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000
FXUS65 KRIW 202322
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
522 PM MDT Sat Apr 20 2024

.KEY MESSAGES...

- Dry weather continues through Sunday morning.

- Much warmer Sunday with elevated fire weather possible in the
  afternoon. Elevated fire weather also possible in southern
  Wyoming on Monday.

- A cooler and wetter pattern moves in for late next week, but
  confidence in the details remains very low.

&&

.DISCUSSION...
Issued at 127 PM MDT Sat Apr 20 2024

Well, the saga of the self destructive sunshine has ended with
ridging moving over the area. It has brought a nice start to
the weekend for most of the area, although it feels more like a
March than an April day with temperatures averaging 10 degrees
below normal. The strong late April sun is helping make it feel
warmer though. This tranquil weather will continue through the
first part of tomorrow, so we won`t spend anymore time of this
period.

Things turn a bit more active tomorrow as a weak shortwave and
Pacific cold front move across the area. This system has little
moisture to work with though, so shower coverage will be sparse.
There is no more than a 1 in 3 chance for the lower elevations.
And even in the mountains, amounts will be light, with less
than 1 out of 4 chance of an inch or snow. The main story looks
to be wind and possible elevated fire weather. With the
tightening pressure gradient, the favored southwest flow areas
will see breezy to windy conditions develop. With relative
humidity falling to around 20 percent, elevated fire weather
will be possible in the southwesterly flow areas, mainly from
Rock Springs to Casper. It will also be a much warmer day, with
highs generally 15 to 20 degrees warmer than today.

Dry conditions will return for Monday, but the pattern will be
more zonal. This means fast flow, especially across southern
Wyoming, where a windy afternoon will be possible, with a 1 out
of 2 chance of wind gusts past 40 mph across Sweetwater County.
With humidity even lower, elevated fire weather will be possible
across this area on this day as well. In areas East of the
Divide, somewhat cooler temperatures and higher humidity behind
the front should ease fire conditions somewhat.

The forecast is more in flux starting on Tuesday. A few showers
are possible in far southern Wyoming with a weak shortwave
passing by, but for the most part things look largely quiet with
near normal temperatures. Temperatures warm again on Wednesday
as flow turns southerly ahead of another advancing wave. This
may bring a better chance of showers and maybe thunderstorms to
much of the area. This system, like the other ones, does not
have a lot of moisture to work with so the chance of one in any
location is less than 1 in 3 for the most part.

Uncertainty really ramps up for the end of the week. Things
continue to be dependent on two lows, one passing to the north
and the other to our south, and how they interact. Model
guidance, of the deterministic and ensemble varieties, continues
to have poor run to run continuity. Timing of the systems varies
by as much of 2 days and don`t get my started on placement of
precipitation. So, to sum things up, confidence in a return to a
cooler and wetter pattern is high, greater than a 3 in 4
chance. However, we have little confidence in the details of the
timing and placement of precipitation for the end of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 521 PM MDT Sat Apr 20 2024

VFR conditions, dry and light (11 kt or less) winds will be in
place through the TAF period. Wind gusts up to 20 kt will be
subsiding at KBPI/KPNA and KRKS through 02Z. Skies will mostly clear
across the forecast area by 04Z. High clouds will return from the
west late tonight into Sunday morning. Wind gusts up to 25 kt will
return again Sunday afternoon, as a weak system passes over the area
from the north.

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...LaVoie