Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 210611 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 211 AM EDT SUN SEP 21 2014 .SYNOPSIS... COLD FRONT SUNDAY. FALL HIGH PRESSURE DOMINATES NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... 200 AM UPDATE... HELD OFF ARRIVAL OF SHOWERS AND THUNDERSTORMS FROM THE WEST OVERNIGHT BY A COUPLE OF HOURS...OTHERWISE FCST ON TRACK. PREV DISCN... THE LEADING EDGE OF THE INCOMING FRONTAL SYSTEM WILL REACH THE NORTHWESTERN BOUNDARY OF THE FORECAST AREA AROUND 4 OR 5 AM SUNDAY MORNING. PRECIPITATION WILL THEN SPREAD EAST COVERING MUCH OF THE AREA BY MID TO LATE MORNING. IT DOES LOOK LIKE THE SOMEWHAT STRONGER ENERGY ASSOCIATED WITH THE FRONT WILL SPLIT TO THE NORTH AND SOUTH WITH THE WETTER SHOWERS AND THUNDERSTORMS GENERALLY CROSSING OVER THE SOUTHERN AREAS. THE NAM IS GENERATING SOME INTERESTING POST FRONTAL BANDING STRUCTURE SUNDAY AFTERNOON AND EVENING THAT WILL BE WORTH KEEPING AN EYE ON BUT WITH GENERALLY UNIMPRESSIVE CONVECTIVE PARAMETERS WOULD EXPECT TO SEE MAINLY SUB SEVERE GUSTS OUT OF THUNDERSTORMS BOTH WITH AND JUST BEHIND THE FRONT. WILL SEE SOME BRIEF PARTIAL CLEARING COMING IN FROM THE WEST LATE SUNDAY EVENING BUT WITH ANOTHER SHORTWAVE ROTATING THROUGH EXPECT TO SEE STRATUS REINFORCED AND ISOLATED TO SCATTERED SHOWERS PERSISTING ESPECIALLY IN THE EASTERN MOUNTAINS OVERNIGHT. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... MODELS HAVE A PROGRESSIVE UPPER TROUGH SWINGING THRU THE AREA SUNDAY NIGHT AND MONDAY. THE ASSOCIATED MAIN FRONT AND PRECIPITATION BAND AHEAD OF THE UPPER TROUGH WILL EXIT THE MOUNTAINS EARLY SUNDAY NIGHT. THERE IS A SECONDARY FRONT THAT DROPS DOWN DURING SUNDAY NIGHT...WITH SOME DECENT COLD ADVECTION BEHIND IT. THIS WILL ISSUE IN THE TYPICAL POST FRONTAL STRATUS SUNDAY NIGHT AND LAST INTO MUCH OF MONDAY. IT APPEARS THE DEEPER MOISTURE WRAPPING AROUND THE DEPARTING FRONT WILL STAY MAINLY NORTH OF THE AREA...SO ANY POST FRONTAL SHOWERS IN THE LOW LANDS SHOULD BE CONFINED TO THE NORTH BEFORE SWINGING RAPIDLY EASTWARD DURING SUNDAY NIGHT. THUS...WILL HAVE SLIGHT CHANCE POPS NORTH SUNDAY NIGHT. OTHERWISE...WILL LINGER BETTER POPS IN THE NORTHERN AND CENTRAL MOUNTAINS SUNDAY NIGHT...AIDED BY COLD ADVECTION UPSLOPE...BUT EVEN THIS WILL END BY MONDAY MORNING AS MOISTURE DEPTH DECREASES THERE. THIS WILL LEAVE THE STRATUS FOR MONDAY THAT WILL SLOWLY BREAK UP FROM WEST TO EAST MONDAY AS HIGH PRESSURE AND LOW LEVEL DRIER AIR QUICKLY SETTLES IN. FOR MONDAY NIGHT...CLEAR SKIES WILL BE THE RULE WITH WINDS GOING LIGHT UNDER THE HIGH PRESSURE...RESULTING IN A QUITE CHILLY NIGHT...WITH EVEN A FEW MID 30S IN THE MORE PROTECTED NORTHERN MOUNTAIN VALLEYS BY TUESDAY MORNING. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... NOT MUCH GOING ON AS THE SURFACE HIGH CONTINUES UNDER A DEVELOPING EASTERN U.S. UPPER RIDGE. THIS WILL BRING DRY AIR WITH LOTS OF SUNSHINE FOR THE REMAINDER OF THE WORK WEEK. THE RESULT HERE WILL BE A LARGE RANGE IN DIURNAL TEMPERATURES...BUT A DEFINITE WARMING TREND FROM HIGHS IN THE 60S MONDAY TO AROUND 80 BY FRIDAY. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... WITH WEAKER LOW LEVEL FLOW COMPARED WITH FRI NT...THE BOUNDARY LAYER HAS DECOUPLED IN THE VALLEYS. THIS ALLOWS IFR TO AT TIMES VLIFR DENSE FOG IN THE TYGART VALLEY / EKN / OVERNIGHT...WITH MVFR AT TIMES ELSEWHERE EXCEPT PKB / TO CLOSE TO APPROACHING FRONT / AND BKW / SOME WIND ON THE RIDGE /. ANY FOG WILL BURN OFF QUICKLY AFTER DAYBREAK IF NOT BEFORE...AS THE FRONT AND ITS ASSOCIATED INCREASE IN CLOUD AND FLOW APPROACH. THE FRONT WILL LIKELY BRING SHRA/TSRA TO THE OHIO RIVER NEAR 14Z...CRW AND CKB 15Z AND THE MOUNTAINS BY 16Z. THERE WILL BE ABOUT A 6 HOUR PERIOD AT MOST SITES DURING WHICH SHRA/TSRA ARE POSSIBLE AND IT WILL LIKELY COME IN TWO OR THREE BROKEN BANDS. THE FRONT WILL CROSS THE MIDDLE OHIO VALLEY AROUND 00Z AND THE MOUNTAINS 01-02Z. STRATOCU FOLLOWING THE FRONT SUNDAY EVENING WILL LIKELY BE 4-5 KFT MIDDLE OHIO VALLEY AND MVFR 2-3 KFT MOUNTAINS. LIGHT S SFC FLOW OVERNIGHT WILL BECOME SW SUN...A BIT GUSTY IN THE AFTERNOON...AND THEN W TO NW BEHIND THE FRONT LATE SUN AND SUN EVENING...A BIT GUSTY INITIALLY. LIGHT TO MODERATE W TO SW FLOW ALOFT OVERNIGHT AND MOST OF SUNDAY WILL BECOME MODERATE NW SUN NT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: FOG TIMING AND DENSITY IN QUESTION OVERNIGHT DEPENDING ON THE ARRIVAL TIME OF FRONTAL CLOUDS. IF CLOUDS WERE TO SLOW...THEN RIVER VALLEY FOG COULD BE DENSER AND MORE WIDESPREAD. CONDITIONS IN SHRA/TSRA SUNDAY WILL VARY AS MAY MVFR STRATOCU CIGS FOLLOWING THE FRONT SUNDAY EVENING. 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 09/21/14 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 H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H M M M M BKW CONSISTENCY H H H H H H M M M M M M EKN CONSISTENCY L L L L L L L L M M M M PKB CONSISTENCY H H M M M M M H M M M M CKB CONSISTENCY H H H H H M H H H H H M AFTER 06Z MONDAY... IFR STRATUS POSSIBLE MON MORNING...ESPECIALLY IN THE MOUNTAINS. IFR VALLEY FOG POSSIBLE TUE MORNING...ESPECIALLY ALONG RIVERS AND IN BETTER SHELTERED VALLEYS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/26 NEAR TERM...TRM/JR SHORT TERM...JMV LONG TERM...JMV AVIATION...TRM

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