Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 221827 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 227 PM EDT Tue May 22 2018 .SYNOPSIS... Cold front crosses tonight. High pressure to end the work week but more unsettled weather arrives in time for the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 200 PM Tuesday... Showers and storms have developed across most of the southern forecast area in a warm and unstable airmass. Farther north convection this morning left a more stable area but with some sunshine making it in now think we could get some storms to pop there as well. For the most part, do not expect this current activity to pose much of a threat due to a cap as evident on forecast soundings. The chance of stronger storms will arrive from the west late this afternoon into this evening. Storms are beginning to strengthen along and just ahead of a cold front which will move our way this evening, and cross the forecast area tonight. These storms should become strong to severe across western and central Ohio. The best area of instability extends into the far NW corner of the forecast area and coincides with a region of around 40kts bulk shear. This should allow the storms to remain strong to this point with strong winds the highest threat but some large hail is also possible. Instability quickly tapers off crossing SE Ohio and especially into WV/KY so storm intensity should decrease quickly across this zone. If a strong enough cold pool develops in central Ohio, it may be able to sustain stronger cells to around the Ohio River this evening. The cold front will cross tonight, moisture is beginning to decrease by this point, so capped POPs at scattered overnight. Continued and isolated thunder mention. Any lingering isolated showers across the mountains should taper off Wednesday with a dry day farther west. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
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As of 230 PM Tuesday... 5H ridge axis over the middle of the US will shift eastward with forecast area remaining under a weak flow regime at the mid and upper levels. Noted weak area of surface low pressure over the gulf with tropical characteristics in both the Euro and GFS models. Atmospheric column over the mid Appalachians undergoing a relative drying trend. Models are an general agreement in overall synoptic pattern with main differences noted in the details. Current thinking is that moisture should generally stay to our south this period. Expect morning fog in the river valleys due to trapped moisture at the low levels and subsidence inversion in place each day.
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As of 230 PM Tuesday... As 5H ridge breaks down response to northern stream wave working across, flow becomes more southerly, allowing more moisture to stream into the forecast area. Followed model blends throughout the period with a general diurnal trend of shower and thunderstorm activity each day. There is a possibility of slow moving convection with heavy downpours in this weak flow regime. Could see some local water issues Sunday and early next week as PW values creep upwards.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/... As of 200 PM Tuesday... Scattered thunderstorms are expected ahead of a cold front through this evening. As the cold front crosses tonight we should see another round of showers and maybe storms. Did not include any IFR in these, but anticipate needing to amened if storms approach any TAF site. Models fairly insistent on fog and low stratus formation tonight behind the rain despite keeping some flow. Have include this at most sites. Any fog should dissipate in the hour or two after sunrise with MVFR clouds lingering through the morning. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing and restrictions in showers and thunderstorms could vary. 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 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 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 H M M L PKB CONSISTENCY H M H H H H H H H H H L CKB CONSISTENCY L H H H H H H H H H H L AFTER 18Z WEDNESDAY... No widespread IFR expected. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MZ/30 NEAR TERM...MZ SHORT TERM...KMC LONG TERM...KMC/30 AVIATION...MZ is the U.S. government's official web portal to all federal, state and local government web resources and services.