Alert archive / Iowa / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 114, NWS Sioux Falls, SD

June 29, 2017Sioux County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jun 29, 2017, 4:54 PM CDT for Sioux County, Iowa. It was in force for 51 min. 4 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 29, 2017, 4:54 PM CDT (21:54 UTC)
Expired: Jun 29, 2017, 5:45 PM CDT
In force: 51 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

County Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 76 km from the middle of the area, began a volume at 21:54 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 29, 5:08 PM CDT	HAIL 1.25	Ireton, IA	HAIL IS COVERING THE GROUND.
Jun 29, 5:24 PM CDT	HAIL 1	Sioux Center, IA
Jun 29, 5:30 PM CDT	HAIL 1	Sioux Center, IA
Jun 29, 5:50 PM CDT	HAIL 1	1 S Boyden, IA	REPORT VIA SOCIAL MEDIA.

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 3 storm reports to this severe thunderstorm warning; the first came 14 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 29, 3:42 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 9.9 hours before the alert went out and 192 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: 712 J/kg
Mixed-layer CIN: -119 J/kg
Mixed-layer LCL: 1324 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -19 m²/s²
0-3 km storm-relative helicity: 9 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

946 
WUUS53 KFSD 292154
SVRFSD
IAC167-292245-
/O.NEW.KFSD.SV.W.0114.170629T2154Z-170629T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
454 PM CDT THU JUN 29 2017

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Central Sioux County in northwestern Iowa...

* Until 545 PM CDT

* At 452 PM CDT, a severe thunderstorm was located over Craig, or 8
  miles southeast of Hawarden, moving north at 30 mph.

  HAZARD...Ping pong ball size hail and 60 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           wind damage to roofs, siding, and trees. 

* This severe thunderstorm will be near, 
  Ireton around 500 PM CDT. 
  Maurice around 505 PM CDT. 
  Sioux Center around 520 PM CDT. 
  Rock Valley and Hull around 535 PM CDT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4291 9604 4291 9644 4323 9636 4323 9597
TIME...MOT...LOC 2152Z 199DEG 26KT 4292 9635 

HAIL...1.50IN
WIND...60MPH
 
$$

Weisser

1 follow-up statement

166 
WWUS53 KFSD 292216
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
516 PM CDT THU JUN 29 2017

IAC167-292245-
/O.CON.KFSD.SV.W.0114.000000T0000Z-170629T2245Z/
Sioux IA-
516 PM CDT THU JUN 29 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM CDT
FOR CENTRAL SIOUX COUNTY...

At 516 PM CDT, a severe thunderstorm was located near Ireton, or near
Sioux Center, moving northeast at 20 mph.

HAZARD...Ping pong ball size hail and 60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees. 

This severe storm will be near...
  Orange City around 535 PM CDT. 
  Sioux Center around 540 PM CDT. 
  Hull around 545 PM CDT. 

At 508 pm CDT...half dollar hail was reported in Ireton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4291 9604 4291 9644 4323 9636 4323 9597
TIME...MOT...LOC 2216Z 218DEG 17KT 4301 9625 

HAIL...1.50IN
WIND...60MPH
 
$$

Weisser

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 Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 29, 3:28 PM CDT, 1 hour 26 minutes earlier.

Area forecast discussion, Jun 29, 3:28 PM CDT, 1 hour 26 minutes before

Area Forecast Discussion
National Weather Service Sioux Falls SD
328 PM CDT Thu Jun 29 2017

.SHORT TERM...(This evening through Friday)
Issued at 327 PM CDT Thu Jun 29 2017

The main concern this afternoon and evening is the potential for
scattered strong to severe storms through late this evening. As of
19Z, WV satellite imagery shows a shortwave over central Dakota with
associated cold front just west of our forecast area, extending to
central Nebraska. A secondary wave over central Nebraska is pushing
a warm front north into the area, thus bringing more instability and
moisture. Isolated to scattered high-based showers will continue to
develop ahead of the warm front, located somewhere along Highway 20.
These storms could produce small hail and brief heavy rain.

The area of greatest concern is along the Missouri River Valley and
northwest Iowa. Towering cumulus clouds already building along the
cold front will be the spark for convection initiation, mainly after
3 pm. Steepening lapse rates of 7 to 8 C/km, and perpendicular
strong bulk shear vector to 50 knots will aid in the development of
organized supercells along and ahead the surface boundary. With 0-3
km bulk shear vector from 25-35 knots, and decent 0-1km EHI a
tornado or two cannot be ruled out. Thunderstorms will gradually
diminish from west to east in the nighttime.

Some lingering showers are expected on Friday, mainly east of I-29.
Partly cloudy skies will prevail on Friday with breezy northwesterly
winds. Areas east of I-29 could see isolated showers and
thunderstorms in the afternoon, with diurnal heating and the passage
of a weak shortwave. Highs will generally be in the 70s.

.LONG TERM...(Friday night through Thursday)
Issued at 327 PM CDT Thu Jun 29 2017

There could be a lingering shower or two across southwest Minnesota
through the morning hours on Friday, but the main player will be an
elevated boundary working through in the afternoon hours.  With
atmospheric lapse rates being near moist adiabatic and limited wind
shear, expect storms to remain non-severe.

High pressure will build into the region on Friday night and have
erred toward cooler guidance values. Should see warming trend
through the weekend with a warm front lifting toward the I-90
corridor Sunday evening. This boundary may serve as the focusing
mechanism for thunderstorms across northwest Iowa Sunday evening as
a series of short waves move through the area Sunday night into
Monday.

Storm chances are a bit more conditional on Monday as a stronger cap
looks to be in place.  Models suggest a fairly strong shortwave
moving across the Central Plains on Tuesday, but looks to be focused
well south of the forecast area.

Thereafter, upper level ridge builds across the western half of the
US, leading to warmer and potentially drier conditions.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1236 PM CDT Thu Jun 29 2017

VFR conditions will prevail through the TAF period, but low
ceilings (low to mid clouds) are possible later today. Scattered
showers and thunderstorms are expected this afternoon and evening;
becoming numerous after 00z mostly for KFSD, and KSUX sites. Thunderstorm
chances will slowly diminish from west to east in the overnight
hours. In addition, strong gusty winds to 45 mph are possible with
the storms.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

SHORT TERM...05
LONG TERM...BT
AVIATION...05

Hazardous weather outlook, Jun 29, 4:20 AM CDT, 12 hours 34 minutes before

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
420 AM CDT Thu Jun 29 2017

IAZ001>003-MNZ071-072-080-081-089-090-097-098-SDZ038>040-050-
052>068-300930-
Lyon IA-Osceola-Dickinson-Lincoln MN-Lyon MN-Murray-Cottonwood-
Nobles-Jackson-Pipestone-Rock-Beadle-Kingsbury-Brookings-Gregory-
Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-
McCook-Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Lincoln SD-
Bon Homme-
420 AM CDT Thu Jun 29 2017

This Hazardous Weather Outlook is for portions of northwest Iowa,
southwest Minnesota, central South Dakota, east central South
Dakota, south central South Dakota, and southeast South Dakota.

.DAY ONE...Today and Tonight

Isolated to scattered showers will spread across the area through
the early afternoon, and persist into tonight. Severe weather is
unlikely.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.

IAZ012>014-020>022-031-032-NEZ013-014-SDZ069>071-300930-
Sioux-O'Brien-Clay IA-Plymouth-Cherokee-Buena Vista-Woodbury-Ida-
Dixon-Dakota-Yankton-Clay SD-Union-
420 AM CDT Thu Jun 29 2017

This Hazardous Weather Outlook is for portions of northwest Iowa,
west central Iowa, northeast Nebraska, and southeast South
Dakota.

.DAY ONE...Today and Tonight

Scattered showers are expected to develop by this afternoon and
persist through tonight. A few severe storms will be possible,
mainly late afternoon through this evening, with hail up to the
size of quarters and wind gusts up to 60 mph.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated at this time.

In the hours before

Local storm report, Jun 29, 4:20 PM CDT, 34 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
420 PM CDT THU JUN 29 2017

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

0415 PM     HAIL             SIOUX CITY              42.50N 96.39W
06/29/2017  E0.88 INCH       WOODBURY           IA   TRAINED SPOTTER

&&

Local storm report, Jun 29, 4:25 PM CDT, 29 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
425 PM CDT THU JUN 29 2017

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

0422 PM     HAIL             SIOUX CITY              42.50N 96.39W
06/29/2017  E1.00 INCH       WOODBURY           IA   TRAINED SPOTTER

&&

Local storm report, Jun 29, 4:29 PM CDT, 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
429 PM CDT THU JUN 29 2017

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

0427 PM     HAIL             2 WSW SOUTH SIOUX CITY  42.46N 96.45W
06/29/2017  E1.25 INCH       DAKOTA             NE   TRAINED SPOTTER

            ALSO SEVERAL TREE BRANCHES DOWN.

&&

Local storm report, Jun 29, 4:34 PM CDT, 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
434 PM CDT THU JUN 29 2017

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

0430 PM     HAIL             2 N SERGEANT BLUFF      42.43N 96.36W
06/29/2017  E4.25 INCH       WOODBURY           IA   TRAINED SPOTTER

&&

Local storm report, Jun 29, 4:38 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
438 PM CDT THU JUN 29 2017

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

0430 PM     TSTM WND GST     1 SE SOUTH SIOUX CITY   42.46N 96.39W
06/29/2017  E65 MPH          DAKOTA             NE   TRAINED SPOTTER

&&

Local storm report, Jun 29, 4:49 PM CDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
449 PM CDT THU JUN 29 2017

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

0433 PM     TSTM WND GST     2 W SERGEANT BLUFF      42.40N 96.39W
06/29/2017  M60 MPH          WOODBURY           IA   ASOS

&&

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 29, 3:48 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Woodbury	42 min
Jun 29, 4:08 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth	52 min
Jun 29, 4:23 PM CDT	Tornado Warning	FSD	Woodbury	37 min
Jun 29, 4:26 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	49 min
Jun 29, 4:46 PM CDT	Tornado Warning	FSD	Woodbury	29 min
Jun 29, 4:47 PM CDT	Flash Flood Warning	FSD	Plymouth, Woodbury	3 hr
Jun 29, 5:10 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	35 min
Jun 29, 5:29 PM CDT	Severe Thunderstorm Warning	FSD	Clay	33 min
Jun 29, 5:30 PM CDT	Tornado Warning	FSD	Woodbury	30 min
Jun 29, 5:43 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	18 min
Jun 29, 5:59 PM CDT	Severe Thunderstorm Warning	FSD	Ida, Woodbury	22 min
Jun 29, 6:27 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	33 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.