Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 251024 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 620 AM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGES SOUTH FROM MID ATLANTIC STATES WITH DRIER AIR. FRONT ACROSS LOWER GREAT LAKES ON TUESDAY...TRIES TO SINK SOUTH LATE WEDNESDAY INTO OUR VICINITY...BEFORE WEAKENING BY THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... THE DRIER EASTERLY FLOW IS A BULLY. IT IS SHOWING THE MUGGY UNSTABLE AIR...WHO IS THE BOSS TODAY...AND SHOVING IT EVEN FURTHER WEST. FOR EXAMPLE...THE 925 MB DEW POINT WAS ABOUT 18C BACK AT 00Z ABOVE CRW. THE 00Z NAM HAS IT DOWN TO 12C BY 12Z THIS MORNING...BEFORE INCREASING BACK TO AROUND 15C. THE UPSLOPE CLOUDS ARE STILL THERE EARLY THIS MORNING...ALONG THE EASTERN SLOPES... BUT SHOULD CONTINUE TO DECREASE IN AREAL COVERAGE AS DRIER AIR CONTINUES TO ADVECT IN...REDUCING THE MEAN COLUMN RH. EVEN BKW HAD A HARD TIME KEEPING A CEILING OVERNIGHT. THE SOUTHEAST WIND FLOW AT 925 MB WAS STILL BLOWING AT 15 KNOTS AT 07Z AT RLX. FIGURING EARLY MORNING FOG RESTRICTED TO JUST SOME OF THE RIVER VALLEYS AS TEMPERATURES ARE COOLER THAN RECENT DAWNS. MEANWHILE...A WEAK 500 MB VORT MAXIMUM RIDING OVER THE RIDGE WAS IN WESTERN OHIO THIS MORNING...AND SHOULD REMAIN THERE WHILE WEAKENING TODAY. THOUGHT WE COULD PULL THE SLIGHT CHANCE POPS FOR CONVECTION ASSOCIATED WITH THAT FEATURE AND ITS LINGERING MOISTURE MAXIMUM.... A BIT FURTHER WEST...AND JUST OUT OF OUR FORECAST AREA FOR TODAY. THE GROUND/VEGETATION SHOULD SEE SOME GOOD DRYING THIS AFTERNOON... AS DEW POINTS DROP. SOME PREDAWN FOG TUESDAY IN THE COOLER AIR AND LESS LOW LEVEL FLOW. INCLUDED SOME MINIMUM TEMPERATURES 40S IN THE CENTRAL WV MOUNTAINS AND UPPER GREENBRIER VALLEY. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... HIGH PRESSURE IN PLACE...CENTERED OVER THE MOUNTAINS TO START THE SHORT TERM ON TUESDAY. A COLD FRONT WILL DROP SOUTH INTO THE GREAT LAKES TUESDAY...PASSING THROUGH OH/PA WEDNESDAY...AND THEN CROSSING CWA WEDNESDAY NIGHT. MODELS IN FAIR AGREEMENT...WITH TIMING OF THE FRONT ENTERING NW CWA LATE WEDNESDAY AFTERNOON...AND GRADUALLY DROPPING SOUTH AND DISSIPATING WEDNESDAY NIGHT. SLOWED DOWN POPS A TOUCH WEDNESDAY BASED ON MODEL TIMING. USED A CONSENSUS BLEND FOR HIGHS ON TUESDAY WITH LITTLE CHANGE. BLENDED IN BIAS CORRECTED ECMWF FOR WEDNESDAY HIGHS...COOLING THE NW A BIT WITH CLOUDS AND PRECIP INCOMING. BLENDED IN BIAS CORRECTED CONSENSUS GUIDANCE FOR LOWS...RESULTING IN A DEGREE CHANGE HERE AND THERE BUT NOTHING SIGNIFICANT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... SOME TIMING DIFFERENCES WITH COLD FRONT WEDNESDAY NIGHT INTO THURSDAY. MOST OF THE MODELS ALLOW THE FRONT TO SLIP S OF THE AREA EARLY THURSDAY. AS SUCH HAVE SOME POPS ALONG AND JUST AHEAD OF FRONT. FRONT BECOMES RATHER DIFFUSE NEAR THE AREA ON FRIDAY AS THE UPPER RIDGE BUILDS AGAIN INTO THE AREA THRU SATURDAY. WILL WATCH S/W TROF EJECTING OUT OF THE PLAINS APPROACH ON SUNDAY WITH AN INCREASE IN CHANCES FOR SHRA/TSRA. TEMPS WILL RUN CLOSE TO AVERAGE. && .AVIATION /10Z MONDAY THROUGH FRIDAY/...
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SO FAR...THE MOVE MADE BACK IN THE 06Z SET OF TAFS FOR LESS FOG IS PANNING OUT. THE COOLER MOUNTAIN VALLEYS STILL HAVE SOME THICK FOG...INCLUDING AROUND EKN. OVER THE HIGHEST MOUNTAIN RIDGES...SAY ABOVE 3500 FEET...SOME LOWER STRATUS COULD STILL HIT THE GROUND...CAUSING THICK FOG THROUGH 13Z MONDAY. ONLY SCATTERED CU FIGURED AT 3 TO 5 THSD TODAY. LARGE DEW POINT DEPRESSION LATE THIS AFTERNOON...SO ANY FOG THAT DOES FORM TONIGHT WILL BE LATE IN FORMING. BETWEEN 06Z TO 12Z TUESDAY...WITH WEAKER WIND FLOW AT 925 MB AND COOLER TEMPERATURES WILL HAVE SOME DENSE VALLEY FOG FORMING...MAINLY IN THE WEST VIRGINIA RIVER VALLEYS...WITH VSBY AOB 1 MILE AND SOME CEILINGS AROUND 2 THSD FT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z TUESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: WITH THE LARGE DEW POINT DEPRESSION LATE THIS AFTERNOON...IF ANY WIND STIRS OVERNIGHT...FOG COULD BE LESS 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. UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18 CRW CONSISTENCY H H M H H H H H H H H H HTS CONSISTENCY M M M H H H H H H H H H BKW CONSISTENCY M M H H H H H H H H H H EKN CONSISTENCY L L M H H H H H H H H H PKB CONSISTENCY M M M 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 TUESDAY... LOCAL IFR CONDITIONS POSSIBLE AGAIN IN RIVER VALLEY FOG EARLY WEDNESDAY MORNING.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/MZ NEAR TERM...KTB SHORT TERM...MZ LONG TERM...30 AVIATION...KTB

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