Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231844 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 244 PM EDT Tue May 23 2017 .SYNOPSIS...
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Upper level low digs into the Tennessee Valley and brings chances of showers tonight through Friday.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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As of 235 PM Tuesday... Digging upper level low over the Midwest is kicking out embedded waves in the cyclonic flow out ahead of it, the first of which arriving is responsible for an expanding precipitation shield now pushing across the Tug Fork Valley. So the coverage of rain will be on the increase through this evening, especially over the Ohio Valley as the waves aloft push into the region. Really wanted to take the thunder out, but will allow the slight chance of thunder through the evening even pushing the procedure with higher CAPE criteria to generate the areas of thunder. The upper closed low will continue to dig into the Tennessee, while continuing to eject energy into the CWA. Should get a lull later tonight, but ramp the POPs up fairly sharply heading into Wednesday. The old day 2 rainfall forecasts from WPC puts the mountains in a marginal risk for excessive tomorrow. For the lowland areas, this should equate to a half inch to three quarter inch even through 00Z Thursday, and possibly double that for the mountains. Not expecting water issues as of this issuance, and no headlines in place. Upper level low to keep the temperatures in check through the near term, with lowland 50s tonight and around 70 to the lower 70s Wednesday.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 245 AM Tuesday... Models have remained fairly consistent with deep upper trough/low impacting our region Wednesday into Thursday. GEFS indicating an anomalous jet max for this time of year at 4 to 5 standard deviations above normal. We will be in a good spot in the left front quad of this jet max as it pushes north around the trough. Current blend of forecast guidance is spitting out about a 1 inch bullseye of QPF over Central through Eastern West Virginia, with Euro a bit further west than the GFS at this time. PWATs aren`t overly impressive and low CAPE values as well based on forecast soundings, so thunderstorm and flood threat will be minimal . However, with upper trough swinging in and cold temps aloft, I do believe there will be some embedded thunderstorms within a wide band of showers Wednesday afternoon through early Thursday morning. The upper level low will remain over the area on Thursday and more showers and isolated thunderstorms are possible. Temps will be quite a bit cooler as well, with highs only mid 60s in the Lowlands and 50s in the mountains. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 AM Tuesday... Upper trough kicks to our east and a zonal pattern is left in its wake. Guidance in fairly decent agreement with a brief dry period on Friday as weak ridge pushes in. However, the weekend is looking quite unsettled at this time. Strong warm air and moisture advection with H850 showing southwesterly return flow from the Gulf of Mexico. Should definitely have the instability in place this weekend, but timing of short waves moving through the flow will determine severe weather potential. Confidence remains quite low at this time due to some differences within the guidance, so have stuck with a blend of ensemble and operational guidance for this period and have mentioned the chance for thunder in the forecast simply because of instability that is likely to be in place. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/...
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As of 125 PM Tuesday... Have some wholesale changes in effect for the afternoon issuance of the TAFs, primarily dealing with earlier arrival and longer duration of rain across the region thanks to an upper level wave moving in from the southwest. Expect coverage to increase from development of showers as much as showers moving in. Biggest concern off the top is duration of the rain that can often times lead to ceilings collapsing down to IFR, but have held this off in the forecast until after 00Z and later, with the expectation of convective rain keeping to lowest levels churned enough. Have quite a bit of IFR in the forecast however once this upper level wave exits, which could give the lesser seen IFR ceilings and visibilities as winds approach calm. The timing is tough as well. Higher chances for showers return after 10Z Wednesday, but southeast wind should help lift ceilings after sunrise. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: Low to medium. High confidence on rain overall, but timing and subsequent conditions when periods of rain end are tricky. ALTERNATE SCENARIOS: Timing of rain could vary. May need to be more aggressive with IFR or LIFR 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 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 M L L L HTS CONSISTENCY H H H H H H H H M L L L BKW CONSISTENCY M M M M M M M M L L L L EKN CONSISTENCY H H H H H M M M L L L L PKB CONSISTENCY H H H H H H H H M L L L CKB CONSISTENCY H H H H H H H H L L L L AFTER 18Z WEDNESDAY... Upper level low keeps IFR chances in play through Thursday night.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MPK/26 NEAR TERM...26 SHORT TERM...MPK LONG TERM...MPK AVIATION...26

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