Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 230713 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 313 AM EDT Fri Aug 23 2019 .SYNOPSIS... Cold front finally exits to the south today. High pressure with dry, cooler weather for the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 235 AM Friday... In the midst of strengthening lower level 900-800mb frontogenesis, so expect the coverage of showers to increase through sunrise this morning. A weak wave of surface low pressure is keeping the forward motion of the cold front to a minimum but should see the front clear our portion of the mountains after 15Z. The POPs continue in the wake of the front, however, due to a 500mb axis embedded in the very broad cyclonic flow over the Great Lakes. Much drier air at the surface, lower, and mid levels moves in with this wholesale airmass change once the wave aloft passes and high pressure builds over the Great Lakes. Lower dewpoints tonight allow for lows to drop back into a more comfortable range after a few days of heat across the region. && .SHORT TERM /SATURDAY THROUGH MONDAY/... As of 313 PM Friday... Mainly dry conditions are expected on Saturday due to the influence of an expansive surface high centered in Quebec. However, can`t completely rule out a few isolated showers/storms Saturday afternoon in extreme southeastern zones where better quality moisture and instability is expected (dewpoints in the low/mid 60s and CAPE around 1,000 J/kg). The greatest chance of any precipitation will be in southwest VA where low chance PoPs are in place. Elsewhere, the atmosphere will be very dry with surface dewpoints in the mid/upper 50s, yielding PWATs between a half inch to an inch. With high temperatures forecast to reach the upper 70s/low 80s, fantastic weather is expected with comfortable humidity levels. As the aforementioned high pressure shifts east towards the Canadian maritimes on Sunday, return flow will give temperatures a boost of a few degrees. This should translate to highs in the low 80s across the lowlands on Sunday afternoon, just a degree or two below normal for this time of the year. Upper ridge axis across the Great Lakes should provide for a mainly dry forecast once again, but some low PoPs are included across southern areas as a cut-off low rotates east of the area in the Mid-Atlantic region. Regardless, with little to no instability expected and subsidence in place, most of the region should be dry. By Monday, upper ridge axis continues to push to the east and a shortwave trough will move across the Midwest. This leading shortwave trough will eventually become absorbed by a larger scale trough emerging from the northern Plains late in the short term period. However, the leading shortwave trough may get close enough to our region on Monday afternoon to bring an increase in PoPs from west to east through the day, as the GFS suggests. The ECMWF, however, is slower with the arrival of the leading trough and thus, holds off on most of the precip towards mainly the long term period. For now, went with a consenus blend of models which does support slight/chance PoPs across the region Monday afternoon into the evening. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... As of 313 PM Friday... By Monday night, the aforementioned main trough axis will extend from the Canadian Prairies southeastward into the Ohio Valley, pushing a cold front through our region on Tuesday. This will bring widespread showers and thunderstorms throughout the area on Tuesday. With models projecting PWATs around 1.50-1.75 inches, heavy downpours will be possible. There also will be some modest shear, with models at this distance suggesting around 30 kts in the 0-6 km layer. However, instability will be in question given the abundant cloud cover that is expected. Precipitation will end from west to east throughout the day on Wednesday, with high pressure building in across the Ohio Valley. This feature should then be in control through the remainder of the week, keeping conditions mainly dry and seasonal through the end of the long term period. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... As of 140 AM Friday... Expecting shower development to be on the increase over the next 6 hours, and limit the activity to only showers without thunder. The visibilities should not get worse than MVFR in shower activity, but do expect a gradual lowering of the ceilings to MVFR or possible IFR through 14Z. Not all terminals will see the IFR ceilings. Cold front sinks southward, and areas north of the boundary will dry out in the lower levels Friday. EKN/BKW/mountains are the last locations to return to VFR prevailing conditions. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of ceilings lowering could vary. Brief IFR visibilities possible in heavy rain. 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 FRI 08/23/19 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 M M M M H M H H HTS CONSISTENCY H M L L M M L H L L H H BKW CONSISTENCY H H H H M L L M H H H H EKN CONSISTENCY H M L L M M M M H L H M PKB CONSISTENCY H H H H M L H H H H H H CKB CONSISTENCY H H H H H H M H M H H H AFTER 06Z SATURDAY... IFR fog possible early Saturday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/RG NEAR TERM...26 SHORT TERM...RG LONG TERM...RG AVIATION...26 is the U.S. government's official web portal to all federal, state and local government web resources and services.