THE OCCASIONAL MESOSCALE CONVECTIVE COMPLEXES LIKELY TO IMPACT PARTS OF THE REGION. THE UPPER LEVEL RIDGE IS THEN EXPECTED TO BREAK DOWN AND SHIFT EASTWARD BY THE MIDDLE PART OF NEXT WEEK. THIS WILL ALLOW CANADIAN HIGH PRESSURE TO BUILD INTO THE AREA...RETURNING TEMPERATURES CLOSER TO LATE AUGUST NORMALS AND PROVIDING A PERIOD OF DRIER WEATHER. SATURDAY AND SUNDAY...LOW PRESSURE LIFTING NORTHEAST THROUGH THE NORTHERN PLAINS WILL LIFT THE LOW LEVEL BOUNDARY/WARM FRONT NORTHWARD THROUGH THE FORECAST AREA SATURDAY. THE ASSOCIATED WARM ADVECTION AND STRENGTHENING MID LEVEL CAP WILL LIMIT THUNDERSTORM CHANCES TO THE NORTHEAST HALF OF THE FORECAST AREA. WITH DEW POINTS EASILY IN THE LOWER TO MID 70S...VERY MUGGY CONDITIONS WILL CONTINUE. MAX TEMPERATURES WILL CONTINUE TO BE A CHALLENGE DUE TO UNCERTAINTY IN CONVECTIVE TRENDS AND ASSOCIATED CLOUD COVER. WITH SURFACE WINDS MORE SOUTHEASTERLY...WILL BIAS TOWARD THE LOWER END OF GUIDANCE WITH HIGHS FROM THE MID 80S NORTHEAST TO LOWER 90S SOUTH. THIS WOULD STILL RESULT IN HEAT INDEX READINGS NEAR TO JUST ABOVE 100 SOUTH OF I-80 IN THE AFTERNOON HOURS. SATURDAY NIGHT THROUGH SUNDAY...THE AREA WILL FALL INTO THE MORE DEEPLY MIXED BUT CAPPED WARM SECTOR WITH 850 MB TEMPERATURES SUPPORTIVE OF WIDESPREAD HIGHS IN THE UPPER 80S TO LOWER 90S AND POSSIBLY WARMER DEPENDING ON THE AMOUNT OF CLOUD COVER. THIS WOULD RESULT IN POSSIBLY ANOTHER DAY OF 100 PLUS HEAT INDEX VALUES AND MAY REQUIRE HEAT HEADLINES OVER AT LEAST THE SOUTH. MONDAY THROUGH THURSDAY...MODEL SOLUTIONS CONTINUE TO DIFFER IN THE TIMING OF THE BOTH THE INITIAL EARLY WEEK FRONTAL PASSAGE AND THE STRONGER COLD FRONT AROUND WED AND THU. THE ECMWF AND CANADIAN HAVE THE INITIAL FRONT PUSHING THROUGH INTO CENTRAL IL AND MO MONDAY...WHILE THE GFS HOLDS IT WELL TO THE NW. OUR FORECAST WILL CONTINUE A LOW CONFIDENCE BLENDED APPROACH WITH THUNDERSTORM CHANCES RETURNING LATE MONDAY AND CONTINUING THROUGH THURSDAY. THE PAST COUPLE RUNS WERE TRENDING TOWARD A GREATER LIKELIHOOD OF A DRY THURSDAY AS HIGH PRESSURE BUILDS IN. WARM TO VERY WARM AND CONTINUED HIGH HUMIDITY SUGGEST A POSSIBLE NEED FOR HEAT HEADLINES AT LEAST IN THE AFTERNOON HOURS FOR MONDAY AND TUESDAY WHERE HIGHS ARE MAINTAINED IN THE UPPER 80S TO LOWER 90S WITH OVERNIGHT LOWS HOLDING IN THE 70S FOR MUCH OF THE AREA. TEMPERATURES ARE TRENDING A BIT COOLER...FOR WED AND THU AS THE CONTINUITY IN SUCCESSIVE MODEL RUNS BACK THE TIMING OF THE PATTERN CHANGE AND PLACEMENT OF THE IN-COMING HIGH. AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY MORNING) ISSUED AT 1253 PM CDT FRI AUG 22 2014 LIFR CONDITIONS AT KDBQ WILL SLOWLY IMPROVE TO MVFR BY SUNSET. OTHERWISE EXPECT VFR CONDITIONS THROUGH SUNSET WITH ISOLATED TSRA/SHRA POSSIBLE. AFT SUNSET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP...POSSIBLY IN SOUTHWEST IOWA. THIS THUNDERSTORM COMPLEX SHOULD MOVE EAST OR EAST SOUTHEAST THROUGH SUNRISE. CONDITIONS WILL SLOWLY DETERIORATE TO MVFR AND POSSIBLY IFR CONDITIONS AT KCID/KMLI/KBRL. KDBQ WILL DETERIORATE TO IFR AND POSSIBLY LIFR CONDITIONS WITH NEARBY SHOWERS POSSIBLE. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1132 AM CDT FRI AUG 22 2014 .UPDATE... SENDING UPDATE TO LOWER MAX TEMPS A BIT DUE TO LINGERING DEBRIS CLOUDINESS...WITH HIGHS MAINLY IN THE 80S. ALSO...UPDATED POPS TO BETTER REFLECT CURRENT TRENDS. && .PREV DISCUSSION... /ISSUED 328 AM CDT FRI AUG 22 2014/ SYNOPSIS... ISSUED AT 328 AM CDT FRI AUG 22 2014 ALOFT...UPPER RIDGE PERSISTS OVER THE MISSISSIPPI VALLEY. SURFACE LOW NEAR KLSE THIS MORNING WITH A STATIONARY FRONT EXTENDING TO ITS SOUTHWEST INTO COLORADO AND ALSO TO ITS EAST INTO THE GREAT LAKES. THUNDERSTORMS THIS MORNING FUELED BY LLJ...WARM SECTOR DEW POINTS IN THE 70S...AND APPROACHING MCV. SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 328 AM CDT FRI AUG 22 2014 AREA OF CONVECTION OVER SOUTH CENTRAL IOWA SHOULD PERSIST THROUGH SUNRISE AND AFFECT SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. SHORT RANGE MODELS INCLUDING THE HRRR AND RUC WEAKEN THE CONVECTION AFTER SUNRISE...WHICH MAKES SENSE GIVEN THE DIURNAL TREND OF THE LLJ. HOWEVER...MODELS HAVE TYPICALLY BEEN TOO QUICK TO SQUELCH CONVECTION...AND THUS BELIEVE IT WILL LINGER A BIT LONGER THAN PROGGED AND WILL HANG ON TO POPS IN THE SOUTHERN HALF OF THE CWFA LONGER THAN MESOSCALE MODELS WOULD SUGGEST. ANOTHER ROUND OF STORMS EXPECTED THIS AFTERNOON AS THE SURFACE LOW CONTINUES TO SAG EVER SO SLIGHTLY FARTHER SOUTH AND THE FRONT REMAINS STALLED OVER NRN MO/SRN IA. OF COURSE EXACT POSITIONING OF STORMS REMAINS UNCERTAIN...IN PARTICULAR WITH SO MANY BOUNDARIES AROUND. CURRENT THINKING IS THAT FAVORED AREA IS ALONG AND JUST SOUTH OF I80 WHERE THE 850 MB FRONT IS PROGGED TO SET UP. REGARDLESS OF EXACT LOCATION...EXPECT INTENSE RAINFALL RATES DUE TO HIGH PRECIPITABLE WATERS AT OR ABOVE 2 INCHES. ACTIVE WEATHER CONTINUES THROUGH TONIGHT WITH BOUNDARIES LINGERING AND POTENTIAL FOR UPPER WAVES COMING OUT OF THE WSW. LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 328 AM CDT FRI AUG 22 2014 THE PERSISTENT RING OF FIRE PATTERN CONTINUES THROUGH THE WEEKEND PRESENTING A THREAT FOR HOT AND HUMID CONDITIONS OUTSIDE THE OCCASIONAL MESOSCALE CONVECTIVE COMPLEXES LIKELY TO IMPACT PARTS OF THE REGION. THE UPPER LEVEL RIDGE IS THEN EXPECTED TO BREAK DOWN AND SHIFT EASTWARD BY THE MIDDLE PART OF NEXT WEEK. THIS WILL ALLOW CANADIAN HIGH PRESSURE TO BUILD INTO THE AREA...RETURNING TEMPERATURES CLOSER TO LATE AUGUST NORMALS AND PROVIDING A PERIOD OF DRIER WEATHER. SATURDAY AND SUNDAY...LOW PRESSURE LIFTING NORTHEAST THROUGH THE NORTHERN PLAINS WILL LIFT THE LOW LEVEL BOUNDARY/WARM FRONT NORTHWARD THROUGH THE FORECAST AREA SATURDAY. THE ASSOCIATED WARM ADVECTION AND STRENGTHENING MID LEVEL CAP WILL LIMIT THUNDERSTORM CHANCES TO THE NORTHEAST HALF OF THE FORECAST AREA. WITH DEW POINTS EASILY IN THE LOWER TO MID 70S...VERY MUGGY CONDITIONS WILL CONTINUE. MAX TEMPERATURES WILL CONTINUE TO BE A CHALLENGE DUE TO UNCERTAINTY IN CONVECTIVE TRENDS AND ASSOCIATED CLOUD COVER. WITH SURFACE WINDS MORE SOUTHEASTERLY...WILL BIAS TOWARD THE LOWER END OF GUIDANCE WITH HIGHS FROM THE MID 80S NORTHEAST TO LOWER 90S SOUTH. THIS WOULD STILL RESULT IN HEAT INDEX READINGS NEAR TO JUST ABOVE 100 SOUTH OF I-80 IN THE AFTERNOON HOURS. SATURDAY NIGHT THROUGH SUNDAY...THE AREA WILL FALL INTO THE MORE DEEPLY MIXED BUT CAPPED WARM SECTOR WITH 850 MB TEMPERATURES SUPPORTIVE OF WIDESPREAD HIGHS IN THE UPPER 80S TO LOWER 90S AND POSSIBLY WARMER DEPENDING ON THE AMOUNT OF CLOUD COVER. THIS WOULD RESULT IN POSSIBLY ANOTHER DAY OF 100 PLUS HEAT INDEX VALUES AND MAY REQUIRE HEAT HEADLINES OVER AT LEAST THE SOUTH. MONDAY THROUGH THURSDAY...MODEL SOLUTIONS CONTINUE TO DIFFER IN THE TIMING OF THE BOTH THE INITIAL EARLY WEEK FRONTAL PASSAGE AND THE STRONGER COLD FRONT AROUND WED AND THU. THE ECMWF AND CANADIAN HAVE THE INITIAL FRONT PUSHING THROUGH INTO CENTRAL IL AND MO MONDAY...WHILE THE GFS HOLDS IT WELL TO THE NW. OUR FORECAST WILL CONTINUE A LOW CONFIDENCE BLENDED APPROACH WITH THUNDERSTORM CHANCES RETURNING LATE MONDAY AND CONTINUING THROUGH THURSDAY. THE PAST COUPLE RUNS WERE TRENDING TOWARD A GREATER LIKELIHOOD OF A DRY THURSDAY AS HIGH PRESSURE BUILDS IN. WARM TO VERY WARM AND CONTINUED HIGH HUMIDITY SUGGEST A POSSIBLE NEED FOR HEAT HEADLINES AT LEAST IN THE AFTERNOON HOURS FOR MONDAY AND TUESDAY WHERE HIGHS ARE MAINTAINED IN THE UPPER 80S TO LOWER 90S WITH OVERNIGHT LOWS HOLDING IN THE 70S FOR MUCH OF THE AREA. TEMPERATURES ARE TRENDING A BIT COOLER...FOR WED AND THU AS THE CONTINUITY IN SUCCESSIVE MODEL RUNS BACK THE TIMING OF THE PATTERN CHANGE AND PLACEMENT OF THE IN-COMING HIGH. AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 627 AM CDT FRI AUG 22 2014 PATCHY DENSE FOG AFFECTING KCID AND KDBQ WILL LIFT BY MID MORNING. MEANWHILE...THUNDERSTORMS WILL AFFECT KBRL THIS MORNING AND SHOWERS WILL MOVE INTO KMLI. LATER TODAY...ANOTHER ROUND OF STORMS IS POSSIBLE THIS AFTERNOON AND EVENING AT ALL AREA TAF SITES...BUT THE GREATEST CHANCE IS FOR AREAS MAINLY SOUTH OF I 80. OTHERWISE...PREVAILING WINDS WILL BE LIGHT AND VARIABLE WITH GUSTS NEAR THUNDERSTORMS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 05
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
335 PM EDT FRI AUG 22 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 335 PM EDT FRI AUG 22 2014 18Z SFC ANALYSIS SHOWS A CONVECTIVELY WASHED OUT BOUNDARY JUST NORTH OF THE OHIO RIVER. THIS LEADS BACK WEST TO A DEVELOPING AREA OF LOW PRESSURE OVER THE HIGH PLAINS. MEANWHILE...AN AREA OF HIGH PRESSURE IS FOUND THROUGH THE DEEP SOUTH. ALOFT...A FAIRLY STRONG RIDGE OF HIGH HEIGHTS STRETCHES FROM THE SOUTHERN PLAINS THROUGH THE LOWER MISSISSIPPI RIVER VALLEY AND ACROSS THE DEEP SOUTH WHILE TROUGHING IS FOUND OVER NEW ENGLAND. BETWEEN THESE UPPER LEVEL FEATURES...A COUPLE OF SHORTWAVES ARE PASSING BY TO THE NORTHEAST. THE LEADING ONE OF THESE IS RESPONSIBLE FOR BETTER DEVELOPMENT OF CONVECTION OVER FAR EASTERN KENTUCKY AND WESTERN WEST VIRGINIA. ELSEWHERE...TO THE WEST OF THIS AREA...A FEW SCATTERED SHOWERS AND THUNDERSTORMS ARE TAKING SHAPE ALONG AN OLD OUTFLOW BOUNDARY FROM THE PRE DAWN MCS THAT MOVED THROUGH OHIO EARLY THIS MORNING. WITH THE BULK OF THE ACTIVITY HOLDING OFF UNTIL LATER IN THE AFTERNOON...TEMPERATURES HAVE CLIMBED INTO THE UPPER 80S FOR MOST LOCATIONS WITH A FEW 90 DEGREE READINGS NOTED. DEWPOINTS IN THE LOWER AND MIDDLE 70S ARE MAKING FOR MISERABLE HEAT INDICES THROUGH THE AREA AND WILL BE PROVIDING FUEL FOR STORM DEVELOPMENT. WINDS ARE GENERALLY FROM THE WEST SOUTHWEST AT 5 TO 10 KTS WITH A FEW GUSTS TO 15 KTS. THE MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM ALOFT AS THEY ALL WOBBLE AND WEAKEN SLIGHTLY THE RIDGE TO OUR WEST IN THE FACE OF THE NEW ENGLAND TROUGH DROPPING NEARLY DUE SOUTH TO THE MID ATLANTIC COAST BY SUNDAY MORNING. DESPITE THE MOVEMENT OF THESE LARGER FEATURES...THE TRACK OF SHORTWAVES WILL CONTINUE TO PASS THROUGH FAR EASTERN KENTUCKY...JUST ORIENTATED MORE NORTH TO SOUTH BY THE END OF THE PERIOD. GIVEN THE MODEL AGREEMENT AND THE SMALLER SCALE NATURE OF THE PERIODIC MCS ACTIVITY HAVE FAVORED THE HIGHER RESOLUTION MODELS LIKE THE HRRR AND NAM12 FOR THIS FORECAST. SENSIBLE WEATHER WILL FEATURE A THREAT OF STORMS INTO THE EVENING... PERHAPS LENGTHENED BY ANY DEVELOPMENT TO THE NORTHWEST THAT COULD MOVE INTO AT LEAST THE NORTHWEST PORTION OF THE JKL CWA AFTER DARK... PER THE LATEST HRRR. SIMILAR TO LAST EVENING...THE MAIN THREATS WITH ANY STORMS WILL BE GUSTY WINDS AND TORRENTIAL DOWNPOURS OF RAIN. AGAIN TONIGHT...WOULD ANTICIPATE PATCHY FOG THROUGH THE AREA AND THE POTENTIAL FOR DENSE SPOTS LOCALLY GIVEN ANY CLEARING. AFTER A MUGGY NIGHT...ANOTHER WARM AND HUMID DAY CAN BE EXPECTED FOR SATURDAY WITH MID LEVEL CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE ENTIRETY WITH ONLY A SLIGHT FAVORING OF THE LATE AFTERNOON AND EARLY EVENING HOURS. HIGH PWS AND INSTABILITY DURING THE DAY WILL SET THE TABLE FOR A CONTINUED THREAT OF EXCESSIVE RAINFALL AND STRONG STORMS...THOUGH THE SEVERE RISK WILL BE LIMITED BY A GENERALLY BENIGN NORTHWEST WIND FIELD ALOFT. SIMILARLY...SATURDAY NIGHT WILL BE ANOTHER MUGGY AND WARM ONE WITH PATCHY FOG ANTICIPATED FOR PLACES THAT WOULD HAVE SEEN RAIN DURING THE DAY. CANNOT RULE OUT ADDITIONAL SHOWER AND STORM ACTIVITY INTO EARLY SUNDAY GIVEN THE UPPER LEVEL PATTERN AND NEARBY SFC BOUNDARIES. AGAIN USED THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SATURDAY NIGHT. AS FOR POPS...ENDED UP IN BETWEEN THE MAV AND THE WETTER MET GUIDANCE FOR MOST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 255 PM EDT FRI AUG 22 2014 STRONG RIDGING WILL CONTINUE TO DEVELOP OVER THE EASTERN CONUS LATE IN THE WEEKEND THROUGH THE EARLY PART OF NEXT WEEK. AS THE CENTER OF THE HIGH PUSHES OVERHEAD EARLY NEXT WEEK...IT WILL SEND SOME SLIGHTLY DRIER AIR INTO EASTERN KENTUCKY...FINALLY BRINGING A TEMPORARY END TO THE RAIN CHANCES. HAVE BEEN GOING WITH LOW POPS EARLY NEXT WEEK...BUT GIVEN THE NATURE OF THE DRY AIR...HAVE OPTED TO GO WITH DRY WEATHER EARLY TO MIDDLE PART OF NEXT WEEK. IN FACT...DEWPOINTS MAY GET LOW ENOUGH TO WARRANT A FEW TEMPERATURES INTO THE LOWER AND MIDDLE 60S TUESDAY AND WEDNESDAY MORNINGS. CANNOT RULE OUT SOME SHOWERS ON SUNDAY OR SUNDAY EVENING PRIOR TO THE DEPARTURE OF THE BETTER MID LEVEL MOISTURE. HOWEVER...EVEN THIS ACTIVITY WILL LIKELY BE LESS THAN WHAT WE HAVE SEEN RECENTLY. THUS...OVERALL...LOOK FOR A QUIETER STRETCH OF WEATHER INTO THE MIDDLE OF NEXT WEEK. BY LATE IN THE PERIOD. THE RIDGE MAY BEGIN TO BREAK DOWN AS A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES PUSHES A BOUNDARY SOUTHWARD INTO THE OHIO RIVER VALLEY. TOO MUCH UNCERTAINTY WITH THIS BOUNDARY TO GO WITH ANYTHING MORE THAN CHANCE POPS FROM THURSDAY ONWARD. THE 00Z ECMWF HAD PUT THE BOUNDARY OVER EASTERN KENTUCKY...BUT THE 12Z RUN HAS KEPT IT TO THE NORTH THROUGH WEEKS END. IF THE BOUNDARY STAYS NORTH...PROBABLY GOING TO SEE WARMER AND HUMID CONDITIONS PERSISTING THROUGH THE SECOND HALF OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 200 PM EDT FRI AUG 22 2014 STILL AWAITING DEVELOPMENT OF STORMS THROUGH EAST KENTUCKY THIS AFTERNOON. WITHOUT A CLEAR INDICATION OF WHERE THEY WILL BE POPPING AND AFFECTING THE TAF SITES HAVE LEFT THEM WITH VCTS THROUGH THE REST OF THE DAY AND INTO THE EVENING BEFORE BACKING OFF TO JUST SOME VCSH AND LIGHT FOG LATER TONIGHT. WITH THE HIGH LEVEL OF MOISTURE OUT THERE SOME OF THE DECKS OF CLOUDS HAVE COME IN RATHER LOW FOR THE MIDDLE OF THE DAY...ESPECIALLY IN THE NORTHEAST PARTS OF THE AREA. EXPECT THIS TO BE THE CASE INTERMITTENTLY THROUGH THE FIRST PART OF THE EVENING AND ALSO WITH ANY STORM...HOWEVER...MUCH OF THE TIME AT THE SITES CIGS WILL BE VFR IF THERE AT ALL. A SIMILAR SET UP FOR TOMORROW WILL CONTINUE THE THREAT OF SHOWERS AND STORMS THROUGH THE DAY WITH A POTENTIAL FOR MVFR CIGS AND VIS WITH ANY CONVECTION. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE EXPECT DURING PEAK HEATING WHEN SOME MAINLY WESTERLY BREEZES WILL TOP OUT BETWEEN 5 AND 10 KTS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
200 PM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 140 PM EDT FRI AUG 22 2014 STORMS ARE STARTING TO POP OVER WESTERN WEST VIRGINIA IN ADDITION TO HINTS THAT SOME ARE STARTING TO FORM ALONG A WELL DEFINED OUTFLOW BOUNDARY DRIFTING SOUTH THROUGH CENTRAL AND PARTS OF EASTERN KENTUCKY. THE RAP MODEL IS STILL ON TRACK WITH EXPECTED DEVELOPMENTS OVER NORTHEASTERN PARTS OF THE AREA BUILDING SOUTH WITH TIME. HAVE MADE ONLY MINOR ADJUSTMENTS TO THE EXISTING FORECAST...PRIMARILY TO FINE TUNE POPS AND SKY COVER OVER THE NEXT FEW HOURS...IN ADDITION TO TWEAKING TEMPS AND DEWPOINTS PER THE LATEST OBS AND TRENDS. THESE FRESHENED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 1200 PM EDT FRI AUG 22 2014 15Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE THROUGH THE DEEP SOUTH WITH GENERAL LOW PRESSURE TO THE NORTH AND WEST OF THIS AREA. THIS PLACES EAST KENTUCKY ON THE NORTHERN FRINGE OF THE SFC RIDGE AND ALSO THE NORTHEAST EDGE OF THE MID LEVEL ONE PARKED TO THE SOUTHWEST OF THE AREA. THE STORM TRACK...LIKE THOSE PAST COUPLE OF DAYS...IS PRETTY CLEAR AS CONVECTIVE CLUSTERS DEVELOP IN NORTHERN ILLINOIS AND INDIANA...ROLLING SOUTHEAST INTO OHIO BEFORE HITTING THE APPALACHIANS AT WEST VIRGINIA. THE BEST INSTABILITY REMAINS TO THE SOUTH AND WEST OF THIS TRACK...LEADING TO A TENDENCY FOR THESE SYSTEMS TO ARC TO THE SOUTH INTO EASTERN KENTUCKY OR KICKING OFF OUTFLOW BOUNDARIES STRONG ENOUGH TO INITIATE NEW DEVELOPMENT. THE LATEST HIGH RESOLUTION NEAR TERM MODELS INCLUDING THE HRRR AND 12Z NAM12 SUGGEST THAT BOTH SCENARIOS ARE POSSIBLE THIS AFTERNOON WITH THE FORMER FOCUSING ON SCATTERED DEVELOPMENT THROUGH THE CWA AFTER 18Z AND PERHAPS A MORE ORGANIZED SYSTEM ARRIVING FROM THE NORTHWEST AFTER 21Z. THE NAM12 FOCUSES ON THE NORTHWEST SYSTEM AND HAS IT PUSH INTO EAST KENTUCKY BETWEEN 18 AND 21Z WITH LESS AIR MASS CONVECTION AHEAD OF IT. ALOFT...THE GENESIS WAVE APPEARS TO PASS THROUGH THE SOUTHERN OHIO VALLEY BY 21Z SO THE NAM12 WITH ITS EARLIER ARRIVAL APPEARS TO BE REASONABLE. HIGH PWS AGAIN TODAY ALONG WITH GOOD INSTABILITY SUGGEST THE POTENTIAL FOR FLASH FLOODING...ESPECIALLY FOR PLACES THAT SEE TRAINING...ALONG WITH STRONG TO MARGINALLY SEVERE STORMS WITH DAMAGING WIND GUSTS AS THE MAIN THREAT. HAVE UPDATED TO CONVEY THIS IN THE SKY...POP...QPF...AND WX GRIDS. EAST KENTUCKY WILL ALSO HAVE A CONTINUANCE OF THE HOT AND HUMID CONDITIONS WITH HIGHS AROUND 90...SUBJECT TO THUNDERSTORM INDUCED COOL DOWNS...AND DEWPOINTS IN THE STEAMY LOW TO MID 70S. A NEW SET OF ZONES WERE ISSUED TO REFLECT THE ABOVE AND THE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 810 AM EDT FRI AUG 22 2014 THE FORECAST REMAINS ON TRACK THIS MORNING. SHOWERS AND THUNDERSTORMS WILL LIKELY STEER CLEAR OF THE AREA UNTIL MAINLY THIS AFTERNOON. FRESHENED UP THE SKY COVER AND HOURLY TEMPERATURES AND DEW POINTS TO ALIGN BETTER WITH THE LATEST TRENDS IN OBSERVATIONS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 400 AM EDT FRI AUG 22 2014 THE LATEST SURFACE MAP FEATURES SURFACE HIGH PRESSURE ACROSS THE GULF COAST STATES...WITH BROADENING LOW PRESSURE ACROSS THE PLAINS. A STATIONARY FRONTAL BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO VALLEY. ALOFT...AN UPPER LEVEL RIDGE IS CURRENTLY CENTERED NEAR LOUISIANA WITH ITS INFLUENCE EXTENDING FURTHER NORTH INTO THE MISSISSIPPI VALLEY. TROUGHING REMAINS POISED ACROSS THE WESTERN CONUS. THUNDERSTORM COMPLEXES CONTINUE TO GEN UP ON THE NORTHERN PERIPHERY OF THE RIDGE AXIS AND THEN PROCEED TO ADVANCE ESE ACROSS THE OHIO VALLEY. CURRENTLY...A WEAKENING COMPLEX IS SKIRTING NORTHEASTERN KENTUCKY...LIKELY CLEARING OUR FORECAST AREA IN THE NEXT 2 TO 3 HOURS. THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...WITH THE UPPER LEVEL RIDGE GRADUALLY AMPLIFYING ACROSS THE MISSISSIPPI VALLEY. DETAILS ASSOCIATED WITH CONVECTIVE INITIATION CONTINUE TO BE PROBLEMATIC HOWEVER...AND HAVE STUCK WITH A GENERAL MODEL BLEND...WHICH FAVORS MORE VIGOROUS CONVECTION DURING THE WARMER PART OF THE DAY. TODAY LOOKS TO BE SOMEWHAT OF A REPEAT OF YESTERDAY...WITH STOUT INSTABILITY BUILDING BY EARLY THIS AFTERNOON. WHILE THE MCS TRACK HAS SHIFTED A BIT FURTHER NORTHEAST TODAY COMPARED TO YESTERDAY...OUTFLOW BOUNDARIES CONTINUE TO BE THE MAIN PLAYER...LEAVING MOST LOCATIONS IN THE LINE OF FIRE AT SOME POINT. SOME SEVERE THUNDERSTORMS CAN NOT BE RULED OUT ONCE AGAIN TODAY...ALONG WITH ISOLATED FLASH FLOODING...WHERE STORMS CAN ALIGN ALONG OUTFLOW BOUNDARIES PARALLEL TO THE STEERING FLOW. ANOTHER HOT AND HUMID DAY LOOKS TO BE ON TAP...WITH A FEW SPOTS NEARING THE 100 DEGREE MARK IN HEAT INDICES. STORMS WILL GRADUALLY WEAKEN INTO THE EVENING HOURS...ALTHOUGH SOME NOCTURNAL ACTIVITY REMAINS AT LEAST SOMEWHAT OF A POSSIBILITY. LOWS WILL BE MUGGY ONCE AGAIN AROUND THE 70 DEGREE MARK. SATURDAY WILL FEATURE ANOTHER WARM AND HUMID DAY...ALONG WITH THE THREAT OF MORE SCATTERED CONVECTION ACROSS THE AREA. THERE WILL BE LESS INSTABILITY AVAILABLE AS MID-LEVEL WARMING TAKES PLACE FROM THE INFLUENCE OF THE UPPER RIDGE. THIS WILL KEEP THE SEVERE AND FLASH FLOOD THREAT LOWER. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 400 AM EDT FRI AUG 22 2014 UPPER LEVEL RIDGING WILL REMAIN IN PLAY DURING THE DURATION OF THE EXTENDED...WITH HEIGHTS EXPECTED TO BUILD AS THE HIGH SHIFTS NEWARD ACROSS THE OHIO RIVER VALLEY. BUILDING HEIGHTS WILL THEN TRANSLATE TO RISING TEMPERATURES. HOWEVER...MID AND UPPER LEVEL WINDS WILL GENERALLY REMAIN OUT OF THE NORTH DURING THE FIRST FEW DAYS OF THE EXTENDED. THIS...COUPLED WITH CLOUD COVER THAT WILL HAMPER MAXIMUM SOLAR RADIATION...WILL KEEP HIGHS IN THE MID AND UPPER 80S THROUGH TUESDAY. TEMPS MAY THEN COOL DOWN A COUPLE DEGREES AFTER TUESDAY AS HIGH PRESSURE SITS OVERHEAD AND UPPER LEVEL HEIGHTS ASSOCIATED WITH THE RIDGE BECOME MORE STATIC. BASED ON THE LATEST FORECAST SOUNDINGS...WILL AGREE WITH PREVIOUS FORECAST THAT EACH DAY SHOULD POSE A SHOWER/THUNDERSTORM THREAT MAINLY IN THE AFTERNOON AND EVENING. GIVEN THE MID LEVEL DRYING FROM MONDAY ON...WOULDN/T BE SURPRISED IF SOME OF THESE STORMS PRODUCE SOME POTENTIAL HAIL. IN PROMISING NEWS...WITH THE RIDGING PATTERN IN PLACE...WE WILL EXPERIENCE NO BOUNDARY FORCING UNTIL VERY LATE IN THE FORECAST...SO THIS WILL HAMPER SOME OF THE BEST INSTABILITY AND WIDESPREAD INITIATION. WINDS WILL BE LIGHT AT THE SURFACE...AND REMAIN SO AS WE HEAD UP HIGHER INTO THE ATMOSPHERE. THAT BEING SAID...AFTERNOON CAPE VALUES WILL BE ABOVE THE 2K J/KG RANGE THROUGH MUCH OF THE EXTENDED...AND LAPSE RATES WILL RISE SLIGHTLY BY TUES/WED TO 6 TO 6.5 C/KM...SO AFTERNOON HEATING AND INSTABILITY MAY BE ALL THAT IS NECESSARY FOR SCATTERED CELL DEVELOPMENT EACH DAY. A BOUNDARY WILL FINALLY PUSH INTO THE AREA BY THURS/FRI DAY 7/8 /PER THE LATEST GFS MODEL RUN/. THIS WILL BRING A MORE WIDESPREAD CHANCE FOR RAIN AND THUNDERSTORMS ACROSS THE AREA. HOWEVER...THERE IS QUITE A BIT OF DISAGREEMENT IN THE EXTENDED MODELS THIS FAR OUT...SO DECIDED TO LEAN ON THE ALLBLEND FOR POPS AT THIS TIME. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 200 PM EDT FRI AUG 22 2014 STILL AWAITING DEVELOPMENT OF STORMS THROUGH EAST KENTUCKY THIS AFTERNOON. WITHOUT A CLEAR INDICATION OF WHERE THEY WILL BE POPPING AND AFFECTING THE TAF SITES HAVE LEFT THEM WITH VCTS THROUGH THE REST OF THE DAY AND INTO THE EVENING BEFORE BACKING OFF TO JUST SOME VCSH AND LIGHT FOG LATER TONIGHT. WITH THE HIGH LEVEL OF MOISTURE OUT THERE SOME OF THE DECKS OF CLOUDS HAVE COME IN RATHER LOW FOR THE MIDDLE OF THE DAY...ESPECIALLY IN THE NORTHEAST PARTS OF THE AREA. EXPECT THIS TO BE THE CASE INTERMITTENTLY THROUGH THE FIRST PART OF THE EVENING AND ALSO WITH ANY STORM...HOWEVER...MUCH OF THE TIME AT THE SITES CIGS WILL BE VFR IF THERE AT ALL. A SIMILAR SET UP FOR TOMORROW WILL CONTINUE THE THREAT OF SHOWERS AND STORMS THROUGH THE DAY WITH A POTENTIAL FOR MVFR CIGS AND VIS WITH ANY CONVECTION. WINDS THROUGH THE PERIOD WILL BE LIGHT AND VARIABLE EXPECT DURING PEAK HEATING WHEN SOME MAINLY WESTERLY BREEZES WILL TOP OUT BETWEEN 5 AND 10 KTS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...JMW AVIATION...GREIF
UPDATED FOR NEW AVIATION FORECAST DISCUSSION BELOW.

UPDATE ISSUED AT 959 AM CDT FRI AUG 22 2014 ADDED PATCHY DRIZZLE TO THE FORECAST THROUGH THE DAY AND KEPT FOG...LOCALLY DENSE MENTIONED THROUGH THE AFTERNOON AROUND THE TWIN PORTS...ESPECIALLY ALONG THE HILLSIDE AREA. LAKE BREEZE OFF LS WILL CONTINUE TODAY AND INTO THE WEEKEND WITH COOL TEMPERATURES...LOW CLOUDS AND PATCHY FOG AND DZ. REST OF THE FORECAST LOOKS ON TRACK AT THIS TIME. UPDATE ISSUED AT 650 AM CDT FRI AUG 22 2014 UPDATED AVIATION SECTION BELOW. && .SYNOPSIS... ISSUED AT 308 AM CDT FRI AUG 22 2014 MID LVL RIDGING CONTINUES OVER THE CWA EARLY THIS MORNING AS A BROAD AREA OF WEAK LOW PRESSURE SHIFTS SLOW EAST UNDERNEATH. LATEST RUC SHOWS A 925 LOW OVER WCTRL WISC WITH AN INVERTED SHEAR AXIS EXTENDING NORTHWEST TOWARDS KBJI AND KROX. THIS IS FOLLOWED BY A COLD FRONT STRETCHING FROM ERN MANITOBA SOUTH TO CENTRAL SODAK. MAIN STORY OVER CWA THIS MORNING IS TRAPPED MOIST LAYER... ABOUT 5K FT IN DEPTH...UNDERNEATH SUBSIDENCE INVERSION. BR/FG AND EVEN SOME DRIZZLE IS OCCURRING IN MANY AREAS. A FEW CONVECTIVE CELLS HAVE TRIED TO DEVELOP OVER SERN WISC ZONES IN AN AREA OF LOW LVL THETAE RIDGE AXIS. LIMITED INSTABILITY HAS ALLOWED FAIRLY SHORT TEMPORAL NATURE TO DEVELOPMENT. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 TODAY...FCST MDL SNDGS SUGGEST IT MAY TAKE QUITE SOME TIME TO DISSIPATE THE CANOPY OF STRATUS AND BR ACROSS THE REGION. COND PRES DEFICITS SHOW A TREND TO DIMINISHING BR BY 14/15Z....THEN A RELATIVELY SATURATED CLOUD LAYER FINALLY BREAKING AFTER 2PM. PRECIP CHC SEEMS QUITE LIMITED BY RIDGING ALOFT AND LACK OF LOW LVL FOCUS FOR CONVERGENCE. THE GREATEST OPPORTUNITY MAY ARISE IN THE AFTERNOON AHEAD OF APPROACHING FRONTAL BDRY PUSHING TOWARDS NWRN CWA. MID LVL WARMTH WILL LIMIT MUCH DEVELOPMENT UNTIL AFTERNOON AS 70H THERMAL COOLING COMMENCES OVER WRN CWA. TONIGHT...MID LVL RIDGE AMPLIFIES OVERHEAD TONIGHT IN RESPONSE TO UPSTREAM STRENGTHENING OF TROF OVER ROCKIES. FRONTAL BDRY WILL STALL NORTH AND WEST OF CWA HOWEVER ITS ASSOCIATED PREFRONTAL THETAE RIDGE WILL BE NEARBY. ALTHOUGH THE DRY FORECAST WAS CARRIED OVER FROM PREVIOUS FCSTR...WILL NEED TO WATCH FOR SOME DEVELOPMENT OF CONVECTION MAKING IT INTO NWRN CWA TONIGHT. TOMORROW...HEIGHT FALLS MOVE INTO WRN HIGH PLAINS WITH SFC LOW ORGANIZING OVER SODAK. A SWRLY MID LVL FLOW WILL BEGIN OVER THE CWA AS THE RIDGE AXIS SHIFTS EAST. SFC HIGH PRESSURE WILL INCREASE OVER LAKE SUPERIOR WITH DISTINCT ONSHORE COMPONENT TO BDRY LYR WIND. TOUGH FCST FOR PRECIP AS MAIN FOCUS APPEARS TO BE SHAPING UP OVER THE WRN CWA BY LATE IN THE DAY. CLOUDS/PRECIP FCST FOR NORTH SHORE BASED ON A COMBINATION OF TERRAIN LIFT AND A GRADUAL DEEPENING OF SYNOPTIC SCALE MOIST LAYER. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 308 AM CDT FRI AUG 22 2014 THE STRONG SURFACE LOW WILL MOVE NORTH ALONG THE WESTERN MINNESOTA BORDER SATURDAY NIGHT AND SUNDAY MORNING...BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...MAINLY THE THE WESTERN PORTIONS OF THE FORECAST AREA OVERNIGHT. HAVE GONE AHEAD AN INCREASED POPS TO CATEGORICAL THERE...WITH HIGH END CHANCE TO LIKELY POPS ELSEWHERE AS THE WARM FRONT MOVES NORTH ACROSS THE REGION. MODELS ARE GETTING CLOSE ENOUGH TOGETHER TO HAVE A FAIRLY HIGH CONFIDENCE...THOUGH THE TRACK IS STILL SOMEWHAT PROBLEMATIC. WITH THE SURFACE LOW MOVING NORTHEAST OF THE REGION SUNDAY AND SUNDAY NIGHT....A COLD FRONT IS DRAGGED THROUGH THE AREA. DEPENDING ON THE MODEL...THE TIMING DIFFERS...BUT EITHER WAY WE ARE LOOKING AT MORE CHANCE TO LIKELY POPS. THE ECMWF...WHICH IS FARTHER WEST THAN THE GFS IMPLIES WE MAY HAVE SOME POTENTIAL FOR SEVERE STORMS...AS THE FRONT COMES THROUGH LATER AND ALLOWS FOR HEATING DURING THE DAY TO BUILD INSTABILITY AHEAD OF IT. WILL HAVE TO WATCH THIS CAREFULLY IN THE NEXT FEW DAYS. HAVE GONE WITH SOME FAIRLY WARM HIGH TEMPS ON SUNDAY...BUT IF THE ECMWF WORKS OUT...THESE WILL NEED TO BE RAISED. THIS STORM LINGERS OVER WESTERN ONTARIO FOR MONDAY BEFORE MOVING OFF TO THE NORTHEAST MONDAY AFTERNOON AND NIGHT...KEEPING SOME CHANCE POPS GOING OVER THE AREA BOTH PERIODS WITH COOLER TEMPERATURES. OUR NEXT SIGNIFICANT STORM SYSTEM COMES BY ON TUESDAY THROUGH WEDNESDAY. MODELS ARE VARYING SIGNIFICANTLY BY THIS POINT...WITH THE THE GFS BRINGING AN AREA OF MODERATE TO HEAVY RAIN ACROSS THE FORECAST AREA...AND THE ECMWF KEEPING IT FARTHER SOUTH AND DRIER FOR US. FOR NOW HAVE GONE WITH A BLEND APPROACH WITH SOME CHANCE POPS AND WE WILL HAVE TO REVISIT WITH LATER FORECASTS. A STRONG SURFACE RIDGE BUILDS INTO THE AREA FOR WEDNESDAY NIGHT AND THURSDAY....BRINGING COOLER TEMPERATURES AND HOPEFULLY A BIT MORE SUNSHINE TO THE REGION. LOWS BY WEDNESDAY NIGHT AND THURSDAY NIGHT MAY DIP INTO THE 40S AGAIN FOR PORTIONS OF THE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1252 PM CDT FRI AUG 22 2014 A MOIST EASTERLY FLOW WILL CONTINUE THROUGHOUT THE TAF PERIOD. WE SHOULD START THE DAY LARGELY IN THE IFR/LIFR RANGE NEAR LAKE SUPERIOR...AND MVFR TO IFR AT INLAND LOCATIONS. SOME IMPROVEMENT IS POSSIBLE DURING THE AFTERNOON BUT WE SHOULD SEE CONDITIONS GO RIGHT BACK TO LOWER VALUES OVERNIGHT. WE ARE EXPECTED LARGE SCALE IFR/LIFR AND EVEN SOME VLIFR NEAR LAKE SUPERIOR OVERNIGHT AND LINGERING INTO SATURDAY. && .PRELIMINARY POINT TEMPS/POPS... DLH 68 60 70 61 / 30 10 20 60 INL 74 57 76 58 / 20 10 30 70 BRD 78 61 75 64 / 10 20 50 70 HYR 76 61 78 64 / 20 20 40 60 ASX 71 59 73 62 / 30 20 20 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR MNZ037. WI...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR WIZ001. LS...NONE. && $$ UPDATE...DAP SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...LE AVIATION...DAP
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1235 PM CDT Fri Aug 22 2014 .SHORT TERM: (Through Sunday) Issued at 312 AM CDT Fri Aug 22 2014 Well it finally feels like summer. Heat index values yesterday afternoon topped out around 105 degrees in the immediate St. Louis Metropolitan Area where the EXCESSIVE HEAT WARNING remains in effect until Sunday evening. Elsewhere, heat indices remained within the 100 to 104 degree range, including locations across northeast Missouri and west central Illinois. Will be adding the northeast Missouri and west central Illinois counties to the HEAT ADVISORY to account for heat index values reaching longevity criteria of 100 degree heat index for four or more days. I expect that the longevity of the heat wave (now likely extending into next week) will lead to future extensions in time as confidence increases. Have introduced some low chance POPs for thunderstorms this afternoon and evening across the northern half of the CWA. Hard to ignore mesoscale model guidance suggesting a secondary warm front developing across the northern CWA by this evening as low pressure deepens across the Central Plains. Both 00Z 4KM NCEP and NSSL WRF runs depict an active late afternoon and evening across the northern CWA - with the potential for an outflow to move south toward I-70. Again, for now, I have only increased POPs so that there is a mention in the forecast. Day shift will have to reevaluate as HRRR and RAP comes into range later this morning. CVKING .LONG TERM: (Monday through Thursday) Issued at 312 AM CDT Fri Aug 22 2014 Hot and dry conditions extend into next week ahead of a cold front that is now forecast to arrive on Wednesday. This front should bring a chance of rain and utlimately cooler temperatures by Thursday. CVKING && .AVIATION: (For the 18z TAFs through 18z Saturday Afternoon) Issued at 1223 PM CDT Fri Aug 22 2014 Main forecast issue is the probability for any showers and thunderstorms and the need for inclusion in any of the TAFS. An old thunderstorm boundary has sunk to around I-70 and this has caused some havoc in the wind direction although they are light. Indications the boundary will retreat northward and could result in scattered showers and thunderstorms this afternoon across northern Missouri into central IL which might impact KUIN. Confidence is below average and thus have just mentioned a VCTS for this afternoon. A higher probability of showers and thunderstorms will exist at KUIN during the overnight hours. Elsewhere can`t rule out isolated shower or thunderstorms with afternoon heating but the coverage and probability are too low to mention. Largely outside of any thunderstorms, VFR conditions will dominate with surface winds at or below 8 kts through the period. Specifics for KSTL: VFR conditions are expected to dominate much of the forecast period with surface winds at or below 8 kts. Will have to keep an eye out for any isolated showers or thunderstorms this afternoon, and then overnight tonight will need to monitor any showers and thunderstorms across northern MO sagging southeastward. Confidence and probabilities at this time are too low to mention in the TAF. Glass && .LSX WATCHES/WARNINGS/ADVISORIES: MO...HEAT ADVISORY until 7 PM CDT Sunday FOR Audrain MO-Boone MO- Callaway MO-Cole MO-Franklin MO-Gasconade MO-Jefferson MO- Knox MO-Lewis MO-Lincoln MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby MO-St. Charles MO-St. Francois MO-Ste. Genevieve MO-Warren MO. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR St. Louis City MO-St. Louis MO. IL...HEAT ADVISORY until 7 PM CDT Sunday FOR Adams IL-Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL- Macoupin IL-Marion IL-Monroe IL-Montgomery IL-Pike IL- Randolph IL-Washington IL. EXCESSIVE HEAT WARNING until 7 PM CDT Sunday FOR Madison IL-St. Clair IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
259 PM CDT FRI AUG 22 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 THE HIGHLIGHT OF THE SHORT TERM PERIOD WILL BE THE FACT WE ARE EXPECTING THUNDERSTORMS TODAY/TONIGHT. THERE STILL REMAINS SOME UNCERTAINTY FOR TIMING...LOCATION...AND OVERALL DEVELOPMENT. THE WARM FRONT TO OUR SOUTH...WHICH IS SITUATED OVER THE KANSAS/NEBRASKA BORDER...IS JUST MOSEYING ALONG TODAY AND HAS CAUSED SOME CONCERN FOR DEVELOPMENT. SHOWERS/STORMS SHOULD DEVELOP ALONG THIS BOUNDARY AS THE CAP BEGINS TO BREAK. SPC MESOSCALE ANALYSIS PAGE HAS US CAPPED UNTIL ABOUT 22-23Z. AT THIS TIME WE SHOULD SEE THE BEGINNING STAGES FOR INITIATION ALONG THE BOUNDARY TO OUR SOUTH. AMPLE INSTABILITY OF ABOUT 2000-3000 J/KG WILL BE IN PLACE...DUE TO A VERY MOIST BOUNDARY LAYER AND STEEP LAPSE RATES. MOST UNSTABLE CAPE COULD BE AS HIGH AS 4000 J/KG. BULK SHEAR 0-6 KM WILL BE AROUND 30 KNOTS...AND THIS IS NOT TOO IMPRESSIVE...HOWEVER...LOW LEVEL SHEAR WILL BE STRONG. EARLIER RUNS OF THE RAP INDICATED HELICITY VALUES NEAR 400 M2/S2 WOULD BE IN PLACE AROUND 23Z FOR WESTERN PORTIONS OF THE CWA. THESE VALUES WILL PUSH EASTWARD THROUGH THE AFTERNOON/EVENING. THESE LOW LEVEL HELICITY VALUES COUPLED WITH AMPLE INSTABILITY WILL POSE A THREAT FOR SOME ISOLATED TORNADOES...MAINLY FOR OUR NEBRASKA COUNTIES. WITH THAT BEING...WIND AND HAIL WILL BE THE MAIN THREATS TODAY/TONIGHT. THE BEST CHANCE FOR SEVERE WEATHER WILL BE ACROSS OUR NEBRASKA COUNTIES...BUT THE ENTIRE CWA DOES HAVE THE POTENTIAL FOR SEVERE WEATHER. I DO EXPECT THUNDERSTORM ACTIVITY TO KICK INTO GEAR AROUND 6 OR 7 PM...IF NOT SOONER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 VARIOUS RAIN CHANCES FOR THE WEEKEND AND IN TO THE FIRST PART OF THE WORK WEEK...ALONG WITH FLUXUATING TEMPERATURES ARE PRIMARY FORECAST CONCERNS. WILL KEEP THIS FAIRLY SHORT DUE TO POSSIBLE SEVERE WEATHER DEVELOPING LATER THIS AFTERNOON. STARTING OUT SATURDAY EVENING IN THE MID/UPPER LEVELS...THERE SHOULD BE A LARGE AMPLITUDE TROUGH OVER THE ROCKIES WITH A CLOSED LOW SITUATED OVER EAST CENTRAL MONTANA...AS THE CURRENT SYSTEM OVER THE PACIFIC NW DRIFTS EASTWARD. THIS WILL PUSH THE RIDGE A LITTLE EAST AS WELL WITH THE AXIS STRETCHING FROM LAKE SUPERIOR TO MISSISSIPPI. THE BETTER FORCING WITH THE LOW PRESSURE SHOULD BE TO THE WEST AND NORTH OF OUR REGION. AT THE SURFACE...EXPECT A FRONTAL BOUNDARY TO BE TO OUR NORTH ACROSS SDAK AT 00Z AND THEN THIS WILL PUSH INTO OUR AREA BY SUNDAY MORNING. HAS NOT TAKEN A WHOLE LOT TO SET OFF CONVECTION THE PAST WEEK AND WHILE THE SET UP FOR SATURDAY NIGHT IS NOT AS GOOD AS TONIGHT...WILL PROBABLY STILL NEED SOME LOW POPS GIVEN APPROACHING WEAK COLD FRONT AND ANTICIPATED LOW LEVEL JET. PREVIOUS SHIFT AFD NOTED SOME HEAT BURST POTENTIAL WITH ANY THUNDERSTORMS THAT DO DEVELOP AND THIS SCENARIO STILL IN PLACE. WEATHER SHOULD BE QUIET DURING THE DAYTIME ON SUNDAY BEHIND THE COLD FRONT AND POSSIBLE SUNDAY NIGHT ALTHOUGH BOTH THE NAM AND GFS ARE DEVELOPING SOME PRECIPITATION TO THE WEST AND MOVING ACROSS THE CWA SUNDAY NIGHT. GFS APPEARS TO OVERDEVELOP A VORTICITY MAX ALTHOUGH DIFFICULT TO TOTALLY DISCOUNT WITH CYCLONIC FLOW IN UPPER LEVELS. MONDAY NIGHT AND TUESDAY NIGHT STILL LOOK ACTIVE AS YET ANOTHER HIGH AMPLITUDE TROUGH IS SLATED TO MOVE ACROSS THE ROCKIES AND INTO THE PLAINS. AT THE SURFACE AN EAST/WEST STATIONARY FRONT WILL HANG OUT OVER THE AREA RESULTING IN THE CLASSIC NIGHTTIME RAIN EVENTS. BY WEDNESDAY THE EXTENDED MODELS IN DECENT AGREEMENT IN PUSHING THE TROUGH EAST THROUGH THE CWA WITH RIDING THEN MOVING IN TO QUIET THINGS DOWN FOR THE REMAINDER OF THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1240 PM CDT FRI AUG 22 2014 CONDITIONS AT BOTH TERMINAL SITES ARE EXPECTED TO REMAIN IN VFR THROUGHOUT MOST OF THE TAF PERIOD. THE ONLY CONCERN WILL BE THUNDERSTORM ACTIVITY LATER THIS AFTERNOON/EVENING. AT THIS TIME...CONDITIONS WILL LIKELY DETERIORATE. HOWEVER...CONFIDENCE IS NOT EXTREMELY HIGH AT THIS POINT FOR TIMING...LOCATION...AND OVERALL LIKELIHOOD OF DEVELOPMENT. AT THIS POINT...WE DO EXPECT SHOWERS/STORMS TO DEVELOP ALONG THE WARM FRONT WHICH IS JUST SOUTH OF BOTH TERMINAL SITES...NEAR THE NEBRASKA/KANSAS BORDER. THIS FRONT WILL MOSEY NORTH THROUGHOUT THE DAY AND ONCE THE CAP BREAKS SHOWERS SHOULD BEGIN. THE BEST CHANCE FOR THUNDERSTORM ACTIVITY IS INDICATED IN THE TAF TO BEGIN AROUND 01Z. THE TAF WILL BE AMENDED FOR ANY CHANGES ONCE INITIATION BECOMES CLEARER. CLOUD COVER WILL INCREASE THROUGHOUT THE DAY AND OVERNIGHT AS WELL...BUT CEILINGS SHOULD REMAIN VFR THROUGH THE VALID TAF PERIODS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...GUERRERO LONG TERM...EWALD AVIATION...GUERRERO
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1250 PM CDT FRI AUG 22 2014 .UPDATE... ISSUED AT 1236 PM CDT FRI AUG 22 2014 SCATTERED THUNDERSTORMS CONTINUE TO DEVELOP IN NORTHEAST KANSAS AND DRIFT INTO SOUTHEAST NEBRASKA THIS EARLY AFTERNOON IN WEAK MID LEVEL WARM ADVECTION REGIME. THESE WILL CONTINUE TO MEANDER THROUGH THE AREA BUT EXPECT COVERAGE TO GRADUALLY DIMINISH THROUGH THE AFTERNOON AS UPPER RIDGING NOSES SLIGHTLY NORTH AND WARMS MID LEVEL TEMPERATURES. FARTHER NORTH WHERE PLENTY OF SUNSHINE HAS BEEN SEEN...BROKEN CU FIELD HAS DEVELOPED JUST NORTHWEST OF INTERSTATE 80 NEAR STATIONARY FRONT DELINEATED BY LIGHT NORTHEAST WINDS IN NORTHEAST NEBRASKA AND SOUTHEAST WINDS TO THE SOUTH. LAST FEW RAP FORECASTS SUGGEST SOME CONVECTION COULD FIRE LATER THIS AFTERNOON CLOSE TO THIS BOUNDARY...LIKELY FROM THE OMAHA METRO AND WEST...IN AREA WHERE MLCAPES HAVE INCREASED TO NEAR 3500 J/KG. SHEAR IS WEAK HERE...BUT HIGH INSTABILITY COULD LEAD TO STRONG STORMS IF THINGS DO FIRE. OTHERWISE WE ARE STILL EXPECTING INCREASING CHANCES FOR STORMS AS THE EVENING PROGRESSES WITH APPROACH OF STRONG SHORTWAVE ENTERING THE HIGH PLAINS. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 341 AM CDT FRI AUG 22 2014 CONVECTIVE ACTIVITY HAS DEVELOPED OVER SWRN IA AND SERN NEB THIS MORNING ALONG A SFC TROF EXTENDING FROM NRN IA TO WRN KS. SIMILAR TO THE LAST SEVERAL NIGHTS...ENVIRONMENT IS QUITE UNSTABLE WITH MUCAPES AROUND 3000 J/KG WITH A STRONG LLVL MOISTURE FEED INTO THE PLAINS. EXPECT ACTIVITY WILL GRADUALLY DIMINISH OVER THE NEXT SEVERAL HOURS AND BE OUT OF THE CWA BY SUNRISE. MOST PRESSING ISSUE FOR THIS FCST PACKAGE IS POTENTIAL SVR TSTMS ALONG WITH HEFTY RAINFALL ANTICIPATED LATER TONIGHT. MODELS HAVE BEEN CONSISTENT LAST SEVERAL RUNS FOCUSING IN ON THE NRN CWA WITH RESPECT TO HIGH POTENTIAL FOR HEAVY NOCTURNAL PCPN LATER TONIGHT. AN OPEN GULF WITH PERSISTENT MOISTURE ADV THRU TODAY WILL ENSURE A MOISTURE RICH ENVIRONMENT WILL BE IN PLACE DURING THE OVERNIGHT HOURS. TODAY...MODELS PROG A POTENT LITTLE VORT MAX EJECTING OUT OF THE BASE OF A DEEP UPPER TROF SITUATED OVER THE WRN CONUS WITH DPVA INDUCING LEESIDE CYCLOGENESIS INVOF THE CNTRL HIGH PLAINS. MODELS AGREE SFC LOW WILL RAPIDLY LIFT TWD THE DAKOTAS THIS AFTN ALONG WITH ATTENDANT WARM FRONT PUSHING INTO THE CWA LATE THIS AFTN. COMBINATION OF STOUT INSTABILITY/EFF SHEAR AND ADEQUATE DEEP LYR SHEAR WITH PROVIDE A FAVORABLE ENVIRONMENT FOR LATE AFTN/EARLY EVENING SUPERCELL DEVELOPMENT. IN ADDITION...VERY HEAVY RAINFALL...MAINLY OVER THE NRN CWA...LOOKS VERY PROBABLE TONIGHT GIVEN COMBINATION OF WARM CLOUD DEPTH AROUND 4500 METERS/SYNOPTIC SCALE MAX OMEGA WILL BE IN PHASE WITH PWS GREATER THAN 2". BEST MOISTURE/FORCING THEN QUICKLY LIFTS NORTH OF THE CWA EARLY SAT MORNING. SAT NIGHT AND SUN...MODELS PROG A SOMEWHAT STRONG COLD FRONT APPROACHING THE CWA. NOT ALL THAT IMPRESSED WITH PCPN POTENTIAL SO WILL OPT FOR TOKEN 20S DURING THOSE PDS. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 341 AM CDT FRI AUG 22 2014 COMPARED TO 21/00Z RUN...LATEST ECM IS NOW TRYING TO COME BACK IN LINE WITH GFS/CMC SOLUTIONS SWEEPING A CANADIAN AIR MASS INTO THE NRN/CNTRL PLAINS LATER NEXT WEEK WITH PCPN CHANCES FOCUSED ON FRONTAL BNDRY PASSAGE. GOING POPS LOOK REASONABLE THUS NO MAJOR CHANGES PLANNED. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1236 PM CDT FRI AUG 22 2014 AREA OF CUMULUS CLOUDS HAD DEVELOPED AT TAF ISSUANCE TIME AND WILL AFFECT ALL TAF SITES THIS AFTERNOON. BROKEN CLOUDS WILL LIKELY REMAIN VFR...BUT SOME FL020 CIGS COULD OCCUR NEAR KOFK FOR A TIME EARLY IN THE AFTERNOON. THEN THE CHANCE FOR SCATTERED CONVECTION WILL INCREASE LATE THIS AFTERNOON...AND ESPECIALLY BY LATE EVENING...AS A STRONG SHORTWAVE LIFTS INTO THE PLAINS. STORMS COULD FIRE AT ANY TIME AFTER 22Z BUT LATEST TRENDS SUGGEST KOMA WILL BE MOST LIKELY SITE TO SEE AFTERNOON AND EARLY EVENING ACTIVITY. OTHERWISE EXPECT CHANCES AND AREAL COVERAGE TO INCREASE BY 05Z AT ALL SITES WITH KOFK THE MOST LIKELY TO SEE OVERNIGHT CONVECTION. ATTENDANT MVFR/IFR CONDITIONS WILL PREVAIL IN ANY STORMS. THUNDERSTORMS SHOULD BE MOVING NORTH OF ALL TAF SITES BY 14Z WITH VFR CONDITIONS AND SOUTHEAST WINDS NEAR 10KT PREVAILING. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ UPDATE...DERGAN SHORT TERM...DEE LONG TERM...DEE AVIATION...DERGAN
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
943 AM PDT FRI AUG 22 2014 .SYNOPSIS...A FEW LINGERING THUNDERSTORMS MAY OCCUR OVER NORTHWEST ARIZONA TODAY BEHIND A CIRCULATION MOVE TOWARD THE FOUR CORNERS REGION. A BROAD AREA OF LOW PRESSURE BRUSHING NORTHERN NEVADA WILL LEAD TO DRY SOUTHWEST FLOW WITH TEMPERATURES A LITTLE BELOW NORMAL ACROSS THE ENTIRE REGION THROUGH THE MIDDLE OF NEXT WEEK. && .UPDATE...THE LATEST OBSERVATIONS AND MODEL DATA SUPPORT THE GOING FORECAST AND NO IMMEDIATE CHANGES ARE NEEDED. THE 12Z LAS VEGAS SOUNDING SHOWED SIGNIFICANT WARMING AROUND 500 MB WHICH SHOULD KEEP A STRONG ENOUGH CAP TO INHIBIT CONVECTION OVER SOUTHERN NEVADA AND SOUTHEAST CALIFORNIA EVEN THOUGH MOISTURE WILL BE SLOW TO SCOUR OUT TODAY. THERE WILL STILL BE ENOUGH INSTABILITY FOR ISOLATED HEATING/TERRAIN DRIVEN THUNDERSTORMS OVER MOHAVE COUNTY. RECENT SATELLITE LOOPS SHOW SUBSTANTIAL MOISTURE OVER NORTHEAST NEVADA AHEAD OF A DIGGING TROUGH. THIS WILL BRUSH FAR NORTHERN LINCOLN COUNTY BY THIS EVENING WITH SHOWERS AND THUNDERSTORMS. THE TROUGH WILL INFLUENCE THE REST OF THE REGION WITH INCREASING SOUTHWEST BREEZES THIS AFTERNOON. && .PREV DISCUSSION... 255 AM PDT FRI AUG 22 2014 .SHORT TERM...THROUGH SUNDAY NIGHT UPPER LOW OVER SOUTHWEST ARIZONA NOW WILL LIFT NORTHEAST INTO THE FOUR CORNERS THIS AFTERNOON IN RESPONSE TO TROUGH DIGGING INTO THE PACIFIC NORTHWEST. REGIONAL RADAR SHOWS SOME LIGHT RAIN AROUND FLAGSTAFF WITH NOTHING IN OUR FORECAST AREA. HRRR SUGGESTS CONVECTION WILL GET ANOTHER EARLY START (BY 10 AM) OVER THE HIGHER TERRAIN OF SOUTHERN MOHAVE COUNTY WHERE SUFFICIENT MOISTURE/INSTABILITY REMAIN. IT WILL BE MUCH QUIETER ACROSS SOUTHEAST NEVADA AND EASTERN SAN BERNARDINO COUNTY AS SOME DRYING AND STABILIZATION OF THE AIR MASS OCCURS. FOR FAR NORTHERN LINCOLN COUNTY, MODELS CONTINUE TO INDICATE THE POTENTIAL OF SOME SHOWERS/THUNDERSTORMS IN PROXIMITY OF A STATIONARY FRONT OVER CENTRAL NEVADA. ON SATURDAY, THE ONLY MENTIONABLE POPS ARE ACROSS NORTHEAST LINCOLN AGAIN NEAR THE STATIONARY FRONT. ELSEWHERE, DRYING FROM THE WEST WILL OCCUR OVER THE WEEKEND. DUE TO THE APPROACHING TROUGH SOUTH/SOUTHWEST WINDS WILL INCREASE ACROSS THE WESTERN MOJAVE DESERT AND SOUTHERN GREAT BASIN THIS AFTERNOON BUT WILL REMAIN BELOW ADVISORY CRITERIA. HI RES MODELS ALSO SHOWING A WEAK DOWNSLOPE EVENT ALONG THE EASTERN SIERRA SLOPES SAY BETWEEN 3 PM AND 10 PM THIS EVENING. PLEASANT TEMPERATURES TO THE START EACH DAY WHILE DAYTIME HIGHS WILL CONTINUE TO RUN AROUND 3 TO 6 DEGREES BELOW NORMAL. .LONG TERM...MONDAY THROUGH FRIDAY NIGHT. AFTER FLYING SOLO LAST NIGHT, THE OPERATIONAL ECMWF RETURNED BACK TO A PROGNOSTICATION MORE SIMILAR TO WHAT IT HAD BEEN SHOWING ON PREVIOUS MODEL RUNS FOR EARLY NEXT WEEK. THIS PUTS IT IN MUCH BETTER AGREEMENT WITH THE OTHER OPERATIONAL MODELS AND THE VAST MAJORITY OF THE GFS ENSEMBLE MEMBERS WITH HOW IT HANDLES THE UPCOMING PATTERN. THE NEXT MID/UPPER LEVEL TROUGH IS FORECAST TO DROP SOUTHEAST ACROSS NEVADA MONDAY AFTERNOON INTO MONDAY NIGHT AND INTO UTAH BY TUESDAY. THE 00Z OPERATIONAL GFS WAS MORE SHALLOW WITH THE TROUGH THAN THE GEM AND ECMWF SO THE FORECAST SHOWS A BLEND BETWEEN THE TWO. UNLESS THIS TROUGH ENTRAINS ENOUGH SUBTROPICAL MOISTURE INTO IT, IT SHOULD PASS ON BY WITH LITTLE MORE THAN SOME HIGH CLOUDS AND PERHAPS SOME ENHANCED WINDS. TEMPS SHOULD BE HELD DOWN A FEW DEGREES BELOW NORMAL DUE TO THE LOWER HEIGHTS, BY WEDNESDAY INTO THURSDAY, A RIDGE ALOFT IS SHOWN TO BUILD IN FROM THE WEST WHICH SHOULD YIELD A WARMING TREND WITH HIGHS EDGING BACK TO OR A LITTLE ABOVE NORMAL. THIS RIDGE EITHER LOOKS TO GET STRETCHED OUT OR SHUNTED EAST BY FRIDAY AS ANOTHER MID/UPPER LEVEL TROUGH SLICES ACROSS NORCAL AND NORTHERN NEVADA. EITHER WAY, THERE DOES NOT LOOK TO BE ANY GREAT SIGN FOR MONSOON MOISTURE TO MAKE A RETURN BACK ON IN, SO THE FORECAST REMAINS DRY. TEMPS WERE A BLEND OF BIAS CORRECTED CONS MODELS WITH A LITTLE ECMWF AND MEX MOS MIXED ON IN. && .AVIATION...FOR MCCARRAN...A SOUTHEAST WIND COMPONENT CAN BE EXPECTED DURING THE LATE MORNING AND EARLY AFTERNOON BEFORE WINDS INCREASE FROM THE SOUTHWEST WITH GUSTS UP TO 25 KTS AFTER 22Z AND PERSIST INTO THE EVENING. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...A DRY SOUTHWEST FLOW WILL START TO SPREAD ACROSS MOST OF THE REGION TODAY WITH ANY THREAT OF THUNDERSTORMS CONFINED TO THE HIGHER TERRAIN OF MOHAVE COUNTY. SKIES WILL BE MOSTLY CLEAR ELSEWHERE. SOUTHWEST WINDS GUSTING AROUND 30 KNOTS THIS AFTERNOON IN THE WESTERN MOJAVE DESERT AND SOUTHERN GREAT BASIN. && .SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. && $$ UPDATE/AVIATION...ADAIR PREV DISCUSSION...PIERCE/STACHELSKI FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
513 PM EDT FRI AUG 22 2014 .SYNOPSIS... ROUNDS OF SHOWERS AND THUNDERSTORMS CONTINUE WITH OCCASIONAL DOWNPOURS...AS WEAK DISTURBANCES RIDE SE. HIGH PRESSURE WILL TRY TO NOSE IN FROM THE NORTHEAST EARLY NEXT WEEK AS UPPER RIDGE BUILDS. && .NEAR TERM /THROUGH SATURDAY/... 21Z UPDATE... NO MAJOR CHANGES...UPDATED PRECIPITATION TO BE A BIT MORE REPRESENTATIVE OF THE CURRENT SITUATION AND THE MOST CURRENT RUC AND HRRR MODEL RUNS. OLD BELOW... THE AREA WILL REMAIN IN THE WARM AND HUMID SECTOR WITH FRONTAL BOUNDARIES TO THE NORTH AND WEST. ALOFT...NORTHWEST FLOW AHEAD OF AN H5 RIDGE COULD BRING SOME IMPULSES OF ENERGY TO KEEP SHOWERS AND THUNDERSTORMS GOING THIS EVENING INTO EARLY SATURDAY MORNING. RADAR INDICATED AT 18Z...STORMS DEVELOPING ALONG INTERSTATE 64 FROM HTS TO CRW AND SOUTH...MOVING SOUTHEAST. SOME OF THE STRONGEST STORMS WILL BE CAPABLE TO PRODUCE ONE INCH PER HOUR. WITH NEARLY SATURATED TERRAIN...DECIDED TO KEEP THE FLASH FLOOD WATCH IN PLACE THROUGH TONIGHT. PREVIOUS TEMPERATURES LOOKS GOOD. DECREASED COUPLE OF DEGREES ON SATURDAYS HIGHS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... DRIER WX REGIME BEGINS TO SET IN AS UPPER RIDGE BUILDS INTO THE AREA. IT WILL BE WARM...BUT NOT HOT AS THE OPPRESSIVE HEAT REMAINS WELL W OF THE REGION. IT WILL STILL BE RATHER MUGGY THOUGH...TYPICAL DOG DAYS OF SUMMER. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... USED WPC THINKING WITH SOME TWEAKS. HIGH PRESSURE...AT THE SURFACE AND ALOFT...WILL DOMINATE THE REGION INTO WEDNESDAY NIGHT...BEFORE WEAKENING. THIS WILL ALLOW A COLD FRONT TO PUSH SOUTH INTO THE AREA ON THURSDAY...WITH THIS FEATURE EXPECTED DRIFT SOUTH THROUGH THE REMAINDER OF THE PERIOD. WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... 21Z UPDATE... UPDATED CEILINGS AND PRECIPITATION TO BE REPRESENTATIVE OF THE CURRENT CONDITIONS. NO MAJOR CHANGES MADE. OLD BELOW... RADAR IMAGES SHOW STORMS DEVELOPING SOUTH AND ALONG A LINE FROM CRW TO BKW AT 18Z. THESE STORMS WILL AFFECT BKW DIRECTLY WITH MVFR/IFR CONDITIONS UNDER STORMS. PCPN ACTIVITY IS EXPECTED TO DECREASE AFTER SUNSET. HOWEVER...ADDITIONAL CONVECTION COULD DEVELOP OVERNIGHT INTO EARLY SATURDAY. WITH VERY HIGH HUMIDITY IN THE LOW TO MID LEVELS...EVIDENT IN SFC DEWPOINTS IN THE LOWER 70S...AND PWATS EXCEEDING 2 INCHES...LOW LEVEL CLOUDS WILL LIKELY DEVELOP OVERNIGHT FOR PERIODS OF IFR CONDITIONS ESPECIALLY OVER THE HIGHER TERRAIN. LOCALIZED DOWNPOURS CAN PRODUCE BRIEF IFR VSBY AND CEILINGS AT TIMES. CEILINGS BECOMING MAINLY 2 TO 3 THSD FT BKN WITH LAYERS AND VSBY 5 TO 6 MILES IN HAZE AFTER ABOUT 22Z. YET...ADDITIONAL CLUSTERS OF SHOWERS AND STORMS LIKELY...INTO THE EVENING HOURS...AGAIN WITH IFR VSBY AND CEILINGS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: DURATION AND TIMING ROUNDS OF CONVECTION WILL VARY. AT LEAST SOME AREAS OF PCPN MAY EVEN LINGER LONGER FRIDAY NIGHT...BUT NOT MENTIONED IN TAFS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 EDT 1HRLY 16 17 18 19 20 21 22 23 00 01 02 03 CRW CONSISTENCY H H M M M M M M H H H M HTS CONSISTENCY M M M M H H H H H H H H BKW CONSISTENCY M M M M M M M M M H H H EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY M M M M M M M M M H H H CKB CONSISTENCY H H M M M M M M M H H H AFTER 18Z SATURDAY... IFR CONDITIONS POSSIBLE IN LOW STRATUS IN LINGERING LOW LEVEL MOISTURE SATURDAY AFTERNOON. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLASH FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR WVZ005>011- 013>020-024>040-046-047. OH...FLASH FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR OHZ066-067-075- 076-083>087. KY...FLASH FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR KYZ101>103-105. VA...FLASH FLOOD WATCH UNTIL 1 AM EDT SATURDAY FOR VAZ003-004. && $$ SYNOPSIS...ARJ/30 NEAR TERM...ARJ/LS SHORT TERM...30 LONG TERM...JSH AVIATION...ARJ/LS
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A WEAK AREA OF LOW PRESSURE SPINNING OVER WESTERN WISCONSIN EARLY THIS AFTERNOON. ALTHOUGH UPPER DIVERGENCE IN THE RIGHT REAR QUAD OF A JET STREAK HAS SHIFTED OFF TO THE EAST...CONVERGENCE NORTH OF A SURFACE WARM FRONT HAS GENERATED SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM OVER NORTH-CENTRAL WISCONSIN. ALSO OBSERVING RATHER BUBBLY LOOKING CU ALONG A COLD FRONTAL TYPE FEATURE MOVING INTO CENTRAL WISCONSIN THOUGH CONVERGENCE LOOKS QUITE WEAK...AND THE ONLY RETURNS ARE LOCATED OVER NORTHEAST IOWA. THE ATMOSPHERE IS GROWING UNSTABLE AHEAD OF THIS TROUGH/COOL FRONT WITH ML CAPES GROWING TO GREATER THAN 1000 J/KG...AND CIN FALLING RAPIDLY. THE NAM CREATES CONVECTION OVER CENTRAL WISCONSIN LATER THIS AFTERNOON...SO THIS IS SOMETHING TO KEEP AN EYE ON. INCLUDED A ISOLATED THUNDERSTORM MENTION FOR THE REST OF THE AFTERNOON OVER CENTRAL WISCONSIN. MEANWHILE...A LARGE UPPER TROUGH OVER THE PAC NW WILL SHIFT EAST CAUSING A WARM FRONT TO RE-ORGANIZE OVER THE PLAINS ON SATURDAY. PRECIP CHANCES AND FOG POTENTIAL REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...MODELS ARE HAVING A TOUGH TIME LATCHING ON TO THAT LOW LEVEL CIRCULATION OVER WESTERN WISCONSIN. THE NAM AND TO A LESSER EXTEND THE GEM APPEAR TO HAVE A BETTER HANDLE ON THIS FEATURE THAN OTHER GUIDANCE. BUT CONFIDENCE WILL REMAIN LOW IN ANY CASE. BOTH THE NAM AND GEM SHOW THIS SURFACE LOW WEAKENING LATER THIS AFTERNOON OR THIS EVENING AND MORPHING INTO A SURFACE TROUGH OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. THIS WILL KEEP AN ISOLATED TO SCATTERED THREAT OF SHOWERS AND STORMS INTO THE EVENING...AND POSSIBLY INTO THE OVERNIGHT HOURS TOO. THIS TROUGH WILL ALSO PROMOTE FOG DEVELOPMENT IN THESE AREAS TONIGHT AND THINK ANOTHER DENSE FOG ADVISORY WILL BE POSSIBLE FOR THE EARLY MORNING COMMUTE TOMORROW. LIGHT EASTERLY WINDS MAY ALSO ADVECT AREAS OF MARINE FOG INLAND INTO THE LAKESHORE COUNTIES TONIGHT. WARM AND MUGGY WITH LOWS IN THE 60S. SATURDAY...LOW PRESSURE WILL EMERGE INTO THE CENTRAL PLAINS AHEAD OF A DEEP PAC NW TROUGH. THE LOW LEVEL FLOW WILL REORGANIZE AND A WARM FRONT WILL LIFT INTO SOUTHWEST WISCONSIN IN THE AFTERNOON. THIS LOOKS TO BE A LITTLE SLOWER THAN YESTERDAYS RUNS AND WILL BACK OFF PRECIP CHANCES DURING THE MORNING. CHANCES IMPROVE DURING THE AFTERNOON OVER CENTRAL AND NORTH-CENTRAL WISCONSIN BUT AM SKEPTICAL SINCE THE FRONT WILL STILL BE WELL SOUTHWEST OF THE REGION AND MID-LEVEL RIDGING SHARPENS ALOFT. SO WILL MATCH WITH OTHER OFFICES BUT BRING UP CONCERN TO THE NEXT SHIFT. ONCE THE MORNING FOG AND LOW CLOUDS BURN OFF...CONTINUED WARM AND HUMID WITH HIGHS IN THE UPPER 70S TO LOWER 80S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 SATURDAY NIGHT INTO SUNDAY...THE UPPER RIDGE GETS NUDGED TO THE EAST A TAD WHILE A BROAD UPPER TROUGH APPROACHES FROM THE NORTHERN AND CENTRAL PLAINS. A DEEPENING LOW PRESSURE SYSTEM WILL LIFT NORTHWARD OVER THE NORTHERN PLAINS...AND LIFT A WARM FRONT NORTH OVER THE AREA. SOME PROGS GENERATE SOME CONVECTION WITH THIS FRONT SAT NIGHT INTO SUNDAY MORNING. CONVECTION MAY STRUGGLE TO DEVELOP DUE TO PROXIMITY TO THE UPPER RIDGE SO KEPT POPS ON THE LOW SIDE AND DECREASED THE DURATION OF THE CONVECTION MENTION. ISOLATED CONVECTION MAY LINGER SUNDAY MORNING ACROSS NORTHERN WISCONSIN...BUT BY NOON THE H850 BOUNDARY IS PROGGED TO BE WELL NORTH OF THE AREA. ANY PRECIPITATION CHANCES DURING THIS PERIOD WILL TEND TO BE FOCUSED TOWARD NORTHWEST WISCONSIN TOWARD THE BEST HEIGHT FALLS. SUNDAY NIGHT INTO MONDAY...NEXT CHANCE OF CONVECTION ALONG A TROUGH OR WEAKENING COLD FRONT. MOST MODEL RUNS DIMINISH THE PCPN AS IT WORKS INTO EASTERN WISCONSIN CLOSER TO THE UPPER RIDGE WHICH REMAINS OVER THE EASTERN GREAT LAKES AND MUCH OF THE EAST THIRD OF THE COUNTRY. THE BRUNT OF THE CONVECTION WILL LIKELY TRACK OVER NORTHWEST WISCONSIN AND ESPECIALLY OVER MINNESOTA NEAR THE SURFACE AND 850 LOW LIFTING NORTHEAST. MONDAY NIGHT...BROAD RRQ REGION OF THE UPPER JET FOCUSES THE CONVECTION OVER THE CENTRAL PLAINS WHILE WHILE WEAK HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE FROPA. THE GFS WAS THE ODD MODEL OUT WITH STALLING THE FRONT OVER THE AREA AND CONTINUING CONVECTION MONDAY NIGHT. MOST OF THE MODELS FOR THE REST OF NEXT WEEK...THE UPPER PATTERN SHIFTS FROM A SOUTHWEST FLOW ALOFT TO A NEARLY ZONAL FLOW LATE IN THE WEEK...BUT SOME AGREEMENT WITH MOST MODELS WITH RESPECT TO A MORE ROBUST SHORT WAVE WITH RRQ UPPER JET REGION PASSING THROUGH TOWARD MID WEEK. COULD SEE ANOTHER ROUND OF A SOAKING RAIN WITH THE SURFACE FRONT AND H850 FRONT INTERACTING WITH THE UPPER JET. TEMPERATURES WILL BE ABOVE NORMAL THROUGH TUESDAY...AND WELL ABOVE NORMAL IN A STICKY AIR MASS SUNDAY ESPECIALLY IF THE CLOUDS CLEAR OUT. TEMPERATURES COOLING BACK TO NEAR NORMAL LATER NEXT WEEK. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1206 PM CDT FRI AUG 22 2014 A WARM AND VERY MOIST LATE SUMMER AIRMASS WILL REMAIN IN PLACE THROUGH THE TAF PERIOD. WEAK LOW LEVEL CONVERGENCE WILL PROMOTE ISOLATED TO SCATTERED SHOWER DEVELOPMENT THIS AFTERNOON OVER NORTH-CENTRAL AND POSSIBLY FAR NORTHEAST WISCONSIN. THE ISOLATED SHOWERS COULD LINGER INTO THE EVENING OVER FAR N-C WISCONSIN. OTHERWISE...EXPECT CIGS AND VSBYS TO LOWER QUICKLY BY MID TO LATE EVENING ACROSS THE REGION...WITH AREAS OF DENSE FOG DEVELOPING AGAIN LATE TONIGHT. CIGS AND VSBYS TO IMPROVE VERY SLOWLY TOMORROW MORNING. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
329 PM MDT FRI AUG 22 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 300 PM MDT FRI AUG 22 2014 PRETTY ACTIVE THE NEXT 24 TO 48 HOURS. TEMPERATURES AND POPS ARE THE FORECAST CHALLENGES FOR THE SHORT TERM. CURRENTLY...WATER VAPOR IMAGERY SHOWING A PRETTY PRONOUNCED WAVE IN THE MONSOONAL FLOW MOVING NORTH THIS AFTERNOON OUT OF NEW MEXICO INTO WEST CENTRAL COLORADO. MOSAIC RADAR SHOWING WIDESPREAD SHOWERS OVER CENTRAL COLORADO EARLY THIS AFTERNOON WITH A GENERAL NORTH NORTHEAST MOVEMENT ON THE CELLS. INFRARED RADAR SHOWING COOLING CLOUD TOPS WITH THIS WAVE AND WE ARE SEEING AN UPTICK IN LIGHTNING STRIKES ACROSS WESTERN COLORADO. UPPER LOW OVER IDAHO FAIRLY DYNAMIC AS WELL WITH NUMEROUS LIGHTNING STRIKES DEVELOPING. LATEST SPC MESOANALYSIS SHOWING A SLOW EROSION OF CIN OVER EXTREME SOUTHEAST WYOMING INTO THE KIMBALL AREA...WITH CAPE VALUES AROUND 1000 J/KG ABOVE. LOOKING AT CLOUD COVER OVERHEAD...IT IS PRETTY DENSE AND WE HAVE BEEN HARD PRESSED TO GET MUCH WARMING SO FAR TODAY. 1 PM TEMPERATURES HERE AT THE OFFICE AT 69 DEGREES WITH LOW TO MID 70S OUT IN THE PANHANDLE. FOR THIS EVENING...SHORTWAVE BEGINS TO MOVE INTO SOUTHEAST WYOMING SHORTLY AFTER 00Z WITH GUIDANCE INDICATING FAIRLY WIDESPREAD CONVECTION DEVELOPING AS THIS HAPPENS. THE 16Z HRRR FORECAST HAS CONVECTION DEVELOPING HERE AT CHEYENNE AROUND THE 22Z TIME FRAME...THEN EXPANDING ACROSS SOUTHERN WYOMING INTO THE PANHANDLE AFTER WARDS. BY 01Z...MOST LOCATIONS EAST OF THE LARAMIE RANGE SHOULD BE SEEING MEASURABLE RAINFALL WITH SCATTERED SHOWERS OUT WEST. NAM SOUNDINGS FOR THE PANHANDLE SHOWING PRETTY STRONG SHEAR OUT IN THE PANHANDLE THIS EVENING. LOOKING AT EASTERLY WINDS NEAR THE SURFACE OF 15 TO 20KTS WITH SOUTHWEST 40-45KTS AT 6KM. EVENING SHIFT WILL DEFINITELY NEED TO BE WATCHING FOR SEVERE THUNDERSTORMS. 0-3KM HELICITY FOR SIDNEY AT 386M2/S2 AT 00Z. GIVEN THE THICK CLOUD COVER THOUGH...CHANCES ARE DIMMING THAT WE WILL SEE SEVERE THUNDERSTORMS. SOMETHING ELSE FOR THIS AFTN/EVE...PRECIPITABLE WATER VALUES REALLY HIGH FOR THE PANHANDLE. SIDNEY SOUNDING SHOWING 1.42 INCHES...EXTENDING UP TO CHADRON AT 1.40 INCHES. FORECAST QPF REALLY HIGH FOR THE PANHANDLE AND EXTREME EASTERN WYOMING TONIGHT. GOOD NEWS IS FORECAST STORM MOTIONS ARE FROM THE SOUTHWEST AT 14-16KTS...SO THESE STORMS SHOULD BE MOVING FAIRLY FAST. WILL NEED TO WATCH THOUGH FOR TRAINING THUNDERSTORMS AND THERE COULD BE SOME FLASH FLOODING FOR SOME AREAS THIS EVENING. GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT WITH THE UPSTREAM LOW ON THIS 12Z RUN. BOTH SHOWING THE CLOSED LOW MOVING PRETTY SLOW THROUGH NORTHERN WYOMING THROUGH THE DAY SATURDAY. MOST OF SATURDAY WILL SEE SHOWERS LASTING MOST OF THE DAY. WENT SIGNIFICANTLY HIGHER ON POPS OVER GUIDANCE. DO BELIEVE THE MID SHIFT WILL PROBABLY WANT TO GO HIGHER. FINALLY SATURDAY EVENING...THE UPPER LOW MOVES OFF INTO SOUTH DAKOTA WITH RAIN ENDING FROM WEST TO EAST. GOING TO BE PRETTY COOL WITH 700MB TEMPERATURES DOWN TO +6C SATURDAY NIGHT. SHOULD SEE WIDESPREAD 40S OUT WEST FOR LOWS...WITH LOW 50S EAST. CLOUD COVER COULD PROVIDE SLIGHTLY WARMER TEMPERATURES...WE WILL HAVE TO SEE AS THE EVENT GETS CLOSER. DID GO UNDER GUIDANCE FOR SUNDAY LOWS...ESPECIALLY OUT WEST WHERE CLOUD COVER WOULD BE LESS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 335 PM MDT FRI AUG 22 2014 MEDIUM RANGE MODELS IN GOOD AGREEMENT THROUGH EARLY TUESDAY...BUT THEN SOLUTIONS BEGIN TO DIVERGE THROUGH WEDNESDAY...WITH POOR CONSISTENCY BETWEEN THE 12Z AND 00Z MODEL RUNS APPARENT INTO LATE NEXT WEEK. EARLY IN THE WEEK...MOIST SOUTHWEST FLOW AHEAD OF A POSITIVELY TILTED UPPER LEVEL TROUGH WILL MOVE ACROSS ACROSS THE IDAHO AND INTO WESTERN WYOMING. A WEAK BOUNDARY WILL DEVELOP AND DRIFT WESTWARD ALONG THE LARAMIE RANGE...WHICH WILL RESULT IN UPSLOPE FLOW AND ENHANCE LIFT ACROSS THE HIGH PLAINS. KEPT POP BETWEEN 35 TO 60 PERCENT ACROSS THE AREA WITH A GOOD CHANCE OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS. ALL MODELS SHOW THIS ACTIVITY LINGERING THROUGH MONDAY NIGHT AS WELL AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY...WHICH WILL EVENTUALLY TRANSITION INTO A COLD FRONT. KEPT POP AROUND 50 PERCENT MONDAY NIGHT. WILL HAVE TO WATCH FOR STRONG TO SEVERE THUNDERSTORMS MONDAY EVENING WITH CAPE VALUES AROUND 1500 TO 2000 J/KG...HIGH PW/S...AND INSTABILITY. ECMWF STILL TRENDING SLOWER WITH THE UPPER LEVEL TROUGH COMPARED TO THE GFS. THE GEM HAS TRENDED TOWARDS THE ECMWF WHILE THE GFS PUSHES THE TROUGH THROUGH THE FORECAST AREA AS EARLY AS TUESDAY AFTERNOON. THE ECMWF AND GEM SHOW THE TROUGH AXIS MOVING ACROSS THE AREA LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE GEM AND ECMWF SOLUTIONS THEN DIVERGE WITH THE ECMWF SHOWING THE SYSTEM ATTEMPTING TO CLOSE OFF ON WEDNESDAY. EITHER WAY...EXPECT TUESDAY AND TUESDAY EVENING TO REMAIN UNSETTLED WITH COOLER THAN NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD RAINFALL. HIGHS MAY STRUGGLE TO REACH THE MID TO UPPER 60S ON TUESDAY AS 700MB TEMPERATURES LOWER BELOW 5C AFTER THE FRONT MOVES THROUGH THE AREA. LOW CONFIDENCE ON THE WEDNESDAY FORECAST DUE TO SIGNIFICANT MODEL DIFFERENCES. KEPT A SLIGHT CHANCE OF SHOWERS AND TSTORMS FOR NOW DUE TO TIMING DIFFERENCES...EVEN THOUGH THE ECMWF SOLUTION IS UNLIKELY TO OCCUR. MUCH DRIER AIR MOVES INTO THE REGION THURSDAY AND FRIDAY BASED ON CURRENT MODEL RUNS AS THE RIDGE AXIS REDEVELOPS WEST OF THE ROCKY MOUNTAINS AND DRIFTS EASTWARD. BASED ON 12Z MODELS...WARMER TEMPERATURES AND DRY CONDITIONS ARE EXPECTED NEXT WEEK. HOWEVER...THERE IS A LARGE CONTRAST BETWEEN THESE SOLUTIONS AND THE PREVIOUS 00Z SOLUTIONS FROM LAST NIGHT WHICH SHOW A PACIFIC SYSTEM MOVES INTO THE REGION WITH ANOTHER STRONG COLD FRONT ENTERING WYOMING BY LATE FRIDAY. KEPT TEMPERATURES NEAR NORMAL FOR NOW WITH POP BELOW 10 PERCENT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY MORNING) ISSUED AT 1145 AM MDT FRI AUG 22 2014 A BAND OF RAIN SHOWERS AND ISOLATED THUNDER WILL CONTINUE OVER THE SOUTHERN NEBRASKA PANHANDLE OVER THE NEXT HOUR OR TWO BEFORE DISSIPATING BY EARLY THIS AFTERNOON. EXPECT A BRIEF BREAK...WITH MAINLY VFR CONDITIONS THIS AFTERNOON. THE ONLY EXCEPTION WILL BE KCDR WHICH WILL MAINTAIN A LOW STRATUS DECK. ALL MODELS INDICATE AN AREA OF HEAVY SHOWERS AND STRONG THUNDERSTORMS DEVELOPING OVER THE HIGH PLAINS SOMETIME LATE THIS AFTERNOON AS A STRONG UPPER LEVEL DISTURBANCE LIFT NORTHWARD OUT OF NEW MEXICO...AND WILL CONTINUE TO MOVE NORTHWARD ACROSS THE AREA TONIGHT. FAIRLY CONFIDENT OF MVFR OR IFR CONDITIONS IN THESE HEAVY SHOWERS WITH THE POTENTIAL FOR FOG AND LOW STRATUS RESULTING IN AN EXTENDED PERIOD OF BORDER-LINE IFR CONDITIONS INTO SATURDAY MORNING ACROSS THE HIGH PLAINS. KRWL AND KLAR SHOULD REMAIN VFR TONIGHT WITH MOST OF THE ACTIVITY FURTHER TO THE EAST...BUT CAN NOT RULE OUT SOME SHOWERS AND TSTORMS OVER THOSE AREAS AS WELL. && .FIRE WEATHER... ISSUED AT 300 PM MDT FRI AUG 22 2014 MINIMAL FIRE WEATHER CONCERNS ACROSS THE AREA THROUGH THE NEXT FEW DAYS. UPPER LOW PRESSURE OVER IDAHO THIS AFTERNOON WILL BRING INCREASING MONSOONAL MOISTURE AND FAIRLY WIDESPREAD RAINFALL TO MUCH OF THE AREA TONIGHT INTO SATURDAY. BEST CHANCES FOR WETTING RAINS WILL BE ALONG AND EAST OF THE LARAMIE RANGE AS WELL AS THE SNOWY AND SIERRA MADRE RANGES. THE UPPER LOW WILL GRADUALLY MOVE INTO WESTERN SOUTH DAKOTA EARLY SUNDAY MORNING WITH RAINS ENDING FROM WEST TO EAST. COOLER TEMPERATURES BEHIND THE LOW WILL KEEP AFTERNOON HUMIDITIES FAIRLY HIGH WITH EXCELLENT OVERNIGHT RECOVERIES THROUGH THE MIDDLE OF NEXT WEEK. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...TJT FIRE WEATHER...CLAYCOMB