textproduct: Western and Central Wyoming

KEY MESSAGES

- Virga showers will remain possible over portions of Natrona County through 8PM. Brief wind gusts of 40 to 55 mph could occur with these showers.

- Rain and thunderstorm chances (40-90 percent) are forecast late tonight into Tuesday across western Wyoming and again on Wednesday across northern Wyoming.

- Gusty southwest to west winds across the entire area on Tuesday and Wednesday with gusts of 35 to 50 mph. There is high confidence in elevated to near critical fire weather conditions for most locations, especially Wednesday.

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

UPDATE

Issued at 105 PM MDT Mon Jun 8 2026

19Z water vapor imagery shows southwest flow across the Intermountain West. Forecast guidance has remained consistent that a weak area of vorticity, embedded within the southwest flow aloft, will traverse over Sweetwater, Natrona, and Johnson Counties this afternoon. As it does so, there looks to be just enough mid level moisture and support aloft for isolated virga showers to develop across the aforementioned areas. The low levels are dry with dewpoint depressions of 40 to 55 degrees Fahrenheit, so little to no liquid is expected to make it to the surface. However, any virga or light rain showers could be capable of 40 to 55 mph gusty outflows roughly from Rock Springs to Midwest between 2PM and 8PM. Confidence in thunderstorms is low (10 to 20 percent) due to weak height rises aloft suppressing overall convective development. That being said, if a thunderstorm were to develop, it would most likely occur across Natrona County into southern Johnson County where boundary layer CAPE will be in the 200 to 500 J/kg range.

The cold front looks to approach western Wyoming between 4AM and 6AM Tuesday and bring rain and thunderstorms to most of western Wyoming on Tuesday. The front will slowly trek eastwards during the day on Tuesday and tighten the pressure gradient as it does so. There is high confidence in gusty 25+ mph winds both Tuesday and Wednesday across the entire forecast area. These gusty winds, combined with low relative humidity, will create elevated to near critical (or critical across portions of Natrona County) fore weather conditions across much of the state from 9AM to 8PM on Tuesday and especially Wednesday. Thus, where fuels are cured (portions of Natrona County), the Fire Weather Watch has been upgraded to a Red Flag Warning from 9AM Tuesday until 8PM Wednesday.

DISCUSSION

Issued at 130 AM MDT Mon Jun 8 2026

IR shows cooler cloud tops over Idaho mainly associated with the upper level low over the Pacific Northwest. WV depicts the PFJ around it pushing into much of Montana with jet max up to 120-130kts allowing for the low to continue to slowly deepen with increased divergence aloft. Any shower activity has diminished and pushed east of the CWA with mainly dry conditions expected Monday. However, a couple of isolated storms look to develop over eastern Sweetwater to southern Natrona counties after 2-3PM Monday afternoon exiting east and northeast by 6-7PM. Severe weather is not expected, but stronger outflows may be had if enough of the cap breaks with warmer 700mb temps up to 40-50 mph possible but confidence low at this point in time (20-30%).

The next shortwave around the aforementioned low will begin to push in out west from Idaho after midnight into early Tuesday morning. More widely scattered rain shower and thunderstorm activity expected but severe weather again not expected due to not as warm temperatures, and thus, less instability to be had for these storms to tap into west of the Divide. These spread east after sunset Tuesday night into Wednesday, with that being the "coolest" day of the week behind a stronger cold front. Ahead of the front, expect gusty southwest winds east of the Divide, possibly seeing widespread gusts over 50 mph pushing close to high wind criteria. Confidence not great on how strong the winds will be, and thus, no headlines are issued at this time. Behind the aforementioned cold front, expect winds to be more west to north of west with continued stronger gusts, especially east of the Divide once again. The highest winds look to be pinpointed across the Wind Corridor as expected from Sweetwater to Natrona Counties and up to Johnson. Buffalo and points north coming down from Sheridan look to be a point of emphasis to keep an eye on, as the models have not handled how high winds can be here, especially after Sunday evening's event behind the weaker of the cold fronts to affect the CWA days apart.

The upper level low looks to fill and start to progressively push east across the upper Rockies Wednesday night. Any shower activity lingering into Thursday morning will go with it, as dry conditions push back in for the rest of the work week and into the weekend. Increased convergence and a building upper level ridge pushes over the region Thursday into Friday, and especially over the weekend. Back to warmer than average temperatures going into next weekend. Northwest flow aloft continues during this timeframe, so weak higher terrain storms are still possible each afternoon and early evening based on diurnal trends. Longer term models continue this pattern not seeing any break in this upper level flow until at least 10 days out.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 513 PM MDT Mon Jun 8 2026

Ongoing weak convection between KRKS and KCPR will be capable of gusty outflow wind of 35-45kts, locally higher, until around 02Z/Tuesday. Gusty southwest surface wind 12-25kts fades around sunset Monday, with southerly wind 7-10kts overnight. KCPR, however, sees a renewed surge of easterly wind 10-15kts for 6 to 8 hours. As the upstream trough nears Wyoming, southwesterly surface wind will increase late tonight and Tuesday morning over the region. These speeds steadily increase between 15Z-19Z/Tuesday with widespread 15- 30kt sustained westerly wind by early Tuesday afternoon. All terminals to be VFR through the forecast period with the possible exception of KJAC, as the trough reaches far west Wyoming Tuesday morning. There is a 30-50 percent chance of MVFR ceilings in light rain as the main moisture push moves through KJAC after 12Z/Tuesday, which has necessitated a PROB30 group. A cold front accompanied by a wind shift to the west and northwest pushes east during the afternoon. Mountain tops along and west of the Continental Divide frequently obscured after 10Z/Tuesday.

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 105 PM MDT Mon Jun 8 2026

Elevated to near critical fire weather conditions expected Monday with strongest winds west of the Divide gusting up to 25 to 35 mph out of the southwest. Humidity values in the 10 to 20 percent range for much of the area.

Near critical to critical fire weather conditions expected for Tuesday and Wednesday from 9AM to 8PM both days. The Fire Weather Watch has been upgraded to a Red Flag Warning for Fire Zone 280 (only zone with critical fuels at this time). Stronger winds expected out of the southwest to west gusting up to 40 to 50 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, but with less wind expected seeing only breezy conditions up to 15 to 25 mph.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 9 AM Tuesday to 8 PM MDT Wednesday for WYZ280.