textproduct: Wilmington

SYNOPSIS

High pressure extending across the region will slowly shift east on Sunday, with a chance of a late day thunderstorms ahead of an approaching cold front. This weak cold front will drop into the area on Monday and then dissipate into midweek.

NEAR TERM /THROUGH SUNDAY/

Area continues to be dominated by mid level ridging, with surface high centered over western VA slowly pulling east. Light SW flow will wane again overnight, allowing for some valley fog mainly in NE KY and areas of the Scioto/Hocking/Licking valleys. Muggy overnight lows near 70.

SHORT TERM /SUNDAY NIGHT/

A short wave and associated cold front will drop from the western Great Lakes and approach the NW forecast area, mainly near and NW of Dayton. So there is expectation of a few more cumulus clouds on Sunday. Southern Ohio, SE Indiana and northern Kentucky have the best chance for some spotty locations to reach 100 heat index values where clouds will be a little more sparse and higher surface dewpoints linger. CAMs have been coming in with a chance for scattered to widely scattered late afternoon and early evening thunderstorms, and as mentioned in previous discussion, some models hinting at mid level energy and increased moisture working in from the south from the activity centered over the SE CONUS. If this pattern persists, may have to bring in a chance for Sunday afternoon activity further south into the Tri State.

For Sunday night, while convective activity ahead of the approaching cold front will wane with the loss of daytime instability, still some potential for isolated showers/storms in West central Ohio through eastern Indiana. Overnight lows a little warmer into the lower 70s.

LONG TERM /MONDAY THROUGH SATURDAY/

There are still some differences in how wet the week will be but in the least, rainfall chances are likely to persist throughout the entire long term period.

Temperatures start off hot on Monday, especially as moisture pools against the cold front dropping into the area. Thunderstorms are expected throughout the afternoon and evening with downburst and locally heavy rainfall potential returning to the area. Mean flow of 10-15 knots should keep thunderstorms moving northeast over time, but backbuilding setups will likely result in localized flash flooding.

Tuesday, confidence begins to decrease in the overall pattern evolution with the ECMWF ensemble still faster to push moisture southward, limiting shower and thunderstorm chances to along and south of the Ohio River. The GEFS is a bit slower, keeping rainfall chances along and south of I-70. NBM splits the difference with the highest PoPs across the southern half of the area.

Additional differences continue Wednesday with the GEFS faster with the next system and the ECMWF ensemble still quite dry. There will likely be a diurnal component to the coverage in showers/thunderstorms Wednesday, but the overall forecast is likely to change (higher or lower PoPs) over the coming days.

By Thursday, a deeper trough dips through the Great Lakes, increasing PoPs over the entire area. Depending on the speed at which the front moves through, there will still be a lingering threat for additional thunderstorms Friday, especially across northern Kentucky and southern Ohio.

Ensemble guidance diverges again for Saturday with the GEFS bringing a stronger trough into the Great Lakes (wetter solution for local area) and ECMWF ensemble dipping it into the central Plains (drier solution for the local area).

Overall, Monday is expected to be the warmest day of the week with the rest of the week influenced by clouds and precipitation. If the drier solution works out for Tuesday and Wednesday, less humid conditions may be experienced for a large portion of the area.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions are expected to prevail through the period, with VFR Cu dissipating early in the TAF period, with a little more Cu by the afternoon once again with the approach of the weak cold front.

Light/VRB/calm winds are expected through daybreak, which will support the development of some river valley BR/FG once again. As such, expect MVFR, to possibly IFR, VSBY restrictions at KLUK in the several hours around sunrise. Thereafter, SW winds will increase to around 10kts by the afternoon.

There is a signal for a few ISO SHRA/TSRA to develop within a narrow corridor from near KCVG/KLUK to KILN and potentially up toward KCMH/KLCK as well, particularly between 18z-22z. Have added a PROB30 in the fcst for these sites given this signal, although uncertainties exist regarding exact location and coverage of activity. ISO activity should spread to the NE near/E of the I-71 corridor through mid/late afternoon before dissipating toward/beyond 00z Monday.

OUTLOOK...Thunderstorms are possible Monday evening, Tuesday, and Wednesday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Air Quality Alert until midnight EDT tonight for OHZ046-055-056-065- 070-071-077-078. KY...Air Quality Alert until midnight EDT tonight for KYZ091>093. IN...Air Quality Alert until midnight EDT tonight for INZ074.