Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 170815 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 315 AM EST Sun Dec 17 2017 .SYNOPSIS...
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Weak system brings spotty light precipitation today and tonight. Cold fronts cross Tuesday and again late week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 315 AM Sunday... Dampening wave coming out of the central plains this morning flattens almost completely, as it scoots quickly across the area today. The system was drawing low level moisture northward through the lower Mississippi Valley early this morning, and will then draw it eastward across the Tennessee and Ohio valleys today, and into the forecast area tonight. Very dry low and mid level air initially, and then upper level warming and drying reducing crystal growth later, spell very light precipitation that has difficulty reaching the ground initially, and then tends toward drizzle later on. Model soundings and guidance grids show surface temperatures near freezing in the northern mountains tonight, with an isothermal layer near freezing all the way through h7, as the cloud top lowers to h85 overnight. Freezing drizzle, very light freezing rain and / or sleet will be spotty, and barely if at all measure, even with upslope effects applied to a NAM and WRF QPF blend. A blend of MAV, MET, NAM and short term consensus was employed for temperatures, which flat line overnight after a modest evening drop, and then rise a bit in the mountains toward dawn Monday.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 250 PM Saturday... Dampening s/w trof quickly exits to the east Sunday evening. However, an abundance of low level moisture will linger along with some weak isentropic lift in WAA. This was handled with light rain and drizzle in the wx grids. There is some concern for perhaps some freezing drizzle or light freezing rain in the higher elevations, however confidence is not particularly high at this point for any mention in the HWO. All of this will try to linger for the first half of Monday along and north of the I64 corridor as WAA strengthens to our southwest. This may setup a significant temp gradient across the area with low stratus/drizzle across the north and some sunshine across extreme southern counties. I have undercut guidance for highs Monday quite a bit across the north as a result. The WAA eventually wins out by Monday evening. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 255 PM Saturday... A southern system will scoot by mainly to the south Wednesday and Thursday, though enough of a spread for some low pops across the mountains. Attention then turns to the weekend where there remains considerable spread on the synoptic pattern evolution across the eastern CONUS, as a battle looms between building warmth across the southern states and advancing cold air from Canada. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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As of 1255 AM Sunday... A weakening upper level wave will streak quickly across the area Sunday, bringing some light rain. However, the low levels are so dry, and the system will be moving so fast, that much of the rain will not reach the ground at first, and the rain does does is not likely to cause aviation restrictions. The system pulls east of the area Sunday night, ending the chance for rain, except in and near the mountains, where there may be MVFR stratocu. Otherwise, with so little rainfall expected, the chance for low cloud and fog forming Sunday night is low. Surface flow will be light south to southwest, beneath mainly light southwest flow aloft. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Formation of MVFR stratocu Sunday night may vary. Fog may start to form late Sunday night, especially if it rains more than expected. 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 SUN 12/17/17 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 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 M M BKW CONSISTENCY H H H H H H H H H M M M EKN CONSISTENCY H H H H H H H H H M M M 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 MONDAY... IFR in light rain and stratus at times overnight Sunday night through Monday night.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM NEAR TERM...TRM SHORT TERM...30 LONG TERM...30 AVIATION...TRM

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