Area Forecast Discussion
Issued by NWS Wilmington, OH

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218 FXUS61 KILN 261042 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 642 AM EDT Mon Jun 26 2017 .SYNOPSIS... An upper level trough swinging through the Great Lakes will bring a chance of showers and thunderstorms this evening and tonight. High pressure will provide dry weather at midweek with increasing precipitation chances toward the end of the week as temperatures warm to near normal. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure centered across the Mississippi valley is providing a mostly clear morning. Nocturnal AC that had been affecting the region has been decreasing. H5 will dig down into the Great Lakes today. However models have delayed the development of showers and thunderstorms from this afternoon to tonight. So just expect diurnal cloud development today. Temperatures will still be 5-10 degrees below normal, with highs in the lower to mid 70s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Out ahead of the s/w, a 30-35kt low level jet will combine with 500-1000 J/kg of lingering CAPE cape this evening to support showers and thunderstorms dropping e from Indiana. Expect the convection to be scattered in nature as it works across the region. Lows tonight will be in the lower to mid 50s. Precipitation could be lingering in the southeast early Tuesday, but will move e into the Appalachians by mid morning. Tuesday afternoon will be dry with highs again in the lower to mid 70s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Dry high pressure is expected to remain in control of the weather Tuesday night through early Thursday, influencing conditions through the middle part of the week. With a turning of winds to the south on Wednesday, a more appreciable warmup will begin, with temperatures returning to the 80s. As a more progressive pattern begins to set up for Thursday and beyond, model differences become more pronounced, leading to lower confidence -- especially in precipitation timing near the end of the week and into the weekend. There is agreement that a frontal zone will set up east-to-west across the southern Great Lakes beginning early Thursday, with the ILN CWA in the warm sector within solid deep-layer southwesterly flow. As convection develops at the north end of this warm sector, and along the frontal area, there will eventually be some propagation downstream which should impact the ILN CWA -- likely beginning on Thursday afternoon, and then again as additional waves of precipitation occur going into Friday. How much of the CWA remains capped is a question, as is the exact position of the front. However, model runs have trended a little southward with precipitation chances, increasing the probability for storms in the ILN CWA on Thursday and Friday (especially in the northern half of the CWA). PoPs have been increased slightly through this time period, but with little change to temperatures, as there is confidence in continued southwesterly flow through the period. In addition, with ample instability and at least somewhat favorable deep-layer shear, some strong to severe storms could be possible on Thursday and Friday. Differences in the evolution of an upstream trough going into the weekend will preclude more than very low confidence in the forecast Saturday into Sunday. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... A dry airmass will see high based cu develop and become more broken as the day wears on. This is in response to a mid level shortwave pushing through the Ohio Valley early in the day, followed by a deeper low pressure center crossing just north of the area later in the day. Skies should clear later in the overnight hours as subsidence behind the upper shortwave combines with a building surface high pressure system to the west. Models are showing some showers over the region from the forcing of this system, but a lack of moisture in the lower levels has me keep the forecast dry today at all TAF sites. Previous discussion mentioned thunder and the region is in general thunder for today, but initial thoughts are that any showers that would develop would be lacking in lower level moisture and not be deep in nature - at least not deep enough for a charge separation necessary for thunder. Any showers that do present themselves later today will be VFR. WNW winds will increase to around 10 to 12kts during the day on Monday, with a few gusts to 20kts possible. OUTLOOK...Showers and thunderstorms are possible Thursday and Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR/Sites NEAR TERM...Sites SHORT TERM...Sites LONG TERM...Coniglio/Hatzos/Sites AVIATION...Franks is the U.S. government's official web portal to all federal, state and local government web resources and services.