Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 102, NWS Sioux Falls, SD

May 6, 2012Clay County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 6, 2012, 3:27 AM CDT for Clay County, Iowa. It was in force for 20 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 6, 2012, 3:27 AM CDT (08:27 UTC)
Expired: May 6, 2012, 3:47 AM CDT
In force: 20 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 58.0 mph

County Clay County, IA

The radar

The Sioux Falls radar (KFSD), 155 km from the middle of the area, began a volume at 08:29 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.

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, 8.5 hours before the alert went out and 221 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.

516 
WUUS53 KFSD 060827
SVRFSD
IAC041-060900-
/O.NEW.KFSD.SV.W.0102.120506T0827Z-120506T0900Z/

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

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN CLAY COUNTY IN NORTHWEST IOWA...

* UNTIL 400 AM CDT

* AT 328 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
  TRACKING A SEVERE THUNDERSTORM CAPABLE OF PRODUCING HALF DOLLAR
  SIZE HAIL.  THIS STORM WAS LOCATED NEAR WEBB...OR 14 MILES
  SOUTHEAST OF SPENCER...AND MOVING NORTHEAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL AFFECT MAINLY RURAL AREAS OF
  SOUTHEASTERN CLAY COUNTY.

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 4291 9497 4291 9507 4304 9515 4317 9492
      4317 9491 4312 9490 4294 9491
TIME...MOT...LOC 0828Z 228DEG 29KT 4298 9500
WIND...HAIL <58MPH 1.25IN

$$

CJ

1 follow-up statement

331 
WWUS53 KFSD 060847
SVSFSD

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

IAC041-060858-
/O.CAN.KFSD.SV.W.0102.000000T0000Z-120506T0900Z/
CLAY IA-
347 AM CDT SUN MAY 6 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN CLAY COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.

LAT...LON 4291 9497 4291 9507 4304 9515 4317 9492
      4317 9491 4312 9490 4294 9491
TIME...MOT...LOC 0848Z 228DEG 29KT 4309 9484

$$

CJ

The office that day

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

Issued	Product	Office	Counties	Lasted
May 6, 1:55 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	35 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.