Areal Flood Warning 4, NWS Des Moines, IA

070 
WGUS83 KDMX 311631
FLSDMX

Flood Statement
National Weather Service Des Moines IA
1131 AM CDT Tue Aug 31 2021

IAC013-311641-
/O.CAN.KDMX.FA.W.0004.000000T0000Z-210831T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Black Hawk IA-
1131 AM CDT Tue Aug 31 2021

...FLOOD WARNING IS CANCELLED FOR NORTHEASTERN BLACK HAWK COUNTY...

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

LAT...LON 4264 9212 4264 9210 4261 9208 4257 9208
      4252 9208 4257 9214 4264 9218

$$

KCM

Area Forecast Discussion
National Weather Service Des Moines IA
628 AM CDT Tue Aug 31 2021

.DISCUSSION.../Today through Monday/
Issued at 251 AM CDT Tue Aug 31 2021

A generally warm and active weather pattern continues through this
week. Highlights:

- Thunderstorms today, especially southern half of Iowa this
  morning.
- Another round of storms likely late Thursday into Friday.
- Generally quieter weather for the weekend.

Several convective complexes developed across parts of South
Dakota, Nebraska, and Iowa overnight and produced spotty severe
weather reports from western into central Iowa, including around
the Des Moines metro. Those storms congealed into a line that has
surged south to the Iowa/Missouri border at this time, however,
additional storms from eastern Nebraska continue to push into
western Iowa and will pose a limited severe weather and flash
flooding threat through the morning hours, mainly in our
southwestern counties. High-resolution models have been having a
lot of trouble resolving the mesoscale features and details of
convective evolution all night, so POPs today are broad-brushed
and fairly expansive.

In wake of the storms this morning, a large high pressure ridge
extending from the Great Lakes southwestward toward Iowa will
dominate our weather for the next couple days. Although our
service area is on the southwestern fringes of its influence, this
high pressure area will provide us with a bit less hot/humid
conditions and generally dry weather through at least Wednesday
night. It is worth noting that the warm air advection zone over
the eastern High Plains, just southwest of the ridge, will likely
produce additional storms tonight as the nocturnal LLJ kicks in,
and these may be right on our doorstep to the west/southwest along
the Missouri River valley. However, severe weather would be
unlikely and the majority of forecast solutions do keep any such
activity just west/southwest of our area, so POPs are dry during
this time...for now.

By Wednesday night a large cyclone will be moving from western
into central Canada, trailing a 500 mb trough southwestward toward
the U.S. Pacific Northwest, and shunting the influence of the
large southern U.S. thermal ridge a bit further southward out of
Iowa. A leading shortwave impulse ahead of the main trough will
scoot by just to our northwest and north on Thursday/Thursday
night, then the primary trough will move through around early
Saturday or so. As the initial shortwave moves by, it will push a
weak surface trough across the region, and the broad lift
associated with the mid-level impulse, combined with strong low-
level warm air advection and resulting instability following the
retreating Great Lakes high pressure center, will promote the
development of a long swath of thunderstorms stretching down
Minnesota, across Iowa, and down into Kansas and Missouri sometime
around Thursday night. While more precise timing is uncertain,
POPs are likely during this time. Overall the severe weather
threat appears limited due to fairly low wind shear magnitude and
less than ideal diurnal timing, but there may be some potential,
and heavy rain will also be possible.

From Friday into early Saturday forecast confidence is a bit low
as much will depend on how far the Thursday night-ish trough makes
it through Iowa before it stalls out, but once the larger 500 mb
trough moves through the region around Saturday morning or so, it
should provide a respite of fairly quiet and comfortable weather
for the bulk of the weekend.

&&

.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 628 AM CDT Tue Aug 31 2021

SHRA/TSRA will affect DSM and OTM at times today, mainly within
the next few hours then perhaps again this afternoon, producing
brief intervals of MVFR visibility/ceilings and perhaps very
briefly IFR or lower. Outside of showers and storms, and further
north at FOD/MCW/ALO, VFR conditions will prevail through the
remainder of the TAF period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

DISCUSSION...Lee
AVIATION...Lee

Hazardous Weather Outlook
National Weather Service Des Moines IA
306 AM CDT Tue Aug 31 2021

IAZ004>007-015>017-023>026-033>038-044>050-057>062-070>075-
081>086-092>097-011100-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Sac-Calhoun-Webster-Hamilton-
Hardin-Grundy-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-
306 AM CDT Tue Aug 31 2021

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Thunderstorms will persist this morning, mainly across about the
southern half of Iowa, then clear out by this afternoon. There is
a low threat of severe weather and heavy rainfall, mainly in far
southwest Iowa this morning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Additional thunderstorms are expected at times from late Thursday
through Friday. The threat of severe weather is uncertain at this
time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

IAZ027-028-039-011100-
Butler-Bremer-Black Hawk-
306 AM CDT Tue Aug 31 2021

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

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

A few thunderstorms may be possible during the day today, but
severe weather is unlikely.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Additional thunderstorms are expected between Thursday night and
Friday night. The threat of severe weather is uncertain at this
time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Lee

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
723 AM CDT TUE AUG 31 2021

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

0649 AM     HEAVY RAIN       1 S ANITA               41.43N 94.77W
08/31/2021  M2.04 INCH       CASS               IA   COCORAHS

            24 HOUR TOTAL.

&&

ANSORGE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
725 AM CDT TUE AUG 31 2021

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

0700 AM     HEAVY RAIN       1 NW CENTERVILLE        40.74N 92.88W
08/31/2021  M3.05 INCH       APPANOOSE          IA   COCORAHS

            24 HOUR TOTAL.

&&

ANSORGE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
728 AM CDT TUE AUG 31 2021

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

0700 AM     HEAVY RAIN       2 WNW ATLANTIC          41.41N 95.05W
08/31/2021  M2.07 INCH       CASS               IA   AWOS

            24 HOUR TOTAL.

&&

ANSORGE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
746 AM CDT TUE AUG 31 2021

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

1156 PM     TSTM WND DMG     1 ENE DES MOINES        41.58N 93.60W
08/30/2021                   POLK               IA   FIRE DEPT/RESCUE

            12 INCH DIAMETER TREE LIMB FELL ON A POWER
            LINE, WHICH CAUSED A HOUSE FIRE. MULTIPLE 5
            TO 6 INCH DIAMETER BRANCHES DOWN IN THE AREA
            ALSO. TIME ESTIMATED.

&&

ANSORGE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
747 AM CDT TUE AUG 31 2021

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

0717 AM     HEAVY RAIN       1 WSW CORNING           40.99N 94.76W
08/31/2021  M2.22 INCH       ADAMS              IA   CO-OP OBSERVER

            24 HOUR RAIN TOTAL.

&&

ANSORGE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
802 AM CDT TUE AUG 31 2021

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

0800 AM     HEAVY RAIN       2 NNW CENTERVILLE       40.75N 92.89W
08/31/2021  M2.80 INCH       APPANOOSE          IA   TRAINED SPOTTER

&&

ANSORGE