Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 161741 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 141 PM EDT Wed Aug 16 2017 .SYNOPSIS... A weak frontal boundary will stall across the area this morning, offering a threat for isolated showers. After some morning fog, a disturbance approaching from the southwest will combine with the stalled boundary to produce a threat of showers and storms this afternoon and night. A stronger frontal system will swing through the Ohio Valley on Thursday afternoon and evening bringing a higher chance of more widespread shower and thunderstorm activity. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... With showers generally dissipating across the area earlier this morning, mostly clear skies have been left in place, outside of the southern sections of the CWA. Though there is not a significant gradient in surface dewpoints, a gradual advection of moisture a little further aloft is expected as the day progresses, which should add clouds (from current stratocumulus to additional cumulus development) to the region over the next few hours. Though MLCAPE values may increase into the 500-1000 J/kg range today, absent any notable low-level forcing, there should not be significant coverage of precipitation -- with the best chances near the greater moisture in the southern and southwestern sections of the CWA. One change for this forecast is a 20-percent chance of showers added to the entire CWA by mid-afternoon, with the atmosphere appearing favorable for a few very light showers to develop just about anywhere. Nonetheless, most locations should still remain dry. Made some near-term decreases in sky grids, but temperatures appear to be on track with the previous numbers. Previous discussion > A few showers continue to linger across central Ohio in the vicinity of weak frontal boundary. Due to lack of upper level support with mid level ridge over the region, expect this activity to continue to weaken early this morning. Mostly clear skies, light winds and moist low level has lead to patchy fog across ILN/s area. This shallow fog will quickly improve with sunrise. Shortwave ridging to move across the Ohio Valley downstream from wave moving across the plains today. The morning and first part of the afternoon expected to be dry. Moisture increases with boundary layer cape values of 1000-1500 j/kg into the southwest this afternoon. Have thunderstorm chances developing into the southwest with increasing chances from southwest to northeast through the later afternoon hours. Temperatures will continue above normal with todays highs similar to yesterday in the mid and upper 80s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Mid level ridge to shift east with flow backing as s/w tracking into the MS VLY tonight. Thunderstorm chances will increase, especially over the nw counties as low level convergence/warm front develops. Have continued high chance pops late tonight. With increasing moisture and clouds temperatures will be mild tonight with lows generally in the lower 70s. Ongoing storms to start Thursday especially invof of the warm front. Moisture increases as 30-35 kt southwesterly low level jet comes into play with precipitable water values increasing to near 2 inches. Boundary layer cape values of 2000-2500 j/kg expected to develop across the area Thursday in the warm sector. Bulk shear of 35-40 kts across the southern Great Lakes along with this instby will support convective development with some organized clusters. Isolated damaging wind gusts will be possible along with the potential for heavy rain and local flooding. will mention this threat in the HWO product. Warm temperatures to continue with Thursdays highs from the lower 80s northwest to the upper 80s southeast. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Cold front will be moving east Thursday night. Showers and thunderstorms are likely to be ongoing Thursday evening, diminishing during the overnight hours as daytime heating dwindles and frontal forcing departs. Some thunderstorms may contain strong wind gusts early Thursday night, and localized flooding will be possible in an atmosphere containing about 2 inches precipitable water. A few thunderstorms may even linger on Friday, mainly over eastern locations where greater residual instability and moisture will be evident. After a weak ridge brings a brief dry period Friday night, a disturbance traveling across the Great Lakes may trigger a few thunderstorms during peak heating on Saturday. Dry weather is indicated for Sunday when a large area of high pressure is forecast to be centered to the east. Isolated thunderstorms cannot be ruled out for Monday in the increasingly humid return flow around the high. A better chance for thunderstorms will exist on Tuesday due to a strong short wave and cold front. High temperatures starting near normal in the low to mid 80s will boosted by warm advection to the mid and upper 80s by the end of the long term. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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Isolated/scattered and disorganized showers are developing over the region today, with a slight chance of a thunderstorm in the Cincinnati area this afternoon. It still appears this will be too isolated to include specifically in any of the TAFs, outside of running a VCSH at KCVG/KLUK. With mid-level clouds moving into the region overnight, it is unclear how much fog will be able to form. However, given the past few nights and the abundant low-level moisture, some MVFR visibilities appear possible by morning. Storms will become more widespread tomorrow afternoon, though the most likely timing will be after the end of the TAF period. Nonetheless, some rain or storms may be posible in the late morning and early afternoon. Widespread MVFR or lower conditions are not expected as of now. Wind gusts of 15-20 knots will be possible tomorrow afternoon. OUTLOOK...Thunderstorms are possible Thursday afternoon and night.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau/AR NEAR TERM...Hatzos/AR SHORT TERM...AR LONG TERM...Coniglio AVIATION...Hatzos

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