Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 300526 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 126 AM EDT SAT APR 30 2016 .SYNOPSIS... DRIER AIR LINGERS INTO TONIGHT. WARM FRONTAL SHOWERS INCREASE SATURDAY. MORE INSTABILITY SUNDAY WITH COLD FRONT SINKING SOUTHEAST SUNDAY NIGHT. DRIER MONDAY. WAVE PASSES TO THE SOUTHEAST TUESDAY. && .NEAR TERM /THROUGH TODAY/... 650 PM UPDATE...INCREASED SKY COVER ACROSS THE CWA THIS EVENING AS OVERCAST CIRRUS HAS TAKEN HOLD. THIS MAY HAVE AN EFFECT ON FOG DEVELOPMENT TONIGHT ACROSS THE NORTH. OTHERWISE...PREVIOUS FORECAST OK. PREVIOUS DISCUSSION FOLLOWS... AFTER YESTERDAYS SHOWERS/STORMS THAT FORMED DURING THE MID AFTERNOON AND LINGERED INTO THE EVENING...PLUS THE LOCALIZED HAILERS...WE WELCOME THE DRIER AIR TODAY. THE COLD AIR ADVECTION HELPED TO HOLD THE LOW CLOUDS THE LONGEST FRIDAY IN EASTERN OHIO...MOSTLY NORTH OF THE ROUTE 50 CORRIDOR. BEFORE WE LOOK OUT OUR WEST AND SOUTHWEST WINDOW...STILL NEED TO MONITOR THE MID LEVEL DISTURBANCE DROPPING SOUTHEAST THROUGH PENNSYLVANIA THIS EVENING. NO REASON TO REMOVE OUR SLIGHT CHANCE OF A RAIN SHOWER IN OUR EXTREME NORTHEAST FOR EARLY THIS EVENING. WITH CLEARING EXPECTED...DEW POINTS SHOULD LOWER SOME FOR THE REST OF THIS AFTERNOON IN THE NORTH. THINKING THE CIRRUS AND APPROACHING MID DECK WILL STAY THINNER IN THESE NORTHERN COUNTIES LATE TONIGHT. AS A RESULT...WITH THE WETTER GROUND...AND STILL A LOCAL MAXIMUM IN DEW POINT....WILL INSERT SOME FOG AFTER 04Z IN EASTERN OHIO FROM THE HOCKING VALLEY ON NORTH AND ALSO FOR THE ROUTE 50 CORRIDOR IN WEST VIRGINIA...PLUS THE TYGART VALLEY AROUND ELKINS. FURTHER SOUTH...IN THE DRIER AIR...NO FOG TONIGHT WITH THE HIGH CLOUDS THICKENING INTO MID DECK. WILL HAVE RAIN SHOWERS SPREADING N DURING THE 12Z TO 18Z TIME FRAME. MAIN CHANCE WAS TO TRY TO LOWER POPS FROM CRW ON SOUTH TOWARD WILLIAMSON AND THE SOUTHERN COAL FIELDS AS THE PSEUDO WARM FRONTAL LIFT SHIFTS NORTH. WITH SOUTHEAST FLOW THOUGH...FIGURING LOWER CLOUDS ALONG EASTERN SLOPES...WILL NOT REDUCE POPS LATE IN THE DAY FOR THOSE EASTERN SLOPES INCLUDING POCAHONTAS COUNTY. WILL KEEP CHANCE OF THUNDER AOB 14 PCT. COULD NOT RULE OUT AN EMBEDDED T IN OHIO ASSOCIATED WITH THE BEST LIFT...BUT THINK HIGHER CHANCES ARE SATURDAY NIGHT AND SUNDAY. && .SHORT TERM /TONIGHT THROUGH MONDAY/... A RATHER MESSY FORECAST STILL FOR SATURDAY NIGHT THROUGH SUNDAY. LOOKS LIKE WE MAY HAVE A DRY PERIOD SATURDAY NIGHT ACROSS THE WEST...BUT STILL HANGING ONTO CHANCE POPS. HAVE LIKELY POPS ACROSS THE MOUNTAINS. ENTIRE CWA SHOULD GET SOME RAIN ON SUNDAY...BUT TIMING IS RATHER DIFFICULT. NAM SHOWS SOME BREAKS DURING THE AFTERNOON...WITH THE MAIN SLUG IN THE MORNING...WHILE GFS AND ECMWF HAVE LESS DEFINITION. THIS ALL MAKES IT DIFFICULT TO HIGHLIGHT WHEN THESE DRIER PERIODS MAY BE ON SUNDAY...SO GENERALLY KEPT HIGH POPS THROUGHOUT THE DAY...GRADUALLY TAPERING OFF SUNDAY NIGHT INTO MONDAY. DESPITE THE SHOWERS AND CLOUDS AROUND IN THE MORNING...THE NAM STILL INDICATED SOME DECENT INSTABILITY SUNDAY. IN ADDITION...NAM BULK SHEAR HAS INCREASED IN RECENT RUNS -- NOW GENERALLY 40-50KTS SUNDAY AFTERNOON. THINK THE MORNING ACTIVITY SHOULD LIMIT INSTABILITY SOME...BUT STILL CANNOT RULE OUT SOME STRONGER THUNDERSTORMS WITH GUSTY WINDS AND POSSIBLY HAIL. ALONG PWATS LOOK TO BE THE HIGHEST SATURDAY NIGHT ACROSS THE WESTERN HALF OF THE CWA...MAXING OUT JUST OVER 1.5 IN. GENERALLY HAVE ABOUT 1 INCH OF QPF SATURDAY NIGHT THROUGH SUNDAY NIGHT. BUT ANY AREAS THAT RECEIVE REPETITIVE DOWNPOURS COULD START EXPERIENCING MINOR WATER ISSUES. WILL KEEP MENTION IN HWO FOR NOW. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 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 /06Z SATURDAY THROUGH WEDNESDAY/...
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OVERNIGHT...VFR CONDITIONS WILL PREVAIL...EXCEPT AT EKN...PKB...AND CKB THAT COULD SEE SOME MVFR/IFR FOG DURING THE PREDAWN HOURS. SATELLITE IMAGES SHOW HIGH CLOUDS CREEPING IN FROM THE SOUTH AND WEST...SHOULD GENERALLY PREVENT DENSE FOG DEVELOPMENT OVERNIGHT. A WARM FRONT LIFTS NORTH ON SATURDAY...WITH SCATTERED SHOWERS AND ISOLATED STORMS DURING THE EARLY AFTERNOON. WIDESPREAD MVFR CONDITIONS DEVELOPING AFTER 15-18Z...PARTICULARLY ACROSS THE EASTERN SLOPES OF THE HIGHER TERRAIN AND AT SITES SUCH AS KBKW AS A SOUTHEASTERLY FLOW TAKES HOLD. WV LOWLANDS MAY BE SLOWER TO DEVELOP MVFR CONDITIONS IN THE SOUTHEASTERLY DOWNSLOPING FLOW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: CLOUD COVER COULD PREVENT FOG DEVELOPMENT TONIGHT. TIMING...COVERAGE AND DURATION OF ANY FOG OVERNIGHT TONIGHT COULD VARY. TIMING AND DEVELOPMENT OF MVFR CONDITIONS ON SATURDAY COULD VARY FROM FORECAST. 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 SAT 04/30/16 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H M L L L L L L L H H PKB CONSISTENCY H H M L L L L L L L M H CKB CONSISTENCY H H M L L L L L L L H H AFTER 06Z SUNDAY... IFR POSSIBLE AGAIN SATURDAY NIGHT INTO SUNDAY NIGHT WITH ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO MONDAY MORNING.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/TRM/MZ NEAR TERM...KTB/ARJ/SL SHORT TERM...MZ LONG TERM...TRM AVIATION...ARJ

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