Alert archive / South Dakota / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 140, NWS Rapid City, SD

August 21, 2002Bennett County, South Dakota

NWS Rapid City, SD issued this severe thunderstorm warning at Aug 21, 2002, 11:31 PM MDT for Bennett County, South Dakota. It was in force for 59 min. 1 report 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: Aug 21, 2002, 11:31 PM MDT (05:31 UTC)
Expired: Aug 22, 2002, 12:30 AM MDT
In force: 59 min
Issued by: NWS Rapid City, SD
Area: Counties, with a storm outline in the text

County Bennett County, SD

What was reported inside it

Time	Report	Where	Remark
Aug 22, 12:01 AM MDT	Thunderstorm Wind 57 E	Allen, 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 5.5 hours before the alert went out and 246 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: 508 J/kg
Mixed-layer CIN: -78 J/kg
Mixed-layer LCL: 2396 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -29 m²/s²
0-3 km storm-relative helicity: 70 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.4

Open this sounding in Storm Lab

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 Rapid City, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 3:23 PM MDT, 8 hours 8 minutes earlier.

Area forecast discussion, Aug 21, 3:23 PM MDT, 8 hours 8 minutes before

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
230 PM MDT WED AUG 21 2002

MDLS IN FAIR AGREEMENT WITH SYNOPTIC FEATURES BUT DIFFER A BIT ON
PLACEMENT AND TIMING OF DISTURBANCES. A FEW STORMS DVLPG OVR THE BLK
HILLS AND NE WY ATTM AND EXPECT THAT MORE STORMS WL CONTINUE DVLPG
TO THE N AND E OF THIS AREA THROUGH THE REMAINDER OF THE AFTN AND
INTO THE EVE AS S/W LIFTS OUT OF ERN WY. LO CLDS HAVE REMAINED IN
PLACE ACRS NRN HALF OF CWA THIS AFTN...AND NO REASON THEY WL GO AWAY
TNGT. THINKING IS THAT AS WINDS BECOME MORE E-NE OVR AREA...THIS WL
HELP MORE LO CLDS TO DVLP OVR MUCH OF THE CWA. SINCE THIS MOISTURE
IS PRETTY SHALLOW...MOST OF THE HILLS SHLD STAY PTLY CLDY. LOWS SHLD
ONCE AGAIN BE ABV MOS GIVEN CURRENT DEW POINTS ACRS CWA AND WHAT WL
ADVECT IN FM THE E.

THU WINDS WL START TO SHIFT TO THE SE AS HI MOVES OVR GT LKS. GD
SETUP FOR STRONG SE WINDS BY AFTN ACRS WRN HALF OF CWA. BIGGEST
QUESTION IS HOW MUCH THE LO CLDS WL BREAK UP THROUGH THE DAY.  THINK
IT MAY BE TOUGH FOR FAR ERN COUNTIES TO GET OUT OF THE LO CLDS
BEFORE MID AFTN WHEN WINDS SHIFT AND HAVE KEPT TEMPS THERE ABOUT 5
DEG COOLER THAN THE W WHERE IT SHLD WARM INTO THE MID TO UPR 80S.
SOME WEAK RIDGING WL TAKE PLACE OVR AREA THROUGH THE DAY...BUT A
WEAK DISTURBANCE WL MOVE THRU THE S IN THE AFTN AND MAY TRIGGER A
FEW STORMS. ANOTHER S/W WL APPROACH NE WY LATE AND MAY SEE A FEW
STORMS THERE AS WELL. KEPT N DRY. THU NIGHT...S/W FM NE WY WL MOVE
ACRS WRN CWA AND HAVE KEPT 20 POPS GOING. OTHERWISE LOWS AGAIN IN
THE UPR 50S TO LWR 60S AS SE WINDS SHLD KEEP SOME LL MOISTURE AROUND.

FRI...A COUPLE OF DISTURBANCES WL MOVE ACRS CWA AND CONTINUE A CHC
FOR TSMS WITH DECENT MOISTURE AROUND. CAPES WL BE 1000-1500J/KG WITH
LTL OR NO CIN. INCLUDED 30 POPS EVERYWHERE. TEMPS SHLD REACH THE 80S
EVERYWHERE AS LO CLDS SHLD BE AT A MINIMUM. EXPECT MAINLY DRY CONDS
ACRS AREA FRI NIGHT AS GD NVA ACRS CWA. AVN SHOWING TROF ROTATING
THRU AREA SAT AND PUT IN A CHC FOR TSMS AGAIN ACRS CWA. TEMPS
SIMILAR TO FRI.

IN THE EXTENDED...SUN KEPT DRY WITH NO REAL DISTURBANCE MVG
THRU...BUT UPR TROF APPROACHES AREA BY MON WITH A CHC FOR TSMS THRU
WED ALONG WITH COOLER TEMPS...MAINLY IN THE MID TO UPR 70S BY TUE
AND WED.

.UNR...FLOOD WATCH UNTIL 930 PM MDT FOR LAWRENCE COUNTY-SDZ024.
JMG

In the hours before

Local storm report, Aug 21, 8:15 PM MDT, 3 hours 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
815 PM MDT WED AUG 21 2002

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

0350 PM    6S WOOD                   SD   1 INCH HAIL
08/21/02   MELLETTE                       REPORTED BY PUBLIC.

0515 PM    18NW WITTEN               SD   .88 INCH HAIL
08/21/02   TRIPP                          REPORTED BY PUBLIC.

0525 PM    1S WINNER                 SD   1 INCH HAIL
08/21/02   TRIPP                          REPORTED BY SPOTTER.

0650 PM    10NE ZEONA                SD   1.75 INCH HAIL
08/21/02   PERKINS                        REPORTED BY PUBLIC.
                                          FELL FOR 15 MINUTES

WFO UNR STAFF

The office that day

Everything else NWS Rapid City, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 21, 6:47 PM MDT	Severe Thunderstorm Warning	UNR	Perkins	43 min
Aug 21, 7:14 PM MDT	Severe Thunderstorm Warning	UNR	Fall River	46 min
Aug 21, 10:02 PM MDT	Severe Thunderstorm Warning	UNR		58 min
Aug 21, 11:02 PM MDT	Severe Thunderstorm Warning	UNR		43 min
Aug 22, 1:04 AM MDT	Severe Thunderstorm Warning	UNR	Todd	56 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 2002 Every severe thunderstorm warning in 2002

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.