textproduct: Western and Central Wyoming

KEY MESSAGES

- Widespread critical fire weather conditions continue through the weekend given low humidity, gusty wind, and hot temperatures.

- Chances (10-15%) for very isolated showers and thunderstorms tonight mainly across northern and western Wyoming.

- Thunderstorm chances become more widespread Sunday (15-40%), with a couple of stronger storms possible across the eastern Bighorn Basin and Johnson County.

UPDATE

Issued at 105 PM MDT Sat Jun 6 2026

Today's forecast of hot and dry conditions is on track, though scattered high clouds have delayed heating slightly. Still, peak temperatures should reach near 100 degrees in portions of the Bighorn Basin, as well as northeastern Johnson County. There are currently some weak, isolated showers across northwestern Wyoming, and there are still indications that there may be additional development later today as cyclonic flow increases. Critical fire weather conditions are the more widespread impact given the elevated southwest wind. Similar concerns will be noted for Sunday, with the additional threat of more widespread and robust convection as the trough begins swinging in.

DISCUSSION

Issued at 206 AM MDT Sat Jun 6 2026

The long-awaited buckling of the midlevel flow has begun to strengthen across the western US, and will bring the warmest day of 2026 to most of the state. H7 temperatures are already running 12-14C, and will be peaking this afternoon between 16 and 18C, which translates to the sfc as highs in the upper 80s to the upper 90s. Isolated readings at 100 degrees may be noted along the lowest elevations of the Bighorn Basin for a few hours this afternoon. Temperatures aloft will be cooler for NW WY, which is closer to the incoming trough, which will keep temps more modest in the 70s this afternoon.

The southwest flow around the approaching trough will be very dry, and with dry air already at the sfc, will mix well down to the sfc this afternoon. Wind gusts will reach 35 to 50 mph through the afternoon, picking up around noon and continuing into the early evening. Humidity levels will also crash down this afternoon, staying below 10 percent through the afternoon. This leads to critical fire weather concerns all day.

Tonight, the advancing trough moves off the PacNW coast into the Northern Rockies, pushing the heat ridge eastward and opening up most of the state for increased moisture. There is a hint in some of the convective models that today's heating may be enough to tap the leading edge of the trough to spark a few showers even into central WY this afternoon, but this will be battling against the subsidence with the ridge, so this area may be limited to some increased CU. The better chances for showers first builds into the NW Parks this evening and overnight as the first lobe of the trough passes through. The next band then sets up somewhere in central WY during Sunday afternoon, influenced by an instability axis aloft. As the trough moves east, an enhanced area of shear builds into northern WY, which will also be influenced by terrain shear off the Bighorn Range. Strongly sheared environment and instability could lead to thunderstorms quickly strengthening across Johnson County during the afternoon, with a quickly increasing threat for hail and very strong winds. SPC has this area in a slight risk on Sunday, and will need to monitor for final timing.

Into early next week, the main trough shifts east, putting the axis along the Rockies for the first half of the week. Right now, this puts the northern half of the state in a more showery pattern through most of the upcoming week.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 407 PM MDT Sat Jun 6 2026

Gusty 25kt to 35kt southwest winds will be ongoing at the start of the TAF period, with occasional gusts up to 40kt possible. These gusty winds are forecast to diminish by 02Z/03Z Sunday. Overnight winds are expected to be under 11kt at all terminals. Winds quickly increase between 14Z and 19Z at all terminals, with frequent gusts of 25kt to 35kt.

There is a 10% chance of a shower or virga at KRKS and KCPR through 03Z Sunday. Low light rain chances exist across western Wyoming between 05Z and 09Z Sunday and brings a 30 percent chance of light rain to KJAC. Isolated to scattered shower and thunderstorm chances are forecast on Sunday, with a 30 percent chance at KJAC, KRKS, and KWRL. A heavier shower or thunderstorm could result in brief periods of MVFR visibilities, but confidence in occurrence and duration is low at this time. Showers are forecast to develop in the areas of KCOD, KBPI, and KPNA for a few hours on Sunday. However, confidence is around 20 percent in anything actually impacting the aforementioned three terminals.

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 Sat Jun 6 2026

Critical/near-critical fire weather conditions will be widespread across the area through at least early next week. An incoming system will also increase the lightning and outflow wind threat starting Sunday, as isolated thunderstorms move northeast across the area. The near-surface conditions will remain dry, so much of this may be virga. In addition to the background gusty southwest wind, this activity could produce strong and erratic wind gusts of 50 to 60 mph.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM MDT Sunday for WYZ280.