Area Forecast Discussion
Issued by NWS Charleston, WV

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141 FXUS61 KRLX 291459 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1059 AM EDT THU SEP 29 2016 .SYNOPSIS... A large upper level low will bring wet weather today through Friday. It pulls away in time to bring dry weather for the weekend. High pressure continues the dry weather early next week. && .NEAR TERM /THROUGH TONIGHT/...
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1050 am update...Added a higher chance of thunderstorms to the forecast through today. With cold temps aloft and low freezing levels any storms that reach about 15K feet should start producing lightning. Also, I did not put any hail in the forecast at this time, but some isolated stronger storms could produce small hail. 850 am update...Went ahead and boosted PoP across the CWA today with the upper low producing widespread showers. Current thinking is that Flash Flood threat is fairly low today...however we will have to monitor for training today with unidirectional flow and diffluence aloft . It is still possible that a flash flood watch may be needed at some point...but will hold off at this time due to dry conditions and uncertainty on where the heaviest precipitation will set up. Previous Discussion... As of 420 AM Thursday... Unsettled and cool weather for the near term period...as surface cold/occluded front pushes east through the region today...and as upper low...which will slowly dig south into Kentucky today...and associated vort maxes...help to trigger showers and thunderstorms...particularly this afternoon. There is the possibility that a few storms could be on the strong side...particularly across the eastern 2/3 of the CWA. Any breaks that are able to develop in the cloud cover today will help to destabilize the environment...and this combined with strong shear...could lead to organized/strong convection...with damaging winds a primary threat. Small hail can also not be ruled completely out...or the possibility of an isolated tornado. SPC has placed the majority of the CWA in a marginal risk...with southern/eastern WV zones in a 2 percent for tornadoes. Will highlight in the HWO. In addition to the severe threat...there will be heavy downpours with any storms...but with the overall dry conditions and storm movement...not concerned about issuing any water headlines. Based on water vapor imagery...and model consensus...heavier axis of moisture/precip should stay just to the east of the CWA...where stronger low level winds will aid in higher moisture transport off the Atlantic.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 420 AM Thursday... Large upper level low over the lower Ohio Valley at the start of the period swirls about there into Friday night, before moving northward through Indiana Saturday and Saturday night, ending up somewhere over lower Michigan by Sunday morning. Showers are most likely across northeast portions of the area Friday, as a ripple moves up the east side of the upper level low, roughly along the surface occlusion. A thunderstorm is also possible in that area, especially right along the occlusion itself, where a narrow axis of mainly elevated instability will exist. The occlusion will have thinned out this axis compared with today. Coverage of showers decreases in the aging occlusion Friday night through Saturday, with much of the area getting into a widening dry slot. The upper level low drifts eastward through the eastern Great Lakes Sunday and Sunday night, and the dry slot opens up as drier air arrives from the west. Dense fog is likely Sunday and Monday mornings on account of very light flow, and the wet weather today into Friday night. No major changes were needed to temperatures, which are close to guidance blends by day and bias corrected guidance by night, and not far from normal overall. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 230 PM Wednesday... The pesky upper low will be out of our hair Sunday. In its wake the region will experience rising heights and warming conditions, potentially to well above normal once again next week. && .AVIATION /15Z THURSDAY THROUGH MONDAY/...
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As of 630 AM Thursday... Upper level low will continue to rotate across the area during the period...with areas of showers...and thunderstorms...particularly after 16-18Z. Expect brief gusty winds...heavy downpours...and MVFR/IFR conditions at times...particularly in vicinity of showers/storms. Bulk of convection will die off after 00Z...however...showers with restrictions...and areas of MVFR/IFR cigs and vsbys will continue to linger for the remainder of the period. Isold LIFR possible in low cigs and fog after 06Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Coverage and timing of convection this afternoon...and resultant MVFR/IFR restrictions may vary from forecast. Isold LIFR in question tonight. 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 15 16 17 18 19 20 21 22 23 00 01 02 EDT 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 CRW CONSISTENCY H H H H L H H H M L L L HTS CONSISTENCY M M H H M L L L M L L L BKW CONSISTENCY M M M H H H H H H L L L EKN CONSISTENCY H H H H H H H H H H H L PKB CONSISTENCY M M M M M H M M M L L L CKB CONSISTENCY H H H H H H H H H H L L AFTER 12Z FRIDAY... Areas of ifr possible in showers and thunderstorms through Saturday, and in dense fog Sunday and Monday mornings.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM/MPK SHORT TERM...SL LONG TERM...30 AVIATION...SL

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