textproduct: Wilmington

WHAT HAS CHANGED

- Updated information and timing regarding Tuesday's severe weather threat. - Minor updates to details on episodic storm chances through the remainder of the week and this weekend's strong cold front.

KEY MESSAGES

1) A few strong to severe thunderstorms are possible Tuesday, primarily across west-central Ohio, with near record high temperatures possible.

2) Well above normal temperatures are expected through the rest of the week. Episodic shower and thunderstorm chances continue.

3) Strong cold front moves through this weekend, bringing cooler temperatures Sunday and Monday.

DISCUSSION

KEY MESSAGE 1)

A frontal boundary will stall out just to our northwest, providing the focus for multiple disturbances to travel along today through Tuesday. The first disturbance moves through Tuesday morning. Ongoing decaying convection from the overnight is expected to progress east/southeast into the ILN FA after daybreak on Tuesday. There is still high uncertainty on how things will progress as early morning storm maintenance isn't ideal due to lack of SB instability and paltry LL lapse rates. There is a chance that these factors overwhelm the LLJ (mentioned in a moment) and storms dissipate.

However, a 40 knot 700mb LLJ stretched from southwest IN through north central OH may do enough for storm maintenance that we could see some convection re-strengthening or even re-developing by the time it reaches the far northwestern portions of ILN by noon-ish (Mercer/Auglaize counties). If storms can survive through noon, by then, SB instability and lapse rates across our CWA should rebound enough (combined with the strong wind profile) to support some stronger, more organized, storms particularly northwest of I-71. Timing would be between noon and 9PM or so. Main hazards on the table would be damaging winds and large hail.

Meanwhile, all this uncertainty with storm development (or lack thereof) will have a big impact on temperatures Tuesday. If storms hold together and blow through the region during the afternoon hours, this would inhibit how warm we get and therefore, probably keep us from reaching temperature records. However, if storms struggle to hold together or if timing is pushed later, then we may be able to tickle high temperature records thanks to the strong WAA regime across our area.

Tuesday the current records are CVG 84F (1887), CMH 86F (1883), and DAY 82F (1931,1941). Current forecasted highs for Tuesday are CVG 82F, CMH 82F, DAY 83F.

As we head into Tuesday evening, a handful of CAMs pull some additional blowoff convection into our northern counties Tuesday overnight into Wednesday. Confidence on this is rather low at the moment, since any afternoon convection would likely turn over the environment and overnight timing would indicate a dissipation of SB instability and LL lapse rates. Though, cannot rule out some blowoff rain showers during the overnight hours along and north of I-70.

KEY MESSAGE 2) The broader synoptic setup remains the same going into Wednesday and Thursday. The mid-level ridge will remain in place and will continue to support warm/moist air moving in from the southwest.

CAMs once again suggest thunderstorm development along that frontal boundary to our northwest, with decaying storms progressing into our northern counties Wednesday daytime hours. The more robust severe threat looks to remain well to our northwest, though cannot rule out a stronger storm with damaging winds. However, with training storms and showers, cannot rule out an isolated area or two having some runoff or ponding issues with repeated rounds of rainfall, especially in west central Ohio.

Wednesday night into Thursday, a cold front finally pulls through our area. This will result in drier conditions Thursday night and Friday.

KEY MESSAGE 3) A strong trough digs into the Midwest and Great Lakes region at the end of the work week into the weekend. A strong cold front will pull through the region on Saturday bringing renewed chances for showers and thunderstorms. Strong CAA behind this front will bring much cooler air to the region, with 850mb temps dropping 20 to 25 C in 24 hours. Still a bit early to determine finer details, but early guidance suggests a return to temperatures in the 30s on Sunday night.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

VFR conditions remain in place through the overnight hours into Tuesday. A low level jet in place will keep LLWS in the TAFs through the remainder of the overnight hours.

After sunrise, LLWS decreases as surface winds increase. Southwest winds around 15 knots will periodically gust to 30 knots throughout the day on Tuesday. Surface winds decrease by Tuesday evening, though will remain out of the southwest as we head into the overnight. With surface winds decreasing, we once again need to introduce LLWS as the LLJ remains cranking aloft.

Now the tricky part... a handful of hi-res guidance suggests development of showers/storms Tuesday afternoon (16z through 00Z or so) as blowoff convection from our northwest moves into our area. Confidence on storm development is medium right now. Have hedged bets toward a short period of storms by incorporating PROB30s and TEMPO -TSRAs and MVFR conditions into all sites throughout the afternoon hours. However, be prepared for additional tweaks to timing as we see how things evolve.

OUTLOOK...MVFR conditions and thunderstorms possible at times through Wednesday.

ILN WATCHES/WARNINGS/ADVISORIES

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