textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers and isolated thunderstorms will continue to wane through the next several hours this evening. West to northwest wind gusts of 35 to 45 mph will continue through this time and start to decrease after sunset as a cold front moves across the area tonight. Temperatures will be 10 to 20 degrees colder with lows in the 30s and 40s Wednesday morning.

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

- West winds will begin to increase across the area after 8AM Wednesday, with gusts of 35 to 55 mph returning across the area after 12PM. These winds will decrease once again in the evening.

- 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 the 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 any 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 inversions 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 /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 946 PM MDT Tue Jun 9 2026

Continued VFR conditions through the TAF period. Isolated showers will occur across northern Wyoming overnight. Another cold front will drop down from the north into northern Wyoming Wednesday afternoon bringing scattered rain showers to the northern half of the area Wednesday afternoon into Wednesday evening. KJAC has the best chance of impacts, with prevailing -SHRA late Wednesday afternoon into Wednesday evening. PROB30 groups for -SHRA have been added at KCOD and KWRL.

Wind has decreased substantially this evening across the area and will remain around 10 knots tonight at most terminals. Then, wind will increase again Wednesday morning between 15-17Z, with most terminals seeing the increase around 15Z. Wind speeds will be similar to Tuesday afternoon, with 20-30 knots and gusts of 30-40 knots. Some mountain obscuration will occur tonight and Wednesday evening.

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.