Severe Thunderstorm Warning 274, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
533 PM MDT Fri Aug 1 2025

.KEY MESSAGES...

- There is a Slight Risk (Level 2 of 5) for severe weather
  Friday afternoon and evening east of the Laramie Range. All
  modes of severe weather are possible: hail, winds, tornadoes,
  and flash flooding.

- There is a Marginal Risk of severe weather for Saturday,
  mainly across western Nebraska. Primary hazards look to be
  hail, wind, and flash flooding.

- Drier and warmer conditions return mid-week and continue
  through the weekend.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 118 PM MDT Fri Aug 1 2025

Another day of severe weather expected across the region but
ingredients are a step above yesterday's leading to a bit more
concentrated threat of severe weather across the region.
Current mesoanalysis is showing another moist environment with
PWAT values of 0.8-1.2 inches, while severe parameters include
MUCAPE maxing out at 3500 J/kg near the WY/CO/NE borders, bulk
shear values of 25-30 knots, and effective SRH of 100-150 m2/s2.
This is leading to an environment supportive of large hail,
strong winds, and perhaps even an isolated tornado or two. With
supercell composites of 2-4 from the Laramie Range and
eastwards, it seems all but certain we should see some stronger
thunderstorms into the mid to later part of the afternoon and
evening, and the expectation is that we should see a severe
thunderstorm watch within the next few hours with strong to
severe activity likely through the evening hours. With some of
these storms dropping rainfall rates of 1-2+ inches per hour, a
flooding risk cannot be ruled out as well.

Moving overnight activity should wane after the sun sets or move
out of the region, leading to a quiet evening. Tomrorow's setup
remains similar as it has been the past several days with the
best moisture axis continuing to pivot a bit more south and
eastwards. While we'll still remain in at least a marginal risk
for stronger to severe storms for our easternmost zones, the
best threat should be just south of the WY/NE border. And this
becomes apparent in our RH values as afternoon minimums descend
back below 50% for our eastern zones, while western zones remain
entrenched in the teens to 20% range. CAMs show a bit more
scattered activity looking less potent compared to today's, but
enough instability should bring another risk of at least
isolated strong to severe storms.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 159 AM MDT Fri Aug 1 2025

Sunday onwards looks to be hotter and drier across much of the
region as an upper-level ridge move into the Intermountain West and
the moisture fetch from the Pacific Ocean dissipates with the
disruption from the ridge. 700mb temperatures will surge back into
the 17 to 20C range by mid-week, leading to much warmer temperatures
mid-week onwards as the ridge remains in place overhead. Wednesday
and Thursday look to be the hottest day of the week with low- to
upper-90s returning to much of the area as 700mb temperatures rise
into the 18 to 20C range once more. With the warmer and drier
conditions, fire weather concerns will return mid-week, especially
in locations that do not see rainfall over the next couple of days.
The next best chance for precipitation will be next weekend, as an
upper-level trough and subsequent 700mb low are progged to move into
the region. However, this is still over a week out and this
potential will likely change over the next several forecast
packages. Overall, looks like another hot and dry week for much of
southeast Wyoming and western Nebraska.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 538 PM MDT Fri Aug 1 2025

Storms will be mostly likely from KCYS and eastwards through
KBFF,KSNY, and KAIA. These storms could be strong to severe and
include very large hail, strong wind gusts, and even an
isolated tornado. Cloud bases may also drop back down to MVFR
status, alongside heavy rainfall bringing IFR visibility or
worse. Storms also possible all other sites, but should not be
as strong, particularly at KRWL/KLAR where any storm near these
sites will be brief and not likely to be severe. Decks should
then lift this evening, and some low clouds may be possible
tomorrow morning but the threat for low decks is less likely
compared to previous days.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

SHORT TERM...AM
LONG TERM...MM
AVIATION...CG

Hazardous Weather Outlook
National Weather Service Cheyenne WY
234 PM MDT Fri Aug 1 2025

NEZ002-003-019>021-054-055-095-096-WYZ101>119-022045-
Dawes County-Box Butte County-Scotts Bluff County-Banner County-
Morrill County-Kimball County-Cheyenne County-
Northern Sioux County-Southern Sioux County-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-Ferris/Seminoe/Shirley Mountains-
Shirley Basin-Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-Central Carbon County-
North Snowy Range Foothills-Southwest Carbon County-
Sierra Madre Range-Upper North Platte River Basin-Snowy Range-
Laramie Valley-South Laramie Range-South Laramie Range Foothills-
Central Laramie County-East Laramie County-
234 PM MDT Fri Aug 1 2025

This hazardous weather outlook is for portions of panhandle
Nebraska...east central Wyoming...south central Wyoming and
southeast Wyoming.

.DAY ONE...THIS AFTERNOON AND TONIGHT

- There is a Slight Risk (Level 2 of 5) for severe weather
  Friday afternoon and evening east of the Laramie Range. All
  modes of severe weather are possible: hail, winds, tornadoes,
  and flash flooding.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

- There is a Marginal Risk of severe weather for Saturday,
  mainly across western Nebraska. Primary hazards look to be
  hail, wind, and flash flooding.

- Drier and warmer conditions return mid-week and continue
  through the weekend.

.Spotter information statement...

Spotter reports for severe weather and heavy rainfall are
encouraged.

Special Weather Statement
National Weather Service Cheyenne WY
430 PM MDT Fri Aug 1 2025

WYZ117-118-012300-
Central Laramie County WY-South Laramie Range Foothills WY-
430 PM MDT Fri Aug 1 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN LARAMIE COUNTY
THROUGH 500 PM MDT...

At 430 PM MDT, Doppler radar was tracking a strong thunderstorm over
Rocking Star Ranch, or 12 miles northwest of Cheyenne, moving east at
10 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Cheyenne, Happy Valley, Federal, Rocking Star Ranch, Silver Sage
Estates, Ranchettes, Cheyenne Regional Airport, Warren AFB, Frontier
Park, North Cheyenne, and Fox Farm-College.

This includes Interstate 25 in Wyoming between mile markers 11 and
27.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Tornado Watch remains in effect until 1000 PM MDT for southeastern
Wyoming.

&&

LAT...LON 4113 10510 4130 10513 4139 10481 4113 10475
TIME...MOT...LOC 2230Z 258DEG 8KT 4124 10499

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

KM

Preliminary Local Storm Report
National Weather Service Cheyenne WY
519 PM MDT Fri Aug 1 2025

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

0518 PM     Hail             18 WNW Cheyenne         41.24N 105.11W
08/01/2025  M1.25 Inch       Laramie            WY   Trained Spotter

&&

Preliminary Local Storm Report
National Weather Service Cheyenne WY
521 PM MDT Fri Aug 1 2025

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

0519 PM     Tstm Wnd Gst     12 SSE Horse Creek      41.25N 105.09W
08/01/2025  M58 MPH          Laramie            WY   Trained Spotter

&&

Preliminary Local Storm Report
National Weather Service Cheyenne WY
531 PM MDT Fri Aug 1 2025

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

0530 PM     Hail             13 W Cheyenne           41.15N 105.04W
08/01/2025  M1.25 Inch       Laramie            WY   Trained Spotter

&&

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