textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers and thunderstorms will be around today but less numerous than on Tuesday (around a 1 in 4 chance). Otherwise remaining warm with a gusty wind, especially in northern Wyoming.

- The chance of thunderstorms reaches a minimum on Thursday with only isolated storms (less than a 1 in 5 chance) in and near the mountains.

- A weather system approaches the area on Friday night and Saturday and brings a better chance of showers, with the greatest chance across western Wyoming.

DISCUSSION

Issued at 1254 AM MDT Wed May 27 2026

I am thinking of another childhood memory has I was composing the forecast tonight. One of the traditions of being home sick from school in the pre-internet age was watching daytime TV. And one of the most popular shows was (and still is), the Price Is Right. And our weather pattern this morning remains me of one of the games on that venerable game show, Squeeze Play. It relates to the weather is we are trapped between the cut off upper level low rotating near the Sierra Nevada's and a strong ridge to the east.

For today, it is showing off with our precipitable water values. They are projected to be above normal as much as 150 percent in some locations East of the Divide. Meanwhile, areas West of the Divide are below normal. This would imply the greater chance of convection shifts here today. But, there are a couple more factors. Instability is less, as heights have risen by around 50 decameters. There is also only half as much projected CAPE as yesterday (350 J/Kg today versus 700 J/Kg yesterday, so coverage may be less. The lasting thing we look at is the mean flow, and that is largely south- southeast with the squeeze play between the low and the ridge. This leads me to think that the best chance of convection would be close to areas where this flow is upslope. This means locations like along and east of the Absarokas and the Big Horns, for places like Park. Johnson and Natrona County as well as portions of the Wind River Basin and Yellowstone Park. But given the more limited instability, coverage looks less, generally less than 1 out of 4 or less. An the squeeze play will have one more impact, the wind. There is a decent pressure gradient in the eastern portions of the area. The NBM ensemble is showing a greater than 2 in 3 chance of wind gusts past 30 mph in the Bighorn Basin and Johnson County. The strongest wind would be in Johnson County, where there is 1 in 2 chance of gusts around 40 mph this afternoon as we reaching peak mixing. Temperatures should be similar to yesterday, about 5 to 10 degrees above normal but no extremely hot conditions. Most convection looks diurnal today, with most showers and storms ending after sunset.

At this time, convection looks to reach a nadir on Thursday, as drier air surges further eastward across the state, with the 0.50 inch precipitable water line enveloping most of western and central Wyoming. Any convection this day would likely remain close to the mountains with high level heat source and upslope flow, mainly of the south to southeastern variety again. The vast majority of locations, especially in the lower elevations, should remain rain free. Wind should also be lighter except for Johnson County, where a gusty wind will continue. High temperatures should run near to a couple of degrees warmer than Wednesday.

Chances of showers should begin to rise somewhat on Friday as the cut off low begins to get kicked eastward by the next trough approaching the west coast. The atmosphere will be very dry to start though, so this could end up being a later show. Placement is also uncertain as a lot depends on how quickly deeper moisture can be advected into the area. The current forecast looks like a reasonable compromise, although most of the day should be rain free.

There is now decent agreement in the low opening up a bit and lifting northward Friday night and moving into western Wyoming on Saturday. This looks like the wettest day as a result. The exact path of the low will be critical though. If it tracks further west, many areas East of the Divide may have a southwesterly downsloping flow which would keep showers and thunderstorms to a minimum. The current forecast has this shown fairly well, with the highest POPs in the northwest then tapering them down the further south and east you go.

Then more uncertainty creeps into the forecast for Sunday and early next week. Some models and ensemble members show the low cutting off again and lingering near the area into early next week, keeping the forecast cooler and unsettled. Others lift it out and bring a southwest flow which would bring warmer weather and mainly chances of diurnal convection. It is a coin flip which one will win out at this time though.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 417 AM MDT Wed May 27 2026

Largely VFR conditions should continue through 12Z for the most part. Moisture will continue to feed into the area from the south today but the main chance of storms shifts largely East of the Divide today. We continued the PROB30 group for thunderstorms in Casper. We also added a PROB30 Cody where southeasterly upslope flow may bring some afternoon and evening convection as well. Elsewhere, the chance is less than 20 percent so we kept it out of the TAFs for now. There is a 20 percent chance of brief MVFR conditions with any shower or thunderstorm.

Gusty wind will also continue today. The strongest wind will be found across northern Wyoming, where gusts over 25 knots will be possible in vicinity of KWRL. Many other terminals could see gusts between 15 and 25 knots after 18Z before wind begins to decrease after sunset.

RIW WATCHES/WARNINGS/ADVISORIES

None.