textproduct: Western and Central Wyoming

KEY MESSAGES

- Hot, dry, and breezy conditions continue through Tuesday. This will lead to continued near-critical to critical fire weather conditions. RFW's remain in effect through 9 PM today.

- Scattered rain showers and isolated thunderstorms will develop across southern portions of the area this afternoon as well as Monday afternoon. Most showers will remain virga with gusty downdraft/outflow wind of 40-55 mph the main hazard.

- Wildfire smoke continues to stream into the area early this week leading to reduced visibility and poor air quality. Air Quality Alerts remain in effect through noon tomorrow.

- A welcome pattern change appears likely (70%) late this week as moisture brings better chances for rain and much cooler temperatures.

UPDATE

Issued at 1121 AM MDT Sun Aug 9 2026

The first storm of the day has developed in southwest Sweetwater County in the past half hour. More isolated storms and scattered rain showers will develop across southern Wyoming this afternoon. Most rain showers will remain virga and very little rain will reach the ground with the strongest showers/storms. It should be no surprise that the main hazard today will be strong downdraft/outflow wind from showers and storms. The Red Flag Warnings remain in place through 9 PM this evening as the combination of hot temperatures, very low humidity, and breezy wind leads to critical fire weather conditions. More Red Flag Warnings may be needed for some zones Monday and Tuesday, but for now did not issue due to current RFWs in effect. It seems that model guidance is coming into better agreement on good moisture moving into the area late this week with much better chances for actual rain in the area. Still trying to hammer down the details at this time.

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 /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1100 AM MDT Sun Aug 9 2026

VFR condition should prevail through the period. However, with wildfire smoke over the area, visibilities could drop to around 5SM or 6SM at times. Smoke may see slight improvement toward the very end of the period, especially across southern Wyoming. For today, virga or light showers, and possibly an isolated thunderstorm, is possible for southern Wyoming. Confidence is not high in any site getting impacted, though KRKS would be the most likely. The northern extent of chances stops around KPNA and KRIW. Outflow gusts around 40 knots are possible with any shower or storm that does occur, though an isolated gust to 60 knots cannot be ruled out around KRKS.

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 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.