Area Forecast Discussion
Issued by NWS Charleston, WV

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769 FXUS61 KRLX 241821 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 221 PM EDT Wed May 24 2017 .SYNOPSIS... Upper level low digs into the Tennessee Valley and brings chances of showers and storms through Thursday evening. Unsettled again for the weekend. && .NEAR TERM /THROUGH THURSDAY/... As of 215 PM Wednesday... Upper low continues to dig into the Mid Mississippi Valley with energy rotating into the CWA in the cyclonic flow. The weak instability has been overcome enough to get embedded convection within a stratiform rain shield, making the severe threat rather tricky given the directional shear profiles. Expecting more convection to fire in the dry slot in the wake of this shield where clearing has taken place. Wind and hail threat exists as well. Take the POPs down considerably tonight in this drier air after frontal passage from south to north with the absence of the heating. As the low continues to rotate into the northeast, additional embedded waves will be the source of forcing in the cold pool aloft heading into Thursday. There will also be a low level jet streak across the southern CWA which will help with some of the organization of the convection, but just in the general thunderstorm area from the SPC guidance. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 310 AM Wednesday... Upper low will be overhead on Thursday with scattered showers expected. An isolated thunderstorm is not out of the question with the cold temps aloft, but overall thunder threat is quite low. Ridging builds into the region by Friday morning and will briefly dry us out as warmer temperatures return as well. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 345 AM Wednesday... The pattern is starting to take shape for Memorial Day weekend and the potential for severe thunderstorms is growing. A stationary boundary will set up from west to east across the area and current guidance is indicating several short waves moving through the zonal flow Saturday and Sunday. Deep southwesterly return flow from the Gulf of Mexico will bring a warm and moist airmass into the region. Both the Euro and GFS indicate a plume of high mid level lapse rates moving into the area on the zonal westerly flow Saturday afternoon. BUFkit soundings in the GFS indicate this EML on Saturday with very high CAPE values on forecast soundings in the order of 2000 to 2500 J/Kg and 700mb to 500mb lapse rates around 8C/km. The uncertainty lies on timing of a short wave in order to break a decent Cap and tap into this unstable air. Confidence is still rather low due to timing disagreement between the models with the arrival of the short wave. However, I think there is at least enough ingredients in place that it warrants mention here that a severe outbreak is possible. Also, instability does weaken by Sunday but strong 0-6 km bulk shear with the passing of a cold front could produce severe storms as well. Finally, PWATs will be on the rise this weekend and GEFS indicates values about 2 standard deviations above normal. With the potential for thunderstorms and low flash flood guidance values due to rains today and on Thursday, there will be potential for flash flooding to occur. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... As of 125 PM Wednesday... Showers and thunderstorms moving into the area. Restrictions in ceilings in visibilities expected to arrive in the first 6 hours of the forecast, with some IFR possible in TSRA. Have avoided TEMPO groups given the large shield of precipitation moving in as opposed to a more scattered nature of precipitation. Once the heating ends and the dry slot from the upper level low moves in, take the visibility restrictions out with enough wind in place to keep the low levels stirred. Ceilings should come down however, with some IFR under 1kft after 06Z Thursday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY... FORECAST CONFIDENCE: Low. ALTERNATE SCENARIOS: Timing of TSRA or VCTS could vary. Amendments likely. Post thunderstorm environments later tonight may vary from 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 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 L L L L L L L L L L L L HTS CONSISTENCY L L L L L L L L L L L L BKW CONSISTENCY L L L L L L L L L L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY L L L L L L L L L L L L CKB CONSISTENCY L L L L L L L L L L L L AFTER 18Z THURSDAY... Upper level low keeps IFR chances in play through Thursday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...MPK/26 NEAR TERM...26 SHORT TERM...MPK LONG TERM...MPK AVIATION...26 is the U.S. government's official web portal to all federal, state and local government web resources and services.