textproduct: Western and Central Wyoming

KEY MESSAGES

- Another warm day with another round of scattered showers and thunderstorms (up to a 2 and 5 chance), mainly in the afternoon and evening. The best chance will be East of the Continental Divide.

- Thunderstorms chances trend down and temperatures trend upward starting Thursday and especially this weekend.

- The hottest weather over the year and potentially in some time arrives this weekend, with some all time record high temperatures possible. The best chance all time record high temperatures will be on Sunday afternoon.

DISCUSSION

Issued at 245 AM MDT Wed Jul 8 2026

I have a question for you this morning. What do these things have in common: gas pressure and volume, supply and demand and speed and travel time. If you answered inverse relationships, you would be right. And that is what we will have over the next week, as the temperature goes up, the chance of convection goes down.

Today will be somewhat similar to yesterday. Another shortwave will be moving through the area. We also continue to have fairy steep low and mid level lapse rates. Instability values are also decent, with some portions of the area (mainly the northeastern portions of the area) having over 1000 J/Kg of CAPE and lifted indices as low as minus 5. There will be one difference though, and this will be a trend over the next few days. And that is that precipitable water values are a lower than yesterday, especially West of the Divide. But even East of the Divide, values are 10 to 20 percent lower. It is still around 130 percent of normal though. As a result, it will be another day anywhere from a 1 in 5 to 2 out of 5 chance of a shower or thunderstorm, with the best chance in the afternoon and evening and across northern and far southern Wyoming. The lowest chance will be across the west with less than a 1 in 10 chance. Temperatures will be similar to yesterday, near to somewhat above normal. As for any stronger storms, the best chance would be over Johnson County where there is a marginal risk, with strong wind gusts and marginally severe hail the main threats. Strong wind gusts will be a threat with any shower or thunderstorm though, even further west where dew point depressions will be larger.

The downward trend in convection continues on Thursday as drier works a little further east. There will still be some convection around, but most would be confined to East of the Divide again and especially in Johnson and Natrona Counties where the deepest moisture will remain. Temperatures look largely similar to today.

The inverse relationship really begins on Friday as ridging over the desert southwest begins to push northward with rising heights and temperatures aloft. This is the day when below normal precipitable waters will push across the entire area. We can't rule out a stray shower or thunderstorm, mainly over the northern mountains, but even here the chance is less than 1 out of 5. Temperatures will also begin to really rise, with the normally warmer spots seeing high temperatures approaching 100.

It is Saturday when we really begin to throw some coal into the blast furnace, otherwise known as a death ridge. Heights across the area will climb to over 5950 meters at 500 millibars, and bring definitely the hottest weather of the year. The NBM ensemble gives a greater than 1 out of 2 chance of high temperatures above 100 degrees in locations 5200 feet or below, with a nearly 100 percent chance in the warmer spots likely from Thermopolis up to Greybull. All locations below 6500 feet have a 4 out of 5 chance of temperatures over 90 degrees. Some records will likely fall on this day. With the dry air in place and warm temperatures aloft, the chance of convection looks just about nil.

However, the heat looks to peak on Monday. This mornings guidance shows 700 millibar temperatures climbing as high as 24 degrees celsius. This combined with nearly full sunshine will lead to one of the hottest days in quite a while. Ensemble guidance shows a nearly 100 percent chance of high temperatures over 100 degrees below 5500 feet, and places like Rock Springs, Green River and even Jackson have a greater than 1 out 3 chance of high temperatures over 100 degrees. When we go up to 105 degrees, ensemble guidance gives a greater than 4 out of 5 chance of this from Thermopolis to Greybull, with Riverton even having a 1 out of 2 chance. And going up even further, to 110, there is a 2 out of 5 chance a place like Greybull or Worland could reach this temperature. We could see some all time high temperatures fall on this day as the 5980 500 millibar ridge will be centered just about over Wyoming.

We should begin to take a couple of degrees off of the highs on Monday as the ridge retreats to the east just a bit. However, most areas below 5500 feet will again have at least a 1 in 2 chance of high temperatures above 100 degrees. And with the ridge moving East, some moisture, mainly of the mid level variety will begin to come around the back side of the ridge. A couple of storms are possible on Monday, but chances increase more on Tuesday and into Wednesday. With the low levels remaining rather dry, these thunderstorms would produce more wind than rain though. Convection should be on the isolated side though with most locations not seeing one on any given day. Temperatures will drop somewhat from the blast furnace levels of the weekend, but look to remain above normal through the middle of next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1058 PM MDT Tue Jul 7 2026

Prevailing VFR conditions through the TAF period. Isolated to scattered showers and thunderstorms will develop Wednesday afternoon. Coverage will be less than Tuesday afternoon. Western terminals (KJAC, KBPI, KPNA) should miss out on most of the convection Wednesday afternoon and evening, although there is still a low chance (around 10-15%). Most terminals have PROB30 groups for -TSRA and strong VRB wind. Conditions may drop as low as IFR in the strongest storms if they move directly over a terminal. Isolated rain showers will move through southern portions of the area, with some showers in the vicinity of KRKS overnight and early Wednesday morning.

Wind will be light tonight into Wednesday morning. Wind should become breezy (10-15 knots) Wednesday afternoon, but will be quite VRB due to numerous outflow boundaries from showers and storms. Isolated wind gusts to 50 knots are possible with the strongest storms Wednesday afternoon.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.