Casper, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

221
FXUS65 KRIW 190206
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
806 PM MDT Thu Jun 18 2026

.KEY MESSAGES...

- Warm, dry, and breezy conditions may lead to elevated fire
  weather conditions across portions of the state again on
  Friday.

- An approaching disturbance looks to bring widespread chances
  for showers and thunderstorms over the upcoming weekend. The
  best chances remain along the Continental Divide and areas
  east, especially across the Bighorns and Absarokas.

- The first week of summer is looking quite warm with daily
  chances for showers and thunderstorms.

&&

.UPDATE...
Issued at 1215 PM MDT Thu Jun 18 2026

Not much to update regarding the forecast as warm and dry
conditions will persist today into Friday. This will keep
elevated to near critical conditions possible during the
afternoon and evening today and tomorrow. A stray shower or two
cannot be ruled out Friday afternoon/evening mainly over
portions of far southwestern WY. Otherwise, the focus turns to
the weekend, which looks to bring the next chance for showers
and thunderstorms. Models remain in good agreement with the best
chances for precipitation being across central and northern WY.
Locations such as the Absarokas and Bighorns currently look to
have the best chances for wetting rains. The first week of
summer looks to be on the warm side with chances for showers and
thunderstorms possibly arriving by the middle of the week.

&&

.DISCUSSION...
Issued at 214 AM MDT Thu Jun 18 2026

A pleasant day is on tap today, with seasonal temperatures and
mostly sunny skies. The one negative aspect will be northwest winds
gusting up to 30 mph over areas west of the Divide after 18Z. Fire
weather conditions will continue to be elevated to critical this
afternoon, with the highest concern being over southern portions
where the aforementioned winds will combine with humidity values as
low as 8%.

The rest of the forecast remains on track with little changes from
previous packages. A ridge will build over the region from the west
Friday, marking a return for temperatures in the upper 80s to near
90 degrees. Fire weather conditions will continue to be elevated to
critical, with critical RH values (<15%) occurring across areas west
of the Divide, including the western valleys, and central portions
of the CWA. Mid to high clouds will begin to increase, in advance to
the incoming remnant Pacific low. There is a 10% chance for a virga
shower to occur under these clouds through the afternoon.

Chances for precipitation return for the weekend, as the Pacific low
move over the region. Northern portions of the CWA look to have the
best chances to receive any precipitation, with forecasted rainfall
amounts trending downward slightly between 0.25" to 0.50" over
Saturday, Sunday and Monday. Locally heavy rain remains possible
from these storms, as precipitable water values of 0.60" to 1" are
still forecasted. Precipitation chances could linger into Monday, as
a Canadian cold front moves over the area. Dry conditions return to
the region Tuesday, as a strong area of high pressure develops over
the Desert Southwest. Initial indications suggest that shortwaves
will move over the PACNW/Northern Rockies from Wednesday to Friday,
keeping precipitation chances up and the ridge suppressed to the
south.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 514 PM MDT Thu Jun 18 2026

VFR conditions prevail at all terminals through 00Z/Saturday. West-
northwest flow aloft gradually begins to back toward the west and
eventually southwest ahead of a Pacific weather system set to arrive
for the weekend. Initially, high cloud cover spreads across the area
tonight and Friday morning. There could be enough mid-level moisture
to set off very isolated showers over southwest Wyoming late Friday
afternoon. At this time, no impacts to west of the Continental
Divide terminals. As for wind, ongoing west-northwest wind gusting
18-26kts decreases 01Z-02Z/Friday. Westerly surface wind 14-22kts
returns to the western terminals between 18Z-20Z/Friday. Terminals
east of the Divide see a northerly wind receive a secondary surge
Thursday evening as winds gust 14-22kts. These speeds diminish
between 07Z-10Z/Friday leaving northeasterly wind of 10kts or less
by 12Z/Friday, which persist through Friday.

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

&&

.FIRE WEATHER...
Issued at 214 AM MDT Thu Jun 18 2026

Elevated to critical fire weather conditions continue today,
with critical RH values across southern zones, as well as zones
280 and 283. West-northwest winds, with gusts up to 30 mph will
be confined to areas west of the Divide in the afternoon.
Northeasterly winds increase over zones 280/281 after 1900, with
gusts up to 30 mph. These winds will slowly decrease overnight
tonight, ending by sunrise Friday morning.

Similar conditions return Friday, with westerly winds gusting up
to 25 mph being mainly confined over areas west of the Divide.
There will be a 10% chance for a virga shower across the area
through the afternoon.

&&

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

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...LaVoie
AVIATION...CNJ
FIRE WEATHER...LaVoie