High Wind in Wyoming, June 26, 2026

Area Forecast Discussion
National Weather Service Riverton WY
1203 PM MDT Fri Jun 26 2026

.KEY MESSAGES...

- Warm today with highs ranging from the 80s to low 90s.
  Isolated afternoon virga, showers, and thunderstorm chances
  (15% to 40%) along and east of the Continental Divide. Gusty
  45 to 55 mph outflows are possible even in virga.

- A weather system will bring cooler (highs in the upper 50s and
  60s) and rainy weather to western and northwestern Wyoming
  with showers and some high elevation snow.

- Temperatures will be 5 to 15 degrees cooler compared to today
  across a majority of central, southern,and northern Wyoming on
  Saturday and Sunday. However, gusty 35 to 40 mph winds bring
  elevated to near critical fire weather conditions both
  afternoons.

- A warm up, mostly dry conditions, and breezy winds are
  forecast Monday through the end of the next work week, so
  elevated to near critical fire weather conditions are looking
  more favorable.

&&

.UPDATE...
Issued at 1202 PM MDT Fri Jun 26 2026

Today's forecast largely remains on track for this afternoon and
evening as southwest flow strengthens across Wyoming. 18Z/noon
observations indicate that the drier and warmer air has reached
southwest Wyoming, with dew point readings in the 20s and 30s and
temperatures around 80 degrees Fahrenheit. This translates to
relative humidity values already in the low 20s and teen percent
range. Low level moisture is hanging around a bit longer across
central and northern Wyoming, with dew points in the upper 40s and
50s. These higher dew points are likely due to Thursday's beneficial
rain. As southwest flow strengthens and expands across the state
this afternoon, the air across central and northern Wyoming will dry
out and warm up. Winds will also increase across the entire state
ahead of an approaching late evening cold front. Widespread wind
gusts of 30 to 40 mph are forecast between 2PM and 7PM. These gusty
winds will further aid in drying out the atmosphere, so elevated to
near critical fire weather conditions are anticipated this
afternoon, especially across southern Wyoming.

In addition to the fire weather concerns, the isolated virga,
showers, and thunderstorms potential mentioned in the morning
discussion remains. The greatest chances (15% to 40%) exist along
and east of the Continental Divide, excluding the Wind River Basin.
Given the dry low level air, afternoon LCL's are expected to be in
the 11,000 to 13,000 ft AGL range across the Bighorn Basin and
Johnson and Natrona Counties. With LCL's this high and dew point
depressions in the 40 to 50 degree range, any virga, shower or
thunderstorm, will be capable of 45 to 55 mph gusts as it collapses.
Chances are much less (<10%) across southern Wyoming this afternoon,
but should anything be able to develop gusts of 55 to 60 mph would
be possible. The best time frame for any virga, showers, or
thunderstorms is 1PM to 8PM. As for Saturday, showers are still
forecast across western Wyoming and drier elsewhere. Fire headlines
were considered for Natrona County for Saturday afternoon but
conditions still look borderline, so no headlines were issued at
this time.

&&

.DISCUSSION...
Issued at 138 AM MDT Fri Jun 26 2026

I returned from a vacation about a week ago, and have worked
straight through since then. It seems like I am cursed when it comes
to thunderstorms. Since I went back to work on Friday night,
this is my seventh night. And this is sixth of the seven days
when we have had at least a marginal risk in portions of our
County Warning Area. (June 21st was the only day there wasn't
one). If I didn't have to see another thunderstorm this summer,
I would be delighted. (Not going to happen, but I can wish).
And, what a surprise, we have another one today, although just a
small part of the area.

And this is courtesy of another shortwave that will be rotating into
the area as an upper level low moves onshore in the Pacific
northwest. Coverage should be less then previous days though.
Most activity should be across the northern half of the area.
The season will be southwest flow that will move in ahead of the
low. This will do a few things. One, it will bring the warmest
day we have had in a while to these parts, with many locations
East of the Divide. But in regards to the weather, it should
limit develop of convection to the northern half of the state.
Southwest flow should allow much drier air to move into the
southern half of the state, dropping few points into the 20s and
30s. This should be enough dry air to shut off convection
during the day. The chance of showers and storms looks to be
roughly north of a line from Jackson to Riverton to Casper,
where more humid air will linger today. But even here, the
atmosphere is about 25 percent drier than yesterday so coverage
will be at most 1 out of 3 for any spot except for the
northwestern mountains. Instability parameters are not as
impressive either, with only the northern portions of Johnson,
Natrona and Park Counties having CAPE of more than 500 J/Kg.
This is also the location of limited indices of minus 2 or
lower. Shear also increases as you go further north, hence the
better chance of stronger storms. The main threat today looks to
be strong wind gusts as soundings are showing more inverted V
signatures and most locations will have at least a 40 degree dew
point depression in the afternoon. The third concern is fire
weather. The 700 millibar winds are around 30 knots and these
will mix to the ground for many. Elevated fire weather has a
greater than 4 out of 5 chance in southern Wyoming, but no
highlights since fuels are not critical. The one zone that is
critical that may get close is Washakie County, but it looks to
remain just high enough.

Chances for showers will increase across the west on Friday night as
the flow moves closer. It may take a while to moisten the atmosphere
though, so most POPs were held off until after midnight, and any
steadier showers would likely hold off until after sunrise on
Saturday. Most guidance keeps the low west of Wyoming as it turns
northward and into Montana. That will lead to a northwest to
southeast gradient of precipitation chances across the area, with
the highest obviously in the northwest. It will be quite a contrast,
with western Wyoming having more cloud cover along with cool
temperatures and numerous showers. Meanwhile, continued downsloping
southwest flow will bring another windy and warm day to many areas
East of the Divide. There will likely be a few showers and
thunderstorms around but the chance is only around 1 out of 5 for
most and many areas will see nothing. And with low humidity
remaining, another day of elevated fire weather. I did give a brief
thought of a Fire Weather Watch for Natrona County, but again with
the conditions borderline, we held off for now. And, what a
surprise, wait for it, we have another Marginal Risk, but only for
the far northern portion of our area again. The main threat again
will be strong wind with the rather large dew point depressions.

Cooler air will begin to move into the area on Sunday. It will be
the same general pattern with cooler weather in the west and warmer
weather in the east with the continued downsloping flow. There will
be further showers in the west. However, recent model runs have
shifted the deeper moisture to the west, so amounts have backed off.
It will still be a cool and damp day. And we have to talk about
chance of snow. With the deeper moisture further to the west,
amounts look smaller. However, many locations in the northern
mountains still look to have a greater than 1 in 2 chance of an inch
of snow this weekend into the first part of Monday. The only place
with a higher than 1 in 2 chance of 3 inches are the very highest
peaks of the Wind River Range. Not nearly enough for highlights, but
people heading to the high country should be aware of wet and cold
weather this weekend. Only isolated showers and storms are again
expected East of the Divide.

Things look generally drier next week. We will stuck between a
strong ridge across the eastern United States and a mean trough
across the West Coast. This should keep southwest flow across the
area with gradually warming temperatures. There will be a few
chances of showers and storms with shortwaves moving through, but
exact timing of them remains in flux.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1105 AM MDT Fri Jun 26 2026

VFR conditions prevail through the period, though chances for
showers and thunderstorms could bring brief worsening conditions.
Friday afternoon, showers and storms will be possible across
northern Wyoming terminals, such as KCOD, KJAC, and KWRL, with
lesser chances for KCPR, KLND, and KRIW. Gusty winds 30 to 50 knots
is the main hazard with any shower or storm. These chances diminish
this evening. A push of showers, and potentially storms, moves into
western Wyoming starting around 08z, moving eastwards through
Saturday morning. This brings a chances of rain to KBPI, KPNA, and
KJAC.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued at 138 AM MDT Fri Jun 26 2026

A combination of a gusty wind, humidity falling into the upper
teens and dry fuels will bring elevated fire weather to much of
central and southern Wyoming. A few dry thunderstorms are also
possible. Elevated fire weather continues East of the Divide as
well as southern Wyoming with a continuation of low humidity and
a gusty southwest wind continues.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

UPDATE...Gerhardt
DISCUSSION...Hattings
AVIATION...Wittmann
FIRE WEATHER...Hattings

Special Weather Statement
National Weather Service Riverton WY
232 PM MDT Fri Jun 26 2026

WYZ011-262100-
Southeast Johnson County-
232 PM MDT Fri Jun 26 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN JOHNSON COUNTY
THROUGH 300 PM MDT...

At 232 PM MDT, Doppler radar was tracking a strong thunderstorm near
Fort Reno Historical Site, which is 18 miles northeast of Kaycee,
moving northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could blow around unsecured objects. Minor hail
         damage to vegetation is possible.

This strong thunderstorm will be near...
  Fort Reno Historical Site around 235 PM MDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4381 10602 4372 10633 4388 10645 4409 10606
      4402 10601 4382 10601
TIME...MOT...LOC 2032Z 240DEG 21KT 4384 10630

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

TL

Special Weather Statement
National Weather Service Riverton WY
235 PM MDT Fri Jun 26 2026

WYZ009-020-262100-
Bighorn Mountains Southeast-Natrona County Lower Elevations-
235 PM MDT Fri Jun 26 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL NATRONA COUNTY
THROUGH 300 PM MDT...

At 235 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles southwest of Hiland, which is 36 miles southeast of Shoshoni,
moving northeast at 35 mph.

HAZARD...Wind gusts up to 50 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.

This strong thunderstorm will be near...
  Hiland around 240 PM MDT.
  Waltman Rest Area around 245 PM MDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4305 10690 4288 10737 4292 10741 4292 10744
      4295 10750 4304 10750 4316 10751 4325 10733
      4324 10730 4326 10730 4329 10723
TIME...MOT...LOC 2035Z 232DEG 35KT 4301 10744

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Wittmann