Alert archive / Iowa / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 74, NWS Des Moines, IA

May 29, 2018Audubon County, Cass County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 29, 2018, 5:15 PM CDT for Audubon County, Cass County, Iowa. It was in force for 45 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 29, 2018, 5:15 PM CDT (22:15 UTC)
Expired: May 29, 2018, 6:00 PM CDT
In force: 45 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Audubon County, IA, Cass County, IA

The radar

The Des Moines radar (KDMX), 112 km from the middle of the area, began a volume at 22:14 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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 29, 1:43 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.3 hours before the alert went out and 114 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: 1666 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 140 m²/s²
0-3 km storm-relative helicity: 153 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

723 
WUUS53 KDMX 292215
SVRDMX
IAC009-029-292300-
/O.NEW.KDMX.SV.W.0074.180529T2215Z-180529T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
515 PM CDT TUE MAY 29 2018

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northwestern Cass County in southwestern Iowa...
  South central Audubon County in west central Iowa...

* Until 600 PM CDT.

* At 515 PM CDT, a severe thunderstorm was located 7 miles east of
  Atlantic, moving northwest at 15 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...
  Atlantic, Anita, Lewis, Cumberland, Brayton, Marne, Wiota, Lake
  Anita State Park, Atlantic Municipal Airport and Anita Municipal
  Airport.

This includes Interstate 80 between mile markers 50 and 69.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4151 9514 4151 9504 4153 9504 4158 9481
      4143 9474 4127 9484 4123 9496 4124 9505
      4147 9516 4150 9515
TIME...MOT...LOC 2215Z 155DEG 11KT 4137 9487 

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

Lee

3 follow-up statements

968 
WWUS53 KDMX 292233
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
533 PM CDT TUE MAY 29 2018

IAC009-029-292300-
/O.CON.KDMX.SV.W.0074.000000T0000Z-180529T2300Z/
Cass IA-Audubon IA-
533 PM CDT TUE MAY 29 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM CDT
FOR NORTHERN CASS AND SOUTH CENTRAL AUDUBON COUNTIES...

At 533 PM CDT, a severe thunderstorm was located near Atlantic,
moving northwest at 20 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...
Atlantic, Anita, Brayton, Marne, Wiota, Lake Anita State Park,
Atlantic Municipal Airport and Anita Municipal Airport.

This includes Interstate 80 between mile markers 50 and 69.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4151 9514 4151 9504 4153 9504 4158 9481
      4143 9474 4132 9488 4133 9503 4144 9512
      4150 9515
TIME...MOT...LOC 2233Z 154DEG 16KT 4145 9492 

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

Lee

264 
WWUS53 KDMX 292243
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
543 PM CDT TUE MAY 29 2018

IAC009-029-292300-
/O.CON.KDMX.SV.W.0074.000000T0000Z-180529T2300Z/
Cass IA-Audubon IA-
543 PM CDT TUE MAY 29 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM CDT
FOR NORTH CENTRAL CASS AND SOUTH CENTRAL AUDUBON COUNTIES...

At 543 PM CDT, a severe thunderstorm was located 8 miles northeast of
Atlantic, moving north at 15 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...
Atlantic, Brayton and Wiota. 

This includes Interstate 80 between mile markers 55 and 67.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4158 9481 4143 9481 4139 9493 4142 9503
      4151 9507 4151 9504 4153 9504
TIME...MOT...LOC 2243Z 159DEG 14KT 4150 9494 

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

Lee

642 
WWUS53 KDMX 292252
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
552 PM CDT TUE MAY 29 2018

IAC009-029-292302-
/O.EXP.KDMX.SV.W.0074.000000T0000Z-180529T2300Z/
Cass IA-Audubon IA-
552 PM CDT TUE MAY 29 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL CASS AND SOUTH
CENTRAL AUDUBON COUNTIES WILL EXPIRE AT 600 PM CDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 800 PM CDT for
southwestern and west central Iowa.

LAT...LON 4158 9481 4143 9481 4139 9493 4142 9503
      4151 9507 4151 9504 4153 9504
TIME...MOT...LOC 2252Z 155DEG 11KT 4152 9495 

$$

Lee

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 29, 4:13 PM CDT, 1 hour 2 minutes earlier.

Area forecast discussion, May 29, 4:13 PM CDT, 1 hour 2 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
413 PM CDT Tue May 29 2018

.DISCUSSION.../Tonight through Tuesday/
Issued at 413 PM CDT Tue May 29 2018

Primary focus on current storms with a short wave lifting
northwest from the Alberto system and another shortwave
approaching from the west. Two areas of storms have developed in
response. Similar to Monday, large hail, damaging winds and a few
landspouts are all possible. Strong winds thus far have been more
prominent than Monday with 0-3km theta-e differences of 25-30K and
downdraft CAPE around 1500 J/kg. The two regions should converge
just west of Interstate 35 in a few hours and should be the focus
for a few stronger updrafts before the entire area then begins to
move to the east. Possible that zone could have locally heavy
rainfall before storms diminish. Another area of storms over
Nebraska and Kansas will move into western Iowa round midnight or
after in a weakened state.

Most of Wednesday should be dry though additional storms are
possible as the boundary moves across central Iowa as it moves
east in the afternoon. The best chance will be over the far
northeast by mid afternoon. Wednesday will finally be cooler with
highs only in the 80s! The upper ridge will build back into the
area Thursday and Friday with highs back into the upper 80s to mid
90s. The next strong upper level system will arrive Friday night
into early Saturday. This will bring additional thunderstorm
chances to the region. A few could be severe. This will bring
cooler and more seasonal temperatures to the area for the
weekend. More zonal flow arrives to begin next week and will bring
slightly warmer temperatures and a few spot chances for additional
thunderstorms.

&&

.AVIATION.../For the 18Z TAFS through 18Z Wednesday afternoon/
Issued at 1230 PM CDT Tue May 29 2018

Scattered thunderstorms possible again later this afternoon and
evening. The main risk with these storms will be local microbursts
and thunderstorm outflow winds. The predominant wind will be from
the southeast today then gradually transitioning to southwest on
Wednesday. Any MVFR or lower cigs and vsbys will be in vicinity of
thunderstorms otherwise VFR conditions are forecast.

&&

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

DISCUSSION...Donavon
AVIATION...Donavon

Hazardous weather outlook, May 29, 3:14 PM CDT, 2 hours 1 minute before

Hazardous Weather Outlook
National Weather Service Des Moines IA
314 PM CDT Tue May 29 2018

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-301100-
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-
314 PM CDT Tue May 29 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Scattered thunderstorms are expected this afternoon through the
evening, and at times overnight. Some of the storms this afternoon
and evening may be severe, mainly west of Interstate 35, with
strong winds and large hail the main threats.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Thunderstorm chances will persist on Wednesday, then return from
Friday night into Saturday. Severe weather may be possible at
times.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this afternoon and evening.

In the hours before

Local storm report, May 29, 3:47 PM CDT, 1 hour 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
347 PM CDT TUE MAY 29 2018

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

0338 PM     HAIL             NEVADA                  42.02N 93.45W
05/29/2018  E0.88 INCH       STORY              IA   PUBLIC

            VIA SOCIAL MEDIA.

&&

AK

Local storm report, May 29, 3:53 PM CDT, 1 hour 22 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
353 PM CDT TUE MAY 29 2018

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

0348 PM     TSTM WND DMG     NEVADA                  42.02N 93.45W
05/29/2018                   STORY              IA   PUBLIC

            SOCIAL MEDIA PICTURE OF BIG TREE LIMBS AT
            LEAST 3 INCHES IN DIAMETER IF NOT GREATER.

&&

AK

Local storm report, May 29, 3:58 PM CDT, 1 hour 17 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
358 PM CDT TUE MAY 29 2018

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

0350 PM     HAIL             5 WSW DOW CITY          41.89N 95.58W
05/29/2018  E0.88 INCH       CRAWFORD           IA   PUBLIC

            VIA SOCIAL MEDIA.

&&

AK

Local storm report, May 29, 4:39 PM CDT, 36 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
439 PM CDT TUE MAY 29 2018

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

0410 PM     TSTM WND DMG     1 NW AMES               42.04N 93.64W
05/29/2018                   STORY              IA   PUBLIC

            VIA SOCIAL MEDIA. 4" TREE LIMB DOWN. TREE
            ROTTEN IN THE CENTER. SEVERAL DISPLACED
            GARBAGE CANS AS WELL.

&&

AK

Local storm report, May 29, 5:14 PM CDT, 1 minute before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
514 PM CDT TUE MAY 29 2018

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

0514 PM     TSTM WND DMG     HUMESTON                40.86N 93.50W
05/29/2018                   WAYNE              IA   PUBLIC

            DELAYED REPORT: MULTIPLE TREE LIMBS DOWN, IN
            EXCESS OF 3 INCHES IN DIAMETER.

&&

AK

The office that day

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

Issued	Product	Office	Counties	Lasted
May 29, 3:30 PM CDT	Severe Thunderstorm Warning	DMX	Polk, Story	18 min
May 29, 3:36 PM CDT	Severe Thunderstorm Warning	DMX	Story	24 min
May 29, 3:49 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	41 min
May 29, 3:59 PM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Story	16 min
May 29, 5:26 PM CDT	Severe Thunderstorm Warning	DMX	Polk, Warren	34 min
May 29, 5:37 PM CDT	Severe Thunderstorm Warning	DMX	Polk	23 min
May 29, 6:00 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Guthrie, Madison	30 min
May 29, 6:12 PM CDT	Severe Thunderstorm Warning	DMX	Dallas	33 min
May 29, 6:14 PM CDT	Severe Thunderstorm Warning	DMX	Emmet, Palo Alto	46 min
May 29, 6:24 PM CDT	Severe Thunderstorm Warning	DMX	Worth	21 min
May 29, 6:50 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Story	15 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2018 Every severe thunderstorm warning in 2018

Sources

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