textproduct: Western and Central Wyoming

KEY MESSAGES

- Dry conditions reign across the region this Independence Day. - Daytime highs warm Sunday with only a few showers or perhaps a thunderstorm over northwest mountains, mainly in the mountains.

- Hot temperatures, about 6 to 12 degrees above normal, early next week with an increasing chance of afternoon thunderstorms both Monday and Tuesday.

- Drying out late next week and still hot. Temperatures may be the hottest of the season late next week into next weekend.

UPDATE

Issued at 100 PM MDT Sat Jul 4 2026

A sunny sky across the forecast area this Independence Day with only mountain cumulus drifting eastward into the nearby foothills/basins. Towering cumulus over the Uinta Range will stay along or south of the Wyoming border. Therefore, dry conditions prevail Saturday afternoon through midday Sunday. A shortwave passing through the Canadian Rockies draws a bit more moisture northward across the northwest portion of the forecast area Sunday afternoon. Instability and mid-level moisture should be sufficient to generate some weak convection late Sunday across the northwest mountains. Sunday high temperatures rise slightly, climbing to 5 to 10 degrees above normal The passing shortwave does nudge a front, accompanied by little more than a north wind shift, through northern Wyoming Sunday evening.

DISCUSSION

Issued at 140 AM MDT Sat Jul 4 2026

Happy Birthday to the United States of America! It is very fitting as I am starting this discussion that "America" by Neil Diamond is playing on the radio. We are also having some natural fireworks right now in the form of the Northern Lights. It is up to a G3 as I write this around 1 am so you can see it with the naked eye if you let your eyes adjust.

All in all, the weather looks pretty good across the area for July Fourth. A shortwave ridge looks to have timed itself just about right. We will have upper level divergence in place over the area. And for the first time in a while, surface CAPE is just about nonexistent. There are a couple of thin areas over northern Johnson County, far southern Sweetwater County and a few of the mountain ranges but nothing more than 100 J/kg. Lifted indices are generally positive as well. Below normal precipitable waters (generally around 20 percent below normal) will also be over the area today. All this adds up to very small chances for showers and thunderstorms. I can't rule one out at the above mentioned locations this afternoon, but the chance is maybe 1 out of 20. Otherwise, it will be warm today. Not hot as a firecracker, but a few degrees warmer than yesterday, with many locations east of the Divide rising into the 90s. Dry conditions should continue through tonight and into Sunday morning as well.

We will turn the heat up on Sunday as flow turns southwesterly. This could be the first day of 100 degree temperatures in portions of the area. Ensemble guidance gives around a 2 in 5 chance in places like Greybull, Basin, Worland and Thermopolis for example. Temps in the middle to upper 90s will be fairly widespread east of the Divide though with 80s in the lower elevations west of the Divide. The chance of convection returns as well, but it is rather limited. There is good model consensus that most of the forcing will remain north of the state over Montana. We do have some small chances in northern Wyoming, but the chance is less than 1 out of 5. Most areas will see nothing. As for fire weather, with the hot temperatures and very low humidity (down to 10 percent or less for many east of the Divide), it will be elevated. However, wind should remain light to moderate, so critical fire weather is not expected.

The chance of convection increases for Monday and Tuesday as a couple of shortwaves pass near the area. There are still disagreements with how widespread the convection will be though. The official forecast leans more toward the ECMWF model which is wetter, but this would likely be the wettest it would be. Northern Wyoming would be more under the gun for Monday, with Tuesday being more active as somewhat deeper moisture moves into the area (precipitable water values may climb to 150 percent of normal). With more cloud cover, temperatures may be a bit cooler, especially on Tuesday with more widespread showers and storms.

Tuesday looks to be the peak in coverage of showers and storms. There will still be some around Wednesday, but less than on Tuesday. Following that, chances of precipitation will begin to decrease as the pattern flips from this week. For much this week, we have had troughing over the western United States with a very strong ridge over the eastern United States, bringing record heat. Indications are this will switch to a mean ridge over the western United States, and potentially a very strong one. Some guidance shows a 6000 meter ridge (at 500mb) centered over Wyoming late next weekend into early next week. It is still a long way off, but the NBM ensemble is giving a greater than 1 in 2 chance for high temperatures over 100 next weekend for areas east of the Divide below 5200 feet. Again, this is a long way off but we have to watch this. We are likely looking at the hottest weather over the year for late next week and next weekend, with little chance of storms as well. Mid July is typically the hottest time of year, and this will be no exception.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1045 AM MDT Sat Jul 4 2026

SKC skies across the area through the period, although a FEW CU will occur for several locations between 20Z and 04Z. Wind gusts up to 20kt will occur by 20Z at KRKS, KBPI/KPNA and KCOD, decreasing by 02Z. Winds will remain light (11kt or less) for all other terminals and through the rest of the TAF period.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.