Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 301425 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1025 AM EDT SAT APR 30 2016 .SYNOPSIS... WARM FRONT TODAY. UNSTABLE SUNDAY WITH COLD FRONT SINKING SOUTHEAST SUNDAY NIGHT. DRIER MONDAY. WAVE PASSES TO THE SOUTHEAST TUESDAY. LARGE UPPER TROUGH BRINGS COOL AND UNSETTLED WEATHER TOWARDS END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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10 AM UPDATE...INCREASED POPS/QPF THROUGH TONIGHT. LARGE SCALE RAIN WAS CONCERNING ENOUGH TO ISSUE FLASH FLOOD WATCH ESPECIALLY SINCE THERE SHOULD BE EMBEDDED CONVECTIVE CELLS AS EVIDENCED BY REGIONAL RADAR RETURNS AND MODEL CONVECTIVE FEEDBACK SIGNATURES. PREVIOUS DISCUSSION FOLLOWS...A WARM FRONT WILL GRADUALLY LIFT NORTH...BRINGING SCATTERED TO NUMEROUS SHOWER WITH EMBEDDED THUNDERSTORMS THIS AFTERNOON AND EVENING. HIGH RESOLUTION MODELS ARE IN AGREEMENT WITH THE ONSET OF PCPN OVER SOUTHERN WV AND NORTHEAST KY BY 18Z SATURDAY. PRECIPITABLE WATER ABOUT 1.25 INCHES...DECENT DEEP LAYER SHEAR ABOUT 45 KNOTS...BUT LOW SFC CAPE WILL COMBINE TO PRODUCE MAINLY SHOWERS THROUGH TONIGHT. MODELS INDICATE H850 TEMPERATURES WILL BE AROUND 12C THROUGH THE PERIOD. TEMPERATURES WILL BE MILD DUE TO CLOUD COVER AND COOLING SHOWERS...GENERALLY IN THE LOWER 70S LOWLANDS...RANGING INTO THE LOWER 60S HIGHER ELEVATIONS. WENT CLOSER TO THE NATIONAL BLEND OF MODELS FOR TEMPERATURES THROUGH THE PERIOD.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SHOULD HAVE A BRIEF LULL IN THE SHOWER ACTIVITY SUNDAY ACROSS THE CENTRAL TO WESTERN FORECAST AREA AFTER WARM FRONTAL PASSAGE AND BEFORE COLD FRONT APPROACHES IN THE AFTERNOON. GUIDANCE INDICATES MODEST INSTABILITY LATER SUNDAY WITH CAPE VALUES IN THE 1000 - 1500 J/KG RANGE AND HEIGHT FALLS AS SHORTWAVE APPROACHES SUNDAY EVENING WILL STEEPEN LAPSE RATES CLOSE TO 7C/KM. ALSO OF NOTE WILL BE 0-6KM SHEAR VALUES OF 40 - 50KTS...WHICH SUPPORTS ORGANIZED UPDRAFTS. BIG QUESTION WILL BE HOW MUCH SUN POKES THROUGH DURING THE DAY TO FURTHER ADD TO THE INSTABILITY...AS LOW CLOUDS MAY LINGER ACROSS MUCH OF THE AREA DUE TO THE EARLY MORNING ACTIVITY. EVEN SO WE SHOULD STILL HAVE ENOUGH FORCING WITH THE COLD FRONT TO KICK OFF SOME STRONGER THUNDERSTORMS...WITH SOME POSSIBLY CONTAINING GUSTY WINDS AND HAIL. SPC HAS EXTENDED A MARGINAL RISK AREA FOR SEVERE STORMS ACROSS THE REGION. ANY STORMS THAT DO DEVELOP WILL HAVE TO BE CAREFULLY MONITORED FOR FLASH FLOODING...ESPECIALLY AFTER THE HEAVY RAIN FROM SATURDAY NIGHT INTO SUNDAY MORNING THAT WILL PRIME THE AREA. HIGH PRESSURE AND RIDGING SHOULD GIVE US A BRIEF REPRIEVE FROM STORMY CONDITIONS ON MONDAY...HOWEVER THE PROGRESSIVE PATTERN WILL MAKE ANY BREAK IN THE ACTION SHORT LIVED AS NEXT SHORT WAVE COULD ARRIVE AS EARLY AS LATE MONDAY NIGHT INTO TUESDAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 08Z MORNING UPDATE...ENSEMBLE AND OPERATIONAL MODELS ARE COMING INTO BETTER AGREEMENT FOR THE END OF NEXT WEEK...WITH LARGE UPPER LOW/TROUGH BECOMING ENTRENCHED OVER THE REGION. THIS PATTERN WILL LIKELY BRING COOL AND UNSETTLED CONDITIONS TO THE REGION. HAVE DECIDED TO GO AHEAD AND UPDATE THE LONG TERM FOR TEMPERATURES THU- SAT. IN THIS PATTERN...TEMPERATURES ARE LIKELY TO BE UNSEASONABLY COOL AND SOME WINTRY PRECIPITATION COULD BE POSSIBLE ACROSS THE HIGHER TERRAIN IN THE EASTERN FORECAST AREA. PREVIOUS DISCUSSION... MODELS STILL DIFFER ON WAVE CROSSING THE MIDDLE ATLANTIC STATES TUESDAY INTO WEDNESDAY...BUT THERE IS INCREASING CONSENSUS ITS MOISTURE AFFECTS AT LEAST SOUTHEASTERN PORTIONS OF THE FORECAST AREA. MODELS ALSO REMAIN A BIT OUT OF SYNC WITH A COUPLE OF NORTHERN STREAM SYSTEMS THAT CROSS MID TO LATE WEEK. THE GFS BRINGS COLD FRONTS ACROSS LATE WEDNESDAY AND THEN FRIDAY NIGHT...WHILE THE ECMWF TIMING IS EARLY THURSDAY ON THE FIRST COLD FRONT...AND THEN IT JUST CLOSES OFF A LARGE UPPER LOW THAT THEN SLOWLY LUMBERS THROUGH THE AREA AT LEAST THE END OF THE PERIOD. THE GFS IS FARTHER NORTH AND DEEPER WITH THE UPPER LOW...HENCE THE MORE DEFINED SECOND SURFACE FRONT. AS FOR THE UPPER LOWS...THIS IS A CLASSIC CASE OF DEEPER...BY ABOUT 350M...AND FARTHER NORTH VERSUS WEAKER AND FARTHER SOUTH. THE CURRENT FORECAST BRINGS FRONTS AND THE ASSOCIATED CHANCE FOR SHOWERS ACROSS WEDNESDAY AND FRIDAY NIGHTS...SIMILAR TO THE WPC DEPICTION. KEPT LOWS CLOSE TO PREVIOUS FORECAST AND A GUIDANCE BLEND. BLENDED IN GFS-BASED GUIDANCE FOR HIGHS...A LITTLE LOWER THAN PREVIOUS FORECAST FOR THE MOST PART. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
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A WARM FRONT LIFTS NORTH TODAY...WITH SCATTERED SHOWERS AND ISOLATED STORMS. WIDESPREAD MVFR CONDITIONS CAN BE EXPECTED AFTER 15-18Z...UNDER PERIODS OF RAIN OR THUNDER. PCPN SHOULD REACH HTS AND CRW AROUND 16Z TODAY...AND SPREAD NORTH THROUGH THIS EVENING. PERIODS OF IFR ARE POSSIBLE IN SHOWERS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND INTENSITY OF SHOWERS AND STORMS COULD VARY...AND PRODUCE IFR CONDITIONS OR WORST ALONG THEIR PATH. 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 12 13 14 15 16 17 18 19 20 21 22 23 EDT 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 CRW CONSISTENCY H H H H M M M M M M M M HTS CONSISTENCY H H H M M M M M M M M M BKW CONSISTENCY H H H M M M M M M M M M EKN CONSISTENCY H H H H H H M M M M M M PKB CONSISTENCY H M H H H H M M M M M M CKB CONSISTENCY H H H H H H H M M M M M AFTER 12Z SUNDAY... IFR POSSIBLE AGAIN THROUGH SUNDAY NIGHT WITH ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO MONDAY MORNING.
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&& .RLX WATCHES/WARNINGS/ADVISORIES...
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WV...FLASH FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH SUNDAY MORNING FOR WVZ005>011-013>020-024>040-046-047. OH...FLASH FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH SUNDAY MORNING FOR OHZ066-067-075-076-083>087. KY...FLASH FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH SUNDAY MORNING FOR KYZ101>103-105. VA...NONE.
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&& $$ SYNOPSIS...ARJ/JW/MPK NEAR TERM...ARJ/JW SHORT TERM...MPK LONG TERM...TRM/MPK AVIATION...JW

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