Latest ZFP from WFO RIW

		
National Weather Service Local Forecast for Star Valley Ranch
Updated: Fri May 02  6:59 am MT

Today... Sunny, with a high near 65. Calm wind becoming south
around 6 mph in the afternoon. 

Tonight... Mostly clear, with a low around 37. Light and
variable wind becoming east northeast 5 to 7 mph after midnight. 

Saturday... Sunny, with a high near 70. Light and variable wind
becoming southeast 5 to 9 mph in the afternoon. 

Saturday Night... Mostly clear, with a low around 40. West wind
around 6 mph becoming light and variable  after midnight. 

Sunday... Showers likely and possibly a thunderstorm after
noon.  Mostly sunny, with a high near 69. East southeast wind 3 to 6
mph.  Chance of precipitation is 60%.

Sunday Night... Showers likely and possibly a thunderstorm
before midnight, then a slight chance of showers.  Mostly cloudy, with
a low around 42. South wind around 6 mph becoming calm  in the
evening.  Chance of precipitation is 60%.

Monday... A chance of showers, then showers and possibly a
thunderstorm after noon.  High near 61. Calm wind becoming north
northeast around 6 mph in the afternoon.  Chance of precipitation is
80%.

Monday Night... Showers likely and possibly a thunderstorm
before midnight, then a chance of showers.  Mostly cloudy, with a low
around 39. Chance of precipitation is 60%.

Tuesday... A chance of showers, with thunderstorms also
possible after noon.  Partly sunny, with a high near 61. Chance of
precipitation is 30%.

Tuesday Night... A 20 percent chance of showers before
midnight.  Partly cloudy, with a low around 38.

Wednesday... Mostly sunny, with a high near 66.

Wednesday Night... Partly cloudy, with a low around 41.

Thursday... A chance of showers and thunderstorms.  Sunny, with
a high near 68.

		

Latest AFD from WFO RIW

		
074 
FXUS65 KRIW 021115
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
515 AM MDT Fri May 2 2025

.KEY MESSAGES...

- Warm and dry conditions today through Saturday, with temperatures 
  peaking 15 to 20 degrees above normal.

- A system will begin to push into the area Sunday, returning
  rain showers to western Wyoming Sunday afternoon. 

- Widespread rain and mountain snow is expected Monday and
  Tuesday, especially across central and southern Wyoming.

&&

.DISCUSSION...
Issued at 437 AM MDT Fri May 2 2025

A strengthening ridge will be the dominant weather feature for the 
next couple of days as it builds in from the west. Mostly clear 
skies are expected today, with temperatures peaking about 5 degrees 
above normal for most locations. Wind will remain fairly calm, 
making for a pleasant weather day across the area. This trend 
continues on Saturday as the ridge reaches its maximum extent over 
Wyoming; 700mb temperatures will rise to near 10C, helping highs 
peak 15 to 20 degrees above normal. Humidity will drop into the 
teens both today and Saturday across lower elevations, though 
relatively light wind should help to mitigate fire weather concerns 
during this period.  

By Sunday the ridge will begin to break down as a longwave trough 
moves onto the West Coast and an associated 500mb low deepens across 
southern California. This will return precipitation chances west of 
the Continental Divide, though the majority of the area is expected 
to see another warm and dry day. It will be breezier ahead of the 
approaching system, which may lead to an increasing fire weather 
concern for southern and central Wyoming. 

The low will drift northeasterly on Monday, sending a surge of 
moisture to the Rockies. This will spread rain and mountain snow 
widely across the area through Tuesday. There is still some 
inconsistency on where the low will set up as it approaches Wyoming 
which will have an impact on how much moisture is realized. 
Regardless, the general track of the low to our south should lead to 
a respectable precipitation event for much of the area, especially 
across central Wyoming where an upsloping, northeasterly flow 
develops. Currently, forecast precipitable water values are over 
0.60" for much of the area. This is near the climatological maximum 
for this time of year at KRIW (SPC Sounding Climatology). For 
context, this value is only right around the mean daily precipitable 
water values seen in July. With temperatures expected to remain on 
the warmer side, snow will be limited to the mountains, with the 
most along the eastern slopes of the Wind River Range. Given the 
warm weekend followed by a decent rain event, river flood potential 
may be elevated early next week.

Further ahead, ensemble cluster guidance indicates a quick return to 
rising 500mb heights by Wednesday. This favors warmer and drier 
conditions through the end of next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 515 AM MDT Fri May 2 2025

Dry and VFR flight conditions expected this TAF period as high 
pressure dominates the region. Winds will largely remain light 
(10kts or less) at all terminals.

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.

&&

$$

DISCUSSION...Myers
AVIATION...Gerhardt