Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 240820 AAA AFDRLX Area Forecast Discussion...UPDATED National Weather Service Charleston WV 420 AM EDT Mon Apr 24 2017 .SYNOPSIS... Low pressure meanders slowly through the carolinas through Tuesday, and then fills as it moves up the middle Atlantic seaboard through Wednesday night. Next front Thursday night. && .NEAR TERM /THROUGH TONIGHT/...
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As of 420 AM Monday... A stacked low pressure system south of the area will continue to chug across the carolinas toward the coast this period. The left branch of the warm conveyor belt was only producing spotty light rain out of a mid cloud deck across the middle Ohio Valley. The right branch was bringing about a steadier rain in the central Appalachians, but rainfall rates were a quarter of an inch an hour or less. Guidance continues these trends today and tonight, as the system slowly pushes east. Therefore expect flooding to gradually abate this morning in the flash flood watch area, and was not expecting new problems farther north in the central Appalachians, where rainfall amounts Sunday were far less than in the watch area. Nonetheless, have introduced or increased chance PoPs farther northwest into the middle Ohio Valley on the areas of light rain in the left branch of the warm conveyor belt today. Meanwhile, rain continues in the central Appalachians today under the right branch of the warm conveyor belt. The rain will be mainly on the ridges and southeast slopes given low level southeast flow. Saw no compelling reason for much increase in intensity there given the system is at its closest approach and near peak intensity. Some intensification is progged later today, but its effects will occur farther east by then. As the system shifts east tonight, the chance for rain will come to an end over the middle Ohio overnight, while rainfall diminishes over the central Appalachians with that area under the left branch of the warm conveyor belt, the right branch having shifted east. Lack of CAPE surface based or elevated takes convection and its complicating effects out of the picture. Low clouds should remained banked up along the southeast slopes of the central Appalachians through tonight. Fog farther west overnight tonight will depend upon the boundary level winds, which look to be marginal, although pockets of dense fog seem likely under lighter flow in an inverted trough just west of the mountains in WV. A blend of near term guidance and previous forecast appeared to have a good handle on temperatures and dew points lowest along the southeastern slopes of the mountains.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 315 AM Monday... Overall drier weather expected in the short term period. Low pressure will continue to move east and north along the Atlantic Coast, with light rain shower activity continuing along far eastern zones. No additional flooding concerns are expected. A brief warming and drying trend is expected on Wednesday, as high pressure and upper ridging builds into the region, along with increasing southerly flow out ahead of an approaching cold front. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 315 AM Monday... Cold front will spread showers and thunderstorms back into the region by Thursday. At this point, no widespread severe is expected due to timing, and overall lack of significant dynamics. There will however be the possibility of brief heavy downpours, as PW values rise to over 1.1 inches once again. Focus then shifts to a strengthening low pressure system across the Gulf region, that will lift a warm frontal boundary across the area this weekend, with showers and thunderstorms returning. Heavy downpours will be possible again, as strong southerly flow aids in high moisture transport to the region. Cold frontal boundary with the system is progged to arrive on Monday. && .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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As of 215 AM Monday... The area will be on the northwest fringes of a low pressure system moving slowly through the carolinas this period. All sites were VFR at the start of the forecast, and PKB and CKB will remain VFR. However, as the rain shield pushes northward overnight and Monday, sites farther south and east, HTS, CRW, EKN and BKW, will have MVFR conditions at times in ceilings and, to a lesser extent, visibilities. Conditions will improve to VFR late Monday or Monday night, except at BKW, which carries the highest uncertainty, as it will be on the edge of MVFR to IFR ceilings down the southeast side of the ridge the entire time. Surface flow will be light east to northeast, except east to southeast in the mountains, and around 10 kts with some gusts to around 20 kts at BKW. Light east to southeast flow aloft overnight will become light to moderate southeast on Monday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z TUESDAY... FORECAST CONFIDENCE: Low to Medium. ALTERNATE SCENARIOS: Timing of rain and category changes may vary. BKW will be near the edge of MVFR to IFR ceilings much of the time, even as sites northwest of there have MVFR ceilings at times. 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 04/24/17 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY M L M L L M M M M L L L HTS CONSISTENCY L L L L L L L L M L L L BKW CONSISTENCY M M H M M M M M M L L L EKN CONSISTENCY H H H H M H H H H L L L PKB CONSISTENCY H H H H H H H H H M M M CKB CONSISTENCY H H H H H H H H H M M M AFTER 06Z TUESDAY... IFR may linger across the southeast slopes of the mountains into Tuesday morning.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch until 2 PM EDT this afternoon for WVZ033-034. OH...None. KY...None. VA...Flash Flood Watch until 2 PM EDT this afternoon for VAZ003-004. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM

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