295
FXUS65 KRIW 050433
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1033 PM MDT Thu Jun 4 2026

.KEY MESSAGES...

- Elevated to near-cricital fire weather conditions occur
  Friday and through this weekend, with widespread gusty winds
  (20 to 40 mph) and low humidity (less than 15 percent).

- Hot Saturday, with highs in the 80s west of the Divide, and
  mid-to- upper 90s east of the Divide. Cooler air moves in for
  Sunday, dropping highs around 10 degrees and bringing slight
  (15 to 40 percent) rain chances, mainly for northern Wyoming.

&&

.UPDATE...
Issued at 956 AM MDT Thu Jun 4 2026

No major changes to the forecast with this update. Current water
vapor shows the shortwave moving through northern Wyoming at this
time, with a decent number of clouds. This feature tracks eastwards
through this evening. The main result of this is the chance for
showers and thunderstorms, some of which could be strong to severe.
The better threat for strong storms exists north and east of the
area, but northern Johnson County could see a strong storm between
3pm and 7pm; the main hazards are winds up to 60 mph and small hail.

&&

.DISCUSSION...
Issued at 243 AM MDT Thu Jun 4 2026

KRIW radar noting very light echoes this morning moving across
northern WY from the northwest Parks into the Bighorn Range.
Most of these are very high-based, and dry air near the sfc is
keeping most precip from actually reaching the ground. These
showers are due to a passing shortwave across western WY north
into MT. The shortwave will be mostly through the area by noon,
but showers and thunderstorms may linger across the northern
Bighorns and northern Johnson County into early afternoon. With
daytime heating and instability, some development of strong
thunderstorms could build quickly in these areas before sweeping
quickly to the northeast by mid- afternoon. Main threat with
these storms would be gusty downburst winds due to very dry sfc
conditions.

Farther to the south away from the shower activity, the pressure
gradient around this system is tighter, which will result in
some gusty southwest winds this afternoon. Forecast gusts range
from 30 to 40 mph from KRKS across the Green Mountains into
Natrona County. This, along with dry air already in place
across the state, will lead to near-critical fire weather
concerns this afternoon. With most areas still in spring
greenup, fuels are less receptive, so Red Flag Warnings will not
be posted, but any fires that do spark will still have erratic
behavior. Any burning is not advised today.

Once this system moves off this evening, the pattern buckles
across the Northern Rockies as a large trough drops down the
West Coast. This puts most of WY in favorable ridging,
deflecting systems away and allowing temperatures to soar. With
H7 temps still forecast to reach 16 to 18C, sfc temps will jump
well into the 80s west of the Divide and into the 90s east of
the Divide. Models have been trending upwards the past few days,
with the latest forecast getting closer to daily record highs,
and a couple areas within striking distance of 100 degrees.

Longer term forecast notes the West Coast trough shifting
farther east, knocking temperatures back down closer to normal.
This will also shift better moisture into western WY, bringing a
better chance for daily thunderstorms along the higher
elevations of northwestern WY.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1031 PM MDT Thu Jun 4 2026

Mostly SKC skies currently in place this evening. The lower
clouds that were expected at KCPR dispersed earlier as the cold
front reach the Divide around 03Z. The cold front will reach
KRIW shortly after the start of the forecast, washing out after
sunrise. Conditions will remain dry through the TAF period.
Most terminals will have wind gusts around 20kt by 17Z, becoming
light (10kt or less) again by 02Z.


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

&&

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

&&

$$

UPDATE...Wittmann
DISCUSSION...Straub
AVIATION...LaVoie