266
ACUS01 KWNS 241632
SWODY1
SPC AC 241631

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Mon Jun 24 2024

Valid 241630Z - 251200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
AND TONIGHT ACROSS SOUTHEAST MINNESOTA...CENTRAL AND SOUTHERN
WISCONSIN...NORTHEAST IOWA...AND NORTHERN ILLINOIS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
EASTERN NORTH CAROLINA...

...SUMMARY...
Scattered severe thunderstorms are expected over parts of the Upper
Midwest this afternoon into tonight. A corridor of potentially
widespread destructive wind gusts could develop over parts of
Minnesota into Wisconsin.

...Upper Midwest...
A weakening MCS continues to track eastward across central MN,
associated with a shortwave trough over southern Canada.  Extreme
instability will develop along the southern fringe of this MCS and
accompanying cloud shield, with hot/humid conditions leading to
MLCAPE values over 4500 J/kg by late afternoon across southwest MN.
Very warm temperatures aloft will likely suppress convective
development in this volatile air mass, but strengthening
southwesterly low-level winds by early evening will enhance warm
advection and likely lead to thunderstorms over central MN.  Initial
storms will be supercellular, with forecast soundings showing ample
low level and deep-layer shear to support a risk of very large hail,
damaging winds, and a few tornadoes.

As the evening progresses, most morning CAM solutions indicate that
the cluster of supercells will grow upscale into a fast moving
bowing MCS.  However, there is considerable diversity regarding the
track of the most intense storms.  Given the very warm temperatures
aloft, it seems likely the storms will track southeastward along the
thermal gradient - across central/southern WI and into northern IL.
The potential exists for a corridor of widespread and occasionally
significant (exceeding 65 kt) wind damage, so have upgraded to ENH.
The low-level air mass will become increasingly less unstable as the
storms move across Lake Michigan and into northern IN by early Tue
morning, suggesting a weakening trend.

...Central High Plains...
Scattered high-based showers and thunderstorms are expected to
develop over the central Rockies and Black Hills today and spread
eastward into parts of SD/NE/KS.  Hot surface temperatures and
inverted-v profiles will support a risk of gusty/damaging winds with
this activity for a few hours early this evening.

...Eastern NC/SC...
A surface front is sagging southeastward across NC today, with a
very moist and moderately unstable air mass in place ahead of the
front.  Thunderstorms are expected to form in this environment, with
sufficient westerly flow aloft to help organize the storms and
promote a risk of damaging wind gusts.  Given the amount of heating
that is occurring in eastern NC, and morning guidance showing
substantial coverage of storms, have added a SLGT risk for parts of
this area.

..Hart/Halbert/Weinman.. 06/24/2024

$$