Damaging Wind in South Dakota, July 30, 2023

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
800 PM MDT Sun Jul 30 2023

.UPDATE...
Issued at 800 PM MDT Sun Jul 30 2023

Scattered to numerous showers and thunderstorms continue across
much of northeast WY and western SD early this evening as
upper level disturbance moves through the ridge and across our
area. The strongest storms over the last few hours have been
across portions of northeast WY, where golf ball size or larger
hail and wind gusts to over 70 mph have been reported with the
strongest storms, with a line of severe storms now over central
to southern Weston County. Some of this activity will at least
push into far southwest SD over the next hour or two, with
additional stronger storms likely developing further to the east
across the severe thunderstorm watch area as well. MUCAPE values
of 1500 to over 3000 j/kg are still in place over far northeast WY
and southwest SD as storms are likely to become or will be
elevated over time. Shear will weaken a bit as well but still
plenty strong in the near term for organized storms. Activity
should start to weaken in intensity with time late this evening
and especially overnight as the disturbance moves east and storms
gradually exit from west to east. Minor adjustments have been made
to the forecast for the next few hours. Northern portions of the
watch will likely be removed soon and will monitor whether parts
of the watch may need to be extended a bit beyond 04z.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 303 PM MDT Sun Jul 30 2023

Current surface analysis shows frontal boundary just to the west
and southwest of the forecast area, with southeasterly low level
winds continuing to bring increasing moisture over much of the
forecast area. A couple of weaker surface boundaries are noted
across the Black Hills area as well. Dewpoints range from the 50s
over northeast WY and the higher Black Hills to 60s to around 70
degrees elsewhere. Upper level analysis shows ridge axis over WY
and central MT, with weak disturbances passing through the ridge.
One disturbance is located over western into central SD, with a
stronger one moving across south central MT/northern WY. Regional
radars are showing isolated/scattered storms now over WY into far
western SD. A severe storm has pushed through portions of the
northern/central Black Hills this afternoon. Temps are in the 80s
to lower 90s, cooler where rain has fallen, with muggy conditions
across the SD plains.

Isolated/widely scattered storms, possibly strong to severe, will
continue to affect the Black Hills area and parts of northwest/west
central SD into the late afternoon, as the first disturbance slides
through western SD. MLCAPE of 1500 to over 3000 j/kg has developed
this afternoon over much of the area. Shear remains quite favorable
for supercells and organized multicells through the evening. Large
hail, possibly very large hail, and strong wind gusts will be the
main threats from any severe storms. The second disturbance further
west is expected to bring more widespread showers and storms from
west to east late today and into tonight. Large hail and strong wind
gusts will be the main threats as well, but wind could become the
bigger threat as the evening goes on, as storms could organize into
one or two lines during the evening. With precipitable water values
well above average, at least locally heavy rain can be expected,
though movement of storms should be relatively fast with that round
of storms. However, will have to watch for any training of storms
this afternoon into tonight for potential localized flooding.

Storms could linger much of the night and possibly into Monday
morning over eastern portions of the forecast area, especially
toward central SD, though the threat for severe storms will drop off
into the overnight hours. Warm and relatively humid conditions will
persist for the first half of the week, with highs mostly in the 80s
and lower 90s and dewpoints remaining in the upper 50s to near 70.
Chances for storms should lessen some, along with the threat for
severe storms, as available CAPE gradually drops off and shear
weakens considerably by Tuesday. However, weak ridge rider
disturbances could bring isolated to scattered storms at times into
midweek. The risk for severe storms could increase toward the
Thursday/Friday period as ridge eventually shifts east of the region
and a more southwesterly flow regime aloft sets up from the Rockies
into the Plains. Chances for showers and storms will likely persist
through the extended period, with active flow and monsoonal moisture
across the Rockies into the high Plains. This could lead to a
relatively wet pattern. Temps will also drop off to below average
levels late week and especially over the weekend.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 525 PM MDT Sun Jul 30 2023

Scattered to numerous showers and thunderstorms will track from
west-northwest to east-southeast across much of the area through
the evening and into the overnight hours. Some storms could be
severe with large hail and strong wind gusts. Will keep tempo
groups in the TAF's this evening, with the better chances for
stronger storms at KRAP. MVFR conditions are likely in and near
stronger storms. Most of the activity will move east of the area
by early Monday morning, with patchy MVFR/IFR conditions possible
early in the day. Another chance for showers and thunderstorms is
then expected Monday afternoon across much of northeast WY and
western SD.

&&

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

Update...26
DISCUSSION...26
AVIATION...26

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Preliminary Local Storm Report
National Weather Service Rapid City SD
810 PM MDT Sun Jul 30 2023

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

0755 PM     Tstm Wnd Gst     6 WNW Newcastle         43.88N 104.32W
07/30/2023  M51 mph          Weston             WY   AWOS

&&

UNR

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Special Weather Statement
National Weather Service Rapid City SD
823 PM MDT Sun Jul 30 2023

SDZ041-042-310300-
Fall River SD-Oglala Lakota SD-
823 PM MDT Sun Jul 30 2023

...A strong thunderstorm will impact portions of west central Oglala
Lakota and northeastern Fall River Counties through 900 PM MDT...

At 823 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Smithwick, or 19 miles east of Hot Springs, moving
south at 20 mph.

HAZARD...Nickel size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible.

Locations impacted include...
  Hay Canyon Butte.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 1000 PM MDT for
southwestern South Dakota.

&&

LAT...LON 4340 10321 4344 10302 4329 10291 4321 10318
TIME...MOT...LOC 0223Z 339DEG 16KT 4337 10310

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...<30 MPH

JC

Preliminary Local Storm Report
National Weather Service Rapid City SD
840 PM MDT Sun Jul 30 2023

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

0828 PM     Hail             5 NNW Kyle              43.49N 102.22W
07/30/2023  E0.70 inch       Oglala Lakota      SD   Trained Spotter

&&

WFO UNR

Special Weather Statement
National Weather Service Rapid City SD
844 PM MDT Sun Jul 30 2023

SDZ030-042-310315-
Custer Co Plains SD-Oglala Lakota SD-
844 PM MDT Sun Jul 30 2023

...A strong thunderstorm will impact portions of southeastern Custer
and northwestern Oglala Lakota Counties through 915 PM MDT...

At 844 PM MDT, Doppler radar was tracking a strong thunderstorm 6
miles southwest of Red Shirt, or 26 miles northeast of Hot Springs,
moving east at 5 mph.

HAZARD...Nickel size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible.

Locations impacted include...
  Red Shirt Table Overlook.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Severe Thunderstorm Watch remains in effect until 1000 PM MDT for
southwestern South Dakota.

&&

LAT...LON 4359 10317 4362 10315 4364 10314 4369 10293
      4352 10285 4351 10316
TIME...MOT...LOC 0244Z 258DEG 5KT 4362 10302

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...<30 MPH

JC