047 
FXUS65 KRIW 230345
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
945 PM MDT Wed Oct 22 2025

.KEY MESSAGES...

- A largely dry trend continues through Saturday morning with
  high temperatures 5 to 12 degrees above normal.

- A weather system approaches Wyoming Saturday afternoon with a
  greater than 90% chance of 40 mph gusts from South Pass to
  Casper. Accumulating mountain snow along and west of the 
  Divide is likely (95% chance) Sunday through Tuesday morning.
 
- Colder temperatures on Monday and Tuesday with widespread
  values 5 to 15 degrees below normal.

&&

.UPDATE...
Issued at 1229 PM MDT Wed Oct 22 2025

The forecast remains unchanged this afternoon. 18Z satellite water 
vapor imagery shows the upper level low slowly moving onshore the 
central California coast. As the low shifts east across the Four 
Corners region, precipitation chances (5 to 10%) are confined to far 
southern Wyoming late tonight and Thursday morning. Anything that 
does materialize would be very isolated as support aloft and 
deep moisture remains limited. The most likely (95% +) evidence 
of this upper low will be increased cloud cover this evening 
through Thursday morning. Overnight clouds will limit 
radiational cooling effects and keep low temperatures 5 to 10 
degrees warmer Thursday morning compared to the lows this 
morning. Clouds gradually clear through the Thursday afternoon 
hours. Apart from the very low precipitation chances Thursday 
morning, confidence is high (95 to 100%) in dry weather through 
Saturday morning.

&&

.DISCUSSION...
Issued at 100 AM MDT Wed Oct 22 2025

WV imagery continues to show strong subsidence across the CWA
and upper Rockies with only a few upper level clouds evident on
IR for northwestern portions of the state. Otherwise, upper 
level ridging continues to be set in place for Wyoming building 
from the southwest due to increasing convergence aloft. A closed
upper level low off the southern California coast will scoot 
east through the Four Corner Region through Thursday with very 
minor precipitation chances near the southern border (<5-10%) 
Wednesday night. Otherwise, a mainly tranquil rest of the work 
week is set in place with a slight warming and dry trend through
Friday. Temperatures will push 5 to 10 degrees warmer than 
average for this time of year nearing the end of October. 

Focus will shift to the next storm system that will begin to
affect the higher terrain west of the Divide Saturday night into
Sunday extending from a strong low over the Gulf of Alaska. This
will push east of the Divide Sunday night into Monday as the
associated cold front pushes through. Although details are not
concise at this point in time, HREF ensemble data along with
many of the deterministic models indicate impacts for much of
the CWA. Systems of this path tend to produce higher snow
amounts for western mountains and lower precipitation chances 
to the east. What is for certain will be stronger southerly 
winds ahead of the aforementioned cold front Saturday and Sunday
for the weekend with indications of gusts over 40 mph at the 
minimum. Stay tuned for updates in the coming days for a finer 
tuned forecast with this upcoming system.

Otherwise, expect cooler temperatures Monday and for much of
next week seeing more seasonable to 5-10 degrees cooler than
average for the last few days of the month. A steady flux of mid
to upper level moisture will extend into Tuesday before the
precipitation exits the CWA into the upper High Plains and
Dakotas. Longer term model solutions are in the ballpark of
consensus of ridging to build back in for the middle to end of
next week looking at a more pleasant end of the month.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 945 PM MDT Wed Oct 22 2025

Terminals remain VFR through 06Z/Friday. High clouds spin north
across the region tonight and Thursday . Southwest Wyoming 
cloud may have a few virga showers tonight, but no impacts 
result. Wind directions remain largely driven by typical diurnal
patterns, with speeds remaining less than 8 knots through 
midday Thursday. As the upper low moves east, afternoon surface 
winds become northwest to northerly at 7 to 10 knots for most 
terminals. Winds then becoming largely diurnal again shortly
after sunset on Thursday.

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

&&

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

&&

$$

UPDATE...Gerhardt
DISCUSSION...Lowe
AVIATION...Hattings