Jackson Hole Weather July 12-18, 2022

JACKSON, Wyo. — Hot temperatures and increasing thunderstorm potential can be expected over the next week as a ridge of high pressure strengthens over the Central Rockies. At the same time, a surge of monsoonal moisture will arrive from the southwest mid-week, which combined with frequent upper air disturbances will result in near daily rounds of thunderstorms from Wednesday through Monday.

July 5-11 Recap

Over the past week, we have experienced a quiet summer pattern with above average temperatures along with dry and sunny conditions. No rain fell in the Tetons or Jackson Hole Valley over the past 7 days with storm activity confined to areas east of the Continental Divide and north of the Montana border.

High temperatures over the past week ranged from 82ºF on July 5 to 89ºF on July 9 and low temperatures ranged from 35ºF on July 5 to 43ºF on July 7.

Forecast for Tuesday (7/12) to Monday (7/18)

A more active pattern is set to take hold this week as monsoonal moisture arrives from the south. That means near daily rounds of thunderstorms across the higher terrain in particular, so plan accordingly if you’ll be out hiking, climbing, camping, etc., especially after the past 7-10 days of dry weather.

Despite the uptick in rain and thunderstorm chances, we will also be dealing with continued well above average temperatures. High temperatures each day will be somewhat dependent on cloud cover and the timing/extent of thunderstorms, but in general, we will see highs ranging from the mid 80s to low 90s in the valley.

The arrival of monsoonal moisture will also mean more cloud cover overnight and warmer nights compared to what we’ve seen recently, which will be a downside for home cooling purposes.

Getting into the day-to-day details, Tuesday will be the final day of our recent dry and sunny pattern with no thunderstorm chances. Temperatures will also heat up with highs reaching the upper 80s to near 90 in the valley.

On Wednesday, monsoonal moisture will begin to filter in during the morning hours with thunderstorm chances beginning by midday and increasing throughout the afternoon and evening hours. An upper air disturbance will also arrive on Wednesday afternoon, which will help to trigger thunderstorm development.

The one thing we’ll have to watch for is possible overcast cloud cover on Wednesday morning – if this occurs, it could delay surface heating and thunderstorm development until later in the afternoon. However, if there is abundant sunshine early on then thunderstorms will be possible by midday, if not sooner.

With ample moisture arriving on Wednesday, some storms could be on the stronger side with frequent lightning, gusty winds, hail and locally heavy rain possible. Storms will be relatively fast-moving from west/southwest to east/northeast.

There is also a slight chance of showers/thunderstorms during the overnight hours on Wednesday night as well as on Thursday morning, so keep this in mind if you are planning to camp.

On Thursday and Friday, monsoon moisture will be well established and scattered thunderstorms are expected both days as a result. Most of the thunderstorm activity will occur during the afternoon and early evening hours, but there is also a slight chance of overnight/morning activity on Thursday night and Friday morning.

Storms on Thursday and Friday will also track from west/southwest to east/northeast and will be a little slower-moving compared to Wednesday. Once again, frequent lightning, gusty winds, hail and locally heavy rain will be possible.

Thursday should be a more active day compared to Friday, whereas Friday could go either way. We’ll have moisture and instability to work with on Friday but will also be fighting warmer air arriving in the mid-levels of the atmosphere that could potentially result in a stable layer that suppresses storm development.

On Friday night and Saturday, drier air will move in temporarily, reducing the threat of thunderstorms on Saturday afternoon. A few isolated storms couldn’t be ruled out at this time, but if you’re looking for a better climbing weather window then Saturday may be a better bet.

Temperatures are also likely to heat up more on Saturday with increasing sunshine, with highs reaching gate low 90s in the valley.

The next surge of monsoonal moisture is projected to arrive on Sunday, and thunderstorm chances will increase again on Sunday and Monday as a result. Temperatures should moderate slightly with more cloud cover, but still remain very warm by our standards.

Another subtle feature to keep an eye on this week is for some haziness in the skies from time to time. This will be the result of light smoke arriving from wildfires in Utah and California. Heavy smoke and significant air quality concerns are not anticipated at this time, provided there are no new fire starts closer by to our west.

As far as fire danger goes, we are currently listed in the “Moderate” category in terms of vegetation fuels. The consistent above average heat is not helping matters, and we could see quite a bit of lightning this week, but on the plus side, abundant monsoonal moisture should result in a higher proportion of wet versus dry thunderstorms and relative humidity will remain above critical levels.

Extended Outlook

A trough of low pressure will move across the Northern Rockies early next week, and this will eventually push the monsoonal moisture out of the area by around next Tuesday (7/19). Once this occurs, we will transition back into a drier pattern for most of next week, with temperatures continuing to run well above average.

It’s possible we could see the northern fringe of monsoonal moisture (centered over the Southwest U.S.) extend far enough north at times to result in isolated thunderstorm chances, mainly of the dry variety (i.e. more lightning and wind than rain). But for the most part, next week is simply looking hot and dry.

Alan Smith, Meteorologist