Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 010723 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 323 AM EDT SUN MAY 1 2016 .SYNOPSIS... WARM FRONT LIFTS NORTH TODAY. UNSTABLE...WITH COLD FRONT SINKING SOUTHEAST TONIGHT. DRIER MONDAY. WAVE CROSSES TUESDAY. LARGE UPPER TROUGH BRINGS COOL AND UNSETTLED WEATHER TOWARD END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... LIKELY TO CATEGORICAL POPS ARE FORECAST FOR TODAY AS A WARM FRONT LIFTS NORTH. ALTHOUGH RAINFALL ACCUMULATIONS HAVE BEEN LIGHT...IN THE ORDER OF 0.25 IN THREE HOURS...THIS WILL PRIME THE SOILS TO BECOME NEARLY SATURATED BY MID DAY. MODELS SUGGEST SFC CAPE VALUES AROUND 2000 J/KG...ABOUT 50 KNOTS OF DEEP LAYERED SHEAR AND PRECIPITABLE WATER AROUND 1.25 INCHES. THESE PARAMETERS ARE NEEDED FOR THUNDERSTORM DEVELOPMENT. AFTERNOON SHOWERS AND STORMS WILL BE CAPABLE TO PRODUCE MODERATE TO HEAVY RAIN...POSING A THREAT FOR FLASH FLOODING. UNSTABLE CONDITIONS TOGETHER WITH FREEZING LEVELS OF ABOUT 11500 FEET CAN PRODUCE HAIL STONES SOME SEVERE. WENT WITH THE SUPER BLEND GUIDANCE FOR TEMPERATURES THROUGH THE PERIOD. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... 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 /WEDNESDAY 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 /07Z SUNDAY THROUGH THURSDAY/... NUMEROUS LIGHT RAIN SHOWERS WILL CONTINUE TO MOVE NORTHEAST ACROSS THE AREA OVERNIGHT. ALTHOUGH THERE ARE SOME SIGNS OF DECREASING INTENSITY...ADDITIONAL SHOWERS UPSTREAM WILL REACH THE AREA DURING THE OVERNIGHT HOURS. EXPECT CEILINGS TO GRADUALLY LOWER FOR WIDESPREAD MVFR AND LOCAL IFR GENERALLY UNDER THE HEAVIER SHOWER OR STORM. BRIEF ISOLATED IFR CEILINGS WILL BE POSSIBLE AT MOST SITES. WHILE IFR VISIBILITIES WILL BE BRIEF. SPC HAS THE ENTIRE AREA UNDER A SLIGHT RISK FOR SEVERE WEATHER. EXPECT STORMS TO DEVELOP THIS AFTERNOON WHEN SFC BASED CAPE PEAKS AT AROUND 2000 J/KG...DEEP LAYERED SHEAR AROUND 50 KNOTS AND PRECIPITABLE WATER ABOUT 1.37 INCHES. EXPECT HEAVY DOWNPOURS...LARGE HAIL...AND STRONG WIND GUSTS IN VICINITY OF STORMS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z 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. DATE SUN 05/01/16 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY M M M M M H H H H H H H HTS CONSISTENCY L L L L L M M M M M H H BKW CONSISTENCY M M M M M M M M H H H H EKN CONSISTENCY M M M M M M M M H H H H PKB CONSISTENCY M M M M M H H H H H H H CKB CONSISTENCY M M M M M H H H H H H H AFTER 06Z MONDAY... IFR POSSIBLE THROUGH LATE SUNDAY NIGHT WITH ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO MONDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR WVZ005>011- 013>020-024>040-046-047. OH...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR OHZ066-067- 075-076-083>087. KY...FLASH FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR KYZ101>103- 105. VA...NONE. && $$ SYNOPSIS...ARJ/MPK NEAR TERM...ARJ SHORT TERM...MPK LONG TERM...TRM AVIATION...ARJ

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