National Weather Service Local Forecast for Star Valley Ranch
Updated: Thu May 08  9:28 pm MT

Tonight... Clear, with a low around 40. Northeast wind around 5
mph becoming light and variable  after midnight. 

Friday... Sunny, with a high near 70. Calm wind becoming west
northwest 5 to 7 mph in the afternoon. 

Friday Night... Clear, with a low around 42. West northwest
wind around 6 mph becoming calm. 

Saturday... Sunny, with a high near 76. East southeast wind 5
to 8 mph becoming southwest in the afternoon. 

Saturday Night... Partly cloudy, with a low around 50.
Southwest wind 6 to 8 mph becoming southeast after midnight. 

Sunday... A slight chance of showers, then a chance of showers
and thunderstorms after noon.  Partly sunny, with a high near 72.
Breezy, with a south southwest wind 8 to 15 mph, with gusts as high as
23 mph.  Chance of precipitation is 50%.

Sunday Night... Showers likely, mainly before midnight.  Mostly
cloudy, with a low around 47. South southeast wind 9 to 11 mph, with
gusts as high as 20 mph.  Chance of precipitation is 60%.

Monday... A chance of showers, with thunderstorms also possible
after noon.  Mostly sunny, with a high near 66. Chance of
precipitation is 40%.

Monday Night... A 30 percent chance of showers, mainly before
midnight.  Partly cloudy, with a low around 41.

Tuesday... A chance of showers, then showers likely and
possibly a thunderstorm after noon.  Partly sunny, with a high near
58. Chance of precipitation is 60%.

Tuesday Night... Showers likely.  Mostly cloudy, with a low
around 37.

Wednesday... Rain and snow showers likely. Some thunder is also
possible.  Mostly cloudy, with a high near 48.

Wednesday Night... A chance of rain and snow showers.  Mostly
cloudy, with a low around 35.

Thursday... A chance of rain and snow showers. Some thunder is
also possible.  Partly sunny, with a high near 53.

	

	
775 
FXUS65 KRIW 090352
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
952 PM MDT Thu May 8 2025

.KEY MESSAGES...

- Isolated showers and thunderstorms return to mainly northern
  Wyoming Friday afternoon. The best chance (15-25 percent)
  occurs over and east of the Absaroka and Bighorn Mountains.

- Near record breaking temperatures are forecast for the
  weekend. Highs reach 70s west of the Continental Divide and 
  the lower to mid 80s east of the Divide.

- The arrival of a weather system early next week will cool
  temperatures between Monday and Wednesday. Precipitation
  chances increase with this system, especially Tuesday 
  afternoon through Wednesday.

&&

.UPDATE...
Issued at 105 PM MDT Thu May 8 2025

Partly to mostly sunny skies prevail across the state today as 
a stretch of above normal temperatures and mainly dry conditions
develop. A few isolated showers cannot be ruled out across the 
higher elevations of northern WY this afternoon/evening. The 
main concern will be outflow winds produced by any storms that 
do develop. High temperatures today as mentioned earlier will 
begin to climb to above normal values. Highs east of the Divide 
will range from the low to upper 70s with locations west of the 
Divide seeing highs in the mid to upper 60s.

Ridging builds in for the end of the week through the weekend. This 
will usher in well above normal temperatures with highs in the low 
70s to low 80s Friday. Friday afternoon and evening will see another 
chance for isolated showers mainly across portions of Natrona and 
Johnson Counties. Warming continues for the weekend with locations 
east of the Divide seeing highs in the low to upper 80s and mid to 
upper 70s west of the Divide. The warmest temperatures are expected 
to be across the Bighorn Basin where highs may near or even exceed 
90 degrees. Looking at climate records there is the potential for 
some locations to see near record high temperatures over the 
weekend. The well above normal temperatures may create some issues 
regarding snowmelt of the remaining high elevation snow pack. 
As of Thursday the threat looks minor with the main concern 
being increased small tributary flows with larger rivers likely 
not being of much concern.

Sunday will see the ridging gradually pushed eastward with 
a weak disturbance starting to move into the region. This disturbance 
will lead to the chance for showers and thunderstorms to develop 
across the state during the afternoon and evening on Sunday. Due to 
the lack of moisture most of these showers will face a rather dry 
atmosphere leading to mainly virga showers. The other concern due to 
this dryness will be strong gusty outflow winds with any developing 
storms. Temperatures being in the 70s to 80s with dew points in
the 30s would likely translate to outflow winds of 40 to 50 
mph. Monday will see warm temperatures linger with breezy winds 
developing ahead of the next potential weather maker. Currently 
this disturbance looks to bring widespread chances for 
precipitation by the middle of next week. However, being nearly 
a week out there is still a lot of uncertainty especially 
regarding the timing and track of this disturbance which would 
alter impacts for the region.

&&

.DISCUSSION...
Issued at 109 AM MDT Thu May 8 2025

The latest return of spring continues to build across western WY
the next few days as H5 ridging builds across the Intermountain
West. H7 temperatures ranging 5 to 10C will translate to sfc
temps in the 70s across the lower elevations today. Since the
ridge hasn't yet build into Wyoming, a weak shortwave will sweep
generally across northwest WY during the afternoon hours. This
wave will tap some of the daytime heating, allowing some shower
activity to build along the highest mountain ranges during peak
heating. Most of these will be smaller in size, so any
accumulations will be minor. 

Ridging builds closer to western WY on Friday, but temperatures
will remain similar to Thursday mainly in the 70s. Similar to
today, a weak wave will sweep around the edge of the ridge
during the afternoon. With the ridge closer to western WY, it
will suppress convection for most areas during peak heating, but
the Bighorns and areas downwind across Johnson and Natrona
Counties will be far enough from the ridge to allow some 
showers to again bubble up during peak heating. 

Over the weekend, the ridge finally centers on western WY,
deflecting any impulses off to the north. H7 temperatures jump
to 10 to 15C, so temperatures in the upper 70s and lower 80s
are likely. Some areas of the Bighorn Basin and Johnson County
may jump into the upper 80s, with a remote 90 degree reading not
out of the question. This ridging and warm temperatures aloft
will increase the threat for snowmelt of the remaining higher
elevation snowpack.

Early next week focuses on the next large-scale trough coming
ashore along the PacNW. Latest model runs showing some improved
tap of moisture off the Pacific into western WY. Models are
still differing on the depth and speed of this next trough, but
are starting to increase some of the rain chances out west due
to the improved moisture availability.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 951 PM MDT Thu May 8 2025

VFR conditions prevail through the period. Mid-to-high level clouds 
clear through the night, generally from west to east. High pressure 
keeps a mostly clear sky through Friday. There is about a 20 percent 
chance of a rain shower or storm around KCPR 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.

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...Straub
AVIATION...Wittmann

	

	
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