textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers and thunderstorms have started to wane this evening, with isolated showers and storms remaining possible from Sweetwater County to Natrona County through 10PM.

- A cold front will progress southward this evening, with gusts of 45 to 55 mph possible across Johnson County, northern portions of the Bighorn Basin, and the Wind River Basin in the wake of the front. Temperatures will be 10 to 15 degrees cooler tonight as a result.

- Breezy southwest winds with gusts of 25 to 35 mph will return across areas west of the Divide Monday. Elevated to critical fire weather conditions will return to central and southern portions of the forecast area.

- A strong cold front will impact the region starting Tuesday, with the possibility for strong to high winds at times over wind prone locations. Cooler temperatures will arrive over western portions Tuesday, spreading to the rest of the forecast area on Wednesday.

UPDATE

Issued at 1242 PM MDT Sun Jun 7 2026

Thunderstorm coverage is expected to increase over the next few hours as instability builds. This will be focused mostly east of the Divide where SBCAPE values will reach 500-1000 J/kg. The strongest storms are still expected in the eastern Bighorn Basin and across Johnson County where instability and shear (30-40 knots bulk) will be maximized. A narrower band of instability should also develop farther south, extending through Sweetwater County within a relatively more moist airmass. Stronger storms today will be capable of occasional large hail and strong wind gusts of 60 to 70 mph. Convection will wane by late evening, with most of this activity to our east by midnight.

DISCUSSION

Issued at 200 AM MDT Sun Jun 7 2026

WV imagery currently shows the deep upper level trough across the Pacific northwest with the PFJ pushing cyclonically around it with a positive tilt just to the west of the state. IR shows the cooler cloud tops over eastern Idaho into central Montana that will slowly push east into the CWA by Sunday morning expanding throughout the day. Some light rain showers across the west that will dissipate by sunrise with another round of scattered thunderstorms expected to develop by late morning across the Bighorn Basin. Gusty outflow winds expected with this occurrence but severe weather is not expected through early afternoon. As this pushes northeast by mid afternoon ~3-4PM, another area of development expected to off the leeward side of the Absarokas by 4-5PM pushing across the north central portions of the basin expanding to the Bighorns. These look to form more of a line across the pre-frontal troughing with winds again the main concern with possible severe thresholds being met.

Attention turns to the more discrete cells come 6PM onward towards sunset as the weak storms across Sweetwater County push across Natrona into Johnson County. This will be when hail could be more of a threat before quickly pushing northeast out of the CWA before sunset around 8PM. With the ample surface convergence and modest lapse rates, larger hail possible with moderate confidence for severe thresholds up to a quarter. CAPE values over 1500 J/kg ahead of FROPA will be conducive to this occurrence with low level shear aiding in hail growth over 30 knots. The more upscale growth will occur after sunset and northeast of the CWA into western South Dakota. These strong to severe storms for hail potential will be short lived for our CWA with the time frame of concern between 6-8PM. Otherwise, any other stronger storms for the eastern Bighorn Basin across the Bighorns and northern Natrona County will be more of a wind threat but below severe thresholds at this point in time. A long Sunday night looks to be in store severe wise for Rapid City and point north and east into Monday morning.

Beyond the storm activity, expect FROPA to occur north to south by late afternoon and into the late evening hours. Warm temperatures ahead of the front will still give way to above average temperatures but not record breaking as it was Saturday due to the increased cloud coverage with this first shortwave. Fire weather conditions expected to be near critical to critical ahead of FROPA with gusty southwest winds to develop by mid to late Sunday morning, strongest across Sweetwater to Natrona Counties for the wind corridor up to 30 to 40 mph likely. Winds shift with more of a northern component behind FROPA pushing through the CWA after midnight and into early Monday morning diminishing by sunrise.

Continued active pattern with the aforementioned L/W trough to the northwest with a multitude of shortwaves through Thursday. With cooler temperatures, severe weather is not expected but expect a daily afternoon/evening dose of scattered storm activity along with elevated fire weather danger as well. The coolest day of the week looks to be Wednesday with a stronger cold front with the the more widely scattered rainfall activity expected. Beyond Thursday, the low finally exits to the east as increased convergence aloft and upper level ridging builds back in for Friday and into next weekend with a warming and dry trend expected.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 950 PM MDT Sun Jun 7 2026

Conditions will remain VFR for most terminals through the TAF period. There's about a 50% chance of MVFR ceilings at KCPR behind the cold front from 08-15Z. Precipitation chances will be low at most terminals this TAF period, but there's about a 30% chance of some rain showers at KPNA from 12-15Z.

Wind will shift northerly behind the front tonight into Monday morning and be breezy at KCPR. Wind will increase at most terminals Monday afternoon, but much lighter than Sunday. Generally, wind will be 10-15 knots, with gusts up to 25 knots through Monday afternoon, dropping off by 02Z. Mountain obscuration will occur around Casper Mountain and the eastern slopes of the Bighorn Mountains tonight through Monday 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 200 AM MDT Sun Jun 7 2026

Near critical to critical fire weather conditions expected for Sunday afternoon and evening due to gusty southwest winds up to 30 to 40 mph and low relative humidity values down to 8 to 12%. Although most fire weather zones are green for fuels (outside of much of Natrona County), fire weather will be of concern for Sunday. Scattered thunderstorms are expected from eastern Bighorn Basin/Fremont County to Natrona/Johnson Counties for late Sunday afternoon and early evening. Gusty outflow winds possible up to 50-60 mph with some of the stronger storms. Active weather pattern continues into much of the work week, but with not as warm temperatures giving way to higher humidity values and only elevated fire weather concerns after Sunday.

RIW WATCHES/WARNINGS/ADVISORIES

None.