JACKSON, Wyo. – We are transitioning into an early fall weather pattern across Northwest Wyoming as warm days and chilly nights are becoming the norm. Showers and thunderstorms on Wednesday will give way to dry and sunny conditions by the weekend.
Recent Weather
Since Labor Day, “comfortable” and “slightly unsettled” would be the best way to describe the weather pattern. It has not been entirely dry and cloud-free, but we have certainly seen less rainfall lately compared to prior weeks.
Frequent minor disturbances have resulted in cloud build-ups and isolated showers most days, but very little rainfall has been measured over the past several days with most areas notching anywhere from a trace to a few hundredths of an inch.
Temperatures have been just about perfect with highs in the 70s and lows in the 30s. We still have not seen our first freeze in the Town of Jackson yet this year. The average first freeze is in late August, so we are a couple of weeks behind schedule.
At the same time, it’s becoming increasingly likely that we may have seen our 80-degree day of the year already. In fact, we have not hit 80ºF at all in the month of September, which if this holds, would be quite unusual.
So far, temperatures are running 1.7ºF above normal in the month of September overall. However, similar to August, high temperatures are running slightly below normal while low temperatures are running above normal.
Upcoming Weather Pattern
A low pressure system is moving across the Central Rockies on Wednesday, and this is resulting in unsettled weather conditions. We saw a few rounds of showers move through on Wednesday morning, while the early afternoon has featured more abundant sunshine.
Heading into late Wednesday afternoon and Wednesday evening, an uptick in showers and thunderstorms is expected in advance of an approaching cold front.
Snow levels will be fairly high through Wednesday evening, generally ranging from 11,000-12,500 feet.
On Thursday, we will start to dry out with just a slight chance of showers in Jackson Hole, while a better chance of showers will exist east of the Continental Divide in the Wind River and Absaroka Ranges.
High pressure will build over the region from Friday through Sunday, resulting in mostly sunny skies and dry conditions. It looks like a perfect weekend for being outdoors, so enjoy!
High temperatures will be in the upper 60s on Wednesday and Thursday, before warming up into the mid 70s from Friday through Sunday. As moisture starts to decrease, we will see chilly nights and mornings, and perhaps we’ll finally see our first freeze in Jackson.
Next week, the pattern will turn more unsettled as a low pressure system is projected to move into the Western U.S. around September 19-20 (roughly speaking).
The track of this system and associated impacts around Jackson Hole are uncertain at this time. But at the very least, there is a chance we could see showers and cooler temperatures around September 19-20, and perhaps some snow for the higher elevations.
Here is a 7-day precipitation projection, which mainly accounts for precipitation anticipated today (September 13) and early to mid-next week (September 19-20).
Extended Outlook
Following the potential weather system around September 19-20, longer-range models are hinting that we may start to dry out and warm back up toward the end of next week (September 21-24, roughly).
After that, there are some hints the pattern could turn more unsettled again heading into the week of September 25, but confidence is low this far out.
Alan Smith, Meteorologist
