Area Forecast Discussion
Issued by NWS Charleston, WV

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493 FXUS61 KRLX 230808 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 308 AM EST Tue Jan 23 2018 .SYNOPSIS... Low pressure system exits northeast, but remains unsettled through Wednesday. Warmer to end the week. && .NEAR TERM /THROUGH TONIGHT/... As of 250 AM Tuesday... Line of showers weakening as it passes the I79 corridor this morning. Still have lingering showers behind this line, and the low level cold air advection lagging behind the cold front a bit, but will see slowly falling temperatures through the day. The broad upper level cyclone has pulled in dry air that will provide breaks in the clouds for the first part of the day, but the low level moisture returns and timed this with the higher RH values in the 925mb layer and the continuing cold air advection. This will last through tonight, and ramp the sky cover grids to overcast after 00Z Wednesday. That low level moisture should end up deep enough to warrant light isolated to scattered snow showers, most persistent in the mountains. Amounts in the near term will be light, with the only amounts over an inch in the highest ridges. Winds will be on the increase over the next several hours in descending air in the cold advection process. Will be transferring momentum down to the surface from around 800mb, but should stay well below advisory criteria. Highest elevations will receive the highest gusts. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 240 PM Monday... The dry slot behind the front fills in with low-level moisture as the upper low rotates through the area Tuesday Night. As a result of this and the passage of the upper level trough, there is an enhanced potential for accumulating snowfall in the northern lowlands and especially into the upslope areas of the mountains. New snowfall Tuesday night into Wednesday morning will amount to a dusting in the lowlands and around 2-3" in the mountain zones according to latest guidance. Gusty winds in the teens (lowlands) and up to the low 40`s mph will again be possible as the base of the trough moves through. A break in the action is forecast Wednesday with a weak ridge breaking otherwise troughing flow, however another upper level short wave is quick to follow that will again enhance precipitation potential. Any afternoon showers would be rain or a mix in the lowlands with light snow accumulations possible in the mountains late Wednesday through Thursday morning before drying out entirely. High pressure builds from the southwest, drying the region out and introducing warm air advection. Highs Thursday according to a model blend will reach into the 40`s in the lowlands and to around 30 in the higher elevations. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 PM Monday... Upper-level ridging increases and surface high pressure slides across the southern CONUS to round out the work week introducing warm air advection. Lowland temperatures Friday and Saturday will flirt with 60 F under mostly sunny skies (Friday) and continued WAA (Saturday) ahead of the next trough/surface low combination. At this time - a large amount of timing and depth uncertainty exists, so have kept the blend of operational guidance regarding PoP as well as temperatures. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... As of 1245 AM Tuesday... Line of showers with isolated embedded thunder now crossing the Ohio River and pushing slowly to the east, while individual cells are moving more rapidly to the north northeast. The history of this line and the cells within it are very brief IFR visibilities in rain and winds generally to 35kts in gusts. The timing of these and their arrival are still challenging, even in the very near term of the aviation forecast, so some amendments may be necessary. Behind the line and cold frontal passage, winds veer to the west southwest with gusts in the 25-35kt range. Ceilings will come down into prevailing MVFR between 1500-2700ft. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Frontal timing and restrictions 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 TUE 01/23/18 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 M L L L HTS CONSISTENCY H H H H H H H M H L M L BKW CONSISTENCY H H H M H H H H H M M M EKN CONSISTENCY H H L M H H H H H M M M PKB CONSISTENCY H H H H H H H H M L L L CKB CONSISTENCY H H M H H H H H H M M M AFTER 06Z WEDNESDAY... No widespread IFR expected. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/MC NEAR TERM...26 SHORT TERM...MC LONG TERM...MC AVIATION...26

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