Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231448 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1048 AM EDT WED JUL 23 2014 .SYNOPSIS... COLD FRONT SINKS SOUTH TODAY...INCREASING SHOWERS AND STORMS. FRONT PASSES TONIGHT...WITH WAVE ALONG FRONT LATE TONIGHT AND EARLY THURSDAY. DRIER AIR ARRIVES ON THURSDAY. BRIEF HIGH PRESSURE FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM UPDATE... ADJUSTMENTS MADE TO POPS AND SKY TO REFLECT CURRENT CONDITIONS AND TRENDS. INCREASED POPS/SKY JUST A BIT MAINLY SOUTHEAST OF THE I79 CORRIDOR AS A COUPLE OF THIN PREFRONTAL BANDS OF SHOWERS AND EMBEDDED THUNDER MOVE SLOWLY EAST/SOUTHEAST. LOWERED POPS THROUGH THE MORNING HOURS OVER THE NORTHWEST HALF OF THE AREA WITH CURRENT VIS SHOWING A GOOD AMOUNT OF SUNSHINE OVER THAT AREA. STILL EXPECT A QUICK RAMP-UP OF CLOUDS AND PRECIP BY THE EARLY/MID AFTERNOON HOURS. PREVIOUS DISCUSSION... CERTAINLY WAS A WARM AND MUGGY OVERNIGHT AND EARLY MORNING...WITH DEW POINTS ON EITHER SIDE OF 70 DEGREES. HAVE LOW CONFIDENCE ON EXACTLY HOW THE AREAS OF CONVECTION WILL EVOLVE TODAY INTO TONIGHT. YET...TRIED TO KEEP THE HIGHER POPS...IN THE LIKELY RANGE...OUT AHEAD OF THE FRONT FOR TODAY...THEN LINGERED THOSE HIGHER POPS A BIT LONGER IN OUR SOUTHERN COUNTIES LATE TONIGHT...AS THE MID LEVEL 500 MB TROF AXIS ACTS ON THE BAROCLINIC ZONE. EVEN AS DAWN APPROACHES...COULD NOT RULE OUT SHOWERS FORMING THIS MORNING...PATCHES OF CLOUDS HAVE BEEN FORMING PAST FEW HOURS. PROBABLY RELATED TO THE INCREASE LOW LEVEL FLOW...COULD NOT LOCATE/FIND ANY DISTURBANCES. SO WE STILL KEPT THE FOG AT A MINIMUM FOR DAWN. MOSTLY IN THE DEEPER MOUNTAIN VALLEYS. SOME THUNDERSTORMS COULD FORM DURING THE DAYTIME INSTABILITY FURTHER SOUTH...AWAY FROM THE APPROACHING FRONT...OVER SOUTHERN COUNTIES. EQUILIBRIUM LEVELS TRY TO REACH 35 TO 40 THSD...ESPECIALLY ACROSS SOUTHERN LOWLANDS THIS AFTERNOON. MID LEVEL WINDS RATHER WEAK. YET...COULD NOT RULE OUT A PULSE STORM REACHING SEVERE LIMITS...BUT OVERALL THE THREAT FOR A LOT OF DAMAGING WIND GUSTS OR LARGE STILL APPEARS TO BE RATHER LOW. OF COURSE THE USUAL LIGHTNING AND DOWNPOURS STILL DESERVES RESPECT. HAVE THE FRONT ITSELF REACHING INTO THE MID OHIO VALLEY NEAR MARIETTA AND PARKERSBURG AROUND 00Z THIS EVENING...THEN REACHING OUT SOUTHERN MOUNTAINS AROUND BKW ABOUT 09Z THURSDAY. YET...WINDS AT MOST LEVELS BEGIN TO VEER BEFORE THE SURFACE FRONT PASSES. HAVE THUNDER CHANCES DECREASING N/S OVERNIGHT...EVEN THOUGH POPS REMAIN RELATIVELY HIGH IN THE SOUTH DURING THE LATE NIGHT HOURS. LOWERED MAXIMUM TEMPERATURES...ESPECIALLY IN THE NORTH WHERE CLOUDS AND HIGHER POPS EXPECTED SOONER. HAVE THE NORTH WIND DRIVING SOUTH IN SOUTHEAST OHIO TONIGHT...WITH SOME CLEARING THERE LATE TONIGHT...AND LOWERED MINIMUM TEMPERATURES A BIT ESPECIALLY FROM HOCKING VALLEY NORTH. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... WHILE COLD FRONT WILL BE THROUGH FORECAST AREA TO START THE SHORT TERM...POST FRONTAL PRECIP WILL STILL BE LINGERING AS UPPER LEVEL TROUGH APPROACHES. WILL BE DRYING OUT FOR FRIDAY AS SURFACE HIGH PRESSURE CROSSES. ALL MODELS SHOW A FAIRLY WEAK 500MB SHORTWAVE TROUGH SLIDING ACROSS IN NW FLOW FRIDAY NIGHT INTO SATURDAY. INCREASED POPS FRIDAY NIGHT ANTICIPATING DECAYING CONVECTIVE COMPLEX APPROACHING FROM THE WEST ON A STRONG WAA AT 850MB. ALSO INCREASED POPS ON SATURDAY WITH THE ACTUAL UPPER LEVEL RIPPLE. BEHIND THE COLD FRONT...AND WITH LINGERING CLOUDS...EXPECT HIGH TEMPS ON THURSDAY TO STAY BELOW 80. ADDED A COUPLE DEGREES TO THAT FOR FRIDAY WITH MORE SUNSHINE...AND THEN ANOTHER COUPLE DEGREES SATURDAY AS THE WINDS TURN MORE SOUTHERLY. EXPECTING A COOLER NIGHT THURSDAY NIGHT WITH LOTS OF READINGS IN THE 50S. CLOUDS SHOULD KEEP FRIDAY NIGHT JUST A TOUCH WARMER. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... USED HPC GUIDANCE FOR MOST OF THE WEATHER ELEMENTS WITH A FEW MINOR TWEAKS THROUGH THE PERIOD. ALTHOUGH NORTHWEST FLOW AT H5 WEAKENS SOME 5H...A SHORTWAVE IS EXPECTED BY MODELS TO SLIDE ACROSS OUR AREA LATER SATURDAY INTO SUNDAY. THIS FEATURE COULD BRING CHANCES FOR RAIN SHOWERS OR STORMS BY THE SECOND HALF OF THE WEEKEND. A LARGE OCCLUDING SYSTEM MEANDERS SOUTH THROUGH MONDAY...AS CUT- OFF LOW DEVELOPS OVER THE GREAT LAKES. BOTH ECMWF AND GFS IN FAIRLY GOOD AGREEMENT IN PLAYING OUT THIS SCENARIO LATE IN THE PERIOD FOR A GENERAL UPSWING IN PRECIPITATION CHANCES BY EARLY MONDAY. WEAK AND FRESH NORTHERLY FLOW PREVAILS BEHIND THE FRONT TUESDAY WITH PLEASANT TEMPERATURES EXPECTED. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM MODELS CONTINUE TO FORM SPOTTY SHOWERS AND A FEW THUNDERSTORMS THIS MORNING. CELLS DID FORM PKB TO CKB VCNTY AROUND 10Z. MAY BE RELATED TO THE INCREASING LOW LEVEL FLOW...AFTER 2 DAYS OF DEAD FLOW. OUTFLOW FROMM OLDER CONVECTION SINKING SOUTH THROUGH OHIO. INCREASED POPS SOONER IN SOUTHEAST OHIO THIS MORNING. STILL TIMING THE FRONT TO REACH THE MID OHIO VALLEY AROUND PKB ABOUT 00Z...THEN EKN TO CRW AROUND 04Z...AND THE SOUTHERN MOUNTAINS AROUND BKW BEFORE DAWN...AROUND 08Z. TIMING THE VARIOUS ROUNDS OF CONVECTION TODAY INTO TONIGHT...HAS CONFIDENCE LEVEL LOWERED TO LOW. THERE COULD EVEN BE SOME SEPARATE CONVECTION FORMING OVER THE SOUTHERN COUNTIES...AWAY FROM THE FRONT...DUE TO THE DAYTIME INSTABILITY. HAVE THE LIKELY POPS...MOST COVERAGE...AHEAD OF THE FRONT ITSELF. THOSE LIKELY POPS REACHING INTO SOUTHEAST OHIO AFTER 15Z...AND INTO CENTRAL WEST VIRGINIA TOWARD 18Z...THEN HTS TO CRW CORRIDOR 20/21Z...AND BKW AFTER 00Z. AGAIN THAT IS FOR THE MOST COVERAGE. CEILINGS 2 TO 3 THSD FT AND VSBY AOB 3 MILES IN ANY PREFRONTAL CONVECTION. IN THE WAKE OF THE FRONT...HAVE SHOWERS LINGERING ACROSS SOUTHERN AND MOUNTAIN COUNTIES AT 06Z THURSDAY...WITH WAVE ACTION ALONG THE FRONT. SO HOLDING LIKELY POPS THROUGH THE NIGHT...BUT TRANSITIONING TO MOSTLY SHOWERS...RATHER THAN THUNDERSTORMS. CEILINGS LOWERING 1 TO 2 THSD FT AND VSBY AROUND 3 MILES IN POST FRONTAL SHOWERS. CEILINGS OVER HIGH MOUNTAINS LIKELY TO DROP BELOW 1 THSD FT AND VSBY BLO 3 MILES. MEANWHILE...DRIER AIR MOVING SOUTH INTO SOUTHEAST OHIO AND TOWARD PKB. SO HAVE CEILINGS STARTING TO IMPROVE/LIFT FROM THE NORTH TOWARD 06Z THURSDAY...THEN CONTINUING TO IMPROVE IN THE MID OHIO VALLEY 06Z TO 12Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: TIMING THE VARIOUS CLUSTERS OF SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT WILL LIKELY VARY. 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 14 15 16 17 18 19 20 21 22 23 00 01 EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 CRW CONSISTENCY H H H H H H H H M M M M HTS CONSISTENCY H H H H H H H M M M M M BKW CONSISTENCY H H H H M H H H H H H M EKN CONSISTENCY M H H H H H M H M M M H PKB CONSISTENCY H H H H H M M H H H H H CKB CONSISTENCY H H H H H H M M M M M H AFTER 12Z THURSDAY... IFR CONDITIONS IN LINGERING WAVE ALONG THE FRONT OVER SOUTHERN WEST VIRGINIA AND SOUTHWEST VIRGINIA INTO THURSDAY MORNING. IFR POSSIBLE SATURDAY AND SUNDAY IN ROUNDS OF CONVECTION. && .EQUIPMENT... PKB ASOS IS NOT SENDING A COMPLETE OBSERVATION. NWS TECHS ARE WORKING ON THE PROBLEM. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB/50 SHORT TERM...MZ LONG TERM...ARJ AVIATION...JS EQUIPMENT...KTB

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