Area Forecast Discussion
Issued by NWS Wilmington, OH

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138 FXUS61 KILN 201052 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 552 AM EST Mon Nov 20 2017 .SYNOPSIS... High pressure across the Ohio Valley this morning will move to the Carolinas this evening. A cold front will move east into the western Great Lakes tonight, and then across the remainder of the Great Lakes and Ohio Valley Tuesday into Tuesday night. High pressure will return to the region for Wednesday and Thanksgiving Day. Temperatures near normal will drop to below normal readings for Wednesday and Thanksgiving Day. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The region will be under the influence of a quasi-zonal upper level flow today. At the surface, high pressure extending into the Ohio Valley this morning will move toward the Carolinas by this evening. An embedded disturbance will bring some cirrus to the area, providing filtered sunshine. The pressure gradient will be tightest across our northwest, resulting in local southerly wind gusts in the 20 to 25 knot range. Temperatures will warm into the mid and upper 40s, which is near or slightly below normal. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... As the center of the high moves off the Carolina coast tonight, a cold front will move east into the western Great Lakes. We should see some cirrus overnight, some from the departing disturbance and more ahead of the next system. Winds will stay up with some local gusts developing overnight across the northwest as the gradient tightens well ahead of the cold front. Lows will range from the lower to mid 30s. On Tuesday, mid level s/wv will dig southeast into the Great Lakes. As this occurs, the cold front will move southeast, entering our northwest zones by late in the day. Models have trended wetter with this front, such that a chance of showers is now in the forecast for the northwest late Tuesday afternoon. Clouds will increase from northwest to southeast throughout the day. It will be breezy with wind gusts in the 20 to 30 knot range. Highs will range from the upper 40s northwest to the mid 50s southeast. For Tuesday night, mid level s/wv is expected to pivot east across the southern Great Lakes, pushing the cold front through our area. Again, the models have trended wetter, so now have a chance of showers for the northern/eastern zones where forcing and moisture will be the greatest, tapering off to a slight chance elsewhere. Precipitation will occur mostly in the evening, departing by early morning. Partial clearing is expected overnight with temperatures falling into the upper 20s to the lower 30s by morning. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The cold front will be east of the area by Wednesday morning, with cold advection occurring across the area, as surface high pressure begins to move into the region from the middle Mississippi Valley region. As the depiction of this cold front has continued to strengthen in the models, so has the cold air behind it, resulting in a 10-15 degree drop in max temps from Tuesday to Wednesday (a little more pronounced than in previous forecasts). A fast (if wavy) northern stream will set up across the northern CONUS / southern tier of Canada through the rest of the extended forecast period. The Ohio Valley will largely remain in a regime of weaker westerly / northwesterly flow to the south of the stronger jet, at least through the rest of the week, with some adjustment as a shortwave builds southward on Saturday. There has been some consolidation of model solutions with regards to this wave, and a cold front that will also move through the region at around the same time. With warm advection Friday night into Saturday morning (and likely non-diurnal temperatures) conditions should be warm enough to allow for rain as the precipitation type when the front crosses the area. Nonetheless, with limited moisture (as will be the case through the entire extended forecast period) PoPs will be kept on the low end. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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A ridge of high pressure across the Ohio Valley this morning will shift southeast through the day. Some high clouds will move into the area as a weak disturbance rotates east. Winds will become south, with local gusts around 20 knots near the northern terminals between 16Z and 22Z. For tonight, weak disturbance moves east, but more high level clouds will approach from the northwest as a mid level disturbance drops southeast into the upper Mississippi River Valley/western Great Lakes. Low pressure and a cold front with this feature will begin tightening the surface pressure gradient overnight. Above the surface, a fairly decent low level jet will move southeast into the region. This will bring the threat for non-convective LLWS conditions, developing between 04Z and 06Z. OUTLOOK...No significant weather expected.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Hickman SHORT TERM...Hickman LONG TERM...Hatzos AVIATION...Hickman

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