Alert archive / Iowa / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 12, NWS Des Moines, IA

May 14, 2020Clarke County, Warren County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 14, 2020, 5:01 PM CDT for Clarke County, Warren County, Iowa. It was in force for 29 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 14, 2020, 5:01 PM CDT (22:01 UTC)
Expired: May 14, 2020, 5:30 PM CDT
In force: 29 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Clarke County, IA, Warren County, IA

The radar

The Des Moines radar (KDMX), 62 km from the middle of the area, began a volume at 22:02 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
May 14, 5:13 PM CDT	HAIL 1	8 E New Virginia, IA	REPORT FROM MPING: QUARTER (1.00 IN.).
May 14, 5:22 PM CDT	HAIL 0.88	7 E New Virginia, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 12 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 14, 4:24 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.0 hours before the alert went out and 232 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 519 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 70 m²/s²
0-3 km storm-relative helicity: 59 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

571 
WUUS53 KDMX 142201
SVRDMX
IAC039-181-142230-
/O.NEW.KDMX.SV.W.0012.200514T2201Z-200514T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
501 PM CDT Thu May 14 2020

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northeastern Clarke County in south central Iowa...
  Southern Warren County in south central Iowa...

* Until 530 PM CDT.

* At 501 PM CDT, a severe thunderstorm was located 10 miles southeast
  of Avenue Of The Saints Event Center, or 10 miles northeast of
  Osceola, moving east at 35 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Trained weather spotters.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  New Virginia, Otter Creek County Park and Lake Ahquabi State Park. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in Des Moines .

&&

LAT...LON 4114 9376 4124 9371 4134 9349 4119 9340
      4116 9351 4116 9356 4114 9356 4111 9367
TIME...MOT...LOC 2201Z 247DEG 31KT 4117 9370 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

Kotenberg

3 follow-up statements

444 
WWUS53 KDMX 142221
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
521 PM CDT Thu May 14 2020

IAC039-181-142230-
/O.CON.KDMX.SV.W.0012.000000T0000Z-200514T2230Z/
Clarke IA-Warren IA-
521 PM CDT Thu May 14 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM CDT
FOR NORTHEASTERN CLARKE AND SOUTHEASTERN WARREN COUNTIES...

At 521 PM CDT, a severe thunderstorm was located 11 miles south of
Indianola, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
New Virginia and Otter Creek County Park. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Des Moines .

&&

LAT...LON 4121 9372 4130 9346 4119 9340 4116 9351
      4116 9356 4114 9356 4111 9367 4114 9376
TIME...MOT...LOC 2221Z 249DEG 34KT 4119 9360 

HAIL...1.00IN
WIND...60MPH
 
$$

Kotenberg

507 
WWUS53 KDMX 142224
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
524 PM CDT Thu May 14 2020

IAC039-181-142230-
/O.CON.KDMX.SV.W.0012.000000T0000Z-200514T2230Z/
Clarke IA-Warren IA-
524 PM CDT Thu May 14 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM CDT
FOR NORTHEASTERN CLARKE AND SOUTHEASTERN WARREN COUNTIES...

At 524 PM CDT, a severe thunderstorm was located 11 miles south of
Indianola, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
New Virginia and Otter Creek County Park. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Des Moines .

&&

LAT...LON 4121 9372 4130 9346 4119 9340 4116 9351
      4116 9356 4114 9356 4111 9367 4114 9376
TIME...MOT...LOC 2224Z 249DEG 34KT 4120 9357 

HAIL...1.00IN
WIND...60MPH
 
$$

Kotenberg

140 
WWUS53 KDMX 142230
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
530 PM CDT Thu May 14 2020

IAC039-181-142240-
/O.EXP.KDMX.SV.W.0012.000000T0000Z-200514T2230Z/
Clarke IA-Warren IA-
530 PM CDT Thu May 14 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CLARKE AND
SOUTHEASTERN WARREN COUNTIES HAS EXPIRED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been allowed to expire.

A Severe Thunderstorm Watch remains in effect until midnight CDT for
south central Iowa.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Des Moines .


LAT...LON 4121 9372 4130 9346 4119 9340 4116 9351
      4116 9356 4114 9356 4111 9367 4114 9376
TIME...MOT...LOC 2230Z 247DEG 31KT 4122 9352 

$$

Kotenberg

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at May 14, 2:25 PM CDT, 2 hours 36 minutes earlier.

Area forecast discussion, May 14, 2:25 PM CDT, 2 hours 36 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
225 PM CDT Thu May 14 2020

.SHORT TERM.../Tonight through Friday Night/
Issued at 225 PM CDT Thu May 14 2020

Confidence: Medium to High

Main concerns tonight will be the extent of the severe weather and
potential for training storms southeast as the boundary nears the
Iowa-Missouri border.  Front has managed to remain over southern
Iowa with most of the convection so far elevated along and just
north of the boundary.  Dewpoints have climbed to 65 to 70F in the
south with temperatures in the upper 60s/lower 70s as well.
Effective bulk shear continues to support some storm organization in
the south and LCL's remain low.  Early morning 12z subjective H850
analysis showed +10C fetch of moisture just ahead of the approaching
low. With clearing in the south now, expecting that severe will be
ramping up in the next few hours. SWODY1 has been trimmed back a bit
in the south.  As for the hydro threat, as noted in earlier update
we continue with dry antecedent conditions ove
r most of the region
but there is a small potential for a few rounds of storms southeast
into the overnight as the front sags south and low level inflow
increases into the overnight hours.  This would likely be focused
mainly in the far southeast where the current flash flood watch has
been issued.  The storms are likely to continue into the evening
hours and begin to diminish after midnight for most of the area.
Lows tonight will dip into the 40s northwest to the upper 50s in the
southeast. Friday will see a pleasant day with high pressure
building across the region.  Highs will reach the lower to mid 70s
during the day. Tomorrow night the next system will approach.  The
models are still slowing the timing and will follow suit with slower
arrival by 12z Saturday and mainly in southwest sections.  Lows
tomorrow night will hold in the lower to mid 50s south.

.LONG TERM.../Saturday through Thursday/
Issued at 225 PM CDT Thu May 14 2020

Confidence: Medium to High

Models in decent agreement for Saturday with incoming short wave and
potential for a spring system that bring another 1 or more inches of
rainfall to the region with breezy conditions.  Highs Saturday will
be slightly cooler in the upper 60s to lower 70s over the area with
thicker clouds and plenty of showers around. The system will pull
northeast overnight into Sunday, with another trough swinging
through the region. Showers and clouds along with continued
northwest flow.  Highs will fall back to the lower to mid 60s with
some sun returning later in the day. The advertised warm-up will
continue into midweek with highs returning to the 70s and 80s by
Wednesday into Thursday.  Little precipitation is expected for
Monday through Thursday.  Though the GFS is a bit faster by
Thursday, it's likely too fast and the Euro has a better handle on
timing which keeps the region dry into Thursday.

&&

.AVIATION.../For the 18Z TAFS through 18Z Friday afternoon/
Issued at 1227 PM CDT Thu May 14 2020

Area of convection continues to fester near the I80 corridor with
cigs still MVFR over portions of the north; some improvement there
by 21-00z. In the south, expecting the convection to increase
through 00z with occasional lower MVFR vis/cigs at KDSM/KOTM
through about 02-06z. Most areas improve toward 12z with less
restrictions to flight.  /rev

&&

.HYDROLOGY...
Issued at 225 PM CDT Thu May 14 2020

Confidence: Medium to High

Model trends continue to show some potential for localized heavy
rainfall in the far southeast late this afternoon and overnight.
Though somewhat conditional, have issued a Flash Flood Watch for a
small portion of the forecast area. Antecedent soil moisture and
conditions remain dry, but localized heavy rainfall in excess of 3
to 4 inches may cause some urban runoff issues if storms train
across the same locations.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Friday morning for IAZ086-097.

&&

SHORT TERM...REV
LONG TERM...REV
AVIATION...REV
HYDROLOGY...REV

Hazardous weather outlook, May 14, 12:34 PM CDT, 4 hours 27 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
1234 PM CDT Thu May 14 2020

IAZ086-097-151745-
Wapello-Davis-
1234 PM CDT Thu May 14 2020

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

A Flash Flood Watch is in effect for the area this evening and
overnight. Please refer to www.weather.gov/desmoines for more
information.

Strong to severe thunderstorms are expected later this afternoon
into this evening over portions of south central and southeastern
Iowa. Damaging wind gusts and large hail are the primary severe
concerns with an isolated tornado possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Thunderstorms return later Saturday into Saturday night, but the
severe weather threat looks low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed later today.

IAZ050-060>062-072>075-081>085-092>096-151745-
Tama-Polk-Jasper-Poweshiek-Madison-Warren-Marion-Mahaska-Adams-
Union-Clarke-Lucas-Monroe-Taylor-Ringgold-Decatur-Wayne-Appanoose-
1234 PM CDT Thu May 14 2020

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Strong to severe thunderstorms are expected later this afternoon
into this evening over portions of central, south central and
southeastern Iowa. Damaging wind gusts and large hail are the
primary severe concerns with an isolated tornado possible.
Locally heavy rainfall may also occur as well.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Thunderstorms return later Saturday into Saturday night, but the
severe weather threat looks low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed later today.

IAZ004>007-015>017-023>028-033>039-044>049-057>059-070-071-151745-
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-Audubon-Guthrie-Dallas-Cass-Adair-
1234 PM CDT Thu May 14 2020

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

A few thunderstorms remains possible later today with the higher
severe risk over south central and southeastern Iowa.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Thunderstorms return later Saturday into Saturday night, but the
severe weather threat looks low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed later today.

In the hours before

Special weather statement, May 14, 4:14 PM CDT, 47 minutes before

Special Weather Statement
National Weather Service Des Moines IA
414 PM CDT Thu May 14 2020

IAZ059-060-142215-
Polk IA-Dallas IA-
414 PM CDT Thu May 14 2020

...Strong storm to impact Des Moines Metro area...

At 414 PM CDT, Doppler radar was tracking a strong thunderstorm over
Adel, moving east at 30 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Des Moines, West Des Moines, Ankeny, Urbandale, Johnston, Clive,
Altoona, Waukee, Norwalk, Pleasant Hill, Grimes, Adel, Windsor
Heights, Carlisle, Polk City, Saylorville, Dallas Center, Granger, De
Soto and Van Meter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4169 9410 4185 9354 4152 9344 4150 9406
TIME...MOT...LOC 2114Z 259DEG 24KT 4161 9399

Kotenberg

Special weather statement, May 14, 4:28 PM CDT, 33 minutes before

Special Weather Statement
National Weather Service Des Moines IA
428 PM CDT Thu May 14 2020

IAZ072-073-142200-
Madison IA-Warren IA-
428 PM CDT Thu May 14 2020

...Small hail possible...

At 428 PM CDT, Doppler radar was tracking a strong thunderstorm near
Avenue Of The Saints Event Center, or 11 miles southeast of
Winterset, moving northeast at 40 mph.

Penny size hail will be possible with this storm.

Locations impacted include...
Avenue Of The Saints Event Center, St. Charles, Truro, Martensdale,
St. Marys and East Peru.

A Severe Thunderstorm Watch remains in effect until midnight CDT for
south central Iowa.

LAT...LON 4125 9397 4139 9371 4138 9366 4116 9387
      4116 9389
TIME...MOT...LOC 2128Z 242DEG 34KT 4124 9386

Kotenberg

Local storm report, May 14, 4:29 PM CDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
429 PM CDT THU MAY 14 2020

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

0418 PM     HAIL             1 W NEW VIRGINIA        41.18N 93.75W
05/14/2020  M1.75 INCH       WARREN             IA   TRAINED SPOTTER

&&

KLP

Local storm report, May 14, 4:41 PM CDT, 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
441 PM CDT THU MAY 14 2020

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

0430 PM     LIGHTNING        2 N GRIMES              41.71N 93.80W
05/14/2020                   POLK               IA   LAW ENFORCEMENT

            LIGHTNING STRIKE HIT A HOME.

&&

BF

Local storm report, May 14, 4:42 PM CDT, 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
442 PM CDT THU MAY 14 2020

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

0424 PM     HAIL             6 ENE NEW VIRGINIA      41.21N 93.63W
05/14/2020  E1.00 INCH       WARREN             IA   AMATEUR RADIO

            1.5 MILES NORTHWEST OF MEDORA, IOWA.

&&

KLP

Local storm report, May 14, 4:44 PM CDT, 17 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
444 PM CDT THU MAY 14 2020

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

0419 PM     HAIL             NEW VIRGINIA            41.19N 93.73W
05/14/2020  E1.25 INCH       WARREN             IA   TRAINED SPOTTER

&&

BF

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 14, 12:26 PM CDT	Flash Flood Watch	DMX	Davis, Wapello	11 hr
May 14, 2:36 PM CDT	Special Weather Statement	DMX	Guthrie	54 min
May 14, 3:35 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Dallas, Guthrie, Madison	40 min
May 14, 3:45 PM CDT	Special Weather Statement	DMX	Adair, Madison	45 min
May 14, 3:57 PM CDT	Special Weather Statement	DMX	Clarke, Madison, Marion, Warren	48 min
May 14, 4:08 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Madison, Warren	52 min
May 14, 4:14 PM CDT	Special Weather Statement	DMX	Dallas, Polk	61 min
May 14, 4:28 PM CDT	Special Weather Statement	DMX	Madison	32 min
May 14, 4:46 PM CDT	Tornado Warning	DMX	Clarke, Lucas, Marion, Warren	29 min
May 14, 5:14 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Marion, Monroe, Warren	46 min
May 14, 5:29 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Lucas, Marion, Warren	31 min
May 14, 5:44 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Lucas, Union, Warren	31 min
May 14, 5:57 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Marion, Monroe	48 min
May 14, 6:13 PM CDT	Special Weather Statement	DMX	Decatur, Monroe, Wapello, Wayne	62 min
May 14, 6:20 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Monroe, Wapello	40 min
May 14, 6:56 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Monroe, Wapello	49 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2020 Every severe thunderstorm warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.