Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 262336 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 636 PM EST FRI DEC 26 2014 .SYNOPSIS... HIGH PRESSURE MAINTAINS CONTROL INTO SATURDAY. A COLD FRONT CROSSES SATURDAY NIGHT AND SUNDAY. A WAVE OF LOW PRESSURE MOVES ALONG THE FRONT SUNDAY. DRIER...COLDER AIR SLOWLY BUILDS IN TO CLOSE OUT 2014. && .NEAR TERM /THROUGH SATURDAY/... SURFACE HIGH PRESSURE CENTERED OVER THE SOUTHEASTERN STATES WILL SHIFT EAST TONIGHT AND SATURDAY...ALLOWING A CONTINUING SOUTHERLY FLOW ACROSS THE AREA. WHILE THE AIR REMAINS RELATIVELY DRY IN THE LOWER LEVELS UNTIL LATER ON SATURDAY...MID TO UPPER LEVEL MOISTURE WILL BE INCREASING ON BROAD SOUTHWEST FLOW ALOFT AS A PROGRESSIVE UPPER TROUGH WELL TO OUR WEST SHIFTS EASTWARD. MODELS ARE IN BASIC AGREEMENT ON THE MASS FIELDS...BUT SATELLITE IMAGERY SHOWS THEY ARE LIKELY TOO SLOW IN ADVECTING THIS MID TO HIGH LEVEL MOISTURE INTO OUR AREA. MAIN DEVIATION TO THE MODELS WILL BE TO INCREASE CLOUDS FASTER LATER TONIGHT AND ESPECIALLY SATURDAY...AND IN TURN GO SLIGHTLY LOWER ON MAX TEMPS SATURDAY. NEVERTHELESS...TEMPS WILL STILL BE ABOVE NORMAL SATURDAY DESPITE THE CLOUD INCREASE. THE ATTENDING COLD FRONT REMAINS WELL TO THE WEST...WITH ONLY A SMALL CHANCE FOR RAIN OVER FAR WESTERN AND SOUTHWESTERN SECTIONS AT THE END OF THE PERIOD. TONIGHT WILL BE TRANQUIL WITH VERY LIGHT WINDS AND INCREASING MAINLY THIN HIGH CLOUDS...ALLOWING FOR RADIATIONAL COOLING TO DROP TEMPERATURES BELOW FREEZING AGAIN...BUT NOT AS COLD AS LAST NIGHT. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... PATTERN THIS PERIOD IS CHARACTERIZED BY FAST UPPER LEVEL FLOW THROUGH A CENTRAL CONUS L/W TROUGH...AND A TENACIOUS BAHAMA HIGH THAT SLOWLY FLATTENS. S/W TROUGH MINORS OUT AS IT LIFTS ENEWD OUT OF THE ROCKIES...AND CROSSES THE GREAT LAKES ON SAT. SECOND S/W TROUGH A LITTLE BEHIND THE FIRST ONE AND MORE IN THE SRN STREAM...ALSO MINORS OUT AS IF LIFTS ENEWD...REACHING THE TN VALLEY ON SUN AND THEN CROSSING THE APPALACHIANS SUN NT. THE S/W FIRST DRIVES A SW TO NE ORIENTED COLD FRONT INTO THE AREA SAT NT...AND THEN THE SECOND S/W PUSHES IT ON THROUGH ON SUN EVEN AS IT GENERATES A FLAT WAVE ALONG IT. RAIN SHOULD INCREASE FROM W TO E SAT NT AS THE FRONT MOVES THROUGH. THE NAM WAS THE FAST OUTLIER HERE...LEANED MORE TOWARD THE 09Z SREF...WHICH WAS CONSIDERABLY SLOWER. SUNDAY FIGURES TO BE A RAINY DAY THROUGHOUT THE AREA WITH THE APPROACHING S/W GENERATING THE FLAT WAVE ALONG THE FRONT CROSSING THE AREA. THE RAIN ONLY GRADUALLY MOVES OUT OF THE AREA SUN NT AND MON...AS THE UPPER LEVEL FLOW DOES NOT VEER MUCH BEHIND THE EXITING S/W TROUGH. HAVE TOTAL QPF WITH THIS PROLONGED EVENT RANGING FROM ALMOST AN INCH IN THE MOUNTAINS TO TWO DIMES IN OHIO...OFF RFC AND IN GENERALLY AGREEMENT WITH THE MODELS...ALTHOUGH THE CMC AND GFS HINT AT A SECOND MAXIMA ALONG THE OHIO RIVER. THE COLUMN MAY GET JUST COLD ENOUGH TO SUPPORT SNOW SFC AND ALOFT ON THE BACK SIDE OF THE PRECIPITATION SHIELD OVER THE MIDDLE OHIO VALLEY MON MORNING...AND IN THE WV MOUNTAINS VERY LATE MON...AS THE PRECIPITATION DIMINISHES TO A FEW SHOWERS AND / OR DRIZZLE THERE. THERE MAY BE A BRIEF OPPORTUNITY FOR SLEET OR FREEZING RAIN IN THE TRANSITION IF SUFFICIENTLY COLD AIR ARRIVES AT THE SFC BEFORE WE LOSE THE WARM NOSE ALOFT. THESE PRECIPITATION TYPES MAY EVENTUALLY NEED CODED IN EXPLICITLY DEPENDING UPON HOW MODELS RESOLVE CURRENT DIFFERENCES WITH TIMING AND THERMAL STRUCTURE. USED MAINLY NAM BASED SOURCES FOR TEMPERATURES...EXCEPT LATE MON WHERE THE INFLUENCE OF COLDER MODELS WAS ALLOWED IN. THE NAM DOES NOT SUPPORT SNOW IN THE MOUNTAINS THROUGH 84 HRS. IN THE MEANTIME...TEMPERATURES WILL BE STEADY OR SLOWLY FALLING SUN OVER THE MIDDLE OHIO VALLEY...IN THE WAKE OF THE FRONT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... OVERALL A FAIRLY QUIET LONG TERM PERIOD. HAVE POPS TAPERING OFF MONDAY NIGHT AS MOISTURE DEPARTS. BRING BACK IN SOME SLIGHT CHANCE POPS IN THE MOUNTAINS FOR LATE TUESDAY AND TUESDAY NIGHT WITH 850MB TEMPERATURE TROUGH AND WEAK 500MB SHORTWAVE TROUGH SLIDING THROUGH. HIGH PRESSURE NOSES IN FOR WEDNESDAY AND THURSDAY. BOTH GFS AND ECMWF SHOWING A SYSTEM MOVING OUT OF THE LOWER MISSISSIPPI VALLEY AT THE END OF THE WEEK...SO DO START INCREASING POPS RIGHT AT THE END OF THE PERIOD. BLENDED NEW WPC GUIDANCE INTO PREVIOUS FORECAST FOR TEMPS...AND THEN WENT JUST A TOUCH COOLER ON LOWS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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00Z SATURDAY THRU 00Z SUNDAY... HIGH PRESSURE WITH VFR CONDITIONS DURING THE PERIOD...ALTHOUGH MID AND HIGH CLOUDS WILL BE ON THE INCREASE OUT AHEAD OF AN APPROACHING COLD FRONT. CONDITIONS WILL REMAIN VFR THROUGH THE PERIOD WITH LIGHT SOUTHERLY WINDS. COLD FRONT AND ASSOCIATED PRECIPITATION WILL MOVE INTO SOUTHEAST OHIO TOWARDS 00Z SUNDAY...WITH ISOLD MVFR CONDITIONS FORMING THERE. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: HIGH. ALTERNATE SCENARIOS: NONE. 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 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 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 H H H 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 00Z SUNDAY... IFR POSSIBLE IN RAIN SUNDAY INTO MONDAY.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/JMV/MZ NEAR TERM...JMV/SL SHORT TERM...TRM LONG TERM...MZ AVIATION...SL

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