Riverton, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

613
FXUS65 KRIW 211105
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
405 AM MST Thu Nov 21 2024

.KEY MESSAGES...

- Snow showers in the northwest today with windy conditions
  again around Casper.

- A Pacific system will bring light to moderate snow to western
  Wyoming on Saturday.

- Much of next week looks unsettled, although details in timing
  of precipitation remain uncertain.

&&

.DISCUSSION...
Issued at 236 AM MST Thu Nov 21 2024

Things are mainly quiet this morning with ridging building over the
Cowboy State. We do have a couple of minor concerns for today. The
first is for the gusty wind, which is continuing tonight from Muddy
Gap through Casper with a decent pressure gradient continuing across
the area. High wind is not expected for the most part, with
probabilistic guidance giving at most a 1 out of 5 chance of wind
gusts past 50 mph, and even there it would be over the higher
elevations with little impact. A place like Outer Drive south of
Casper could see a couple of wind gusts past 50 mph, but this would
be the exception rather than the rule. The other minor concern is
some snow showers across the northwestern mountains, but only the
higher elevations should see accumulations and these would only top
out at an inch or two. With flow turning southwest and the air mass
over the area modifying somewhat, temperatures should average around
3 to 5 degrees warmer than yesterday. Tomorrow, snow showers
will end across the west in the morning. With the ridge axis
over the area, wind should decrease for most locations as well.
Temperatures will also average above normal.

Things become more active on Saturday as the strong system that
brought the wind and rain to the Pacific Northwest moves toward
the state. At this point, this does not look like a major
storm. The system looks to weaken and may split before reaching
the area. The main effects will once again be across western
Wyoming. The models continue to trend downward with amounts as
well. The areas that expect the most snow will once again be the
northwestern mountains, mainly southern Yellowstone and the
Tetons. Most ensemble guidance gives a greater than 4 in 5
chance of 6 inches or more of snow from Saturday into Saturday
night with a smaller area of around a 1 in 2 chance in the Salt
and Wyoming Range. As of now, the chances of warning level
amounts are basically non-existent. So, if any highlights are
needed, it is looking more like advisories. The valleys should
only see small accumulations and with 700 millibar temperatures
starting as high as 0 degrees Celsius, it may start as rain
before changing to snow as the front moves through. Little
precipitation is expected east of the Divide, with a mild day
expected ahead of the front.

Sunday has trended drier across the area with temperatures returning
to normal levels. The main area of concern on this day looks to be
across southern Sweetwater County, where some residual moisture
and some jet energy may bring some light snow. This should
remain south of Interstate, 80 so for now impacts would be
limited. Another piece of energy may approach Monday and bring
another round of snow, again, mainly to areas west of the
Divide. The pattern looks to remain active through Wednesday
with a trough remaining over the area. There are a lot of moving
parts with areas of energy though, so details are still
uncertain. Temperatures will average close to normal through
much of next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 400 AM MST Thu Nov 21 2024

VFR conditions are expected to prevail at terminals through the
TAF period. If there is an exception, it will be at KJAC if
showers are able to move off the surrounding mountains.
Have added a PROB30 group between 02Z and 05Z as a result, for
marginal MVFR conditions with snow. Otherwise, KCPR will
continue to see a southwest wind gusting near 30 knots through
much of the day today.

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.

&&

$$

DISCUSSION...Hattings
AVIATION...LaVoie/Myers