All posts by Jim Woodmencey

Welcome Changes in the Weather


Finally some warmer temps and a little fresh snow on Thursday. And it looks like more snow will be possible for Jackson Hole over the weekend, especially on Sunday. I like the way things look to be shaping up.
After a long period of High & Dry & Cold in early January, the changes are certainly welcome. Read on for all the rap from this Friday morning’s forecast……..
Weather Discussion from MountainWeather Forecast for Jackson Hole
Friday, January 27, 2013
We have a split jet stream flow over the Western U.S. today, with one segment of that jet to the North & NW of Wyoming, and the other segment to the South & SW.
We are in-between those jets, with weak High pressure over us trapping leftover moisture from yesterday, keeping some stratus cloud / fog layers around the mountains this morning.
Weather Map for Sunday January 27, 2013
Two Low pressure centers off the Western Coast, one near SE Alaska, which will drop southward over the Pacific Northwest this weekend. And one in the upper levels of the atmosphere off the Southern California Coast.
Those Lows will merge into one larger Trof of Low pressure as they move inland across the Western U.S. this weekend, combining cold air from the northern Low with moist air from the southern Low.
That will produce a moderately strong West to SW flow and also produce some snow around JH. Especially as the jet stream comes together a little better over us on Sunday.
That Trof will take its time crossing the Rockies Monday, bringing much cooler air over us, keeping the atmosphere unstable enough to keep on producing snow showers.
Some drying of the atmosphere Tuesday as we come under more of a Northerly flow. But Wed. thru early Friday it looks like we may get into more of a NW flow, with enough moisture in it to keep some light snow & snow showers going over the mountains.
A Ridge of High pressure over us later Fri. thru Sun. with dry weather next weekend.
Posted by meteorologist Jim Woodmencey
Map from NWS.

The Weather Access Map for Jackson Hole

Merry Christmas!
The Wx Access Map for Jackson Hole (Wx is shorthand for Weather, by the way) is designed so that you can access both current weather observations and forecasted weather for specific locations in the Grand Teton & Yellowstone Park region.
The coverage area on this particular map, if you scroll out, extends from Bondurant to the south, all the way to Mammoth in the northern part of Yellowstone Park. East to Togwotee Pass and West to Idaho Falls.
Each Icon on the map is located where there is a weather station, at a variety of valley, airport, and mountain locations.
See the bottom of the Wx Access Map page for an explanation of the different formats that are available for you to view, for both weather observations and weather forecasts for these locations.
Where there is a webcam nearby, or one that has a view in the direction of the station, a thumbnail link to that is included in the pop-up window.
At the bottom of the page are the local Satellite & Radar maps, etc.

What is a “Point Forecast” 

Before you completely abandon the forecast I produce each weekday for Jackson Hole & the Teton Mountains, you should understand how these point-forecasts are derived.
“Point-Forecasts” are available everywhere on the internet now, they are the “go-to” tool that most websites are using to generate a “local” forecast. They are a bi-product of the National Digital Forecast Database (NDFD) from the National Weather Service and are almost completely computer generated from almost 3 million data points across the Continental US. There is some human input involved, as NWS forecasters have the ability to tweak the data they get from the NDFD, adjusting temperature lines, etc. But after that, it is the computer that interpolates all the weather variables “between the lines”.
The “point” part of the forecast isn’t exactly a pin-point location, but rather a grid box that covers an area of a couple of square miles, or roughly the size of Jenny Lake. But in the mountains, that includes all elevations within that grid box. Again, the data you get is interpolated for that approximate latitude, longitude, and elevation.
Point-Forecasts have a very high “coolness factor” to them because of the endless graphical display possibilities, and the ability to give you forecast data by the hour! But we all know, the weather changes, a lot, and the actual weather you get may vary considerably from what the forecast says is going to happen.
I have meticulously selected the closest representative grid box for each of the locations on the map, to give you the best representation of the weather forecast information as possible, for both the NWS versions and the WeatherSpark version.
Check out what the guys at WeatherSpark have done with their graphics, of basically the same data! There’s hours of fun to be had playing with their graphs! When you click on a link to a WeatherSpark Point Forecast, their Google map to the left, locates the station and also has local radar overlaid on the map. Close that map to see more of the graph. Use your mouse wheel to expand or contract the graph. Very COOL!

Caveats 

Keep in mind as you use these forecasts, as with any forecast, they are “guidance” not “gospel”. And I have found that the point forecast data does well with temperatures, not as good with wind, and even less good with precipitation probability and amount.
Where this map will be most useful for me is for areas just outside of the Teton area, up into Yellowstone or on Togwotee Pass, or down the Hoback. Places that are outside the coverage area of the MountainWeather Forecast for Jackson Hole & the Tetons.
I still do my Jackson Hole Forecast from scratch every weekday, and there is way more human input going into that forecast than what goes into the computer generated point forecasts.
Just like a new toy at Christmas, play with this map and see how you like it. Please send me feedback on what you like or don’t like about them and I will try to make changes as this project moves ahead.
Additional points may be added to this map in the future, to cover popular locations that do not have a weather station associated with them, to at least provide the point forecast for those locations. Although, I will be hesitant to crowd the map with too many icons. You are welcome to send me a request for your favorite spot on the map. If I get enough requests for that spot, I’ll consider adding an icon.

More to Come 

The Wx Access Mapis phase-one of a project I have been working on since early this past summer. The Jackson Hole-Teton-Yellowstone Map is the first to be completed. Others will follow this winter, for each of the Mountain States. A Wyoming Weather Page will be finished very soon, the other Rocky Mountain States will get their own weather pages next, then the final phase will include pages for the Pacific Northwest (WA/OR/CA).
The individual Mountain States pages will be more or less one-stop weather pages that will include some quick-look, easy to interpret, weather information. As well as, a Wx Access Map for each state.
Happy Holidays from MountainWeather!
Posted by meteorologist Jim Woodmencey

Winter Solstice & White Christmas


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


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!

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

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

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

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

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