535
FXUS65 KRIW 100441
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1041 PM MDT Thu May 9 2024

.KEY MESSAGES...

- Rain chances today and tomorrow (20% to 60%), mainly east of
  the Continental Divide and over Sweetwater County. Some
  thunder is possible.

- Warmer this weekend, with less rain chances.

&&

.DISCUSSION...
Issued at 1111 AM MDT Thu May 9 2024

That low pressure system that has brought gusty winds, rain, snow,
and cloudy days has finally weakened and is moving eastward today.
As its influence weakens over Wyoming, precipitation chances will be
on the downward trend. Today, some lingering showers from overnight
and this morning continue to move through the area. Showers are also
favored to develop this afternoon in northeast flow. Rain chances of
20% to 60% occur through the day east of the Continental Divide. For
west locations, chances (30% to 50%) will generally be confined to
the higher terrain, with a few showers moving off the mountains to
the nearby lower elevations. A rumble of thunder is possible today.

A Winter Storm Warning continues for the eastern Wind River
Mountains through this evening as favored flow continues. Snow rates
should decrease through the afternoon. Snow showers this afternoon
may bring localized moderate snow rates, while other locations
receive lesser amounts. A couple inches are possible late this
evening into the early overnight hours, but the main impacts should
be ending through this afternoon.

A cutoff low develops to our southwest (Utah area) today as well.
This should keep the northeast-to-east flow going tonight and into
tomorrow. The main impacts of this low remain to our south, but some
moisture continues rain chances (15%-30%) overnight for east of the
Divide locations, mainly for the mountains, and near Lander and
Casper where favored upslope occurs. Fog is also possible (30%)
overnight into Friday morning, especially for locations with recent
rainfall, such as the Wind River Basin and Johnson/Natrona Counties.

Rain chances will be less during the day Friday, generally 15% to
25% chances, mainly across Fremont, Natrona, and Sweetwater
Counties. A rumble of thunder is also possible with these shower
chances Friday afternoon. After sunset Friday, rain chances quickly
drop off across the area, with less than 10% chances across the
entire area.

Ridging sets up for this weekend. Peak heating during the day
Saturday, in combination with the cut off low moving eastward, could
bring some afternoon showers/thunderstorms for the southern half of
the area, mainly Sweetwater County. These decrease after sunset.
Temperatures Saturday peak near, to a little above, normal. Highs in
the 60s to low 70s are expected. Sunday is similar, with slightly
warmer temperatures and afternoon showers possible.

A slightly bigger weather system is projected by models for Monday
into Tuesday. Overall, it does not appear very impactful at this
time, but could bring some gusty winds and rain chances. Uncertainty
towards the end of next week, with some models showing a stronger
ridge building in.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1039 PM MDT Thu May 9 2024

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

Prevailing VFR conditions through the TAF period as the persistent
weather system begins to exit the area. Isolated showers are
possible at KRKS through Friday afternoon, but too low of a chance
(20%) for a prevailing -SHRA group. Wind will remain strong at KRKS
through Friday afternoon from the northeast, with gusts to 30 knots
by 12Z. At KJAC the predominant wind direction will be northerly
right around 10 knots through the TAF period. Scattered mountain
obscuration will occur.

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

The persistent weather system continues to influence the weather
conditions through Friday afternoon, but it will slowly exit the
area leading to lesser impacts on Friday. An area of -SHRA is
approaching KLND and should impact the terminal until 08Z, with a
lowering in clouds to MVFR once it passes. Isolated -SHRA remain
possible (30%) at KLND through Friday morning. Improvement to VFR
will occur by Friday afternoon as CIGS rise. Isolated -SHRA remain
in the vicinity of KCPR tonight and become more scattered by 10Z/Fri
as CIGS drop to IFR until 15Z/Fri. By that time improvement to VFR
will occur. Other terminals will remain mostly dry and VFR, although
an isolated -SHRA is possible (20%) through Friday afternoon. Wind
will become light tonight, mainly from the north/northeast. Mountain
obscuration will persist along the eastern slopes of mountain ranges
as easterly upslope flow persists through Friday afternoon.

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...Wittmann
AVIATION...Rowe