Area Forecast Discussion
Issued by NWS Charleston, WV

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272 FXUS61 KRLX 221116 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 616 AM EST Thu Feb 22 2018 .SYNOPSIS... Cold front stalled across the south early this morning, and meanders through the end of the week as surface waves pass. Areas of significant rainfall possible into the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 600 AM Thursday... Light to moderate rainfall continues across SE Ohio, amounts are getting into the 0.5-0.75 range. This precip is gradually shifting north...a trend which should continue until the surface wave starts moving across and pulling the precip shield eastward with it. As of 100 AM Thursday... Surface boundary currently stalled out across southern coal fields and southern mountains, with a surface wave beginning to move out of the lower Mississippi Valley. Also have 500mb shortwave trough coming out of the southern plains. All of this is resulting in an area of precipitation stretching from Texas into the middle Ohio River Valley. High res models seem to have a decent handle on this, so used a blend of HRRR and NAMNest to tighten up POP gradients. Through this morning, have an area of 100 POPs developing across SE Ohio as the surface wave approaches and nudges the front back to the NW. As the surface wave passes, have the higher POPs crossing the Ohio River and gradually decreasing as the front drifts back to the SE -- away from the better mid and upper level support -- and stalls in or near the SE corner of the forecast area. Have 0.5-0.75 inches of rain with the wave today, mainly along and NW of the Ohio River. Plan to keep an eye on new data as it rolls in this early this morning to help decide if the flood watch need to be moved earlier -- but with the current QPF think we can handle this first wave with no significant issues and have not changes the watch timing. The next surface wave in the train approaches tonight, with a similar trend of pushing the surface boundary back north. Have an area of high chance POPs along the front tonight. Opted to not go likely at this time due to lack of mid and upper level support, anticipating scattered showers. Temperatures through the period are very tricky, as the surface boundary provides a rather sharp gradient. Used a blend of high res models on the hourly temps trying to capture its meandering over the next 24 hours. However this leads to rather low confidence, as a 20 mile change in the boundary position will result in up to 10-15 degrees difference in temperatures at any given spot. In general terms... it will be very mild across the SE with highs today near 70, but much of SE Ohio and NE Kentucky will struggle to bump above 50. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 200 AM Thursday... Frontal boundary lifts back north Friday with additional waves moving along the front, enhancing precipitation, particularly across northern zones where flood watch is in place. The front will sag south, and waffle around the area in vicinity of Ohio River late Friday into Saturday, before finally lifting back north again late Saturday, as a strong low pressure system moves northeast out of the southern plains. Good southwesterly flow/llj/moisture tap from Gulf, with PW values rising to over 1.4 inches. Time period of greatest precipitation looks to be Saturday night/early Sunday, with a general inch and a half of qpf, if not more in spots. Drying trend gradually takes place on Sunday, as high pressure builds in behind departing cold front. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 210 AM Thursday... High pressure in control during the period with dry and mild conditions. && .AVIATION /11Z THURSDAY THROUGH MONDAY/... As of 600 AM Thursday... Not a good day for non-instrument flight as low MVFR and IFR conditions are expected across most of the forecast area through the TAF period. A surface wave will move through today, with rain showers. These are already in place across much of SE Ohio, and will remain along and west of the Ohio River early this morning before shifting eastward later this morning into this afternoon. Winds are mostly out of the N to NE currently, but as the wave passes winds will vary quite a bit from place to place. Expect IFR stratus and rain/fog again tonight with a surface boundary stalled in the region. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of MVFR/IFR conditions may vary through the TAF period. 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 02/22/18 UTC 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 EST 1HRLY 05 06 07 08 09 10 11 12 13 14 15 16 CRW CONSISTENCY L L M H H H H H H H M M HTS CONSISTENCY H H M M L H M H H H M M BKW CONSISTENCY M M M M M H H H H M L L EKN CONSISTENCY M M M M H H H H H M L L PKB CONSISTENCY H H M M H M M M H H L L CKB CONSISTENCY M M M H H L L H H H L L AFTER 12Z FRIDAY... IFR possible at times in showers into the weekend. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flood Watch from this evening through Sunday morning for WVZ005>011. OH...Flood Watch from this evening through Sunday morning for OHZ066-067-075-076-083>087. KY...Flood Watch from this evening through Sunday morning for KYZ101-103. VA...None. && $$ SYNOPSIS...MZ/SL NEAR TERM...MZ SHORT TERM...SL LONG TERM...SL AVIATION...MZ

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