Area Forecast Discussion
Issued by NWS Charleston, WV

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207 FXUS61 KRLX 211936 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 336 PM EDT Fri Jul 21 2017 .SYNOPSIS... Thunderstorms through the weekend, with strong to severe storms possible this weekend. Frontal system passes early next week. Cooler high pressure crosses midweek. && .NEAR TERM /THROUGH SATURDAY/... As of 2 PM Friday... Bulk of convection across far eastern zones and starting to exit east. Behind line of convection, area of stratiform rain and lower clouds. Associated cloud cover is trying to thin a bit on satellite to our east, and it`s possible an additional shower or storm could refire, but initial thought is atmosphere is probably fairly worked over, but left a slight chance to chance in for the remainder of the evening. Otherwise, another warm and humid night on tap. Thinking if there are many breaks in the clouds overnight we could see widespread fog development. As has been the case, models are struggling to depict the overall pattern, and this is the case for tomorrow. General consensus is for frontal boundary to lift back north on Saturday, with continued warm and humid conditions. Wave of low pressure moving east along the boundary, combined with general warm and unstable conditions, will lead to additional rounds of showers and thunderstorms, particularly across the north, where strong to severe thunderstorms will be possible, as 0-6km shear increases to 35-40 kts. SPC has northern zones in a slight risk for Saturday, with much of the southern zones in a marginal. In addition, heavy downpours are expected, with the possibility of localized flooding issues again, as pw values rise to 1.7 to 2+ inches. As far as a heat advisory on Saturday, am getting heat advisory conditions across parts of the lowlands on Saturday, however, still uncertain as to where/coverage of greatest precipitation will be. Have elected to have the midnight shift reevaluate the forecast and determine if one is necessary. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
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As of 330 PM Friday... Models differ on timing of a low pressure system moving through the Great Lakes Saturday night through Sunday night. Leaned toward the NAM solution for this period as it seems to have a handle on current features. Upper level system tracks to our north Saturday night into Sunday. As it passes, trailing cold front will push southward across the CWA. With soupy airmass in place, Any showers or Thunderstorms with the front could produce heavy downpours with PWs near 2 inches over much of the area. Low pressure over the plains will finally lift and cross the Great lakes Sunday night Through Monday night. Left over frontal boundary over the region will lift north as a warm front and trailing cold front will push approach the area Sunday Night and exit Monday evening. SPC has us in a slight risk for severe wx Sunday with afternoon heating and lifting frontal boundary along with increasing instability throughout the day. Airmass stays rather soupy and water concerns are defiantly possibility Saturday night through Monday night. WPC has a slight risk of excessive rain for Saturday night and Marginal risk through Monday.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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As of 330 PM Friday... Cooler and drier air associated with high pressure that builds across the region on Tuesday and lasts through Thursday. This will bring a welcome relief from the heat and humidity. Another system or complex may approaches from west Thursday night into Friday. This will bring showers and thunderstorms back into the forecast.
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&& .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... As of 200 PM Friday... Still quite a bit of convection across the mountains, affecting sites KEKN and KBKW through at least 20Z, with -shra at times through at least 23Z. Overnight, most of the convection should decrease, although an isolated storm could still develop, with brief MVFR or IFR conditions. After 04Z, widespread MVFR/IFR fog is expected to develop, with improvement to vfr after 13Z. On Saturday, showers and thunderstorms will be on the increase once again, particularly after 16Z. Strong gusty winds, along with small hail and IFR conditions are possible with any storms. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Additional convection could develop this evening. Widespread fog may not form 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. 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 M L HTS CONSISTENCY H H H H H H H H H H H L BKW CONSISTENCY H H H H H H H H H H M L EKN CONSISTENCY H H H M H H M L H H M L PKB CONSISTENCY M M M H H H H H M M M L CKB CONSISTENCY H H H H H H H H L H H L AFTER 18Z SATURDAY... IFR possible Saturday and Sunday in heavy showers and thunderstorms. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JS/SL NEAR TERM...SL SHORT TERM...JS LONG TERM...JS AVIATION...SL

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