Alert archive / South Dakota / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 141, NWS Rapid City, SD

July 22, 2021Butte County, Meade County, Perkins County, South Dakota

NWS Rapid City, SD issued this severe thunderstorm warning at Jul 22, 2021, 4:48 PM MDT for Butte County, Meade County, Perkins County, South Dakota. It was in force for 57 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
Jul 22, 2021, 4:48 PM MDT (22:48 UTC)
Expired
Jul 22, 2021, 5:45 PM MDT
In force
57 min
Issued by
NWS Rapid City, SD
Area
Storm-based polygon
Hail
0.75 in
Wind
70.0 mph

Counties Butte County, SD, Meade County, SD, Perkins County, SD

The radar

The Rapid City radar (KUDX), 96 km from the middle of the area, began a volume at 22:51 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

Rapid City, SD (KUNR), launched 12:00Z, 10.8 hours before the alert went out and 102 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-pSkew-T log-p diagram, Rapid City, SD at 12:00Z on 2021-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 578 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Rapid City, SD at 12:00Z on 2021-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
578 J/kg
Mixed-layer CIN
-149 J/kg
Mixed-layer LCL
2111 m above ground
0-6 km bulk shear
12 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
50 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Jul 22, 1:10 PM MDT, 3 hours 38 minutes earlier.

Area forecast discussion, Jul 22, 1:10 PM MDT, 3 hours 38 minutes before
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
110 PM MDT Thu Jul 22 2021

.DISCUSSION...(This Evening Through Thursday)
Issued at 107 PM MDT Thu Jul 22 2021

The large-scale ridge will dominate our weather pattern for the
next week, with amplification of the ridge next week leading to
near-record/record high temperatures. For today and tonight, a
short-wave trough will top the ridge bringing scattered showers
and thunderstorms to much of the area, but especially the BLKHLS
and northwestern part of the CWA where CAPE and shear will be
sufficient for a few severe thunderstorms. Inverted-V soundings
and midlevel moisture will be favorable for severe wind gusts,
which will be the primary severe hazard, consistent with the SPC
and HREF guidance. PWATs of 175-200 percent of average along with
light mean winds will favor locally heavy rainfall as well. An
LLJ should keep the MCS going eastward across the CWA overnight.

The short-wave trough will push a weak boundary southeast across the
CWA late tonight and Friday, reaching south-central SD by late
afternoon. Another short-wave trough will flatten the ridge as it
moves across the northern CONUS on Friday. Shear with this wave
will be even stronger given proximity of a 70-kt plus upper jet,
which when combined with the CAPE and moisture should be even more
favorable for some severe thunderstorms (compared to today). The
main concern is over the BLKHLS and places eastward close to the
surface boundary. Saturday and Sunday should be less active, but
some warm advection/LLJ and Q-vector convergence (especially
Saturday) may foster thunderstorms over the far southwestern CWA.

Model and ensemble agreement is high for a very hot period Monday
through Thursday of next week, with Tuesday and Wednesday looking
particularly hot. The NBM is showing near-record highs, which are
possible given the 850- and 700-mb temperatures, but also contingent
on the amount mid- and upper-level smoke. Otherwise, thunderstorm
chances will be at a minimum, until perhaps later Wednesday and
Thursday as the better monsoonal moisture returns to the CWA.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1136 AM MDT Thu Jul 22 2021

A surface boundary moving through the area could produce scattered
thunderstorms later this afternoon into early evening from
northeast WY into western SD. Some of the storms could be strong
with small hail and gusty winds. Local IFR/MVFR conditions could
be found with the thunderstorms as well. After 23/02z VFR conds
are expected through the remainder of the valid terminal forecast.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

DISCUSSION...Bunkers
AVIATION...Hintz
Hazardous weather outlook, Jul 22, 3:51 AM MDT, 12 hours 57 minutes before
Hazardous Weather Outlook
National Weather Service Rapid City SD
351 AM MDT Thu Jul 22 2021

SDZ002-013-014-026-027-029>032-041>044-046-047-049-072>074-WYZ055-
058-231300-
Perkins-Northern Meade Co Plains-Ziebach-Rapid City-
Southern Foot Hills-Southern Black Hills-Custer Co Plains-
Pennington Co Plains-Haakon-Fall River-Oglala Lakota-Jackson-
Bennett-Mellette-Todd-Tripp-Sturgis/Piedmont Foot Hills-
Southern Meade Co Plains-Hermosa Foot Hills-Southern Campbell-
Weston-
351 AM MDT Thu Jul 22 2021 /451 AM CDT Thu Jul 22 2021/

This Hazardous Weather Outlook is for portions of western South
Dakota and northeastern Wyoming.

.DAY ONE...Today and Tonight

There is a chance of thunderstorms this afternoon into tonight.
Severe thunderstorms are not expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is a chance of thunderstorms each day through the weekend.
There is a marginal risk of severe thunderstorms on Friday for
much of western South Dakota.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

SDZ001-012-024-025-028-WYZ054-056-057-071-231300-
Harding-Butte-Northern Black Hills-Northern Foot Hills-
Central Black Hills-Northern Campbell-Western Crook-
Wyoming Black Hills-Northeastern Crook-
351 AM MDT Thu Jul 22 2021

This Hazardous Weather Outlook is for portions of western South
Dakota and northeastern Wyoming.

.DAY ONE...Today and Tonight

There is a chance of thunderstorms this afternoon into tonight.
There is a marginal risk of severe thunderstorms with hail and
damaging winds.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is a chance of thunderstorms each day through the weekend.
There is a marginal risk of severe thunderstorms on Friday for
much of western South Dakota.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

In the hours before

Local storm report, Jul 22, 4:03 PM MDT, 45 minutes before
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Local storm report, Jul 22, 4:14 PM MDT, 34 minutes before
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Special weather statement, Jul 22, 4:29 PM MDT, 19 minutes before
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Local storm report, Jul 22, 4:37 PM MDT, 11 minutes before
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Local storm report, Jul 22, 4:45 PM MDT, 3 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
445 PM MDT THU JUL 22 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     TSTM WND GST     7 WSW HOOVER            45.07N 103.40W
07/22/2021  M54 MPH          BUTTE              SD   MESONET

&&

MLS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 22, 3:28 PM MDTSpecial Weather StatementUNRHarding62 min
Jul 22, 3:33 PM MDTSevere Thunderstorm WarningUNRButte, Harding57 min
Jul 22, 4:01 PM MDTSevere Thunderstorm WarningUNRButte, Harding, Perkins59 min
Jul 22, 4:29 PM MDTSpecial Weather StatementUNRButte, Lawrence61 min
Jul 22, 4:56 PM MDTSpecial Weather StatementUNRMeade64 min
Jul 22, 5:41 PM MDTSevere Thunderstorm WarningUNRMeade, Perkins, Ziebach79 min
Jul 22, 5:47 PM MDTSpecial Weather StatementUNRCuster, Pennington58 min
Jul 22, 2:57 PM MDTSpecial Weather StatementUNRCrook48 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 2021Every severe thunderstorm warning in 2021

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.