ACUS01 KWNS 111257

SWODY1

SPC AC 111255



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0655 AM CST Wed Nov 11 2026



Valid 111300Z - 121200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF

EASTERN ILLINOIS INTO INDIANA...WESTERN/CENTRAL KENTUCKY...AND

MIDDLE TENNESSEE...



...SUMMARY...

Thunderstorms capable of producing isolated hail, damaging winds,

and perhaps a tornado may occur this afternoon and evening across

parts of eastern Illinois into Indiana, western/central Kentucky,

and middle Tennessee.



...Midwest/Lower Ohio Valley into Middle Tennessee...

Recent water vapor satellite imagery shows a mid-level shortwave

trough digging southeastward over the Upper Midwest towards the mid

MS Valley, with recent elevated thunderstorm development noted over

eastern IA capable of producing small hail (reference ~300 J/kg

MUCAPE in the 12Z observed DVN sounding). A related weak surface low

will develop from southeast IA this morning to the IN vicinity by

late afternoon/early evening. A trailing cold front will continue

advancing east-southeastward across the southern Plains, mid MS

Valley/Mid-South, and lower OH Valley this afternoon and evening.

The main uncertainty and likely limiting factor to severe potential

today remains shallow/limited low-level moisture ahead of the front

across the Midwest/lower OH Valley, where latest surface

observations show dewpoints generally in the 30s to mid 40s.

Somewhat greater low-level moisture associated with a modified

continental polar airmass is present across the southern Plains into

the Ozarks/lower MS Valley. But, west-northwesterly low-level flow

noted in area VWP trends and forecast low-level trajectories suggest

this moisture will struggle to advect northward through the day,

perhaps reaching parts of middle TN/southern KY. Therefore, most

guidance appears a bit moist with boundary-layer dewpoints and

related instability this afternoon, although some mid-level

moistening could occur.



Current expectations are for surface-based thunderstorms to

initially develop over eastern IL by 18-21Z, with additional

development possible with southward extent along/ahead of the front

in western/central KY through the afternoon/early evening as the

boundary layer gradually destabilizes. The combination of weak, but

potentially sufficient, MLCAPE and 30-40 kt of deep-layer shear

oriented largely orthogonal to the surface cold front should support

updraft organization. A mix of clusters and marginal supercells are

expected to evolve and spread quickly eastward while posing an

isolated threat for hail and damaging winds given cold mid-level

temperatures and modestly steepened low-level lapse rates. However,

the lack of greater low-level moisture/stronger instability should

tend to limit the overall severe threat. Modestly enhanced low-level

shear may also support a tornado risk, especially if a supercell can

develop and be sustained. But, tendency for low-level flow to veer

to westerly should reduce effective SRH with time through the late

afternoon/evening. The isolated severe risk should wane this evening

with eastward extent across the lower OH Valley as instability

diminishes with the loss of daytime heating.



...Central/Southern Florida Peninsula...

Isolated to scattered thunderstorms should preferentially form along

the Atlantic Coast sea breeze this afternoon across the

central/southern FL Peninsula. Glancing large-scale ascent

associated with a weak mid-level perturbation over the Southeast

should aid this convective development, but multiple inversions

aloft noted in the 12Z observed MFL/TBW soundings should tend to

limit updraft intensities. Still, small hail and gusty winds could

occur with the stronger cores given the presence of moderate

instability and 30-35 kt of deep-layer shear.



..Gleason/Wendt.. 11/11/2026



$$