Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
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418 FXUS61 KRLX 270835 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 435 AM EDT Fri Sep 27 2024 .SYNOPSIS... Remnants of Helene arrive this morning, spreading strong gusty winds and additional rainfall today. More rain chances over the weekend into early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 430 AM Friday... Key Points: * Flash Flood Watch in effect until 7 PM today for southwest VA, mountains of WV and the Tri-State Area. * High Wind Warning in effect until 7 PM today across the mountains of southwest VA and WV. * Wind Advisory in effect until 7 PM today for portions of the coalfields, foothills and mountains of WV, as well as portions of the the Tri-State Area. A frontal boundary spawning off from the north of Hurricane Helene is currently over the area. As a result, expecting showers and gusty winds to impact the area starting early this morning as Helene tracks north and west into the CONUS. The center of the remnants will pass to our west over Kentucky this afternoon/evening. Helene is weakening quite a bit since making landfall and it will be a quick moving system. Most of our impacts will be seen this morning into early afternoon. Some hold over into the evening is possible with any flooding that may arise. There is a moderate risk for excessive rainfall across portions of Dickenson and Buchanan counties in VA and a slight risk of excessive rainfall across the far southern coalfields and mountains of West Virginia. Models show the bulk of the rain falling between 6 AM and 3 PM today, with the highest amounts between 1.00" and 1.30" across our northeastern KY counties and southwest VA counties. Did continue and expand the flood watch accordingly to cover any areas of concern. The wind threat has been increased with latest short-range guidance, particularly across the higher ridges of the mountains. The potential is there with this fast moving storm as southeast flow becomes enhanced across the ridgetops above 2,500 feet. Used a HREF/HRRR blend which has gusts between 50 and 60 mph for much of the higher elevations this morning, with some locally higher gusts possible. Did upgrade or add counties to a high wind warning to cover this. Also expanded the wind advisory across portions of the lowlands. Did not go with any short-range bias for the lower elevations as the winds were way overdone across this area. There is a chance that the wind factor is less substantial than advertised if Helene continues to rapidly weaken as it traverses inland. Otherwise, fairly confident that criteria will be met across the higher elevations particularly in our southern mountain counties of WV and southwest VA. There is a marginal risk for severe weather concerning tornado risk. This outlook is clipping our VA counties and far eastern McDowell County up to eastern Fayette and southeast Pocahontas County. Some stronger cells on the northeastern side of this system do have the potential for rotation, but the highest risk remains to our east. Will start to see winds and some of the shower activity tapering off this afternoon into the evening as the remnants sit to our west. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 250 AM Friday... Key Points: * Rain chances will diminish for most on Saturday, but return area-wide on Sunday and Monday. Some areas of heavier rain could lead to localized water issues. Between the remnants of Helene briefly heading over towards the lower Ohio Valley and us getting some downsloping on SE`ly winds, much of the CWA could be rain-free to start the period on Saturday, and perhaps even into Saturday night. However, as the remnant low of Helene then treks back east across Kentucky on Sunday, moisture across the area will increase and our winds shift more S`ly, resulting in widespread rain spreading east across the CWA. There`s also the chance for some embedded thunderstorms and areas of heavier rain, so WPC does look to continue the Marginal excessive rainfall risk on Sunday for most of our counties excepting Ohio. We expect more area-wide rain on Monday, but the thunderstorm and heavy rain risk seems more contained to the mountains, which is matched by WPC limiting Monday`s marginal risk to the mountains and western upslope areas. There is some disagreement among the models on the speed at which the upper-level low/trough will shift east of the area, which would mark the time we expect a reduction in precip coverage across the lowlands. Some show it as early as late Monday night, but others hold off until Tuesday. Thus we maintain at least Chance POPs across the lowlands through Mon night. With the potential for some downsloping especially on Saturday, and perhaps some partly cloudy skies west of the mountains, we do have highs along the I-79 corridor getting to 80 or even into the low 80s, but 70s for most of the rest of the lowlands. With increased cloud cover and precip coverage, highs Sunday and Monday will be limited to 70s for the lowlands and southern mountains, and 60s for the central and northern mountains. && .LONG TERM /TUESDAY THROUGH THURSDAY/... As of 315 AM Friday... We won`t be done with the precip quite yet, as the departure of the Helene remnants and upper low will be quickly followed by another upper-level shortwave trough and surface cold front later Tuesday into Tuesday night. Thus, we maintain slight chance to chance POPs across the area on Tuesday, and for most of the are southeast of the Ohio River through Tuesday night. Depending on the timing of the front, the POPs on Tuesday night might actually be a bit undone by the NBM if you believe the ECMWF and CMC deterministic runs, but the 00z ensemble guidance for now seems to support the lower POPs depicted. Aside from a few stray mountain showers in upslope flow, much of the area will see clearing on Wednesday, with dry weather area-wide on Thursday. After Tuesday continues the trend of lower elevation highs in the mid to upper 70s and mountains getting into the 60s, highs on Wednesday are forecast to be 5 to 8 degrees cooler for most places. Temps recover on Thursday as winds shift S-SW`ly but skies likely remain mostly clear. May need to monitor for frost potential in the high valleys Wednesday night. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... As of 130 AM Friday... Most sites are reporting VFR currently except for BKW, where MVFR/IFR CIGs are prominent and will be through the period. MVFR and IFR could also be expected at HTS and possibly EKN through the period, but BKW will likely see the the worst conditions through the period. Mostly VFR could be expected elsewhere. Bands of precipitation associated with moisture from Hurricane Helene to our south will ripple across the area early this morning, becoming more widespread by and after ~12z. MVFR/IFR VIS likely within any showers/storms. Southeast winds will strengthen through the morning peaking between 12 and 18z. Sustained winds between 15-25kts for most, especially the mountains with gusts between 25 and 40kts. Higher gusts approaching 50kts are possible for elevations above 2,500 feet in elevation (i.e. BKW). Winds will gradually start lessening in the afternoon, but may increase overnight into Saturday morning, particularly across the southern portions of the forecast area. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing and extent of low CIGs, precipitation, and gusty winds could vary from 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 FRI 09/27/24 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY M M H H M M H H M M M M HTS CONSISTENCY M M M H H H L L M L L M BKW CONSISTENCY M M M M M M M H L M M M EKN CONSISTENCY M H H H M H H M H H H H PKB CONSISTENCY H M H H H M M M M M L H CKB CONSISTENCY H H H H H M M M M M M M AFTER 06Z SATURDAY... Brief, but repetitive periods of IFR conditions possible in showers and storms into the weekend. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flood Watch through this evening for WVZ005-033-034-515-516- 518-520-522>524. Wind Advisory until 8 PM EDT this evening for WVZ005-006-013- 024>026-517-519-521-524-525. High Wind Warning until 8 PM EDT this evening for WVZ033-034- 515-516-518-520-522-523-526. OH...Flood Watch through this evening for OHZ087. Wind Advisory until 8 PM EDT this evening for OHZ083-086-087. KY...Flood Watch through this evening for KYZ101>103-105. Wind Advisory until 8 PM EDT this evening for KYZ101>103-105. VA...Flood Watch through this evening for VAZ003-004. High Wind Warning until 8 PM EDT this evening for VAZ003-004. && $$ SYNOPSIS...FK/LTC NEAR TERM...LTC SHORT TERM...FK LONG TERM...FK AVIATION...LTC