JACKSON, Wyo. – Scattered thunderstorms on Thursday and Friday will give way to more widespread, soaking rainfall this weekend. Highs will struggle to get out of the 50s in the valley on Saturday and Sunday, and snow could accumulate down to 9,000 feet or lower on Sunday.
Recent Weather
Early summer conditions have prevailed over the past week with warm temperatures and mostly quiet weather.
The one exception was on Saturday when a shortwave trough moved through, triggering scattered showers and thunderstorms. However, the activity was a bit less than originally expected, with rain amounts ranging from 0.03 to 0.34 inches across the area.
The highest rain amounts from this event were recorded around Jackson Hole Mountain Resort and around Moran Junction. The town of Jackson only received 0.03 inches of rain.
Seasonally warm temperatures prevailed on Sunday and Monday with highs in the mid to upper 70s, while highs have reached the 80s on Tuesday and Wednesday.
Here is the 7-day weather summary for the town of Jackson:
For perspective, the average high and low temperatures in Jackson on June 24 are 76º and 42º.
Upcoming Weather Pattern
June has been a very dry month overall, but some much-needed moisture and cooler temperatures are heading our way this weekend. The culprit will be a very powerful low pressure system (for this time of year) that will arrive from the northwest.
First, a shortwave trough will move into our area out ahead of this main system on Thursday. This shortwave will pull in monsoonal moisture from the southwest, resulting in an active day with showers and thunderstorms expected.
The highest threat of thunderstorms actually looks to be during the morning hours, with the main window from roughly early morning through early afternoon, rather than the usual mid-afternoon thunderstorm window. Heads up if you have morning outdoor plans.
Thunderstorms on Thursday will produce hit-or-miss rainfall depending on the track and strength of individual cells, but moisture levels will be sufficient for locally heavy rain to occur beneath these storms.
A break in the pattern is likely from Thursday evening through Friday morning, then another round of scattered thunderstorms is possible on Friday afternoon as the main storm system approaches.
More widespread rain showers are likely throughout the day on Saturday, possibly starting early in the morning, and a significant cool-down is also expected with highs in the upper 50s to low 60s. Be prepared for cool and wet conditions if you plan on spending time outdoors.
Sunday looks like another cool and wet day, though showers are expected to be more intermittent compared to Saturday.
Snow levels will drop as low as 8,000 to 9,000 feet on Sunday morning, with light snow accumulations expected at the 9,000 to 10,500 foot level, with heavy/wet snow accumulations possible above 10,500 feet.
This is your annual reminder that it can snow at any time of year in the Tetons.
On Monday and Tuesday, confidence in the pattern is lower, but there are some hints of a secondary low-pressure trough, which will give us at least a chance of more showers along with continued below-average temperatures (though starting to warm up from Sunday’s levels).
Total precipitation through June 30 will generally range from 0.8 to 1.6 inches in the Tetons and 0.6 to 1.2 inches in the valleys, with isolated higher amounts possible depending on thunderstorm behavior.
Here is a projection from the European (ECMWF) Weather Model (image source: WeatherFront):
While the wet pattern ahead is good news for our local fire danger, there is a chance we could see some smoke drift into our area from Utah wildfires on Friday. This would likely be temporary before the approaching low pressure trough scours out any smoke by Saturday, but it is still something to keep an eye on.
Looking further out, we should see a warming and drying trend during the first few days of July, leading up to the Fourth, with highs eventually getting back into the 80s. Longer range models are hinting at monsoonal moisture approaching our area from the south sometime after the Fourth, but confidence is low this far out.
Alan Smith, Meteorologist
