textproduct: Western and Central Wyoming

KEY MESSAGES

- Some scattered virga showers continue through sunset for points along and south of the I-80 corridor, the main threat wind gusts up to 50 mph.

- Critical fire weather conditions continue Sunday afternoon and evening coupled with low humidity values below 15 percent, hot temperatures, and breezy winds up to 25 to 35 mph.

- Similar conditions through Tuesday, with a weather pattern change beyond that with details unknown besides not as hot temperatures and increased precipitation chances for some of the area.

UPDATE

Issued at 1154 AM MDT Sat Aug 8 2026

Some cloud cover has begun to spread into southern WY this morning, But with very dry air holding firm at the sfc, anything that does fall from these clouds will quickly evaporate before reaching the ground. A wave passing by to the north tonight may also bring some virga/light showers this evening for the Yellowstone region. Otherwise, temperatures are on track today for highs in the upper 90s to near 100, and Air Quality remains poor as strong western wildfires continue.

DISCUSSION

Issued at 110 AM MDT Sat Aug 8 2026

One of the big things that meteorologists look for in forecasting is patterns. And we have had a pattern over most of the past 5 weeks. And that is that the hottest temperatures occurred on weekends. And this one looks to be no exception, although maybe by only a few degrees.

The hottest temperatures will likely be today. Model guidance continues to show 700 millibar temperatures climbing over 20 degrees celsius. And this translates to some portions of the area likely climbing to over 100 degrees this afternoon. Most locations under 5400 feet have at least a 1 in 2 chance of reaching 100 this afternoon, including the Wind River Basin, the eastern Big Horn Basin as well as near Casper. Helping to increase the temperature will be a downsloping southwesterly breeze. And this, combined with the hot temperatures and humidity falling into the single digits, will bring the likelihood of critical fire weather. We currently have a Red Flag Warning in effect for entire area where fuels are critical. Wind is marginally in some of the northern zones of the area. However, with the very dry fuels and low humidity, we will let it go for now. And, it still looks to be a dry day. Mid level moisture will increase a bit in southwestern Wyoming, and may be just enough for a few virga showers to develop. The chance is only around 10 percent at any given spot and with that we left the POPs largely silent. And, like the past few days, we will have areas of smoke around that will bring unhealthy air quality at times.

The operative word for Sunday will be slightly, as in conditions should change, but only slightly. As for the heat, slightly cooler 700 millibar temperatures (about a degree celsius), should also for slightly cooler temperatures, but only a couple of degrees. And, relative humidity will be slightly higher. However, only by a few percent and low enough when combined with the continuing breezy conditions, will likely bring more critical fire weather in the afternoon. And finally, with slightly more instability and slightly more mid level moisture, the chance of a shower or even thunderstorms will go up slightly in southern and western Wyoming. The chance is still at most 1 out of 6 and any shower or storm would likely only bring wind gusts and not any needed rain. And, smoke may be slightly better, but air quality will likely remain unhealthy.

As for next week, it looks like a transition week. Monday and Tuesday still look like rather hot days, with most areas East of the Divide seeing high temperatures in the 90s. A bit more monsoonal moisture may try to work in and bring a few showers and thunderstorms. However, on this day, most would be confined to western Wyoming and still fairly sparse, with generally a less than 1 out of 4 chance. The ridge should then weaken and move to the south and east, bring a more zonal flow. This could allow for more moisture to reach the area and bring an increased chance of convection. There is still a lot of disagreement in guidance with details, so determining a more active day or placement of the most numerous storms is still very difficult at this time. And, temperatures should trend down starting on Wednesday and especially for Thursday and into next weekend when a cold front may pass and bring in some below normal temperatures for the end of next week and into next weekend. However, until we reach that, it looks like more of the same for the next four days. That is hot temperatures, elevated to critical fire weather and little to no chance of meaningful rain.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 430 PM MDT Sat Aug 8 2026

VFR flight conditions are largely forecast through at least 00Z Monday. However, smoke from western United States wildfires is present across Wyoming and could bring localized MVFR visibilities at any point during the TAF period. The placement, timing, and duration of thicker smoke and associated reduced visibilities is very difficult to pinpoint so maintained VFR flight conditions at this time. This will continued to be monitored throughout the period. Breezy winds are expected to decrease to 10kts or less around sunset Saturday. Winds begin to increase at most terminals after 18Z Sunday, with KCPR seeing increased winds as early as 15Z. Frequent gusts in the 20kt to 30kt range can be expected Sunday afternoon. There is up to a 20 percent chance of virga showers until 03Z at KRKS as well as a 10 to 15 percent chance of virga showers at KJAC, KCOD, KRIW, KLND, KBPI, and KBPI from 02Z until 08Z. Because confidence and chances are very low, there is no mention in the forecast at this time. Isolated virga or light rain showers are forecast to develop Sunday afternoon in the vicinity of KRKS, KPNA, KBPI, KCPR, KRIW, and KLND. Confidence is slightly higher (around 30 percent) that KRKS will see direct impacts from light rain Sunday afternoon. Gusty 40kt to greater outflow winds are possible in any virga this evening or Sunday afternoon.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts.

FIRE WEATHER

Issued at 110 AM MDT Sat Aug 8 2026

A combination of hot temperatures, reaching around 100 in some locations, relative humidity falling into the single digits at times and gusty breezes will bring elevated to critical fire weather to all of western and central Wyoming. The strongest wind will be found across southern Wyoming, and the lightest in northern Wyoming. Relative humidity recovery will be remain poor Saturday night, remaining below 40 percent for most locations. s a result, Red Flag Warning is in effect through Sunday evening for all locations with critical fuels.

RIW WATCHES/WARNINGS/ADVISORIES

Air Quality Alert until noon MDT Monday for WYZ001>020-022>030.

Red Flag Warning until 9 PM MDT Sunday for WYZ140-275>283- 285>289-300.