Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 172045 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 445 PM EDT Tue Oct 17 2017 .SYNOPSIS... Dry high pressure with cool mornings and warm afternoons, with temperatures moderating through the weekend. A cold front crosses on Monday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 440 PM Tuesday... Opted to add the remaining coal field counties to the frost advisory. Fog limiting the diurnal trend is a concern, however per reports on social media there were some areas that got frost last night despite the fog...and forecast lows for tonight are lower than last night. Not everywhere will frost, but enough frost is expected that an advisory seems warranted. As of 235 PM Tuesday... A clear sky dominates much of the Ohio Valley and central Appalachians this afternoon. Dewpoints are running a bit below guidance at some locations which this leads to the frost conundrum overnight. With high pressure overhead amid a dry airmass, expect a quick fall in temps this evening. Using this afternoon`s dewpoints as a base and knocking a few degrees off guidance in our colder spots, we have elected to hoist a frost advisory for much of the area. The exception being the northern and central mountains where we ended the growing season today. Within the advisory area, expect dense main stem river valley fog to form once again, which will likely keep frost from forming in our more populated urban centers. I tried to hit this thinking in the headline reiterating areas away from main stem rivers and urban centers more likely to receive frost. Surface high shifts to the east on Wednesday with a s/w trof approaching from the west in the afternoon. Given the dry airmass in place at all levels, expect no impacts from this, with barely a cloud in the sky again. Highs were derived from met/mav/nbm blend which sends afternoon temps back above normal amid lowering RH values. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 230 PM Tuesday... A sfc high pressure will extend from the adjacent coastal waters of the Mid Atlantic, east and south into WV Wednesday night. The high center shifts overhead as it strengthened controlling the weather conditions. Very dry conditions expected through Friday night. Minimum RH values will dip into the 20s in parts of the area Wednesday afternoon, with 30s again widespread Thursday afternoon, becoming more confined to the mountains for Friday afternoon. By Saturday night, the high drifts east as an approaching cold front tightens the pressure gradient to pump moist and warmer air into the area under southwest flow. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 230 PM Tuesday... High pressure continues in control on Saturday through Sunday night. Will have to monitor each afternoon after mixing could bring low RH into the mid 30s. An increase in southwest flow is expected as the front approaches. An upper level trough and surface cold front to cross from the west Sunday night into Monday. Models are in agreement with the timing of FROPA as an upper level through passes through. After drying out behind the front Monday night, the slowing, deepening upper level trough over the area spells lots of clouds, and the chance for showers into Tuesday. Guidance suggests a warming trend through Sunday, followed by temperatures falling back to normal early next week. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... As of 340 PM Tuesday... High pressure remains in control through the taf period with light flow surface and aloft. IFR and VLIFR valley fog developing again tonight after 06Z at most terminals, with perhaps the exception of KHTS/KBKW. Fog will dissipate in the 13 to 14Z time frame with VFR conditions areawide thereafter. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Less fog may develop tonight than currently 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. UTC 1HRLY 21 22 23 00 01 02 03 04 05 06 07 08 EDT 1HRLY 17 18 19 20 21 22 23 00 01 02 03 04 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 H H H H H H H H L L L M PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 18Z WEDNESDAY... Dense valley fog possible each morning this week. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Frost Advisory from 2 AM to 9 AM EDT Wednesday for WVZ005>011- 013>020-024>034-039-040-515-517-519-521. OH...Frost Advisory from 2 AM to 9 AM EDT Wednesday for OHZ066-067- 075-076-083>087. KY...Frost Advisory from 2 AM to 9 AM EDT Wednesday for KYZ101>103- 105. VA...Frost Advisory from 2 AM to 9 AM EDT Wednesday for VAZ003-004. && $$ SYNOPSIS...ARJ/30 NEAR TERM...MZ/30 SHORT TERM...ARJ LONG TERM...ARJ AVIATION...30 is the U.S. government's official web portal to all federal, state and local government web resources and services.