Alert archive / South Dakota / Flash Flood Warnings in 2001

Flash Flood Warning 5, NWS Rapid City, SD

August 12, 2001Custer County, Pennington County, South Dakota; Weston County, Wyoming

NWS Rapid City, SD issued this flash flood warning at Aug 12, 2001, 5:21 PM MDT for Custer County, Pennington County, South Dakota; Weston County, Wyoming. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 12, 2001, 5:21 PM MDT (23:21 UTC)
Expired: Aug 12, 2001, 8:15 PM MDT
In force: 3 hr
Issued by: NWS Rapid City, SD
Area: Whole counties; the outline is the Mesonet’s reconstruction

Counties Custer County, SD, Pennington County, SD, Weston County, WY

The radar

The Rapid City radar (KUDX), 70 km from the middle of the area, began a volume at 23:24 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.

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.4 hours before the alert went out and 390 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: 758 J/kg
Mixed-layer CIN: -199 J/kg
Mixed-layer LCL: 1445 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 97 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 flash flood 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 flash flood warning went out at Aug 12, 3:15 PM MDT, 2 hours 6 minutes earlier.

Area forecast discussion, Aug 12, 3:15 PM MDT, 2 hours 6 minutes before

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
315 PM MDT MON AUG 12 2001

VIGOROUS UPR TROF WORKING EAST OUT OF THE GT BASIN INTO CNTRL
ROCKIES...WITH MODEST MID-UPR LVL MOISTURE AS SEEN IN H20 VAPOR.
SHORT WAVE RIDGING AND NVA ACRS WRN SD AHEAD OF TROF KEEPING CAP IN
PLACE...EXCEPT OVER HILLS WHERE AFTN HEATING HAS REACHED LFC. CAP
HAS ALL BUT ERODED ACRS ERN WY. CONVECTION CURRENTLY OVER BIG HORNS
SHOULD HOLD TOGETHER AS IT MOVES EWD INTO NERN WY ALONG LEADING EDGE
OF SHORT WAVE. THIS ACTIVITY HAS DECENT CHANCE OF WORKING ACRS WRN
SD TONIGHT...WHERE DEW POINTS ARE SLOWLY CREEPING UPWARDS TOWARD
60F. 35-40KT LLJ FORMS TONIGHT OVR SRN CWFA...WITH GOOD WAA AND
THETA-E ADVECTION TO AID IN CONTINUING CONVECTION. MAIN CONCERN
WITH ANY CONVECTION THIS AFTN/TNGT IS THE RISK OF HEAVY RAINS WITH
STM MTN GENERALLY LESS THAN 10KTS. GOOD CHANCE FOR PCPN CONTINUING
THROUGH TOMORROW AS UPR/SFC TROF WORKS ACRS AREA. COLD PUSH DOES NOT
ACTUALLY MAKE IT THROUGH UNTIL TOMORROW EVE. PRES RISES OF 2-3MB
WILL MAKE FOR A WINDY NIGHT TUE NIGHT ACROSS MUCH OF CWFA. CAA IN
FULL SWING WED...BUT MID LVL INSTABILITY ALONG WITH SHORT WAVE
EMBEDDED IN NW FLOW ALOFT WILL KEEP THREAT OF PCPN FOR WED.

EXTENDED...STRONGEST NW FLOW ALOFT LOOKS TO REMAIN EAST OF CWFA
THROUGH SAT...FOR MOSTLY DRY AND PLEASANT CONDITIONS. NEXT TROF
MOVING INTO PAC NW BY SUN WILL AMPLIFY RIDGE A BIT ACRS CWFA FOR
WARM-UP.  BUT RETURNING SW FLOW ALOFT WILL ALSO LEAD TO BETTER
THREAT FOR CONVECTION.

UNR...NONE.
JOHNSON

In the hours before

Local storm report, Aug 12, 4:06 PM MDT, 1 hour 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
406 PM MDT SUN AUG 12 2001

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

0325 PM    6 SE SILVER CITY          SD   .75 INCH HAIL
08/12/01   PENNINGTON                     REPORTED BY OFF-DUTY
                                          NWS EMPLOYEE.
                                          SHORT-LIVED LEFT-MOVING
                                          SUPERCELL.

Bunkers

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 12, 4:16 PM MDT	Severe Thunderstorm Warning	UNR	Pennington	44 min
Aug 12, 5:08 PM MDT	Severe Thunderstorm Warning	UNR	Custer	67 min

Nearby

Flash Flood Warnings in South Dakota, 2001 Flash Flood Warnings in Wyoming, 2001 Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.