Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 220633 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 233 AM EDT Tue Aug 22 2017 .SYNOPSIS... High pressure continues into Tuesday. Strong cold front late Tuesday into Tuesday night. Cooler and drier high pressure into the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 PM Monday... Made some minor tweaks to temps and dewpoints this evening, but no other changes made with forecast on track. As of 210 PM Monday... Mainly dry except in the north where a few isolated showers are possible this afternoon and evening. High pressure lingers into Tuesday, but then a well defined system translates through Tuesday evening. All indications suggest that there could be some severe weather with this frontal system though believe it will be north of the I-64 corridor. Ample moisture, upper and low level forcing, and wind shear all provide a favorable atmosphere for storm development and maintenance. Veering wind profiles also suggest some potential for rotating storms. Timing of the system, with the front moving through in the late afternoon, is just about right for maximum realization of CAPE. PW`s are also quite high in the 2.5" arena, so heavy downpours will also accompany these storms. Luckily they should have enough forward propagation that only local water issues may result. For now, gusty outflow from cells looks like the largest threat with damaging winds possible. The tornado and flash flooding threats are fairly low, but non-zero. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... As of 220 AM Tuesday... The post frontal environment will dry out quickly in northwest flow with broad scale surface high pressure building into the Ohio Valley. Some low level moisture advects back into the area in wrap around moisture, which would suggest sprinkles to isolated shower chances over the far northern CWA. However, leaving this out for now, and should be firmly entrenched north in the PBZ area. Temperatures give a slight hint to the twilight of summer with lowland 70s and dewpoints in the 50s for the short term. && .LONG TERM /SATURDAY THROUGH MONDAY/... As of 220 AM Tuesday... Outside of some isolated mountain showers, the extended is dry on the front end, with high pressure centered over eastern Canada controlling our forecast area. An upper level low will dig into the upper Mississippi Valley, meander eastward as it becomes cut off, and slow advects chances for showers into the western zones. As mentioned in past discussions, the dominant ridge/trough pattern across the CONUS from west to east will remain dominant. Expecting a slight increase in temperatures from the short term. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... 06Z Tuesday thru 06Z Wednesday... As of 215 AM Tuesday... Strong cold front moves across the area late this afternoon and tonight, well preceded by a line of strong to severe thunderstorms. Thru 13Z... Cirrus on the increase early morning. This, and some flow should keep dense fog in only the most protected valleys. Did include LIFR at EKN in the deeper valley and with the thinest clouds til 13Z. Elsewhere, marginal MVFR valley fog at best possible. Today after 13Z... Out ahead of aforementioned line of thunderstorms, VFR with generally cirrus this morning, then SCT-BKN clouds 4000-6000 feet AGL after 17Z with isolated thunderstorms mainly west. Light south winds becoming southwest 10 to 20 KTS and gusty by late morning. Best estimate. Line of TSTMS expected to arrive at Ohio River 20Z-22Z and CKB-CRW line 23Z-01Z and into the mountains 01Z- 03Z. Conditions varying greatly within this line, lowering to IFR at times, so will put PROB30 in TAFS at this distant time frame, with strong gusty west winds and hail possible. Behind this line, outside of mountains generally VFR ceilings 3500-5000 feet with scattered showers for 1-3 hours, then clouds decreasing in the west. In the mountains, MVFR ceilings and showers will linger thru rest of period. Winds becoming west 5 to 8 KTS behind the front which will reach the mountains around 06Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Main line of storms with cold front later today could arrive a bit earlier than 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. DATE TUE 08/22/17 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY M L L L L L L M H H H M PKB CONSISTENCY H H H H M M M H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 06Z WEDNESDAY... IFR possible in low stratus and showers/fog into early Wednesday for mountains. River valley fog possible each morning through the weekend. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JMV/26 NEAR TERM...JW/MZ SHORT TERM...26 LONG TERM...26 AVIATION...JMV

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