Area Forecast Discussion
Issued by NWS Charleston, WV

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758 FXUS61 KRLX 220609 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 109 AM EST Thu Feb 22 2018 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH TONIGHT/...
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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.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 300 PM Wednesday... The frontal boundary lifts back northward as a warm front Thursday night with additional rain showers possible. Breaks in the clouds toward the South and strong SSW flow bump Friday afternoon temperatures back into the 60`s and 70`s. During midday, strong upper level forcing along the boundary brings yet another wave across the northeast Ohio River Valley where 1.2-1.5" PWAT exists generating moderate to heavy rainfall. At this time, the axis of heaviest precipitation for this wave looks to lie just north of our area in central Ohio through northeast Ohio and western PA. However - we still anticipate up to an inch of rainfall across our NW zones in eastern Ohio. Another wave moves through Saturday during the day, again generating moderate to heavy rainfall, with additional amounts around an inch possible in SE Ohio and near the Ohio Valley. These rains will lead to rises on streams and creeks and may lead to localized flooding, hence the issuance of the Areal Flood Watch. Rainfall amounts drop off fairly quickly to the SE, but with the front moving back and forth through the area with each passing wave, rainfall of some variety is likely everywhere across the CWA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 320 PM Wednesday... A welcome break in the synoptic pattern starts Saturday night as a short wave trough rotates through the upper Plains and Great Lakes Region. The strengthening jet ahead of it gives us one more wave of moderate to heavy rainfall overnight before the trough finally pushes this frontal boundary through the mountains and to the East coast by Monday morning. Models tend to dry this region out by sunset Sunday and high pressure quickly moves in behind for a quiet Sunday night through the end of the long term. Rainfall totals may again be quite high in the Saturday night/early Sunday timeframe, particularly in SE Ohio. Ohio Valley counties including WV counties near the Ohio River, all SE Ohio counties, and all NE KY counties could see an additional half inch to 1". Elsewhere rainfall totals are looking generally 0.25-0.5" with the passage of the cold front. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 100 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 moving into the Tri-state area, and will mainly be along and west of the Ohio River through the predawn, 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. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z 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 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY M M M L M L M M M M H L HTS CONSISTENCY H M H M M L L M M M L M BKW CONSISTENCY H H H M H H H H H H H M EKN CONSISTENCY M M M M M M M M M M M L PKB CONSISTENCY H H H H H H M M M M M L CKB CONSISTENCY M L M M H H H H H M M L AFTER 06Z FRIDAY... IFR possible at times in showers into the weekend.
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&& .RLX WATCHES/WARNINGS/ADVISORIES...
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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.
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&& $$ SYNOPSIS...MZ/MC NEAR TERM...MZ SHORT TERM...MC LONG TERM...MC AVIATION...MZ

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