Alert archive / South Dakota / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 179, NWS Rapid City, SD

August 26, 2021Perkins County, South Dakota

NWS Rapid City, SD issued this severe thunderstorm warning at Aug 26, 2021, 2:18 AM MDT for Perkins County, South Dakota. It was in force for 42 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: Aug 26, 2021, 2:18 AM MDT (08:18 UTC)
Expired: Aug 26, 2021, 3:00 AM MDT
In force: 42 min
Issued by: NWS Rapid City, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

County Perkins County, SD

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 26, 2:16 AM MDT, 2 minutes earlier.

Area forecast discussion, Aug 26, 2:16 AM MDT, 2 minutes before

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
216 AM MDT Thu Aug 26 2021

.DISCUSSION...(Today Through Wednesday)
Issued at 213 AM MDT Thu Aug 26 2021

Broad upper ridging covers the eastern 2/3 of the CONUS, while an
upper trough is over the west coast. A cluster of strong to
severe thunderstorms continues to move along the ND/SD border.
With a surface low over central WY, southeasterly winds are breezy
across our CWA. Satellite shows some low to mid-level clouds
developing across central SD, as moisture flows in from the south.
Temperatures at 2 AM are in the 60s.

Overnight convection is expected to shift into eastern SD this
morning. Some low ceilings may linger across northwestern/central SD
through the day, and temperatures there are expected to be
noticeably cooler (70s) than areas farther south (80s). Surface low
will shift into northeastern WY today, with its associated warm
front draped along or near the SD/NE border, and dry line along the
SD/WY border. By this afternoon, over 2000 J/kg MLCAPE is expected
to develop across southwestern to south central SD. Shortwave energy
ahead of the approaching upper trough will contribute to
thunderstorm development; some of these storms could be severe,
considering the presence of 35-45 kts 0-6 km shear. These storms are
expected to track across the southern half of our CWA through the
evening. Overnight, another cluster of storms will be possible
across northwestern SD.

Mainly dry conditions are expected for Friday. Temperatures will
rebound as southerly winds become breezy ahead of the surface low. A
cool front will move through in the evening. As the main trough
crosses the region, most of its energy will be to our north.
However, some showers/storms will be possible Friday night across
northwestern SD.

Behind the front, Saturday will be cooler, with highs in the 70s to
lower 80s. A few showers/storms will be possible as the trough
continues to cross the region, but then zonal flow/weak upper
ridging will result in some drier weather. Starting Sunday, a
gradual warming trend is expected through early next week, with
temperatures returning to the 90s.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1043 PM MDT Wed Aug 25 2021

Scattered thunderstorms will move across the far northern and
northeastern part of the CWA overnight and early Thursday
morning, spreading widespread MVFR and some IFR CIGS southward
across much of northwestern and west-central SD. In addition,
moist southeast flow will result in some IFR CIG development
across parts of the rest of western SD. Models have been slow to
pick up on this, so suspect they are a bit underdone. The low
clouds may persist across parts of SD well into Thursday
afternoon, especially northeast of the CWA.

Otherwise, showers and thunderstorms are expected to develop over
northeastern WY on Thursday afternoon and spread eastward across
western SD through the early evening.

&&

.FIRE WEATHER...
Issued At 213 AM MDT Thu Aug 26 2021

Today will be warm and dry across northeastern WY, with relative
humidity dipping near 15%. Winds are not expected to be very
strong, though. On Friday, northeastern WY will be even drier,
with minimum RH of 10-15%. Southwesterly winds will be breezy
ahead of an approaching surface low, and then switch to the
northwest behind the low. Forecast soundings show the potential of
30-40 kt winds mixing down during the afternoon. With the gusty,
shifting winds and the dry conditions, decided to issue a Fire
Weather Watch.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...Fire Weather Watch from Friday afternoon through Friday evening
     for WYZ314>317.

&&

DISCUSSION...Pojorlie
AVIATION...Bunkers
FIRE WEATHER...Pojorlie

In the hours before

Special weather statement, Aug 26, 12:14 AM MDT, 2 hours 4 minutes before

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Special weather statement, Aug 26, 1:36 AM MDT, 42 minutes before

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Local storm report, Aug 26, 1:39 AM MDT, 39 minutes before

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Local storm report, Aug 26, 1:51 AM MDT, 27 minutes before

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Special weather statement, Aug 26, 2:06 AM MDT, 12 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 26, 12:14 AM MDT	Special Weather Statement	UNR	Harding	61 min
Aug 26, 12:35 AM MDT	Severe Thunderstorm Warning	UNR	Harding	55 min
Aug 26, 1:36 AM MDT	Special Weather Statement	UNR	Harding	39 min
Aug 26, 2:06 AM MDT	Special Weather Statement	UNR	Perkins	54 min
Aug 26, 2:12 AM MDT	Fire Weather Watch	UNR	Custer, Fall River	24 hr
Aug 26, 5:12 PM MDT	Special Weather Statement	UNR	Lawrence	33 min
Aug 26, 5:21 PM MDT	Severe Thunderstorm Warning	UNR	Lawrence, Meade, Pennington	54 min
Aug 26, 5:59 PM MDT	Severe Thunderstorm Warning	UNR	Pennington	61 min
Aug 26, 3:27 PM MDT	Severe Thunderstorm Warning	UNR	Campbell, Crook, Weston	63 min
Aug 26, 4:24 PM MDT	Special Weather Statement	UNR	Crook	36 min
Aug 26, 4:40 PM MDT	Severe Thunderstorm Warning	UNR	Crook	23 min
Aug 26, 5:13 PM MDT	Special Weather Statement	UNR	Weston	32 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 2021 Every 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.