Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 302336 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 736 PM EDT SAT APR 30 2016 .SYNOPSIS... WARM FRONT CROSSING THE AREA THIS AFTERNOON. UNSTABLE SUNDAY WITH COLD FRONT SINKING SOUTHEAST SUNDAY NIGHT. DRIER MONDAY. WAVE CROSSES TUESDAY. LARGE UPPER TROUGH BRINGS COOL AND UNSETTLED WEATHER TOWARD END OF THE WEEK. && .NEAR TERM /THROUGH SUNDAY/...
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715 PM UPDATE...TWEAKED POPS BASED ON CURRENT TRENDS. OVERALL...NO SIGNIFICANT WATER ISSUES...AS PRECIPITATION AMOUNTS HAVE REMAINED GENERALLY LIGHT...GENERALLY LESS THAN HALF AN INCH. SOME CONVECTION NOTED ON RADAR TO OUR SOUTH AND WEST...THESE MAY BRING SOME HEAVIER DOWNPOURS. WILL ALLOW THE FFA TO CONTINUE THROUGH THE SHIFT...AS ADDITIONAL RAIN EXPECTED THIS EVENING AND INTO OVERNIGHT HOURS. SATELLITE ESTIMATES PW VALUES STEADILY INCREASING WITH THE AID OF A LLJ...ALREADY ESTIMATED AT 1.4 INCHES TO OUR WEST IN EASTERN KY. OTHERWISE...A RATHER DREARY NIGHT ON TAP...WITH OCCASIONAL RAIN SHOWERS...AND LOWERING CEILINGS. EXPECTING LITTLE CHANGE IN THE OVERNIGHT TEMPERATURE WITH THE THICK CLOUD COVER IN PLACE. STILL LOOKING AT A DECENT BET FOR A FEW SEVERE STORMS TOMORROW...AS WELL AS A CONTINUED FLASH FLOOD THREAT...AS COLD FRONT...AND UPPER SHORTWAVE TROUGH APPROACH THE REGION...WITH MODELS INDICATING ABOUT 1500 J/KG CAPE...AND 0-6KM BULK SHEAR 50+KTS. ENTIRE CWA IN A MARGINAL RISK FOR TOMORROW. MAIN THREATS...HAIL AND WIND. PREVIOUS DISCUSSION FOLLOWS... WARM FRONT LIFTING THROUGH THE AREA THIS AFTERNOON. THUS FAR NOT A WHOLE LOT OF QPE OVER OUR CWA AS A COUPLE THOUSAND FEET OF DRY AIR BELOW 5KFT IS EATING MOST OF THE RAIN BEFORE IT HITS THE GROUND. MAIN CONCERN IS OVERNIGHT WHEN MOISTURE ADVECTION ERODES THE DRY LAYER AND PWATS INCREASE TO 1.5 IN AS INSTABILITY BEGINS TO BUILD AND FFG REMAINS FAIRLY LOW OVER THE ENTIRE AREA FROM RECENT RAINFALL. DO NOT EXPECT TONIGHT TO BE THE BIG SHOW THOUGH...MORE OF A PRIMER FOR ANYTHING THAT OCCURS ON SUNDAY AFTERNOON/EVENING. HOWEVER...THERE MAY BE AN ISOLATED EVENT TONIGHT THAT MAY WARRANT WATER HEADLINES. THE AREA WILL GET A LITTLE BREAK ON SUNDAY MORNING BEFORE THE NEXT SYSTEM ARRIVES SUNDAY AFTERNOON. THIS SYSTEM STREAMS A JUICY 1.7 IN PWAT RIVER INTO THE REGION WITH MUCH MORE WIDESPREAD INSTABILITY...THUS WILL LIKELY NEED ANOTHER FLASH FLOOD WATCH FOR SUNDAY AFTERNOON AND EVENING.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... COLD FRONT MOVES THROUGH SUNDAY NIGHT...WITH POPS TAPERING OFF ACROSS THE MOUNTAINS MONDAY MORNING. THE BULK OF MONDAY WILL BE DRY...ALTHOUGH MOISTURE ALREADY BACK ON THE INCREASE FROM THE SOUTH IN ADVANCE OF NEXT SYSTEM. THAT ARRIVES MONDAY NIGHT INTO TUESDAY...AS MODELS CONTINUE TO DRIFT FARTHER NORTH WITH A WAVE COMING OUT OF THE SOUTHERN STATES. HAVE INCREASED POPS MONDAY NIGHT WITH THIS. BOTH GFS AND NAM ALSO BRING UPPER TROUGH THROUGH ON TUESDAY...SO INCREASED TO HIGH CHANCE POPS WITH THIS. ECMWF ALSO SHOWS THE UPPER TROUGH...ALTHOUGH IS NOT AS ROBUST AS GFS/NAM. SO WHILE THE ECMWF DOES STILL HAVE PRECIPITATION AROUND...BUT KEEPS IT MORE TIED TO SURFACE WAVE FARTHER EAST. LEFT MENTION OF THUNDER OUT TUESDAY WITH COOLER TEMPERATURES AND ABUNDANT CLOUDS. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... MODELS CONCUR ON A LARGE UPPER LEVEL LOW DOMINATING THE WEATHER PATTERN THIS PERIOD...WITH EARLIER DIFFERENCES IN LATITUDE AND DEPTH GREATLY DIMINISHED. THE INSTIGATING UPPER LEVEL TROUGH DIGS INTO THE AREA TUESDAY NIGHT AND WEDNESDAY. THIS DRIVES A SURFACE COLD FRONT THROUGH THE AREA WEDNESDAY...WITH THE CHANCE FOR SHOWERS PUSHING FROM NORTHWEST TO SOUTHEAST. STILL HAVE NO MENTION OF THUNDER WITH THIS FRONT AS THE AIR AHEAD OF IT SHOULD BE ON THE DRY SIDE...BUT IT IS NOT OUT OF THE QUESTION A CHANCE MAY EVENTUALLY NEED ADDED. ONCE THE FRONT IS THROUGH...THE UPPER LEVEL TROUGH CLOSES OFF WEDNESDAY NIGHT INTO THURSDAY SOMEWHERE OVER THE APPALACHIANS. IT THEN MEANDERS SLOWLY FROM PA TO THE DELMARVA / JERSEY SHORE THROUGH SATURDAY. THIS WILL BRING ABOUT UNSEASONABLY COOL WEATHER WITH LOTS OF CLOUDS...AND A GOOD CHANCE FOR SHOWERS. THE CHANCE FOR SHOWERS WILL BE GREATEST OVER THE HIGHER TERRAIN BENEATH THE LOW UPPER LEVEL HEIGHTS AND TEMPERATURES...AND ALONG THE WESTERN SLOPES ON NORTHWEST UPSLOPE FLOW. TEMPERATURES ALOFT ARE PROGGED TO BE LOW ENOUGH FOR SNOW TO AT LEAST MIX IN ACROSS THE VERY HIGHEST TERRAIN WHEN SURFACE TEMPERATURES THERE WOULD BE AT THEIR LOWEST...EARLY FRIDAY AND SATURDAY MORNINGS. STILL HAVE THE CHANCE FOR THUNDER OUT OF THE FORECAST...BUT SOME AFTERNOON CHARGE SEPARATION IS NOT OUT OF THE QUESTION BENEATH THE LOW UPPER LEVEL HEIGHTS AND TEMPERATURES IN EARLY MAY. THE LARGE SYSTEM STARTS TO PULL OUT SATURDAY NIGHT...PROMOTING OVERNIGHT DRYING. TEMPERATURES THURSDAY AND FRIDAY WERE LOWERED ON THE MIDNIGHT SHIFT IN LIGHT OF INCREASING MODEL AGREEMENT ON THE LARGE UPPER LEVEL LOW...AND NO FURTHER CHANGES WERE NEEDED FOR THE MOST PART. TEMPERATURES EARLIER ON WERE CLOSE TO GUIDANCE BLENDS AND ACCEPTED...AND A GUIDANCE BLEND WAS USED FOR SATURDAY AND SATURDAY NIGHT. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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BOUNDARY LIFTING NORTH ACROSS THE AREA THIS EVENING. LOOKING AT A BRIEF BREAK IN MUCH OF THE SHRA THIS EVENING...BEFORE ANOTHER ROUND APPROACHES FROM THE WEST 04-06Z. EXPECTING CIGS TO GRADUALLY LOWER TO WIDESPREAD MVFR AND LOCAL IFR GENERALLY AFTER 04Z. COULD EVEN BE ISOLD LIFR CIGS AT TIMES TOO...PARTICULARLY IN SHRA. IN ADDITION...ISOLD TSRA...GENERALLY ACROSS SOUTHWEST VA...SOUTHERN WEST VIRGINIA AND NORTHEAST KY THROUGH 06Z. OTHERWISE...SOME GENERAL IMPROVEMENT TO LOW VFR AFTER 12-14Z...OUT AHEAD OF AN APPROACHING COLD FRONT...WHICH WILL GENERATE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ACROSS THE AREA. EXPECT HEAVY DOWNPOURS...LARGE HAIL...AND STRONG WIND GUSTS IN VICINITY OF STORMS...ALONG WITH BRIEF MVFR AND IFR CONDITIONS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND INTENSITY OF SHOWERS AND STORMS COULD VARY...AND PRODUCE IFR CONDITIONS ALONG THEIR PATH. TIMING OF ANY IMPROVEMENT TO VFR ON SUNDAY 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. UTC 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 EDT 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H M M H H H H H H M M M BKW CONSISTENCY M M L L L L L L M M M M EKN CONSISTENCY M M M M M M M M M M M M PKB CONSISTENCY H H M M M H H H M M M M CKB CONSISTENCY H H M M M M M M M M M H AFTER 00Z MONDAY... IFR POSSIBLE THROUGH LATE 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...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR WVZ005>011- 013>020-024>040-046-047. OH...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR OHZ066-067-075- 076-083>087. KY...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR KYZ101>103-105. VA...NONE. && $$ SYNOPSIS...TRM/JW/MZ/MPK NEAR TERM...JW/SL SHORT TERM...MZ LONG TERM...TRM AVIATION...SL

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