Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 20, NWS Sioux Falls, SD

June 29, 2017Woodbury County, Iowa

NWS Sioux Falls, SD issued this tornado warning at Jun 29, 2017, 4:46 PM CDT for Woodbury 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: Jun 29, 2017, 4:46 PM CDT (21:46 UTC)
Expired: Jun 29, 2017, 5:15 PM CDT
In force: 29 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 2.75 in

County Woodbury County, IA

The radar

The Omaha radar (KOAX), 118 km from the middle of the area, began a volume at 21:48 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, 4:59 PM CDT	HAIL 1.25	Bronson, IA
Jun 29, 5:18 PM CDT	HAIL 1.75	8 Nne Hornick, IA

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

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, 9.8 hours before the alert went out and 118 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.

321 
WFUS53 KFSD 292146
TORFSD
IAC193-292215-
/O.NEW.KFSD.TO.W.0020.170629T2146Z-170629T2215Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
446 PM CDT THU JUN 29 2017

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Central Woodbury County in west central Iowa...

* Until 515 PM CDT
    
* At 446 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Sergeant Bluff, or 8 miles southeast of Sioux
  City, moving east at 15 mph.

  HAZARD...Tornado and baseball size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This tornadic thunderstorm will remain over mainly rural areas of
  central Woodbury County, including the following locations:
  Bronson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4233 9634 4246 9629 4246 9599 4227 9606
TIME...MOT...LOC 2146Z 285DEG 15KT 4240 9629 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

Weisser

2 follow-up statements

959 
WWUS53 KFSD 292157
SVSFSD

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

IAC193-292215-
/O.CON.KFSD.TO.W.0020.000000T0000Z-170629T2215Z/
Woodbury IA-
457 PM CDT THU JUN 29 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 PM CDT FOR CENTRAL
WOODBURY COUNTY...
        
At 457 PM CDT, a severe thunderstorm capable of producing a tornado
was located 7 miles northeast of Salix, or 14 miles southeast of 
Sioux City, moving east at 35 mph. 

Rotation has increased significantly south of Bronson!

HAZARD...Tornado and baseball size hail. 

SOURCE...Weather spotters reported a funnel cloud. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

Locations impacted include...
Bronson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4233 9634 4246 9629 4246 9599 4227 9606
TIME...MOT...LOC 2157Z 278DEG 30KT 4237 9618 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

Weisser

238 
WWUS53 KFSD 292212
SVSFSD

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

IAC193-292222-
/O.EXP.KFSD.TO.W.0020.000000T0000Z-170629T2215Z/
Woodbury IA-
512 PM CDT THU JUN 29 2017

...THE TORNADO WARNING FOR CENTRAL WOODBURY COUNTY WILL EXPIRE AT 515
PM CDT...
        
The storm which prompted the warning has moved out of the area.
Therefore the warning will be allowed to expire.  However gusty 
winds are still possible with this thunderstorm. A severe 
thunderstorm warning is in effect for eastern Woodbury county.

A severe thunderstorm watch remains in effect until 1100 PM CDT for
west central Iowa.

LAT...LON 4233 9634 4246 9629 4246 9599 4227 9606
TIME...MOT...LOC 2212Z 285DEG 15KT 4235 9610 

$$

Weisser

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, 4:47 PM CDT	Flash Flood Warning	FSD	Plymouth, Woodbury	3 hr
Jun 29, 4:54 PM CDT	Severe Thunderstorm Warning	FSD	Sioux	51 min
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

Tornado Warnings in Iowa, 2017 Every tornado warning in 2017 Tornadoes 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.