Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 221853 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 253 PM EDT Fri Sep 22 2017 .SYNOPSIS... A mid-level ridge of high pressure will remain over the region through early next week. This will bring generally dry and warm weather conditions to the region. A slight cooling trend will occur by the middle of next week. && .NEAR TERM /THIS EVENING/... Stagnant. Probably the best word to describe the weather pattern over the Ohio Valley the past few days, but the warmth is another part of the story. NWS ILN has reached 91 degrees today and several other observation sites have either also gotten there or should in the next hour or two. Satellite imagery shows the greatest extent of cumulus development has been across Indiana and into west-central Ohio, along the fringes of the ILN CWA. Showers have developed in this area as well, which appears to be associated with an axis of slightly higher dewpoints (upper 60s to lower 70s). Over the next few hours, there will still be a slight chance of activity in the ILN CWA, mainly in the far southwestern / western sections. As skies clear and dewpoints drop slightly, min temps should actually get slightly lower than last night -- lower to middle 60s are expected. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... There will be little change in the pattern going into Saturday, aside from a slight northward shift of the ridge, but a couple of minor differences in the overall scenario. There is definitely a trend toward a drier air mass, with dewpoints falling into the mid 60s and precipitable water values dropping to closer to an inch than an inch and a half. This should effectively end any chance of pop-up diurnal showers, and in fact it would not be surprising to see most of the area remain clear on Saturday. The other issue is that with full sun and 850mb temperatures slightly rising from Friday to Saturday, temperatures may actually end up even warmer than on Friday (or even warmer than currently forecast for Saturday). This set of grids includes a slight increase from the previous run, allowing for close to 90 for the whole CWA. Based on conditions today, this could be conservative by a degree or two. Again, no big change going into Saturday night, so min temps will be similar (or just slightly lower with less moisture) to values on Friday night. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Large H5 ridge over the eastern U.S. continues to dominate the region`s weather pattern at the beginning of the period. It will combine with a surface high centered over the eastern Great Lakes to bring dry and much above normal temperatures to the region for the first half of the period. High temperatures in the upper 80s Sunday and Monday, will drop back into the mid 80s for Tuesday. With normal highs in the mid 70s, the forecast highs will be about 10-15 degrees above normal. Morning lows be in the lower 60s. By Wednesday, the models bring a cold front through the Great Lakes. The 00Z ECMWF is weaker with the H5 s/w. The GFS is a little stronger and more amplified with this feature and is supported by the ECENS means, along with the 06Z GEFS. So brought chance PoPs of showers and thunderstorms across the region Wednesday. Behind the front, a major pattern changes takes place as the H5 ridge in the ern U.S. is replaced with a trof. This brings in more of a seasonal airmass. Highs on Thursday will be down into the 70s, with Friday`s highs ranging from the mid 60s to lower 70s. With the CAA aloft, there could be some isolated light showers each day. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR conditions are expected through the TAF period, with calm or very light winds. Diurnal cumulus today will dissipate, and skies should remain clear to mostly clear through tomorrow. Fog appears less likely tonight than the past few days, so visibility restrictions were not included in the TAFs. The exception is for valley fog (MVFR/IFR) at KLUK. There is a very slight chance of a shower developing this afternoon at KDAY/KCVG/KLUK but much too low to include in the forecast. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...Sites AVIATION...Hatzos

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