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Latest ZFP from WFO RIW
National Weather Service Local Forecast for Star Valley Ranch
Updated: 17 Oct 03:10 am MDT

Overnight... Mostly clear, with a low around 33. Light and
variable wind becoming east southeast around 5 mph. 

Sunday... Sunny, with a high near 59. East southeast wind 5 to
9 mph becoming south southwest in the afternoon. 

Sunday Night... A slight chance of rain and snow after 5am. 
Partly cloudy, with a low around 32. Southeast wind 5 to 8 mph. 
Chance of precipitation is 20%.

Monday... A slight chance of rain and snow before 9am, then
rain. Some thunder is also possible.  High near 52. Southeast wind 5
to 7 mph becoming west in the afternoon.  Chance of precipitation is
80%. Little or no snow accumulation expected. 

Monday Night... Rain before 1am, then rain and snow. Some
thunder is also possible.  Low around 28. West wind 5 to 7 mph. 
Chance of precipitation is 80%. New snow accumulation of less than one
inch possible. 

Tuesday... A chance of snow before 7am, then a chance of rain
and snow.  Mostly cloudy, with a high near 35. West wind around 6 mph.
 Chance of precipitation is 40%.

Tuesday Night... Mostly cloudy, with a low around 26. West
northwest wind around 6 mph becoming east southeast after midnight. 

Wednesday... Mostly sunny, with a high near 50.

Wednesday Night... Mostly cloudy, with a low around 27.

Thursday... Mostly sunny, with a high near 53.

Thursday Night... Partly cloudy, with a low around 29.

Friday... Partly sunny, with a high near 56.

Friday Night... A slight chance of showers.  Mostly cloudy,
with a low around 33.

Saturday... A slight chance of showers.  Partly sunny, with a
high near 51.


Latest AFD from WFO RIW
FXUS65 KRIW 170533

Area Forecast Discussion
National Weather Service Riverton WY
1133 PM MDT Sat Oct 16 2021

.SHORT TERM...This evening through Sunday night
Issued at 200 PM MDT Sat Oct 16 2021

Upper-level ridging has moved into the area, but the ridge axis 
is still to the west of the area. As the weekend progresses, that 
ridge axis will shift eastward over the area continuing to keep 
the forecast warmer and drier. Today will feature more seasonal 
temperatures, with clear skies and staying dry but with the clear 
skies today and overnight opted for patchy fog Sunday morning. 
Patchy fog is possible Sunday morning across streams, rivers and 
reservoirs. Fog lifts out by midday, while still remaining warmer
and drier. As the ridge shifts eastward during the day Sunday, 
southwesterly flow ahead of the next trough will advect warmer 
temperatures and moisture but a wind maxima is progged to move 
over the area Sunday afternoon and into early Monday morning. 
Those winds are forecast to mix down across the Wind Corridor with
isolated gusts to 40 mph Sunday afternoon. 

Models are continuing to suggest another potent system bringing wind 
and widespread rain and snow to the area Monday. Not going to dive 
into the details of that system, as the bulk of the storm is in 
the long-term; however, impacts to the western mountains will 
slowly increase as early Monday morning.

.LONG TERM...Monday through Saturday
Issued at 200 PM MDT Sat Oct 16 2021

A storm system will continue to make its way over northern portions 
of the Great Basin Monday morning. This system will begin to cut off 
from the main flow of the jet stream during the day Monday. The 
first round of precipitation will reach western portions during the 
afternoon, under an area of deformation. Model consensus has the low 
center moving along the WY/CO border Monday night, reaching the 
Cheyenne area between 12Z and 18Z Tuesday. Precipitation will spread 
across the rest of the area Monday night and end from west to east 
through the day Tuesday. This system is not as cold as the one last 
week, as it is Pacific in origin. Snow levels will range between 
6500 and 7500 ft for much of the forecast area, with the coldest air 
occurring near the center of the low. Thus, the best chances for 
snow in the lower elevations will be across southern portions 
(Sweetwater, Sublette and southern Lincoln counties. Snowfall 
amounts of 3 to 6 inches is forecast in the mountains. There is a 
signal for moderate to heavy rain (or a rain/snow mix) to fall over 
portions of southern Johnson/northern Natrona counties Tuesday, due 
to flow on the northeast side of the low. Gusty north to northwest 
winds will develop over areas east of the Divide and southern 
portions late Tuesday morning into the afternoon, as the low begins 
to exit over the High Plains. A transitory ridge builds over the 
region in the wake of this system Wednesday, with ridging remaining 
in place until Saturday.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1128 PM MDT Sat Oct 16 2021

VFR conditions through the TAF period. Breezy southwest winds
Sunday afternoon from the eastern Sweetwater County northeast 
into southern Johnson County. These winds will primarily impact 
the KCPR terminal, and diminish quickly around 00Z Monday.
Increasing mid-level cloudiness will overspread the west and
southwest mainly after 06Z Monday. 


Issued AT 200 PM MDT Sat Oct 16 2021

Upper-level ridging will continue to be prevalent during the day 
today and into Sunday. With the ridge in place, warmer and drier 
weather is expected through the weekend. However, due to increased 
ground moisture from recent snowfall, near-seasonal temperatures and 
above-criteria minimum RH; fire weather concerns are at a minimum. 
Surface winds will be breezy today with gusts to 25 mph. Sunday will 
bring stronger southwest winds 15 to 25 mph with isolated gusts to 
40 mph through the Wind Corridor. Smoke dispersal will be good to 
very good through the weekend. A potent system is expected to bring 
increased chances of widespread wetting rain in the basins and snow 
to the higher elevations early Monday afternoon through early 
Wednesday before high pressure returns later next week.






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