Area Forecast Discussion
Issued by NWS Charleston, WV

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRLX 210547 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 147 AM EDT Sat Oct 21 2017 .SYNOPSIS... High pressure remains in control, with cool nights and warm afternoons through the weekend. A strong cold front and low pressure system crosses early next week. && .NEAR TERM /THROUGH TODAY/... As of 1240 AM Saturday...Temperatures are running a bit cooler than previously forecast with efficient radiational cooling under clear skies and light winds, so dropped low temperatures down a couple of degrees. With temps running a bit lower, there is some concern we will see a bit more fog as we will be much closer to crossover temperatures, but still not enough confidence at this time on what valleys will actually get the fog, so will leave fog forecast as is for now. As of 820 PM Friday... No changes. As of 150 PM Friday... Mainly clear overnight...though cirrus will try to spread into the area toward dawn. Another beautiful warm day Saturday with some passing cirrus. I continue to go a little below guidance for overnight lows, especially in the mountain valleys with near ideal radiational cooling once again. Highs on Saturday were nudged near the warm side of the envelope with 10 t0 15 degrees above average expected. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... As of 345 PM Friday... High pressure remains in control with deep southwesterly flow continuing to bring above-average warmth into the Mid-Ohio Valley and Central Appalachia. Low-level cloud cover will begin to build in from the southeast with the approach of a deep trough late Sunday. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 345 PM Friday... A briefly cut-off low will merge again with the northern jet and undergo cyclogenesis in the central to eastern CONUS by the start of the next work week. Models are beginning to hone in on a solution that suggests a storm track through the Ohio Valley though substantial track differences still exist. More expeditious guidance brings rain showers in starting midday Monday, although downsloping would favor a delayed onset until Monday night - closer to a consensus blend of guidance. An even greater delay in rain is possible if cyclogenesis is concentrated further south allowing greater warm air advection to push the frontal zone north. Nevertheless, the forecast depicts an elongated frontal zone passing through the area early Tuesday morning. Though exact frontal position is up for debate, high confidence exists for gusty, widespread rainfall Monday night through Tuesday. Being that cyclogenesis in this case is aided by strong divergence associated with a 120+ kt 300mb jet, and the deepening of this low tightens height gradients through the column, winds are expected to increase first with system onset Tuesday morning and again with the secondary cold front on the back side of the system Wednesday morning. The secondary cold front will usher in the coldest air experienced thus far this season with northwest flow behind. Showers may linger through Wednesday tapering off Thursday under the influence of a brief ridge. Pattern remains active with another trough to round out the week. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 145 AM Saturday... High pressure has pushed over the region and low level winds are weaker early this morning than they were last night. However, there remains a lot of uncertainty on how much valley fog will develop. Forecast model guidance is not interested in any fog until most recent runs pinning IFR fog at EKN around sunrise. Decided to use UPS Crossover technique for this mornings fog forecast, and although guidance is not indicating fog, EKN and HTS should at the very least hit their crossover temperatures, so have only included IFR conditions at those locations. CRW will be a bit tougher to fog so have left at MVFR for now. VFR conditions are expected through the day Saturday with dry high pressure remaining over the area. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: Medium overnight. ALTERNATE SCENARIOS: IFR or worse fog is still uncertain at this time. 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 SAT 10/21/17 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 H H H H M L 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 L L L L M H H H 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 06Z SUNDAY... Dense valley fog possible Sunday morning. Heavy rain at times early next week could also bring IFR conditions.
-- End Changed Discussion --
&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JMV/30/MC NEAR TERM...JMV/MPK/30 SHORT TERM...MC LONG TERM...MC AVIATION...MPK is the U.S. government's official web portal to all federal, state and local government web resources and services.