textproduct: Wilmington

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Showers and thunderstorms will occur ahead of a cold front that will move through the region Friday evening.

2) More showers and storms will occur late Monday into Monday night ahead of the next cold front.

DISCUSSION

KEY MESSAGE 1) Some isolated showers/storms will be possible very briefly across portions of central OH this afternoon within a narrow WNW-to-ESE corridor of low-end SB-instby, with a drying BL with deep mixing further to the S entrenched across most of the ILN FA. The steering- layer flow will push this activity to the NE and out of the ILN FA by late afternoon, offering only a 2-3 hour window (i.e. about 19z-22z) of potential ISO activity focused from near Union to Licking Cos OH (and points further to the NE across ern OH).

Midlevel ridging will traverse the region tonight into early Friday ahead of a weak system which will progress E across the region Friday evening into Friday. S/W energy will break off the srn flank of a closed low centered over srn Canada, migrating into the OH Vly by late afternoon into early evening. This will provide a focus for some forcing amidst about 500-1000 J/kg MLCAPE, with the reservoir of better LL moisture/instby residing primarily near/W of I-75. Further to the E of this corridor, sfc dewpoints should mix down into the mid/upper 50s, with the better moisture (sfc dewpoints around 60 degrees) evolving into the wrn third of the ILN FA after 18z. Deep- layer shear should be relatively weak, primarily on the order of about 20kts, so storms should be relatively disorganized, perhaps developing into several loosely-organized linear clusters by about 21z. The overall severe potential remains low, although some gusty winds and small hail will again be possible with this activity. Isolated damaging winds and/or large hail will be the primary threats with the strongest cores, although this potential will drop off rather abruptly with eastward extent by about 03z. Do think that the MRGL SWODY2 is well-placed and covers with overall threat of strong storms (with ISO severe) Friday evening into early overnight.

The sfc front associated with this feature will become increasingly ill-defined with eastward extent late Friday night into early Saturday, with drier air attempting to filter into NW parts of the ILN FA before the boundary essentially washes out in the ILN FA through the daytime Saturday. Certainly there will be /slightly/ cooler/drier air that will settle into the area through the daytime, but parts of the ILN FA (especially near/S of the OH Rvr) will struggle to have the LL moisture scoured out completely until LL flow becomes more N/NE by Saturday night.

Highs on Friday will be unseasonably warm ahead of the approaching weak front, topping out in the lower to mid 80s. Slightly cooler conditions are expected for Saturday/Sunday, with lows in the 50s and highs in the mid 70s.

KEY MESSAGE 2) Midlevel ridging will build into the OH Vly Saturday into Sunday before a potent system moves into the mid MS Rvr Vly and OH Vly for Monday/Monday night. While the specifics of this system are still to be determined, the pattern continues to highlight the potential for severe storms across at least portions of the OH Vly, with highest probabilities currently favored W of the ILN FA.

Ensemble and various AI guidance suggests a potent S/W digging into the mid MS Rvr Vly by Monday afternoon, with an expanding warm sector out ahead of it into the ILN FA. This strengthening system will induce a deepening sfc low, which is fcst to migrate from MO into IA/MN through the daytime Monday, with an attendant cold front flanked to the S. LL and deep-layer flow fields will increase accordingly from MO/wrn KY to IN/OH, setting up an environment characterized by robust shear and moderate instby in the mid MS Rvr Vly and wrn/srn OH Vly. The highest spatial/temporal overlap of a highly-sheared and unstable environment looks to be centered to the W of the ILN FA by midday, particularly across ern MO into srn IL/IN and wrn KY/TN, with slightly less instby progressively east of this focused area.

There are still some uncertainties regarding location, timing, and overall severity of activity with eastward extent Monday evening into early Monday night. Based on current guidance, it looks like most of the ILN FA will remain dry through much of the daytime Monday, with the best coverage of storms expected late evening into early overnight. With this, there are questions about instability availability into the nighttime, with the details of this still yet to come into focus. Nevertheless, there should be strong forcing and widespread coverage of showers/storms to promote some heavy rain/localized flooding threat as well, primarily Monday night.

Monday evening/night will continued to be monitored closely for impacts locally. Additional updates will be provided in the coming days.

AVIATION /18Z THURSDAY THROUGH MONDAY/

VFR conditions will prevail through the period, with high-based Cu developing through this afternoon, particularly for central OH sites of KCMH/KLCK. These clouds will diminish after 00Z. Winds will become southwest, increasing to 10 to 15kts by this afternoon. Winds will back to the south and become light again after 00z before increasing out of the SW once again by late in the period.

Some SCT SHRA/TSRA may impact KCVG near 00z Saturday, with several broken clusters expected near wrn sites of KCVG/KLUK/KDAY by this time.

OUTLOOK....Thunderstorms possible Friday into Friday night. MVFR ceilings are possible Friday night into Saturday morning. Thunderstorms possible again Monday evening.

ILN WATCHES/WARNINGS/ADVISORIES

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