textproduct: Western and Central Wyoming

KEY MESSAGES

- Remaining warm today with an increased chance (as high as a 2 out of 5 chance) of a shower or thunderstorm today.

- Remaining warm on Memorial Day with further chances of a shower or thunderstorm, especially along and West of the Divide.

- Much of next week will have daily chances of showers and thunderstorms, although placement of the most numerous storms and best chance of heavier rain remains rather uncertain.

DISCUSSION

Issued at 100 AM MDT Sun May 24 2026

As with most things with forecasting the weather, there are some things we know, and some things we don't know. And, there is no exception to this as I write this early on Sunday morning. I am listening to hair metal this morning, and the song Dirty Love just came on. And this ties into the main hazard over the next several days. The above mentioned song is by a British hard rock band called Thunder (they were a thing for a brief time in the early 90s). We will have daily chances of thunder for the next several days. That is the part we know. The part we don't know, especially a few days out, are the coverage and placement of the storms.

We currently have a few showers out there, largely in southwestern Wyoming. Little if any of the precipitation is reaching the ground though. The main driver of the thunder today will be a shortwave moving in from the west and some increasing moisture from the southwest. This should increase coverage of showers and storms this afternoon and evening. There is good model agreement of having the highest coverage (about a 2 in 5 chance) across the southwest with tapering chances further to the north and east. Precipitable water values are about 50 percent higher than yesterday. However, model soundings continue to show Inverted Vs along with high cloud bases. Dew point depressions are also over 40 degrees in many locations once again. What this means is that although there is a better chance for some rain to reach the ground, there will still be a lot of virga showers and possibly dry thunderstorms. And this means that we have the potential of strong wind gusts from any shower or thunderstorm. Most convection again looks diurnal and should decrease after sunset.

Memorial Day may end up being a bit drier than today, as heights rise by around 40 decameters and precipitable water values fall by around 25 percent. Most guidance is fairly consistent with this. Most guidance is also in decent agreement in most of the showers and storms remaining West of the Divide with less than a 1 out of 5 chance East of the Divide. With the southwest flow, temperatures should average 5 to 10 degrees above normal through the holiday weekend.

The uncertainty really increases as we head into Tuesday and the rest of the week. And what happens is dependent on the position of two features. One, is a strong ridge that will be found across the midwest. The second, which has more impact on us, is one of the features that leads many meteorologists to early hair loss. It is a stacked upper level low that will move onshore in the Pacific Northwest Monday night and Tuesday and drift toward the Great Basin for the middle of the week. If looks like it will cut off from the main low and sit for a few days, but exactly where will be the determining factor for our weather. Ensemble guidance is all over the place. With the deterministic models, the GFS, which has been flip-flopping more than a fish out of water, now keeps the low west of Wyoming before opening it up into a trough for the end of the week. The European model has been more consistent, keeping the low a but further south during the middle of the week before moving it northward about 24 hours later, again West of Wyoming. As for the forecast, the low will continue to feed moisture into the area, and as a result there should be some showers and thunderstorms around each day. However, the moisture may be more of the mid and high level variety. Model soundings at this time show largely inverted Vs which would imply more high based showers and storms. But a lot depends on the ultimate path of the low, and cut off lows are one of the most difficult things to forecast. If it moves further east, we have a better chance of some still needed rain. And as far as placement and timing of the showers and storms, a lot depends on shortwaves rotating around it and these are difficult to time this far out. For now, we kept the forecast largely broadbrushed with more POPs in the mountains and western Wyoming and precipitation largely diurnal. Temperatures look to be near to slightly above normal through the period.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 418 AM MDT Sun May 24 2026

Largely VFR conditions are expected through the TAF period. A few showers are moving into the western mountains at this time, so we added VCSH in vicinity of KJAC until around 15Z. Increased instability will lead to scattered showers and isolated thunderstorms this afternoon, with the greatest coverage in southwestern Wyoming. With increases in instability across the western mountains, we also added a PROB30 group for KJAC starting at 19Z. A few locations may see a thunderstorm, but with chances generally less than 20 percent, not enough confidence for a PROB30 group. Breezy conditions are possible this afternoon with gusts to around 20 to 25 knots in the normally windier sites. Wind gusts to 35 to 40 knots will be possible around any shower or thunderstorm. Most activity should end after 03Z tonight as the sun sets and instability decreases.

RIW WATCHES/WARNINGS/ADVISORIES

None.