470
FXUS65 KRIW 051903
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1203 PM MST Thu Nov 5 2026

.KEY MESSAGES...

- Dry conditions and seasonal temperatures prevail for most
  areas through Friday. However, there is a 10 to 20 percent
  chance for light rain or snow showers over portions of south
  Lincoln and Sweetwater Counties starting late Thursday evening
  and continuing through mid-morning Friday.

- Dry conditions and generally light winds continue through the
  weekend.

- Temperatures climb to above average Saturday and persist into
  the middle of next week. The warmest temperatures arrive
  Sunday, with many areas at least 10 degrees above seasonal
  averages.

&&

.UPDATE...
Issued at 1203 PM MST Thu Nov 5 2026

Morning fog and low clouds in far northwest Wyoming have eroded
as of midday, but linger across western Sweetwater County. These
clouds fade early Thursday afternoon ahead of an approaching
trough. This trough is nearing the western Wyoming border and
will quickly replace an upper ridge transiting the state today.
Clouds steadily increase from west-to-east this afternoon and
evening as an elongated mid-level moisture axis associated with
the trough spreads across the region. This narrow axis allows
for clearing to begin over Yellowstone and the far west just
prior to sunrise Friday. The clearing line makes its way
through most, if not all, of the forecast area by midday Friday.
Dry conditions prevail over almost the entire region with the
exception being the far southwest. A few showers could occur
over south Lincoln County beginning early Thursday evening
before spreading into Sweetwater County by early Friday
morning. Isolated light showers or virga linger over this region
until clearing begins between 15Z-18Z/Friday. The overnight
cloud cover keeps low temperatures Friday morning at least a few
degrees warmer than those of Thursday morning. Only surface
wind of significance will be a south to southwest wind 15 to 25
mph Thursday afternoon from South Pass to Casper and northward
through Johnson County.

&&

.DISCUSSION...
Issued at 153 AM MST Thu Nov 5 2026

Another day of quiet weather returns to the Cowboy State today, as
an area of high pressure shifts over eastern MT/WY and the western
Dakotas. The main impacts will be temperatures rising a few degrees
above normal in the Bighorn Basin and Natrona County and as high as
13 degrees above normal over Johnson County today. Additionally,
southwest winds with gusts up to 20 mph will occur from South Pass
to eastern Johnson County this afternoon.

A trough will move over the region on Friday, shifting the area of
high pressure over the Dakotas and Upper Midwest. Very light rain
showers will be possible over Sweetwater County between 11Z and 20Z
along the tail end of the trough. West to southwest winds with gusts
of 20 to 25 mph will impact most areas Friday afternoon in the wake
of the trough. Otherwise, temperatures will return to more seasonal
levels. A broad ridge will then build over much of the Intermountain
West and extend over the Northern Rockies by Saturday keeping
conditions dry. Above normal temperatures return to the Bighorn
Basin and Johnson/Natrona counties Saturday, becoming more
widespread across the CWA on Sunday. A fast moving trough will pass
over the northern half of the state Monday as the ridge folds over.
The flow pattern will be more zonal Monday and Tuesday, before
another ridge returns over the Northern Rockies Wednesday and
remains in place Thursday. Conditions look to remain dry through the
next 7 days, apart from the aforementioned light showers possible
Friday morning.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1013 AM MST Thu Nov 5 2026

Fog has been persistent in far western valleys this morning, but
is finally eroding at KJAC and KAFO. Low clouds should quickly
thin out, with only high clouds through the rest of the day.
KRKS fog has been expanding the past couple hours, so need to
expand the timing into this afternoon. KRKS clouds should
finally thin once the southwest winds start back up around 21Z.
While moisture remains in place at these locations overnight,
there may be just enough of a breeze to keep things more mixed
tonight, so currently have just low clouds and not fog for the
time being. Remaining sites across western and central Wyoming
remain VFR with only passing high cirrus this afternoon and
tonight, before mostly clear skies return on Friday.

&&

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

&&

$$

UPDATE...CNJ
DISCUSSION...LaVoie
AVIATION...Straub