Severe Thunderstorm Warning 340, NWS Des Moines, IA

903 
WWUS53 KDMX 150728
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
228 AM CDT Tue Sep 15 2026

IAC001-077-150738-
/O.EXP.KDMX.SV.W.0340.000000T0000Z-260915T0730Z/
Guthrie IA-Adair IA-
228 AM CDT Tue Sep 15 2026

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN GUTHRIE AND NORTHERN
ADAIR COUNTIES WILL EXPIRE AT 230 AM CDT...

The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.  However, gusty winds and heavy rain are still
possible with this thunderstorm.

LAT...LON 4172 9428 4160 9428 4160 9424 4143 9424
      4141 9462 4165 9464
TIME...MOT...LOC 0728Z 259DEG 44KT 4162 9423 

$$

Dodson

Area Forecast Discussion
National Weather Service Des Moines IA
1253 AM CDT Tue Sep 15 2026

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Severe thunderstorms late this afternoon into this evening
  with large hail, damaging wind gust, and a few tornadoes
  possible. Heavy rainfall with the potential for flash flooding
  becomes an increasing concern overnight, particularly in
  cities and towns.

- Heavy rain and storm chances continue through at least the
  middle of the week and possibly the end of the week, leading
  to both flash flooding and river flooding concerns.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 355 PM CDT Mon Sep 14 2026

The main weather theme over the period will be an active, wet
pattern into this next weekend. Of course, there will be intervals
of dry conditions, but rounds of rainfall will lead to increasing
threats of flash flooding over varying parts of the state. All of
the rainfall will also lead to rises on many if not most of our area
waterways. In some places, this may push the rivers above flood
stage. In addition, there is the risk of severe storms late this
afternoon into this evening before the event transitions to heavy
rainfall and flash flooding potential.

At present, the warm air advection wing of showers and thunderstorms
has lifted northeastward through much of central Iowa early this
afternoon. One of the forecast questions in previous days has been
the amount of clearing and potential destabilization. GOES-East
visible satellite imagery shows clearing in southwestern Iowa, which
should migrate into central Iowa. To the north over northern Iowa,
cloud cover may linger along with showers and this may create a
differential heating boundary in addition to the synoptic cold front
that will move in late today into tonight. Forecast soundings show
low level warm layer capping, which is expected to inhibit any
surface based storms. However, if storms are able to develop and
overcome this inhibition through daytime boundary layer mixing, a
few tornadoes would be possible given the strong kinematic
environment. If surface based storms do not form, elevated storms
are likely with strong MUCAPE values and mid-level lapse rates
around 6C/km. As alluded to, there is no lack of kinematic forcing
and shear with the right entrance region of a jet streak over the
region. The storms being elevated does take some edge off of the
impressive deep layer shear and storm relative helicity (SRH)
values; however, the bulk shear and SRH values are still very
favorable for severe storms, including elevated supercells, at least
initially, until they merge into a line of storms. These storms
would pose a risk of damaging wind gusts and hail with the hail risk
waning as the storms merge into a line. As this occurs, the 0-3km
shear values over 30 knots are in place to support a mesovortex
potential, especially if a line of storms can orient itself north to
south and thus more orthogonal to the shear vector. This remains to
be seen whether anything to the surface could materialize.

While the severe risk will wane by late evening, the heavy rainfall
and flash flooding potential will be going up through the evening.
There will be strong moisture transport into the region on the nose
of the low level jet upwards of 50 knots. This will bring
precipitable water values (PWATS) up to around 2 inches with warm
cloud depths topping 4000m - both unusually high for mid-September.
The 850-300mb around 40 knots, this is a bit fast, but it is
oriented fairly parallel to the boundary, which would result in
repeat rounds of rain (aka training storms). Deterministic has 2 to
4 inches with ensemble localized probability matched mean
(LPMM) from the HREF and REFS of 3 to 5 inches with localized
bullseye amounts of 7" in southwest to northeast oriented swaths
from somewhere in southwest Iowa into central Iowa. These are
areas that saw significant rainfall middle of last week with
additional rainfall across much of the area today. NASA SPoRT
soil moisture percentiles show reduced capacity in those areas
and a heightened risk of flash flood potential. Thus, the flash
flood watch continues to look well placed for tonight into
Tuesday morning with a slight expansion on the eastern side,
which will be discussed more below.

The surface boundary is forecast to slip south of the state by
midday Tuesday, but this does not mean the end of heavy rainfall,
just a change in location. The elevated 850mb boundary never leaves
the state and is forecast to lift back northward Tuesday night into
Wednesday. So, while the highest PWATs may be pushed to around the
Missouri border Tuesday night, they will move back northward,
especially into the day Wednesday. Thus, the risk of heavy rainfall
and flash flooding potential in play is highest from roughly I-80
southward through Tuesday night into Wednesday morning. With the
risk for another round of heavy rainfall, have extended the flash
flood watch through through midday Wednesday. There may be some
adjustment in area, but for now have kept the watch as simple as
possible. There does remain uncertainty in the amount of coverage of
rain and storms on Wednesday, but the environment that will be in
place will be favorable for heavy rainfall.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 209 PM CDT Mon Sep 14 2026

On a broad scale, Iowa will reside in generally fast flow around mid-
level high pressure over the Deep South/Southeastern US, which will
migrate slowly back to the west by week's end. In this fast flow,
there will be a few shortwave troughs that pass through along with
fragmented vorticity pieces, which will interface with a surface and
elevated boundary draped across the region if not the state at
times. The pattern is thus conducive to additional rounds of
rainfall on what will be increasingly saturated soil and thus
increased risk of flash flooding with each successive round of rain.
This rainfall will route into waterways and lead to increasing river
levels with additional details in the hydrology discussion
below.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1253 AM CDT Tue Sep 15 2026

Showers and thunderstorms continue along and southeast of a
line from DSM to ALO. Other scattered showers are developing
just west of FOD. This is expected to continue through the night
before activity settles across southern IA later this morning.
Generally VFR conditions can be expected, with MVFR or brief IFR
conditions in the heaviest showers and storms. The TS threat
should diminish area wide by 11Z. Light winds overnight will
shift north behind a cold front Tuesday morning.

&&

.HYDROLOGY...
Issued at 210 PM CDT Mon Sep 14 2026

Flash flood and river flood concerns continue this week due to
forecast multiple rounds of moderate to heavy rain. Flash flooding
is more of a concern in the short term (later today into Tue
morning). Short term National Water Model rapid onset flooding (ROF)
guidance continues suggesting the greatest risk of flash flooding
mainly between US Hwy 30 and the MO border, or roughly the same area
included in the current flood watch. Most likely scenario will be
ponding and low end flash flooding, however if QPF overachieves then
pockets of more significant flash flooding may occur especially over
urban areas. Since general storm motion is anticipated to be from W-
E or SW-NE, small stream basins oriented in those directions would
be most susceptible to flash flood impacts especially with training
thunderstorm activity. Additional heavy rain will prolong flash
flood concerns beyond Tue morning.

Longer term, river flood concerns exist too. The NBM-forced National
Water Model (NWM) with 10 days of QPF shows significant within-bank
rises on many streams across roughly the southeast half of the CWA,
with some minor flooding possible. The GEFS-driven Hydrologic
Ensemble Forecasting Service (HEFS) basically agrees, with 50%
exceedance probabilities showing several streams reaching action
stage or minor flood stage in central IA. The 30% exceedance
probabilities show more pervasive minor flooding with a few
locations at moderate flooding. The 10% level shows moderate to
major river flooding across much of the southeast half of the CWA.
Variations in QPF location and amounts as well as mesoscale features
after each successive round will greatly dictate what happens, but
the river flooding component is worth monitoring closely.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Wednesday afternoon for IAZ025>028-034>039-
045>050-057>062-070>074-081>084-092>095.

&&

SHORT TERM...Ansorge
LONG TERM...Ansorge
AVIATION...Borghoff
HYDROLOGY...Zogg

Hazardous Weather Outlook
National Weather Service Des Moines IA
411 PM CDT Mon Sep 14 2026

IAZ025>028-034>039-045>050-057>062-070>074-081>084-092>095-152115-
Wright-Franklin-Butler-Bremer-Calhoun-Webster-Hamilton-Hardin-
Grundy-Black Hawk-Carroll-Greene-Boone-Story-Marshall-Tama-
Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-Cass-Adair-Madison-
Warren-Marion-Adams-Union-Clarke-Lucas-Taylor-Ringgold-Decatur-
Wayne-
411 PM CDT Mon Sep 14 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

A Flash Flood Watch is in effect for the area. Please see our
website at weather.gov/dmx for additional details.

There is a Moderate Risk of excessive rainfall. Repeated rounds
of heavy rainfall will likely bring instances of flash flooding
overnight.

There is a Slight Risk of severe weather late this afternoon
through this evening, mainly across portions of west central into
central Iowa. All modes of severe weather may be possible
including large hail, damaging winds, and perhaps even a few
tornadoes.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

A Flash Flood Watch is in effect for the area through midday
Wednesday. Please see our website at weather.gov/dmx for
additional details.

Additional rounds of thunderstorms and heavy rainfall are expected
at times from Tuesday through much of this week. Flash flooding
and river flooding will become more of a threat with each round of
heavy rain.

.SPOTTER INFORMATION STATEMENT...

&&

NWS Des Moines will discontinue the Hazardous Weather Outlook
product (HWO) on September 30th, 2026. Weather hazards and
outlooks will continue to be provided through the standard
forecast channels, including weather briefing packets, forecast
discussions, weather story graphics, the experimental graphical
hazardous weather outlook, and updated hazard messaging. All
local products and visual tools are accessible directly at
weather.gov/desmoines.

IAZ004>007-015>017-023-024-033-044-075-085-086-096-097-152115-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Sac-Crawford-Mahaska-Monroe-Wapello-Appanoose-
Davis-
411 PM CDT Mon Sep 14 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

Thunderstorms with heavy rainfall are expected.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Additional rounds of thunderstorms and heavy rainfall are expected
at times from Tuesday through much of this week. Flash flooding
and river flooding will become more of a threat with each round of
heavy rain.

.SPOTTER INFORMATION STATEMENT...

&&

NWS Des Moines will discontinue the Hazardous Weather Outlook
product (HWO) on September 30th, 2026. Weather hazards and
outlooks will continue to be provided through the standard
forecast channels, including weather briefing packets, forecast
discussions, weather story graphics, the experimental graphical
hazardous weather outlook, and updated hazard messaging. All
local products and visual tools are accessible directly at
weather.gov/desmoines.

Preliminary Local Storm Report
National Weather Service Des Moines IA
1025 PM CDT Mon Sep 14 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1006 PM     Tstm Wnd Gst     3 S Creston             41.02N 94.36W
09/14/2026  M63 MPH          Union              IA   ASOS/AWOS

&&

Preliminary Local Storm Report
National Weather Service Des Moines IA
1042 PM CDT Mon Sep 14 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0925 PM     Tstm Wnd Dmg     1 SW Ames               42.02N 93.64W
09/14/2026                   Story              IA   Broadcast Media

            Received photos of downed trees and tree
            limbs around the Iowa State University
            campus. Time estimated from radar.

&&

67

Special Weather Statement
National Weather Service Des Moines IA
101 AM CDT Tue Sep 15 2026

IAZ057-058-070-071-150630-
Audubon IA-Guthrie IA-Adair IA-Cass IA-
101 AM CDT Tue Sep 15 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN CASS...GUTHRIE...
AUDUBON AND NORTHERN ADAIR COUNTIES THROUGH 130 AM CDT...

At 1259 AM CDT, trained weather spotters reported a strong
thunderstorm 13 miles southeast of Audubon, moving northeast at 45
mph.

HAZARD...Wind gusts of 50 to 55 mph and heavy rainfall of one to two
         inches.

SOURCE...Trained weather spotter reported a wind gust of 53 mph near
         Casey.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Ponding of water on roadways, low
         visibilities, and rises in small streams and creeks.

Locations impacted include...
Atlantic, Audubon, Guthrie Center, Stuart, Panora, Lake Panorama,
Anita, Exira, Adair, Elk Horn, Dexter, Casey, Diamondhead Lake,
Menlo, Kimballton, Brayton, Marne, Wiota, Lake Anita State Park, and
Audubon County Airport.

This includes Interstate 80 between mile markers 50 and 97.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4150 9515 4151 9504 4160 9504 4160 9509
      4172 9509 4173 9428 4160 9428 4160 9424
      4138 9424 4133 9515
TIME...MOT...LOC 0559Z 234DEG 38KT 4157 9476

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Dodson

Preliminary Local Storm Report
National Weather Service Des Moines IA
115 AM CDT Tue Sep 15 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1258 AM     Tstm Wnd Gst     1 SW Casey              41.50N 94.54W
09/15/2026  M53 MPH          Adair              IA   Trained Spotter

            A trained spotted measured a 53 mph gust on
            a hand-held anemometer at mile marker 82 on
            Interstate 80.

&&

AV

Special Weather Statement
National Weather Service Des Moines IA
128 AM CDT Tue Sep 15 2026

IAZ057>059-070>072-150700-
Audubon IA-Guthrie IA-Adair IA-Madison IA-Dallas IA-Cass IA-
128 AM CDT Tue Sep 15 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN MADISON...NORTHERN
CASS...GUTHRIE...AUDUBON...NORTHERN ADAIR AND SOUTHWESTERN DALLAS
COUNTIES THROUGH 200 AM CDT...

At 126 AM CDT, Doppler radar was tracking a strong thunderstorm 5
miles southwest of Guthrie Center, moving northeast at 45 mph.

HAZARD...Wind gusts of 50 to 55 mph and heavy rainfall of one to two
         inches.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Ponding of water on roadways, low
         visibilities, and rises in small streams and creeks.

Locations impacted include...
Atlantic, Audubon, Guthrie Center, Stuart, Earlham, Panora, Lake
Panorama, Anita, Exira, Redfield, Adair, Elk Horn, Dexter, Casey,
Diamondhead Lake, Menlo, Kimballton, Linden, Brayton, and Marne.

This includes Interstate 80 between mile markers 50 and 105.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4150 9515 4151 9504 4160 9504 4160 9509
      4172 9509 4175 9409 4136 9408 4131 9515
TIME...MOT...LOC 0626Z 245DEG 38KT 4161 9454

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Dodson