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000
FXUS65 KRIW 180012
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
612 PM MDT Wed Apr 17 2024

.KEY MESSAGES...

- Temperatures have been several degrees cooler than expected
  today, producing higher than expected snowfall amounts across
  portions of the region.

- Snow showers will persist through this evening, with rates
  significantly decreasing after sunset. Additional
  accumulations will generally be light, with highest totals
  across the Bighorns and Absaroka mountains.

- Behind the shortwave, the cooler weather sticks around through
  the early part of the weekend, but weather will remain mostly
  dry.

- High pressure looks to return late in the weekend and continue
  through much of next week.

&&

.DISCUSSION...
Issued at 211 PM MDT Wed Apr 17 2024

Temperatures have been in the low 30s across most locations today,
which is 5 to 10 degrees below the previous forecasts (and most
model guidance). As a result, precipitation has generally been in
the form of snow, rather than rain, and it has accumulated more than
expected across lower elevations including near Buffalo and Cody.
SPS`s remain in effect for the aforementioned areas, and opted
against any additional highlights due to minimal road/travel impacts
and additional accumulations will be minimal (generally less than an
inch) through the rest of the afternoon and evening. As of 2 PM,
snow continues to fall at a steady rate across the western mountains
and Yellowstone Park, as well as the Bighorns, so current Advisories
and Warnings remain in place.

As the shortwave continues to exit this evening, snowfall rates will
significantly drop off after sunset. Locations that may see snow
linger through much of the night include the Wind River Basin and
Natrona county due to northerly (upslope) flow. Snow ends everywhere
towards sunrise Thursday morning, and Thursday will see mostly sunny
skies prevail across the CWA. The long wave trough will remain in
place through the early part of the weekend. Weak, orographic and
diurnally driven snow showers may remain possible across the western
and northern mountains, but otherwise, it will remain dry through
Saturday. With the trough in place, temperatures will remain 10 to
15 degrees below normal, however.

The trough produces one last hoorah over the weekend, with a weak
shortwave. Impacts look minimal, and likely will be reduced to some
snow showers across the western mountains. By Sunday, a ridge begins
to build into the region. Temperatures will start on a more notable
warming trend, and relatively quiet weather looks to prevail through
much of next week as a result of the high pressure. Models do hint
at some shortwaves in the ridge, but are not agreeing on timing or
intensity. At this time, any shortwaves look to be weak, with little
confidence in any widespread precipitation chances through the next
7 to 10 days.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 612 PM MDT Wed Apr 17 2024

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

Instability showers have generated IFR/MVFR conditions at KJAC,
conditions that are likely to persist until around 02Z. Light
snow ends at KJAC between 02Z-04Z and conditions trend to VFR
around 04Z. To the south, VFR conditions and gusty west to
northwest wind 15-30kts prevail through 06Z before speeds
diminish in earnest. A surface cold front backs into KRKS around
06Z generating east-northeast wind at 12kts the remainder of
the night. Westerly wind does return to the southwest terminals
Thursday afternoon, but speeds will be much less than those of
Wednesday. All terminals to be VFR after 06Z, but mountain tops
remain occasionally obscured until 12Z.

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

Jet energy streaming east across the region has generated
banded areas of light snow east of the Continental Divide
Wednesday afternoon. High-resolution models continue to depict a
secondary surge this evening to favor a period of IFR/MVFR from
KRIW/KLND to KCPR, generally between 01Z-04Z. MVFR to linger
much of the night at KCPR and KLND. KWRL could see a brief
period of MVFR until around 02Z, otherwise VFR looks to prevail
there and at KCOD during the period. All terminals to be VFR by
15Z. Gusty northerly wind fades between 04Z-08Z. Mountain tops
frequently obscured until 12Z.

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 until 6 AM MDT Thursday for WYZ001-002-
012.

Winter Storm Warning until 6 AM MDT Thursday for WYZ008-009.

&&

$$

DISCUSSION...Hensley
AVIATION...CNJ