Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 280722 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 322 AM EDT THU JUL 28 2016 .SYNOPSIS... A weak east to west frontal boundary just to our north will move little. Several disturbances and copious moisture will bring heavy rainfall potential into the weekend. && .NEAR TERM /THROUGH TONIGHT/... Sent an update per latest radar and lightning data showing clusters of showers and storms moving north across the KY and wV border. Increase PoPs to likely. Additional showers or storms would develop overnight into the morning hours. A Flash Flood Watch remains in effect for portions of northeast KY, southeast OH and WV through 12Z Friday. Previous discussion below... 745 PM UPDATE... One band of showers and storms currently over E KY will shift into S WV and SW VA over the next couple of hours while dissipating as it does so. This disturbance passes to the east this evening while the quasi zonal flow becomes more amplified and out of the SW toward morning. This will allow a potent wave to track into the area for Thursday along with copious amounts of moisture. There still exists some discrepancy in the near term and short term models regarding the heavies axis of qpf with this feature with some taking it more into SE OH and along the OH River and others focused further SE. Complicating matters is extent of convection tomorrow which would enhance rainfall amounts. There should be quite a bit of cloud cover to limit heating but with the tropical atmosphere we are in it still looks like a general 1 to 2 inches with isolate higher amounts possible along wherever the main qpf axis sets up and in any convection. Flash flood watch will continues as is. PREVIOUS DISCUSSION BELOW... Broad and very moist upper level low over the southern Mississippi Valley this afternoon...having pw`s above 2 inches...will move northeast later tonight and Thursday. There is model consensus of tracking the system across our area and targeting our area with heavy rain potential Thursday...a general 1 to 2 inch swath with locally heavier amounts in any training of storms. Enough instability available for thunderstorms despite the expected cloud shield...but does not look like a severe thunderstorm threat scenario at this time. Thus...with much of the area nearly saturated from yesterday...have issued an FFA with this system from 12z Thursday to 12Z Friday for a good part of our area. Have started conservatively...omitting parts of southeast Ohio and far southeast portions of the area from the watch based mainly on not receiving yesterdays rainfall. Otherwise any convection this afternoon...mainly in the south...will wane fairly early this evening with loss of heating. As the above mentioned system approaches...there will be a large shield of clouds ahead of it. Given that this system is very nearly tropical in nature...it probably will not be as dependent on solid diurnal heating to generate convection as we are used to. Thus...more confidence in issuing the FFA. It will continue to be warm and muggy tonight with the high dewpoints and increasing clods overnight. For Thursday...somewhat cooler only because of the clouds and showers and storms...but quite muggy. Highs in the lower to mid 80s. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... One surface wave will be departing to our east to start the period...likely leaving a boundary somewhere in the vicinity. However, not much else to kick things off -- slightly rising 500mb heights and the next surface wave still to our west. So, have generally decreasing POPs Friday into Friday night but never went with a dry forecast due to the boundary and plenty of low level moisture around. Better chance of showers and thunderstorms on Saturday as another surface wave slides by. This feature is rather messy in the models, but still kept likely POPs across much of the northern and central CWA for now. May be able to fine tune as details resolve. Will have to continue watch for water issues, as precipitable water oscillates from 1.5 to around 2 inches with each wave. Will mentioning HWO, but not enough confidence to commit to any specific areas to extend the flash flood watch. A lot of it will depend on which areas receive the most rain today into tonight. Expect abundant clouds through the period, so instability will be somewhat limited and not seeing any organized severe threat. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Weather looks to remain unsettled for most of the extended period as additional disturbances move through the region. Drier weather possible early to mid next week as upper ridging strengthens across the region. Another front late week. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... VFR/MVFR conditions will prevail outside showers or storms overnight. Radar and lightning data indicate clusters of showers and storms moving north northeast across the KY and WV border. Although some areas show diminishing lightning, some storms could move over WV and southeast OH overnight producing mvfr/ifr conditions along their path. Areas of IFR patchy fog will develop over areas that receive rainfall and along some river valleys. IFR conditions is expected in dense fog, low stratus along river valleys through 12Z. Any fog will lift into low status by 13Z. After 12z Thursday...organized shield of showers and storms spreading northeast across the area with conditions lowering to MVFR/IFR especially in convection. CONFIDENCE AND ALTERNATE SCENARIOS... FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Fog potential tonight depends greatly on cloud coverage. 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 THU 07/28/16 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 L L L L L L L M M M M M HTS CONSISTENCY L L L L L L L M M M M M BKW CONSISTENCY H H H H H M L H M M M M EKN CONSISTENCY M L L L L L M M H H H H PKB CONSISTENCY M M L L L L M M H H H M CKB CONSISTENCY M M L L L L M M H H H H AFTER 06Z FRIDAY... IFR conditions in showers and thunderstorms through Thursday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch from 8 AM EDT this morning through Friday morning for WVZ005>009-013>020-024>032-036>040-046-047. OH...Flash Flood Watch from 8 AM EDT this morning through Friday morning for OHZ083-085>087. KY...Flash Flood Watch from 8 AM EDT this morning through Friday morning for KYZ101>103-105. VA...None. && $$ SYNOPSIS...ARJ/MZ NEAR TERM...ARJ/JMV/30 SHORT TERM...MZ LONG TERM...SL AVIATION...ARJ

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