Severe Thunderstorm Warning 55, NWS Des Moines, IA

Area Forecast Discussion...UPDATED
National Weather Service Des Moines IA
Issued by National Weather Service Twin Cities/Chanhassen MN
653 PM CDT Tue Apr 22 2025

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

.KEY MESSAGES...

- Shower & storm chances continue through the evening hours,
  with a few stronger storms being capable of producing gusty
  winds and hail.

- Additional shower and thunderstorm chances persist through
  the remainder of the work week. Some strong storm chances
  exist, but the overall severe threat is low.

- A brief break from rain on Saturday, but shower and storm
  chances return Sunday into early next week.

&&

.DISCUSSION...
Issued at 257 PM CDT Tue Apr 22 2025

A boundary will act as a focus point for additional showers and
convection to develop this afternoon & evening across southern
Iowa. Moderate elevated instability will be present that will
support a few rumbles of thunder and a few stronger storms. The
window for a severe thunderstorm is small, but non- zero. The
area of best wind shear is across northern Iowa while the better
instability is across southern Iowa. The area in between will
support the chance of stronger storms, possibly severe, albeit
unlikely. Latest hi-res guidance does redevelop convection this
evening in that region. Forecast soundings highlight favorable
lapse rates but not much else given light low level flow. This
should nearly remove the potential tornado threat from the
equation. Tonight, our low level boundary will push north and
allow for WAA & moisture advection to increase across central
and northern Iowa. Models indicate additional shower & T-shower
chances follow the boundary's northward push and these will
remain sub-severe. Low temperatures bottom out in the upper 40s
north to lower 50s with showers continuing into Wednesday.

Spring showers will dominate the remainder of the forecast period as
the thermal gradient remains on top of the region. This will serve
as a track for several rounds of showers & storms through the
remainder of the work week. Wednesday's forecast will see rain
showers likely across much of Iowa. Forecast soundings are rather
unremarkable with weak low level wind shear and modest instability
values. One could argue that there is an inverted-V set up present
that could support an isolated gusty wind threat with any
thunderstorm Friday PM. Lapse rates will remain favorable 7.5+ C/km
that should provide enough forcing for another day with isolated
strong to severe storms. SPC's SWO day 2 keeps a Marginal risk (1
out of 5) over much of the state for that isolated hail & gusty wind
threat. High temperatures reach into the low to mid 70s Wednesday
afternoon and likely the warmest day until next Monday. Thursday &
Friday trend a few degrees cooler, in the 60s and low 70s for highs,
with continued rain chances. Thursday offers us the best chance with
60 to 80+ PoPs overhead as the trough ejects out of the central
Plains. QPF forecasts highlight a high probability for much of
southern and central Iowa to see at least a half inch of rain by
Friday afternoon. The sfc low will weaken as it tracks through Iowa
into the Great Lakes region on Friday. Friday night into Saturday
will be quiet as a high pressure moves overhead ushering in a dry
air mass behind the departing low pressure. Warm air & moisture
advection returns Saturday night with intermittent rain chances
forecast through Tuesday evening. Highs in the 80s are likely Monday
and upper 70s Tuesday. The warmer temperatures will bring an
increased chance for severe weather Monday into Monday evening.
SPC does highlight our entire CWA in their day 7 SWO with a 15%
chance for severe weather.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 653 PM CDT Tue Apr 22 2025

VFR conditions are likely to prevail throughout much of the
period, along with near continuous chances for showers. A few
light showers across southern IA should increase in coverage
overnight and lift north toward central IA. A few TS will become
more likely as the evening progresses. Generally, confidence
is low for any TAF location being impacted by TS, so left it
out for now. The exception is for DSM late Wednesday afternoon
when a PROB30 is mentioned when instability increases further.

&&

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

&&

DISCUSSION...BPH
AVIATION...Borghoff

Hazardous Weather Outlook
National Weather Service Des Moines IA
Issued by National Weather Service Twin Cities/Chanhassen MN
248 PM CDT Tue Apr 22 2025

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-232000-
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-
248 PM CDT Tue Apr 22 2025

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Scattered thunderstorms the rest of today and tonight. A few may
be strong with gusty winds, hail, and locally heavy rains.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Additional chances for thunderstorms through Thursday, and again
early next week. Some storms could produce heavy rain, along with
a chance for severe weather.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this evening, and then again later in the
work week.

jrb

Special Weather Statement
National Weather Service Des Moines IA
Issued by National Weather Service Twin Cities/Chanhassen MN
1004 PM CDT Tue Apr 22 2025

IAZ093-230345-
Ringgold IA-
1004 PM CDT Tue Apr 22 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN RINGGOLD COUNTY
UNTIL 1045 PM CDT...

At 1004 PM CDT, Doppler radar was tracking a strong thunderstorm
over Mount Ayr, moving east at 15 mph.

HAZARD...Half inch size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible.

Locations impacted include...
  Mount Ayr, Kellerton, Benton, Delphos, Beaconsfield and Mt Ayr
  Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 4081 9402 4062 9402 4064 9434 4075 9437
TIME...MOT...LOC 0303Z 259DEG 14KT 4070 9428

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...<30 MPH

Borghoff

Special Weather Statement
National Weather Service Des Moines IA
Issued by National Weather Service Twin Cities/Chanhassen MN
1014 PM CDT Tue Apr 22 2025

IAZ048-230400-
Story IA-
1014 PM CDT Tue Apr 22 2025

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL STORY COUNTY UNTIL 11
PM CDT...

At 1014 PM CDT, Doppler radar was tracking a strong thunderstorm
near Nevada, moving east at 20 mph.

HAZARD...Penny size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible.

Locations impacted include...
  Ames, Nevada, Iowa State Center, Colo, Collins and Ames Municipal
  Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 4211 9324 4194 9323 4190 9323 4192 9365
      4206 9365
TIME...MOT...LOC 0313Z 263DEG 19KT 4199 9353

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...<30 MPH

Borghoff

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