This past week has been warmer than normal over much of the Western United States, warm at least for late May and early June. In Jackson Hole we just had a string of days topping 80 degrees, 82-degrees for a high temp in town on May 29, 30 & 3, 2020. Looks like we’ll be back to around that same temp at the end of this week. Then, it gets abnormally cold for early June.

None of that was record high territory, but it sure feels warm for this time of year. Back in 2003 Jackson had a high of 90-degrees on May 29th and in 1988 there was a a couple of days in the first week of June that tagged 89-degrees.

This weekend and into early next week is looking much cooler and also it looks like we’ll get some precipitation  this weekend, something that was lacking most of May.

Cold Low-Pressure Coming

A very cold Low-pressure system that is sitting in the Gulf of Alaska is going to slow-roll its way across the Pacific Northwest at the end of this week. A stronger southerly flow aloft ahead of that Low will bring the warm temps up from the Desert Southwest on Friday. Then the cooling begins Saturday through Monday.

We could see a drop in temperatures of almost 40-degrees, based on daytime highs. That means by Monday, June 8th, the high temps in Jackson might not get out of the 40’s! The number to beat on that date is a high of only 43-degrees, which occurred here in 1950, for a record cold maximum temp.

Mountains also go Warm to Cold

Mountain temperatures have been very warm this past week, as well. Highs at the top of the Tram at Jackson Hole Mountain Resort were tagging 60-degrees this past weekend, with overnight lows temps in the 40’s up there. The freezing level during the day were was above the summit of the Grand Teton (14,000-ft. +).

CLICK image below to play video of computer model forecast.

This has led to a pretty good melt-down of the snowpack and subsequent run-off into the creeks and rivers. That will all screech to a halt after this weekend. Looks like by Monday the temperatures will not get above freezing at 10,000-ft.

Hope you didn’t get too used to the warm, because it is about the swing in the other direction.

Keep up with the latest forecast info for Jackson Hole and the Teton Mountains as the weather this weekend goes through these changes: Click for JH Forecast

Post by meteorologist Jim Woodmencey

You have probably heard the old saying that Jackson Hole gets nine months of winter and three months of bad skiing (substitute: boarding or sledding here). Some years, that is very true, as winter weather can start in September and last until June.

Last month on this Blog, I reviewed the “meteorological winter” season, which includes the months of December, January and February. In this post, I will add the month of March to the mix, to tally up how much snowfall there was during the traditional ski season ( December 1st to April 1st) .

Snowy March Piles it On

A big storm mid-month dropped a record daily snowfall amount in town, with 12 inches in 24-hours on March 14th. Jackson Hole Mountain Resort also broke a record for that same date in March, with 23 inches of snow in 24-hours.

Snowfall in town for the month of March tallied up 24 inches, more than double March’s average snowfall of 11 inches. By the way, that was only 2.5 inches shy of the record snowfall in March of 26.5 inches set back in 1985.

Mountain snowfall in March was also above the norm for March, with 86 inches of snow recorded at the Rendezvous Bowl weather station at the Jackson Hole Mountain Resort (Elevation 9,580-feet). Almost 20 inches more than the average snowfall for March of 67 inches.

Plentiful Valley Snowfall

Adding up snowfall numbers from December 1st, 2019 through March 31st, 2020 for the Town of Jackson Climate Station: 89 inches of snowfall was recorded during that four-month period. That is 28 inches more than the historic average snowfall for December through March, which is 61 inches.

If you add October & November 2019’s snowfall amounts to that total (15 inches), then our six-months of “winter season” snowfall total goes up to 104 inches. That’s well above the historic average for those six months in town, of 71.5 inches.

Abundant Mountain Snow

The total snowfall for the traditional “ski season”, December 1st to April 1st, at the Rendezvous Bowl weather station at Jackson Hole Mountain Resort was 417 inches this winter.

That is over 100 inches more snow than the long-term average for that four-month period, at that location. Average snowfall for December through March, at the Rendezvous Bowl site is 308 inches.

January took the biggest prize this winter with a record-breaking 169 inches of snowfall for the month at Rendezvous Bowl. That was the snowiest January ever recorded at this weather station.

The grand total for snowfall measured this “winter season”, from October 1st, 2019 to April 1st, 2020, at Rendezvous Bowl, was 510 inches. That is 119 inches (almost 10 feet) more snow than the long-term average seasonal snowfall up there, which is 391 inches.

That exceeded last winter’s total snowfall of 496 inches but fell short of the total from the winter of 2016-17, of 560 inches.

As a matter of fact, this winter was one of only five winters on record that have exceeded the 500-inch mark at JHMR. Three out of those five have occurred in the last 10 years.

Upward Trend in Winter Snowfall

See graph below: 45 Year Snowfall Records at Rendezvous Bowl, Oct. 1st to April 1st.

I don’t want to jinx it, but it would seem that we are a roll with above average snowfall winters here in Jackson Hole. (See Graph).

Post by meteorologist Jim Woodmencey

Some of this content originally appeared in the Mountain Weather column of the Jackson Hole News & Guide

It’s springtime in the Rockies and that means wild weather swings are bound to occur. This week brought high temperatures in the 50’s on Tuesday & Wednesday to Jackson Hole. Then, a perfectly sunny day with no wind on Thursday and temperatures topping 60-degrees in the Town of Jackson.

That nice taste of spring weather all comes to an end this Easter Weekend, as what could be described as an “Alberta Clipper” will drastically change the weather across Wyoming. Satellite image below, from Friday morning April 10, 2020.

If you want to call it that, this “Clipper” is going to bring colder temps, wind & some snow to Wyoming. Technically, it is an upper level Trof of Low-pressure that will swing down from the north,  along the British Columbia & Alberta border. That Trof will then ride along the Continental Divide in Montana & Wyoming before swinging east across northern & central Wyoming on Sunday.

Most of the snowfall this weekend will be east of the Continental Divide.
(See Snowfall Forecast Map below).

Jackson Hole and western Wyoming will get some rain & snow showers on Saturday, but the real bummer is, we go from being sunny & warm with no wind, to cloudy & colder with windy periods this weekend.

Going from Shorts & T-shirts, back to Pants & Puffy’s.

Post by meteorologist Jim Woodmencey

On the night of April 5th, 2020 , moist & unstable air moved over western Wyoming causing thunderstorms and a relatively intense graupel event (round, puffy pellets of snow). In combination, this would be termed a “Thundersnow” event.

 Infra-red Satellite image below showing the bright green “cell” that contained those thunderstorms from Sunday night.

Thundersnow is rare and lightning this early in April is not that common. However, in the 38 years I have lived in Jackson Hole, I can say that I have seen lightning every month of the year, including during the depths of the winter season in January & February.

Below is the lightning strike map from 10:41 Pm MDT on Sunday. Yellow dots with red rings the most recent strikes, gold to brown indicates progressively older ground strikes, in the preceding hour or two.

Low-Pressure over California the Cause

A potent Low-pressure system that is sitting along the central California Coast , which has been bringing heavy rain to the Central Valley of California and heavy snow to the Sierra Nevada mountains,  is what was responsible for sending that moist & unstable air over the Inter-mountain West last evening. That air collided with colder, drier air that was in Montana.

Still a little more to come with this storm system Today (Monday)  and into Tuesday,  as that Low-pressure slowly makes it’s way over southern California. That means, western Wyoming is still in for a mix of rain & snow for the valley, snow in the mountains and the possibility of a few more thunderstorms embedded in all that.

Satellite view below from Monday morning. Low-pressure still spinning around along the California coast.

Snowfall Accumulation Forecast Map below for Monday morning thru Tuesday afternoon. (From CAIC-WRF model)

By Wednesday the center of that will be swinging by to the south of Wyoming, across the Four Corners Region and the weather in western Wyoming should improve for Wednesday-Friday.

Post by meteorologist Jim Woodmencey

A potent storm system in the Gulf of Alaska will bring snow to the mountains of the Pacific Northwest and Northern Rockies today through Tuesday, lingering into April Fool’s Day.

Map below shows position of Low-pressure Monday, March 30th and forecast position on Tuesday March 31st. Jet stream also pushes inland across Oregon, Idaho and western Wyoming through Tuesday, bringing lots of Pacific moisture in a strong Westerly flow aloft.

This storm system brings progressively colder air with it, causing snow to progressively lower elevations though Tuesday night. Very unstable atmospheric conditions will also cause some thunderstorms to develop.

By April Fool’s Day, it looks like snow accumulation in the mountains (especially above @ 9,000-ft.) will be significant: Oregon & Washington Cascades = 24 to 30 inches Central Idaho mountains= 12 to 18 inches. Tetons, Absaroka & Wind River Ranges= 12 to 18 inches also possible.

Snow Forecast Maps

Map below shows one computer model forecast of snow through Wednesday morning, April 1st.  (From CAIC WRF model).

Map below shows another computer model snowfall forecast for the same time period. ( From COD NexLab NAM model).

Look like March will go “Out Like a Lion” this year, across the Northwestern United States.

Post by meteorologist Jim Woodmencey