Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 101, NWS Sioux Falls, SD

May 6, 2012Plymouth County, Sioux County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 6, 2012, 1:55 AM CDT for Plymouth County, Sioux County, Iowa. It was in force for 35 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 6, 2012, 1:55 AM CDT (06:55 UTC)
Expired: May 6, 2012, 2:30 AM CDT
In force: 35 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Plymouth County, IA, Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 59 km from the middle of the area, began a volume at 06:56 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 6, 2:15 AM CDT	TSTM WND DMG	1 N Ireton, IA	DAMAGE TO FARM SHED AND SOME BRANCHES DOWN

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 5, 10:03 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 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: 2892 J/kg
Mixed-layer CIN: -51 J/kg
Mixed-layer LCL: 1936 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 6.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

857 
WUUS53 KFSD 060655
SVRFSD
IAC149-167-060730-
/O.NEW.KFSD.SV.W.0101.120506T0655Z-120506T0730Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
155 AM CDT SUN MAY 6 2012

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWESTERN PLYMOUTH COUNTY IN NORTHWEST IOWA...
  SIOUX COUNTY IN NORTHWEST IOWA...

* UNTIL 230 AM CDT

* AT 156 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED
  ALONG A LINE EXTENDING FROM NEWTON HILLS STATE PARK TO 5 MILES
  SOUTHEAST OF HAWARDEN...AND MOVING EAST AT 45 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  STRUBLE AND ROCK VALLEY AROUND 205 AM CDT...
  SIOUX CENTER AND MAURICE AROUND 210 AM CDT...
  ORANGE CITY AND HULL AROUND 215 AM CDT...
  ALTON AROUND 220 AM CDT...
  BOYDEN AROUND 225 AM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4305 9650 4307 9646 4310 9646 4312 9643
      4315 9647 4322 9647 4323 9654 4324 9654
      4326 9635 4326 9597 4290 9587 4284 9646
TIME...MOT...LOC 0656Z 251DEG 40KT 4325 9648 4296 9637
WIND...HAIL 60MPH <1.00IN

$$

CJ

2 follow-up statements

373 
WWUS53 KFSD 060715
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
215 AM CDT SUN MAY 6 2012

IAC149-167-060730-
/O.CON.KFSD.SV.W.0101.000000T0000Z-120506T0730Z/
SIOUX IA-PLYMOUTH IA-
215 AM CDT SUN MAY 6 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHEASTERN
PLYMOUTH AND SIOUX COUNTIES UNTIL 230 AM CDT...

AT 215 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
FROM ROCK VALLEY TO STRUBLE...MOVING EAST AT 45 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  SIOUX CENTER AND HULL AROUND 220 AM CDT...
  ORANGE CITY AND ALTON AROUND 225 AM CDT...
  BOYDEN AROUND 230 AM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4304 9639 4307 9637 4309 9641 4316 9645
      4322 9645 4323 9654 4326 9635 4326 9597
      4290 9587 4287 9631
TIME...MOT...LOC 0715Z 251DEG 40KT 4324 9626 4289 9615
WIND...HAIL 60MPH <1.00IN

$$

CJ

364 
WWUS53 KFSD 060730
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
230 AM CDT SUN MAY 6 2012

IAC149-167-060740-
/O.EXP.KFSD.SV.W.0101.000000T0000Z-120506T0730Z/
SIOUX IA-PLYMOUTH IA-
230 AM CDT SUN MAY 6 2012

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN PLYMOUTH AND
SIOUX COUNTIES HAS EXPIRED...

THE LINE OF STORMS WHICH PROMPTED THE WARNING HAVE WEAKENED BELOW
SEVERE LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR 
PROPERTY...HOWEVER SMALL HAIL AND WIND GUSTS TO 50 MPH ARE STILL 
POSSIBLE WITH THESE THUNDERSTORMS.

LAT...LON 4304 9639 4307 9637 4309 9641 4316 9645
      4322 9645 4323 9654 4326 9635 4326 9597
      4290 9587 4287 9631
TIME...MOT...LOC 0715Z 251DEG 40KT 4324 9626 4289 9615

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
May 6, 3:27 AM CDT	Severe Thunderstorm Warning	FSD	Clay	20 min
May 6, 4:45 AM CDT	River Flood Warning	FSD	Lyon	4 days
May 6, 4:45 AM CDT	River Flood Warning	FSD	Sioux	7 days
May 6, 4:45 AM CDT	River Flood Warning	FSD	Plymouth	7 days
May 6, 10:31 AM CDT	River Flood Warning	FSD	Lyon	60 hr
May 6, 10:31 AM CDT	River Flood Warning	FSD	Clay	29 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2012 Every severe thunderstorm warning in 2012

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.