URGENT - IMMEDIATE BROADCAST REQUESTED

Severe Thunderstorm Watch Number 577

NWS Storm Prediction Center Norman OK

320 PM EDT Wed Aug 12 2026

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of

Extreme southeast Illinois

Southern Indiana

North central and central Kentucky

* Effective this Wednesday afternoon and evening from 320 PM

until 900 PM EDT.

* Primary threats include...

Scattered damaging winds likely with isolated significant gusts

to 75 mph possible

Isolated large hail events to 1.5 inches in diameter possible

A tornado or two possible

SUMMARY...Thunderstorms are expected to evolve into a cluster and

spread southeastward from southern Indiana into Kentucky through

this evening. Wind damage and occasional severe gusts of 60-75 mph

will be the main threat, though isolated large hail of 1-1.5 inches

in diameter will be possible with the strongest storms. An isolated

tornado or two may also occur where storms interact with a residual

outflow boundary.

The severe thunderstorm watch area is approximately along and 80

statute miles east and west of a line from 55 miles northwest of

Louisville KY to 55 miles south of Louisville KY. For a complete

depiction of the watch see the associated watch outline update

(WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are

favorable for severe thunderstorms in and close to the watch area.

Persons in these areas should be on the lookout for threatening

weather conditions and listen for later statements and possible

warnings. Severe thunderstorms can and occasionally do produce

tornadoes.

Mesoscale Discussion 1958

NWS Storm Prediction Center Norman OK

0433 PM CDT Wed Aug 12 2026

Areas affected...Eastern Missouri into the lower Ohio River Valley

Concerning...Severe Thunderstorm Watch 577...

Valid 122133Z - 122330Z

The severe weather threat for Severe Thunderstorm Watch 577

continues.

SUMMARY...Severe thunderstorms will continue to pose a severe wind

and hail threat for the next hour or two, but should become

increasingly sporadic through the evening hours. Downstream watch

issuance will most likely not be required.

DISCUSSION...The remnants of an MCS continue to push southward

across the lower OH Valley, and although storm mode has become

increasingly disorganized and outflow-dominant (likely a consequence

of diminishing deep-layer wind shear with southward extent),

lightning counts have increased over the past 20 minutes within a

few cells from eastern MO into far southwest IN. This uptick in

intensity comes as convection begins to push into a regional

buoyancy maximum where MLCAPE was recently analyzed to be around

3500 J/kg. Consequently, the potential for large hail (most likely

around one inch) and strong/severe downburst winds should linger for

the next 1-2 hours as convection migrates through the best

thermodynamic environment.

However, regional reflectivity/velocity imagery shows that much of

this activity is quickly becoming displaced behind a coherent

convective outflow and/or has storm motions into the cold pool.

Weaker deep-layer wind shear with southward extent should maintain

the outflow-dominant nature of the convection and will eventually

promote storm weakening and an increasingly isolated severe threat

heading into the mid/late evening. Latest HRRR/RRFS time-lagged

guidance captures this trend well and suggests the severe threat may

not extend much beyond the southern bounds of WW 577. While

convective trends will continue to be monitored as storms push

through the buoyancy maximum, downstream watch issuance is currently

not anticipated.

This watch has expired.