Latest ZFP from WFO RIW

		
National Weather Service Local Forecast for Star Valley Ranch
Updated: 27 Jan 21:01 pm MST

Tonight... Patchy fog after 3am.  Otherwise, clear, with a low
around -5. Wind chill values as low as -15. Southeast wind around 6
mph. 

Friday... Patchy fog before 11am.  Otherwise, sunny, with a
high near 19. Wind chill values as low as -20. Southeast wind 6 to 8
mph. 

Friday Night... Areas of fog after 2am.  Otherwise, mostly
clear, with a low around -2. Wind chill values as low as -15.
Southeast wind around 8 mph. 

Saturday... Areas of fog before 11am.  Otherwise, sunny, with a
high near 24. Wind chill values as low as -15. South southeast wind 5
to 8 mph becoming southwest in the afternoon. 

Saturday Night... Areas of fog after 1am.  Otherwise, mostly
clear, with a low around 2. East southeast wind around 5 mph. 

Sunday... Areas of fog before 11am.  Otherwise, sunny, with a
high near 35. East southeast wind around 6 mph becoming west southwest
in the afternoon. 

Sunday Night... A 20 percent chance of snow showers after 11pm.
 Partly cloudy, with a low around 14. South wind around 7 mph. 

Monday... Snow showers likely, mainly after 11am.  Mostly
cloudy, with a high near 28. Breezy.  Chance of precipitation is 70%.

Monday Night... A 40 percent chance of snow showers.  Mostly
cloudy, with a low around 12.

Tuesday... A 40 percent chance of snow showers.  Mostly cloudy,
with a high near 22.

Tuesday Night... A slight chance of snow showers.  Mostly
cloudy, with a low around 1.

Wednesday... A slight chance of snow showers.  Partly sunny,
with a high near 12.

Wednesday Night... A slight chance of snow showers.  Mostly
cloudy, with a low around -2.

Thursday... A slight chance of snow showers.  Partly sunny,
with a high near 19.

		

Latest AFD from WFO RIW

		
502 
FXUS65 KRIW 272225
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
325 PM MST Thu Jan 27 2022

.SHORT TERM...(This evening through Saturday night)
Issued at 208 PM MST Thu Jan 27 2022

The light snow has ended with the Lander area the winner with 2 to
4 inches. Amounts elsewhere were an inch or less across the
central and east zones. Clouds have been on the decrease over the
region with lingering clouds in the east and south zones this
afternoon. Temperatures are in the 20s to lower 30s at 21Z with 
some teens in the far west valleys. The forecast challenge 
tonight will be the low temps. With a clear to mostly clear sky 
expected, light wind, and cold temps aloft, low temps will be more
in line with January. Lows will be in the single digits and teens,
with 5 to 15 below zero in the western valleys. I did add patchy 
fog to the far west valleys for late tonight into Friday morning. 
I think late Friday night into Saturday morning will see a little 
better chance of low clouds or fog in the far west valleys into 
parts of Yellowstone National Park. I also included this fog late 
Saturday night into Sunday morning as well. 

Friday and Saturday will be dry. Breezy to windy areas will occur
in the central wind corridor and in parts of NW WY Friday into 
Friday night. A little less wind in these areas Saturday, but 
still breezy. Light wind in most valleys and basins. The forecast
challenge Friday and Saturday will be the high and low temps.
Temperatures will be warming aloft Friday and Saturday, which will
help moderate the high country and foothill locations. As for the 
lows, they will be quite cold in the western valleys Friday night 
and Saturday night with sub-zero readings. East of the divide, 
lows Friday night and Saturday night will be in the single digits
and teens in the basins, with 20s in the foothill locations and 
around Casper. As for high temps, Friday will see 30s east of the 
divide with 40s in the snow free areas of Johnson county, northwest
Fremont county, and parts of the Cody foothills. In the western 
valleys, highs will be in the teens and 20s. On Saturday, highs 
will be a few degrees milder east of the divide, but the far west 
valleys will be trapped in the inversion with mid teens to lower 
20s expected. 


.LONG TERM...(Sunday through Thursday)
Issued at 208 PM MST Thu Jan 27 2022

January will go out like a lamb, but February looks to roll in like 
a hungry lion that hasn't eaten in a few days. I may have exaggerated 
that a bit, however the pattern change will be a quite a bit of a 
shock to the system, especially when considering the mild and dry 
winter much of the region has experienced so far. 

Sunday will be mild with much above normal temperatures expected 
across much of the region. Some locations in the Cody Foothills and 
eastern Johnson County may even see temps climb into the low 50s 
Sunday afternoon. Monday, high temps will be similar, though likely 
a degree or two colder as an initial push of cold air begins to 
filter into the region along with some precipitation. Snow will 
begin across the far west sometime Monday morning to early 
afternoon. Models are a bit iffy on timing/propagation overall still 
with this but are in decent enough agreement on a Monday/Monday 
afternoon start time. Snow will move across the northern Basins and 
Bighorns by Monday afternoon/Monday night. Not looking at a massive 
snow maker, but certainly enough to probably necessitate some 
highlights at least across the west and maybe north. 

This system continues to dig south through Tuesday. As it digs, a 
strong Arctic front will slide southward Tuesday. Expect Tuesday's 
highs to be early in the morning with temperatures falling through 
the day. 700mb temps are progged to drop to -22 to -25C by Wednesday 
morning. This will bring in the coldest air of the season for many 
locations. Temps will plummet well below zero across much of the 
region by Wednesday and highs will only be in the single digits to 
maybe (with an emphasis on maybe) low teens Wednesday afternoon. The 
Arctic front will also drag some snow with it, with likely light 
snow showers occurring across much of the region Monday night into 
Tuesday, including across the basins east of the Divide. Snow 
amounts this far out are a guessing game, but expect at least a 
dusting across much of the region with more where those pesky snow 
bands ultimately set up. Northwest flow will keep snow showers 
across the west into Thursday, while areas east of the Divide should 
remain dry after Tuesday. The cold will stick around for Thursday 
with clear skies resulting in likely even colder lows Thursday 
morning. Some areas may begin to mix out Thursday afternoon, but 
most areas will likely continue to struggle to get out of the single 
digits to teens. 

In terms of the forecast grids, models are having a hard time 
picking up on the colder air, so dropped Max/Min Temps from NBM 
significantly for Wed/Thurs. Also added PoPs for Monday 
Night/Tuesday, as NBM has a hard time picking up on the banded 
snow shower activity east of the Divide in these scenarios. Went 
with broad brushed 20 to 30% PoPs across the eastern basins Monday
night through early Tuesday with lingering higher PoPs across 
Natrona County Tuesday morning. Future shifts will continue to 
massage these grids as we get closer to the event. Keep in mind we
are still almost a week out, so models have plenty of time to 
resolve the more complex features of this event. 

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday)
Issued at 208 PM MST Thu Jan 27 2022

Prevailing VFR at all sites through the end of the TAF period with 
mostly SKC west of the Divide with some scattered high clouds 
lingering east of the Divide. Gusty winds will develop at several 
locations, namely KCOD, KCPR and KRKS by early Friday morning and 
continue through the rest of the period. KCPR will see the strongest 
winds with frequent gusts up to 30 to 35 likely through Friday 
afternoon.

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 208 PM MST Thu Jan 27 2022

Dry weather will occur tonight through Sunday. Breezy to windy
weather will occur in the central wind corridor zones and in parts
of the northwest Friday and Saturday. Temperatures will be
moderating through the weekend, but snow covered valleys and
basins will be slower to warm up. Mixing heights will be low the
next few days which will equate to poor to fair smoke dispersal in
most locations. 

&&

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

&&

$$

SHORT TERM...AR
LONG TERM...Hensley
AVIATION...Hensley
FIRE WEATHER...AR