Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 211418 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1018 AM EDT SUN SEP 21 2014 .SYNOPSIS... A COLD FRONT CROSSES THIS AFTERNOON. AUTUMN HIGH PRESSURE BUILDS IN MONDAY NIGHT...AND THEN DOMINATES THE WEATHER OVER THE AREA THROUGH MUCH...IF NOT ALL...OF THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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1000 AM UPDATE... LINE HAS DEVELOPED AND IS MOVING THROUGH THE EASTERN CWA...BUT WITH LITTLE FANFARE. UPDATED THE POPS TO REFLECT THIS AND CURRENTLY AWAITING THE COLD FRONT AND THE CONVECTION FIRE WITH THE MAIN BOUNDARY. PREV DISCN... CONVECTION AHEAD OF A COLD FRONT CROSSING IN AND IL EARLY THIS MORNING STRUGGLING TO PUSH E AS INITIAL S/W TROUGH LIFTS OUT. AS A RESULT...CONVECTION HAS BECOME INCREASINGLY CONFINED TO AN AXIS JUST AHEAD OF THE FRONT. AS A RESULT...SHOWERS DO NOT REACH THE UPSTREAM /W/ EDGE OF THE FCST AREA UNTIL CLOSE TO DAYBREAK. MODELS ESPECIALLY NEAR TERM MODELS INSIST THE PRECIPITATION MOVES QUICKLY E ACROSS FCST AREA TODAY IN RESPONSE TO SECOND S/W TROUGH WHICH ALSO LIFTS OUT THIS MORNING...SO THIS PRECIPITATION MAY AGAIN STRUGGLE TO HOLD TOGETHER. POPS EVENTUALLY COME CLOSER IN LINE WITH PREV FCST AS FRONT AND WHATEVER DIURNAL HEATING WE CAN ACHIEVE CONVERGE ON THE FCST AREA THIS AFTERNOON BENEATH DIFFLUENT UPPER LEVEL FLOW AND FALLING HEIGHTS. SO NAM DYNAMICS SUGGEST AT LEAST TWO BANDS OF CONVECTION SWEEPING ACROSS WHILE WRFARW FOR EXAMPLE SUGGESTS SEVERAL. SEP HEATING AND CLOUD COVER EARLY ON WILL LIMIT INSTABILITY BUT CYCLONIC FLOW ALOFT HELPS PUSH MID LEVEL /H85-H7/ LAPSE RATES TO 6-7C/KM. FLOW IS ALSO MARGINAL WITH 30 KTS AT H85 AND 40 KTS MID LEVEL MEAN AND 60 KTS AT H5. WILL BE DIFFICULT BUT NOT IMPOSSIBLE TO CONVERT THIS TO DAMAGING WIND AT THE SFC BUT ISOLATED STRONGER GUSTS ARE POSSIBLE. THINK ANY DAMAGE IS MINOR AND ISOLATED ENOUGH FOR NO MENTION IN HWO AND NEAR TERM FCST. H7-H5 LAPSE RATES ARE LOWER OWING TO A STABLE LEVEL THERE SO HAIL IS NOT LIKELY DESPITE FREEZING LEVELS AS LOW AS 10 KFT AGL AND THE 60 KTS AT H5 WILL BE HARD TO TAP. SPC KEEPS PROBABILITIES AT 5 PERCENT ON BOTH IN A SEE TEXT. BRIEF CLEARING TAKES PLACE LATE TODAY AND TONIGHT IN THE WAKE OF THE FRONT...BUT CLOUDS INCREASE AGAIN OVERNIGHT IN THE CYCLONIC LOW LEVEL FLOW BENEATH THE POST FRONTAL INVERSION. CLOUD AND FLOW SHOULD PRECLUDE DENSE FOG TONIGHT ALTHOUGH SOME POST RAIN MIST AND LIMITED VALLEY FOG ARE LIKELY. MET AND MAV WERE A LITTLE HIGHER THAN PREV FCST ON TEMPERATURES BUT MADE JUST S SLIGHT MOVE IN THAT DIRECTION. THE TIMING ON HIGHS WILL VARY BASED ON THE MOVEMENT OF THE FRONT...BASICALLY EARLY E AND LATE W BUT DETAIL DIFFICULT TO CODE. MOVED TOWARD HIGHER GUIDANCE TONIGHT WITH THE TYPICAL SLOWER PUSH OF COOLER AIR TOWARD THE MOUNTAINS.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... COLD FRONT TO THE EAST OF THE AREA AT THE BEGINNING OF THE PERIOD...WITH UPPER TROUGH PUSHING EAST ACROSS THE CWA. STILL EXPECTING QUITE A BIT OF STRATUS LINGERING ACROSS THE CWA FOR AT LEAST THE FIRST PART OF MONDAY...WITH SOME LINGERING LIGHT PRECIPITATION POSSIBLE MONDAY MORNING. OTHERWISE...HIGH PRESSURE WILL GRADUALLY BUILD IN FROM THE WEST...WITH A GRADUAL CLEARING/DRYING TREND. WARMER TEMPERATURES EXPECTED BY TUESDAY INTO WEDNESDAY...AS UPPER HEIGHTS BUILD ACROSS THE EASTERN U.S. EXPECT A RIDGE/VALLEY TEMPERATURE SPLIT TUESDAY NIGHT/WEDNESDAY MORNING. && .LONG TERM /WEDNESDAY 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 /14Z SUNDAY THROUGH THURSDAY/...
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ANY REMAINING VALLEY FOG WAS BEING SCOURED OUT EARLY THIS MORNING...AS CLOUD AND WIND WERE INCREASING IN RESPONSE TO A COLD FRONT APPROACHING FROM THE W. THE FRONT WILL LIKELY BRING SHRA/TSRA TO THE OHIO RIVER NEAR 15Z...CRW AND CKB 16Z AND THE MOUNTAINS 16-17Z. THERE WILL BE ABOUT A 5 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 THIS EVENING WILL LIKELY BE 4-5 KFT MIDDLE OHIO VALLEY AND MVFR 2-3 KFT MOUNTAINS...BUT LOWER TO MVFR LOWLANDS OVERNIGHT AND EVENTUALLY AOA 1-2 KFT...WITH IFR IN THE MOUNTAINS...BY 12Z MON. POST-RAIN MVFR MIST MAY FORM AS WELL OVERNIGHT TONIGHT...BUT THE FLOW SHOULD REMAIN STRONG ENOUGH FOR ALL BUT IFR FOG IN A FEW BETTER SHELTERED VALLEYS. SW SFC FLOW TODAY...A BIT GUSTY THIS AFTERNOON...WILL BECOME W TO NW BEHIND THE FRONT LATE THIS AFTERNOON AND THIS EVENING...A BIT GUSTY INITIALLY. LIGHT TO MODERATE W TO SW FLOW ALOFT MOST OF TODAY WILL BECOME MODERATE NW TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: CONDITIONS IN SHRA/TSRA TODAY WILL VARY AS MAY MVFR STRATOCU CIGS FOLLOWING THE FRONT TONIGHT AND MVFR MIST AND IFR CIGS IN MOUNTAINS TOWARD DAWN MON. 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 M H H M M M M M H HTS CONSISTENCY M M M M M M M H H H H H BKW CONSISTENCY M M M M H H H H H M M M EKN CONSISTENCY M M M M H M M M M M M M PKB CONSISTENCY M M M M M M M H H H H H CKB CONSISTENCY H H H H H H M M H H H H AFTER 12Z MONDAY... IFR STRATUS POSSIBLE MON MORNING...ESPECIALLY IN THE MOUNTAINS. IFR VALLEY FOG POSSIBLE TUE MORNING...ESPECIALLY ALONG RIVERS AND IN BETTER SHELTERED VALLEYS.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM/26 SHORT TERM...SL LONG TERM...JMV AVIATION...TRM

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