Alert archive / Iowa / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 98, NWS Des Moines, IA

June 6, 2018Jasper County, Polk County, Story County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 6, 2018, 5:19 PM CDT for Jasper County, Polk County, Story County, Iowa. It was in force for 41 min. 11 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: Jun 6, 2018, 5:19 PM CDT (22:19 UTC)
Expired: Jun 6, 2018, 6:00 PM CDT
In force: 41 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Jasper County, IA, Polk County, IA, Story County, IA

The radar

The Des Moines radar (KDMX), 33 km from the middle of the area, began a volume at 22:17 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
Jun 6, 5:29 PM CDT	HAIL 1.5	2 N Ames, IA	VIA SOCIAL MEDIA.
Jun 6, 5:30 PM CDT	TSTM WND DMG	1 Se Ames, IA	LARGE TREE LIMB DOWN.
Jun 6, 5:30 PM CDT	HAIL 1	1 Wsw Ames, IA	FEW TREE LIMBS REPORTED DOWN AS WELL.
Jun 6, 5:32 PM CDT	TSTM WND GST 71	2 S Ames, IA
Jun 6, 5:33 PM CDT	TSTM WND DMG	1 Wnw Ames, IA	REPORTS OF TREE DAMAGE ON THE IOWA STATE UNIVERSITY CAMPUS NEAR OSBORN DRIVE AND BESSEY HALL.
Jun 6, 5:33 PM CDT	TSTM WND DMG	2 W Ames, IA	CORRECTED TO THUNDERSTORM WIND DAMAGE. TREE DOWN ALONG HYLAND DRIVE JUST WEST OF IOWA STATE UNIVERSITY CAMPUS. TIME ESTIMATED.
Jun 6, 5:33 PM CDT	NON-TSTM WND DMG	2 W Ames, IA	TREE DOWN ALONG HYLAND DRIVE JUST WEST OF IOWA STATE UNIVERSITY CAMPUS. TIME ESTIMATED.
Jun 6, 5:39 PM CDT	HAIL 1	1 Nnw Ames, IA	DIME TO QUARTER SIZED HAIL. NUMEROUS 2-3 INCH BRANCHES DOWN IN NEIGHBORHOOD.
Jun 6, 5:39 PM CDT	HAIL 1.5	3 Ssw Gilbert, IA	TIME ESTIMATED.
Jun 6, 5:42 PM CDT	HAIL 1	1 Se Ames, IA	HAIL HAS BEEN ONGOING FOR AT LEAST 10 MIN.
Jun 6, 5:49 PM CDT	TSTM WND DMG	Nevada, IA	8 INCH TREE LIMB DOWN FROM AN OLD TREE BETWEEN THE 900-1100 BLOCK OF M AVENUE IN NEVADA.

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 10 storm reports to this severe thunderstorm warning; the first came 10 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
Jun 6, 3:23 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 10.3 hours before the alert went out and 244 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: 1624 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 256 m²/s²
0-3 km storm-relative helicity: 289 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

909 
WUUS53 KDMX 062219
SVRDMX
IAC099-153-169-062300-
/O.NEW.KDMX.SV.W.0098.180606T2219Z-180606T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
519 PM CDT WED JUN 6 2018

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northeastern Polk County in central Iowa...
  Story County in central Iowa...
  Northwestern Jasper County in central Iowa...

* Until 600 PM CDT.

* At 519 PM CDT, a severe thunderstorm was located near Nevada,
  moving southeast at 30 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...
  Ames, Ankeny, Nevada, Huxley, Slater, Gilbert, Iowa State Center,
  Maxwell, Colo, Cambridge, Elkhart, Collins, Alleman, Sheldahl,
  Kelley, Mingo and Ames Municipal Airport.

This includes Interstate 35 between mile markers 94 and 120.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4173 9325 4174 9366 4187 9369 4218 9370
      4218 9369 4209 9346 4203 9323 4186 9323
      4186 9322 4180 9322
TIME...MOT...LOC 2219Z 317DEG 24KT 4195 9350 

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

Beerends

2 follow-up statements

738 
WWUS53 KDMX 062228
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
528 PM CDT WED JUN 6 2018

IAC099-153-169-062300-
/O.CON.KDMX.SV.W.0098.000000T0000Z-180606T2300Z/
Polk IA-Story IA-Jasper IA-
528 PM CDT WED JUN 6 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM CDT
FOR NORTHEASTERN POLK...STORY AND NORTHWESTERN JASPER COUNTIES...

At 527 PM CDT, a severe thunderstorm was located over Huxley, or 8
miles southwest of Nevada, moving south at 25 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...
Ames, Ankeny, Nevada, Huxley, Slater, Gilbert, Iowa State Center,
Maxwell, Colo, Cambridge, Elkhart, Collins, Alleman, Sheldahl,
Kelley, Mingo and Ames Municipal Airport.

This includes Interstate 35 between mile markers 94 and 120.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4173 9325 4174 9366 4187 9369 4212 9370
      4217 9369 4209 9346 4203 9323 4186 9323
      4186 9322 4180 9322
TIME...MOT...LOC 2227Z 359DEG 23KT 4191 9355 

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

Beerends

863 
WWUS53 KDMX 062245
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
545 PM CDT WED JUN 6 2018

IAC099-153-169-062300-
/O.CON.KDMX.SV.W.0098.000000T0000Z-180606T2300Z/
Polk IA-Story IA-Jasper IA-
545 PM CDT WED JUN 6 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM CDT
FOR NORTHEASTERN POLK...SOUTHERN STORY AND NORTHWESTERN JASPER
COUNTIES...

At 545 PM CDT, a severe thunderstorm was located near Huxley, or 9
miles northeast of Ankeny, moving south 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...
Ames, Ankeny, Nevada, Huxley, Slater, Iowa State Center, Maxwell,
Colo, Cambridge, Elkhart, Collins, Alleman, Sheldahl, Kelley, Mingo
and Ames Municipal Airport.

This includes Interstate 35 between mile markers 94 and 116.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4173 9325 4174 9366 4187 9369 4206 9370
      4207 9357 4206 9339 4200 9323 4186 9323
      4186 9322 4180 9322
TIME...MOT...LOC 2245Z 347DEG 19KT 4183 9350 

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

Beerends

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 Jun 6, 2:54 PM CDT, 2 hours 25 minutes earlier.

Area forecast discussion, Jun 6, 2:54 PM CDT, 2 hours 25 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
254 PM CDT Wed Jun 6 2018

.DISCUSSION.../Tonight through Wednesday/
Issued at 253 PM CDT Wed Jun 6 2018

Iowa is just downstream of the upper ridge axis across the Plains in
an area of good warm advection and moisture advection.  Strong
instability has developed into the western half of Iowa this
afternoon as temperatures and dewpoints have quickly risen. Surface
boundary is pushing into northern Iowa with a weak shortwave
crossing through South Dakota along with some associated forcing.
This setup is the main concern in the short term with the potential
for severe convection late this afternoon into tonight. Latest GOES-
16 visible imagery is showing agitated cumulus near Storm Lake
and cap is likely to break within an hour or two as the updrafts
continue to strengthen and the front approaches. Given the strong
instability, rapid development is expected once initiation occurs.
However, shear is modest at best with effective bulk shear around
25- 35kts across much of the area. Despite this lack of stronger
shear, the strong instability should be more than sufficient for
severe hail production. Downdraft CAPES are also robust with
values of 1200-1400 adding the wind threat component as well. Any
tornado potential is likely to be early in the event with initial
strong updrafts stretching out any available surface vorticity
near the boundary. As gusts fronts consolidate into the evening,
the system is likely to become a forward propagating line moving
southeast through central into southern Iowa during the evening
with hail and winds the main threat. Heavy rains will also occur
given PWATs approaching 1.5 inches although as the system become
more progressive, the overall threat for flash flooding is
expected to remain limited, although urban areas are always
concerning in high rate events.

This convective complex is expected to pass out of southern Iowa
this evening.  However, main low level flow will continue to be
focused just west of the forecast area in Nebraska as southeast
South Dakota overnight with convection continuing in those
locations.  Upper flow will likely carry some of this convection
into western areas overnight with additional rainfall and some
limited severe threat persisting through sunrise.

Another round of convection is expected from later Thursday
afternoon into Friday morning as a shortwave passes through the
Plains and toward the state.  There remains the potential for severe
weather during this time along with heavy rain although detail
remain somewhat sketchy as the convection tonight into early
Thursday will impact Thursday afternoons outcome.  The potential for
additional periods of convection persist into the weekend and
especially later Monday into Monday night as the main shortwave
passes through the state.  Temperatures will be at the mercy of
convection, although with no push of colder air until early next
week, readings will remain mostly above normal.

&&

.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1235 PM CDT Wed Jun 6 2018

Morning convection has waned and focus is now on redevelopment
this afternoon, likely toward 21z along or south of Highway 20.
Storms will then propagate southeast or south with uncertainty
still around on exact timing and impacts, but likely will be
gusty and variable winds and restrictions to visibility and
ceilings. These storms should exit the area later this evening,
but may see new storms approach from the west after 6z, which is
not currently reflected in the official TAFs with low confidence.

&&

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

&&

DISCUSSION...Cogil
AVIATION...Ansorge

Hazardous weather outlook, Jun 6, 3:29 PM CDT, 1 hour 50 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
329 PM CDT Wed Jun 6 2018

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-072030-
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-
329 PM CDT Wed Jun 6 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...This afternoon and tonight

Scattered strong to severe thunderstorms are developing this
afternoon and will continue into tonight. The main threats will
be damaging thunderstorm wind gusts, large hail, and heavy rain.
An isolated tornado or two is also possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

An active weather pattern will continue into the weekend. A few
severe storms are possible on Thursday and Friday with the main
threat expected to be hail and winds. The heavy rain potential
also exists Thursday.

.SPOTTER INFORMATION STATEMENT...

Spotters might be needed this afternoon into tonight and at times
Thursday into this weekend.

Ansorge

In the hours before

Local storm report, Jun 6, 4:52 PM CDT, 27 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
452 PM CDT WED JUN 6 2018

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

0444 PM     HAIL             3 W LOHRVILLE           42.27N 94.61W
06/06/2018  E1.00 INCH       CALHOUN            IA   TRAINED SPOTTER

            VIA SPOTTERNETWORK.

&&

ANSORGE

Local storm report, Jun 6, 4:53 PM CDT, 26 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
453 PM CDT WED JUN 6 2018

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

0445 PM     HAIL             JEWELL                  42.31N 93.64W
06/06/2018  E1.75 INCH       HAMILTON           IA   TRAINED SPOTTER

&&

ANSORGE

Local storm report, Jun 6, 4:56 PM CDT, 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
456 PM CDT WED JUN 6 2018

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

0452 PM     HAIL             1 E BOONE               42.05N 93.86W
06/06/2018  E0.25 INCH       BOONE              IA   TRAINED SPOTTER

&&

Local storm report, Jun 6, 5:11 PM CDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
511 PM CDT WED JUN 6 2018

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

0504 PM     HAIL             TRAER                   42.19N 92.46W
06/06/2018  E2.00 INCH       TAMA               IA   BROADCAST MEDIA

            VIA KWWL-TV VIEWER.

&&

ANSORGE

Local storm report, Jun 6, 5:15 PM CDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
515 PM CDT WED JUN 6 2018

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

0514 PM     HAIL             GILBERT                 42.11N 93.65W
06/06/2018  E0.75 INCH       STORY              IA   TRAINED SPOTTER

&&

Local storm report, Jun 6, 5:18 PM CDT, 1 minute before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
518 PM CDT WED JUN 6 2018

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

0508 PM     HAIL             4 E BOONE               42.05N 93.80W
06/06/2018  E1.00 INCH       BOONE              IA   PUBLIC

            GENERALLY QUARTER SIZED HAIL FALLING IN THE
            LAST 5 MINUTES. VIA SOCIAL MEDIA.

&&

ANSORGE

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 6, 4:59 AM CDT	Special Weather Statement	DMX	Emmet, Palo Alto	61 min
Jun 6, 6:10 AM CDT	Special Weather Statement	DMX	Humboldt, Pocahontas	65 min
Jun 6, 7:10 AM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Pocahontas, Webster	50 min
Jun 6, 9:16 AM CDT	Special Weather Statement	DMX	Wright	59 min
Jun 6, 9:33 AM CDT	Special Weather Statement	DMX	Humboldt	27 min
Jun 6, 10:02 AM CDT	Special Weather Statement	DMX	Hamilton	43 min
Jun 6, 10:30 AM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Pocahontas	15 min
Jun 6, 3:19 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Pocahontas	41 min
Jun 6, 3:29 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Webster	46 min
Jun 6, 3:50 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun	40 min
Jun 6, 3:51 PM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Webster	54 min
Jun 6, 4:15 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Story, Webster	45 min
Jun 6, 4:19 PM CDT	Severe Thunderstorm Warning	DMX	Wright	33 min
Jun 6, 4:22 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Carroll, Greene	38 min
Jun 6, 4:34 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Grundy, Tama	41 min
Jun 6, 4:40 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Greene, Hamilton, Story	50 min
Jun 6, 4:47 PM CDT	Severe Thunderstorm Warning	DMX	Hardin, Marshall, Story	43 min
Jun 6, 4:59 PM CDT	Severe Thunderstorm Warning	DMX	Carroll, Crawford, Greene	46 min
Jun 6, 5:00 PM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Story	48 min
Jun 6, 5:14 PM CDT	Severe Thunderstorm Warning	DMX	Tama	61 min
Jun 6, 5:25 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas, Polk	35 min
Jun 6, 5:28 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin, Marshall, Story, Tama	47 min
Jun 6, 5:36 PM CDT	Severe Thunderstorm Warning	DMX	Polk	39 min
Jun 6, 5:39 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Greene, Guthrie	66 min
Jun 6, 5:43 PM CDT	Severe Thunderstorm Warning	DMX	Carroll, Crawford	47 min
Jun 6, 5:47 PM CDT	Severe Thunderstorm Warning	DMX	Marshall, Tama	58 min
Jun 6, 5:57 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas, Greene, Guthrie, Polk	63 min
Jun 6, 6:07 PM CDT	Severe Thunderstorm Warning	DMX	Polk	53 min
Jun 6, 6:08 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Tama	37 min
Jun 6, 6:29 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll, Crawford	36 min
Jun 6, 6:39 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	81 min
Jun 6, 6:43 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion, Poweshiek	62 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.