textproduct: Western and Central Wyoming

KEY MESSAGES

- Another hot day today with elevated to critical fire weather for most of the area. Isolated showers and storms with strong wind gusts in the afternoon, mainly across southern Wyoming.

- Hot temperatures with isolated showers and thunderstorms continue into Monday and Tuesday.

- A pattern change begins Wednesday and especially later next week with cooler temperatures and increased moisture bringing a better chance of showers and thunderstorms.

DISCUSSION

Issued at 1256 AM MDT Sun Aug 9 2026

It is said that the weather pattern often repeats itself. And the pattern for this week is no exception. The past couple of heat waves we had, the warmest temperatures occur over the weekend. Hot temperatures linger into early the next week. And then, monsoonal moisture really begins to increase and with the increased cloud cover and precipitation coverage, temperatures drop off, probably to below normal levels by the end of the week. And, with what happened with the best couple of monsoonal events, the models will handle the placement and timing of the showers rather poorly.

And example is tonight, they did have the virga showers in southern Wyoming. But they had nothing in northern Wyoming. The also did not have anything lingering across the south after midnight, and we have that as well. However, as for today, the large majority of the area will have another hot and dry day, although somewhat more cloud cover could lower temperatures a degree or two. It will still be above normal across most of the area though. And like yesterday, critical fire weather is likely across most of the area with humidity remaining below 15 percent and a gusty breeze developing in the afternoon. As for convection, we did increase coverage somewhat, expanding it into the southern Wind River Basin this afternoon. Like yesterday, with the very dry low levels, it would likely only be virga. However, with the large dew point depressions (up to 70 degrees in some locations), we could have some strong wind gusts, possibly over 50 mph. This has the potential to be a "Little Green Blob" day. Coverage still looks sparse though, generally less than a 1 out of 4 chance. And, we will continue to have areas of smoke bringing poor air quality.

Monday and Tuesday look fairly similar. With 700 millibar temperatures still in the 18 to 19 celsius range, it will continue to be rather hot, with temperatures similar to today's highs. As for convection, there is actually decent model agreement in keeping the bulk of the monsoonal moisture south of Wyoming. The main area of concern would be across southern Wyoming, but even here chances look fairly small, generally less than a 1 out of 4 chance. I can't rule one out in some of the normal development areas, like the Washakie Needles at the southern end of the Absarokas, but with the chance less than 1 out of 6 we kept the forecast dry for now. As for fire weather concerns, there could still be some. Relative humidity will still be in the teens but a bit higher than over the weekend. Wind also looks borderline. So, we will not extend the warnings at this time, but future shifts may want to take another look at things.

The pattern begins to shift on Wednesday. A weak cold front will approach from the northeast and bring cooler temperatures starting on Wednesday but especially for the end of the week, with below normal temperatures for many from Thursday into next week. And, moisture will increase starting on Wednesday. This will bring an increased chance of showers and thunderstorms across the area into the weekend. Precipitable waters look to rise above 150 percent of normal starting especially on Thursday and continue into the weekend. At this point, it does not look as moist as during the middle of July, with precipitable waters maxing out at around 25 percent less than that time period. As for details, they are still uncertain. The monsoon will be enhanced by a few shortwaves passing through but these are difficult to time, especially toward the end of the week. There is some agreement with most activity bring East of the Divide on Wednesday, past that time details become far more uncertain in regards to placement and day of most numerous activity. As for possibly heavy rain and flooding, there is one difference. Mid level flow will be somewhat stronger than a few weeks ago, with 20 to 35 knots of flow at 500 millibars. This should allow storms to have more movement and reduce the risk somewhat. This, along with fact that the recent dry weather means there is plenty of room in the soil. However, we do need the rain and we will take what we can get, as long it is not too much all at once.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 408 AM MDT Sun Aug 9 2026

Largely VFR conditions should continue through 12Z Monday. The main concern continues to be areas of smoke that will continue across the area, especially in the northern half of Wyoming. Visibility should remain above 6 miles for the most part. However, brief periods of MVFR visibility remain possible at all terminals. Confidence remains to low to time the thicker smoke and lower visibility. There is around a 15 percent chance of an afternoon shower in vicinity of all TAF sites with the exception of KJAC, KWRL and KCOD this afternoon. With the less than 20 percent chance, we left mentions out of the TAF forecast for now. The exception is in vicinity of KRKS, where the PROB30 group was continued. The only threat would be wind gusts over 40 mph with the very dry conditions at the surface preventing rain from reaching the ground. Most showers should end after 03Z. Breezy conditions develop at all TAF sites after 18Z with gusts to 15 to 25 knots possible at most. Wind decreases after sunset tonight as the atmosphere decouples.

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 1256 AM MDT Sun Aug 9 2026

Today will be similar to Saturday. A combination of hot temperatures, humidity falling to around and under 10 percent and a gusty afternoon breeze will bring elevated to critical fire weather to most of western and central Wyoming, especially in the afternoon. Isolated showers and thunderstorms in central and southern Wyoming will bring little rain, but could bring wind gusts over 40 mph and possible lightning strikes. Hot weather continues Monday and Tuesday although somewhat higher humidity may ease fire weather concerns somewhat.

RIW WATCHES/WARNINGS/ADVISORIES

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

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