691
FXUS65 KRIW 181726
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1126 AM MDT Wed Sep 18 2024

.KEY MESSAGES...

- Strong winds off the east slopes of the Absarokas and Bighorns
  through midday.

- Widely scattered rain showers (snow for higher terrain) for
  the northern half of the CWA off and on all day Wednesday.

- Dry conditions Thursday with cooler temperatures and sporadic
  precipitation chances Friday and over the weekend.

&&

.DISCUSSION...
Issued at 1234 AM MDT Wed Sep 18 2024

IR currently depicts a classic comma cloud signature from the
high plains to the northern Rockies with much of the colder
cloud tops out of the state. Radar shows some lingering rain
showers and light snow for the higher terrain across northern
parts of the CWA that will continue to wrap around off and on
throughout Wednesday. The cold front is now well to the east
with ample CAA pushing into the state reinforcing the gusty
westerly winds through the morning hours. Boundary layer winds
have 50 plus knots that could mix to the surface under the ample
cloud cover not capped aloft. The main focus areas for any high
winds will be off the east slopes of the Absarokas funneling
through the Cody foothills, as well as across the Rattlesnakes
to Natrona County. Winds will finally start diminishing towards
noon Wednesday and into the afternoon hours as the gradient
weakens in wake of the occluded front exiting to the east with
the main upper level low. Behind it will be induced ridging for
Thursday that will dry out the state but continue with the
cooler, more seasonable temperatures to end the work week and
over the weekend for the long term.

Next up will be another upper level low making its way down the
west coast towards the Four Corner Region. Models are now
indicating more alignment with one another pushing it further
south with less of an impact to the CWA. Cooler temperatures
will still be had with breezy winds Friday and into the weekend,
but precipitation chances look to be more minimal as the
shortwaves spin around the aforementioned low. Higher terrain
look to be most impacted with some weak mountain snow as well as
some rain showers for south central Wyoming as the low tracks
east across the southern states. The main jet will be cut off to
the north keeping the more potent lows with much colder air
near the Canadian border and into Canada. Longer term forecasts
have much model disagreement with some interesting weather
patterns to come by mid next week all dependent on some
trough/low tracks coming down from the Gulf of Alaska through
the Pacific northwest. Time will tell, so stay updated in the
coming days. All in all, once this current upper level low track
eastward later today, expect calmer yet somewhat unsettled
weather to come keeping the cooler temperatures going forward.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1126 AM MDT Wed Sep 18 2024

Cloud cover and areas of light rain have been wrapping into
northwest and northern Wyoming Wednesday morning within counter-
clockwise flow around an upper-level low over Montana. Also, gusty
southwest surface wind 30G50kts has plagued KCPR and similar speeds
are likely to prevail there through about 22Z/Wednesday before
slowly decreasing by 02Z/Thursday. The counter-clockwise flow
leads to gusty westerly surface wind 15-30kts until around
01Z/Thursday at most other terminals, with 10-20kt winds
lingering longest at KRIW in favored west-northwest flow. As
for precipitation, KJAC will continue to flirt with MVFR/VFR
threshold of 030AGL through mid-afternoon, with VFR likely to
prevail after 21Z/Wednesday. All other terminals to be VFR.
Scattered light rain showers remain favored at KJAC in west-
northwest flow until 03Z/Thursday. KWRL has a less than 30
percent chance of seeing a brief light rain shower from 21Z-
24Z/Wednesday. Other terminals to remain dry. Cloud cover
gradually dissipates and ceilings rise from south to north
tonight. Any lingering light showers decrease between
06Z-12Z/Thursday.

Mountain tops frequently obscured above 10K feet MSL until
06Z/Thursday across the northwest quadrant of Wyoming.

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...
High Wind Warning until noon MDT today for WYZ003-019-020.

&&

$$

DISCUSSION...Lowe
AVIATION...CNJ