textproduct: Western and Central Wyoming

KEY MESSAGES

- A combination of low humidity, a gusty wind and unseasonably warm temperatures will bring near critical to critical fire weather conditions to much of the area this afternoon.

- Continued dry conditions and fire weather concerns for Friday and Saturday for point north of Fremont to Natrona Counties.

- The next decent chance of showers continues to be late Sunday with the next surge of monsoonal moisture and especially into early next week being more widespread.

UPDATE

Issued at 1200 PM MDT Thu Sep 3 2026

Dry conditions continue to be on the agenda for the remainder of today and into Friday. Little change to the short term forecast, outside of Red Flag Warnings extended through Friday afternoon and evening but limited to points north of Fremont to Natrona Counties. It won't be as dry humidity wise further west and south with a bit of moisture pushing northward from the south. This will come into full fruition come late Sunday and into early next week with the next system coming in to collision with the monsoonal moisture.

DISCUSSION

Issued at 227 AM MDT Thu Sep 3 2026

Another night of nocturnal monsoonal convection is on going again tonight across portions of the area. And like, previous nights, the models have had no clue about it. This year performance of the guidance for the monsoon, has been in a word, bad, especially in weakly forced situations and at night. What I wouldn't give for a nice, strong Canadian cold front to sweep across the area and drive the monsoon out of here until next summer. I think it is hanging around just to spite me. These showers should be ending by sunrise, I hope.

There is a sign though. It is that to the west, there is no convection, drier air is over there. Model guidance is in good agreement with bringing much drier air moving eastward into the area, with precipitable water values falling under a half an inch in all areas. This should shut off the convection. However, we will have another concern to replace it. We have roughly the same set up as yesterday, with a fast flow over the area and the jet stream nearby and 700 millibar winds as high as 35 to 40 knots. This will bring a gusty wind to most of the area. The NBM ensemble gives at least a 1 in 2 chance of gusts past 25 mph across most of the area. With humidity expected to be dropping to under 15 percent across much of the area, critical fire weather has a high probability (greater than 2 out of 3 across most locations). So, we will continue the Red Flag Warning as is for now. And it will be another of above normal temperatures, with the warmer spots like the eastern Bighorn Basin getting close to 90 degrees.

Fore weather concerns look to continue into Friday as well. The main difference is that dew points may begin to recover somewhat, especially across southern Wyoming, so things look more borderline tomorrow. There will still be plenty of wind though, with a similar area having a greater than 1 in 2 chance of wind gusts over 25 mph. I could see extended the Red Flag Warning another day but it would be more a more limited area, likely limited to East of the Divide. Otherwise, it looks like another dry and warm day, possibly a bit warmer than today, with some locations seeing highs over 90 as ridging over the southeastern United States retrogrades back to the west.

We should begin to see fire weather conditions improve on Saturday as humidity begins to rise somewhat and wind begins to decrease. There could still be some elevated fire weather in portions of the area though. Then on Sunday, the next surge of monsoonal moisture arrives, finding a path between an upper level low to the west, the ridge of high pressure over the southern Plains and some moisture from Tropical Storm Marie in the eastern Pacific. Lift may also be enhanced by a Pacific Cold Front and negatively tilted trough moving in from the west. Precipitable water values generally top out at around 150 percent of normal, as much as an inch in our eastern counties. At this point, the threat of flooding looks small since most guidance is indicating a decent amount of low and mid level flow, indicating the storms will be moving and not stationary. Location of the heaviest and most numerous showers and storms is still in question though, with still a decent spread in model guidance in this regard. There is more uncertainty following this. Some guidance brings in drier air behind the front, other guidance keeps some monsoonal moisture over the area. Temperatures will likely be a bit cooler behind the front, but likely only falling back to near normal levels.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1128 AM MDT Thu Sep 3 2026

Isolated mid to high level clouds will continue to pass across far western and northern Wyoming before clearing through the afternoon. Gusty winds up to 25 to 30 kts will develop and persist through sunset, with KRKS holding on to gusts a bit longer into the overnight hours. Isolated mid level clouds will develop overnight for most areas as well before clearing out after sunrise and through 00z Friday. Then a return to gusty winds 25 to 30 kts after 15z Friday, hanging on for all terminals through the 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 227 AM MDT Thu Sep 3 2026

A combination of humidity falling under 15 percent,a gusty wind and warm temperatures will bring elevated to critical fire weather to most of western and central Wyoming this afternoon and evening. Elevated to possibly critical fire weather will be possible again Friday afternoon, especially East of the Continental Divide. Conditions should improve somewhat on Saturday with somewhat higher humidity and especially Sunday when the chance of showers returns.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM MDT this evening for WYZ275>283- 285>289-300.

Red Flag Warning from noon to 9 PM MDT Friday for WYZ275-276- 280>283-285>287-289.