000
FXUS65 KRIW 180505
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1105 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 /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1104 PM MDT Wed Apr 17 2024

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

In general, VFR conditions prevail through the forecast period. Back
door cold front on the KRKS doorstep will bring east-northeast 10-
15kt wind and a 30-50 percent chance of MVFR ceilings between 10Z-
16Z. Westerly wind does return to the southwest terminals mid-
afternoon Thursday, with speeds 10-15kts. Mountain tops remain
occasionally obscured until 16Z.

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

A combination of shortwave energy and jet support has generated
light snow across the central basins from KRIW/KLND to KCPR
Wednesday evening. The best chance for MVFR conditions at these
terminals lasts until 08Z, but flurries, low-end VFR, and
intermittent MVFR could persist until around 12Z-15Z. KCPR and KLND
would see these pesky conditions linger longest. All terminals to be
VFR by 15Z. Instability showers form over the mountains Thursday
afternoon with mid-cloud decks for many areas through the remainder
of the period. KCOD would have the best opportunity to see a brief
shower, but confidence is low. Mountain tops occasionally obscured.

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

&&

$$

DISCUSSION...Hensley
AVIATION...Jones