Severe Thunderstorm Warning 174, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
515 PM MDT Sat Jun 27 2026

.KEY MESSAGES...

- Isolated strong to severe thunderstorms are possible over the
  Nebraska panhandle Saturday afternoon and evening.

- Critical fire weather conditions are ongoing Saturday over
  much of southeast Wyoming with strong southwest winds, low
  humidity, and warm to hot temperatures.

- A few showers moving in from the west this afternoon will have
  the potential to produce gusty and erratic winds in southeast
  Wyoming.

- Elevated fire weather conditions continue Sunday, with more
  widespread critical conditions possible Monday. Elevated fire
  weather conditions will continue for much of the week ahead.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 131 PM MDT Sat Jun 27 2026

An unseasonably strong upper level low is circulating over the
Pacific northwest today, bringing a change in the weather after the
stormy pattern over the last several days. Over southeast Wyoming,
dry air in the dry slot of this upper level low is mixing down, and
pushing the surface dryline eastward. While this has been slower
than modeled earlier today, all of southeast Wyoming except
Torrington and Lusk have seen dewpoints plummet. Gusty southwest
winds in combination are leading to increasing fire danger. While
there is some uncertainty concerning how the recent rainfall might
have affected fuel conditions, a Red Flag Warning was issued for the
Wyoming High Plains out of caution, as weather conditions are
certainly meeting criteria. Fuels west of the Laramie range are
still in green-up status, so no headlines will be issued there.
However, fairly significant weather conditions are expected with
southwest winds gusting 50+ mph and RH dropping to around 10%. In
addition, a cool front will arrive late this afternoon (pushing in
around 6PM to our western zones). Expect an abrupt wind shift to the
west or WNW. In addition, expect to see some high-based showers
developing along the boundary and pushing into Carbon and Converse
counties. These will have the potential to produce locally gusty and
erratic winds. With the strong background flow already in place, it
won't take much to exceed 60 mph with this activity.

Plentiful low-level moisture is still in place east of the dryline,
which has been slower to advance than expected earlier. With
dewpoints still close to 60 degrees and temperatures warming into
the 80s or even low 90s, we have ample instability in place east of
the dryline. There is still a bit of CIN remaining as of this
writing, but models are in fairly good agreement burning this off by
3PM or so. Once that happens, expect to see some convection
developing along the dryline and moving off to the northeast.
Vertical wind shear isn't too strong today, but it is sufficient to
get a few strong to severe thunderstorms going. The risk area today
is confined to those east of the dryline, so mainly just the
Nebraska panhandle. Storms may take a moment to get going too, so
the Chadron to Alliance corridor is the only portion included the
Level 2 of 5 (Slight) risk for severe weather by the Storm
Prediction Center today. Thunderstorm potential will wind down
around 9PM.

A cool front will push through the area from the northwest this
evening, shifting winds abruptly to the west or WNW. Temperatures
should cool down to near seasonal averages by Sunday morning. Sunday
will be a touch cooler, and thus slightly higher humidity. Fire
weather conditions will still be elevated, but concerns for critical
conditions are confined to Laramie County at this time. The
thunderstorm threat will also be more limited Sunday. We'll have a
frontal boundary stalled straddling our area through the day, but by
the late afternoon or evening hours the trough to our northwest will
initiate some warm air advection overtop the boundary. The front
will simultaneously be pulled into a developing surface low pressure
system over northeast Colorado. Forecast soundings are rather
unimpressive in instability, but we may still see some scattered
showers and thunderstorms go up along this boundary (probably
located from Wheatland to the SW corner of South Dakota). With the
latest update, the Storm Prediction Center pulled the Marginal risk
back to the north somewhat, which seems reasonable in the drier
environment. Expect a fairly windy night across much of the area as
the lee cyclone lifts off to the northeast. An unseasonably strong
surface pressure gradient will be positioned across the area Sunday
evening through Monday morning.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 303 PM MDT Sat Jun 27 2026

On Monday, our area will be sandwiched between a powerful upper
level low over the northern Rockies and a broad upper level ridge
over the southeastern US. An unseasonably tight pressure and height
gradient will be present over the area in between these two systems,
producing widespread gusty winds. 700-mb height gradients from Craig
to Casper reach 73 m by Monday midday per the GFS, which would be
high in mid winter, let alone late June. As usual, the GFS is the
most aggressive model on the 700-mb winds, but this presents a
decent ceiling for wind potential. Expect fairly widespread winds of
at least 40 to 55 mph, with some potential (perhaps 30%) for winds
to exceed high wind criteria in the typical wind prone areas plus
Converse County. Temperatures will be a little cooler Monday across
the area, preventing RH from reaching extremely low values. Still,
widespread critical fire danger will be favored.

The upper level low will eject to the east by Tuesday, reducing the
gradients and thus the wind speeds across our area Tuesday onwards.
Expect a gradual warming trend through the week ahead as the broad
ridge dominating the eastern two thirds of the country expands
westward. Tuesday and Wednesday will probably see temperatures
fairly close to seasonable averages, increasing to above average by
Thursday and Friday. Winds look marginal for Red Flag Warnings
during this period, but it would not be surprising to see wind
speeds increase as we get closer. Fire weather concerns will be at
least elevated for much of the week. Most afternoons and
evenings during the week will bring potential for a few isolated
showers and thunderstorms, but it is difficult to determine
which days will be most noteworthy, and what the storm hazards
might be.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 515 PM MDT Sat Jun 27 2026

Showers and thunderstorms are building across the CWA and may impact
the Nebraska terminals at varying times throughout this afternoon.
Most of this activity should be winding down by 03Z Sunday. This
will be the primary aviation concern for those sites. Elsewhere,
gusting winds will continue to impact southeast Wyoming sites for
the next several hours as well. Look for the winds to diminish
through the evening into the overnight hours across all terminals to
generally less than 10 knots by 10Z Sunday. However, this lull in
winds will be short-lived as they will ramp up again near the tail
end of this TAF period with gusts 20 to 30 knots.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ417>419-
     430>433.
NE...None.

&&

SHORT TERM...MN
LONG TERM...MN
AVIATION...RZ

Special Weather Statement
National Weather Service Cheyenne WY
258 PM MDT Sat Jun 27 2026

NEZ095-WYZ102-272130-
North Sioux NE-Niobrara County WY-
258 PM MDT Sat Jun 27 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN SIOUX AND
SOUTHEASTERN NIOBRARA COUNTIES THROUGH 330 PM MDT...

At 258 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles east of Lusk, moving northeast at 30 mph.

HAZARD...Wind gusts up to 50 mph and penny size 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...
Lusk.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4265 10428 4271 10448 4299 10428 4287 10395
TIME...MOT...LOC 2058Z 223DEG 27KT 4274 10431

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Goatley

Special Weather Statement
National Weather Service Cheyenne WY
441 PM MDT Sat Jun 27 2026

NEZ002-095-WYZ102-108-272315-
Dawes NE-North Sioux NE-Goshen County WY-Niobrara County WY-
441 PM MDT Sat Jun 27 2026

...STRONG THUNDERSTORMS WILL IMPACT NORTHWESTERN DAWES...NORTHWESTERN
SIOUX...EASTERN NIOBRARA AND NORTHEASTERN GOSHEN COUNTIES THROUGH 515
PM MDT...

At 441 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms 11 miles north of Van Tassell, or 16 miles east of
Lusk, moving northeast at 65 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Lusk, Harrison, Manville, Van Tassell, Montrose, Redbird, Lance
Creek, Toadstool Geological Park and Campground, and Niobrara County
Fairgrounds.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 1100 PM MDT for
the Panhandle of Nebraska.

&&

LAT...LON 4321 10405 4300 10405 4299 10340 4250 10399
      4265 10477 4332 10443
TIME...MOT...LOC 2241Z 220DEG 55KT 4283 10415

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Goatley

Special Weather Statement
National Weather Service Cheyenne WY
526 PM MDT Sat Jun 27 2026

NEZ002-095-272345-
Dawes NE-North Sioux NE-
526 PM MDT Sat Jun 27 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN DAWES AND
NORTHEASTERN SIOUX COUNTIES THROUGH 545 PM MDT...

At 526 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles east of Montrose, or 26 miles west of Chadron, moving northeast
at 25 mph.

HAZARD...Wind gusts up to 50 mph and penny size 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...
Toadstool Geological Park and Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 1100 PM MDT for
the Panhandle of Nebraska.

&&

LAT...LON 4279 10344 4287 10366 4300 10360 4300 10323
TIME...MOT...LOC 2326Z 205DEG 24KT 4290 10351

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Goatley