Tornado Warning 52, NWS Des Moines, IA

003 
WWUS53 KDMX 190222
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
922 PM CDT Mon May 18 2026

IAC157-171-190231-
/O.CAN.KDMX.TO.W.0052.000000T0000Z-260519T0245Z/
Poweshiek IA-Tama IA-
922 PM CDT Mon May 18 2026

...THE TORNADO WARNING FOR NORTHERN POWESHIEK AND SOUTHERN TAMA
COUNTIES IS CANCELLED...

The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 1000 PM CDT for central Iowa.

LAT...LON 4176 9276 4193 9277 4211 9230 4182 9230
TIME...MOT...LOC 0220Z 244DEG 38KT 4192 9252 

$$

Donavon

Area Forecast Discussion
National Weather Service Des Moines IA
654 PM CDT Mon May 18 2026

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

.KEY MESSAGES...

- Enhanced Risk (level 3 of 5) of severe storms this evening
  into tonight. Tornadoes, damaging winds, and large hail are
  also possible as a line of storms moves west to east across
  the state. The highest probability of severe weather will be
  from southwestern into central and south central Iowa.

- Moderate Risk (level 3 of 4) of flash flooding in extreme
  southwest Iowa this evening into tonight, with a Slight Risk
  (level 2 of 4) across the remainder of our forecast area.
  Flood Watches are in effect from extreme southwest Iowa into
  adjacent parts of Nebraska and Missouri.

- Breezy late tonight into Tuesday, with cooler and drier
  weather through Wednesday. Lows in the 30s north and west
  Wednesday morning.

- Rain chances return in the latter part of the week,
  especially around Thursday night and Friday. Warmer weather
  forecast next week.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 122 PM CDT Mon May 18 2026

A deep 500 MB trough is digging across the Rockies and western
High Plains this afternoon, with a pronounced vorticity maximum
rounding the base and kicking out over eastern Colorado as a
negatively tilted shortwave that will move northeastward over
NE/IA/SD/MN this evening into early tonight. At the surface, an
elongated inverted trough stretches from an attendant surface
low developing near the TX panhandle northeastward over Kansas
and Iowa, roughly from around Red Oak to Cresco at this time.
West of the trough low stratus clouds have socked in the region
over northwestern Iowa and adjacent states, with limited
insolation reinforcing the developing baroclinic zone/effective
cold front, while east of the trough skies are partly cloudy
with cirrus also streaming overhead, resulting in limited
insolation but combined with south southwesterly flow to promote
modest diurnal warming.

As the 500 MB trough approaches the region this afternoon,
instability will increase to extreme levels over northeastern
Kansas where more clearing has occurred, and explosive
convection is anticipated in that area. The storms will then
propagate and expand northeastward ahead of the trough. Forecast
soundings in our area, especially central to southwestern areas,
depict very strong instability with CAPE values of 3000-4000
J/KG by late afternoon/early evening, along with strong shear as
even 0-500 meter SRH values exceed 200 m2/s2. This environment
will support supercells with all severe weather hazards possible
including large hail, damaging winds, and tornadoes. However,
satellite imagery indicates low-level cloud cover is steady to
increasing across much of our area and even into northwest
Missouri, and it remains to be seen how much clearing will
occur. Short-range mesoanalysis reflects this potential for
limited insolation with 0-3 KM CAPE values less than 50 J/KG
through the afternoon. This would limit near-surface stretching
and may somewhat mitigate tornado potential in much of our area.
That being said, if any clearing does reach our area then 0-3 KM
CAPE and surface stretching would increase rapidly, supporting a
heightened tornado threat. At this time it appears this
potential is highest in our southwestern counties and gradually
diminishing to the north and east, however, these trends will
be closely monitored as the day/evening progresses. Even if
tornadoes are limited in our area, elevated supercells
progressing into southern and central Iowa this evening would
still be capable of producing large hail and damaging wind
gusts, and the SPC has maintained an Enhanced severe weather
risk across much of our area accordingly. Once the initial round
of thunderstorms, forced by the 500 MB trough, exits our
eastern/southeastern counties around midnight or so, some
elevated showers/thunderstorms will linger overnight but be
weaker with more limited forcing and instability, and a rapidly
decreasing severe weather threat later tonight.

The aforementioned cold front will be exiting our southeastern
counties by early Tuesday morning, with any lingering elevated
showers or thunderstorms also moving off during the morning.
Behind the boundary, northwest winds will surge and bring
notably cooler weather across the area. Daytime highs Tuesday
will be about 15 degrees lower than today. Meanwhile, gusty
northwest winds spreading in behind the front late tonight will
continue through Tuesday morning as moderate cold air advection,
surface pressure rises, and a relatively tight pressure
gradient work through Iowa. Even then, wind potential is limited
by the shallow nature of the mixed layer, with forecast
soundings indicating top of the ML winds around 25-30 KT during
that time. Winds will then slowly diminish during the afternoon
as the tighter pressure gradient moves eastward and cold air
advection moderates.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 1250 PM CDT Mon May 18 2026

By Tuesday evening a large surface high pressure area will be
building down the northern High Plains and on Tuesday night will
settle across Iowa and Minnesota. This will lead to rapidly
diminishing winds around sunset Tuesday and much cooler
temperatures Tuesday night as winds go light or calm and skies
clear out, especially near the Minnesota border closer to the
center of the high and where chances for high cirrus clouds are
lowest. The result is forecast low temperatures early Wednesday
morning in the mid-to- upper 30s in our northern and western
counties, but any frost potential will be dependent on skies
remaining clear and winds becoming calm. This possibility will
be better assessed tonight and tomorrow.

From Wednesday through the end of this week a weak 500 MB low
will meander across southwestern Canada, with cyclonic flow
extending down across the U.S. Rockies and near Iowa. A series
of shortwave impulses moving through the flow will result in a
return of rain chances for our forecast area. Initially, on
Wednesday, the proximity of the slowly departing surface high
pressure area and associated dry air will inhibit any
precipitation chances. By Thursday atmospheric moisture and
instability will be gradually increasing however, and around
Thursday night and Friday the most pronounced 500 MB trough will
move overhead and bring higher rain chances (50-70%). In wake
of that trough, next weekend, weak subsidence may follow along
with weak surface riding, supporting mostly dry weather and much
lower rain chances (10-20%). Also of note is a consistent
signal for some degree of thermal ridging around Sunday into
early next week, especially from the EC and GEM, lending
confidence to warmer temperatures at the end of the current
7-day forecast. Climate Prediction Center outlooks also support
a likelihood of warmer than normal temperatures heading into
next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 629 PM CDT Mon May 18 2026

Mix of VFR to IFR conditions ongoing across the state early this
evening. Scattered showers and thunderstorms have begun moving
into portions of western Iowa with some severe storms possible,
especially in southern Iowa. Timing kept similar to previous
though extended the thunderstorm threat slightly, but still
expecting bulk of thunderstorm activity to be prior to 06Z with
showers lingering thereafter into early Tuesday morning. CIGs
drop to IFR behind the cold front late tonight into Tuesday
morning with increasing winds out of the northwest behind the
front as well. May see some visibility dips as showers/storms
move through, including into early Tuesday with the lingering
showers. Conditions turn back towards VFR by mid to late
afternoon but the gusty northwest winds will remain through much
of the daytime Tuesday.

&&

.HYDROLOGY...
Issued at 122 PM CDT Mon May 18 2026

Trends in flash flood tools suggest an increased risk of flash
flooding from activity this evening into tonight. NWM rapid
onset flooding (ROF) probabilities suggest the greatest risk
will be across our southwest CWA. Soil moisture in that area is
elevated due to heavy rainfall over the past few days. Heavy
rainfall tonight may lead to flash flooding due to decreased
soil capacity, or sheer rainfall intensity, or both. Main
concerns will be in towns, however lower areas including road
dips near creeks and small streams may see some issues as well.
In addition, any flooding will occur mainly during the nighttime
hours, which adds to its potential danger. For these reasons,
we issued a flood watch for some of our southern counties
through Tuesday morning.

Longer term, widespread river flooding is a minimal concern
this week. Some moderate to significant within-bank rises are
possible, however, especially in southern Iowa due to the
combination of recent and potential future heavy rainfall.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Tuesday morning for IAZ081>083-092>095.

&&

SHORT TERM...Lee
LONG TERM...Lee
AVIATION...05/MB
HYDROLOGY...Zogg

Hazardous Weather Outlook
National Weather Service Des Moines IA
418 PM CDT Mon May 18 2026

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
084>086-096-097-192130-
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-Lucas-Monroe-
Wapello-Appanoose-Davis-
418 PM CDT Mon May 18 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

Severe weather is forecast late this afternoon into this evening
with damaging wind gusts, large hail, and tornadoes all possible.
The highest risk is over southern Iowa. Non-severe thunderstorms
may linger after midnight.

Heavy rainfall is expected to occur at times with today's severe
storms. Flash flooding concerns are limited mainly to cities and
towns with the risk highest over far southern Iowa.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Thunderstorms return to the forecast at times later Thursday into
this weekend. Any chance of severe weather will be assessed in
the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed tonight. Rainfall reports are also
appreciated.

IAZ081>083-092>095-192130-
Adams-Union-Clarke-Taylor-Ringgold-Decatur-Wayne-
418 PM CDT Mon May 18 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

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

Severe weather is forecast late this afternoon into this evening
with damaging wind gusts, large hail, and tornadoes all possible.
The highest risk is over southern Iowa. Non-severe thunderstorms
may linger after midnight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Thunderstorms return to the forecast at times later Thursday into
this weekend. Any chance of severe weather will be assessed in
the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed tonight. Rainfall reports are also
appreciated.

Preliminary Local Storm Report
National Weather Service Des Moines IA
649 PM CDT Mon May 18 2026

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

0640 PM     Tornado          5 WNW Athelstan         40.60N 94.63W
05/18/2026                   Taylor             IA   Trained Spotter

            Trained spotter confirms tornado. Time
            estimated via radar.

&&

TR

Preliminary Local Storm Report...Corrected
National Weather Service Des Moines IA
653 PM CDT Mon May 18 2026

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

0630 PM     Tornado          5 WNW Athelstan         40.60N 94.63W
05/18/2026                   Taylor             IA   Trained Spotter

            Trained spotter confirms tornado. Time
            estimated via radar.

&&

TR

Preliminary Local Storm Report
National Weather Service Des Moines IA
703 PM CDT Mon May 18 2026

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

0656 PM     Tornado          Benton                  40.70N 94.36W
05/18/2026                   Ringgold           IA   Emergency Mngr

            Emergency manager confirms tornado on the
            ground. Time estimated via radar.

&&

TR

Preliminary Local Storm Report
National Weather Service Des Moines IA
712 PM CDT Mon May 18 2026

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

0709 PM     Tornado          5 N Mount Ayr           40.78N 94.22W
05/18/2026                   Ringgold           IA   Emergency Mngr

            Multiple reports from emergency management
            of confirmed tornado.

&&

TR