Alert archive / Iowa / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 298, NWS Sioux Falls, SD

August 2, 2001Plymouth County, Sioux County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 2, 2001, 8:33 AM CDT for Plymouth County, Sioux County, Iowa. It was in force for 27 min. 1 report came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: Aug 2, 2001, 8:33 AM CDT (13:33 UTC)
Expired: Aug 2, 2001, 9:00 AM CDT
In force: 27 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties; the outline is the Mesonet’s reconstruction

Counties Plymouth County, IA, Sioux County, IA

The radar

The Sioux Falls radar (KFSD), 97 km from the middle of the area, began a volume at 13:35 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 2, 8:41 AM CDT	Thunderstorm Wind 52 E	Le Mars, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 1.6 hours before the alert went out and 173 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: 994 J/kg
Mixed-layer CIN: -290 J/kg
Mixed-layer LCL: 1330 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 89 m²/s²
0-3 km storm-relative helicity: 35 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS53 KFSD 021333
SVRFSD

IAC149-167-021400-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
833 AM CDT THU AUG 2 2001

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

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

* UNTIL 900 AM CDT

* AT 833 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS FROM 6 MILES NORTHWEST OF REMSEN TO 30
  MILES SOUTHEAST OF REMSEN...OR FROM 8 MILES NORTHEAST OF LE MARS TO
  13 MILES NORTH OF IDA GROVE...MOVING NORTHEAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL REMAIN IN...

  RURAL AREAS OF PLYMOUTH AND SIOUX COUNTIES

THIS STORM WILL PRODUCE DAMAGING WIND. GO INSIDE A STURDY BUILDING
AND STAY AWAY FROM WINDOWS.

LAT...LON 4276 9622 4272 9588 4303 9587 4303 9617

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 2, 3:30 AM CDT, 5 hours 3 minutes earlier.

Area forecast discussion, Aug 2, 3:30 AM CDT, 5 hours 3 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
330 AM CDT THU AUG 2 2001

SHWRS/TSTMS AFFECTING FAR SERN CWA NEAR STORM LAKE ATTM...AND ALSO
APPROACHING SWRN CWA FM NEB. OBVIOUSLY THE CHANCES OF SHWRS/TSTMS
WILL HAVE TO BE COVERED FOR IN SRN CWA FOR MOST OF TDA INTO TNGT
AS TROPICAL RIDGE RIDERS INTERACT WITH LINGERING LOW LVL BOUNDARY.
THERE IS EVEN A CHANCE OF DVLPMT FURTHER N IN CWA AS TROPICAL
MOISTURE INTERACTS WITH NRN STREAM AND WITH RETURN SELY FLW THRU
850MB BY LATE AFTN INTO TNGT. ONLY PLACE THAT COULD BE PROTECTED
IS SWRN MN AND ADJ NWRN IA THRU TNGT AS LOW LVL RDG HOLDS...BUT
THESE AREAS PROBABLY ALSO HAVE THE BEST CHCS FOR NGTTIME AND EARLY
MRNG FOG. HIGH TEMPS TDA AND MAYBE FRI MAY BE TEMPERED BY CLDS AND
HUMIDITY ESP IN SRN CWA. BEST CHC MIXING TO LWR TO MID 90S WL BE
NWRN CWA NR HON...MHE...AND CHB FRI...OTRW MID TO UPR 80S MAY BE
THE BRULE.

.FSD...NONE
RYRHOLM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 2, 7:29 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth	31 min
Aug 2, 7:45 AM CDT	Severe Thunderstorm Warning	FSD	Woodbury	30 min
Aug 2, 7:57 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth	33 min
Aug 2, 8:10 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Ida, Woodbury	35 min
Aug 2, 8:38 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee	37 min
Aug 2, 8:52 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, O'Brien	38 min
Aug 2, 9:28 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	17 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2001 Every severe thunderstorm warning in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.