Severe Thunderstorm Warning 319, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
1248 PM CDT Wed Oct 30 2024

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Showers and storms expected (80-100%) today, especially this
  afternoon into the evening.

- Severe threat mainly in southern Iowa this afternoon and
  evening with damaging winds and a few tornadoes possible.

- Much cooler on Thursday with brisk northwest winds. Rain
  chances ending north in the morning

- Chances for rain return later Saturday and persist into early
  next week.

&&

.DISCUSSION...
Issued at 418 AM CDT Wed Oct 30 2024

Focus is on the next 24-30 hours as upper low across the Rockies
ejects into the Midwest. Currently, much of Iowa is in the warm
sector overnight with gusty south winds supporting temperatures
which are well above normal, mainly in the low 70s.  The winds are
expected to persist through sunrise and thereafter, mainly across
the southeast where low level southerly flow remains strong.
Meanwhile, a cold front has been progressing across Nebraska
overnight with some scattered storms along the boundary where
convergence has been maximized. This front works into western
Iowa this morning as a surface low forms in western Oklahoma.
Isentropic lift strengthens into the morning along with
increasing mid level kinematic forcing ahead of the approaching
short wave. Showers and embedded storms are expected to increase
in coverage along and behind the boundary by later morning and
into the early afternoon as the forcing intensifies.

By this afternoon, a rather narrow ribbon of near surface based
instability develops along and ahead of the boundary.  As mentioned
in previous discussion, there is little doubt about the strength of
the shear within the wind fields as the robust flow produces
considerable bulk shear and low level SRH values of 200-400 m2/s2 by
the late afternoon into the evening ahead of the boundary. This may
be enhanced by the surface low which moves toward south central Iowa
by mid evening leading to local areas of winds being backed more
than forecast.  The near surface based instability of 500-1500 J/KG,
while not overly high, has historically been sufficient in these
cooler season cases of producing strong enough updrafts for tornado
development.  Most of the convection allowing models start with
individual cells which quickly merging into QLCS in central into
southwest Iowa and into eastern Kansas.  The main concern would be a
few tornadoes in the south where instability is most robust along
with a few stronger wind gusts. While there may be some
stronger storms earlier in the afternoon, it appears the best
time for severe weather occurs toward sunset and into the mid
evening as the QLCS evolves and passes east through central and
southern Iowa. In addition, the forward motion of the storms may
approach 45-50kts which may catch people off guard with fast
arrival times.

In addition to the severe threat, PWATs continue to increase today
and climb to around 1.5" by this afternoon into the evening. A few
different rounds of storms are expected in the vicinity of the
boundary from midday into the evening, particularly from southwest
through central into northeast Iowa.  Models continue to indicate
from 1.5 to nearly 3" in this band by late tonight.  Given the
recent dryness, the overall threat for flooding remains low,
however some urban flooding may be an issue late this afternoon
into the evening, particularly if leaves and other fall rubbish
begins to collect and block surface drainage. This may lead to
extensive ponding near these drains and force water into areas
not usually impacted by these events.

The surface low exits to the northeast tonight with additional
deformation precipitation forming across northwest to north central
Iowa late tonight and lingering into Thursday morning as mid level
forcing associated with the upper low crosses the state.  Otherwise,
temperatures will be much cooler with highs in the 40s and 50s with
a brisk northwest wind for much of the day.

There is a brief break on Friday into early Saturday however another
western trof develops by this weekend into early next week with
impact expected for the state.  These begin by later Saturday as
theta-e advection intensifies into the state with increasing chances
for showers and a few storms.  The threat for precipitation then
lingers on and off into Tuesday before an upper low ejects from the
Desert Southwest and heads into the region.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1247 PM CDT Wed Oct 30 2024

Showers and thunderstorms are expected to fill in across Iowa
through this afternoon to evening, which will come with lowered
ceilings and periods of visibility restrictions at times. Storms
are expected to gradually move east/northeast across the state,
with the highest severe weather potential over southern Iowa.
Ceilings are expected to drop into MVFR/IFR within the next few
hours generally from west to east as lower ceilings move across
the area, and are expected to remain throughout the majority, if
not the entire upcoming TAF period. Winds will continue to shift
northwesterly through the remainder of the state as the front
passes through, with winds decreasing briefly, before northwest
flow settling across the state into Thursday brings a return to
breezy conditions.

&&

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

&&

DISCUSSION...Cogil
AVIATION...Bury

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Special Weather Statement
National Weather Service Des Moines IA
1131 AM CDT Wed Oct 30 2024

IAZ044-301700-
Crawford IA-
1131 AM CDT Wed Oct 30 2024

...A STRONG THUNDERSTORM WILL IMPACT WESTERN CRAWFORD COUNTY THROUGH
NOON CDT...

At 1130 AM CDT, Doppler radar was tracking a strong thunderstorm 6
miles southeast of Moorhead, or 23 miles southwest of Denison, moving
northeast at 45 mph.

HAZARD...Nickel size hail.

SOURCE...Radar indicated.

IMPACT...Minor hail damage to vegetation is possible.

Locations impacted include...
Dunlap, Schleswig, Charter Oak, Kiron, and Ricketts.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4218 9567 4221 9565 4221 9524 4186 9559
      4186 9567
TIME...MOT...LOC 1630Z 212DEG 39KT 4186 9576

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...<30 MPH

Jimenez

Special Weather Statement
National Weather Service Des Moines IA
1250 PM CDT Wed Oct 30 2024

IAZ045-046-057-058-070-071-301815-
Guthrie IA-Audubon IA-Greene IA-Adair IA-Carroll IA-Cass IA-
1250 PM CDT Wed Oct 30 2024

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN GREENE...EASTERN
CASS...GUTHRIE...AUDUBON...SOUTHERN CARROLL AND ADAIR COUNTIES
THROUGH 115 PM CDT...

At 1249 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 4 miles north of Audubon to 13 miles northeast
of Atlantic to 6 miles west of Lake Icaria. Movement was northeast at
50 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Audubon, Greenfield, Guthrie Center, Stuart, Manning, Coon Rapids,
Panora, Lake Panorama, Anita, Exira, Adair, Fontanelle, Scranton,
Bayard, Casey, Orient, Templeton, Massena, Menlo, and Bagley.

This includes Interstate 80 between mile markers 60 and 92.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4190 9509 4208 9452 4166 9432 4120 9434
      4116 9451 4116 9494 4142 9493 4172 9510
TIME...MOT...LOC 1749Z 237DEG 43KT 4178 9490 4148 9477 4107 9486

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Jimenez

Special Weather Statement
National Weather Service Des Moines IA
117 PM CDT Wed Oct 30 2024

IAZ034-035-045>047-058-059-301845-
Guthrie IA-Boone IA-Calhoun IA-Webster IA-Greene IA-Carroll IA-
Dallas IA-
117 PM CDT Wed Oct 30 2024

...STRONG THUNDERSTORMS WILL IMPACT GREENE...SOUTHWESTERN WEBSTER...
CENTRAL GUTHRIE...SOUTHEASTERN CALHOUN...SOUTHEASTERN CARROLL...BOONE
AND NORTHERN DALLAS COUNTIES THROUGH 145 PM CDT...

At 116 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles southeast of Glidden to 9 miles east of
Coon Rapids to 5 miles southeast of Guthrie Center. Movement was
northeast at 55 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Boone, Perry, Jefferson, Guthrie Center, Madrid, Ogden, Coon Rapids,
Glidden, Panora, Gowrie, Woodward, Lake Panorama, Boone Speedway,
Dayton, Grand Junction, Scranton, Bayard, Churdan, Farnhamville, and
Minburn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4241 9419 4218 9391 4185 9382 4180 9381
      4150 9450 4179 9459 4199 9484
TIME...MOT...LOC 1816Z 233DEG 48KT 4198 9465 4185 9450 4162 9443

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

Jimenez

Preliminary Local Storm Report
National Weather Service Des Moines IA
145 PM CDT Wed Oct 30 2024

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

0130 PM     Tstm Wnd Gst     6 ESE Greenfield        41.28N 94.34W
10/30/2024  M60 MPH          Adair              IA   Public

            Personal weather station.

&&