Area Forecast Discussion
Issued by NWS Charleston, WV

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855 FXUS61 KRLX 180308 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1100 PM EDT SUN MAY 17 2015 .SYNOPSIS...
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WEAK DISTURBANCES IN WARM MOIST AIR MASS WILL RESULT IN PERIODS OF SHOWERS AND THUNDERSTORMS MONDAY INTO MONDAY NIGHT. A COLD FRONT CROSSES TUESDAY...EAR;U ENOUGH FOR AFTERNOON DRYING.
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&& .NEAR TERM /THROUGH MONDAY/...
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1100 PM UPDATE... EVENING CONVECTION HAS WANED...AND UPSTREAM MCV HAS ALSO WEAKENED...ESPECIALLY THE NRN PART OF IT. THEREFORE THIS IS MUCH LESS LIKELY TI IMPACT FCST AREA OVERNIGHT. VALLEY FOG HAS STARTED TO FORM IN AREAS AFFECTED BY EARLIER CONVECTION...INCLUDING EKN...CRW AND PROBABLY WILL AT CKB AS WELL WITH TEMPERATURES A LITTLE LOWER AND DEW POINTS A LITTLE HIGHER THAN EARLIER. STILL NO CHANGES TO MON WITH POPS INCREASING EARLY ON S/W ENERGY THAT TRIGGERED THE UPSTREAM MCV EARLIER.. 800 PM UPDATE... KNOCKED POPS DOWN TO SCHC LOWLANDS/CHC MOUNTAINS OVERNIGHT AS LATE DAY CONVECTION HAS ALREADY WANED. ONE CAVEAT IS MCV COMING OUT OF THE TN VALLEY...WHICH MAY APPROACH THE HTS TRI STATE AREA AS MIDNIGHT APPROACHES...BEFORE FALLING APART. NO CHANGES MADE FOR MON...WHEN AN EARLY W TO E INCREASE IN POPS REFLECTS UPPER LEVEL S/W TROUGH WHICH INSTIGATED THE UPSTREAM MCV. IT MAY TRIGGER NEW CONVECTION JUST UPSTREAM OF THE FCST AREA TOWARD DAWN MON. PREV DISCN... STILL A CHALLENGING DETERMINISTIC HOURLY FORECAST...AS FREQUENTLY IS THE CASE DURING THE SUMMER MONTHS. IN THE MID MORNING SUNDAY UPDATE...WE THOUGHT THERE WOULD BE MORE CONVECTION FORMING OVER SOUTHERN COUNTIES OF OUR CWA EARLY THIS AFTERNOON...WITH THE WEAK 500 MB VORT MAX LIFTING OUT OF TENNESSEE. AS OF 1745Z...THAT HAS NOT BE THE CASE SO FAR. THE NORTHERN DISTURBANCE DID MOVE OUT ON SCHEDULE...BUT SMALL CONVECTION FORMED QUICKLY IN CENTRAL WV. SCATTERED CONCENTRATED DOWNPOURS FORMED MAINLY IN CENTRAL AND NORTHERN COUNTIES DURING THE EARLY AFTERNOON. WILL CONTINUE THESE INTO THE EVENING BEFORE WANING. AREAS OF FOG POSSIBLE IN WV. MORE 925 MB FLOW IN SOUTHEAST OHIO SHOULD LIMIT THE FOG THERE. STILL HAVE POPS INCREASING AGAIN AROUND DAWN IN THE OHIO VALLEY COUNTIES...THEN ELSEWHERE AFTER DAWN. WILL NOT MAKE MANY CHANGES TO THE PREVIOUS POPS...SINCE NOTHING TO FOCUS ON AT THIS POINT. NAM FORECAST SOUNDING MAY BE A BIT MORE UNSTABLE THAN SUNDAY...IN THE SKINNY CAPE...BUT FLOW STILL WEAK. STILL THINKING THE LOCALIZED DOWNPOURS ARE THE MAIN CONCERN ON MONDAY...COMPARED WITH THE SEVERE THREAT. IN PAST 24 HOURS...A FEW SEPARATE MAXIMUM AREAS IN THE CONVECTION OF AROUND AN INCH...BUT OVERALL WE CAN STILL HANDLE 1 TO 2 INCHES DOWNPOURS AT THIS TIME...WITH THE USUAL STREET FLOODING. HOWEVER...WE STILL NEED TO WATCH HOW THIS ALL UNFOLDS NEXT 36 HOURS...AHEAD OF THE COLD FRONT.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... MADE NO REAL CHANGES WITH THE SHORT TERM PART OF THE FORECAST. RAISED POPS A BIT IN THE EAST MONDAY NIGHT AHEAD OF THE COLD FRONT. PW VALUES ARE IN THE 1.5-1.75 INCHES RANGE AHEAD THE FRONT SO THE PROSPECT OF HEAVY RAIN OVERNIGHT IS STILL POSSIBLE. EVEN WITH ALL OF THE RAIN THAT HAS FALLEN UP TO THIS POINT THE GROUND SHOULD BE ABLE TO HANDLE THE SITUATION SO NO REAL CONCERNS. WILL CONTINUE TO MONITOR THE SITUATION. IT DRIES OUT QUICKLY BEHIND THE FRONT STARTING TUESDAY NIGHT. DRY WEATHER WITH PLEASANT TEMPERATURES SHOULD PREVAIL TUESDAY NIGHT AND WEDNESDAY AS WEAK HIGH PRESSURE BUILDS TO THE WEST GIVING ZONAL FLOW FOR THE OHIO VALLEY. WENT MAINLY WITH ALL BLEND GUIDANCE FOR TEMPERATURES THROUGH THE PERIOD. && .LONG TERM /THURSDAY THROUGH SUNDAY/... NOTHING SIGNIFICANT TO FOCUS ON IN THE LONG TERM. HIGH PRESSURE BUILDS OVER THE CENTRAL US AND THAT WILL LEAVE ZONAL FLOW OVER THE OHIO VALLEY. THE EXTENDED FORECAST WILL BE DRY FOR THE MOST PART BUT CONFIDENCE IS NOT ALL THAT HIGH AS THERE COULD BE A FEW UPPER LEVEL RIPPLES CAUSED BY THE WEAK FRONT THAT PASSES TO THE NORTH NEXT WEEKEND. PRECIPITATION CHANCES INCREASING ON SUNDAY. WENT WITH A BLEND OF GUIDANCE FOR TEMPERATURES. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... CONVECTION WAS MOVING OFF TO THE E AND QUICKLY FADING AS 00Z APPROACHED. ONE CAVEAT IS AN MCV COMING OUT OF THE TN VALLEY...WHICH MAY APPROACH THE HTS TRI STATE AREA TOWARD MIDNIGHT TONIGHT...BEFORE FALLING APART. HOWEVER...THE UPPER LEVEL S/W TROUGH THAT GENERATED THIS FEATURE MAY GENERATE ADDITIONAL CONVECTION TOWARD DAWN MON THAT THEN MOVES ACROSS THE MIDDLE OHIO VALLEY AND CENTRAL APPALACHIANS MON MORNING AND MIDDAY. ANY THUNDERSTORM CAN PRODUCE MVFR TO IFR CONDITIONS. IN THE HUMID AIR...CIGS AROUND 2 TO 3 THSD FT WILL B MORE COMMON MON MORNING...EVEN OUTSIDE THE SHOWERS AND STORMS. OTHERWISE SOME FOG WILL FORM IN THE VALLEYS...MAINLY E OF THE OHIO RIVER...TOWARD DAWN MON. LIGHT AND VARIABLE SFC FLOW OVERNIGHT WILL BECOME LIGHT SW MON...LIGHT W IN THE MOUNTAINS. LIGHT SW FLOW ALOFT WILL BECOME LIGHT W TO NW OVERNIGHT AND THEN REMAIN SO INTO MON AFTERNOON. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: COVERAGE OF FOG IN WAKE OF LATE AFTERNOON AND EVENING SHOWERS/STORMS IS IN QUESTION OVER WEST VIRGINIA FOR 06Z TO 12Z MON. HIGHLY VARIABLE CONDITIONS IN THE SHOWERS AND STORMS MON WITH CONDITIONS GOING LOWER THAN 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 MON 05/18/15 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H M M H L L L L HTS CONSISTENCY H H H H H H H H M M M H BKW CONSISTENCY H H H H H M M H H H H H EKN CONSISTENCY H H H H H M L L L H H H PKB CONSISTENCY H H H H H H H H M M M M CKB CONSISTENCY H H H H H M M M L L L L AFTER 00Z TUESDAY... BRIEF IFR IN SHOWERS AND THUNDERSTORMS POSSIBLE MON AFTERNOON AND NT...AND IN LOW CLOUDS TUE MORNING. FOG/LOW CLOUDS POSSIBLE OVERNIGHT TUE NT INTO WED MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...FB/KTB/TRM NEAR TERM...KTB/TRM SHORT TERM...FB LONG TERM...FB AVIATION...TRM

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