Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 280621 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 221 AM EDT THU JUL 28 2016 .SYNOPSIS... A stalled frontal boundary near the Ohio River will provide a chance for scattered showers and thunderstorms through this evening. A wave of low pressure traveling along the front will bring an increased likelihood for showers and thunderstorms Thursday into Friday. Unsettled weather will continue into the weekend as several disturbances aloft interact with a persistently moist and unstable airmass. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Mid/high level clouds continue to stream northward into area as convection has fired along and south of a weak stationary front oriented west to east across KY and extreme southern Ohio. Mid level energy will lift northeast into Ohio Valley late tonight, allowing for moisture to surge northward as frontal boundary begins to pivot northward as a warm front. As this occurs, shower and thunderstorm activity will move ENE into southern parts of FA around and after 06z. Expect that with limited instby across northern half of FA, any thunderstorm activity should be constrained to far south parts of area. With high PWATs forecast to be around/in excess of 2 inches, have continued Flash Flood Watch for southeastern parts of FA, and have expanded watch to include 5 additional Kentucky counties. Although activity tonight will be developing in a moist environment, it appears it should be fairly progressive, helping limit the potential for flash flooding in the near term. Forecast lows are still on track for tonight, with upper 60s in the north and lower 70s in the south. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... Main concern on Thursday will be a higher potential for some flash flooding across mainly south-central Ohio and northeast Kentucky as a potent shortwave crosses the ILN CWA and interacts with a very moist airmass. This shortwave energy will develop a couple weak surface lows that will lift through eastern KY into south- central OH in a moisture rich environment with PWATs of 2 to 2.2 inches (2-3 sigma above normal for this time of year). Warm cloud depths will be >4km and a modest LLJ will lead to favorable moisture transport across our southeast, though conditions will be most favorable just outside of the ILN CWA. Given bulk shear vectors from the southwest, do expect potential for training cells over southern Ohio and northern KY. Synoptic models are in pretty good agreement with the axis of heaviest precip setting up over our southeast, so have issued a flash flood watch for this area. At this time expect 1.5 to 2 inches of rainfall within the watch area with locally higher amounts possible. Later shifts will have to monitor whether the better forcing and axis of heaviest precip may shift further west, though. While 0-6km wind shear across our south will range from 25-35 knots, forecast soundings show a nearly saturated column through the mid levels with tall skinny CAPE <1000 J/kg. Thus, severe potential should be limited. Precip chances will decrease Thursday night as the best forcing pushes east. Cloud cover and rain will keep temperatures down across our southeast, where highs will likely struggle to reach 80. It will be warmer northwest of I-71 where temperatures will climb into the low to mid 80s. Lows Thursday night will be in the mid to upper 60s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... The long term will start with a series of upper level disturbances moving across the area along with a front stalled out. This will help to keep the chance of rain in the forecast almost through the entire extended until Tuesday when weak mid-level ridging moves into the region. Looking more into the details, Friday will open up with a shortwave moving across the region and the leftover frontal boundary from earlier in the week still across the area. Upper level lift is sufficient with weak PVA moving across and moisture values remain above average for this time of year with PWATs forecasted to be around 1.70". Instability is also present with ML CAPE values around 500 J/kg. As the shortwave exits Friday PoPs will slowly taper off due to weak subsidence behind the wave. Saturday through Sunday another weak shortwave trough will remain in close proximity to the area with a surface front located across the CWA. This will help to bring the chance of rain right back to the area. Given the weak upper level trough quickly pulling east the cold front stalling across the area seems likely. Given the chance of showers and thunderstorms during the day have kept high temperatures near climo. Monday into Tuesday as the shortwave trough exits weak mid-level ridging will then build overhead as mid-level high pressure builds over the central United States. There still remains timing differences on when the high will build and how far it will build east. For now have just trended PoPs down. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... Upper level trof over the lower Mississippi valley will lift northeast today. As a result, a surface wave of low pressure will develop and track northeast through the Ohio valley this afternoon. A surge of tropical moisture overspread the region ahead of the sfc wave as the weak sfc boundary pivots north into the area. Showers and thunderstorms will overspread the southern TAF sites early this morning. The preciptiation activity will increase in coverage after 12z, with best coverage expected along and south of the I-71 corridor. Deepest moisture to shift east of TAF sites this aftn, so expect pcpn to become widely scattered. Due lagging upper level support and unstbl airmass have kept VCTS until early evening. OUTLOOK...Thunderstorms likely Thursday night through Saturday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Flash Flood Watch through Friday morning for OHZ079-081-082- 088. KY...Flash Flood Watch through Friday morning for KYZ089-090- 094>100. IN...None. && $$ SYNOPSIS...Kurz NEAR TERM...Coniglio/Kurz/Sites SHORT TERM...Kurz LONG TERM...JDR AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.