Extreme Weather GSM 

Late-Summer Snow Falls in Northwest U.S. as the Jet Stream Shifts South — Even Colder Conditions on the Way

Cool air funneled into the Western U.S. this week resulting in up to 10 inches of snow falling on the mountains of Utah and Wyoming. While looking ahead to next week, meteorologists see a much more potent cold air-mass sweeping the Pacific coast and Intermountain West.

This week’s cool air, which arrived in the Northwest on Monday, saw temperatures nosedive some 10C below the seasonal average. Snowflakes fell over the high country of the Tetons in northwestern Wyoming early Tuesday. And a decent dumping of the white stuff settled at Bald Mountain Pass, Utah:

Snow accumulating Sept 10 along Bald Mountain Pass, Utah (Photo/Utah Department of Transportation)


Up to 10 inches of snow is expected to fall in the higher terrain of northern and western Wyoming Tuesday night into Wednesday, in what the NWS is calling the first “fall-like storm” of the season.

Bighorn, Absaroka, Wind River and Teton mountains –including parts of Grand Teton and Yellowstone national parks– are all expecting healthy accumulations of powder above 8,000 feet.

With Thundersnow even possible in the Bighorn Mountains on Wednesday.

While a southward kink in the jet stream is responsible for this week’s cool down, a major buckling is forecast for next week — the recent chill is expected to pale in comparison to next week’s proper burst of autumnal cold.

“We expect snow to fall next week over the high country of the Cascades and perhaps the northern Sierra Nevada and northern Rockies,” said AccuWeather Senior Meteorologist Brett Anderson.

The upcoming pattern next week should deliver some of the first frosts and freezes of the season.

GFS TEMP ANOMALIES — SEPT 20

Temps to tumble as much as 16C below-average across the Western US next week


The Changing Jet Stream

Studying the jet stream has long been an indicator of the weather to come.

And to study the jet stream, attention must turn to the sun.

When solar activity is high, the band of meandering air flowing some 6 miles above our heads is tightstable and follows somewhat of a straight path. But when solar activity is low, as it is now (with NASA forecasting this next solar cycle “will be the weakest of the past 200 years”), the jet stream loses strength and its band of fast-moving air becomes wavy which, in the NH, drags Arctic air south to much lower latitudes than normal:


The cold times ARE returning, in line with historically low solar activity.

NASA’s has revealed that this next solar cycle (25) will be “the weakest of the past 200 years”:


Prepare for the cold — grow your own.

Grand Solar Minimum + Pole Shift

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One Thought to “Late-Summer Snow Falls in Northwest U.S. as the Jet Stream Shifts South — Even Colder Conditions on the Way”

  1. Myron Anduri

    The events in this posting are not that unusual. I have lived in the high elevations of Colorado for almost 40 years and snow during the Labor Day holiday is not a huge surprise. I came to Colorado in 1967 as a young man and my neighbor, who was an avid camper, told me that of you camp in the mountains expect snow on Memorial Day and Labor Day. After several decades of warmth I had forgotten that advice until lately. Weather repeats itself.

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