textproduct: Western and Central Wyoming

KEY MESSAGES

- Another warm day with mainly afternoon and evening isolated showers and thunderstorms (generally less than a 1 in 4 chance). Any shower or storm could have strong wind gusts.

- Mainly dry and quite warm for Independence Day.

- Low humidity will bring elevated fire weather each afternoon, but wind is expected to remain light to moderate and below critical thresholds.

DISCUSSION

Issued at 221 AM MDT Fri Jul 3 2026

Things turned out out pretty close to what was expected yesterday, with scattered showers and thunderstorms along with some strong wind gusts (we had 56 mph at the Riverton airport), as well as 54 mph at Buffalo and 49 mph at Worland. Things are fairly quiet right now though.

It often said that a lot of things in the physical and mathematical sciences are governed by sine waves, and meteorology is one of them. The most prominent being Rossby waves (look it up if you are curious). And that is how the chances of convection will be over the next several days. We reached the peak of the wave the past couple of days. We are now on the way down with chances.

There will still be a few storms around today. However, parameters are not the most impressive. CAPE tops out at only 500 J/Kg and lifted indices only fall to minus 2. Precipitable water values are also generally near to somewhat below normal. However, we continue to have very steep lapse rates (approaching 9C/Km). In addition, a subtle, emphasis on subtle, shortwave will be moving through the area. Many areas will have a chance, mainly in western and northern Wyoming where the most instability will be found. Most places won't see one though, so chances at a vast majority of the area are less than 1 out of 5. We continue to have high based storms with inverted V model soundings and large dew point depressions (greater than 50 degrees in many locations). That means the most likely threat from any shower or thunderstorm would be strong wind gusts. This includes the dreaded "Little Green Blobs", innocent showers that produce wind gusts when they collapse. This looks to be an earlier show, with almost all convection over by sunset. The other risk is fire weather. Some locations will see relative humidity fall below 15 percent. However, wind is not expected to reach critical levels. Elevated fire weather is likely in many locations though. Temperatures should be within a few degrees of normal.

We will reach the trough of the sine wave on Independence Day. Shortwave ridging will be in place across the area, providing some subsidence. Dry air will be in place across the area, with precipitable water values below normal for all areas. This means a very small chance of convection. The one spot that could see a stray storm is southern Sweetwater County, where models are showing some meager CAPE (around 200 J/Kg). I can't rule out a storm here, but the chance is less than 1 out of 10. And this would mainly be south of Interstate 80 and near the Unitas, where there is little population. Temperatures also move up a few ticks this day, on average around 5 degrees above normal for most of the area, which means near or above 90 for many locations East of the Divide. So quite warm, but not as hot as a firecracker.

On Sunday we begin to climb the sine wave again, as chances for storms begin to increase. However, they are fairly small on this day. This will be mainly across the north but chances here are only 1 out of 5. The big story this day will be the heat. This could be the day one of major climate sites could reach triple digits. GFS MOS shows 100 for a high at Greybull and 99 at Worland. The NBM ensemble gives around a 2 out of 5 chance for this. Nevertheless, this will be a day of widespread 80s in the lower elevations West of the Divide and 90s East of the Divide. Humidity will remain very low on this as well (10 percent or below East of Divide). But once again, wind should remain light to moderate.

Chances increase for storms increase early in the week, probably reaching the peak of the sine wave on Tuesday as another deeper moves across the area. There are still some different solutions with this, with some guidance keeping most of the storms north and others bringing it further south. Nevertheless, Tuesday looks like the best chance for showers and storms for most of the area. Chances then begin to descent toward the trough as ridging builds across the western United States. There are indications of possible heat wave the end of next week, but still some uncertainty. So, this the story as we ride the rollercoaster of the sine wave of mid summer weather in western and central Wyoming.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 427 AM MDT Fri Jul 3 2026

VFR conditions are expected at all terminals through 12Z Saturday. A weak weather system will move through the area this afternoon and bring isolated showers and thunderstorms (a 15 to 20 percent chance) to the terminals in the northwestern portion of the CWA (KJAC, KBPI, KPNA, KCOD, KRIW and KLND). At the other terminals, the chance is less than 15 percent. The main threat from any shower or storm will be erratic wind gusts over 35 mph. Otherwise, afternoon breezes with gusts to 15 to 20 knots are expected at most terminals. Most storms will occur between 20Z Friday and 02Z Saturday with a rapid decrease in coverage after sunset Friday night.

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.