Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 230604 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 104 AM EST Tue Jan 23 2018 .SYNOPSIS...
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Colder air will filter back into the region tonight and Tuesday. A chance of rain and snow showers will be observed Tuesday as an upper low tracks through the Great Lakes. High pressure will then bring dry conditions through the end of the week.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/... A cold front has entered our western CWFA this evening. Ahead of it, showers and embedded thunderstorms have developed in a region of forced low level jet convergence and instability. Precipitation should exit our eastern CWFA by early morning. We should see a brief dry slot work in behind the front before clouds increase from the west once again in association with an upper level low. Models rotate a vort lobe around the upper level low into our northwest forecast area late, which should bring an increase in showers by then. Best chance is still poised for our west/northwest. Winds will pick up overnight, especially late, as stronger CAA pushes into the area along with a tightening pressure gradient. Lows will range from the upper 30s west to the lower 40s east. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... On Tuesday the closed mid/upper low will track east through the Great Lakes. Southwest to west winds of 15 to 25 mph with gusts to 35 mph will usher colder air into the region Tuesday. Expect nearly steady temperatures in this CAA pattern. Lift from the low and steepening low level lapse rates will lead to scattered showers Tuesday into Tuesday night. Most areas will see rain initially then changing to snow from nw to se through the day into the evening. Little snow accumulation is expect prior to ending Tuesday night. Temperatures to drop to lows in the mid to upper 20s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Behind the low pressure system exiting the area on Tuesday, the coldest air aloft will be moving through the area on Wednesday. This sets up Wednesday as the coolest day of the week, especially as surface winds will remain westerly -- neutrally-advecting at best. While the overall pattern will be gradually switching away from troughing and toward ridging, the 500mb flow will remain wavy, and there are expected to be one or two waves moving through the Ohio Valley and southern Great Lakes in the Wednesday-to-Thursday time frame. At the very least, this may lead to some periods of increased cloud cover (another factor to keep temperatures down on Wednesday) along with the possibility of some light precipitation. Based on the 06Z/12Z model runs there does not seem to be enough consistency in the placement of the forcing to add any PoPs to the forecast yet (a jet-induced stripe of weak ascent previously depicted for Wednesday has almost disappeared from the current runs). Broad surface high pressure will move east into the area from Wednesday night into Thursday, though it will be centered south of the ILN CWA. By Thursday morning, ridging over the Mississippi Valley will become more prominent, and increasing significantly by Thursday night into Friday. This will bring dry conditions and gradually warming temperatures through Thursday and Friday, remaining warm going into Saturday. In fact, the continual southerly flow will likely keep temperatures from falling much (if at all) on Friday night. Behind the departing surface high, and with troughing developing over the plains, moist flow from the Gulf is expected to move into the Ohio Valley again over the weekend. This very basic statement is about the only thing still in good agreement for the weekend forecast -- 00Z and 12Z operational GFS/ECMWF runs have eschewed consistency in favor of drifting further apart in their timing and amplitude depictions of the weather features through this period. In particular, it is the depth and speed of the upstream trough that seems to be a source of inconsistency regarding upcoming precipitation timing. The 12Z operational GFS is very fast and progressive with the trough, while the 12Z operational ECMWF is slower and stronger, with greater amplitude. This manifests in a roughly 24-hour difference in the timing of the greatest chances for precipitation. The 12Z GFS timing is a little more consistent with its own past runs, while the 12Z ECMWF timing is much slower than its 00Z cycle. However, it is definitely worth noting that several GFS ensemble members do not support the operational run, instead supporting the slower ECMWF solution. This all works to provide low confidence in how exactly the scenario will play out, though rain appears certain to occur at some point. Until timing gets into better agreement, PoPs will be capped at 50 percent. Conditions ahead of the trough will likely remain warmer than normal, but should cool down as an associated cold front moves through at some point in the period. Eventually, temperatures will probably end up close to the climatological normal by Monday, with drier conditions favored behind the front. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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Line of convection has moved east of the tafs, as a cold front currently splits the region. Expect the front to clear the eastern tafs by 07Z. Clouds have gone scattered as the post frontal dry slot has worked in. Clouds will go broken again as lift increases ahead of embedded disturbance rotating around the upper level low. Ceilings should be VFR as the clouds move in. Models are consistent in bringing an area of showers up through mainly the Whitewater and Miami Valleys after 09Z. Added tempo MVFR vsbys at KDAY with this pcpn. Elsewhere pcpn should be scattered in nature, so just went with vcsh. H5 low will lift up through the region today, causing ceilings to lower to MVFR. West to southwest winds will affect the tafs throughout the day with gusts in the upper 20 to the lower 30 kt range. Scattered showers will continue as the caa and lift from the upper low combine over the area. Upper low will pull out tonight, allowing winds to gradually diminish during the overnight hours, but MVFR ceiling will linger. OUTLOOK...MVFR ceilings likely to linger into Wednesday. MVFR ceilings and visibilities possible Saturday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman/AR NEAR TERM...Hickman SHORT TERM...AR LONG TERM...Hatzos AVIATION...Sites is the U.S. government's official web portal to all federal, state and local government web resources and services.