National Weather Service Local Forecast for Star Valley Ranch
Updated: Sun Dec 22  8:59 am MT

Today... Scattered snow showers before 3pm, then scattered rain
and snow showers.  Areas of fog.  Otherwise, cloudy, with a high near
34. East southeast wind 3 to 6 mph.  Chance of precipitation is 50%.
Total daytime snow accumulation of less than a half inch possible. 

Tonight... A chance of rain and snow before 7pm, then snow
likely.  Areas of fog.  Otherwise, cloudy, with a low around 25. South
southeast wind 3 to 5 mph.  Chance of precipitation is 70%. New snow
accumulation of less than a half inch possible. 

Monday... Rain and snow, mainly before 5pm.  Areas of fog
before 11am. High near 35. Southwest wind 5 to 8 mph.  Chance of
precipitation is 100%. New snow accumulation of less than a half inch
possible. 

Monday Night... A 30 percent chance of snow, mainly before 8pm.
 Mostly cloudy, with a low around 21. West southwest wind 5 to 7 mph
becoming light and variable. 

Tuesday... A slight chance of snow before 2pm, then rain
likely, possibly mixed with snow.  Mostly cloudy, with a high near 39.
East southeast wind 3 to 6 mph.  Chance of precipitation is 60%. New
snow accumulation of less than a half inch possible. 

Tuesday Night... Rain and snow likely before 7pm, then snow. 
Low around 28. East southeast wind 5 to 8 mph becoming west after
midnight.  Chance of precipitation is 80%.

Christmas Day... Snow likely, mainly before 11am.  Cloudy, with
a high near 33. West wind 3 to 5 mph.  Chance of precipitation is 70%.

Wednesday Night... Mostly cloudy, with a low around 18.

Thursday... Snow, mainly after 11am.  High near 31. Chance of
precipitation is 80%.

Thursday Night... Snow.  Low around 24. Chance of precipitation
is 80%.

Friday... Snow.  Cloudy, with a high near 32.

Friday Night... Snow likely.  Cloudy, with a low around 26.

Saturday... Snow.  Cloudy, with a high near 35.

	

	
334 
FXUS65 KRIW 221118
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
418 AM MST Sun Dec 22 2024

.KEY MESSAGES...

- Increasing snow chances for the western mountains now through
  Monday. Winter Weather Advisory in Effect for the Tetons.

- Next weather system moves to the south Christmas Day, but may
  bring brief light snow to western Wyoming. 

- Areas of Wyoming east of the Divide remain dry and mild for
  the latter half of December.

&&

.DISCUSSION...
Issued at 201 AM MST Sun Dec 22 2024

Light snow has begun to fall across the western mountain this
morning, but precip has been light and minimal so far. The main
portion of the first shortwave trough is already passing by to
the north across Montana, so only light snow continues for the
western mountains today, mainly fueled by orographic lift. The
next trailing trough is moving ashore along the PacNW Coast, and
should be bringing increased moisture by this evening to western
WY. While moisture is still only modest, enough mountain lift
will be available to bring modest snow amounts again to the
western mountains. This snow will continue into the day Monday
as the trough moves through before decreasing Monday evening.
Snow totals for the Tetons remain steady at 8 to 12 inches, with
6 to 8 inches for the Salts and Wyomings and the greater Gros 
Ventres. Winter Weather Advisories remain in effect through 
Monday evening for the Tetons. 

Unfortunately for a pattern like this, getting any moisture over
the mountain ranges into the central WY plains will be unlikely,
and will also be counteracted by westerly downsloping bringing 
warmer temperatures. The system will help bring down temps 
somewhat, but highs still reach the 40s, with some localized 
warmer temperatures just off mountain ranges.

Expect a brief lull between systems on Tuesday, just enough to
get the the jolly fellow and his herd of flying Rangifer 
tarandus into the state to make his yearly rounds. The next 
shortwave sweep by to the south pre-dawn Christmas morning, but
will be just close enough to bring another round of light snow 
to the western mountains.

Still not much to speak of beyond Christmas weather-wise, with
models keeping fast zonal flow going through the rest of the
week. This would keep light snow continuing along the western
mountains, but only light amounts, and keeping temperatures 
mild east of the Divide.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 415 AM MST Sun Dec 22 2024

Weak disturbances aloft are beginning to move across the 
Intermountain west and influence the weather and flight conditions 
at multiple terminals through the TAF period. At KJAC, southwesterly 
winds with gusts less than 20 kts are expected over the next few 
hours with light snow all day. Ceilings are forecast to lower around 
18Z with impacts beginning around 21Z. Expect IFR visibilities 
through at least 04Z and MVFR ceilings through Monday morning; 
however, brief periods of IFR visibilities after 04Z cannot be ruled 
out.

At KBPI and KPNA, confidence is high in fog development after 03Z. 
There is an 80% chance of MVFR fog at KPNA and an 80% chance in IFR 
fog at KBPI. Confidence in IFR fog at KPNA is much lower (around 
30%) so kept MVFR fog at this time. Fog at these terminals will 
persist through the rest of the TAF period. Expect windy conditions 
at KCPR, KCOD, and KRKS today with gusts around 25 kts beginning 
between 18-19Z at KCOD and KRKS and diminishing shortly after 
sunset. Winds at KRIW are forecast to increase after sunset to above 
10 kts. Otherwise, at all other terminals, winds will generally be 
less than 10 kts.

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 7 PM MST Monday for WYZ012.

&&

$$

DISCUSSION...Straub
AVIATION...Gerhardt

	

	
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