Alert archive / South Dakota / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 79, NWS Sioux Falls, SD

May 21, 2011Lyon County, Iowa; Lincoln County, Union County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 21, 2011, 7:49 PM CDT for Lyon County, Iowa; Lincoln County, Union County, South Dakota. 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: May 21, 2011, 7:49 PM CDT (00:49 UTC)
Expired: May 21, 2011, 8:15 PM CDT
In force: 26 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 58.0 mph

Counties Lyon County, IA, Lincoln County, SD, Union County, SD

The radar

The Sioux Falls radar (KFSD), 44 km from the middle of the area, began a volume at 00:50 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 21, 7:50 PM CDT	TSTM WND GST 60	7 Ene Beresford, SD	WIND MOVED SEVERAL FULL HEAVY FLOWER POTS. SMALL BRANCHES BLOWN FROM TREES. ALSO PEA SIZE HAIL.
May 21, 8:00 PM CDT	TSTM WND GST 60	Canton, SD	POWER POLE PARTLY BLOWN DOWN, POWER OUTAGE.

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 21, 2:25 PM CDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.8 hours before the alert went out and 211 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: 1436 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 1205 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 99 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

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

497 
WUUS53 KFSD 220049
SVRFSD
IAC119-SDC083-127-220115-
/O.NEW.KFSD.SV.W.0079.110522T0049Z-110522T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
749 PM CDT SAT MAY 21 2011

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN LYON COUNTY IN NORTHWEST IOWA...
  EASTERN LINCOLN COUNTY IN SOUTHEAST SOUTH DAKOTA...
  NORTHEASTERN UNION COUNTY IN SOUTHEAST SOUTH DAKOTA...

* UNTIL 815 PM CDT

* AT 749 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING HALF DOLLAR
  SIZE HAIL.  THIS STORM WAS LOCATED NEAR ALCESTER...OR 7 MILES EAST
  OF BERESFORD...AND MOVING NORTH AT 50 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  NEWTON HILLS STATE PARK AROUND 800 PM CDT...
  CANTON AROUND 805 PM CDT...
  WORTHING AROUND 810 PM CDT...
  HARRISBURG AROUND 815 PM 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 4299 9673 4344 9680 4343 9647 4326 9649
      4326 9655 4325 9656 4324 9657 4323 9656
      4322 9650 4298 9652
TIME...MOT...LOC 0049Z 182DEG 43KT 4310 9665
WIND...HAIL <58MPH 1.25IN

$$

HANKO

1 follow-up statement

564 
WWUS53 KFSD 220103
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
803 PM CDT SAT MAY 21 2011

SDC127-220112-
/O.CAN.KFSD.SV.W.0079.000000T0000Z-110522T0115Z/
UNION SD-
803 PM CDT SAT MAY 21 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN UNION COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED 
AREA.

LAT...LON 4313 9676 4322 9676 4344 9680 4343 9647
      4326 9649 4326 9655 4323 9657 4323 9656
      4322 9650 4315 9651
TIME...MOT...LOC 0102Z 180DEG 41KT 4322 9665

$$

IAC119-SDC083-220115-
/O.CON.KFSD.SV.W.0079.000000T0000Z-110522T0115Z/
LYON IA-LINCOLN SD-
803 PM CDT SAT MAY 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR CENTRAL
LINCOLN AND SOUTHWESTERN LYON COUNTIES UNTIL 815 PM CDT...

AT 802 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A SEVERE
THUNDERSTORM PRODUCING QUARTER SIZE HAIL...AND DAMAGING WINDS IN
EXCESS OF 60 MPH.  THIS STORM WAS LOCATED 5 MILES SOUTHWEST OF NEWTON
HILLS STATE PARK...OR 9 MILES NORTHEAST OF BERESFORD...MOVING NORTH
AT 45 MPH.

IN ADDITION...AT 750 PM A 60 MPH WIND GUST WAS REPORTED IN 7 MILES 
EAST NORTHEAST OF BERESFORD WITH THIS STORM.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  CANTON AND WORTHING AROUND 810 PM CDT...
  HARRISBURG AROUND 815 PM 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 4313 9676 4322 9676 4344 9680 4343 9647
      4326 9649 4326 9655 4323 9657 4323 9656
      4322 9650 4315 9651
TIME...MOT...LOC 0102Z 180DEG 41KT 4322 9665
WIND...HAIL 60MPH 1.00IN

$$

HANKO

The office that day

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

Issued	Product	Office	Counties	Lasted
May 21, 8:16 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	29 min
May 21, 7:05 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Turner	25 min
May 21, 7:28 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Lincoln, Turner	32 min
May 21, 7:38 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Union	37 min
May 21, 8:39 PM CDT	Severe Thunderstorm Warning	FSD	Minnehaha, Moody	36 min
May 22, 10:52 AM CDT	River Flood Warning	FSD	Minnehaha, Moody	22 hr

Nearby

Severe Thunderstorm Warnings in South Dakota, 2011 Severe Thunderstorm Warnings in Iowa, 2011 Every severe thunderstorm warning in 2011

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.