Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 240229 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 929 PM EST Tue Jan 23 2018 .SYNOPSIS... Low pressure system exits northeast, but remains unsettled through Wednesday. Warmer to end the week. Cold front next weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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As of 620 PM Tuesday... Updating the forecast to raise sky cover overnight. Will also adjust temperatures a bit warmer for the next several hours based on current trends. As of 620 PM Tuesday... Updated the pops to better handle when the atmosphere will go auto convective with the cold air advection and hence start the snow in earnest. As of 205 PM Tuesday... Lull in the precipitation this afternoon, however, low clouds are gradually sneaking their way back into the CWA, with CAA and upper trough influence across the area. Gusty west/northwesterly wind continuing across the area this afternoon, will decrease somewhat overnight, but overall remain gusty for much of the period. With increase in moisture depth overnight, and a couple of shortwaves during the period, one late tonight/early Wednesday, and another one on Wednesday, expecting periods of light snow showers. Little to no accumulation expected across the lowlands, with light accumulations across the higher terrain. Although QPF will be light, high snow to liquid water ratios will allow for a few inches across the higher terrain counties. Possible that on Wednesday, area of -shsn activity may need to be increased in coverage and duration, but will allow future shifts to reevaluate this based on trends.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... As of 230 PM Tuesday... Any brief lull in showers during the day on Wednesday will fill in Wednesday night with the passage of another shortwave evident on all long-range models. Renewed CAA and some low-level flow off the Great Lakes will again generate snow showers, primarily across the WV mountains and perhaps into the northern WV lowlands immediately adjacent to the mountains. Many models are indicating more widespread snow shower activity, however CAA won`t be as strong as our normal post- frontal scenarios so have opted to dial back PoPs some, similar to previous forecasts, and defer to future forecasts when hi- res moisture data becomes available as it is more of a limiting factor. Accumulations through Thursday morning will be on the order of 2-3" in the mountains. High pressure builds to the southwest and slides from west to east, turning surface and low-level flow westerly, effectively cutting off any snow showers. Drying and warming will prevail through the end of the short term. Clouds from the southwest will start to stream in early Saturday morning ahead of the next system. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 250 PM Tuesday... Long-range models continue to struggle to grapple with the next system, with differences existing from the top-down. This model run, the GFS (still) tends toward a faster solution, the Canadian toward a slightly slower/deeper solution, and the ECMWF toward somewhere in the middle. Either way, there is consistency in widespread, overriding precipitation setting up over the lower Mississippi through the Ohio River Valley Friday night into Saturday, shifting westward through the weekend with the passage of a long-wave trough in the upper levels. Widespread rain showers are most likely late Saturday into Sunday... model differences return for the exit of precipitation. Again, the GFS is quite progressive with a digging trough making for a hasty exit of rain by mid-day Sunday and enough northwesterly flow behind to generate decent CAA/upslope showers. Meanwhile the ECMWF is slightly slower with less favorable low-level flow for showers on the backside of the system until the mid-level trough swings past Monday evening. A stronger, digging troughing would equate to a greater likelihood of widespread snow showers with the arrival of stronger CAA on the backside of the trough and cooler temperatures to start the work week. Opted to stick close to a blend of operational models Sunday through the end of the period given large model differences. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
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As of 625 PM Tuesday... Colder air will gradually filter into the area overnight, allowing for ceilings to gradually lower into the MVFR category. The atmosphere will become auto convective later tonight, allowing for some light snow, IFR at times. The best restrictions should be in the WV mountains, with some restrictions west of the mountains as well. Snow showers should tapper off Wednesday morning, but ceilings should remain MVFR for much of the area. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Timing and location of restrictions in snow could vary. 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 WED UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H M L H H H H M M M HTS CONSISTENCY H H M L M M M H H M L M BKW CONSISTENCY H H M M H M L L L L L L EKN CONSISTENCY H M L L L M L L L L L L PKB CONSISTENCY L H H H L M H H H M H L CKB CONSISTENCY H H M L L L L L H L H L AFTER 00Z THURSDAY... IFR snow possible in mountain terminals Wednesday night.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MZ/26 NEAR TERM...RPY/SL SHORT TERM...MC LONG TERM...MC AVIATION...RPY

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