Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 120841 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 341 AM EST Sun Nov 12 2017 .SYNOPSIS...
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A weak low pressure system will track across the region today, bringing rain to the area. Cool and dry weather will settle back in for Monday and Tuesday, before another bout of rain reaches the region Wednesday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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H5 s/w will amplify today as it swings east from the upper MS Valley and into the Ohio Valley. Meanwhile a weak sfc low will develop and track into the fa this afternoon. We are already seeing some isentropic lift producing light pcpn across parts of Indiana into nw Ohio. Bulk of the pcpn will wait until later today when convergence associated with the low moves into the region. Kept the likely to categorical PoPs for late this afternoon. Highs will be limited to the lower 40s in West Central Ohio, but will increase to the lower 50s in nrn KY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
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The shortwave will swing across the region tonight. This will push the area of pcpn through the region quickly this evening. Critical thicknesses drop on the backside of the system. In the nw, some wet snow may briefly mix in prior to ending. Low level moisture will linger into Monday morning, keeping the skies cloudy. High pressure building in from the west should bring partial clearing by afternoon. Highs will remain below normal, ranging in the mid to upper 40s. The high pressure will swing across the region Monday night, bringing mostly clear skies. Temperatures will drop back to around freezing. The region will be on the backside of the Ohio on Tuesday. Despite some sunshine, highs will remain cool, ranging from 45 to 50.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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Going through the rest of the week, there are two main concerns to look at. The first is with a developing cold front on Wednesday. Model agreement is in good shape regarding timing and placement for this system, and categorical PoPs will be brought through the area in association with the front. This front is attached to a surface low that will be moving north of Lake Superior on an eastward track, with the mid-level trough strengthening as it moves across the Great Lakes. It was a close call with regards to temperatures early Wednesday morning, but with some slight warming possible before sunrise in the southerly flow, this forecast will keep all precipitation rain. Ahead of the front, temperatures should be slightly warmer -- with highs in the lower to middle 50s. It will be a relatively quick transition through high pressure on Thursday and the return to southerly flow on Thursday night into Friday. The next system, moving in for Friday and Friday night, is a little more complicated -- and thus it is not a surprise that model solutions are not as consistent in its depiction. There will initially be a surface low and mid-level trough moving across Canada, but a secondary trough is expected to develop ahead of a jet streak coming across the central plains. This will allow for another surface low to develop very close to the area, which may allow for a relatively quick passage of both warm and cold frontal processes across the Ohio Valley. Timing is the biggest issue, with slow solutions (12Z ECMWF) and faster solutions (06Z GFS) running a solid 12 hours apart. PoPs will be kept in the chance category until this issue is resolved, though it is certain that most (if not all) locations will receive precipitation at some point during the Friday / Friday night time frame. With lots of upper support and wind energy, forcing should not be in question with this system. Have also used non-diurnal temperatures heading into Friday morning, and moved high temperatures up slightly on Friday from the previous forecast (middle 50s to near 60). Behind this system, the first part of next weekend looks drier in a cold advection pattern.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/... Have pushed back the timing of the onset of rain in most areas by about 1-2 hours this afternoon and evening. General trend of the forecast remains unchanged. One exception here is the tower at CVG that would likely be in low clouds and have a significantly lower tower vsby than surface vsby towards the end of the forecast. Surface high pressure centered over New England will move offshore today as low pressure tracks into the CWA this afternoon and strengthens slightly. Until rain begins as the low enters, high clouds will lower somewhat through this morning. As the low develops, deteriorating conditions will result in IFR ceilings. Visibilities should remain MVFR for the most part, but some IFR visbilities may develop where winds switch to the northwest/north before rain ends from west to east tonight. After the rain ends towards 2-3z in western TAF sites, cigs will remain IFR and could be LIFR at CVG, with vsbys still in the MVFR category with BR. OUTLOOK...MVFR, perhaps IFR, ceilings to linger into Monday. MVFR/IFR ceilings and MVFR visibilities possible Wednesday into Wednesday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR/Sites NEAR TERM...Sites SHORT TERM...Sites LONG TERM...Hatzos AVIATION...Franks

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