Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 190604 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 204 AM EDT TUE AUG 19 2014 .SYNOPSIS... A VERY WARM...HUMID AND ACTIVE WEATHER PATTERN CONTINUES...WITH FREQUENT DISTURBANCE MOVING THROUGH NORTHWEST FLOW ALOFT ALMOST DAILY. && .NEAR TERM /THROUGH TODAY/... 200 AM UPDATE... IT APPEARS THE NEXT S/W TROUGH APPROACHING THE MIDDLE OHIO VALLEY FROM THE NW WILL HOLD OFF ALMOST UNTIL TUE EVENING. OTHERWISE DICEY STRATUS AND FOG FCST OVERNIGHT IS GENERALLY ON TRACK IN THE LARGER SCHEME OF THINGS. PREV DISCN... THE STRONG MID LEVEL VORT MAX...THAT HAD US CONCERNED THE PAST 2 DAYS...HAS MOVED ACROSS THE CWA AND EAST IN VIRGINIA BY 23Z. EVEN THE LINGERING SHOWERS IN THE CENTRAL MOUNTAINS WERE STARTING TO SINK SOUTH AT 23Z...RATHER THAN NEARLY STATIONARY. WILL CONTINUE TO DRY OUT POPS FIRST IN THE MID OHIO VALLEY...THEN MOVE SLOWLY SOUTH. AS A RESULT..LEAVE CHANCE POPS THE LONGEST ACROSS SOUTHERN COUNTIES. OTHERWISE...DESPITE LINGERING CLOUDS...FOG SHOULD BE THE MAIN STORY OVERNIGHT INTO EARLY MORNING. FIGURING ON SOME STRATUS CLOUDS COULD LINGER AFTER DAWN IN SOUTHERN WEST VIRGINIA...BEFORE LIFTING. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... CONTINUED ACTIVE IN THE SHORT TERM PERIOD...WITH PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS EACH DAY. GENERALLY SPEAKING...THE HIGHEST CHANCES FOR PRECIP OCCUR TUE EVENING AND THEN AGAIN THURSDAY...WITH A LESSER CHANCE OF PRECIP WED. OVERALL...NO MAJOR WHOLESALE CHANGES TO ONGOING FORECAST. TUESDAY EVENING A FAST-MOVING S/W TROUGH PROGGED TO BE LOCATED OVER INDIANA AND MOVING E/SE WARD. THE SFC FRONT STILL PROGGED TO BE LAGGING BEHIND...BUT IT APPEARS THAT A PREFRONTAL BAND WILL MOVE ACROSS THE AREA TUE EVE OUT AHEAD OF FRONT WITH S/W TROUGH. SOME INDICATION THAT THIS CONVECTIVE LINE WILL ARRIVE LATER THAN 00Z WED...PERHAPS MORE LIKE 03Z WED. KEPT INHERITED LIKELY POPS OVER THE SE OHIO ZONES HOWEVER AS THESE PROGRESSIVE SYSTEMS SEEM TO HAVE A WAY OF PROPAGATING MUCH QUICKER THAN THE SYNOPTIC SCALE FORCING WOULD INDICATE. MARGINAL SHEAR AROUND 25KTS AND ML CAPE VALS OF 1000-1500J/KG INDICATE THE POTENTIAL FOR STRONG STORMS...WITH A STORM OR TWO POSSIBLY REACHING SVR LIMITS...MAINLY OVER THE SE OHIO ZONES. STRONG WINDS WOULD BE THE PRIMARY HAZARD...BUT LARGE HAIL CAN/T BE COMPLETELY RULED OUT. THESE SHOWERS AND STORMS WILL LIKELY CONTINUE ACROSS THE AREA DURING THE EVENING AND INTO THE OVERNIGHT HOURS WITH SOME SFC INSTABILITY REMAINING EVEN DURING THE OVERNIGHT PERIOD...BUT THEY WILL BE WEAKENING AS THEY DO SO. BY WED...S/W TROUGH IS EXITING THE EASTERN MOUNTAINS AROUND 12Z WITH MAIN GENERAL AREA OF PRECIP EXITING WITH IT. SOMEWHAT DRIER AIR PUSHES IN AS WELL ON A W/NW FLOW ALOFT. SFC FRONT TO THE WEST CONTINUES TO MOVE EASTWARD BUT BECOMES MORE DIFFUSE ON ITS SOUTHERN END. WITH SOME LLVL MOISTURE REMAINING WITH PWATS UP AROUND THE 1.40IN-1.60IN RANGE HAVE CONTINUED LOW/MID CHANCE POPS BY WED AFTERNOON...WITH THE BETTER CHANCE FOR SHOWERS/STORMS BEING ACROSS THE FAR NORTHERN ZONES AS THE FRONT BRUSHES THAT AREA. SHOULD BE ANOTHER LULL IN OVERNIGHT PRECIP WED NIGHT BUT PRECIP CHANCES INCREASE FROM SW TO NE DURING THE DAY ON THURSDAY AS A WARM FRONT MOVES NORTHEAST...COINCIDENT WITH ANOTHER S/W TROUGH MOVING OVERHEAD DURING THE AFTERNOON HOURS IN THE FLOW ALOFT. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... SIDED GENERALLY WITH WPC THINKING FOR THE LONG-TERM PERIOD WITH A FEW TWEAKS BASED ON ENSEMBLE GUIDANCE. GENERAL PATTERN WILL BE CHARACTERIZED BY NORTHWEST FLOW ALOFT WITH PERSISTENT UPPER HIGH PARKED OVER THE SOUTHERN MISS VALLEY REGION AND LONGWAVE TROUGH OFF THE NORTHEAST COAST. HOWEVER...NAILING DOWN THE DETAILS AT THIS DISTANCE IN TIME IS DIFFICULT. AS SUCH...CONTINUE AT LEAST SLIGHT CHANCE POPS THROUGH THE ENTIRE PERIOD WITH THE HIGHEST CHANCE COMING THURSDAY NIGHT INTO FRIDAY MORNING AS A WARM FRONT LIFTS NORTHEAST. TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO REMAIN FAIRLY SEASONAL...WITH NO REAL HEATWAVES OR COOL PERIODS. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... IFR TO VLIFR BECOMING COMMON OVERNIGHT IN THE WAKE OF THE RAIN THAT ROLLED THROUGH ON MON. STRATUS WILL DOMINATE E WHILE DENSE FOG IS MORE DOMINATE IN THE W...BUT ALL SITES MAY SEE DENSE FOG BY THE TIME DAWN ROLLS AROUND. AFTER DAYBREAK...IT WILL TAKE THE BALANCE OF THE MORNING FOR THE STRATUS AND STRATOCU TO MIX THROUGH THE MVFR RANGE...AS THE FOG SLOWLY THINS INTO AN MVFR MIST. TUE AFTERNOON WILL TURN OUT VFR MOST SITES...EXCEPT MVFR STRATOCU HANGING ON IN THE MOUNTAINS. THE PROBLEM TUE NT WILL BE THUNDERSTORMS...WILL WILL FIRE UP IN THE MIDDLE OHIO VALLY AS A SYSTEM APPROACHES FROM THE NW. THE STORMS WILL MOVE QUICKLY SEWD TUE NT. LIGHT AND VARIABLE SFC FLOW WILL BECOME LIGHT SW TUE EVENING...WHILE LIGHT NW FLOW ALOFT BECOMES LIGHT W TUE AFTERNOON. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: LOW TO MEDIUM. ALTERNATE SCENARIOS: LOW STRATOCU AND STRATUS OVERNIGHT MAY CAUSE SFC VSBY TO OSCILLATE MORE THAN INDICATED IN FCST. TIMING OF AND CONDITIONS IN THUNDERSTORMS LATE TUE AND TUE NT MAY VARY. IFR IS POSSIBLE RIGHT BENEATH ANY THUNDERSTORMS. THE THUNDERSTORMS MAY ALSO PRODUCE STRONG WIND GUSTS. FOG COULD START TO FORM BY 06Z WED ESPECIALLY W...IF THE THUNDERSTORMS MOVE THROUGH QUICKLY ENOUGH. 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 TUE 08/19/14 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 L L L L L L L L M M M M HTS CONSISTENCY L L L L L L L L M M M M BKW CONSISTENCY M M H M H H H M M M H H EKN CONSISTENCY H H M H H H H H H M H H PKB CONSISTENCY H L L L L L L L H M M H CKB CONSISTENCY L L L L L L L L M H M M AFTER 06Z WEDNESDAY... IFR POSSIBLE IN ANY ROUND OF CONVECTION TUE NT THROUGH FRI NT...AND IN LATE NT/EARLY MORNING POST RAIN FOG AND STRATUS THROUGH SAT MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM NEAR TERM...KTB/TRM SHORT TERM...50 LONG TERM...50 AVIATION...TRM

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