Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 180622 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 122 AM EST Mon Dec 18 2017 .SYNOPSIS... Weak weather disturbances crossing the Ohio Valley tonight and tomorrow will bring clouds and a little drizzle to much of the area as temperatures remain mild. While clouds will likely hang on into Tuesday, temperatures will warm into the 50s ahead of the next weak cold front which will slip through the area rather quietly on Tuesday evening. This front will bring cooler temperatures and a little sunshine for Wednesday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Observations to our west continue to show a lowering of the ceilings and some reduction in visibility. This should spread northeast overnight in a continued moist southwest flow in the low levels. Weak WAA in the low levels along with this saturation should also allow for the development of patchy drizzle. Have kept the patchy fog wording, but added areas of fog to the northwest where models signal this region as the highest threat for visibility reduction. Temperatures will not fall that much from current readings as clouds and a little wind prevent substantial cooling. Lows will generally range from the mid 30s north/northeast to the upper 30s elsewhere. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Strong mid level ridge to remain over the southeast with westerly flow around its periphery over the Ohio Valley. Mid level vort axis to cross the area Monday with main s/w to our north. Weak vertical motion and continued thick low level moisture will lead to continued drizzle and clouds Monday into Monday evening. Mild temperature will continue with high temperatures on Monday from the lower 40s northeast to the upper 40s southwest. Depth of low cloud layer decreases as waa develops in the cloud layer with patchy drizzle diminishing Monday night. Some breaks may even develop in the clouds, especially over the west late. Temperatures will not show much diurnal fall with lows Monday night from the upper 30s north to the lower 40s south. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... A split flow pattern will set up through the middle of the week, with the ILN CWA largely remaining in between the two streams. A shortwave moving through the Great Lakes on Tuesday will likely not impact weather conditions over the Ohio Valley, beyond the generally cloudy skies that are expected to be in place. Continued warm advection will lead to ma temps in the lower to middle 50s. An associated cold front on Tuesday night will switch winds to the north and lead to cold advection. This front is also expected to come through dry, with a lack of deep-layer moisture and large-scale ascent. Confidence remains good that on Wednesday and Wednesday night, a southern stream low pressure system will pass south of the forecast area. As this occurs, an area of high pressure over the Great Lakes will have the ILN CWA on its southern fringes, resulting in light winds that eventually turn to the southeast by Thursday. Though there will be clearer skies in the drier air mass, the cold advection from the cold front Tuesday night will lead to a 10-12 degree drop in max temps from Tuesday to Wednesday, followed by a slight rebound after another day of mostly clear skies on Thursday. Forecast confidence begins getting lower by the end of the week, though there is large-scale agreement on low pressure developing and moving northeast into southern Michigan by Friday evening. This will lead to non-diurnal (warming) temperatures on Thursday night, with increasing chances for precipitation along and ahead of the associated cold front on Friday and Friday night. With regards to the low pressure system, timing, phase, and depth differences are still significant. This affects not only the timing of the greatest precipitation chances (which right now appear to be Friday afternoon, definitely subject to change) but also in the amount and duration of the precipitation, in large part due to the inconsistent handling of additional southern stream forcing and moisture transport. Friday does look like a day that will almost certainly favor rain as the main (or only) precipitation type, but some mix to snow behind the cold front could occur. By Saturday, differences in the modeled pattern become far too large to even attempt to approximate or assimilate into a gridded forecast. After the cold front passes on Friday night into Saturday, temperatures will certainly cool back down, but additional chances for precipitation are very uncertain at this point in the forecast cycle. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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Southerly flow over the region will bring in abundant moisture in the lowest few thousand feet underneath a lowering inversion today. Passing vorticity maxima at H5 along with a splotchy H7 upward motion vector are showing that disjointed forcing should bring patchy drizzle and IFR clouds to the region for the better part of the day. After about 20-21z, the larger upward motion has moved east of the region and drizzle should be ending at all locations. Low clouds will occasionally reach above IFR and into the MVFR category at times throughout the day, but more likely in the later day and evening. OUTLOOK...MVFR/IFR ceilings possible into Tuesday morning. MVFR ceilings and visibilities possible Friday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau/Hickman/AR NEAR TERM...Hickman/AR SHORT TERM...Binau/AR LONG TERM...Hatzos AVIATION...Franks is the U.S. government's official web portal to all federal, state and local government web resources and services.