Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 271834 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 234 PM EDT Sat May 27 2017 .SYNOPSIS...
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Rounds of convection are expected this holiday weekend, until a cold front crosses Sunday, followed by another Monday morning. Additional cold fronts cross Tuesday and Wednesday.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 230 PM Saturday... Cap is finally breaking over the northern tier of counties where the better clearing has taken place over the last couple of hours. Still looking at a high CAPE and moderate bulk shear environment, so expect the activity to continue on the upswing heading into the late afternoon and evening. So far, the pace has been more than manageable, but still have a few hours of heating left and we have already hit the convective temperature. Have both the hail and wind threat going forward. No changes to the SPC slight risk for us in terms of severe. Meanwhile, precipitable water values pushing 1.50in have warranted the flash flood watch in place over much of the southern portion of the CWA. Flash flood guidance values still high, so thresholds for additional rain down in these areas is low. Repetitive rounds of storms could easily become troublesome. Have tailored the POPs for a lull in the activity late this evening and early tonight, before the front swings back northward again as a warm front. Pre dawn convection expected to move north through the area, and back into the slight risk area for Sunday as the cold front passes again.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 515 AM Saturday... Additional convection Sunday and Sunday night will be dependent upon previous convection leaving behind a worked over environment. Several boundaries are likely to be in the area Sunday, including at least one outflow boundary somewhere across the south, and a more synoptically driven boundary to the north. There may also be a north to south oriented boundary crossing as a surface reflection of an upper level short wave trough. Model differences in moisture and instability on Sunday reflect the possible effects of a cool pool from previous convection. Models are in better agreement on most of the CAPE being elevated and thickest in the hail growth layer. This somewhat tempers the diurnal dependency of convection. Deep layer shear is forecast to be in the 40 to 50 kt range. All of this suggests showers and thunderstorms around from time to time Sunday through Sunday night, with repetitive downpours possible. Also, afternoon recovery would add surface based instability to the equation, resulting in very strong, heavy thunderstorms. Finally, to go along with these parameters, sigtor values are forecast to climb to 1 to 1.5 in an axis ahead of a cold front approaching from the west Sunday night. The flood watch goes until 12Z Monday when the cold front goes through, and the HWO also highlights the convective threat. Yet another cold front crosses late Tuesday. While weaker and with less available moisture than the weekend system, it will still be able to garner enough moisture and shear for thunderstorms. No deviations from central guidance temperatures but values will fluctuate with the convective complexes. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 515 AM Saturday... This period features a large upper level low over eastern Canada with long wave trough over the eastern United States. This spells a cool, more tranquil pattern once a reinforcing cold front crosses on Wednesday. PoPs increase again next weekend, as that trough lifts out, and allows another system to approach from the west or southwest. Central guidance temperatures reflect the slightly below normal pattern. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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As of 145 PM Saturday... Convection/storms will be around through the evening. The challenge, of course, is determining effects on individual terminals. With that said, attempted as best as possible with rapid update high res models to time POPs on terminals and reflect that in the TAFs, while trying to not overpopulate with VCTS/CB. Some TEMPOs used in this case to cover, but can see AMDs being needed as the storms evolve and move over the next several hours. Gusty winds and hail are possible. Expecting a lull during a portion of the overnight, with a warm front returning and bringing morning convection back into the fold. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Convection timing likely to vary as storms evolve. May need fog tonight in brief clearing. 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 M H H H H H H L HTS CONSISTENCY H H H H H H H H H H H L BKW CONSISTENCY H L L M M M M M M L M L EKN CONSISTENCY M H M H H H H M M L L L PKB CONSISTENCY H H H H H H H H H H L L CKB CONSISTENCY H M H M H H H H H H H M AFTER 18Z SUNDAY...
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch through Monday morning for WVZ005>008- 013>016-024>027-033-034-515>520. OH...None. KY...Flash Flood Watch through Monday morning for KYZ102-103-105. VA...Flash Flood Watch through Monday morning for VAZ003-004. && $$ SYNOPSIS...TRM/SL NEAR TERM...26 SHORT TERM...TRM LONG TERM...TRM AVIATION...26

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