Flash Flood Warning 18, NWS Des Moines, IA

504 
WGUS73 KDMX 041411
FFSDMX

Flash Flood Statement
National Weather Service Des Moines IA
911 AM CDT Sat Jul 4 2026

IAC025-027-073-161-041421-
/O.EXP.KDMX.FF.W.0018.000000T0000Z-260704T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Calhoun IA-Carroll IA-Greene IA-Sac IA-
911 AM CDT Sat Jul 4 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 915 AM CDT THIS MORNING FOR 
SOUTHERN CALHOUN, NORTHERN CARROLL, NORTHWESTERN GREENE AND 
SOUTHEASTERN SAC COUNTIES...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

&&

LAT...LON 4231 9507 4231 9486 4230 9440 4228 9440
      4224 9440 4221 9440 4221 9438 4199 9442
      4200 9455 4202 9463 4216 9509

$$

Zogg

Area Forecast Discussion
National Weather Service Des Moines IA
1102 PM CDT Fri Jul 3 2026

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

.KEY MESSAGES...

- Thunderstorm chances continue at times through the overnight
  hours. Damaging winds and heavy rainfall are the main
  concerns, although hail will also be possible with stronger
  storms.

- Additional heavy rainfall tonight could lead to new or
  worsening flash flood conditions, especially in areas that
  received significant rainfall last night.

- Scattered showers and non-severe thunderstorms possible on
  Independence Day, mainly over northern Iowa.

&&

.UPDATE...
Issued at 849 PM CDT Fri Jul 3 2026

Forecast remains on track. Opted to end the Extreme Heat Warning
early as temperatures and heat indices have fallen below
criteria.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 233 PM CDT Fri Jul 3 2026

After what was a very wet night and morning for central Iowa, we are
seeing a bit of a break in the activity today before more storms
develop again overnight. The environment left over from this
morning's storms is quickly recovering thanks to mostly clear skies
and persistent warm, moist air advecting into the area. This will
lead to more destabilization, generally along a mesoscale boundary
with an instability gradient setting from west to east over central
Iowa. There isn't much for synoptic forcing over Iowa this
afternoon, but as we approach peak heating, convergence along the
boundary may be sufficient to develop storms. The general timing for
this initiation looks to be around 23z to 00z at the earliest,
although short range guidance is a bit uncertain on when these
diurnally driven storms will develop, if at all. Something to
watch that's developing as this is being written, is the MCS
currently over Missouri producing a cloud shield and likely
limiting heating in Iowa. This could limit initiation later
today. That said, this activity find enough lift to take off
late this afternoon and into the evening, it will have access to
3000 to 4000 J/kg of CAPE, although wind shear will be modest
around 30 kts. Therefore, severe weather is certainly possible
if any stronger storms develop an organized updraft. Damaging
winds and hail will be the main concerns, with a low risk for
tornadoes given poor low level flow. Of similar concern will be
the potential for heavy rainfall in a moisture rich environment
combined with training storms over areas that had already
received heavy rainfall last night. This could exacerbate
ongoing flood conditions, or lead to new flooding in areas where
soils are saturated from last night's rain (primarily over
central into northeastern Iowa).

As we get later into the evening, the 850 mb jet will begin to ramp
up, nosing into southeastern Nebraska and southwestern Iowa. This
will interact with the boundary draped across the region, developing
storms to our west which are progged to grow upscale into a
mesoscale convective complex. Expectation would be for this complex
to ride along the nose of the low level jet and with the instability
gradient, tracking eastward into Iowa. This system could bring some
damaging wind gusts through the state overnight into early Saturday
morning. Likewise, heavy rainfall would be likely with this system,
potentially adding to the rainfall amounts from any previous
convection. Like the earlier, diurnally driven storms, CAMs are
struggling to get a handle on this complex, but it has been
fairly persistent from run-to-run, just with differing paths and
intensity. If no storms occur earlier in the night, it stands
to reason there will be a pocket of untapped air over Iowa that
this MCS could take advantage of, leading to a more intense
system. Conversely, if convection is ongoing much of the
evening, the atmosphere may be more worked over in central Iowa,
pushing the system farther south. Therefore, like much of the
activity this week, how this second wave plays out will be
dependent on the first. Aside from the severe chances, this MCS
will bring another shot of heavier rainfall, albeit more
progressive than the earlier storms. This would be additive to
any rain that occurs this afternoon. Total rainfall expected
this evening may range quite a bit depending on if we get both
waves, or just one or the other. That said, expectation is for
at least an additional 1 to 2 inches of rain falling over most
areas tonight, with some localized amounts of over 3 inches
possible. A Flood Watch remains in effect through Saturday
morning, and a number of area rivers continue to see rises
today. For more information on the hydrological concerns, see
the hydro discussion below.

The overnight storms generally depart the area early Saturday
morning, pushing the boundary to the south of Iowa. The upper level
pattern will also be transitioning to more of a zonal flow, and
losing some of the persistent low to mid level moisture advection as
flow flips to more west and northwesterly through the day. That
said, a shortwave aloft dropping out of Minnesota may still interact
with the residual moist and unstable air mass in Iowa, producing
some showers and thunderstorms in northern Iowa on Saturday.
Fortunately, wind shear is negligible, meaning this activity would
likely be pulsey and less organized. Therefore, the severe risk
seems minimal on Saturday, again assuming the surface boundary
pushes out of the area Saturday morning. If it doesn't,
diurnally driven storms could once again develop over southern
Iowa Saturday afternoon, but this seems like an outlier
scenario. Long story short, while the picture is becoming
clearer for Independence Day, make sure to keep an eye on the
forecast and radar on Saturday, especially if you have any
outdoor plans!

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 233 PM CDT Fri Jul 3 2026

Aside from a few scattered showers at times, we generally get a
break from the persistent thunderstorm chances Sunday into Monday,
as northerly flow and increasing pressure at the surface fully takes
over influence of Iowa. Temperatures respond accordingly, with
relatively cooler highs in the mid 80s. Widespread precipitation
chances look to return through the middle of next week, but more on
that once we are through the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1059 PM CDT Fri Jul 3 2026

VFR TAFs are prevailing across all TAF sites with this issuance.
Showers and storms are expected to increase in coverage and
remain through much of the overnight. Showers and storms will
likely bring lowered CIGs, low-end VFR/upper-end MVFR; as well
as, gusty and erratic winds. Showers and storms will gradually
start to taper off from west to east through the morning before
exiting entirely by Saturday afternoon. Outside of convection,
winds will be generally light and variable.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 AM CDT Saturday for IAZ023>028-033>039-
044>050-057>062-070>075-081>086.

&&

UPDATE...Vorst
SHORT TERM...Dodson
LONG TERM...Dodson
AVIATION...Vorst

Hazardous Weather Outlook
National Weather Service Des Moines IA
406 PM CDT Fri Jul 3 2026

IAZ004>007-015>017-092>097-042115-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis-
406 PM CDT Fri Jul 3 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

There is a chance for showers and storms this evening into the
overnight hours. There is a Slight risk for severe weather for
most of the area for storms arriving tonight, and an Enhanced Risk
in the far west.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Additional storm chances return Saturday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight.

IAZ023>028-033>039-044>050-057>062-070>075-081>086-042115-
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-
406 PM CDT Fri Jul 3 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 tonight. Please refer to
the National Weather Service website at weather.gov/desmoines for
further details.

There is a chance for showers and storms this evening into the
overnight hours. There is a Slight risk for severe weather for
most of the area for storms arriving tonight, and an Enhanced Risk
in the far west.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Additional storm chances return Saturday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight.

Preliminary Local Storm Report
National Weather Service Des Moines IA
208 AM CDT Sat Jul 4 2026

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

0120 AM     Flash Flood      Nevada                  42.02N 93.45W
07/04/2026                   Story              IA   Law Enforcement

            Vehicle stranded in a couple feet of water.
            Flash flooding observed in spots that are
            not known to flood in the area.

&&

MD

Preliminary Local Storm Report
National Weather Service Des Moines IA
215 AM CDT Sat Jul 4 2026

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

0213 AM     Tstm Wnd Gst     Des Moines Int Airport  41.54N 93.66W
07/04/2026  M58 MPH          Polk               IA   ASOS

&&

MD

Preliminary Local Storm Report
National Weather Service Des Moines IA
219 AM CDT Sat Jul 4 2026

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

0210 AM     Tstm Wnd Gst     1 WNW Carlisle          41.51N 93.51W
07/04/2026  M58 MPH          Warren             IA   Mesonet

            PWS gust.

&&

MD

Preliminary Local Storm Report
National Weather Service Des Moines IA
230 AM CDT Sat Jul 4 2026

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

0219 AM     Tstm Wnd Gst     Des Moines Int Airport  41.54N 93.66W
07/04/2026  E58 MPH          Polk               IA   ASOS

&&

MD

Preliminary Local Storm Report
National Weather Service Des Moines IA
248 AM CDT Sat Jul 4 2026

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

0240 AM     Tstm Wnd Gst     2 SSW Knoxville         41.30N 93.11W
07/04/2026  M62 MPH          Marion             IA   AWOS

&&

MD

Preliminary Local Storm Report
National Weather Service Des Moines IA
306 AM CDT Sat Jul 4 2026

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

0258 AM     Tstm Wnd Gst     3 ENE Searsboro         41.60N 92.65W
07/04/2026  M59 MPH          Poweshiek          IA   Mesonet

            PWS gust.

&&

MD