Severe Thunderstorm Warning 232, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
221 PM CDT Mon Jul 15 2024

.KEY MESSAGES...

- Enhanced Severe Storm Risk Through Evening with Risk of Higher
  End Damaging Winds, Some Hail and Possible Tornado
- Heat Advisory in place to this evening South
- Cooler and Mainly Dry Tuesday through Sunday

&&

.DISCUSSION...
Issued at 221 PM CDT Mon Jul 15 2024

Confidence Short Term: Medium

Warm layer aloft still holding down convection at 1815z with cu
field showing up along one of the many weak boundaries over the
region. The overall synoptic set up is the same with a trough of low
pressure from northern Wisconsin back to western MN, then south to
western Iowa. Weak lows are present in western MN and near Omaha.
VISSAT shows the area of cu and also the same location of the
highest SBCAPE of 6000 to 7000 J/kg and surface moisture
convergence. Currently there remains some weak MLCIN over
western Iowa where some convection is trying to fire. However,
just to the east of where some storms are beginning, the area is
totally uncapped with 4000 to 4500 J/kg MLCAPE. The more
widespread initiation is still expected between 21 to 22z.
Though the earlier HRRR runs today have been backing off on our
area to some degree, the latest 17z HRRR is now initiating
convection around 20 to 21z and quickly filling in an area of
discrete storms around US20 US30 corridor. This then grows
upscale into northern and west central Illinois. Trailing severe
convection begins to fill in between US20 and I80 between 22z
and 01z. So, holding on to similar thinking with the potential
still there. While the potential for widespread high end wind
event may be reduced slightly in this scenario, we should still
see some pockets of significant damaging winds within the
clusters of storms. The good news is that most of the storms
should exit the region around 02 to 03z and the remainder of the
night relatively quiet. Tomorrow was originally expected to be
dry, but there is another weak wave over Montana tracking
southeast. This may bring a few showers/isolated storms to the
region by Tuesday afternoon. The main theme for tomorrow and
moving forward is cooler temperatures. Highs tomorrow will range
from the upper 70s north to the lower to mid 80s south.
Tomorrow night as high pressure settles into the region, any
lingering showers should come to an end with cooler overnight
mins in the upper 50s to mid 60s.

.Long Term /Wednesday through Monday/...

Confidence: Medium

Most of the week will remain dry with cooler temperatures in the 70s
to lower 80s. Toward the weekend, we return to southerly flow with
chances once again for some convection by late Friday night west.
This trend will extend into the weekend, but with lower confidence
on coverage and timing. Temperatures should remain pleasant and in
the 70s to lower 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1230 PM CDT Mon Jul 15 2024

Highly uncertain forecast regarding convection to 00z.
Approaching H500 wave expected to break strong H700 cap between
20 and 22z. Weak wind shift continues from NW Iowa to about the
Quad Cities now, but should lift slightly north by 00z. CAMS
suggest the higher storm chance area between US20 and I80,
focusing mainly on FOD/ALO/DSM and perhaps later OTM. For now
have not hit conditions too hard, but will update for lower
cigs/vsbys and stronger convective wind gusts once storms form.
/rev

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for IAZ057>062-
070>075-081>086-092>097.

&&

DISCUSSION...REV
AVIATION...REV

Hazardous Weather Outlook
National Weather Service Des Moines IA
148 PM CDT Mon Jul 15 2024

IAZ057>062-070>075-081>086-092>097-161900-
Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-Cass-Adair-Madison-
Warren-Marion-Mahaska-Adams-Union-Clarke-Lucas-Monroe-Wapello-
Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis-
148 PM CDT Mon Jul 15 2024

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

A Heat Advisory is in effect for the area. Please refer to the
National Weather Service website at weather.gov/desmoines for
further details.

Strong to severe storms are expected this afternoon to evening
with the primary hazard being damaging wind gusts with a few
intense gusts over 75 mph possible, especially east of I-35 and
south of Highway 20. Hail and a few tornadoes are also possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed today.

IAZ004>007-015>017-023>028-033>039-044>050-161900-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene-
Boone-Story-Marshall-Tama-
148 PM CDT Mon Jul 15 2024

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

The heat wave will continue for the rest of the afternoon to
evening, with maximum heat index values up to 100 degrees over
northern Iowa.

Strong to severe storms are expected this afternoon to evening
with the primary hazard being damaging wind gusts with a few
intense gusts over 75 mph possible, especially east of I-35 and
south of Highway 20. Hail and a few tornadoes are also possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed today.