Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 210656 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 256 AM EDT Sat Oct 21 2017 .SYNOPSIS...
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High pressure continues through the weekend with mostly clear skies. A strong cold front and low pressure system crosses early next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 255 AM Saturday... Temperatures will be a bit warmer today than what we saw the last few days. High pressure slowly drifts eastward today and low level flow switches around to the SW...hence the warmer temps, but we will continue to see mostly clear skies, other than some cirrus passing through from the west. Also, looking at some warmer temps overnight with dew points coming up a bit with the warm moist SW flow. Tonight we will see the possibility for valley fog once again, but otherwise a nice night overall.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY/... 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 /TUESDAY NIGHT 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 /07Z SATURDAY THROUGH WEDNESDAY/... 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. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MZ/MPK NEAR TERM...MPK SHORT TERM...MZ LONG TERM...MZ AVIATION...MPK

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