Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 31, NWS Sioux Falls, SD

August 18, 2017Osceola County, Iowa; Nobles County, Minnesota

NWS Sioux Falls, SD issued this tornado warning at Aug 18, 2017, 7:49 PM CDT for Osceola County, Iowa; Nobles County, Minnesota. It was in force for 26 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: Aug 18, 2017, 7:49 PM CDT (00:49 UTC)
Expired: Aug 18, 2017, 8:15 PM CDT
In force: 26 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.75 in

Counties Osceola County, IA, Nobles County, MN

The radar

The Sioux Falls radar (KFSD), 84 km from the middle of the area, began a volume at 00:48 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
Aug 18, 7:54 PM CDT	TSTM WND DMG	3 S Bigelow, IA	TRACTOR TRAILER OVERTURNED ON HIGHWAY 60.
Aug 18, 7:55 PM CDT	HAIL 2	Bigelow, MN

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
Aug 18, 4:51 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 0.8 hours before the alert went out and 227 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: 13 J/kg
Mixed-layer CIN: -140 J/kg
Mixed-layer LCL: 1494 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 53 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

910 
WFUS53 KFSD 190049
TORFSD
IAC143-MNC105-190115-
/O.NEW.KFSD.TO.W.0031.170819T0049Z-170819T0115Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
749 PM CDT FRI AUG 18 2017

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Northwestern Osceola County in northwestern Iowa...
  South central Nobles County in southwestern Minnesota...

* Until 815 PM CDT
    
* At 749 PM CDT, a severe thunderstorm capable of producing a tornado
  was located 7 miles south of Rushmore, or 7 miles north of Sibley,
  moving southeast at 20 mph.

  HAZARD...Tornado and golf ball 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 dangerous storm will be near...
  Ocheyedan around 815 PM CDT. 

Other locations impacted by this tornadic thunderstorm include
Bigelow.

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 4352 9581 4358 9566 4339 9551 4334 9568
TIME...MOT...LOC 0049Z 324DEG 17KT 4352 9574 

TORNADO...RADAR INDICATED
HAIL...1.75IN

$$

Ferguson

1 follow-up statement

239 
WWUS53 KFSD 190056
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
756 PM CDT FRI AUG 18 2017

IAC143-MNC105-190115-
/O.CON.KFSD.TO.W.0031.000000T0000Z-170819T0115Z/
Osceola IA-Nobles MN-
756 PM CDT FRI AUG 18 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 815 PM CDT FOR
NORTHWESTERN OSCEOLA AND SOUTH CENTRAL NOBLES COUNTIES...
    
At 756 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Bigelow, moving southeast at 25 mph.

HAZARD...Tornado and two inch 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 dangerous storm will be near...
  Ocheyedan around 810 PM CDT. 

Other locations impacted by this tornadic thunderstorm include
Bigelow.

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 4352 9581 4358 9566 4339 9551 4334 9568
TIME...MOT...LOC 0056Z 331DEG 23KT 4348 9570 

TORNADO...RADAR INDICATED
HAIL...2.00IN

$$

Ferguson

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 7:45 PM CDT	Severe Thunderstorm Warning	FSD	Osceola	30 min
Aug 18, 8:06 PM CDT	Tornado Warning	FSD	Clay, O'Brien, Osceola	24 min
Aug 18, 8:25 PM CDT	Tornado Warning Tornado observedConsiderable damage threat	FSD	Clay, O'Brien, Osceola	35 min
Aug 18, 8:37 PM CDT	Tornado Warning	FSD	Clay, O'Brien	23 min
Aug 18, 8:54 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien	36 min
Aug 18, 9:26 PM CDT	Tornado Warning	FSD	Buena Vista, Cherokee, O'Brien	34 min
Aug 18, 9:53 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Ida	37 min
Aug 18, 7:11 PM CDT	Severe Thunderstorm Warning	FSD	Nobles	34 min
Aug 18, 7:15 PM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson	30 min
Aug 18, 7:18 PM CDT	Tornado Warning	FSD	Nobles	27 min

Nearby

Tornado Warnings in Iowa, 2017 Tornado Warnings in Minnesota, 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.