Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 261928 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 328 PM EDT Tue Sep 26 2017 .SYNOPSIS...
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High pressure and dry conditions will be in place through tonight. A cold front will move through on Wednesday bringing the chance for showers and a transition to cooler temperatures.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Cu will dissipate this evening. There will be some high clouds that will begin to move into the area later in the overnight hours. Went close to guidance with low temperatures in the 60s. Winds will be light overnight. Mostly clear skies and light winds will allow for river valley fog to develop overnight.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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A cold front will move through on Wednesday. Moisture is limited with this feature, however isolated to scattered showers will be possible primarily mid day into the afternoon hours. Instability is limited therefore decided to keep thunder mention out of the forecast at this time. Any precipitation will taper off by Wednesday evening. Cooler air will filter into the area allowing for temperatures to drop down into the 50s Wednesday night.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Summary - High confidence in a cooler airmass than recent weeks that will be largely dry with no impact weather. Only threat of rain comes with glancing blow from shortwave troughs on Friday and Monday/ Tuesday, with both of these having greatest /relative/ shower chance in central Ohio. Details - At 12Z Thursday, a longwave trough over the northeast 1/4 of the United States will be sitting atop subtropical ridging centered across the lower Mississippi Valley. A Rex Block will be across the western intermountain states. Heights will progressively lower through Friday as a potent shortwave trough amplifies and moves through the Great Lakes. With bulk of kinematic forcing remaining north/east of the ILN forecast area, and overall positive- tilt nature of the trough, as well as offshore Gulf of Mexico trajectories ahead of the weak cold front attendant this system, think rain chances are best kept very low and kept closer to better low level forcing and /relative/ moisture (i.e., central Ohio on Friday morning into afternoon). Weak front will slip through the entire area by Friday evening with winds turning northerly and then northeasterly as strong surface high pressure builds southeast through the Great Lakes, coincident with shortwave ridging in the mid levels. A very dry troposphere will accompany this setup with a large PWAT minimum descending southeastward through the eastern half of the CONUS, with PWATS falling to 0.30 to 0.40". This all but guarantees a spectacular weekend with ample sunshine under deep blue skies, warm afternoon sun after chilly mornings in the 40s. In fact, a rogue upper 30F reading is not out of the question in central Ohio valley drainage sites like Newark or Lancaster. An ideal autumn weekend. Monday/Tuesday...large longwave trough again develops/amplifies southeastward through the wrn CONUS, forcing large scale height rises/ridging across the eastern CONUS. As high pressure moves southeast of the area, return flow slowly sets up but with still a dry trajectory out of the southeast initially. A little more uncertainty /timing/ with shortwave ejection out of the the western CONUS trough and attendant frontal zone trying to cross the larger scale ridge in the east. As we`ve seen in recent weeks, this will struggle to carry meaningful moisture far enough eastward, but there is enough of a deterministic and ensemble signal to at least carry a low rain chance north of I-70. Timing is uncertain and has been trending faster. Won`t warm things quite as quickly as 26.00Z ECMWF, but will most definitely trend back above normal in the last couple days of the forecast.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/... VFR conditions will start out the TAF period. Cu will continue to develop during the afternoon hours. Some fog will be possible overnight at KLUK and KILN. Went with MVFR conditions at KILN and IFR conditions at KLUK. A cold front moves through on Wednesday, however expect precipitation to be isolated enough that it was not included in the TAFs at this time. There will be additional cu on Wednesday. Winds will be light today through the overnight hours and pick up slightly during the day on Wednesday. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Novak NEAR TERM...Novak SHORT TERM...Novak LONG TERM...Binau AVIATION...Novak

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