Green River, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

731
FXUS65 KRIW 080744
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
144 AM MDT Tue Apr 8 2025

.KEY MESSAGES...

- Rain and/or snow chances (30-60%) exist across western and
  northern Wyoming today, with precipitation tapering off and
  generally ending overnight.

- Elevated fire weather conditions are possible Tuesday and
  Wednesday with windy and dry condiditons.

- Strong winds are expected Tuesday and especially Wednesday
  afternoon, with gusts generally 30 to 35 mph across most
  locations. Gusts locally up to 40 to 50+ mph are expected in
  wind prone areas and across higher mountain peaks.

- Warm, near record high temperatures forecast Thursday through
  Saturday.

&&

.DISCUSSION...
Issued at 135 AM MDT Tue Apr 8 2025

High pressure, which has brought us seasonally warm and dry weather
for the last few days will be squashed slightly today and tomorrow
(Wednesday) as a shortwave trough passes to our north. Showers are
beginning to make their way into far western WY as of this writing
(0100L). Snow levels are expected to remain around 7500 to 7700
ft through the day, and thus, precipitation will generally be
rain across the valleys with snow in the mountains. Models have
continued to trend drier with this shortwave, and thus
precipitation amounts have decreased compared to the previous
forecast. Generally less than 0.5" of liquid equivalent
precipitation is expected, with highest amounts across
Yellowstone NP and the Teton Mountains. With snow levels
generally around 10:1, this equates to 2 to 4 inches of snow
across YNP and the Tetons, with locally higher amounts up to 6
inches across higher favored terrain such as the Pitchstone
Plateau in SW YNP. Rain and mountain snow showers will taper off
and end overnight. There is a 10 to 20% chance of lingering
showers (and thunderstorms) across northern WY through the day
Wednesday, but chances are low enough that most mentions of
precip have been removed from deterministic forecast products.

For today, however, showers and thunderstorms are possible
(20 to 30%) across northern WY. Precipitation will generally be
showery (i.e., convective) in nature, thanks to some weak
frontogenesis along the main cold front and instability
developing during the afternoon (SB CAPE ~200 to 500J/kg). This
instability, combined with orographics will help to prolong the
rain/snow showers across YNP and along the Absarokas and Tetons
through much of the afternoon. It will also help to bring some
convective rain showers, and yes, some isolated thunderstorms
that develop off the Absarokas, across the Bighorn Basin this
afternoon (10 to 15% chance). Any showers and thunderstorms
will be weak and short- lived given limited instability. The
primary threat will be some gusty winds (up to 40 mph) and/or
abrupt wind shifts with potential outflow boundaries, but again,
threat is very minimal.

With the shortwave through, the gradient will tighten today, and
even more so on Wednesday, resulting in gusty west to southwest
winds across much of the region. Gusts 30 to 40 mph will be common
along the Wind Corridor and Wind River and Absaroka eastern slopes
today. Those gusts increase to 35 to 45 mph Wednesday afternoon as
the parent low slides across the Dakotas. South Pass is the location
with greatest likelihood (40% chance) for gusts 50+ mph both days,
but prolonged gusts over 60 mph are not expected anywhere (less than
5% chance), and thus no High Wind highlights are planned. The gusty
winds will lead to an elevated fire weather concern both today and
Wednesday, however, fuels are in green up and RHs will be generally
not near critical thresholds due to increased cloud cover and cooler
temps behind the cold front. Wednesday will see slightly drier RHs,
but still not reaching critical thresholds.

After the shortwave exits Wednesday afternoon, high pressure quickly
returns for Thursday. Temperatures will rebound to well above normal
values. By Friday afternoon, models prog 700mb temps of +8 to
+10C across much of southwest and central WY. Several daily
high temperature records are expected to be at least threatened,
if not broken, with high temps likely (80% chance) around 80F
across many basin locations east of the Divide. West of the
Divide, especially across Sweetwater County, temperatures into
the mid to upper 70s are expected, and those locations to be
most likely to break records on Friday.

With the near-record warm temperatures, there is expected to be some
snowmelt Friday and Saturday. To note though, Mountain
locations are expected to see lows drop below freezing at night,
and the extreme warmth will not last more than 1-2 days, thus
impacts should be minimal and no flooding is expected. That
being said, be aware that rivers will likely be running a bit
higher than normal Friday and especially Saturday.

The next shortwave moves in Saturday, with temperatures returning to
more seasonal values by Sunday. With this shortwave, there are also
increasing precipitation chances across northern WY Saturday
afternoon through Sunday. This does not look to be a particularly
wet system, but there are a lot of details that still need to be
worked out in the coming days, as there is still quite a bit of
model uncertainty.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 949 PM MDT Mon Apr 7 2025

VFR conditions are expected across all terminals east of the Divide.
KJAC, KBPI, and KPNA may see a few showers move over or nearby
terminals for the start of the period. KJAC has the best chance of
the three terminals to see a brief shower (30-60%). For that reason
a TEMPO group has been added through 10Z Tuesday for the possibility
of lowered ceilings and vis due to light showers. KBPI/KPNA have a
much lower chance (10-30%) of seeing a stray shower move through the
area and due to the low chance, no precipitation related groups have
been added to these terminals. The remaining terminals will likely
see VFR conditions prevail through the TAF period with their main
concern being increasing winds Tuesday afternoon. Winds pick up by
the late morning into the afternoon on Tuesday with all terminals
seeing periodic gusts of 20 to 30 knots. Stronger gusts exceeding 30
knots will be possible at KRIW, KCPR, KRKS, and KCOD. Winds decrease
gradually through the evening becoming mostly light by the end of
the period. One thing to note about Tuesday afternoon will be the
chance for showers and thunderstorms across northern WY. KCOD may
see a brief shower and due to that VCSH has been added through the
afternoon. The remaining terminals will likely see no precipitation
as a result of this convection. Mountains will see periods of
obscuration especially across the more northernly positioned
ranges.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence
forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Hensley
AVIATION...Dziewaltowski