textproduct: Wilmington

WHAT HAS CHANGED

Widespread showers and storms are expected through the daytime as a front slowly drifts south through the local area. A few isolated strong to severe storms may be possible south of I-70 to near the Ohio River this afternoon into early evening.

KEY MESSAGES

1) A cold front will lay out approximately west to east across the local area through the daytime, with a very tight temperature gradient evolving by the afternoon, with 40s and 50s in west-central to central OH and 70s and 80s near/south of the Ohio River.

2) Numerous showers and storms are expected through the daytime as a front slowly drifts south through the local area. A few isolated strong to severe storms cannot be ruled out near the Ohio River this afternoon into early evening.

3) The warm and active weather pattern continues through most of the week, with several rounds of showers and storms expected into the upcoming weekend. A much cooler and drier pattern will return for early next week.

DISCUSSION

KEY MESSAGE 1)

A cold front, oriented approximately west-to-east, will slowly drift S through the ILN FA through the daytime. This boundary will not only provide a focus for shower and storm activity, but also result in a very tight temp gradient by mid afternoon. North of the front, where expansive low clouds and NE sfc flow will become established, temps in the 40s and 50s are expected by mid afternoon. S of the front, closer to the OH Rvr and points further to the S into N/NE KY, some brief peeks of sunshine along with SW sfc flow will help temps reach into the upper 70s to near 80 degrees prior to convective influences.

Key Message 2)

The front will provide a focus for numerous showers/storms during the daytime, with several clusters of convection expected to develop and migrate E through the srn half of the local area by late morning through early evening. Some diurnally-enhanced instby will develop into the area by noon, stretching from SE IN through south-central OH from approximately Franklin Co IN to Hocking Co OH and points further S. The instby/moisture/theta-e gradient will provide a focus for several rounds of loosely-organized multicell clusters of storms by early to mid afternoon, with moderate MLCAPE on the order of 1000+ J/kg in these areas. Effective bulk shear on the order of about 30kts will be sufficient to promote the development of multi-cell clusters or mini linear segments, the strongest of which could produce gusty winds and /very/ isolated damaging winds. The greatest threat with this activity will be gusty winds, especially with steep LL lapse rates S of the sfc front. However, the lack of substantial shear and relative weak forcing will inhibit the overall storm organization potential, leading to an environment that may be capable of isolated wind damage and small hail, but probably not much more than that. This is certainly a marginal potential for severe storms that will evolve strictly near/S of the front in the areas described. The greatest coverage of storms will be from around noon to about 8 PM before coverage becomes more isolated in N/NE KY by mid/late evening.

ISO SHRA will linger near the front as it begins to pivot back N rather abruptly by/after midnight, clearing the ILN FA around daybreak Thursday. This will usher in much warmer/moiusture-rich air back into the area, with a non-diurnal temp trace expected tonight with the warm front surging back N late in the night.

Key Message 3)

A more-amplified S/W will pivot into the mid MS Rvr Vly late tonight into the day Thursday, with downstream ridging expanding in response to the approach of this feature. The ILN FA will be positioned squarely in the expanding warm-sector, with the LL boundary surging well to the N of the local area during the afternoon.

With the surge of moisture/warmth north across the area by Thursday afternoon, suppose that a few spotty SHRA/TSRA cannot be ruled out as the cap will be relatively shallow. However, there isn't much instby or forcing at all to initiate this activity until late evening, so confidence on coverage of activity during the afternoon is quite low. Shower/storm activity will likely increase into far wrn parts of the local area early Thursday night, with the S/W gradually being forced over the crest of the ridge centered off the Carolina coast. This suggests that the forcing should decrease a bit later into the night, so there are uncertainties regarding the maintenance of convective coverage/intensity further E into the local area into Friday morning. The best chance for showers/storms Thursday night will be near/W of I-71.

Another system will impact the region with additional showers/storms Saturday into Saturday night before drier conditions return by Sunday. Above normal temps are likely Thursday through Saturday, with highs in the 80s and lows in the 50s and 60s during this stretch before much cooler air settles back in Sunday through early next week. Some patchy frost may be possible at times early next week, but the expanse of this will ultimately be dictated based on subtle changes in cloud cover and winds.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

A cold front will move into the area through the day, pushing through area TAF sites into the afternoon. The front may stall for a bit during the afternoon near KILN as SW surface winds resist the southerly push. The tight front complicates the overall wind forecast as SW winds will turn to out of the NE following the FROPA for nrn sites of KDAY/KCMH/KLCK within the first hour or two of the TAF period. Winds will generally be fairly light near the front itself, but out of the SW at about 10kts ahead of the boundary.

The front will be very close to KILN by about 18z, with a west-to- east corridor of SHRA/TSRA activity expected to develop near the front by the afternoon. This activity will be most widespread for KILN/KCVG/KLUK between about 16z-22z, but some SHRA is still expected for KDAY/KCMH/KLCK. ISO activity may linger well past 00z as the front crawls further S into the evening. The front will begin to abruptly pivot back N between 06z-12z, with ISO SHRA expected as this occurs from SW to NE through the predawn hours.

MVFR/IFR CIGs are developing in the post-frontal environment, persisting for northern TAF sites through the entirety of the day. These CIGs will overspread from N to S through the daytime, with some MVFR VSBY also likely behind the front. Given the uncertainty with the timing of the front, MVFR CIGs were included for KCVG/KLUK around/after 00z before going back VFR after 06z as the front begins to surge back N. Clearing skies are expected from S to N by 12z Thursday, with SW winds of 12-15kts, and gusts to around 25kts, expected by the end of the KCVG 30-hr TAF.

OUTLOOK...Periodic thunderstorms with MVFR conditions are possible through Saturday night.

ILN WATCHES/WARNINGS/ADVISORIES

OH...None. KY...None. IN...None.