Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 201426 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1026 AM EDT SAT SEP 20 2014 .SYNOPSIS... HIGH PRESSURE MOVING OFF NORTHEAST COAST...ALLOWS SOUTHERLY FLOW TO BRING WARMER...BUT STILL MAINLY DRY WEATHER TODAY. A COLD FRONT CROSSES SUNDAY AFTERNOON. FALL HIGH PRESSURE DOMINATES NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... UPDATE... MID LEVEL INSTABILITY BRINGING SOME ALTOCUMULUS ALONG THE OHIO VALLEY...SO MADE SOME MINOR ADJUSTMENTS TO THE CLOUD FORECAST. OTHERWISE...LOOKING GOOD THIS MORNING. PREVIOUS DISCUSSION BELOW... UPSLOPE INDUCED LOW CLOUDS ALONG THE EASTERN SLOPES OF THE WV MOUNTAINS WERE BEGINNING TO ERODE FROM THE S AND W...A TREND THAT SHOULD CONTINUE TODAY AS THE FLOW CONTINUES TO VEER THROUGH S. THIS WARM ADVECTION VEERING WAS ALSO ASSOCIATED WITH A STRATOCU DECK FORMING TO THE W OF THE AREA IN THE THETA E AXIS. THIS MAY EVENTUALLY CONVERT AS SPOTTY SHOWERS W OF HTS LATER THIS MORNING. MODELS SUGGESTS SPOTTY FRONTOGENETIC FORCING INTO THIS AFTERNOON RIDING UP THE MIDDLE OHIO VALLEY WITH SUFFICIENT MOISTURE H85-H7 TO PERHAPS STAND UP A SHOWER...ALTHOUGH NEAR TERM MODELS DO NOT OUTPUT ANY RAINFALL AMOUNTS. OTHERWISE WILL HAVE A SCT-BKN CU / STRATOCU FIELD THIS AFTERNOON. CLOUDS INCREASE AS A COLD FRONT APPROACHES TONIGHT. LINE OF CONVECTION WAS NEARLY CO-LOCATED WITH ASSOCIATED COLD FRONT OVER THE MIDWEST EARLY THIS MORNING. HAVE CHC SHRA/TSRA ENTERING THE AREA FROM THE NW AROUND 06Z AND REACHING THE OHIO RIVER BY 12Z SUN IN ASSOCIATION WITH THIS FEATURE. THIS IS CLOSE TO MODELS WHICH HAVE COME CLOSER TOGETHER FOR THE NEAR TERM PERIOD. INSTABILITY BECOMES ELEVATED AS THUNDER ROLLS INTO THE AREA OVERNIGHT TONIGHT. HIGHS TODAY WERE CLOSER TO STRAIGHT GUIDANCE RATHER THAN THE LOWER BIAS CORRECTED OUTPUT. LITTLE CHANGE NEEDED OTHER THAN TO LOWER THE EASTERN SLOPES A BIT...WITH DOWNSLOPE SRLY FLOW W OF THE MOUNTAINS. BLENDED IN BIAS CORRECTED MET FOR LOWS TONIGHT AS THE MAV LOOKED TOO LOW ALL AROUND EVEN WITH A BIT LESS FLOW COMPARED WITH THIS MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... COLD FRONT ACROSS NORTHWEST OHIO AND CENTRAL INDIANA AT BEGINNING OF PERIOD...PUSHING EAST THROUGH THE CWA DURING THE DAY SUNDAY...AND TO THE EAST OF THE HIGHER TERRAIN BY SUNDAY NIGHT. NAM STILL THE SLOWER OF THE SOLUNS...BUT IS STARTING TO COME INTO BETTER AGREEMENT WITH FASTER GFS/ECMWF. CONTINUED TO LEAN FORECAST TOWARDS GFS SOLUN. COULD SEE ISOLATED STRONG WIND GUSTS SUNDAY AFTERNOON...MAINLY SOUTHEAST OHIO AND NORTHERN WV COUNTIES ON SUNDAY WITH ANY CONVECTION THAT DEVELOPS. SPC CONTINUES TO MAINTAIN A SEE TEXT OFF TO OUR NORTHEAST. UPPER TROUGH WILL SWING THROUGH THE AREA SUNDAY NIGHT/MONDAY...WITH CLOUDS...AND PERHAPS SOME LIGHT PRECIPITATION OR DRIZZLE LINGERING ACROSS THE CWA SUNDAY NIGHT INTO MONDAY...PARTICULARLY THE WV/SOUTHWEST VA ZONES. HELD ONTO CLOUD COVER ACROSS THE AFOREMENTIONED ZONES INTO MUCH OF THE DAY MONDAY...WITH HIGHER TERRAIN COUNTIES LAST TO CLEAR. HIGH PRESSURE WILL BUILD IN FOR TUESDAY FOR A RETURN TO DRIER WEATHER. && .LONG TERM /TUESDAY THROUGH FRIDAY/... MODELS SHOWING A FALL HIGH PRESSURE SYSTEM OVER THE REGION THROUGH THE PERIOD. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... THE AREA WILL BE IN A SRLY FLOW BETWEEN HIGH PRESSURE WELL TO THE E...AND A COLD FRONT APPROACHING FROM THE W. THIS WILL KEEP VFR CONDITIONS FOR THE MOST PART WITH SCT STRATOCU AOA 5 KFT...AND FLOW JUST STRONG ENOUGH TO PRECLUDE DENSE FOG IN MOST CASES. THERE ARE A FEW CAVEATS. MOISTURE IN S TO SE FLOW ALONG THE EASTERN SLOPES CONTINUES TO ERODE. IT STILL HAS ONE LAST CHANCE TO GET INTO BKW FOR A TIME THIS MORNING...ON MIXING AFTER SUNRISE. CIGS WOULD BE 1-2 KFT SHOULD IT OCCUR. EARLY MORNING LLJ AOA 3 KFT CLOSE TO 40 KTS BUT 20 KTS AT 2 KFT FROM RADAR. THIS 20 KT CHANGE OVER 2 KFT MAKES LLWS CRITERIA OF 20 KTS WITHIN A 200FT LAYER EXISTING WITHIN 2 KFT OF THE SFC VERY UNLIKELY. DENSE FOG MAY FORM LATE OVERNIGHT TONIGHT IN THE TYGART VALLEY / EKN / AHEAD OF THE CLOUDS APPROACHING FROM THE W...AS OFFSHORE HIGH PRESSURE RIDGES BACK INTO THE CENTRAL APPALACHIANS...ACTUALLY RESULTING IN LESS FLOW COMPARED WITH THIS MORNING. SFC FLOW WILL AVERAGE FROM THE S THROUGH THE PERIOD...A BIT GUSTY ON THE RIDGES AND HILLTOPS TODAY. THE WIND WILL TEND TO VEER TOWARD SW DURING TODAY AND BACK TOWARD SE TONIGHT...EXCEPT IT WILL VEER TOWARD SW LATE OVERNIGHT TONIGHT AS THE COLD FRONT APPROACHES. FLOW ALOFT WILL REMAIN MODERATE SW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: MVFR CIGS MAY NEVER FORM AT BKW THIS MORNING. BKW WINDS...GUSTY AT TIMES...MAY VARY FROM FCST TODAY. THE DENSE FOG CODED UP FOR LATE OVERNIGHT TONIGHT IN THE TYGART VALLEY / EKN / MAY NOT BE AS DENSE AS FCST. 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 14 15 16 17 18 19 20 21 22 23 00 01 EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 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 M M M H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z SUNDAY... BRIEF IFR CONDITIONS POSSIBLE SUNDAY IN SHOWERS/THUNDERSTORMS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM/26 SHORT TERM...SL LONG TERM...RPY AVIATION...TRM

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