JACKSON, Wyo. — Persistent heavy smoke from wildfires in California has impacted visibility and air quality in Jackson Hole since last Thursday while conditions have remained hot and dry. However, if you’ve grown tired of the smoke and are ready for cooler temperatures, there are some hopeful signs within the next seven days.
Smoky Conditions to Continue Through Friday
On August 15, the remnants of tropical activity in the Pacific reached California, which combined with a potent upper atmospheric disturbance, triggered a round of widespread strong thunderstorms (a rarity in California) with minimal rains that ignited massive fires across California.
The sheer amount of smoke these fires have produced combined with persistent west/southwest winds aloft blowing in from California explain why the smoke has been so thick in Jackson Hole and across the Intermountain West.
Check out the visible satellite image from Monday morning, where areas of haze can easily be seen across much of the Western U.S. and even into the Great Plains.
The smoke is going to hang around in varying degrees over the upcoming week as we remain stuck in a west/southwest flow. We may see some minor improvement at times on Monday and Tuesday as the main smoke plume briefly attempts to lift north, but don’t expect clear skies.
However, there is a potential end in sight over the upcoming weekend. An approaching trough of low pressure will result in a wind shift to west/northwest flow aloft starting on Saturday and becoming even more pronounced on Sunday.
This wind shift should clear out the California wildfire smoke this weekend. The only question mark is whether or not we can avoid any new wildfire starts nearby or upstream of us in the meantime.
A Very Hot and Dry August — Will We Finally See Some Rain this Week?
So far, the weather station in Jackson has recorded only a trace of rainfall in August. Since 1905, there have been only two other years in which no measurable rain was recorded in Jackson during the month of August (however, there are several years with missing data).
Elsewhere in the valley, the Moose weather station has not recorded any rainfall this month and the Moran weather station has only recorded 0.01 inches of rain. If we don’t pick up any significant rainfall this week, then this August will go down as one of the driest on record in Jackson Hole.
Top 5 Driest Augusts in Jackson (records dating back to 1905):
- 0.00” – 1944
- 0.00” – 1934
- Trace – 2020* (through August 24)
- 0.01” – 1937
- 0.03” – 1924
Top 5 Driest Augusts in Moose (records dating back to 1959):
- 0.00” – 2020* (through August 24)
- 0.08” – 2002
- 0.16” – 1992
- 0.18” – 2016
- 0.21” – 1985
As dry as it’s been, we actually stand a decent chance of picking up some measurable rainfall in Jackson Hole this week (and more than just isolated “dry” thunderstorms).
Moisture from tropical activity in the Pacific is arriving from the southwest and will continue to increase on Tuesday and Wednesday with rising dewpoints in the valley. This pattern will lead to increasing thunderstorm chances with wetting rains possible on Tuesday and Wednesday. Stronger thunderstorms on Tuesday and Wednesday could produce isolated rain amounts of up to 0.25 inches.
Taking a look at the average of 22 short-range models, locations in Teton County are projected to pick up an average of 0.1-0.2 inches of rainfall through Thursday, with heavier amounts in the ranges east and north of Jackson.
These models are not high-resolution, and so this doesn’t account for terrain features or the hit-or-miss nature of thunderstorms that leads to locally higher or lower amounts. Even so, it paints a broad picture showing that there is a good chance that most areas will see at least some measurable rainfall this week.
Strong Cold Front Expected in About a Week From Now
Confidence is increasing that we’re going to see a taste of fall to begin next week after an extended stretch of above-average warmth.
Temperatures this week will start out in the upper 80s for highs on Monday before gradually trending cooler for the remainder of the week as high pressure weakens.
However, the big change will occur late on Sunday or early next Monday as a powerful cold front arrives from the north. The image below shows the model-projected colder than average airmass moving into Wyoming next Monday morning (August 31).
The main impacts will be a shift to well-below average temperatures early next week with a good chance of seeing freezing nighttime temperatures.
Overall, moisture looks limited with this front and the best chance of precipitation will be east of the Continental Divide in the Beartooth, Absaroka, and Wind River Mountains during the Sunday-Tuesday timeframe.
However, we could see some light showers reach the Tetons and Jackson Hole as well, and some high elevation snowflakes couldn’t be ruled out either (fair warning to anyone planning to hike the Teton Crest Trail or climb the Grand early next week!).
Alan Smith, Meteorologist
