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Latest ZFP from WFO RIW

		
National Weather Service Local Forecast for Star Valley Ranch
Updated: Tue Oct 04  3:42 pm MT

This Afternoon... Sunny, with a high near 65. Northwest wind
around 9 mph. 

Tonight... Clear, with a low around 35. North northwest wind 5
to 9 mph becoming light and variable. 

Wednesday... Sunny, with a high near 69. East southeast wind 5
to 7 mph becoming west in the morning. 

Wednesday Night... Mostly clear, with a low around 36. North
northwest wind 5 to 7 mph becoming east southeast in the evening. 

Thursday... Sunny, with a high near 69. Light and variable wind
becoming west northwest around 6 mph in the afternoon. 

Thursday Night... Mostly clear, with a low around 36. Northwest
wind around 6 mph becoming light and variable. 

Friday... Sunny, with a high near 68. Light and variable wind
becoming west northwest 5 to 7 mph in the afternoon. 

Friday Night... Partly cloudy, with a low around 37.

Saturday... Mostly sunny, with a high near 68.

Saturday Night... Partly cloudy, with a low around 37.

Sunday... Sunny, with a high near 67.

Sunday Night... Mostly clear, with a low around 36.

Columbus Day... Sunny, with a high near 65.

		

Latest AFD from WFO RIW

		
516 
FXUS65 KRIW 041906
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
106 PM MDT Tue Oct 4 2022

.SHORT TERM...(This afternoon through Wednesday night) 
Issued at 100 PM MDT Tue Oct 4 2022

The large upper-level low pressure system has moved eastward over 
east-central SD this morning, with lingering clouds around the 
Bighorns and Johnson and Natrona Counties. There is a very slight 
chance of showers over the Bighorns this afternoon as a result, 
but confidence is low. Fog developed early this morning from the 
lower elevations of Yellowstone south into Jackson Hole, but has
burned off during the late morning hours. Otherwise, mostly clear
skies will prevail over the forecast area with relatively light
surface winds. Some areas over central WY as well as western into
SW WY could see NW winds of 10-12 mph with gusts 15-20 mph. 
Upper-level high pressure over the western US moves eastward, 
kind of "folding over" from ID/western MT into western WY 
overnight. Skies should be mostly clear overnight, though some fog
should redevelop over the lower elevations of Yellowstone and 
into the northern parts of Jackson Hole. Not confident enough to 
put patchy fog in the forecast for the town of Jackson and Jackson
airport though. Overnight temperatures will again be on the 
chilly side with most of the western valleys reaching 32 F or 
lower just before sunrise. With the eastern edge of high pressure 
over WY Tuesday, the surface pressure gradient will direct surface
winds from NE to SW during the afternoon. Winds of 10-12 mph with
gusts 15-20 mph are possible in some locations from central into 
southern WY, with lighter winds elsewhere. Cody to Meeteetse may 
see gusty east winds though. Some clouds will develop over the 
mountains during the afternoon as well for a very nice early 
October day. Temperatures will be 4-6 degrees above normal in the 
mid 60s to low 70s due to 700mb temps from +4 to +8 C. Wednesday 
night into early Thursday morning should see mid- to high-level 
clouds start pushing into northern WY from the north as an 
approaching shortwave trough enters far NE MT. The HRRR and other 
high res models are indicating that north winds will push into far
northern WY before sunrise Thu morning.

.LONG TERM...(Thursday through Tuesday)
Issued at 105 PM MDT Tue Oct 4 2022

An amplified ridge remains to our west with the axis along the 
Pacific Coast through Saturday. This keeps generally dry, northwest 
flow aloft across Wyoming. Surface high pressure drops south through 
the Northern Plains Thursday pushing a backdoor cold front to the 
east slope of the Continental Divide Thursday afternoon and evening. 
Other than dropping daytime highs a few degrees and perhaps igniting 
isolated convection in the northern mountains, there is little 
impact associated with this boundary. The next shortwave clips 
eastern Wyoming Sunday as it slides southeast. Similar to Thursday, 
this wave brings little more than isolated mountain convection in 
the north and a slight drop in temperatures across the east.

Beyond Sunday, model differences begin to become more noticeable. 
There seems to be some general agreement that the ridge may begin to 
break down and at least usher in progressive zonal flow. Overall, 
this would lead to mild temperatures through Monday along with a 
better chance of precipitation Tuesday as Pacific Moisture reaches 
the Rockies. Also, increasing westerly wind would become more likely 
Tuesday. By Tuesday, and certainly beyond, the range of solutions 
varies widely among ensemble and deterministic model solutions. 
Options range from 1) the ridge dampening but holding, 2) more 
progressive westerly flow, and 3) a deepening trough in the Northern 
Rockies accompanied by a more vigorous cold front. For example, GFS 
ensembles for KRIW on Tuesday, October 11, show highs ranging from 
the 20s to the lower 70s, generally clustering in the 50s and 60s. 
At this range, the solution offered by the blended model is 
certainly the way to go, an option leaning toward seasonal 
temperatures, increasing west wind, and a better chance of showers.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday)
Issued at 1124 AM MDT Tue Oct 4 2022

All terminals to be VFR through the forecast period. Cyclonic 
northwesterly flow aloft lingers through the day leading to isolated 
afternoon convective showers over the Bighorns. Otherwise, SKC west 
of the Continental Divide, with FEW-SCT070 to the east until 
sunset. Surface wind speeds will be less than 10kts throughout.

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

&&

.FIRE WEATHER...
Issued AT 101 PM MDT Tue Oct 4 2022

High pressure is moving into WY from the west today, with some 
clouds over central WY and a very slight chance of showers over the 
Bighorn mountains.  Winds this afternoon will be light to moderate 
with some areas seeing NW winds and gusts 15-20 mph. Humidity values 
should remain above 25 percent and temperatures will be just above 
normal. Skies will clear overnight with some fog expected again 
from Yellowstone into northern parts of Jackson Hole. Overnight 
temps will again be chilly with good humidity recovery. High 
pressure settles in Tuesday for warmer temps from the 60s to low 
70s in the lower elevations. Winds again will be light with some 
areas seeing NE winds and gusts 15-20 mph. High clouds will start 
pushing into northern WY Wed night, and a weak cool front may push
into northern WY by 0600 Thu. Thu will see cooler temps and a 
north wind east of the divide, with some light showers around the 
mountains during the afternoon.  Warm and dry west of the divide.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE. 

&&

$$

SHORT TERM...McDonald
LONG TERM...Jones
AVIATION...Jones
FIRE WEATHER...McDonald

		

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