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000
FXUS65 KRIW 091721
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1121 AM MDT Tue Apr 9 2024

.KEY MESSAGES...

- Rain and snow showers are possible Tuesday and Wednesday,
  mainly across northern and western Wyoming.

- The period from Thursday into the weekend looks mainly dry
  with above normal temperatures.

- An unsettled and cooler weather pattern may return next week.

&&

.DISCUSSION...
Issued at 245 AM MDT Tue Apr 9 2024

Things are mainly quiet across western and central Wyoming overnight
tonight (finally!). And although my forecast busted a bit yesterday,
it was a good bust as clouds thinned and allowed for more (but
certainly not all) locations to see the solar eclipse yesterday. We
will be entering a quieter (but not completely quiet) weather
pattern over the next several days.

Northwest flow will be in place over the area through Wednesday, and
a couple of waves will be moving through the flow. The first will
move into the north during the midday hours and move across the
area through the night. The system does not have a lot of
moisture to work with though. There is however, some jet energy
with it in the form of an 80 knot jet streak. This could enhance
precipitation rates a bit and could lead to some banded
precipitation, of the rain or snow variety. There are also some
negative lifted indices across northern Wyoming and this may be
just enough instability for a thunderstorm or two, although the
chance at any location is less than 1 out of 5. A second wave
will move further east but could be just close enough for some
showers on Wednesday, mainly across Natrona and Johnson
Counties. As for any potential highlights, chances for advisory
amounts of snow are 1 in 5 at best, and these would be in areas
with few people, roads or impacts, like the northern Bighorns.
So, no highlights on this day. Temperatures will remain below
normal through Wednesday with a bit of a breeze.

We should then flip the switch back into Spring on Thursday with a
nice day with near normal temperatures as ridging builds over
the Cowboy State. The forecast beyond this is in a bit of flux.
There is a very clear slower trend with the next more
substantial system that was originally expected as early as
Friday has now been substantially delayed at least until Sunday
night and possibly until Monday. Until then, expect southwest
flow and temperatures averaging well above normal with mainly
areas seeing high temperatures well into the 70s. A few of the
warmer spots, like Greybull and Worland, may see temperatures
touch the 80 degree mark om Friday or the weekend. There will be
a bit of a breeze at times, and this could lead to elevated
fire weather at times during this time frame. Some guidance is
also indicating a couple of week shortwaves and possibly just
enough moisture for a stray shower or thunderstorm. But again,
this would be isolated, with maybe a 1 in 4 chance at best. Most
areas at the point should stay mainly dry from Thursday through
the weekend.

It does look interesting early next week as we could come under the
influence of a pair of upper level lows, one moving in from
California from the south; and another moving in from British
Columbia. How they interact and any details in regards to
impacts or precipitation amounts are anyone`s guess this far
out though. It may remain unsettled much of next week as a
blocking ridge may set up in the eastern United States, keeping
the northern Rockies under a trough and a pattern of cool and
unsettled weather.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1121 AM MDT Tue Apr 9 2024

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals.

Instability showers over the western mountains this afternoon, with
KJAC the most likely to see a brief MVFR or low-end VFR shower.
HiRes solutions do not give much confidence in a prevailing or TEMPO
group, and feel VCSH might be the preferred option. Weak
shortwave crosses the region between 00Z-09Z/Wednesday, leading
to a better chance of MVFR at KJAC between 01Z-06Z. KPNA could
see flurries or brief MVFR a few hours later. This shortwave
clears the region by 12Z/Wednesday with VFR to follow. Gusty
westerly wind 15-25kts fades at KBPI and KPNA around
01Z/Wednesday, while KRKS keeps 14-22kt winds all night. KJAC
sees a light northerly surface wind for Wednesday morning
following passage of the shortwave. Mountain tops frequently
obscured until 10Z/Wednesday.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

Conditions remain VFR at all terminals through at least
06Z/Wednesday. Afternoon instability showers develop over the
mountains with potential brief impacts most likely to occur at
KCOD. A quick-moving clipper-like shortwave crosses the region
between 03Z- 15Z/Wednesday, leading to the best chance of
showers and potentially MVFR conditions at KWRL and then KCPR.
Temperatures may allow for -SHRA at the onset at KWRL, but
believe it would be more likely to see -SHSN. Cyclonic flow
aloft favors a shot of light snow at KCPR between
10Z-14Z/Wednesday, and MVFR, or even IFR, would not be a
surprise. Have at least trended to low-end VFR with this
issuance. Other terminals to remain VFR throughout. Gusty
westerly wind fades around 00Z-02Z/Wednesday at KCOD and KCPR.
Mountain tops frequently obscured 03Z-15Z/Wednesday.

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...
None.

&&

$$

DISCUSSION...Hattings
AVIATION...CNJ