Alert archive / Iowa / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 134, NWS Sioux Falls, SD

July 2, 1999Woodbury County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 2, 1999, 10:04 AM CDT for Woodbury County, Iowa. It was in force for 46 min. 4 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 2, 1999, 10:04 AM CDT (15:04 UTC)
Expired: Jul 2, 1999, 10:50 AM CDT
In force: 46 min
Issued by: NWS Sioux Falls, SD
Area: Whole counties

County Woodbury County, IA

The radar

The Omaha radar (KOAX), 122 km from the middle of the area, began a volume at 15:03 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
Jul 2, 10:05 AM CDT	Hail 0.75	Salix, IA
Jul 2, 10:10 AM CDT	Hail 2.75	Bronson, IA
Jul 2, 10:15 AM CDT	Thunderstorm Wind 70	Sloan, IA
Jul 2, 10:17 AM CDT	Thunderstorm Wind 57	Hornick, 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 2, 9:45 AM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 3.1 hours before the alert went out and 122 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: 217 J/kg
Mixed-layer CIN: -357 J/kg
Mixed-layer LCL: 1083 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 171 m²/s²
0-3 km storm-relative helicity: 406 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 Jul 2, 3:25 AM CDT, 6 hours 39 minutes earlier.

Area forecast discussion, Jul 2, 3:25 AM CDT, 6 hours 39 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
325 AM CDT FRI JUL 2 1999

SHWRS AND TSTMS WERE MOVG E OVR SE SD THIS MRNG WITH SFC LO TO SE
AND UPR LVL S/W. AREA WSR-88D SHWG STRONGEST TSTMS WERE MOVG SE THRU
S CNTRL SD AND HAV A HARD TIME RIGHT NOW PSHG E. TSTMS SHLD MOV E
WITH TIME THIS MRNG BUT LKS LIKE STGST STORMS WILL BE ALNG SRN PART
OF CWA. TSTMS DSPTG AFT SUNRISE AND WITH MSTR AND HEATG WILL KP A
SLGT OF LATE AFTN TSTMS GOING. GOING MORE ALNG WITH ETA/AVN FOR TNGT
AS JET SET UP AND TROF TO W. THINK MAIN THREAT OF TSTMS WILL BE A
LTL FURTHER N TNGT AS WRMFNT CONTS TO MOV N AND WAA INCRS OVR CWA.
MAY BE SOME LINGERING TSTMS E SAT MRNG. WENT MORE WITH FAN TEMPS FOR
TDA AND TNGT BUT THINK  A LTL COOLR FWC TEMPS LOOK BTR ON SAT WITH
AMOUNTS OF WATER THERE IS STANDING ARND.

.FSD...NONE

WB

In the hours before

Local storm report, Jul 2, 5:41 AM CDT, 4 hours 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
541 AM CDT FRI JUL 02 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0255 AM    BURKE                     SD    .88 INCH HAIL
07/02/99   GREGORY

0309 AM    2 SE BURKE                SD    .88 INCH HAIL
07/02/99   GREGORY                         HAIL DRIFTS TWO FEET
                                           DEEP ALONG HIGHWAY 18
                                           AS REPORTED BY COUNTY
                                           SHERIFF

0332 AM    BURKE                     SD    1.5 INCH HAIL
07/02/99   GREGORY                         QUARTER TO WALNUT
 SIZE
                                           HAIL

0359 AM    BONESTEEL                 SD    1 INCH HAIL
07/02/99   GREGORY

Local storm report, Jul 2, 5:41 AM CDT, 4 hours 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
541 AM CDT FRI JUL 02 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0255 AM    BURKE                     SD    .88 INCH HAIL
07/02/99   GREGORY

0309 AM    2 SE BURKE                SD    .88 INCH HAIL
07/02/99   GREGORY                         HAIL DRIFTS TWO FEET
                                           DEEP ALONG HIGHWAY 18
                                           AS REPORTED BY COUNTY
                                           SHERIFF

0332 AM    BURKE                     SD    1.5 INCH HAIL
07/02/99   GREGORY                         QUARTER TO WALNUT
 SIZE
                                           HAIL

0359 AM    BONESTEEL                 SD    1 INCH HAIL
07/02/99   GREGORY

Special weather statement, Jul 2, 7:00 AM CDT, 3 hours 4 minutes before

SDZ038-050-052>071-NEZ013-014-021230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  SIOUX FALLS SD
700 AM CDT FRI JUL 2 1999

...SEVERE THUNDERSTORM WATCH 507 HAS EXPIRED...

THE SEVERE THUNDERSTORM WATCH THAT WAS IN EFFECT FOR SOUTH CENTRAL
AND SOUTHEAST SOUTH DAKOTA AND NORTHEAST NEBRASKA HAS BEEN ALLOWED TO
EXPIRE AT 7 AM CDT. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE
OVER THE AREA UNTIL MID MORNING BUT FURTHER SEVERE WEATHER IS NOT
EXPECTED.

WB

WB

Special weather statement, Jul 2, 7:00 AM CDT, 3 hours 4 minutes before

SDZ038-050-052>071-NEZ013-014-021230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  SIOUX FALLS SD
700 AM CDT FRI JUL 2 1999

...SEVERE THUNDERSTORM WATCH 507 HAS EXPIRED...

THE SEVERE THUNDERSTORM WATCH THAT WAS IN EFFECT FOR SOUTH CENTRAL
AND SOUTHEAST SOUTH DAKOTA AND NORTHEAST NEBRASKA HAS BEEN ALLOWED TO
EXPIRE AT 7 AM CDT. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE
OVER THE AREA UNTIL MID MORNING BUT FURTHER SEVERE WEATHER IS NOT
EXPECTED.

WB

WB

Special weather statement, Jul 2, 8:10 AM CDT, 1 hour 54 minutes before

SDZ038>040-050-052>071-NEZ013-014-021615-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  SIOUX FALLS SD
810 AM CDT FRI JUL 2 1999

THE SEVERE STORM PREDICTION CENTER IN NORMAN OKLAHOMA...HAS PLACED
ALL OF SOUTH CENTRAL AND SOUTHEAST SOUTH DAKOTA ALONG WITH PART OF
NORTHEAST NEBRASKA IN A MODERATE RISK OF SEVERE WEATHER TODAY INTO
TONIGHT.

THUNDERSTORMS THAT WERE OVER THE AREA THIS MORNING ARE EXPECTED TO
DISSIPATE AS A WARM FRONT ACROSS CENTRAL NEBRASKA AND CENTRAL IOWA
MOVES NORTH. THUNDERSTORMS ARE THEN EXPECTED TO REDEVELOP AGAIN LATE
THIS AFTERNOON INTO TONIGHT TO THE NORTH OF THIS FRONT. SEVERE
WEATHER IS AGAIN POSSIBLE WITH LARGE HAIL AND DAMAGING WINDS.

YOU ARE ADVISED TO jLISTEN FOR LATER FORECAST AND WARNINGS CONCERNING
SEVERE WEATHER THAT MAY DEVELOP.

WB

WB

Special weather statement, Jul 2, 8:10 AM CDT, 1 hour 54 minutes before

SDZ038>040-050-052>071-NEZ013-014-021615-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  SIOUX FALLS SD
810 AM CDT FRI JUL 2 1999

THE SEVERE STORM PREDICTION CENTER IN NORMAN OKLAHOMA...HAS PLACED
ALL OF SOUTH CENTRAL AND SOUTHEAST SOUTH DAKOTA ALONG WITH PART OF
NORTHEAST NEBRASKA IN A MODERATE RISK OF SEVERE WEATHER TODAY INTO
TONIGHT.

THUNDERSTORMS THAT WERE OVER THE AREA THIS MORNING ARE EXPECTED TO
DISSIPATE AS A WARM FRONT ACROSS CENTRAL NEBRASKA AND CENTRAL IOWA
MOVES NORTH. THUNDERSTORMS ARE THEN EXPECTED TO REDEVELOP AGAIN LATE
THIS AFTERNOON INTO TONIGHT TO THE NORTH OF THIS FRONT. SEVERE
WEATHER IS AGAIN POSSIBLE WITH LARGE HAIL AND DAMAGING WINDS.

YOU ARE ADVISED TO jLISTEN FOR LATER FORECAST AND WARNINGS CONCERNING
SEVERE WEATHER THAT MAY DEVELOP.

WB

WB

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 2, 2:17 AM CDT	Severe Thunderstorm Warning	FSD	Gregory	48 min
Jul 2, 3:07 AM CDT	Severe Thunderstorm Warning	FSD	Charles Mix, Gregory	43 min
Jul 2, 3:52 AM CDT	Severe Thunderstorm Warning	FSD	Gregory	33 min
Jul 2, 4:20 AM CDT	Severe Thunderstorm Warning	FSD	Charles Mix	35 min
Jul 2, 7:45 AM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Union	35 min
Jul 2, 7:53 AM CDT	Tornado Warning	FSD	Union	32 min
Jul 2, 9:18 AM CDT	Severe Thunderstorm Warning	FSD	Union	47 min
Jul 2, 9:27 AM CDT	Flash Flood Warning	FSD	Union	2 hr
Jul 2, 11:32 AM CDT	Flash Flood Warning	FSD	Union	58 min
Jul 2, 8:07 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	33 min
Jul 2, 8:43 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, O'Brien, Plymouth, Sioux	47 min

Nearby

Severe Thunderstorm Warnings in Iowa, 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.