Severe Thunderstorm Warning 13, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
1259 PM CDT Thu Apr 2 2026

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Showers continue through this morning. Severe thunderstorms
  in central to eastern Iowa this afternoon. All severe hazards
  are possible.

- Severe storms Friday afternoon and evening in southern half
  of Iowa with a Enhanced Risk (level 3 of 5) for severe storms.
  All severe hazards are possible.

- Cooler and quite this weekend, could become active again later
  next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 309 AM CDT Thu Apr 2 2026

Surface low pressure sits across western Kansas early this morning
broad lift across Iowa and the 850 mb LLJ nosing up into southern
Iowa. This has allowed for widespread showers to persist through the
overnight along with a few embedded rumbles of thunder. That LLJ
will increase to 50-60+ kts and push into Iowa through this morning,
helping to maintain showers across the area, ending west to east
midday as the surface low lifts into Iowa. As the low tracks across
Iowa this afternoon a dry slot will develop, allowing for deeper
mixing and deep instability development where we get clearing.
Environmental winds increase in this slot with HREF mean gusts of 35-
40+ mph gusts in southeast Iowa. Soundings indicate periods of 40-
50+ kts at the top of the mixed layer in southeast Iowa, which may
allow for an occasional stronger gust this afternoon. Conditions are
better east of the area into the Quad Cities CWA where the wind
advisory has been issued.

The surface low reach south-central Iowa by around 18z and
pushes to eastern Iowa by around 23z which will define the
narrow window for severe storms here. Instability in that clear
slot is expected to increase to 1000-1500 J/kg of MLCAPE along
with ~40 kts of 0-6 km shear which is more than sufficient for
convective initiation. Mid level lapse rates are around 7 C/km
along with 150 m2/s2 0-1 km SRH. Expect that storms will
initialize in central Iowa early this afternoon and quickly
move east through the afternoon. Initial discrete to multicell
clusters in central Iowa growing upscale as they move into
eastern Iowa. All modes of severe weather are possible including
large hail, damaging wind gusts, and tornadoes. The tornado
threat should be maximized in the vicinity of the surface low
and with initial discrete storm mode.

Another upper level wave will amplify as it it move from the western
to central US on Friday. The low track remains fair consistent
across GFS and EC ensemble members, moving SW to NE across Iowa
through the afternoon, fed by a 50+ kt LLJ. Instability builds
through the afternoon with 2000+ J/kg MLCAPE and 40-50 kts of
0-6 km shear to organize storms. Again anticipate initial
discrete development, growing upscale as it moves into eastern
Iowa. These cells may remain discrete longer than the Thursday
storms, and CAMs indicate a line of supercells across central
Iowa before the line-out into eastern Iowa. This evolution is
supported by the expected mesoscale environment. Lapse rates
steepen to 8 C/km in the mid levels with 300+ m2/s2 of 0-1 km
SRH. As such, once again expect all modes of severe storms on
Friday including large hail, damaging wind gusts, and tornadoes.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 309 AM CDT Thu Apr 2 2026

Wrap around precipitation skims far northern Iowa on Saturday,
however will be of little impact with temperatures warm enough
for this to fall as light rain. Cooler behind the cold front
with highs on Saturday in the 40s. By Sunday temperatures warm
into the 50s with dry conditions. Cool and benign conditions
through the first part of next week, becoming more active later
in the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1236 PM CDT Thu Apr 2 2026

Stratiform rain continues over portions of northern to
northeastern Iowa early this afternoon with storm development
beginning to occur over southwest to south central Iowa.
Visibility reductions of MVFR to IFR continue to occur with this
rain, and localized lower visibilities may be realized during
some storms in mainly southern Iowa. Some of these storms may
also be severe with storm impacts most likely at KDSM and KOTM.
Winds will shift direction multiple times with winds out of the
south to southwest south of the warm front in southern Iowa and
out of the north to northwest or even out of the east to the
north of the warm front. Winds will become all out of the west
to northwest by 00Z with gusts of 20+ knots this afternoon at
all sites, and closer to 30-35+ knots in southeast Iowa near
KOTM. Some stronger gusts possible with storms. Ceilings remain
LIFR to IFR in much of northern Iowa with some clearing
occurring in southern Iowa. Ceilings remain degraded overall
until after 00Z when slow improvements may begin to occur west
to east in the south (to scattered MVFR), while IFR ceilings
remain across the north. Additional rain and storms are in the
forecast for Friday, but will be addressed in future issuances.

&&

.HYDROLOGY...
Issued at 130 PM CDT Wed Apr 1 2026

Continued short and long term flooding considerations exist due to
the imminent multi-day seasonally moderate to heavy rainfall event,
mainly across the southeast half of the CWA.

Short term considerations include potential ponding and low-end
flash flooding. Soil moisture values are generally running near to
below normal. That data combined with the QPF suggests any ponding
and flash flooding will be mainly rate vs. amount driven, with the
greatest risk in urban areas.

Longer term considerations include potential river flooding. GFS-
and NBM-forced National Water Model, HEFS and QPF ensemble
hydrographs indicate the most likely scenario will be moderate to
significant within-bank rises. A few locations may reach flood
stage, however minor flooding would be expected at most if it
occurs. The peaks on most rivers will occur this weekend into early
next week. Greater concern is the next few days of rainfall may set
the stage for more significant impacts going forward if the wet
pattern continues.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

SHORT TERM...Hagenhoff
LONG TERM...Hagenhoff
AVIATION...05
HYDROLOGY...Zogg

Hazardous Weather Outlook
National Weather Service Des Moines IA
447 AM CDT Thu Apr 2 2026

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-031000-
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-Audubon-Guthrie-Dallas-Polk-Jasper-
Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-
Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
447 AM CDT Thu Apr 2 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

There is a Slight (level 2 of 5) Risk of severe storms in central
Iowa this afternoon. Large hail, damaging wind gusts, and
tornadoes are all possible, especially towards eastern Iowa.
Pockets of heavy rain could also lead to ponding and flooding.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is an Enhanced (level 3 of 5) Risk of severe storms in
central and southern Iowa on Friday. Large hail, damaging wind
gusts, and tornadoes are all possible. Pockets of heavy rain
could also lead to ponding and flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today and Friday.

Hagenhoff