JACKSON, Wyo. – An unsettled weather pattern with slightly cooler temperatures is expected for at least the next week with intermittent showers and thunderstorms. But no significant, long-duration precipitation events or major cold fronts are expected.
Recent Weather Conditions
Over the past week, we have experienced slightly unsettled weather with a few rounds of showers along with a gradual cooling trend in temperatures.
Heavy wildfire smoke from Canada and Washington also impacted our area late last week, but fortunately, that has cleared out as southwest winds have pushed this smoke well north of our area.
Scattered showers and thunderstorms developed across the area on Saturday, Sunday, and Tuesday, but rainfall amounts have been very hit-or-miss.
The town of Jackson only received 0.11 inches of rain over the past week (and for the month of September so far), most of which occurred on Tuesday, while the upper portion of Jackson Hole Mountain Resort has received as much as 0.64 inches of rain.
High temperatures reached the 80s during the first few days of September in Jackson, but have been in the 70s since last Friday. The average high for September 10 is 75º for perspective, and average highs are quickly decreasing at this time of year.
We have had several chilly mornings with lows well into the 30s, but have not quite dipped below freezing yet this month in town. We have only had one freeze so far since the beginning of August, which occurred way back on August 10.
Upcoming Weather Pattern
The weather pattern for at least the next week reminds me more of what we expect in May than what we typically see in September. During May, it’s common to go through long stretches with daily rounds of showers, even if we don’t see any major weather systems (though that can certainly happen in May as well).
In September, we tend to have fewer days of rain with frequent dry and sunny stretches, but often we see heavier and more widespread rain from individual weather systems when it does rain.
That’s not the case this year, though. Instead, we have a very slow-moving low pressure system moving across the West this week with enough moisture, energy, and instability for daily rounds of showers and thunderstorms from Thursday to Saturday.
Most areas will see relatively light rainfall amounts on any given day, but locally heavy downpours are possible with any thunderstorms that develop.
Also, showers are possible at any time, day or night, but the best chance of showers and the highest coverage of showers will generally be in the afternoon hours.
On Sunday, we might see a break, but it’s not a sure thing yet. We will be in between low pressure systems, but some models have the next system arriving quickly enough for a chance of showers by Sunday afternoon.
As this system approaches, additional intermittent showers can be expected during the first half of next week. Again, heavy and widespread rainfall is not expected. Rather, the pattern will favor occasional showers with generally light amounts, except for locally heavy downpours underneath thunderstorms.
In other words, many outdoor activities can still be enjoyed in this upcoming weather pattern, as there are not any total washouts expected, and some sunny breaks in the cloud cover should also occur.
But be sure to pack rain gear and warm layers (it is fall now), and also be prepared for the possibility of lightning in the afternoon, and be ready to adjust your plans accordingly.
In terms of temperature, it will cool off a bit and will feel chilly at times, but no major cold fronts are expected like we can sometimes see at this time of year.
Highs in the valley will generally reach the upper 60s to low 70s each day, depending on afternoon cloud cover, and lows will be in the 30s to 40s.
Average snow levels will be around 11,000 feet, so the higher peaks of the Tetons will get dusted with snow in this pattern as showers move through. As a result, climbing conditions on the higher peaks will be less than ideal, with icy conditions likely, especially on more shaded routes.
Looking further out (beyond September 17th), confidence in the pattern decreases, but longer-range models are hinting at more of the same with additional weak disturbances possible that could bring showers, while there are also no signs yet of any major weather systems or big fall cold fronts.
Alan Smith, Meteorologist
