Severe Thunderstorm Warning 262, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
403 AM CDT Fri Jul 3 2026

.KEY MESSAGES...

- Storms through today may lead to continued flooding or flash
  flooding concerns, especially in areas impacted by multiple
  rounds of heavy rainfall.

- Enhanced risk for severe weather in western Iowa, and Slight
  Risk for much of the state later this afternoon to evening.
  All hazards are possible with this activity.

- Uncertainty remains with the forecast into the holiday
  weekend, but hot and humid conditions persist with
  thunderstorm chances at times.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 401 AM CDT Fri Jul 3 2026

Very active weather conditions have become more common across much
of Iowa as of last night into early this morning, with radar
indicating scattered showers and thunderstorms over central into
northern Iowa. While the overall concern for severe weather lowered
over the last few hours or so, the main focus as of late shifted
significantly over to flooding, as storms have repeatedly developed
just south and near the I-80 corridor, before slowly lifting
north/northeast. Rainfall estimates over Polk to Black Hawk County
reached values generally around 2 inches, with localized amounts in
the 4-6 inch range. Hence the issuance of Flash Flood Warnings that
are in effect until 7am for Polk county and portions of Jasper
county. Despite the concern for the rain that has already fallen
over these areas, there remains the potential for additional heavy
rain as continued scattered showers and storms are showing
development over Madison and Warren counties that are expected to
lift into these already flooding areas, further enhancing the risk
for rather significant flooding risks over cities and towns, as well
as continued rises in rivers. We are also monitoring areas over
north-central Iowa for potential flooding, as rainfall amounts so
far are pushing over 2.5 to 3 inches over northern Webster and
Hamilton counties. Yet another area of concern is the line of
showers and thunderstorms in the form of an MCS that is moving over
western Iowa, which per radar trends and latest CAM runs have this
complex tracking southeast into the forecast area within the hour
and tracking across the state through the greater majority of the
morning. With this MCS will come returning chances for severe
weather, with the environment ahead of this feature characterized by
3000-4000 J/kg, while the effective shear of 30 knots in western
Iowa decreases with eastern extent. The main hazards of concern
would be damaging winds and small hail as it enters the western part
of the forecast area, transitioning to more of an additional hydro
threat given high PWATS and warm cloud depths that remain overhead.
By mid to late morning, this MCS should have weakened considerably,
with model guidance generally showing it exiting the area somewhere
after 10a-noon.

Temperatures given the presence of showers and storms through much
of the morning, as well as lingering clouds will likely lead to some
lowering of highs later on today, though in terms of heat headlines,
no changes were made over the far southern portion of the forecast
where the least of affects are anticipated by the activity through
the day, where heat indices near 100 degrees are most likely. While
dry conditions are expected over the afternoon across Central Iowa,
the boundary over north/north central Iowa is expected to see
development once again of showers and thunderstorms after roughly 4-
6 pm, and increasing in coverage through the evening. This activity
is anticipated to dive southeast with time, into an environment that
will have more than favorable instability overhead, while shear of
less 30 knots may lead to more of a messy storm environment. The
primary severe hazards again would be damaging winds and large hail,
given DCAPE values over 1000 J/kg and lapse rates around 7 C/km. An
Enhanced Risk per SPC remains over western Iowa, with a Slight Risk
across the greater majority of Iowa. Additional heavy rain will be
of high concern as well, especially in the areas mentioned above
that have already experienced flooding, with a Slight Risk for
excessive rainfall from the WPC.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 407 PM CDT Thu Jul 2 2026

The synoptic pattern begins to transition to a more zonal flow
pattern through the day Friday and into the weekend. This generally
keeps the warm and moist conditions going through the weekend,
although some reprieve may be on the horizon. Models are currently
depicting a shortwave passing through the state Friday night into
Saturday morning, bringing another MCS across Iowa. This system will
likely ride along the mesoscale boundary/instability gradient
(similar to tonight's), which will likely be farther south in the
state. As this occurs, damaging winds and heavy rainfall will
accompany it, again bringing severe weather and flash flood concerns
Friday night into the morning of Independence Day. However, with the
less persistent synoptic pattern, conditions seem to stabilize at
least through the day on Saturday. The boundary will be pushed
either into southern Iowa or northern Missouri, acting as the focal
point for redevelopment on the afternoon and evening of Independence
Day. Therefore, the southerly extent of the Friday night into
Saturday morning storms may be able to spare much of Iowa from storm
chances later in the day Saturday. This would also lead to slightly
cooler conditions, albeit still warm in the upper 80s. There is
still a lot to happen between now and then, so stay tuned to the
forecast for the latest on the Independence Day forecast! Warm and
humid conditions then persist into the end of the weekend and early
next week, although still not to the extremes of the beginning of
this week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1252 AM CDT Fri Jul 3 2026

Shower and thunderstorm coverage has increased through the
evening and will generally continue at or near much of the
terminals at least through much of Friday morning. While highest
confidence on this activity is over the KDSM, KFOD, and KALO
terminals given current radar trends, timing and intensity of
further activity later in the period, particularly late in the
morning through the latter portions of the current period will
need to be further assessed and refined at all TAF sites, with
amendments likely. Periods of low ceilings falling below 3kft
and lowered visibilities due to heavy rainfall are likely,
leading to periods of MVFR/IFR. Guidance suggested some spotty
LLWS as well this morning, but with this limited coverage have
left out of this forecast.

&&

.HYDROLOGY...
Issued at 407 PM CDT Thu Jul 2 2026

Flash flood and river flood concerns exist over at least the next
couple days due to heavy rainfall potential mentioned above.
Greatest concerns are across northern Iowa mainly coincident with
the flash flood watch. Main flash flood concerns would be in
cities and towns. Soil moisture in some areas has significantly
increased due to heavy rain over the past couple days. Additional
rainfall combined with relatively short soil recovery times may
lead to more runoff than we have recently seen, especially if it
falls in those areas, increasing the flash flood risk to within
flash flood watch criteria. Lower risk of flash flooding exists
farther south into central Iowa. Ponding looks to be the most
likely outcome at this time. If flash flooding occurred then it
would again be most likely in cities and towns.

Flash flood concerns continue into Friday with more heavy rain
possible. Confidence is relatively low in exact placements and
amounts. If the weather evolves tonight as expected then the
greatest risk on Friday would likely be along and north of the US
30 corridor, with lower risk farther south again.

River flooding would tend to be a longer term concern, depending on
heavy rain evolution over the next couple days. National Water
Model, HEFS and QPF ensemble hydrograph output suggest the most
likely scenario would be minor to significant within-bank rises on
many streams north of US 30, with a couple locations possibly
seeing minor flooding. If rainfall is higher than expected then
locally higher river levels would be possible.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 AM CDT this morning for IAZ004>007-
015>017-023>028-033>039-044>050-057>062.
Extreme Heat Warning until 10 PM CDT this evening for
IAZ084>086-092>097.

&&

SHORT TERM...Bury
LONG TERM...Dodson
AVIATION...Bury
HYDROLOGY...Zogg

Hazardous Weather Outlook
National Weather Service Des Moines IA
312 PM CDT Thu Jul 2 2026

IAZ044>050-057-058-070-071-081-032015-
Crawford-Carroll-Greene-Boone-Story-Marshall-Tama-Audubon-Guthrie-
Cass-Adair-Adams-
312 PM CDT Thu Jul 2 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Warm and humid conditions continue this afternoon. There is a
Slight (Level 2 of 5) Risk for severe storms from this afternoon
into evening, and again overnight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is an Enhanced (Level 3 of 5) to Slight (Level 2 of 5) Risk
for Severe Storms on Friday with multiple rounds of storms
possible from the morning through the evening.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed at times tonight into Friday.

IAZ004>007-015>017-023>028-033>039-032015-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-
312 PM CDT Thu Jul 2 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

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

There is a Slight (Level 2 of 5) Risk for severe storms from this
afternoon into evening, and again overnight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is an Enhanced (Level 3 of 5) to Slight (Level 2 of 5) Risk
for Severe Storms on Friday with multiple rounds of storms
possible from the morning through the evening.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed at times tonight into Friday.

IAZ084>086-092>097-032015-
Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-Appanoose-
Davis-
312 PM CDT Thu Jul 2 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

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

There is a Marginal (Level 1 of 5) Risk for severe storms from
this afternoon into evening, and again overnight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

An Extreme Heat Warning is in effect for the area through Friday
night. Please refer to the National Weather Service website at
weather.gov/desmoines for further details.

There is a Slight (Level 2 of 5) Risk for Severe Storms on Friday
with multiple rounds of storms possible from the morning through
the evening.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed at times tonight into Friday.

IAZ059>062-072>075-082-083-032015-
Dallas-Polk-Jasper-Poweshiek-Madison-Warren-Marion-Mahaska-Union-
Clarke-
312 PM CDT Thu Jul 2 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

An Extreme Heat Warning is in effect for the area into tonight.
Please refer to the National Weather Service website at
weather.gov/desmoines for further details.

There is a Slight (Level 2 of 5) to Marginal (Level 1 of 5) Risk
for Severe Storms this afternoon into evening, and again
overnight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is a Slight (Level 2 of 5) Risk for Severe Storms on Friday
with multiple rounds of storms possible from the morning through
the evening.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed at times tonight into Friday.

Preliminary Local Storm Report
National Weather Service Des Moines IA
126 AM CDT Fri Jul 3 2026

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

1145 PM     Rain             3 NNW Elkhart           41.83N 93.54W
07/02/2026  M7.61 Inch       Polk               IA   Public

            Personal weather station rainfall so far.

1256 AM     Rain             1 NW Ankeny             41.75N 93.62W
07/03/2026  M5.65 Inch       Polk               IA   Public

0102 AM     Rain             2 N Ankeny              41.77N 93.59W
07/03/2026  E5.50 Inch       Polk               IA   Public

            Via KCCI-TV.

1143 PM     Rain             Maxwell                 41.89N 93.40W
07/02/2026  M4.98 Inch       Story              IA   Public

            Personal weather station KIAMAXWE23 rainfall
            so far.

1143 PM     Rain             Cambridge               41.90N 93.53W
07/02/2026  M4.73 Inch       Story              IA   Public

            Personal weather station KIACAMBR11 rainfall
            so far.

&&

Preliminary Local Storm Report
National Weather Service Des Moines IA
132 AM CDT Fri Jul 3 2026

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

0132 AM     Rain             2 NNW Alleman           41.84N 93.62W
07/03/2026  M4.98 Inch       Polk               IA   Mesonet

            Iowa Flood Center gage near NW 2nd St at
            Alleman.

&&

Ansorge

Preliminary Local Storm Report
National Weather Service Des Moines IA
213 AM CDT Fri Jul 3 2026

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

0148 AM     Flash Flood      3 WSW Elkhart           41.78N 93.57W
07/03/2026                   Polk               IA   Dept of Highways

            Iowa DOT is closing I-35 northbound from
            mile marker 94 to 97. The water is 6-12
            inches deep with some reports as high as
            waist deep.

&&

Ansorge

Preliminary Local Storm Report
National Weather Service Des Moines IA
214 AM CDT Fri Jul 3 2026

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

0210 AM     Rain             Alleman                 41.82N 93.61W
07/03/2026  M8.60 Inch       Polk               IA   Broadcast Media

&&

Ansorge

Preliminary Local Storm Report
National Weather Service Des Moines IA
326 AM CDT Fri Jul 3 2026

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

0222 AM     Flood            3 SE Alleman            41.79N 93.57W
07/03/2026                   Polk               IA   Dept of Highways

            I-35 southbound exit ramp to NE 126th Avenue
            East is flooded.

&&

Ansorge