Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 201846 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 246 PM EDT MON APR 20 2015 .SYNOPSIS...
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A COLD FRONT CROSSES BY THIS EVENING...AS A LARGE LOW PRESSURE SYSTEM MOVES NORTH INTO CENTRAL CANADA. ANOTHER COLD FRONT CROSSES WEDNESDAY NIGHT INTO THURSDAY. COOLER WEATHER REMINDER OF THE WEEK,
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&& .NEAR TERM /THROUGH TUESDAY/... SURFACE COLD FRONT JUST STARTING TO APPROACH WESTERN PORTION OF THE FORECAST AREA...AND WILL TRACK EAST THROUGH THE EARLY EVENING HOURS WITH ASSOCIATED CONVECTIVE ACTIVITY. SEEING SOME ENHANCEMENT OF CU FIELD IN VISIBLE SAT IMAGERY INVOF OF FRONT WITH CONVECTION BEGINNING TO SHOW ONLY THE SLIGHTEST SIGN OF GAINING SOME LINEARITY IN ITS STRUCTURE. ATMOSPHERE IS ONLY MARGINALLY UNSTABLE AHEAD OF FRONT ACROSS WV AND SW VA. SFC DEWPOINTS INDICATED CONSIDERABLE MIXING OF THE LOWER BOUNDARY LAYER HAS OCCURRED OVER A BROAD SWATH OF WV. THUS...WE EXPECT A FAIRLY SLOW DEVELOPMENT PHASE TO CONVECTION ACROSS THE WESTERN PORTION EARLY THIS AFTERNOON...WITH MORE ENHANCED ACTIVITY LATE THIS AFTERNOON AND EARLY EVENING ACROSS THE FAR EASTERN MOUNTAINS. FRONT EXITS TONIGHT AND ATMOSPHERIC COLUMN WILL SEE A DRYING TREND WITH COOLER TEMPS. STARTED WITH INHERITED TEMP VALUES AND BLENDED IN MINOR TWEAKS. GUSTY WINDS CONTINUE INTO TUESDAY. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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MODELS SHOW AN ELONGATED MID LEVEL WAVE PASSING TO OUR WV/PA BORDER TUESDAY NIGHT. AT THE SFC...THE NAM SHOWS A COMPACTED CLOSED LOW MOVING ACROSS THE OH VALLEY...NORTHEAST INTO PA. ITS ASSOCIATED COLD FRONT COULD BRING RAIN SHOWERS...MORE PREVALENT OVER THE NORTHERN SECTIONS. THE CMC AND GFS JOINT THIS SOLUTION IN THEIR QPF FIELDS. THEREFORE...INCREASE POPS TO LIKELY DURING THE PREDAWN HOURS WEDNESDAY WITH MORE COVERAGE ACROSS THE NORTHERN COUNTIES THROUGH WEDNESDAY AFTERNOON. MODELS SHOW LIMITED THERMODYNAMIC INSTABILITY AND HIGH DEEP LAYERED SHEAR. HOWEVER...DO TO THE TIME OF THE FRONTAL PASSAGE AND THE WEAKNESS OF THIS FEATURE...KEEP THUNDER MENTION OUT FROM FORECAST FOR NOW. THE FRONT WILL PUSH ALL SHOWERS EAST SOUTHEAST BY WEDNESDAY EVENING. MODELS SHOW H850 FREEZING LEVEL CROSSING THE AREA FROM NORTHWEST TO SOUTHEAST. THEREFORE...EXPECT TEMPERATURES TO DROP INTO THE MID TO UPPER 50S LOWLANDS...RANGING INTO THE MID 40S HIGHER ELEVATIONS. COLD AIR ADVECTION CONTINUES WEDNESDAY NIGHT PERHAPS BRINGING SOME FROST MAINLY NORTHERN AND HIGHER ELEVATIONS AREAS. DRIER CONDITIONS EXPECTED ON THURSDAY AS A DRIER AIR MASS REMAINS IN PLACE. WENT CLOSER TO THE MOS CONSENSUS ALL WITH SOME TWEAKS THROUGH THE PERIOD.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THANKFULLY...THE DRIER AND COOLER PATTERN APPEARS TO CONTINUE. WITH TROFS OFF NORTHWEST COAST AND OVER NEW ENGLAND AND NORTHEAST COAST. THE LACK OF DEEPER MOISTURE IS CERTAINLY WELCOMED. STILL FAST MOVING MID LEVEL DISTURBANCES IN THE WNW STEERING FLOW THAT CAUSES PROBLEMS HERE WITH DETERMINISTIC POPS HERE. WAS DRIER FOR THE START OF THIS LONG TERM...THINKING WEDNESDAY`S WEAK SYSTEM WILL BE EXITING WEDNESDAY EVENING. MEDIUM RANGE GUIDANCE FROM WPC INTRODUCED LKLY POPS SATURDAY...BUT WILL HAVE JUST CHANCE POPS WORKING NORTH SATURDAY. CONFIDENCE IN TIMING SOUTHERN MOISTURE MOVING NORTH IS LOW. STRATOCUMULUS CLOUD IN THE COOLER FLOW AND WIND LIKELY TO MESS WITH OUR FORECAST LOW TEMPERATURES...BUT HAVE 30S AND LOWER 40S FOR SEVERAL NIGHTS...FOR DAWN FRIDAY...SATURDAY...AND SUNDAY. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... COLD FRONT WITH ASSOCIATED CONVECTION MOVING INTO CENTRAL OH...WILL CONTINUE ITS TRACK TO THE EAST THROUGH THE FIRST HALF OF THE TAF PERIOD. HAVE FROPA AT KCRW AT ABOUT 21Z...AND REACHING POINTS EASTWARD BEFORE 00Z. WE ARE SEEING POPCORN CONVECTION FIRE ALONG FRONT...AND WE EXPECT LINE TO BECOME BETTER ORGANIZED AS THE AFTERNOON PROGRESSES. STRONG WIND GUSTS AND BRIEF IFR CONDITIONS ARE POSSIBLE WITH ANY THUNDERSTORM TODAY...WITH BEST CHANCES AT KCKB AND KEKN. THE PRECIPITATION WILL MOVE OUT OF THE AREA TONIGHT...BUT MVFR STRATOCU IS LIKELY TO LINGER...ESPECIALLY IN THE MOUNTAINS. STRONG SFC GRADIENTS WILL KEEP S TO SW SFC WINDS GUSTING TO AROUND 30 KTS AT TIMES TODAY...SHIFTING TO W TO SW WITH FROPA. WINDS WILL PERSIST INTO THIS EVENING...BEFORE GRADUALLY DIMINISHING OVERNIGHT TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z TUESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF MVFR STRATOCU WILL VARY. TIMING OF BEGINNING/END OF PRECIPITATION MAY VARY. BRIEF IFR POSSIBLE IN A THUNDERSTORM TODAY...BUT SHOULD NOT LAST LONG. 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 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H M M M HTS CONSISTENCY H H H H H H H H H M H H BKW CONSISTENCY H H H H M M H H H H H M EKN CONSISTENCY H H M M M M M H H H H M PKB CONSISTENCY H H H H H H H H H M M H CKB CONSISTENCY H H M M M H H H H H H M AFTER 18Z TUESDAY... NO WIDESPREAD IFR CONDITIONS EXPECTED AT THIS TIME. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KMC/KTB/ARJ NEAR TERM...KMC SHORT TERM...ARJ LONG TERM...KTB AVIATION...KMC

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