Area Forecast Discussion
Issued by NWS Wilmington, OH

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867 FXUS61 KILN 261947 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 347 PM 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 AM TUESDAY MORNING/... Shortwave to drop se into the mean trof position over southern lower MI this evening. Marginal instby develops late this afternoon into early evening over west central Ohio. Will continue to allow very low pop chances into the west late in the day. highs again in the lower to mid 70s. Expect this pcpn axis to drop southeast through ILN/s FA tonight and then diminish from the northwest. As marginal cape diminishes with the loss of heating thunder chances diminish so will transition to just showers. Clouds will diminish from the northwest late tonight as surface high pressure begins to nose into the region. Expect cold lows to range from near 50 north to the mid 50s south. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Precipitation could be lingering in the southeast very early Tuesday, but will move off to the southeast. In northwest flow pattern, surface high pressure to build into the region Tuesday. With cold 8H pool over the region expect some shallow high based cumulus clouds to develop. Tuesday will be dry with rather cool highs from the lower 70s northeast to the mid 70s southwest. Surface high pressure to slide east of the region Tuesday night. Diurnally driven cumulus clouds will give way to clear skies early Tuesday evening. Expect cool lows from near 50 northeast to the mid 50s southwest. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... On Wednesday morning, surface high pressure will be centered over West Virginia, with a relatively dry air mass remaining in place across the Ohio Valley region. With heights rising, and southerly flow firmly in place in the low levels, warm advection should be notable -- with a temperature rise to near 80 degrees. As a more progressive pattern begins to set up for Thursday and beyond, mesoscale details will play a significant role in exact timing and placement of precipitation. A frontal zone is expected to set up east-to-west across the southern Great Lakes beginning early Thursday, but despite this, theta-e and wind plots suggest the ILN CWA will remain in the warm sector (a regime of solid deep-layer southwesterly flow) through Saturday afternoon. This will tend to favor convective initiation upstream (north and northwest) of the ILN CWA on Thursday and Friday, with eventual some propagation downstream which should impact the ILN CWA. PoPs have been focused on the northern sections of the CWA, with greater expectations during diurnal or post-diurnal time frames (afternoon through evening / early overnight). A shortwave moving east across Lake Michigan will provide extra support for convection Friday evening, but this too seems likely to not land a direct hit on the ILN CWA. It may take until cold frontal progression on Saturday / Saturday night before chances increase CWA-wide, and PoPs were increased on Saturday to reflect this. Through this period, how much of the CWA remains capped is a question, and mesoscale foci / localized forcing will help decide if storms can develop within the warm sector. With ample instability and at least somewhat favorable deep-layer shear, some heavy rainfall / strong to severe storms could be possible from Thursday through Saturday. Confidence in any specifics will keep this out of the HWO for now. With a clearing push behind the cold front late Saturday, models have trended drier for Sunday, before warm advection begins to bring a chance of precipitation into the area again on Monday. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... Mid level shortwave to drop se into the mean trof position over southern lower MI this evening. A good deal of VFR cumulus clouds around 5000 feet have developed across the TAF sites this afternoon. Marginal instby develops late this afternoon into early evening over west central Ohio. A threat of showers and perhaps an embedded thunderstorm to move across the TAF sites this evening. Due to low expected coverage, and with marginal instability which diminishes, have limited any mention in the TAF forecasts to VCSH. Clouds will diminish with skies clearing out late tonight in as subsidence behind the upper shortwave combines with a building surface high pressure system to the west. Expect continued VFR conditions on Tuesday with only afternoon cumulus clouds developing. WNW winds at 10 to 15 kts with gusts up to 25 kts this afternoon will diminish to less than 10 kts tonight. OUTLOOK...Showers and thunderstorms are possible Thursday and Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR NEAR TERM...AR SHORT TERM...AR LONG TERM...Hatzos AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.