132 FXUS61 KRLX 212355 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 655 PM EST Sat Dec 21 2019 .SYNOPSIS... High pressure in control this weekend. Warming trend this weekend and into the holiday week. A southern system may graze the area Sunday night into Monday, but most stay dry. && .NEAR TERM /THROUGH SUNDAY/... As of 640 PM Saturday... Intervals of cirrus will affect mainly the southern half of the CWA tonight. Current thinking is this will not be thick enough to prevent a sharp fall in temperatures this evening in the hollows and outlying areas. Across the northern portions of the forecast area, a lack of cirrus and high pressure allowed me to undercut NBM by several degrees for overnight lows. Hi res models along with the RAP/NAM continue to develop widespread dense fog across southeast OH tonight. While high pressure and a clear sky will be present, there is a significant amount of dry air just off the surface. So, despite the moist ground, current thinking is for fog to remain shallow and confined to river valleys. I'm thinking the models are tripping up on snow melt which is confined to west central OH. Having said that, I will continue to monitor trends to see if this forecaster gets humbled by the models. As of 134 PM Saturday... Cirrus deck continues to decrease in coverage this afternoon as a northern stream shortwave wave passes to the east of the area and upper-level moisture decreases. However, high clouds will once again be on the increase from south to north tonight ahead of a southern stream closed low near the Ark-La-Tex region. Cloud cover is expected to be greater across southern areas tonight, but skies should still be mainly clear across northern portions of the CWA. Since little to no wind is expected across the region tonight, areas where there will be a lack of cloud cover will have potential of fog and/or low stratus development. This appears most likely across portions of southeast OH and northwest WV, where the dewpoint depressions will be lowest. In addition, forecast soundings at PKB show a stout low-level inversion overnight so have added the mention of at least patchy fog and/or stratus in the region, but there is potential for this to become more dense. Any fog and/or stratus that does develop tonight should be slow to erode Sunday morning as surface winds will once again be light across the area so will be rather difficult to mix out. Otherwise, another quiet weather day is expected across the region as high pressure remains in control. Temperatures are expected to be around 10 degrees above normal for late December. High clouds will continue to increase northward throughout the day as a low pressure system in the northern Gulf of Mexico shifts across the southeast US. Precipitation associated with this system may just start to reach our southwest VA counties by Sunday evening, but thinking the near term period should mainly be dry. For now, will leave slight PoPs across parts of southwest VA at the end of the period with some light showers possible. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 250 PM Saturday... Southern stream slow moving stacked low pressure system passes south of the area this period, making its closest approach early on, Sunday night. The forecast continues the low chance for light rain out of a middeck for southwest Virginia and the far southern coal fields of WV for Sunday night through Monday morning. The southern stream upper level low forms an omega block like pattern, beneath which surface high pressure centered over the middle Ohio Valley and northern WV provides dry weather this period, along with above normal temperatures, given the northern stream well north of the area to start winter. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 250 PM Saturday... Ridging surface and aloft continue the dry weather Christmas Eve through Christmas Day, and into Thursday, with well above normal temperatures for Christmas and, needless to say, not a white one by any stretch. A weak front may bring light rain to the area late Thursday through Friday, as the ridging moves east of the area, but a better chance for rain comes next weekend, as a more amplified upper level trough drives a stronger cold front toward the area. The exodus / flattening of the ridge allows more cloud, and eventually rain, which results in slightly lower, but still above normal temperatures. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 650 PM Saturday... High pressure will reside overhead tonight amid intervals of cirrus...mainly across HTS/CRW/BKW. There are indications that dense river valley fog may form at PKB overnight, though confidence is not particularly high. I have introduced IFR VSBY there but no lower with this issuance. Elsewhere, VFR conditions should prevail though some brief MVFR reductions in VSBY are possible at EKN late tonight. Any fog that develops at PKB will lift and scatter by late morning with areawide VFR amid some mid and high clouds. Surface winds will remain light and variable. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY... FORECAST CONFIDENCE: High except medium at PKB ALTERNATE SCENARIOS: Dense fog may not develop at PKB overnight. 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 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H M M L L L L L CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z MONDAY... No widespread IFR conditions expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/RG NEAR TERM...30/RG SHORT TERM...TRM LONG TERM...TRM AVIATION...30