Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 180815 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 414 AM EDT SAT APR 18 2015 .SYNOPSIS... WEAK HIGH PRESSURE FADES TODAY. WARM FRONT CROSSES THIS EVENING. A COLD FRONT CROSSING MONDAY HERALDS A PERIOD OF COOLER WEATHER...AS IT IS FOLLOWED BY ANOTHER WEDNESDAY NIGHT OR THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... UPPER LEVEL RIDGE CROSSES TODAY AND SHIFTS E OF THE AREA TONIGHT...AS NRN AND SRN UPPER LEVEL S/W TROUGHS APPROACH FROM THE W. THE NRN STREAM ONE DIGS INTO ND BY 12Z SUN WHILE THE SRN STREAM FEATURE...A CLOSED LOW COMING OUT OF THE FOUR CORNERS REGION EARLY THIS MORNING...OPENS UP AS IT TRAVERSES THE SRN PLAINS TONIGHT. SFC LOWS ARE FOUND E OF EACH UPPER FEATURE...BUT A WARM WAVE LOW ALSO FORMS OUT AHEAD OF THE SRN STREAM FEATURE OVER THE DEEP S LATER TODAY AND REACHES THE MID MISSISSIPPI VALLEY BY 12Z SUN...IN RESPONSE TO A LEAD S/W TROUGH AXIS AHEAD OF THE MAIN SRN STREAM TROUGH. AT THE SFC...WEAK HIGH PRESSURE OVER THE CWA THIS MORNING FADES AS A STRONGER HIGH BUILDS SEWD INTO ERN CANADA...AND DRIVES A BACK DOOR COLD FRONT DOWN THE E COAST. IT...AND THE WARM WAVE APPROACHING FROM THE W...INCREASES THE SE GRADIENT OVER THE CWA OVERNIGHT TONIGHT. SOMEWHAT DRIER AIR MANAGED TO FILTER DOWN THE MIDDLE OHIO VALLEY BUT DEW POINTS REMAIN HIGH IN AND NEAR THE CENTRAL APPALACHIANS. THIS RESULTED IN DENSE VALLEY FOG E OF THE OHIO RIVER EARLY THIS MORNING...WHICH MAY LIFT INTO STRATUS AND THEN MORNING CU. THIS SHOULD THEN MIX OUT...BUT EXPECT ELEVATED HEAT SOURCE CU TO FORM OVER THE MOUNTAINS THIS AFTERNOON. DRY MID LEVELS SHOULD PREVENT ANYTHING FARTHER DESPITE WEAK CONVERGENCE OVER THE MOUNTAINS...BUT THE CU MAY TOWER A LITTLE OVER THE SRN MOUNTAINS. INCREASING CLOUD AND PRESSURE GRADIENT SHOULD PRECLUDE FOG FORMATION TONIGHT. MODELS ARE IN GOOD AGREEMENT ON PRECIPITATION REACHING FAR SRN PORTIONS OF THE CWA BY 12Z SUN...INCREASED POPS TO LIKELY FOR SW VA AND CHANCE ALONG THE TUG FORK...AS A WARM FRONT EXTENDING ESEWD FROM THE WARM WAVE...APPROACHES FROM THE S. CLUSTERED GUIDANCE SUGGESTED SLIGHTLY HIGHER HIGHS FOR TODAY WHILE BLENDING IN OF CLUSTERED BIAS CORRECTED GUIDANCE YIELDED HIGHER LOWS FOR TONIGHT AS THE CLOUD AND WIND INCREASE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... ACTIVE WEATHER IN THE SHORT TERM PERIOD. GOOD SOUTHEASTERLY FLOW WILL DEVELOP ACROSS THE AREA ON SUNDAY AS A SURFACE LOW AND NEGATIVELY TILTED UPPER TROUGH LIFT NORTHEAST ACROSS THE MIDWEST. EXPECTING RATHER GUSTY WINDS TO DEVELOP ON SUNDAY...AS PRESSURE GRADIENT TIGHTENS...AND LLJ STRENGTHENS ACROSS THE REGION...WITH HIGHER GUSTS EXPECTED ACROSS THE MOUNTAINOUS COUNTIES. STILL AT THIS POINT NOT TOO WORRIED ABOUT FLOODING ISSUES...ALTHOUGH THIS WILL BE A RATHER DECENT SOAKER SUNDAY INTO MONDAY...PARTICULARLY ACROSS THE MOUNTAINOUS COUNTIES IN THE SOUTHEASTERLY UPSLOPE FLOW ON SUNDAY...AND AS A SECONDARY WAVE OF LOW PRESSURE RIDES NORTHEAST ACROSS THE MOUNTAINS. SURFACE COLD FRONT...AND UPPER WAVE WILL THEN MOVE THROUGH THE REGION ON MONDAY...FOR ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS. THERE IS THE POSSIBILITY OF A STRONG STORM MAINLY ACROSS THE SOUTH AND EAST...BUT THIS STILL REMAINS RATHER UNCERTAIN. FOR TEMPERATURES ON SUNDAY...LOWERED SLIGHTLY FROM PREVIOUS FORECAST DUE TO EXPECTED CLOUD COVER AND RAIN...BUT DID KEEP THE WV LOWLANDS WARMER DUE TO THE SOUTHEASTERLY DOWNSLOPING FLOW. COOLER AND UNSETTLED WEATHER THEN TAKES HOLD FOR MID WEEK AS UPPER LOW LINGERS ACROSS GREAT LAKES REGION. && .LONG TERM /TUESDAY THROUGH FRIDAY/... COLD FRONT WILL BE EAST OF THE CWA TO START THE LONG TERM...AND HAVE DECREASING POPS MONDAY NIGHT. SLOW MOVING UPPER LEVEL LOW PASSES TO OUR NORTH THROUGH THE WEEK WITH SEVERAL IMPULSES IN THE WEST TO NORTHWESTERLY FLOW...AND HAVE SOME PERIODS OF CHANCE POPS. MODELS ALSO SHOWING A COLD FRONT WEDNESDAY INTO THURSDAY. WITH SOME TIMING DIFFERENCES...BLENDED IN WPC GUIDANCE. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... SFC DEW POINTS WERE LEFT RATHER HIGH THROUGHOUT MUCH OF THE AREA OWING TO THE LACK OF A DRY PUSH FROM THE N. DRIER AIR DID MANAGE TO FILTER DOWN THE MIDDLE OHIO VALLEY WHILE HIGHER DEW POINTS REMAINED POOLED NEAR THE MOUNTAINS. THUS PKB STARTS OUT 59/50 WHILE CKB BEGINS 55/54 WITH IFR FOG ALREADY. CIRRUS IS ALSO ACTING AGAINST THE FOG BUT WAS THIN ENOUGH TO ALLOW DENSE FOG ON AND OFF AT EKN ALL THE WAY BACK AT 02Z AND MORE PERSISTENT DURING THE PAST HR. TIMED DENSE FOG THROUGH 12Z THERE WHILE ALLOWING IFR FOG CKB THROUGH 11Z. FARTHER S MVFR STRATOCU MAY FORM AND INTERFERE WITH FOG FORMATION BUT LEANED MORE TOWARD THE FOG IDEA. HAVE IFR TIMED 10Z THROUGH 11Z CRW. LEFT IFR OUT ALONG THE OHIO RIVER. VFR DAY SAT ONCE THE FOG BURNS OFF QUICKLY AFTER 12Z AND AFTER SOME MORNING CU MIXES OUT. AFTERNOON CU WILL FORM OVER THE HIGHER TERRAIN. VFR SAT NT WITH SOME INCREASE IN MAINLY HIGH CLOUD. CALM AIR OVERNIGHT EXCEPT A LIGHT FLOW DOWN THE OHIO RIVER. LIGHT N TO NE SFC FLOW SAT MIDDAY AND AFTERNOON WILL BECOME LIGHT E TO NE SAT NT. LIGHT N TO NW FLOW ALOFT WILL BECOME LIGHT NE SAT AND LIGHT SE SAT NT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: LOW TO MEDIUM. ALTERNATE SCENARIOS: FOG AND LOW STRATUS TIMING/COVERAGE/THICKNESS MOSTLY 06Z TO 12Z SATURDAY COULD VARY GREATLY IN WEST VIRGINIA FROM DETERMINISTIC 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 SAT 04/18/15 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 M M L L L M M H H H H HTS CONSISTENCY H H M M M M H H H H H H BKW CONSISTENCY M H H M M M M M M M M H EKN CONSISTENCY L L L L L L L L H H H H PKB CONSISTENCY H H M M M M M H H H H H CKB CONSISTENCY M M L L L L L M H H H H AFTER 06Z SUNDAY... IFR POSSIBLE IN MOSTLY SHOWERS SUNDAY AFTERNOON INTO SUNDAY NIGHT...AND SHOWERS OR THUNDERSTORMS MONDAY INTO MONDAY EVENING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...MZ AVIATION...TRM

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