textproduct: Western and Central Wyoming

KEY MESSAGES

- Scattered showers and thunderstorms are possible (20% to 30% chance) from 1PM to 8PM today, mainly across the Green River Basin and west.

- Sunny, warm, and dry weather is forecast Friday and especially Saturday with highs in the 60s and 70s.

- Shower chances (20%-30%) increase on Sunday across northern Wyoming. More widespread precipitation chances (30%-50%) exist Monday and Tuesday with near normal temperatures (60s).

UPDATE

Issued at 1224 PM MDT Thu Apr 30 2026

Light snow has ended as of noon/18Z as a positively tilted trough exits Wyoming. Northerly flow behind this trough and 700mb temperatures around -5 Celsius will help keep temperatures this afternoon in the 50s. A weak shortwave will traverse over Idaho and west and southwest Wyoming this afternoon. There will be just enough mid-level moisture and around 250 J/kg of CAPE to support isolated to scattered orographically induced showers and thunderstorms, mainly across the Green River Basin and west. Additionally, a few instances of gusty 25 to 35 mph outflows are possible with dewpoint depressions across the aforementioned locations around 25 to 30 degrees Fahrenheit. Any shower or thunderstorm chances elsewhere across the state will be very limited (up to 20 percent chance) and largely confined to the southern Bighorn and southern Absaroka mountains, including around Dubois. All convection chances end by sunset tonight.

As mentioned in the morning discussion, a cool morning is expected on Friday. Mostly clear overnight skies will promote efficient radiational cooling and allow temperatures to fall into the 20s west of the Divide and 20s to 30s east of the Divide. These cold morning temperatures will not hang around as high pressure builds in during the day on Friday. This high pressure will hang around through at least Saturday and allow for widespread temperatures in the 70s (5 to 10 degrees above normal). Ensemble guidance has been in consensus that the next chance for widespread precipitation will arrive on Monday and Tuesday of next week.

DISCUSSION

Issued at 305 AM MDT Thu Apr 30 2026

As I write this discussion around 2 am, the Wind River Basin and Lander Foothills are getting some well needed moisture, in the form of both rain and snow from a weak 700 millibar circulation that is bringing some northerly upslope flow to the area. Any accumulations would mainly be around Lander, although as of 2:30 am there is only a small coating on the grass. There will likely be an inch or so in Lander, with higher amounts as you head toward Sinks Canyon, again largely on non-paved surfaces. Almost all guidance shows the majority of the precipitation ending by sunrise. All in all, today looks fairly similar to yesterday with another shortwave passing through the area, bringing another round of scattered showers and isolated thunder. Coverage looks slightly less than yesterday, and more concentrated in southern portions of the state where the shortwave will be in the afternoon. Showers should taper off after sunset.

Ridging should then build over the area for Friday and Saturday, and bring a couple of nice Spring days. Friday will start off chilly, but plenty of sunshine and seasonably mild temperatures will bring a nice afternoon. Saturday looks even nicer as flow turns more west to southwesterly bringing warmer temperatures while maintaining sunshine. In addition, wind should remain light to moderate, a luxury this time of year. If you can, get out and enjoy both of these days.

Climatologically, May is the wettest month of the year. And, the chance of showers and thunderstorms may return to the area on Sunday as a cold front drops toward the area on Sunday. Most guidance shows the main impacts across northern Wyoming with this front. However, most of this day looks largely dry and warm across a majority of the area, especially across southern portions of the state.

Cooler temperatures return behind the front Monday. Then we get another chance of more widespread precipitation Monday night and into Tuesday as an upper level low moves toward the area from the West Coast and passes south of Wyoming. The NBM ensemble guidance gives a greater than 1 in 2 chance of greater than a quarter of an inch of QPF across the favored north to northeasterly upslope locations from Lander to Casper from Monday night to Tuesday night. This is still uncertain though as deterministic models have differences of a few hundred miles with the position of the low, impacting placement of the heaviest precipitation. And with the increased cloud cover, temperatures will again be below normal on Tuesday. Following this, ridging builds back over the area. There are uncertainties with precipitation as some guidance has Wyoming on the eastern edge of the ridge so shortwaves could bring showers for the end of the week while others are dry. However, most guidance shows a return to above normal temperatures by next Thursday.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 450 PM MDT Thu Apr 30 2026

VFR conditions will prevail across nearly all terminals through the TAF period. A few showers may linger across portions of southern WY, with KPNA and KBPI possibly seeing a brief shower through 02Z. As a result, brief MVFR conditions may be possible at KPNA and KBPI. Winds may remain breezy at locations such as KRKS and KCOD for another hour or two after the start of the period. Winds then become light across all terminals through the overnight and through much of Friday. SCT- BKN ceilings that have developed this afternoon will gradually clear out overnight with widespread SKC for Friday.

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.