Severe Thunderstorm Warning 8, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
629 PM CDT Mon Mar 30 2026

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Warm, dry conditions with breezy winds today leading to
  elevated fire weather concerns through the afternoon.

- Severe thunderstorm potential over central Iowa, generally
  after 7 pm tonight. Hail and damaging winds are the primary
  concerns.

- Rain and thunderstorm chances develop again Tuesday afternoon
  into the evening, with a few strong storms possible in
  southeastern Iowa.

- Additional precipitation chances Wednesday through Friday,
  with rain and wintry precipitation Wednesday night into
  Thursday and more severe potential Friday.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 256 PM CDT Mon Mar 30 2026

Temperatures have warmed nicely this afternoon, with most of the
area in the upper 70s to low 80s as of 2 pm. With multiple hours of
sunlight left and efficient mixing taking place (as evidenced by the
breezy winds), record temperatures are still in reach. That said,
cloud cover has started to drift in from the west, filtering
sunshine. Should This continue, we could see clouds put an early
damper on temperatures. Regardless of whether we reach the record
highs, I'm sure nobody is complaining about temperatures in the
upper 70s and 80s in March.

With the warmer temperatures and efficient mixing, relative
humidities have fallen into the upper 20 to 30 percent range. Winds
have also been quite breezy, sustained around 15 to 20 mph with
gusts up to 30 mph in some locations. This has sites flirting with
red flag criteria, and while it's unlikely we reach the sustained 25
mph with < 25% humidity, elevated fire weather conditions are
ongoing across the area. Satellite has already detected numerous hot
spots through the day, signaling the dry conditions and increased
ignition potential in fuels. For these reasons, a special weather
statement for elevated fire weather conditions is out through 00z
(7pm CDT) this evening for all of central Iowa.

Moving forward through the day, we continue to watch the potential
for thunderstorms developing as warm, moist air streams
northward ahead of a weak surface low and kicks off storms
along a subtle convergence zone. Given the lack of any robust
features for guidance to latch onto, convective initiation has
been a bit inconsistent among the short range guidance, likely
due to the warm mid-level air. That said, if convective
initiation does occur, it seems the most likely time will be
right around to just after sunset (after 7pm), with the most
likely corridor being between US Highway 20 and Interstate 80
tracking east northeastward. These storms will be occurring in a
rather robust environment, with 1500 to 2000 J/kg of MLCAPE and
40 to 50 kts of deep layer shear, conducive for organized
convection and even a few supercells. That said, while the low
levels have plenty of rotation, hodographs farther aloft are
messy and lack the speed and directional changes one would
typically look for in a robust supercell environment. Likewise,
despite the 50+ dewpoints streaming into the area, model
soundings for central Iowa depict a deep "inverted-V" sounding,
characteristic of a well mixed and dry-sub cloud layer. All of
these features point toward a large hail and gusty wind threat,
with little threat for tornadoes given the high LCLs and
eventual elevated nature of storms occurring after sunset.
Strong downburst winds are certainly possible with any stronger
updrafts as heavy rain/hail falls into the dry layer, evaporates
and cools. Finally, given the CAPE and shear present, hail to
potentially large hail is possible, with larger hail (2"+) only
being a threat if any supercells develop. Severe storm chances
then diminish into the late evening hours, likely around
midnight. A low potential exists for elevated showers/storms to
persist through the overnight hours, mainly over southeastern
Iowa, given the stout low level jet nosed up into a weakly
unstable environment. However, this is a low confidence scenario
at this time.

A cold front will drop southward through the area overnight tonight
into Tuesday, shoving the low level moisture southeastward and
flipping our flow to southerly. Gusty winds will accompany the cold
air advection behind the front, but height rises and winds aloft
behind the front aren't overly strong, which should limit any
headline worthy winds on Tuesday. Much cooler temperatures will of
course also fill in behind the cold front, leading to a sharp
gradient in highs across the state tomorrow. The surface front makes
it's way completely through the area by late Tuesday afternoon, with
a few stronger storms possible along the boundary in the afternoon.
Wind and hail will again be the primary concerns with these storms
before the front pushes out of the area. Moisture advection and a
low level jet nosed into Iowa will keep scattered showers and
isolated storms percolating over the area through Tuesday night into
early Wednesday, albeit likely not severe.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 256 PM CDT Mon Mar 30 2026

The active forecast continues on Wednesday through the
end of the week. While a deepening trough develops over the western
U.S. Wednesday, a low ejecting out of the southwest will keep
showery precipitation continuing off and on through the day
Wednesday in the state before the upper level support arrives into
early Thursday. This precipitation will be mostly rain as warm air
advection begins to flow back into the southern half to two thirds
of the state as midlevel winds turn southwesterly and increase. In
saying this, we won't be looking at overly warm temperatures
Wednesday as highs only reach into the 40s to near 50 in the south
after falling into the 30s to low 40s to start the day behind the
cold front passage Tuesday. In northern Iowa, mid level winds will
keep the colder air reinforced, however, which may allow for a short
period of a wintry mix to start the day. The signal in forecast
soundings is not overly robust though with the easterly winds
reinforcing low to mid level dry air as well. Thus, northern Iowa is
more likely to stay dry early Wednesday. This unfortunately is not
the end of a discussion on winter weather as top down saturation
continues to occur through the day Wednesday with the wintry
precipitation reentering the conversation in northern Iowa on
Wednesday evening into early Thursday morning. There remains some
disagreement in forecast soundings in how the temperature profiles
play out which will have a big impact on precipitation type at the
surface. As noted in the previous discussion, afternoon cold rain
potentially changing to a wet snow or even staying as cold rain
remains the most plausible forecast at this point with deep
saturation through the DGZ, near isothermal temperatures to only
slightly warming above 0C at times and near freezing temperatures at
the surface. There are some soundings in northern Iowa, though
certainly closer to north central Iowa, with a warmer, nearing 2-3C
warm nose and then dropping below freezing at the surface. This is
showing up as a precipitation type of freezing rain in many cases,
but does not really scream freezing rain soundings. Won't completely
rule out some freezing rain or minimal icing on an elevated surface,
but not expecting much in the way of accumulating ice at this time
with rain to start, precipitation rate and the overall temperature
profiles near to only slightly below freezing limiting icing
efficiency. As such, have limited the overall icing amounts in the
forecast but kept with wintry mix wording with the cold rain/wet
snow the main forecast in northern Iowa.

After a short break later Thursday into early Friday, a stronger
system moves in by later Friday into Saturday. This will bring
another round of thunderstorms later Friday and a transition to
showery precipitation into Saturday with temperatures cooling once
again and potentially another round of cold rain mixed with wet snow
in northern Iowa. Will continue to monitor the details into later
this week, but some severe weather may be possible in the region as
well to end the week. Dry weather looks to return Sunday.
Temperatures will continue to fluctuate warming Thursday/Friday,
cooling Saturday and warming again Sunday with northern Iowa
remaining on the cold side and in the 30s-40s and southern Iowa in
the 60s-70s then 50s.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 629 PM CDT Mon Mar 30 2026

A lone storm is passing just north of DSM with additional
isolated storm activity possible this evening at DSM and OTM
with these chances being represented in PROB30 groups. While low
level winds will increase this evening, low level wind shear
(LLWS) may be rather sporadic and does look marginal. Focused
LLWS mentions at OTM and ALO where it looks to be the most
persistent. As a front pushes through the state after midnight
into Tuesday, will see gusty winds become from the northwest and
north. There continues to be a short period of MVFR ceilings
dropping over our northeastern terminals of MCW and ALO.
Additional storm chances are possible toward or after 18z at OTM
and have used SHRA vs TSRA in the PROB30 until timing can be
better refined.

&&

.CLIMATE...
Issued at 256 AM CDT Mon Mar 30 2026

     Forecast and Record High Temperatures for Select Central Iowa
Cities...

=============================================
            |        Monday        |  Period
            |  Forecast   Record/  |    of
City        |    High      Year    |  Record
=============================================
Des Moines        85      83/1968      1878-
Mason City        80      78/1967      1903-
Ottumwa           85      83/1967      1923-
Waterloo          81      84/1967      1895-
=============================================

&&

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

&&

SHORT TERM...Dodson
LONG TERM...05
AVIATION...Ansorge
CLIMATE...Hagenhoff

Hazardous Weather Outlook
National Weather Service Des Moines IA
408 PM CDT Mon Mar 30 2026

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-312115-
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-
408 PM CDT Mon Mar 30 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

Elevated fire weather conditions will diminish into this evening.

There is a Marginal (level 1 of 5) risk of severe storms tonight
in central to eastern Iowa. Large hail and damaging wind gusts
are the main hazards.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

There is a Marginal (level 1 of 5) risk of a few severe storms
over portions of southern and eastern Iowa Tuesday afternoon and
evening.

Additional precipitation chances exist through the remainder of
the week and into next weekend. While a wintry mix is possible
over northern Iowa Wednesday night into early Thursday, there will
also be additional severe weather potential in portions of the
state with these risks being better determined in the coming
days.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight and Tuesday.

Ansorge

Preliminary Local Storm Report
National Weather Service Des Moines IA
651 PM CDT Mon Mar 30 2026

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

0622 PM     Hail             Ankeny                  41.73N 93.60W
03/30/2026  E0.70 Inch       Polk               IA   Public

            Via KCCI viewer, time estimated from radar.

&&

De Bruin/Ansorge

Preliminary Local Storm Report
National Weather Service Des Moines IA
845 PM CDT Mon Mar 30 2026

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

0841 PM     Hail             6 ENE Marne             41.49N 95.01W
03/30/2026  E1.00 Inch       Cass               IA   Trained Spotter

&&

De Bruin/Ansorgee

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