Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 260446 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1246 AM EDT Thu Apr 26 2018 .SYNOPSIS... High pressure building across the Great Lakes will keep dry weather conditions over the area tonight through Thursday. A weak cold front may bring few showers on Friday. High pressure and drier air are forecast to return on Saturday and persist through Sunday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Though a few patches of stratocumulus clouds are persisting, most of the forecast area is being enveloped by high clouds, in advance of the low currently progressing into the middle Mississippi Valley region. The one segment of the CWA currently escaping much in the way of any cloud cover is the northwestern section, where it would not be surprising to see temperatures take a sharper drop than previously forecast. Min temps were generally left unchanged through the rest of the CWA, but were raised slightly under the thicker high clouds in the south, and lowered slightly in the clear skies in the NW. The only other item of interest tonight is the possibility for fog. The signals from GFS/NAM numeric guidance, HRRR visibility, and RAP RH plots, have been -- at best -- spatially inconsistent. However, all have indicated at least a possibility of some visibility restrictions overnight. Surface dewpoints are highest (upper 40s) in the southeastern ILN CWA, which is also where winds are likely to become the lightest. Forecast confidence is too low to include fog everywhere, but this will be added into about a third of the CWA, generally along and southeast of a line from Licking County OH to Bracken County KY. Previous discussion > Surface analysis shows high pressure building into the Great Lakes, pushed by a northwest flow aloft. Low clouds lingering in a northerly low level flow behind departing surface low pressure will continue to erode gradually this evening as drier air works in, while high clouds move in as the upper flow becomes westerly. This will leave partly cloudy to mostly clear skies by later tonight, with more clouds remaining over eastern locations. Low temperatures are forecast to range from around 40 north up to the mid 40s south. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... For Thursday and Thursday night, we will find weak surface high pressure extending across the Great Lakes into the State of Ohio. Meanwhile, low pressure will be traveling through the Tennessee Valley. Precip with this rather compact low is expected to remain south of the ILN area, while cloud cover will be greater along and south of the Ohio River closer to the low pressure. Generous solar radiation will help boost temperatures up into the low to mid 60s for highs. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... An upper level s/wv and its associated weak cold front will move east across the region on Friday. These features will bring some clouds and perhaps a few showers, mainly post frontal. Highs will range from the lower to mid 60s. Models have trended much deeper/more pronounced on a long wave mid level trough digging into the Great Lakes and Ohio Valley Friday night into Saturday. Embedded s/wv energy digging on the back side of the developing mid level trough will accompany a cold front, bringing some clouds and a chance of showers, mainly across the northern zones Friday night into early Saturday. Partly to mostly sunny skies are forecast in the wake of the front on Saturday, but temperatures will show a downward trend with highs ranging from the lower 50s northwest to the lower 60s south/southeast. For Saturday night into Sunday, surface high pressure will build into the region from the northwest. Clear skies and winds becoming light Saturday night will probably result in some frost as temperatures drop into the lower to mid 30s. Will mention this threat in the HWO. On Sunday, despite sunshine, temperatures will be cool, mainly mid and upper 50s. As we head into early next week, the surface high will move east while a mid level ridge moves into the Great Lakes and the Ohio Valley. Dry weather, return flow, and sunshine, will result in a warming trend with all locations seeing 70s by Tuesday. There remains timing differences in the models on how fast mid level ridge will move east, which will eventually allow moisture and a cold front to move toward the region by mid to late week. For now, a chance of showers and thunderstorms will continue in the forecast for later Wednesday into Wednesday night well ahead of the cold front. It will remain warm with highs in the 70s again on Wednesday. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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All TAF sites are VFR this morning with surface analysis revealing extremely weak flow. The next upper level disturbance is currently over the Oklahoma/ Arkansas border with a widespread cirrus canopy across the south. The main concern with the forecast will be the potential for some reduced visibilities across the area. The widespread cirrus across the south will likely hinder fog development, with the weak flow helping to aid in fog development. Surface analyses reveals a weak trough axis across central Ohio and this is what high res models appear to be focusing on. The tempo group at KILN and KLCK seem like a great way to go and have kept them going. Think KCVG/ KLUK/ KCMH will all be a tad to displaced from the trough axis to see much in the way of visibility restrictions. High clouds will continue across the south today, but VFR conditions will prevail. Light east winds will back more northerly by the end of the taf issuance, but will be very light (perhaps light and variable at times). OUTLOOK...MVFR ceilings are possible Saturday morning.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio/Hatzos SHORT TERM...Coniglio LONG TERM...Hickman AVIATION...Haines

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