241 FXUS61 KRLX 290701 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 301 AM EDT Sun Sep 29 2019 .SYNOPSIS... Unseasonably warm through mid-week as the ridge aloft builds again. Strong cold front arrives Thursday with much cooler conditions for the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 230 AM Sunday... Surface observation field reveals a quasi-stationary frontal boundary extending from just south of Parkersburg to south of Cumberland along with a decaying outflow boundary stalling just north of Charleston. This may provide a modicum of relief for our northern SE Ohio counties with stratocu north of the front limiting daytime highs in the mid 80s while the remainder of our lower elevation zones languish in the lower 90s. The front and perhaps less so the OFB combined with a weak mid- level impulse rotating around the northern periphery of the building upper should provide just enough surface moisture convergence and cooling/moistening of a weak subsidence inversion to spark scattered showers and thunderstorms this afternoon. Given timing of the wave, think these will largely be limited to the northeastern quarter of the forecast area with inversions just too strong to overcome without the aid of surface heating further west. MLCAPE in this area will be in the 1000-1500J/kg range with deep layer shear generally under 25KTs. With the proximity of the boundary can't completely rule out a storm or two that latches on showing at least some organization in Randolph or Pocahontas County this afternoon and with a dry layer between H800 and H600 could see a brief threat of some marginal hail if this were to materialize. Any storms that do manage to get going will quickly wane with loss of surface heating/passage of the mid-level wave. Another weak wave edges by the northern fringes of the forecast area Monday morning as the upper level ridge begins to move overhead. This may spark a few additional morning showers, but subsidence associated with the ridge will be increasingly hard to overcome without forced ascent against terrain. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... As of 255 AM Sunday... The center of the upper ridge located over the northern Gulf Coast region translates to ridge riding waves and instability and the need for low end POPs for portions of the CWA. The forecast is definitely conservative in this case for Monday and Tuesday, with no POPs for the latter, which may be a tad too conservative. The ridge builds in strength once again and will drift northwestward into the mid Mississippi and lower Ohio Valleys, shunting any potential upper level waves aloft well to the north and returning the area to the unseasonably hot and dry airmass that has set up shop for some time now. Lowland temperatures back in the lower to mid 90s through mid week, and in this airmass with dewpoints in the mid 60s, it gets a touch more uncomfortable than previous days. Heat indices will be in the mid 90s, shy of advisory criteria as we enter October. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... As of 255 AM Sunday... Finally get an airmass changing frontal system as the upper ridge flattens out and degrades and the flow turns more zonal. While the need for rain does not change, models are pessimistic on the amount and coverage from this system as of this issuance. However, the temperatures should drop about 15-20 degrees into the weekend, finally pushing readings back to their near normal values for early October. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... As of 130 AM Sunday... Difficult fog forecast overnight with a smattering of mid-level cloudiness slowing radiational cooling during the early overnight. Highest confidence in IFR fog impacts at PKB, CKB, and EKN in the vicinity of a stalled frontal boundary as well as some decent localized rainfall that fell earlier Saturday. A little less confidence in fog development at HTS and CRW with more substantial mid-level cloud cover overhead at the current time. This should clear out over the next couple hours, but may delay cooling to saturation long enough to limit fog impacts to an hour or two near daybreak. Weak mid-level wave crossing the stalled frontal boundary this afternoon will spark showers and thunderstorms with the most likely terminals to see impacts EKN and CKB. Have just gone VCTS/VCSH for now given likely spotty nature of any convection that develops. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY... FORECAST CONFIDENCE: High except low in fog coverage this morning. ALTERNATE SCENARIOS: Fog coverage and intensity will vary significantly over short distances with varying cloud cover this morning. CKB/EKN could see additional brief MVFR/IFR impacts under localized heavy precipitation cores this afternoon. 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 SUN 09/29/19 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 L L L L L L L H H H H HTS CONSISTENCY H H M M L L L H H H H H BKW CONSISTENCY H H L L L L L H H H H H EKN CONSISTENCY L L L L L L L L H H H H PKB CONSISTENCY H M L L L L M M L L L L CKB CONSISTENCY H H L M M M M L L L H H AFTER 06Z MONDAY... IFR or worse river valley fog possible Monday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/JP NEAR TERM...JP SHORT TERM...26 LONG TERM...26 AVIATION...JP