Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 181751 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 151 PM EDT Mon Sep 18 2017 .SYNOPSIS... A weak cold front will move into Ohio today, bringing a chance of showers and thunderstorms. Showers and thunderstorms will still be possible Tuesday and Wednesday when the front is forecast to stall over the region. Dry weather is expected Thursday with the return of high pressure. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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18.12Z KILN RAOB sampled a modestly moist airmass for the season /85th percentile - 1.39"/ with weak mid/upper tropospheric lapse amidst very weak flows. This is representative of the airmass within a larger scale mid/upper tropospheric ridge over the eastern U.S. downstream of developing/deep wrn CONUS troughing. Tail end of weak shortwave trough in IND/OH is slowing down as it continues to struggle to exist within the larger scale ridge, and surface cold front is rapidly undergoing frontolysis this morning as result. However, weakly diffluent flow in the mid/upper levels of the troposphere, and remnant kinematic forcing of the shortwave continues to drive elevated/high based showers in a band from NW Ohio into scntl IND. Very few automated gauges have reported any measurable rain in ecntl IND/wcntl OH thus far...just a couple in Darke County and only a hundredth or two. However, a more solid area of rain is approaching Fayette/Wayne/Franklin Counties as of 14Z -- but even this area is slowly eroding on the leading edge and overall radar reflectivity has been trending downward. For the rest of the day...expect a large difference in weather across the ILN forecast area. In the Scioto Valley of central/southeast OH, expect a fair amount of sunshine amidst low precipitable water and warm afternoon high temperatures, as mid clouds slowly work into the area. Further west, expect current rain showers to slowly decrease in coverage/intensity through early afternoon, eroding as they approach I-75. However, mid cloud will remain in pretty solid fashion. As peak heating/destabilization take place by mid/late afternoon, a few showers/storms will redevelop - likely on differential heating zones left by morning showers. Shear is expected to remain very weak (effective shear < 15kts) and MUCAPE to 800 J/kg will likely allow for a few slow moving storms to develop. Locally heavy rain the primary impacts. Decreased temps a bit in heavily clouded areas for the afternoon - and tweaked rain chances based on latest CAMS and current radar.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... As the weak front moves slowly across Ohio early tonight, it will outrun much of its mid level support and moisture. This should allow a lull in shower activity through around Midnight. For late tonight and Tuesday, a better chance for showers and thunderstorms will return due to instability under a mid level short wave arriving from the west and interacting with the nearly stationary boundary. Because of greater convergence and lift that is expected along the section of the front extending into Western Ohio, it appears that western locations will have a higher chance for precip. Above normal temperatures will persist, with highs reaching the lower 80s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Amplified flow pattern with a mean trof over the west and a ridge over the Great Lakes. Weak shortwave to undercut the ridge and drop southeast through the Ohio Valley at mid week. This shortwave combined with marginal instability will lead to a chance of showers and thunderstorms Wednesday. The best chance will occur over the southwest and end during the afternoon as the s/w passes south. The mid level ridge to strengthen over the Great Lakes late in the week into next weekend. This ridge will provide subsidence, dry weather and warm temperatures. Generally expect highs in the lower and middle 80s through the long term forecast period. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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Mainly VFR conditions are expected across the TAF sites through the period, though there is some uncertainty on potential MVFR ceilings and/or visibility later tonight with some light fog, and then with showers on Tuesday morning. Radar has quieted down over the past few hours with most showers dissipating. A sct-bkn mid deck exists early this afternoon and a few-sct cumulus deck will develop through peak heating. A weak front in the area and differential heating boundaries will likely spark mid-late afternoon showers and a few thunderstorms, most likely near DAY/CVG between 20Z and 02Z. Some of these may linger through the night especially near/north of KDAY. Uncertainty rises later in the night with any fog formation potential. Expect a fair amount of clouds to persist through the night as shortwave trough approaches. If clouds end up less than forecast, visibilities may be lower with more valley fog. Right now playing less restrictions to visibility and more clouds, but this will need to be watched. Expect showers to develop/move across the area Tuesday morning, but rates are expected to be light with minimal impacts to aviation. OUTLOOK...No significant weather is expected at this time.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Binau SHORT TERM...Coniglio LONG TERM...AR AVIATION...Binau

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