Hail in South Dakota, August 7, 2020

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
248 PM MDT Fri Aug 7 2020

.DISCUSSION...(This Evening Through Friday)
Issued at 246 PM MDT Fri Aug 7 2020

Water vapor imagery shows an upper low cross Canada just north of
Montana, with W/SW flow across the CWA. Several embedded waves are
pushing through WY into western SD. Surface analysis shows a trough
across near KIEN, with deep southerly flow across south central SD.
Temps are in the upper 80s to low 90s across Tripp County, with
dewpoints in the low 70s. Behind the trough, dewpoints were 10-15
degrees lower, with temps in the 90s. KUDX radar shows isolated
storms having developed from the southern Black Hills into northeast
WY. Storms will continue to develop over the next several hours and
move eastward. Strong instability is in place, but shear remains
relatively weak, so a few storms could be strong or severe. CAMs
show storms affecting the Black Hills area early this evening ahead
of a cold front moving in from the NW, then another post-
frontal cluster associated with the next upper wave will push
through northeast WY in the mid evening hours, then push to the
Black Hills late this evening into the overnight hours. Lingering
storms will be possible early Saturday morning across central SD,
near the frontal boundary. The front is expected to drift through
south central SD on Saturday. Very strong instability will couple
with good shear ahead of the front, with severe storms possible
across south central SD. It is still possible the the bulk of
convection will develop east of the CWA, depending on the
timing of convection and position of the front. Can't rule out a few
diurnal based storms on Sunday, but generally drier weather is
expected, with breezy NW winds and cooler temperatures to the
northwest. Drier pattern will continue into early next week, with
highs in the 80s, then a warming trend is expected toward midweek.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1119 AM MDT Fri Aug 7 2020

VFR conditions are expected through most of the period. Isolated
thunderstorms are possible again this afternoon and evening,
especially around the Black Hills. Gusty winds will be possible
INVOF any TS.

&&

.FIRE WEATHER...
Issued at 246 PM MDT Fri Aug 7 2020

RHs at 15% or below are expected across portions of northeast WY
Saturday afternoon. However, winds are expected to be generally
light. This will result in elevated fire weather concerns.

&&

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

DISCUSSION...13
AVIATION...15
FIRE WEATHER...13

Hazardous Weather Outlook
National Weather Service Rapid City SD
435 AM MDT Fri Aug 7 2020

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-081300-
Harding-Perkins-Butte-Northern Meade Co Plains-Ziebach-
Northern Black Hills-Northern Foot Hills-Rapid City-
Southern Foot Hills-Central Black 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-Northern Campbell-Southern Campbell-
Western Crook-Wyoming Black Hills-Weston-Northeastern Crook-
435 AM MDT Fri Aug 7 2020 /535 AM CDT Fri Aug 7 2020/

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

.DAY ONE...Today and Tonight

Scattered to isolated thunderstorms are expected this afternoon
and evening. Isolated strong to severe storms will be possible,
particularly around the Black Hills area.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Thunderstorms will be possible at times in the period. Isolated
severe weather will be possible at times.

.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

Special Weather Statement
National Weather Service Rapid City SD
241 PM MDT Fri Aug 7 2020

WYZ054-056-072130-
Northern Campbell WY-Western Crook WY-
241 PM MDT Fri Aug 7 2020

...STRONG THUNDERSTORM OVER EAST CENTRAL CAMPBELL AND SOUTHWESTERN
CROOK COUNTIES...

At 240 PM MDT, Doppler radar was tracking a strong thunderstorm over
Rozet, or 12 miles east of Gillette, moving east at 25 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Moorcroft, Rozet and western Keyhole Reservoir.

This includes Interstate 90 in Wyoming between Mile Markers 138 and
159.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4422 10528 4431 10529 4446 10485 4425 10484
TIME...MOT...LOC 2040Z 250DEG 24KT 4427 10523

Rudge

Special Weather Statement
National Weather Service Rapid City SD
416 PM MDT Fri Aug 7 2020

SDZ024-028-072245-
Northern Black Hills SD-Central Black Hills SD-
416 PM MDT Fri Aug 7 2020

...STRONG THUNDERSTORM OVER SOUTHEASTERN LAWRENCE AND WEST CENTRAL
PENNINGTON COUNTIES...

At 416 PM MDT, Doppler radar was tracking a strong thunderstorm 3
miles west of Roubaix Lake, or 10 miles south of Lead, moving east at
20 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Rochford, Mystic, and Roubaix Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4415 10384 4428 10379 4423 10350 4405 10361
TIME...MOT...LOC 2216Z 288DEG 16KT 4420 10373

Eagan