Damaging Winds in Wyoming, August 6, 2020

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
246 PM MDT Thu Aug 6 2020

.DISCUSSION...(This Evening Through Thursday)
Issued at 245 PM MDT Thu Aug 6 2020

Upper ridging has moved across the central CONUS, with a trough now
pushing onshore the Pac NW coast. An upper wave is pushing across
the northern Rockies into central WY and the central Rockies. Deep
southerly low level flow has persisted across the region, ahead of
broad low pressure across Montana to Wyoming. Temperatures have
risen into the 80s to low 90s. Dewpoints are in the 70s across south
central SD, and 50s to 60 over western SD to northeast WY. Surface
analysis shows a dryline just southwest of Campbell County, WY,
where dewpoints are in the 30s on the other side of the boundary.
This dryline is expected to push across northeast WY late this
afternoon and into western SD in the evening/overnight hours. Strong
instability extends across the CWA, but shear is marginal. Storms
will push across northeast WY into far western SD late this
afternoon into the evening hours, along and ahead of the dryline. A
few storms may become severe, but lack of strong shear will limit
organization. Some lingering storms are expected in the overnight
hours; otherwise, quiet weather is expected through Friday morning.
Warmer temperatures are expected, with highs in the upper 80s to
around 100. A cold front is progged to push across the CWA Friday
night as embedded waves within southwest flow aloft push across the
CWA. This will bring isolated storms, mainly across northwest SD.
Instability will be strong, but shear will be weak. The best forcing
will be east of the CWA across the eastern Dakotas. Active southwest
flow aloft will continue into Saturday, with several waves crossing
the region. Friday night's cold front will become stationary across
south central SD. Low pressure is expected to develop along the
front. Strong instability and good shear on the warm side of the
front will allow for strong to severe storms to develop in the
afternoon and evening. The big question for the CWA will be the
position of this frontal boundary as peak heating develops. Storm
development may be over south central SD, but may quickly push east
of the CWA by evening. Generally dry weather is expected through
early next week. Highs will generally be near average.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1119 AM MDT Thu Aug 6 2020

VFR conditions are expected through most of the period. Isolated
to scattered thunderstorms will bring some MVFR/IFR conditions to
northeastern WY late this afternoon and to western SD this
evening.

&&

.FIRE WEATHER...
Issued at 245 PM MDT Thu Aug 6 2020

Near-critical fire weather conditions continue to look possible on
Friday across portions of northeastern WY and southwestern SD.
Limiting factor will be winds. Breezy conditions are expected on
Sunday with near-critical relative humidity values.

&&

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

DISCUSSION...13
AVIATION...Bunkers
FIRE WEATHER...13

Hazardous Weather Outlook
National Weather Service Rapid City SD
426 AM MDT Thu Aug 6 2020

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-071300-
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-
426 AM MDT Thu Aug 6 2020 /526 AM CDT Thu Aug 6 2020/

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

.DAY ONE...Today and Tonight

Scattered thunderstorms are expected late this afternoon and
evening. Isolated strong to severe storms will be possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

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
415 PM MDT Thu Aug 6 2020

WYZ054-062245-
Northern Campbell WY-
415 PM MDT Thu Aug 6 2020

...STRONG THUNDERSTORM OVER NORTHWESTERN CAMPBELL COUNTY...

At 415 PM MDT, Doppler radar was tracking a strong thunderstorm 4
miles northwest of Spotted Horse, or 38 miles northwest of Gillette,
moving northeast at 30 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Spotted Horse and Recluse.

LAT...LON 4499 10603 4500 10591 4500 10576 4466 10550
      4450 10601
TIME...MOT...LOC 2215Z 231DEG 27KT 4474 10592

Eagan

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
437 PM MDT THU AUG 06 2020

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

0430 PM     HAIL             5 W SPOTTED HORSE       44.72N 105.94W
08/06/2020  E0.25 INCH       CAMPBELL           WY   TRAINED SPOTTER

            WINDS ESTIMATED AT 50 MPH. 0.37 INCHES OF RAIN IN 15
            MINUTES.

&&

EVENT NUMBER UNR2002681

MLS