Area Forecast Discussion
Issued by NWS Charleston, WV

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957 FXUS61 KRLX 201908 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 308 PM EDT Mon Mar 20 2017 .SYNOPSIS...
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Cold front with showers and some thunderstorms crosses tonight. Upper disturbance passes Tuesday night. High pressure Wednesday night and Thursday. Warm front Friday. Cold front over the weekend.
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&& .NEAR TERM /THROUGH TUESDAY/...
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As of 305 PM Monday... Radar showing a nice MCV translating into WV and passing north of CRW as of 1845Z. This feature, along with lingering showers, are the remnants of the early day MCS that continues to weaken as it pushes south. Because of the associated cloud cover, have not seen temps rising as quickly, so bumped highs down a couple of degrees, mainly across the lowlands. Visible satellite does show a break in clouds across southeastern OH that will translate southeastward into our forecast area over the next few hours. Behind this clearing, a developing MCS continues to intensify invof a frontal boundary and upper shortwave trof. Thermodynamically, the atmosphere near/ahead of this complex remains marginal. Continued WAA and increased solar insolation will contribute to some destabilization, but NAM4KM and RAP output only show around 500-700 J/kg of MUCAPE. However, deep layer shear aoa 40 kts will be sufficient for thunder beginning later this afternoon. Lower freezing levels will permit hail growth in stronger updrafts, although severe hail and/or wind are not expected. Expect SHRA and TSRA to increase from the northwest after 20-21Z, eventually overspreading the area after 00Z. The cold front will pass overnight into Tuesday morning with lingering showers along and south of the OH River through Tuesday. Some thunder is possible in extreme southern counties Tuesday afternoon as higher instability noses in from the west. Used a blend of guidance for mass fields with HRRR output preferred for PoP timing and coverage. As of 1130 AM Monday... Decaying MCS continues sagging south and east, affecting areas mainly along/north of the OH River attm. Radar trends over the past few hours show slower than expected weakening with the precip shield finally starting to erode along its northern and eastern periphery. Disagreement persists among hi- res models with the NAM trying to dissipate this feature too quickly while the HRRR weakens then dissipates the remnants in the southern Coal Fields after 20Z. Siding more with the HRRR for timing and areal coverage of precipitation through this afternoon. Attention then turns to a cold front and upper wave, which will approach from the north later in the afternoon. Isolated areas of increasing reflectivity and cloud flashes across the KLOT forecast area signal new convective development associated with this feature, which will approach our northern counties after 21Z. Data from the 12Z KILN RAOB show a morning freezing level around 11 kft with hourly RAP analysis coming up just shy of that. Deep layer shear was observed around 35 kts and will increase slightly through the day in response to the approaching front/wave. Lower freezing levels will aid in small hail potential if more vigorous updrafts materialize with afternoon and evening convection. Will further address frontal thunder chances with afternoon update. Otherwise, minor tweaks to temp grids based on morning obs data. Used a general blend of model guidance heavily weighted toward the HRRR and previous forecast, which remains largely on track.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 420 AM Monday... Tuesday morning finds a cold front at least half the way through the forecast area, and an upper level wave moving off to the east. The cold front slips southward, through the remainder of the area, by Tuesday afternoon, taking any showers with it. Left a small chance for thunder in the extreme south midday Tuesday, just before the front moves through there. Models show a flat wave moving across the area Tuesday Night, bringing about a renewed chance for precipitation. Given the sloping baroclinic zone on the north side of the front south of the area, we are looking at mainly mid and upper level moisture and hence light precipitation. The colder air moving in behind the front may allow a transition from rain to snow from north to south overnight Tuesday night into Wednesday morning, with very light accumulations possible in the mountains. Cloud temperatures favoring crystal growth and dry air below the cloud base favor a transition of any precipitation to snow during this time. Strong high pressure featuring cold and very dry air dominates Wednesday afternoon through Thursday, as it passes north of the area. Temperatures close to central guidance including a very cold Thursday morning, about ten degrees below normal, for a hard freeze for any agricultural interests. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 420 AM Monday... Warm advection precipitation may scoot across northern portions of the forecast area Thursday night into Friday. The retreating cold air may hang on long enough for snow furthest east, across northeastern WV. The area breaks out into a warm sector Friday afternoon into Saturday. A cold front approaches later Saturday and is likely to cross later Saturday night or Sunday, ahead of which thunder is possible. Low pressure approaching from the west on Monday may lead to a continued or renewed chance for precipitation. Have lows occurring early Thursday night as warm advection develops overnight. Otherwise temperatures close to central guidance, which is a little below the MEX over the weekend. && .AVIATION /19Z MONDAY THROUGH SATURDAY/...
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As of 305 PM Monday... Decaying MCS continues pushing south through the forecast area this afternoon. Remnant showers will affect KBKW over the next couple of hours, with impacts limited to brief MVFR cigs. Another round of showers and some thunderstorms associated with a cold front will begin overspreading the area after 20-21Z, progressing from northwest to southeast across all terminals through the overnight. Kept TAFs slightly optimistic at KHTS/KCRW/KPKB by holding cigs right above IFR, although briefly lower cigs are possible. Likewise for vsby with borderline MVFR/IFR overnight in heavier showers. For mountain terminals, did introduce periods of IFR with brief LIFR possible after 08-09Z Tuesday. Lingering moisture will keep -SHRA and BKN to OVC cigs through much of the day Tuesday, with only small chances for improvement after 15-16Z. Expecting frontal boundary to cross slowly through the night with winds shifting to northwesterly behind the boundary. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z TUESDAY... FORECAST CONFIDENCE: Medium/High outside the mountains. Lower confidence with IFR/LIFR chances overnight and Tuesday morning. ALTERNATE SCENARIOS: Timing of any showers or isolated thunderstorms, and resultant MVFR or worse conditions may vary from forecast. 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 M M L HTS CONSISTENCY H H H H H H M M M M M L BKW CONSISTENCY H H H H H H H H H M M L EKN CONSISTENCY H H H H H H H H H H H L PKB CONSISTENCY H H H H H H M M M M M L CKB CONSISTENCY H H H H H H M M H H H M AFTER 18Z TUESDAY... IFR possible in low cigs and -shra Tuesday.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...SL/DTC NEAR TERM...DTC SHORT TERM...TRM LONG TERM...TRM AVIATION...DTC

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