River Flood Warning 21, NWS Des Moines, IA

582 
WGUS83 KDMX 152322
FLSDMX

Flood Statement
National Weather Service Des Moines IA
622 PM CDT Tue Sep 15 2026

...The Flood Warning is cancelled for the following rivers in Iowa...

  Walnut Creek at Clive I-80/35 affecting Dallas and Polk Counties.

IAC049-153-160030-
/O.CAN.KDMX.FL.W.0021.000000T0000Z-260915T2322Z/
/CLVI4.1.ER.000000T0000Z.000000T0000Z.000000T0000Z.NO/
622 PM CDT Tue Sep 15 2026

...FLOOD WARNING IS CANCELLED...

The Flood Warning is cancelled for
  the Walnut Creek at Clive I-80/35, or from Little Walnut Creek to
  the North Walnut Creek.

* ADDITIONAL DETAILS...
  - At 6:13 PM CDT Tuesday the stage was 8.8 feet, and falling.
  - Forecast...The river is expected to fall to 8.0 feet this
    evening.
  - Flood stage is 9.0 feet.


&&

LAT...LON 4161 9383 4165 9382 4161 9370 4158 9373
      4160 9379


$$

Hagenhoff

Area Forecast Discussion
National Weather Service Des Moines IA
1212 PM CDT Tue Sep 15 2026

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

.KEY MESSAGES...

- Heavy rainfall with the potential for flash flooding will
  persist through cold frontal passage this afternoon.

- 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 314 AM CDT Tue Sep 15 2026

The early overnight surface analysis reveals an active synoptic
pattern across much of the central CONUS. An occluding 993 mb
surface low is centered over south-central Canada with a trailing
cold front oriented south-southwestward through the Central Plains
to the Four Corners. A secondary surface low is riding along the
front, while a stationary boundary extends southeastward across much
of the southern US. Meanwhile, yesterdays surface high has shifted
eastward and is centered over the northern Mid-Atlantic. Locally, a
combination of the approaching cold front and the secondary surface
low continues to drive showers and thunderstorms eastward across the
region, producing showers and thunderstorms with heavy rainfall
rates.

Through the remainder of the overnight period and into the day, the
cold front will slowly track through the DMX CWA, gradually pushing
the precipitation out of the area. Recent model runs show slight
variability regarding exact timing, but the consensus brings FROPA
through the region by early afternoon. Prior to FROPA, showers and
thunderstorms will persist across the southern half of the forecast
area. High precipitation efficiency is evident, with rain gauges
reporting rates of 1.5 to 2.5 inches per hour as the core of the
activity moves through the Des Moines metropolitan area and points
along the I-80 corridor. While widespread flash flooding is not
currently observed, a strong LLJ continues to transport rich
moisture into the region. With low-level flow aligned parallel to
the front, training convective cells remain likely until frontal
passage, elevating the threat for flash flooding.

Behind the front, a very brief lull in activity is expected as weak
surface high pressure builds in from the north today. However, upper-
level dynamics associated with the right entrance region of a
departing jet streak will lift the precipitation shield back
northward, bringing rain chances back to the area late Tuesday night
into Wednesday. Abundant moisture and strong synoptic lift will keep
heavy rainfall ingredients in place over already saturated soils,
maintaining a heightened flood risk. Consequently, a Flash Flood
Watch remains in effect through Wednesday afternoon, and the WPC
maintains a Slight Risk for Excessive Rainfall across much of the
forecast period.

An active frontal system and surface low will bring heavy rainfall
and potential flash flooding to the area through early afternoon
before a brief break in precipitation occurs behind the front.
However, upper-level jet dynamics will quickly push moisture back
northward late Tuesday night into Wednesday, prolonging heavy rain
risks over saturated ground and keeping the Flash Flood Watch
active.

&&

.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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1213 PM CDT Tue Sep 15 2026

Showers continue to sputter over central Iowa, but should see
these continue to sink slowly southward through the afternoon
into this evening. For FOD, MCW, and ALO, VFR conditions will
prevail with the rain to the south of these terminals through
the period. For DSM and OTM, showers will be off and on through
the rest of the day, but will focus over far southern Iowa/OTM
tonight into Wednesday morning. There is a short window of
thunder potential there, but confidence is sufficient only for
PROB30 at this time. Ceilings will also lower over far southern
Iowa toward sunrise Wednesday and lift northward through the end
of the period.

&&

.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 IAZ045>050-057>062-
070>074-081>084-092>095.

&&

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

Hazardous Weather Outlook
National Weather Service Des Moines IA
1012 AM CDT Tue Sep 15 2026

IAZ045>050-057>062-070>074-081>084-092>095-161515-
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-
1012 AM CDT Tue Sep 15 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

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

There's a Slight Risk for excessive rainfall today as a cold front
crosses through the area. Flash flooding remains possible
especially for locations that receive multiple rounds of rain.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

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 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...

Spotters are encouraged to safely report instances of flash
flooding.

&&

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>028-033>039-044-075-085-086-096-097-161515-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Mahaska-Monroe-
Wapello-Appanoose-Davis-
1012 AM CDT Tue Sep 15 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

A few thunderstorms possible in the early afternoon.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Additional rounds of thunderstorms and heavy rainfall are expected
at times 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
955 AM CDT Tue Sep 15 2026

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

0730 AM     Rain             Urbandale               41.64N 93.74W
09/15/2026  M4.30 Inch       Polk               IA   Broadcast Media

            Report relayed by broadcast media.

&&

AJJ

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

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

0623 AM     Rain             Casey                   41.51N 94.52W
09/15/2026  M3.10 Inch       Guthrie            IA   Trained Spotter

            Rain fell after this report.

&&

AJJ

Preliminary Local Storm Report
National Weather Service Des Moines IA
1000 AM CDT Tue Sep 15 2026

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

0800 AM     Rain             West Des Moines         41.57N 93.75W
09/15/2026  M3.50 Inch       Polk               IA   Public

            Rain fell after this report.

&&

AJJ

Preliminary Local Storm Report
National Weather Service Des Moines IA
1010 AM CDT Tue Sep 15 2026

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

0700 AM     Rain             3 NE Paton              42.19N 94.21W
09/15/2026  M2.25 Inch       Greene             IA   Public

            Measured from 7am Sept 14 to 7am Sept 15,
            rain ongoing, relayed via social media.

&&

AJJ

Preliminary Local Storm Report
National Weather Service Des Moines IA
1249 PM CDT Tue Sep 15 2026

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

0922 PM     Tstm Wnd Dmg     1 W Ames                42.02N 93.64W
09/14/2026                   Story              IA   Public

            Picture of tree damage near Welch Hall on
            ISU campus. Branches are between 6 and 8
            inches in diameter. Time estimated by radar.
            Relayed via social media.

&&

AJJ

Preliminary Local Storm Report
National Weather Service Des Moines IA
1252 PM CDT Tue Sep 15 2026

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

1100 AM     Rain             2 W Ankeny              41.73N 93.63W
09/15/2026  M3.30 Inch       Polk               IA   Trained Spotter

            24 hour total rain as of 11 AM. Rain
            ongoing, so not storm total.

&&

AJJ