Alert archive / South Dakota / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 20, NWS Sioux Falls, SD

May 10, 1999Aurora County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 10, 1999, 3:27 AM CDT for Aurora County, South Dakota. It was in force for 33 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 10, 1999, 3:27 AM CDT (08:27 UTC)
Expired: May 10, 1999, 4:00 AM CDT
In force: 33 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties

County Aurora County, SD

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 9, 10:00 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 8.5 hours before the alert went out and 132 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1346 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 164 m²/s²
0-3 km storm-relative helicity: 364 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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 May 10, 3:25 AM CDT, 2 minutes earlier.

Area forecast discussion, May 10, 3:25 AM CDT, 2 minutes before

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In the hours before

Special weather statement, May 9, 10:08 PM CDT, 5 hours 19 minutes before

SDZ050-057-058-063-064-100330-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1008 PM CDT SUN MAY 9 1999

...TORNADO WATCH NUMBER 232 EXPIRES...BUT HAS BEEN REPLACED BY SEVERE
THUNDERSTORM WATCH UNTIL 4AM CDT...

AS OF 10PM CDT...THE TORNADO WATCH WHICH HAS BEEN IN EFFECT THIS
EVENING ACROSS SOUTH CENTRAL SOUTH DAKOTA HAS BEEN ALLOWED TO EXPIRE.
HOWEVER...ORGANIZED THUNDERSTORMS ARE EXPECTED TO CONTINUE FOR MUCH
OF THE NIGHT...AND A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED UNTIL
4 AM FOR MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA.

THE PRIMARY THREAT FOR THE REMAINDER OF TONIGHT WILL BE LARGE
HAIL...HEAVY RAINS...AND DAMAGING WIND...BUT REMEMBER THAT SEVERE
THUNDERSTORMS CAN AN OCCASIONALLY DO PRODUCE TORNADOES WITH LITTLE OR
NO ADVANCE WARNING.

CHAPMAN

Special weather statement, May 9, 10:08 PM CDT, 5 hours 19 minutes before

SDZ050-057-058-063-064-100330-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1008 PM CDT SUN MAY 9 1999

...TORNADO WATCH NUMBER 232 EXPIRES...BUT HAS BEEN REPLACED BY SEVERE
THUNDERSTORM WATCH UNTIL 4AM CDT...

AS OF 10PM CDT...THE TORNADO WATCH WHICH HAS BEEN IN EFFECT THIS
EVENING ACROSS SOUTH CENTRAL SOUTH DAKOTA HAS BEEN ALLOWED TO EXPIRE.
HOWEVER...ORGANIZED THUNDERSTORMS ARE EXPECTED TO CONTINUE FOR MUCH
OF THE NIGHT...AND A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED UNTIL
4 AM FOR MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA.

THE PRIMARY THREAT FOR THE REMAINDER OF TONIGHT WILL BE LARGE
HAIL...HEAVY RAINS...AND DAMAGING WIND...BUT REMEMBER THAT SEVERE
THUNDERSTORMS CAN AN OCCASIONALLY DO PRODUCE TORNADOES WITH LITTLE OR
NO ADVANCE WARNING.

CHAPMAN

The office that day

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

Issued	Product	Office	Counties	Lasted
May 9, 10:42 PM CDT	Severe Thunderstorm Warning	FSD	Brule	33 min
May 10, 1:56 AM CDT	Severe Thunderstorm Warning	FSD	Gregory	34 min
May 10, 2:28 AM CDT	Severe Thunderstorm Warning	FSD	Charles Mix	37 min
May 10, 2:45 AM CDT	Severe Thunderstorm Warning	FSD	Gregory	35 min
May 10, 3:02 AM CDT	Severe Thunderstorm Warning	FSD	Charles Mix	18 min
May 10, 3:20 AM CDT	Severe Thunderstorm Warning	FSD	Brule, Charles Mix	35 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 1999 Every severe thunderstorm warning in 1999

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.