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000
FXUS65 KRIW 261138
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
538 AM MDT Fri Apr 26 2024

.KEY MESSAGES...

- Showers and isolated thunderstorms today and Saturday, most
  numerous in central and southern Wyoming. The steadiest
  precipitation will be tonight,

- Snow is likely in the mountains, with the heaviest in the Wind
  River and Absaroka Ranges.

- Remaining rather unsettled through Wednesday, with a few
  chances for showers and the potential for strong wind Monday
  through Wednesday.

&&

.DISCUSSION...
Issued at 316 AM MDT Fri Apr 26 2024

The pattern looks rather active over the next few days. Radar
currently shows some showers mainly across Johnson and Natrona
County as I write this around 2 am. And today looks rather damp as
we will be under the influence of two low pressure areas. The first
is a vertically stacked, slow moving low that is moving out of
Colorado and into Nebraska at this time. The second is now moving
into the Pacific Northwest and will close off over the Great Basin
tonight and into Saturday. This will turn low level flow east to
northeast across much of the area and bring in moisture.  There are
some changes this morning though. For one, the QPF has trended down
across portions of the area, especially further east and north in
places like Buffalo where the core of the moisture would be further
south. Today looks to be more convective, with isolated
thunderstorms possible in most areas, but the chance of any spot
seeing one is 1 in 3 or less. The steadiest. more stratiform
precipitation still looks to be tonight, when moisture flow
would be the deepest. The highest amounts still look to occur in
the favored east to northeast upslope locations, especially
from the east slopes of the Absarokas to the Wind River Range to
to Salt and Wyoming Range. Heavier amounts are also possible in
southern Wyoming which will be where the best convergence will
set up. In the lower elevations, the most favored areas, like
Lander, Dubois and even Rock Springs have at least a 1 in 2
chance of picking up a half an inch of rain or more. Amounts
would then generally decrease further north and east away from
the deepest moisture. Temperatures will be cooler today, but not
cold given the Pacific nature of the air mass.

Now on to the S word, snow. With 700 millibar temperatures expected
to remain at minus 3 or warmer, snow accumulation would be largely
restricted to the mountains, with snow levels generally 7500 feet or
higher. We can`t rule out a small accumulation of snow in places
like Dubois or Lander if precipitation rates are very heavy, but
accumulation would likely only be on non-paved surfaces. The
heaviest snow still looks to fall in the Wind River Range, where
areas above 10000 feet may pick up 2 feet of new snow, with around a
9 in 10 chance of over a foot of snow in the highest elevations.
We will maintain the Winter Storm Warning here. The advisory for the
Absarokas will also be continued, but impacts here would be less,
with less than 1 in 3 chance of a foot of snow or more.

Unsettled weather will continue into Saturday, although intensity
should be less as the low moves away. A new wrinkle is what may
happen Saturday evening as the trailing trough axis swings through
western Wyoming. Some ensemble solutions are putting advisory
amounts of snow in places like the Salt and Wyoming Range. There is
poor agreement on this though, with less than a 1 in 2 chance of
reaching advisory criteria. This, plus the fact that impacts would
be limited, no new highlights will be issued at this time.

Things become somewhat, emphasis on somewhat, less active after
that. A few showers will linger into Sunday but coverage will be
about 50 percent less than previous days. The first part of the new
workweek will feature mainly zonal flow. A couple of shortwaves will
pass through the flow, most likely on Monday and Wednesday. These
may bring a few showers, especially to northern portions of the
area. Details on how far they reach are difficult to determine
at this time though. The main concern on these days may turn out
to be strong to potentially high wind. Flow is fast over the
area and the jet will be overhead, helping to enhance downward
momentum, especially across the southern half of the state. Way
too early for details, but it could be a few days of securing
things like trash cans, trailers and toupees. More settled
weather is then expected for the end of next week as ridging
builds into the area. Temperatures through much of next week
should average near to slightly below normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 533 AM MDT Fri Apr 26 2024

The continuing unsettled weather pattern has kept scattered light
rain showers across central Wyoming through the overnight hours.
Coverage of precipitation will increase through the morning, with
all terminals favored to see shower or thunderstorm impacts this
afternoon and evening. Brief MVFR conditions can be expected with
this activity through the afternoon, though KCOD and KWRL are likely
to see longer periods of MVFR ceilings. Ceilings will generally
trend lower near the end of the period, with more persistent MVFR
conditions expected for most terminals into Saturday morning.
Frequent mountain obscurations are expected through the period.

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

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from noon today to 3 PM MDT Saturday
for WYZ002.

Winter Storm Warning from 6 PM this evening to 9 PM MDT
Saturday for WYZ015.

&&

$$

DISCUSSION...Hattings
AVIATION...Myers