textproduct: Western and Central Wyoming

KEY MESSAGES

- The greatest coverage for showers and thunderstorms today will be across western and northern Wyoming. Isolated to scattered showers and thunderstorms are forecast from Sweetwater County through Natrona County.

- Widespread strong west to southwest winds through late tonight with gusts of 25 to 35 mph. Strong west to northwest winds and widespread gusts of 35 to 45 mph all day Wednesday.

- Elevated to near critical or critical fire weather conditions through Wednesday night due to gusty winds and low relative humidity. A Red Flag Warning is in effect for portions of Natrona County until 8PM Wednesday.

- Near normal temperatures, breezy, low humidity, and limited rain and thunderstorm chances (less than 30 percent) Thursday through Saturday.

UPDATE

Issued at 1231 PM MDT Tue Jun 9 2026

As of Noon/18Z, the cold front mentioned in the morning discussion is roughly located from Rock Springs to Greybull and Sheridan. Surface observations ahead of the cold front have been reporting southwest winds with gusts ranging from 25 mph to 45 mph. These gusty winds are a result of a tightening surface pressure gradient and a southwest to northeast oriented jet overhead. Winds behind the cold front are somewhat lower with west to west-southwest gusts of 20 to 35 mph being reported. These gusty winds will persist throughout the day as the front treks across the state. Relative humidities ahead of front are expected to continue to drop into the 15 to 25 percent range this afternoon, with the lowest humidity forecast over eastern Natrona County. Thus, the Red Flag Warning remains in effect today through Wednesday evening.

The remainder of today's forecast largely remains on track with showers and thunderstorms pushing east across the state behind the front and with the upper level trough axis. The greatest shower and thunderstorm coverage is still expected across western Wyoming through 4PM/5PM. Showers and thunderstorms become more scattered in nature elsewhere across the state through 8PM. One change made this forecast package was increasing the overall footprint of QPF across western and northern Wyoming and from Rock Springs through Natrona County as system treks through. The biggest change occurred from Rock Springs through Natrona County where there looks to be more scattered shower and thunderstorm development as the upper level trough axis pushes over the area. The most likely timeframe for the aforementioned area is between 2PM and 7PM today. The greatest rainfall amounts still reside over western Wyoming with rain amounts in the 0.10" to 0.25" range for Jackson and Star Valleys. Higher elevations of western Wyoming and the Bighorns could see anywhere between 0.25" and 0.75" through sunrise Wednesday. Because the greatest moisture is expected to reside over western and northern Wyoming, the Green River Basin, Bighorn Basin, and from Rock Springs to Natrona County will generally see only a few hundredths of an inch with any showers or thunderstorms.

DISCUSSION

Issued at 130 AM MDT Tue Jun 9 2026

WV imagery continues to show the Pacific northwest upper level trough to the west with the PFJ extending cyclonically through Idaho and into Montana. Jet max of around 120kts continues to deepen the disturbance with ample diffluence aloft. IR shows the cooler cloud tops inching closer to the WY/ID state line that will slowly makes its way west of the Divide bringing with it increasing shower activity by sunrise Tuesday morning expanding to the Divide by late morning. Widely scattered showers and possible isolated thunderstorms through much of the day Tuesday, but with less instability compared to Monday that should see minimal lightning activity in regards to fire weather concerns. Currently, QPF amounts do not look substantial and some mountain snow west of the Divide to include the Winds in the highest of the elevations about 11-12kft. Nothing of note amount wise but intriguing for June and those in the backcountry enjoying the Wyoming great outdoors. It will be helpful for Gannett Peak climbers later in the month keeping the infamous bergschrund closed into early July before it starts its slow opening making for harder glacier travel. The Bighorns will look to get in on the action by Tuesday afternoon as upslope rain shower activity expands east of the Divide for the higher elevations but no snow looks to come to fruition not being as high in stature.

The best chance for storm activity will come mid to late afternoon along the west to east moving cold front clashing with the drier warmer air to the east. The cold front looks to cross the Divide towards sunset Tuesday evening pushing east of the CWA before midnight. This will limit and storm development with more of a lack of moisture content east of the Divide losing the daytime heating Tuesday. Cooler temperatures west of the Divide with earlier FROPA, but temperatures consistent with Monday for points east. Wednesday will be the coolest day of the week with more seasonable temperatures expected CWA wide as the upper level disturbance shifts more northeastward bringing the precipitation chances limited to northern areas of the CWA from Yellowstone across the northern Absarokas and Bighorn Basin to the Bighorn Mountains themselves. Shower activity will exit to the east and northeast by late Wednesday evening and becoming mostly dry overnight into Thursday. Diurnal shower activity for higher elevations expected Thursday afternoon/early evening for Thursday onward as northwest flow aligns back across the northern Rockies. Upper level ridging builds back in across the western United States with increasing convergence aloft to aid in a warming trend Friday and into the weekend.

The other weather element to expect will be winds for Tuesday and Wednesday. Ahead of the aforementioned cold front, expect gusty southwest winds, strongest east of the Divide with gusts up to 40-55mph and in particular the usual wind corridor from Sweetwater to Natrona and Johnson Counties from late Tuesday morning through much of the day. Behind FROPA, expect a shift to west/northwest winds continuing to be quite gusty but not as strong into the overnight hours through Wednesday morning. These winds will once again pick up by late in the morning through sunset before finally subsiding towards sunset and overnight into Thursday as skies improve allowing for more radiational cooling and inversion to set up near the surface. Thursday onward, expect light winds but still breezy back to normal for Wyoming through the end of the week and over the weekend. Northwest to west upper level flow continues into next week with longer term model solutions showing the next best chance for a bigger weather disturbance come mid following week.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1146 AM MDT Tue Jun 9 2026

VFR conditions across nearly all terminals through the TAF period. A cold front has begun to enter western WY which will bring chances for showers and an isolated thunderstorm or two this afternoon/evening. KJAC, KBPI, KPNA, KRKS, KWRL, and KCPR have the best chances (20- 40%) of seeing a brief shower or thunderstorm. Periodic MVFR conditions cannot be ruled out if any showers or storms move overhead any terminals. Precipitation chances begin developing shortly after the start of the period about 19Z through 01Z Wednesday. KCPR will see chances arrive later around 23Z Tuesday through 02Z Wednesday. The other concern this period will be gusty winds across all terminals. Nearly all terminals can expect winds of 15 to 25 knots with periodic gusts of 25 to 35 knots. Some localized gusts of 40 to 50 knots cannot be ruled out especially at KLND, KRKS, KRIW, KCPR, and KWRL. Winds should gradually decrease after sunset becoming breezy through the overnight. Winds once again increase by the end of the TAF period with widespread gusts of 20 to 35 knots for nearly all terminals. Mountain obscuration is expected to persist through the afternoon and evening Tuesday, before improving overnight into Wednesday morning.

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 130 AM MDT Tue Jun 9 2026

Near critical to critical fire weather conditions expected for Tuesday and Wednesday from 9AM to 8PM both days. Red Flag Warning continues for Fire Zone 280 (only zone with critical fuels at this time). Strong winds expected out of the southwest to north of west gusting up to 40 to 55 mph in many areas east of the Divide, and up to 30 to 40 mph to the west. Humidity values will be as low as 10 to 15 percent, driest in the Wind Corridor from Sweetwater to Natrona Counties.

Low humidity values continue for Thursday and Friday into the weekend, but with less wind expected seeing only breezy conditions up to 15 to 25 mph.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM MDT Wednesday for WYZ280.