146
FXUS65 KRIW 291042
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
442 AM MDT Mon Apr 29 2024

.KEY MESSAGES...

- Another afternoon of isolated showers and thunderstorms,
  spreading east with a cold front this evening. Gusty wind
  ahead of this front.

- Light accumulating mountain snow is expected through this
  evening. Snow levels will approach the floors of western
  valleys, but any accumulation will be minor.

- Elevated fire weather conditions Tuesday for much of central and
  southern Wyoming.

- Unsettled conditions continue midweek, with chances for light
  snow for most of the area Wednesday night.

&&

.DISCUSSION...
Issued at 440 AM MDT Mon Apr 29 2024

A few light showers are lingering early this morning in the wake of
yesterday`s wave. These will mostly die off as we near sunrise,
leaving a dry rest of the morning. However, the next shortwave
within the broadly cyclonic flow is quickly approaching. With the
addition of some Pacific moisture advection, this wave will kick off
another round of isolated convection this afternoon across western
Wyoming. The bulk of this activity will stay west of the Divide
through the afternoon, before increasing in coverage to the east
this evening as a cold front pushes through. Ahead of this front,
wind will increase as a surface low develops across northeastern
Wyoming. This will make for a gusty afternoon for the majority of
the area, but especially from southwestern Wyoming through Natrona
County.

Also to note will be a few inches of snow across the mountains
through this evening. As the cold front passes, snow levels will
drop, possibly down to the floor of Jackson Hole after sunset. This
valley could see a brief period of light snow, but precipitation
will be waning as temperatures drop. Regardless, the latest run of
the HREF suggests a 30 to 50 percent chance of light accumulation
(0.1") for the lower elevations of Jackson Hole.

While a few snow showers may linger across the mountains,
precipitation elsewhere will come to an end overnight as the front
moves from west to east.

On Tuesday a flattened, diffuse trough will be situated to the north
of Wyoming. Flow will be more westerly across the area. Convection
chances will return, but will be more restricted to northern
Wyoming. Most of the area will be cooler and dry, though again with
a gusty wind through the afternoon. With drier air aloft and a
mixing wind, humidity values are likely to fall into the teens
across most of the lower elevations leading to elevated fire weather
conditions.

On Wednesday, the northern trough axis is progged to rotate towards
Wyoming. This will return wider precipitation coverage to the area,
again especially across northern and western Wyoming. Cooler
temperatures are set to arrive Wednesday night, likely bringing snow
levels down to or near basin floors by Thursday morning. Models are
coming more into agreement on this, showing 700mb temperatures down
to -8C. However, this system does not look to have much moisture to
work with, and any accumulations currently appear light.

Uncertainty creeps back up further out. Guidance currently favors a
warmer end to the week, though with lingering precipitation chances
as unsettled conditions continue.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1049 PM MDT Sun Apr 28 2024

VFR conditions prevail overnight, with relatively light winds. Winds
begin to increase Monday morning, with gusts to around 30 knots by
the afternoon for many sites. There is a possibility for higher
gusts for KBPI, KCPR, KPNA, and KRKS, possibly to 35-40 knots; will
have to reevaluate wind potential with newer model runs.

Precipitation begins over western Wyoming around 18Z/Mon. As a weak
cold front passes through, rain chances spread eastward through the
day, reaching the Continental Divide roughly around 00Z/Tues. All
sites have a chance of rain through the TAF period, but lower
confidence for locations east of the Divide, so have left mention
out for most locations for now.

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...Myers
AVIATION...Wittmann