076 FXUS61 KILN 210616 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 216 AM EDT Sat Aug 21 2021 .SYNOPSIS... Weak high pressure will lead to patchy early morning fog with The threat for showers and thunderstorms is forecast to be isolated today under this weak high pressure. A disturbance will interact with an unstable airmass to keep a low chance for precipitation Sunday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Surface high pressure remains in place over the upper Ohio Valley, with weak northerly flow over the ILN forecast area. Just a few showers are persisting at this hour, with dry conditions expected soon, and mostly clear skies expected overnight. No significant changes were made to the forecast overnight, which includes the potential for fog. Compared to yesterday, dewpoints are a little lower, there is much less of a signal for widespread fog on recent HRRR runs and the 21Z SREF probabilities. This suggests fog will largely be more limited to river valleys tonight, with lighter visibility restrictions elsewhere. Previous discussion > Weak high pressure is slowly drifting to the east with widely scattered showers and thunderstorms occurring over west-central Ohio and the Miami River Valley. Expecting this activity to linger into the early evening before weakening. Mostly clear skies are forecast once again tonight. Weak high pressure will be further east of the region overnight so have highlighted the best chances for fog across the Scioto and Ohio River Valleys. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... Fog impacts will improve by 9-10 am with the longest duration expected for the lower Scioto Valley and northern Kentucky counties. For the afternoon, the local area is between TC Henri off the Mid-Atlantic coast and a weak area of ascent the west. Leaned drier than previous forecast package with temperatures in the upper 80s and perhaps into the lower 90s. Fog may once again be an issue Saturday morning with the lowest visibility in local valleys/river valleys. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Weak front will move into the area on Sunday afternoon. There may be enough forcing to generate some showers and thunderstorms in western counties. Any activity will dissipate with loss of heating. The boundary may make it further east overnight but continue to weaken and eventually wash out on Monday. Mid level ridge centered over the southern Plains will extend into the Ohio Valley Monday and Tuesday. The eastern edge of the ridge will then erode as weak troughing occurs along the Appalachians. This will allow disturbances moving over the top of the ridge to drop across the region. As a result there will be a chance of showers and thunderstorms for mid to late week. Above normal temperatures will persist, although readings may start to moderate by the end of the period. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... Weak surface high pressure will offer light winds and mainly clear skies overnight. Surface dewpoints are a couple of degrees cooler than yesterday. These conditions will lead to patchy fog development. Have MVFR conditions at KCVG, KDAY and KCMH with IFR restrictions at KLUK and KILN. Visibilities should improve to VFR by 14Z. Expect only scattered cumulus clouds during the afternoon. Winds will be light through the TAF period, generally 5 knots or less. OUTLOOK...Thunderstorms are possible on Sunday afternoon, and again on Tuesday and Wednesday afternoon. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...McGinnis NEAR TERM...Hatzos/McGinnis SHORT TERM...McGinnis LONG TERM... AVIATION...AR