Alert archive / Iowa / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 75, NWS Des Moines, IA

April 19, 2017Marshall County, Story County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 19, 2017, 10:18 PM CDT for Marshall County, Story County, Iowa. It was in force for 42 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: Apr 19, 2017, 10:18 PM CDT (03:18 UTC)
Expired: Apr 19, 2017, 11:00 PM CDT
In force: 42 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Marshall County, IA, Story County, IA

The radar

The Des Moines radar (KDMX), 62 km from the middle of the area, began a volume at 03:19 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
Apr 19, 8:57 PM CDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 3.3 hours before the alert went out and 220 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: 628 J/kg
Mixed-layer CIN: -86 J/kg
Mixed-layer LCL: 988 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 308 m²/s²
0-3 km storm-relative helicity: 522 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 6.1

Open this sounding in Storm Lab

The text

As transmitted.

243 
WUUS53 KDMX 200318
SVRDMX
IAC127-169-200400-
/O.NEW.KDMX.SV.W.0075.170420T0318Z-170420T0400Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
1018 PM CDT WED APR 19 2017

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  East central Story County in central Iowa...
  Central Marshall County in central Iowa...

* Until 1100 PM CDT.

* At 1018 PM CDT, a severe thunderstorm was located near Nevada,
  moving east at 50 mph.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is expected. 

* Locations impacted include...
  Marshalltown, Nevada, State Center, Colo, Albion, Liscomb, Clemons,
  Green Mountain, St. Anthony and Marshalltown Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4194 9322 4194 9332 4195 9344 4206 9347
      4221 9291 4221 9278 4214 9276 4202 9277
TIME...MOT...LOC 0318Z 249DEG 42KT 4201 9333 

HAIL...1.00IN
WIND...<50MPH
 
$$

Curtis

3 follow-up statements

148 
WWUS53 KDMX 200330
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1030 PM CDT WED APR 19 2017

IAC127-169-200400-
/O.CON.KDMX.SV.W.0075.000000T0000Z-170420T0400Z/
Story IA-Marshall IA-
1030 PM CDT WED APR 19 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1100 PM CDT
FOR EAST CENTRAL STORY AND NORTHERN MARSHALL COUNTIES...

At 1030 PM CDT, a severe thunderstorm was located near State Center,
or 12 miles west of Marshalltown, moving east at 50 mph.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Marshalltown, State Center, Albion, Liscomb, Clemons, Green Mountain,
St. Anthony and Marshalltown Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4201 9296 4198 9322 4212 9325 4221 9291
      4221 9278 4214 9276 4204 9277
TIME...MOT...LOC 0330Z 249DEG 42KT 4206 9315 

HAIL...1.00IN
WIND...<50MPH
 
$$

Curtis

204 
WWUS53 KDMX 200342
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1042 PM CDT WED APR 19 2017

IAC169-200352-
/O.CAN.KDMX.SV.W.0075.000000T0000Z-170420T0400Z/
Story IA-
1042 PM CDT WED APR 19 2017

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL STORY COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A severe thunderstorm watch remains in effect until 400 AM CDT for
central Iowa.

LAT...LON 4203 9294 4202 9309 4216 9309 4221 9291
      4221 9278 4214 9276 4204 9277
TIME...MOT...LOC 0342Z 249DEG 42KT 4211 9297 

$$

IAC127-200400-
/O.CON.KDMX.SV.W.0075.000000T0000Z-170420T0400Z/
Marshall IA-
1042 PM CDT WED APR 19 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1100 PM CDT
FOR NORTHEASTERN MARSHALL COUNTY...

At 1042 PM CDT, a severe thunderstorm was located near Marshalltown,
moving east at 50 mph.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Marshalltown, Albion, Liscomb, Green Mountain and Marshalltown
Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4203 9294 4202 9309 4216 9309 4221 9291
      4221 9278 4214 9276 4204 9277
TIME...MOT...LOC 0342Z 249DEG 42KT 4211 9297 

HAIL...1.00IN
WIND...<50MPH
 
$$

Curtis

022 
WWUS53 KDMX 200400
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1100 PM CDT WED APR 19 2017

IAC127-200409-
/O.EXP.KDMX.SV.W.0075.000000T0000Z-170420T0400Z/
Marshall IA-
1100 PM CDT WED APR 19 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN MARSHALL COUNTY
WILL EXPIRE AT 1100 PM CDT...
        
The storm which prompted the warning has moved out of the area.
Therefore the warning will be allowed to expire.

A severe thunderstorm watch remains in effect until 400 AM CDT for
central Iowa.

LAT...LON 4203 9294 4202 9309 4216 9309 4221 9291
      4221 9278 4214 9276 4204 9277
TIME...MOT...LOC 0359Z 249DEG 42KT 4218 9273 

$$

Curtis

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 Apr 19, 6:52 PM CDT, 3 hours 26 minutes earlier.

Area forecast discussion, Apr 19, 6:52 PM CDT, 3 hours 26 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
652 PM CDT Wed Apr 19 2017

.SHORT TERM.../Tonight through Thursday/
Issued at 315 PM CDT Wed Apr 19 2017

Early afternoon surface analysis places the warm front over far
southern Iowa along or south of Highway 34 with low pressure nearing
Concordia, KS. South of this boundary, dewpoints are in the low and
middle 60s with temperatures in the 70s. 19z operational and non-
operational visible satellite imagery shows cumulus clouds along
this boundary with stable wave clouds just north of the front up
towards Des Moines eroding. Over northern Iowa, the atmosphere is
relatively stable as clouds, showers, and thunderstorms are in the
process of exiting central Iowa as the warm front slowly trudges
northward. 19z SPC mesoanalysis shows SBCAPE values peaking near
2000 J/kg and bulk wind shear of 50 to 60 knots in the vicinity
of the warm front continue to favor supercell development. Steep
mid- level lapse rates east of the surface low into far southwest
Iowa will continue farther into the warm sector as the low
approaches and some mid-level cooling takes place. 0-1km SRH is
around 200 m2/s2 east of the surface low along the warm front
keeping the main tornado threat in this area, especially closer to
the surface low. Large hail will also be possible near and just
north of the warm front as storms cross the front and become
elevated.

Current thinking with the slow progress of the warm front is that it
may approach the Interstate 80 corridor by late this afternoon and
early this evening. Expect convective initiation around 4 or 5 this
afternoon in eastern Nebraska and western Iowa as the low nears the
state. A broken line of thunderstorms will develop along the cold
front that will move into southwest Iowa this evening with the
primary threat with these storms being large hail and damaging wind
gusts. Heavy rainfall will be possible, but the progressive nature
of the thunderstorms today should largely minimize the flash flood
threat. These storms should push through central Iowa (e.g. Des
Moines metro) mid-evening and be largely out our CWA by 9 to 10z.

For Thursday, cold air advection will occur as the low moves into
the Great Lakes with gusty winds from the northwest prevailing. Did
bump up winds a bit for tomorrow from initial guidance. Clouds will
gradually clear from southeast to northeast throughout the day.

.LONG TERM.../Thursday night through Wednesday/
Issued at 315 PM CDT Wed Apr 19 2017

Few concerns after system moves east tonight.  Temperatures will
cool off following the event with H850 temperatures from 2 to 4C
through Saturday during the daytime hours as high pressure builds
into the area and the storm track is displaced south during the
early portion of the extended. This will keep afternoon highs in the
50s to lower 60s over most of the region.  By Sunday low pressure
will be developing over the high plains with return southerly flow
across the region.  This will allow for H850 temperatures to climb
back to 6C to 7C for Sunday into Monday prior to a cold front
approaching from the west. This will result in afternoon highs back
in the 60s to lower 70s for at least a two day period. The front
should spark some showers and thunderstorms Monday night into
Tuesday.  A quick passage of the boundary will be followed by a
quick return to southerly flow with another southern stream short
wave and strong warm air advection back into the region with some
potential for showers and thunderstorms.  The majority of the area
will be far enough north of the better instability to see mainly
rain/showers and a fairly tight surface gradient resulting in a
breezy rainy period from late Tuesday night into Wednesday.
Depending on the timing the system may be just about out of the
region by Wednesday afternoon. There is a little more uncertainty
regarding afternoon highs Tuesday into Wednesday...depending on the
track of the system at that time...highs may be a bit cooler
especially if the low is just south enough to promote east northeast
surface flow over the area.  Much less diurnal range would be
anticipated. Some time to iron out the details in the next couple of
days.

&&

.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 652 PM CDT Wed Apr 19 2017

Overall main themes similar from previous issuance, just adjusted
timing a bit later with cold front taking its time moving into the
state. SHRA/TSRA likely at all sites through this evening into the
early morning hours. Low CIGS expected behind the front with winds
shifting around to the northwest and increasing during the day
Thursday.

&&

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

&&

SHORT TERM...Ansorge
LONG TERM...REV
AVIATION...Beerends

Hazardous weather outlook, Apr 19, 3:47 PM CDT, 6 hours 31 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
347 PM CDT Wed Apr 19 2017

IAZ016-017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-202100-
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-
347 PM CDT Wed Apr 19 2017

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Numerous strong to severe thunderstorms are forecast to develop
over western Iowa late this afternoon and move eastward this
evening and overnight. Large hail, damaging winds, and a few
tornadoes will be possible. The greatest threat for tornadoes will
be over southwest Iowa. Locally heavy rain is also possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters will likely be needed later this Wednesday afternoon and
evening. Reports of severe weather and rainfall amounts and their
impacts would be appreciated.

IAZ004>007-015-202100-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-
347 PM CDT Wed Apr 19 2017

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Periods of showers and thunderstorms are expected across the area
throughout the day into this evening. A few isolated severe
storms are possible with the main threat of hail and gusty winds.
The potential for locally heavy rain is also forecast through
tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed later this Wednesday afternoon and evening.
Reports of severe weather and rainfall amounts and their impacts
would be appreciated.

In the hours before

Local storm report, Apr 19, 8:39 PM CDT, 1 hour 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
839 PM CDT WED APR 19 2017

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

0800 PM     TORNADO          2 SW CARROLL            42.05N 94.89W
04/19/2017                   CARROLL            IA   STORM CHASER

            CHASER REPORTED A TORNADO TOUCHED DOWN JUST
            SW OF CARROLL. TREES DOWN AND DAMAGE TO A
            FEW OUT BUILDINGS. TIME RADAR ESTIMATED.

&&

Local storm report, Apr 19, 8:46 PM CDT, 1 hour 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
846 PM CDT WED APR 19 2017

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

0804 PM     TORNADO          2 SE CARROLL            42.05N 94.84W
04/19/2017                   CARROLL            IA   911 CALL CENTER

            CARROLL COUNTY DISPATCH RELAYED REPORTS OF
            MACHINE SHED WITH ROOF AND DOORS BLOWN OFF.

&&

Local storm report, Apr 19, 9:14 PM CDT, 1 hour 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
914 PM CDT WED APR 19 2017

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

0754 PM     TORNADO          HALBUR                  42.01N 94.97W
04/19/2017                   CARROLL            IA   TRAINED SPOTTER

            TRAINED SPOTTER REPORTED DAMAGE IN HALBUR,
            INCLUDING POWER LINES DOWN AND OVERTURNED
            CAMPER. TIME RADAR ESTIMATED.

&&

Local storm report, Apr 19, 9:34 PM CDT, 44 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
934 PM CDT WED APR 19 2017

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

0833 PM     TSTM WND GST     1 NNW SCRANTON          42.04N 94.55W
04/19/2017  E60 MPH          GREENE             IA   TRAINED SPOTTER

            PEA SIZE HAIL AND WATER PONDING IN THE
            STREETS AS WELL.

&&

MJB

Local storm report, Apr 19, 9:46 PM CDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
946 PM CDT WED APR 19 2017

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

0925 PM     TSTM WND GST     4 NE BOONE              42.09N 93.83W
04/19/2017  E60 MPH          BOONE              IA   PUBLIC

            SMALL TREE LIMBS DOWN.

&&

CM

Local storm report, Apr 19, 9:47 PM CDT, 31 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
947 PM CDT WED APR 19 2017

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

0925 PM     HAIL             4 NE BOONE              42.09N 93.83W
04/19/2017  E0.88 INCH       BOONE              IA   PUBLIC

&&

CM

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 19, 7:02 PM CDT	Special Weather Statement	DMX	Calhoun, Carroll, Crawford, Sac	43 min
Apr 19, 7:18 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	31 min
Apr 19, 7:37 PM CDT	Severe Thunderstorm Warning	DMX	Humboldt, Pocahontas, Webster	20 min
Apr 19, 7:37 PM CDT	Severe Thunderstorm Warning	DMX	Carroll	53 min
Apr 19, 7:56 PM CDT	Tornado Warning	DMX	Calhoun, Carroll, Greene	34 min
Apr 19, 8:14 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll, Greene, Guthrie	46 min
Apr 19, 8:22 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Webster	38 min
Apr 19, 8:29 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Greene, Webster	46 min
Apr 19, 8:45 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Cass	25 min
Apr 19, 9:58 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Madison	47 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2017 Every severe thunderstorm warning in 2017

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.