Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 012226
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
426 PM MDT Sat Oct 1 2022

.SHORT TERM...(This evening through Sunday night)
Issued at 240 PM MDT Sat Oct 1 2022

An upper/mid level cutoff low is currently centered over the
Idaho/Wyoming border. This will continue to slowly rotate north
through tonight. Accordingly, another day of scattered showers and
thunderstorms is ongoing across most of the area. The best
chances will again be across central and northern Wyoming. Far
southwestern areas will likely see the lowest additional
accumulation today as relatively drier air pushes in. Highs will
be cooler today as 700mb temperatures drop to around 0C this
afternoon. Snow will continue at higher elevations today and
tonight, generally above 9,000 ft.

On Sunday the low will move north over the Wyoming/Montana border.
This will shift the shower focus to northern Wyoming. However, a
relative upper-level jet maxima will pass over southern Wyoming,
which should lead to isolated showers and thunderstorms in
Sweetwater and Natrona counties. Overall a drier day is
anticipated. Temperatures will moderate on Sunday as the cold core
of the system shifts north with the low; highs will generally be
5 to 10 degrees warmer than today.

.LONG TERM...(Monday through Saturday)
Issued at 240 PM MDT Sat Oct 1 2022

The H5 low finally starts to pull east starting Monday, getting
drawn out by easterly flow across Canada and the approach of a
larger trough sweeping southeast from the Canadian Northwest
Territories. It will still be close enough on Monday to bring
continued showers, mainly for northern WY and the I-25 corridor. The
trough picks up speed during the evening, shutting down the last of
the shower activity. The highly amplified pattern remains in place
through the rest of the week, keeping WY in cool northwesterly flow
aloft. This will keep temps near normal, generally in the 60s
during the day and the 30s and lower 40s each night. Models are
still having difficulty with this amplified pattern, though, so
there are differences in any impulses embedded in the longer wave
troughs, and the effect they have on longwave progression. This
considerable difference will keep overall confidence in the extended
periods lower until these impulses get better resolved in all
models.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 425 PM MDT Sat Oct 1 2022

Upper low remains continues to spin just west of the region, drawing
moisture northward across the state. Showers and thunderstorms will
continue for most areas tonight into Sunday. Daytime heating has
allowed cigs in some areas to lift, but will still be variable with
VCTS. Fog formation will be more likely for areas that received
rainfall the last 24 hours. Currently, best chances are KBPI/KPNA,
and main be in the vicinity of KRIW, where fog will be likely stuck
in the valley below the airport. Starting tomorrow, the low moves
north into Montana, allowing some of the southern sites to remain
VFR, with showers limited to northern sites.

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

&&

.FIRE WEATHER...
Issued AT 240 PM MDT Sat Oct 1 2022

Cool and wet conditions will continue as an upper level low rotates
across northwestern Wyoming. The best chances for additional
precipitation through tomorrow will be across northern and central
areas. This will fall as mountain snow above 9,000 ft. Eastern
Sweetwater County through Natrona County will also see some
additional showers and thunderstorms on Sunday, as well as a breezy
wind with gusts near 25 mph in the afternoon. Otherwise, conditions
will be a bit drier overall on Sunday as the low starts to away from
the area.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Myers
LONG TERM...Straub
AVIATION...Straub
FIRE WEATHER...Myers


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