Alert archive / South Dakota / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 275, NWS Sioux Falls, SD

July 20, 2001Beadle County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 20, 2001, 7:55 AM CDT for Beadle County, South Dakota. It was in force for 35 min. 2 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jul 20, 2001, 7:55 AM CDT (12:55 UTC)
Expired: Jul 20, 2001, 8:30 AM CDT
In force: 35 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Beadle County, SD

The radar

The Aberdeen radar (KABR), 116 km from the middle of the area, began a volume at 12:54 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
Jul 20, 8:25 AM CDT	Hail 1.75	Wolsey, SD
Jul 20, 8:25 AM CDT	Hail 0.75	Wolsey, SD

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

Aberdeen, SD (KABR), launched 12:00Z, 0.9 hours before the alert went out and 55 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: 2369 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 779 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 121 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 8.3

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Jul 20, 3:40 AM CDT, 4 hours 15 minutes earlier.

Area forecast discussion, Jul 20, 3:40 AM CDT, 4 hours 15 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
340 AM CDT FRI JUL 20 2001

PRIND CURNT ACTVTY MOVG OVER WW AREA WILL GET CLOSE TO NERN CRNR OF
FCST AREA MAINLY IN SWRN MN...AND WILL INCLUDE SCT TSTMS THIS MRNG
FOR THAT AREA. OTRW LOOKS TOO CAPPED FOR ACTVTY TDA. INDICATIONS BY
ALL MODELS OF SOME MID LVL CONVECTN ERY THIS MRNG DIDNT LOOK TOO
RIGHT W/O DECNT BOUNDRY AND SO FAR NO INDICATNS...SO WILL LEAVE OUT.
SAPPARNT MID LV CONVCTN EVEN SCENARIO REMINISCENT OF PAST FEW NIGHTS
FRTHR CONVECTN PSBL TNGT MAINLY NRN/NERN PART OF AREA AGN...BUT NOT
SURE ENUF TO TAKE OUT THAT LTL 20 PCT MENTN FRTHR S. SUN WILL BE
INTRSTG...WITH AMS PRETTY WELL CAPPED...BUT WITH CDFNT COMNG INTO
FCST AREA LIFT MAY BE ENUF TO TAP HUMID AIR AND INSTBLTY. CERTAINLY
SUN NGT DESERVES MENTN. LTL CHANGE IN EXTNDED...LOOKS PRETTY GOOD IN
GNRL...LOOKG AT AVN/MRF MAKES ME THINK WE ARE OVERDOING TSTM CHC BUT
FNTL BOUNDRY MAY BE STUBBORN ABOUT GETTNG VERY FAR S. MODELS HAVE
OVERDONE THAT MORE THAN ONCE THIS SUMMER. WILL MENTN AREA OF FOG IN
FCST FOR THIS MRNG. GUIDNCE TEMPS N GNRLY LOOK PRETTY GOOD.

.FSD...NONE
WILLIAMS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 7:45 AM CDT	Severe Thunderstorm Warning	FSD	Brookings, Kingsbury	30 min
Jul 20, 8:33 AM CDT	Severe Thunderstorm Warning	FSD	Beadle	27 min
Jul 20, 12:30 PM CDT	Tornado Warning	FSD	Jackson	30 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 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.