Alert archive / Iowa / Tornado Warnings in 2017

Tornado Warning 6, NWS Sioux Falls, SD

May 17, 2017Sioux County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 17, 2017, 1:56 PM CDT for Sioux County, Iowa. It was in force for 34 min. 1 report 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: May 17, 2017, 1:56 PM CDT (18:56 UTC)
Expired: May 17, 2017, 2:30 PM CDT
In force: 34 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

County Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 81 km from the middle of the area, began a volume at 18:56 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
May 17, 2:10 PM CDT	TORNADO	3 Ne Alton, IA	TORNADO BRIEFLY TOUCHED THE GROUND.

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
May 17, 12:08 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 6.9 hours before the alert went out and 200 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: 121 J/kg
Mixed-layer CIN: -156 J/kg
Mixed-layer LCL: 1106 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 119 m²/s²
0-3 km storm-relative helicity: 132 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

668 
WFUS53 KFSD 171856
TORFSD
IAC167-171930-
/O.NEW.KFSD.TO.W.0006.170517T1856Z-170517T1930Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
156 PM CDT WED MAY 17 2017

The National Weather Service in Sioux Falls has issued a

* Tornado Warning for...
  Eastern Sioux County in northwestern Iowa...

* Until 230 PM CDT
    
* At 155 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Alton, or near Orange City, moving northwest at 25
  mph.

  HAZARD...Tornado and quarter 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...
  Hospers around 205 PM CDT. 
  Boyden and Matlock around 225 PM CDT. 
  Hull around 230 PM CDT. 

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.

&&

LAT...LON 4294 9600 4319 9624 4326 9601 4326 9593
      4309 9586 4297 9586
TIME...MOT...LOC 1855Z 156DEG 24KT 4301 9596 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

Ferguson

2 follow-up statements

596 
WWUS53 KFSD 171900
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
200 PM CDT WED MAY 17 2017

IAC167-171930-
/O.CON.KFSD.TO.W.0006.000000T0000Z-170517T1930Z/
Sioux IA-
200 PM CDT WED MAY 17 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 230 PM CDT FOR EASTERN
SIOUX COUNTY...
        
At 200 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Alton, or near Orange City, moving northwest at 30
mph.

HAZARD...Tornado and quarter size hail. 

SOURCE...Weather spotters reported a funnel cloud northeast of Alton 
         at 200 PM CDT.

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...
  Boyden around 220 PM CDT. 
  Matlock around 225 PM CDT. 
  Hull around 230 PM CDT. 

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.

&&

LAT...LON 4294 9600 4319 9624 4326 9601 4326 9593
      4309 9586 4297 9586
TIME...MOT...LOC 1900Z 156DEG 24KT 4304 9598 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

Ferguson

264 
WWUS53 KFSD 171909
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
209 PM CDT WED MAY 17 2017

IAC167-171930-
/O.CON.KFSD.TO.W.0006.000000T0000Z-170517T1930Z/
Sioux IA-
209 PM CDT WED MAY 17 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 230 PM CDT FOR EASTERN
SIOUX COUNTY...
    
At 209 PM CDT, a confirmed tornado was located west of Hospers, or 
near Orange City, moving northwest at 25 mph.

HAZARD...Damaging tornado and quarter size hail. 

SOURCE...Weather spotters confirmed tornado. 

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 tornado will be near...
  Boyden around 220 PM CDT. 
  Matlock around 225 PM CDT. 
  Hull around 230 PM CDT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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.

&&

LAT...LON 4294 9600 4319 9624 4326 9601 4326 9593
      4309 9586 4297 9586
TIME...MOT...LOC 1909Z 155DEG 24KT 4310 9602 

TORNADO...OBSERVED
HAIL...1.00IN

$$

Ferguson

The office that day

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

Issued	Product	Office	Counties	Lasted
May 16, 7:43 PM CDT	Severe Thunderstorm Warning	FSD	Ida	33 min
May 16, 8:22 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	23 min
May 17, 11:16 AM CDT	River Flood Warning	FSD	Clay	24 hr
May 17, 11:16 AM CDT	River Flood Warning	FSD	Buena Vista, Clay	24 hr
May 17, 11:16 AM CDT	River Flood Warning	FSD	Plymouth, Sioux	5 days
May 17, 11:16 AM CDT	River Flood Warning	FSD	Plymouth	6 days
May 17, 11:16 AM CDT	River Flood Warning	FSD	Clay	4 days
May 17, 11:16 AM CDT	River Flood Warning	FSD	Clay, Dickinson	59 hr
May 17, 1:33 PM CDT	Tornado Warning	FSD	Sioux	27 min
May 17, 2:03 PM CDT	Tornado Warning	FSD	Sioux	27 min
May 17, 2:28 PM CDT	Tornado Warning	FSD	Lyon, Sioux	32 min
May 17, 2:34 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	26 min
May 17, 3:01 PM CDT	Tornado Warning	FSD	Lyon	29 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.