JACKSON, Wyo. — A late summer heat wave is underway in Jackson Hole with well-above-average temperatures expected for most of the week. Wildfire activity across the Western U.S. and an uptick in thunderstorm chances locally will round out the main topics of discussion in weather this week.
Impressive Late Summer Heat Wave
On average, the hottest time of year in Jackson Hole runs from about mid-July through the first week of August with average temperatures starting to trend downward from the second week of August on.
However, summer’s warmth is turning out to be “back-loaded” this year with our hottest stretch of weather this season set to occur over the next 10 days.
A powerful ridge of high pressure has taken hold across the Western U.S. and numerous record high temperatures were set over the weekend. Boise saw a record high temperature of 103 on Sunday, and even Seattle recorded a high of 97, which was also a record.
The most impressive temperature of all occurred in Death Valley, Calif. — the nation’s hot spot — where a high of 130 degrees was recorded on Sunday!
This recording is only preliminary as of this time, but if it becomes “official” after a climatology review, it would go down as the hottest temperature recorded in Death Valley — and the U.S. — since 1913, and possibly the hottest ever since weather observations have become more reliable (some recordings were not so reliable in the 1910s).
Fortunately, we don’t have to worry about triple-digit heat in Jackson Hole, but it’s still going to be quite hot by our standards this week. On Monday, highs will reach the low 90s in the Jackson Hole Valley, which will challenge record highs for the date.
The rest of the week will be slightly cooler, thanks in part to an increase in cloud cover over the middle part of this week, but above-average temperatures are expected for at least the next 10 days.
Wildfire Activity Picking Up Across the Western U.S.
Fortunately, we have managed to avoid any significant wildfires locally so far, though that could change in a hurry in this hot and dry pattern.
However, wildfire season has quickly picked up across portions of the Western U.S. in recent days and weeks. The image below is a projection of smoke in the atmosphere on Monday afternoon (darker red colors indicate thicker smoke).
We experienced some hazy skies in Jackson Hole on Sunday afternoon, and this was a result of smoke from California wildfires drifting into Western Wyoming.
Farther south, some of the worst recent fires have occurred in Colorado, including the Pine Gulch Fire which has burned over 81,000 acres north of Grand Junction, and the Grizzly Creek Fire which has burned over 25,000 acres near Glenwood Springs and has forced I-70 to close.
However, the most remarkable fire incident over the weekend occurred in Northern California when a rare fire tornado (yes, you read the correctly) occurred with the Loyalton Fire. Pictures and a detailed account can be found HERE.
The National Weather Service even issued a Tornado Warning for this “fire tornado” — the first time a warning has ever been issued for such an occurrence.
Renowned atmospheric scientist Dr. Marshall Shepherd from the University of Georgia wrote an excellent article explaining the science behind the fire tornado HERE.
Thunderstorm Activity to Increase Across the Tetons this Week
In addition to hot temperatures and occasional hazy skies due to wildfire smoke, an uptick in thunderstorms will also occur across Western Wyoming, especially from Tuesday through Thursday.
The culprit will be a surge of moisture from tropical activity in the Pacific that will stream above and around the periphery of the high pressure ridge and into Idaho, Montana and Wyoming.
Storms will generally move from west to east this week with the best coverage of storms occurring over the Tetons and surrounding mountain ranges as well as the Northern Jackson Hole Valley.
Thunderstorms this week will not be “dry” per say as brief downpours will be possible with any storms, but widespread significant rains are not expected either. Therefore, there will be a threat for lightning-triggered wildfires this week.
By Friday, moisture will exit our region, giving way to dry (and hot) conditions heading into the weekend.
Looking out into the extended range, we could see another uptick in moisture and thunderstorm chances next week courtesy of tropical activity in the Eastern Pacific, with some early signals of a cool-down toward the end of August.
Alan Smith, Meteorologist
