Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 35, NWS Sioux Falls, SD

August 18, 20174 counties in Iowa

NWS Sioux Falls, SD issued this tornado warning at Aug 18, 2017, 8:54 PM CDT for 4 counties in Iowa. It was in force for 36 min. 5 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, 8:54 PM CDT (01:54 UTC)
Expired: Aug 18, 2017, 9:30 PM CDT
In force: 36 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.5 in

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, O'Brien County, IA

The radar

The Sioux Falls radar (KFSD), 124 km from the middle of the area, began a volume at 01:56 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, 8:56 PM CDT	HAIL 1	4 N Sutherland, IA	TIME ESTIMATED FROM RADAR.
Aug 18, 8:56 PM CDT	HAIL 1.25	3 Nnw Sutherland, IA	TIME ESTIMATED FROM RADAR.
Aug 18, 9:20 PM CDT	TSTM WND DMG	3 Ese Larrabee, IA	TWISTED TREES, CORN FLATTENED AROUND 3 MILES EAST, 1 MILE SOUTH OF LARRABEE. TIME ESTIMATED FROM RADAR.
Aug 18, 9:20 PM CDT	HAIL 1	5 Ene Larrabee, IA	TIME ESTIMATED FROM RADAR.
Aug 18, 9:21 PM CDT	TORNADO	3 Ese Larrabee, IA	DELAYED REPORT. EF0 TORNADO SURVEYED 3 ESE LARRABEE. TRAVELED 0.3 MILES WITH A PATH WIDTH OF 25 YARDS. MINOR CROP AND TREE DAMAGE. TORNADO LIFTED AT 9:27 PM.

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

Omaha, NE (KOAX), launched 00:00Z, 1.9 hours before the alert went out and 197 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: 1353 J/kg
Mixed-layer CIN: -118 J/kg
Mixed-layer LCL: 1673 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 30 m²/s²
0-3 km storm-relative helicity: 61 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.1

Open this sounding in Storm Lab

The text

As transmitted.

367 
WFUS53 KFSD 190154
TORFSD
IAC021-035-041-141-190230-
/O.NEW.KFSD.TO.W.0035.170819T0154Z-170819T0230Z/

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

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Northeastern Cherokee County in northwestern Iowa...
  Northwestern Buena Vista County in northwestern Iowa...
  Southwestern Clay County in northwestern Iowa...
  Southeastern O'Brien County in northwestern Iowa...

* Until 930 PM CDT
    
* At 854 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Sutherland, or 17 miles north of Cherokee, moving
  southeast at 30 mph.

  HAZARD...Tornado and ping pong 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...
  Peterson around 915 PM CDT. 
  Linn Grove around 920 PM CDT. 

Other locations impacted by this tornadic thunderstorm include
Calumet.

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.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Sioux Falls.

&&

LAT...LON 4304 9565 4314 9544 4284 9516 4272 9542
TIME...MOT...LOC 0154Z 320DEG 28KT 4300 9553 

TORNADO...RADAR INDICATED
HAIL...1.50IN

$$

Ferguson

1 follow-up statement

891 
WWUS53 KFSD 190206
SVSFSD

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

IAC021-035-041-141-190230-
/O.CON.KFSD.TO.W.0035.000000T0000Z-170819T0230Z/
Cherokee IA-Buena Vista IA-Clay IA-O'Brien IA-
906 PM CDT FRI AUG 18 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 930 PM CDT FOR
NORTHEASTERN CHEROKEE...NORTHWESTERN BUENA VISTA...SOUTHWESTERN CLAY
AND SOUTHEASTERN O'BRIEN COUNTIES...
    
At 906 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Sutherland, or 12 miles north of Cherokee, moving
southeast at 30 mph.

HAZARD...Tornado and ping pong 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...
  Peterson around 920 PM CDT. 

Other locations impacted by this tornadic thunderstorm include
Calumet.

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.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

If a tornado or other severe weather is experienced, report it to 
the National Weather Service or your local nearest law enforcement 
agency who will send your report. This act may save lives of others 
in the path of dangerous weather.

&&

LAT...LON 4297 9560 4308 9540 4284 9516 4272 9542
TIME...MOT...LOC 0206Z 321DEG 26KT 4293 9550 

TORNADO...RADAR INDICATED
HAIL...1.50IN

$$

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, 7:49 PM CDT	Tornado Warning	FSD	Osceola	26 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, 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

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.