All posts by Jim Woodmencey

Winter Solstice & White Christmas

Mountain Weather Blog


Today is the Winter Solstice, as the Winter Season officially began here in the Rocky Mountain time zone at 4:12 a.m. this morning. And so far at least, the World hasn’t ended today!
Also thought of as the “shortest day of the year”, our shortest days actually last about a week. The length of day between sunrise & sunset being 8 hours and 57 minutes, which actually started on Dec. 18th and will last through Christmas Day, before we gain a minute of daylight on Dec. 26th. By New Year’s Day, we are up to a full 9 hours of daylight here in Jackson Hole.
White Christmas & Snowcover
Below is a visible satellite photo taken from space (of course) of the north-central part of the Rockies showing the actual snowcover throughout the region, taken Wednesday, December 19, 2012. (Sent to me by Steve Poole, thanks Steve).
Looks like only a few spots in the region that are at risk of not having a White Christmas this year.
Speaking of Christmas, here in Jackson Hole anyway, I will be sending everyone a little fresh snow this Christmas Weekend. Enjoy, and have a Merry Christmas!
Link to that page from the NASA Earth Observatory is here:
Rockies Snowcover as seen from Space
Posted by meteorologist Jim Woodmencey
Picture courtesy of NASA

A Good Snow & Blow Session in Mid-December

Mountain Weather Blog


With only a few days left until the official start of Winter on December 21st (or the end of the World, as the Mayans are calling for!), we are already well into the Winter Season with plenty of snow around Jackson Hole to guarantee a White Christmas for the valley. In the mountains, there is a ridiculous amount at the higher elevations in the Tetons, for this early in the season.
The Snow
From Friday through Monday around 20 inches of snow fell at around the 9500-ft. elevation in the Tetons. The Raymer weather station at the Jackson Hole Mountain Resort tallied 25 inches. And even over on Togwotee Pass 13 inches of snow at about the same elevation was measured at Brooks Lake Lodge and by the SnoTel instrument.
The Blow
It was the wind on Monday December 17th that was even more impressive, with average wind speeds at top of the Tram exceeding 40 mph at times and a maximum gust of 78 mph. Top of the Headwall had a gust of 75 mph.
Wind Graphs from Monday, December 17, 2012
Top of the Tram
10,450-ft. at JHMR
Mt. Coffin
10,850-ft. in the Salt River Range
 
Tram weather station
Mt. Coffin weather station
 

Record Wind Gust??

The big winner for wind speeds on Monday was Mt. Coffin in the Salt River Range east of Afton, WY at 10,850-ft. The weather station up there on that ridge clocked average speeds of over 100 mph and had an “unverifiable” gust of 266 mph.
Yes! 266 mph! That was about the same time the core of the jet stream was over Wyoming with winds at 30,000-ft. in excess of 150 mph. (See jet map). Possibly an erroneous reading as a result of the way the electronics in these instruments handle gusts??
IF this wind gust was verifiable, it would qualify as the highest gust ever recorded on the face of the earth. You might have thought the 231 mph gust on Mt. Washington in New Hampshire was the highest ever, back in 1934. That record was actually beaten by a wind gust during a typhoon in Australia back in 1996, with a measured gust of 253 mph.
BUT, I already checked with the folks who run the MesoWest at the University of Utah, the clearing house for all these weather stations, and they suspect that these super high gusts are false values that the electronics are providing in these instances.

Jet Stream Monday Dec. 17, 2012
Post by meteorologist Jim Woodmencey
Data from MesoWest
Photos from Bridger-Teton
Jet map from MeteoStar

Deepest Snowpack in 15 years!

Mountain Weather Blog

Update this morning to yesterday’s post:  With  a foot of new snow at around the 9,500-ft. elevation the last 24 hours, the settled snow depth at the bottom of Rendezvous Bowl at the Jackson Hole Mountain Resort is now deeper than it has been on this date (Dec. 8th) in the last 15 years, with a  61 inch depth reported, that’s a solid 5 feet!

We just surpassed early December 2010 snowdepths (59 inches). You would have to go back as far as Decemeber 1996 to find a deeper snowpack on this date ( 73 inches).

Total snowfall so far this season recorded at the Rendezvous Bowl weather station is 124 inches. Still shy of the total from 2010 on this date (160 inches), but well above the average for this date (104 inches). And far and above last winter’s start with just 87 inches, and only 28 inches of settled snow depth on December 8, 2011.

AND…….the valley got around 3 inches of snow overnight, as well. That should guarantee a White Christmas for Jackson Hole.

Gotta go skiing now……because that foot of snow is all light density stuff!!

Posted by Jim Woodmencey

Mountain Snowdepths Above Normal

Mountain Weather Blog

Finally, a little white for the valley in early December. It is amazing the difference we are seeing between the upper elevations and the valley floor this early winter season. At the Jackson Hole Mountain Resort at the bottom of Rendezvous Bowl (around 9500-ft.) there was 52 inches of settled snow depth on December 7th. Last year on this date there was only 27 inches of settled snow. The average snow depth for the date here is 42 inches. Just a trace of snow in the Town of Jackson this morning.
But what is truly amazing is that two winters ago in December of 2010, the start of that huge Winter of 2010-11 we had 59 inches, so we are only 7 inches behind that early December depth. (See chart below).
As a matter of fact, this is the second deepest snowpack we’ve had at this location in the last 15 years!
Early December 1996 was the last time Rendezvous Bowl had more than 59 inches, with a 72-inch base up there to start the season.
Now we just need to send some of that to the bottom of the Hill.
The Teton Mountains have done well these last two weeks, and temperatures are cooling down this weekend, getting downright cold, with some nice, light dry powder to top off this base in the mountains, and paint the valley with its first good coat of white, that will likely stay put this time around.

Posted by meteorologist Jim Woodmencey

The Jet Stream Dictates our Weather

Mountain Weather Blog

It’s Thanksgiving, and technically Winter is still a month away. And the weather pattern that would bring winter on in full is still not quite there yet for the Rockies. Lots of snow the last few days in the Cascades, where cold air and the jet stream have been hanging out. And a  little new snow in Jackson Hole this morning from the storm passing through last night.  Looks like one more shot of snow this weekend, again starting warmer on Saturday and cooling Sunday into Monday, will also help kick off the ski season.

However, the split jet stream that has been over the Western U.S. needs to go away, and the main Polar Jet stream that carries both Pacific moisture and cold air from the Gulf of Alaska need to dip a little further south. It dipped over us last night, but will stay north of Wyoming Friday & Saturday.

We do see the jet dip south again over the weekend, but then by the middle of next week it looks like it will head back to the north of us.  Therefore, we may have to wait a bit longer for that jet to straighten out and get us fully into a winter storm cycle.
(See maps of current jet, forecast jet late Sunday & forecast jet next Thursday).

Thanksgiving Day
Sunday Night, Nov. 25th

 
Next Thursday Nov. 29th

General Weather Rule of Thumb: When the core of the jet stream is north of us, we get warmer and drier weather. When the jet is right over us, we may get Pacific moisture, but temps may be too warm and we get rain at lower elevations. When the jet is just to the south of us, that is usually when we get our best snowfall.

I’ll keep an eye out for changes and update the long range outlook for you in the next blog post.

Text by meteorologist Jim Woodmencey
Maps from NCAR

First Snow & Winter Outlook Update

Mountain Weather Blog

A cold low pressure system brought us almost a foot of new snow in the mountains up at around 10,000-ft. in the Tetons over the last 24-hours, and this would certainly qualify as our first good snowfall of the season.

It also looks like we had about ¾ of an inch of water in the valley from this storm and over an inch of water at the higher elevations in the mountains. That should be enough to put us over the average precip for the month of October in Jackson.
Forecast Weather Map for Thursday Oct. 25
That Low pressure system is still sitting along the Pacific Northwest Coast and looks like it will keep temps cool the rest of this week and also produce some more snow as that Low sifts inland and dies out at the end of the week. (See Forecast Map for Thursday).
I’d like to say that the snow will just keep coming right through Christmas, but that scenario would be a gift, for sure, and does not seem very likely. And that is also what the Climate Prediction Center seems to think as we go into the winter months.
December – January – February Outlook

The Climate Prediction Center (a division of NOAA and the National Weather Service) is not painting a pretty picture with their latest 3-month outlook for December through February, with above normal temps for most of the Rocky Mountain West, and below normal precipitation for the Northwestern portion of the U.S.  
(See maps below and keep up with all the latest short & long range outlooks on the NWS Discussions Page of mountainweather.com)
3-Month Outlook Maps for December- January- February 2012-2013
Temperatures
Precipitation
ENSO Update
The El Nino Southern Oscillation (ENSO), in other words, what’s happening with the sea-surface temperatures in the Equatorial Pacific, is now trending towards either Neutral Conditions (No Nino) or a weak El Nino for the winter.
I personally don’t like the “No Nino” situation, as the odds are usually against us having an above normal snowfall winter in the northern Rockies. But I would take a weak El Nino and put money on a snowier winter than 2011-12, although not as snowy as the Winter of 2010-11, both La Nina Winters.
That’s about as much as I can tell you right now, as technically I am still on my fall break and not forecasting on a daily basis. I have some weather classes I am teaching over the next couple of weeks (one in Alaska & then one in Florida, followed by one in Jackson!), plus I will be working on updates to the mountainweather.com website for the winter.
Text submitted by meteorologist Jim Woodmencey
Graphics from NOAA

Cold Air Wake Up Call

Mountain Weather Blog

Cold Canadian air pushed down through Wyoming on Wednesday, with high temperatures almost 20 degrees cooler in Jackson Hole than they were the day before, on Tuesday. Highs in Jackson Tuesday were in the lower 70’s, on Wednesday we were in the low to mid 50’s.

Low temps this morning (Wed. Oct. 4th)  changed even more radically, with overnight temps almost 35 degrees colder than on Tuesday morning…..with lows in the teens most places, whereas the lows on Tuesday morning, before the cold air arrived were in the upper 40’s to near 50.

Coldest temps as of 7:30 a.m. Wednesday morning around the Jackson Hole Region:
Town of Jackson =19 
JH Airport = 16
Moose = 14
South Park = 15

Cold air now pushing south into Utah & Colorado. Snowing in North Dakota & northern Minnesota. Snow will be staying well north of the cold front and to the east of the Continental Divide in WY & MT.  (See today’s weather map, & forecast map below). See more forecast maps on USA Forecasts Page on mountainweather.com

Wednesday Oct. 4, 2012 Surface Analysis

Forecast Map for Oct. 4, 2012

First Blast of Cold Canadian Air

Mountain Weather Blog

Cold air pushing down through Montana this morning, with snow down along the east side of the Continental Divide down to fairly low elevations, like around Pendroy, MT located northwest of Great Falls and just east of the Rockies ( Web cam pic below).

US Hwy 89 Near Pendroy, MT

And snowing down into Southwest Montana around Bozeman & Livingston. (See pic from cam on Bozeman Pass). And Beartooth Pass closed this morning, due to winter weather!
Snow showers will push down through parts of Yellowstone Park today, along the Continental Divide.

I-90 over Bozeman Pass, MT

In Jackson Hole, we’ll get the cold air, and the wind out ahead of that push of cold air, but snow will stay east of the Divide. Only a small chance of a few flakes over the west side of the divide in Northwest Wyoming today.

Read more about what is causing the weather this week by reading the “Full Weather Discussion & Outlook” at the bottom of the Jackson Hole Forecast Page.

Post by meteorologist Jim Woodmencey
Wednesday, October 3, 2012

Fall Colors on Schedule

Mountain Weather Blog


This past Saturday, September 22nd, was the Autumnal Equinox and the official end of summer and start of the Fall Season. Almost as if on cue, good fall colors can be seen over the Rocky Mountain West. This last week in September and the first week in October seem to be normal timing for peak fall colors, this year no exception.
One exception I did note while flying back to the Tetons from the East Coast, on the day of the Equinox, a route that took me over the Northern Colorado Rockies (very yellow at high elevations!) and up along the Wasatch and northern Utah mountain ranges,  was how much red there was to the leaves in the mountains of Utah this year. More mountain maples than aspen trees, perhaps?
With the weather the next 7 days or so shaping up to have cooler mornings at all elevations, getting down to freezing or just below, we should see an acceleration in the color change. We will also experience fairly light winds at all elevations thru early next week, which will help to keep the majority of those leaves on the trees.
This is one of my favorite times of the year to get out an hike or ride my bike and soak in the golds & reds, a nice contrast to the greens of summer and white of winter.

Text & photo submitted by meteorologist Jim Woodmencey