Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 281430 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1030 AM EDT Fri Apr 28 2017 .SYNOPSIS... High pressure will move east early today. A frontal boundary will develop into the region this afternoon and linger near the area into Sunday, causing unsettled weather through the weekend. Cooler temperatures will filter in behind the front next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A developing warm front will lift north across the Tennessee Valley through this afternoon, possibly pushing north into southern portions of our fa through this evening. There remains some uncertainty among the models as to how far north this boundary will make it and as a result where the heavy rain and severe threat will set up later today into tonight. Along and south of the boundary, good instability will develop through this afternoon. A weak mid level short wave will move east across the Ohio Valley this afternoon and this may help initiate convection along the boundary. With good shear profiles along the boundary, severe storms with some rotators would be possible later this afternoon into this evening along and south of the boundary with training storms and potential flash flooding too. Farther to the north of the boundary, the storms will be more elevated, leading to primarily a hail threat heading into this evening. The synoptic models are generally farther north than the higher-res cams, with the last several runs of the HRRR keeping the focus generally south of our FA. It does appear the the highest severe threat will be south of the Ohio River, possibly over into far south central Ohio. This is also the area that would seem most prone to flash flooding but with the synoptic models much farther north with their swath of heavy rain later tonight, there remains quite a bit of uncertainty as to where the heaviest rain threat will be. We may eventually need a flash flood watch across parts of the area but prefer to see what the 12Z runs show to see if the flood threat can be more fine tuned. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Warm front nearly parallel to the upper flow will remain in the region tonight, lifting to Northwest Ohio. As isentropic lift intensifies under a strengthening upper jet, showers will become widespread in northwestern locations, while showers will be much less prevalent in the southeast farther from the boundary. Convective development will be enhanced by ample short wave energy and moisture advection traveling along the slow moving boundary. Thunderstorms will be possible in a zone of elevated CAPE near the front, and some storms may reach severe limits. Models indicate favorable wind shear profiles above an inversion layer that suggest large hail as the main threat. Showers and a few thunderstorms will continue mainly across northern locations on Saturday. Activity should show a diminishing trend by Saturday evening when the frontal forcing is forecast to lift toward Lake Erie. With the area mainly in the warm sector, temperatures will exhibit a warming trend. Highs will range from the upper 60s north, up to the mid 80s south. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Warm and moist southwest flow aloft will lead to an active weather pattern this weekend into early next week. Surface warm front to lift north through ILN/s FA Saturday night. Best forcing associated with low level jet/instability and moisture to our west. Therefore, will limit pops to chance category with the best chance northwest. Upper level low to develop over the Central Plains and then lift northeast into the Upper MS Vly Monday. On Sunday the best forcing and lift to our west with ILN/s FA in the warm sector. Will limit pops to chance across the western counties. Temperatures look to be 10 to 15 degrees above normal, with highs Sunday ranging from 80 northwest to the upper 80s southeast. Model solutions generally similar with strong cold front pushing east into ILN/s western counties by 12Z Monday and then sweeping east across the FA early. Due to strong front expect widespread convection to develop but instability is marginal. PW/s increase to above 1.5 inches, so heavy rain rates will be likely but precipitation will be progressive with front east of ILN/s by early afternoon. 850 mb winds of 45-50 kts will persist in the wake of the front in CAA pattern. Momentum transfer technique suggest surface wind gusts of 40 mph likely. Will continue to highlight this threat in the HWO product. Temperatures will be turn cooler with highs Monday from the mid 60s west to the mid 70s east. Deep upper level low to track ene through the Great Lakes Monday into Tuesday. Will keep chance pops of a shower across the north into early Tuesday. Temperatures will be a little below normal, with highs ranging from near 60 northwest to the upper 60s southeast. Mid/upper level flow backs with moisture increasing Wednesday acrs the far south and then across the entire FA Thursday. Model solutions differ on moisture placement Thursday with GFS keeping main moisture east. Have favored a Canadian/Ecmwf blend with best pops in the east Thursday but spreading pcpn chances across the entire area. Wednesday`s highs look to range from the lower 60s northwest to the upper 60s southeast. Thursday looks even cooler with highs of 60 to 65. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... Period starts dry under weak high pressure giving mainly mid and high clouds. BR will reduce visibility at LCK early in the forecast, with MVFR ceilings at LCK and CMH. Once early morning BR and low clouds dissipate, conditions will then deteriorate slowly as a warm front develops. Clouds will thicken and lower while ceilings remain VFR through the afternoon and evening, and showers may occur by evening at western sites in increasing moisture and lift associated with the warm front. MVFR conditions may eventually accompany the showers late in the forecast period as the boundary layer nears saturation. Added VCTS to all TAFs, with further refinement likely in later forecasts. Surface winds from the southeast will stay under 10 knots during the early part of the forecast. Speeds around 10 knots out of the south are expected later in the forecast with the showers. Wind shear is expected to develop for a few hours late in the forecast. OUTLOOK...MVFR ceilings and visibilities with a chance of thunderstorms are possible Saturday, Sunday night and Monday. Wind gusts to 35 kt possible Sunday into Tuesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...JGL SHORT TERM...Coniglio LONG TERM...AR AVIATION...Coniglio

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