All posts by Jim Woodmencey

First Day of Spring?

Mountain Weather Blog


Spring officially began today, Wednesday March 20, 2013 at 5:02 a.m. MDT.  According to the calendar it’s Spring, but our weather the next few days will be more like mid-winter!

Large storm system over the Pacific Northwest and Northern Rockies bringing snow  then cold temps thru the weekend. No sign of warming back up until Tuesday of next week. So, fresh snow and cold temps to celebrate the Equinox in Jackson Hole!
(You can read more about it on the Jackson Hole Forecast page in my discussion).
Forecast Map for Wednesday, March 20.

More about the Spring Equinox
 
Also known as Vernal Equinox, “Vernal” the Latin word for Spring, and “Equinox” meaning equal day and night. The Equinox it is defined as the exact moment that the sun is positioned directly overhead at the Equator. The sun also rises due east and sets due west on the Equinox, which happens twice a year — in March and again in September.
During the days surrounding the Equinox, all locations across the globe, from the equator to the poles, will experience an equal amount of daylight and darkness, about 12 hours of each.
At this latitude in Jackson Hole the sun is now noticeably higher in the sky, 47 degrees above the horizon at noontime, versus 23 degrees above the horizon in December. And, our days are about 3 hours longer than they were back in December.
Post by Jim Woodmencey, meteorologist.
Graphics from NOAA & timeanddate.com

Listen to the Forecast

Mountain Weather Blog

Don’t like to read? You can now listen to MountainWeather’s Jackson Hole Forecast, anywhere, anytime. New audio version of the forecast is now available ………look for the audio button on the Jackson Hole Forecast page on both the main MountainWeather.com site and the mobile version of the website.

Listen on your computer, or your smartphone, when you are ready for your daily forecast!
Find this button at top right corner of the forecast on the main website
Find this button at top of the forecast
on the mobile site
This feature will be available each weekday morning by around 7:30 a.m. Not available on weekends or during my Spring Break period (April 15 to May 15). Sorry about that! But there will still be a local weather forecast posted from the National Weather Service, in its place, just no audio version.
A word about that upcoming Spring Break…..It is not as much of a break as you think, although I still believe in bringing back the off-season! I will be using that time this spring to make more upgrades to mountainweather.com and also teaching some courses to the US Military. If I’m lucky, I might get a few days on my mountain bike in Moab before I come back to forecast the weather for Jackson Hole for the Summer Season.
Enjoy the weather!
Jim Woodmencey, meteorologist

Spring to Winter to Spring: Snow for St. Patty’s Day!

Mountain Weather Blog

Hope you enjoyed the Spring weather this week, back to Winter weather in the Pacific Northwest  & northern Rockies for Saint Patrick’s Day Weekend.
The Ridge of High pressure that brought warm & dry weather this past week to the West & Rockies  gets flattened out and a Westerly flow develops from the Pacific Northwest across the Northern Rockies and into the Plains States, with gradually cooling temps.
A small, but very strong Low pressure system will move across the Pacific Northwest on Saturday, and be over Idaho Saturday night, with a strong cold front passing thru Western Wyoming on Sunday.
This potent little weather system will bring a pretty good shot of snow and much colder temps across the Pacific Northwest .
For the Jackson Hole Area, expect between 6 & 12 inches at higher elevations of the Tetons and 2 to 4 inches at lower elevations from overnight Saturday and thru the day on Sunday. Other mountain areas do pretty well also. (See forecast weather map and snowfall forecast map below.)
Snow showers linger early next week……..then on Wednesday, the First Day of Spring, a larger Low pressure system moves into the NW US with warmer temps initially, then another cold front plows across the Northern Rockies on Thursday. Bringing more snow & colder temps again the end of the week.  Looks like High pressure builds back over us for next weekend, with temps warming again.
Sunday March 17, 2013 Forecast Weather Maps
Surface Map for Sunday
Total Snowfall thru Sunday Evening
Post by meteorologist Jim Woodmencey
Graphics from NWS

March 2013: Lion Rides in on a Lamb

Mountain Weather Blog


As the old saying goes, “If March comes in like a Lion, it will go out like a Lamb”, and vice-versa. In other words, if the weather is winter-like and stormy to start the month, it will end with milder, more spring-like weather. Or, the opposite could be true, if it comes in like spring it will go out like winter.
This year it looks like the lamb will show up on Saturday and then be immediately devoured by the lion on Sunday across the Northern Rockies and at home here in Jackson Hole.
Saturday we should see temperatures in the Jackson Hole Valley topping 40 degrees in the afternoon, and temperatures at 10,000-ft getting up into the lower 30’s, with plenty of sunshine to give us a little taste of Spring. Then clouds increase Saturday night and a storm system that rolls across Montana will bring snow and colder temperatures to Northwest Wyoming on Sunday. 
Northwest Wyoming’s Teton Mountains should accumulate 6 to 9 inches Saturday night thru Sunday night. Northwest Montana & higher elevations in the Cascades of Washington might get a foot or so Saturday thru Sunday. And the Southern Canadian Rockies might score the biggest, topping two feet, but that includes snow from Friday and all day Saturday, as well as Sunday’s snowfall. (See Snowfall Forecast Maps below for this weekend).

Snowfall Forecast Maps Saturday thru Sunday March 2nd & 3rd
Northwest USA
Zoom on Wyoming & Utah

 
The Rest of March 2013

How the month ends weather-wise is no more conceivable than how it started……do we call it Lion or Lamb-like?

Not much change is indicated in the longer range computer models for March, and a “neutral” or No-Nino condition in the Equatorial Pacific that began in January is expected to last through our Northern Hemisphere Spring.
What is interesting about this March is that temperatures are expected to be below normal. Surprising, because the trend over the last couple of decades has been that temperatures in the month of March in the Rockies have been climbing. Oddly, March is the one month of the year that the statistics in Jackson at least have been consistent and indicating the most warming in the long-term climate trend the last 50 years. So, maybe we are starting a trend to even that out a little.
Precipitation Outlooks in March still indicate “equal chances of being above, below, or at normal” for the monthly precipitation (and snowfall) this March, across the Pacific Northwest and Northern Rockies.
You might interpret that to mean that there would also be equal chances of March going out like a Lion or a Lamb.  A wooly one at least, since temperatures are supposed to be below normal.
 (See the 30-Day Outlook Maps below).
30-Day Outlook Maps for March 2013
Temperatures
Precipitation
Post by meteorologist Jim Woodmencey
Graphics from and NWS

Second Half of Winter Outlook

Mountain Weather Blog


The Climate Prediction Center or “CPC” (a division of NOAA and the National Weather Service) is responsible for producing our long-range outlooks. For the next three months they are showing that the Pacific Northwest will be about the only place in the USA that has a good probability of experiencing below normal temps. Nowhere in the western US is expected to see above normal precipitation. The Southwestern US has a higher probability of seeing below normal precipitation February thru April.

Alaska, the Pacific Northwest, Idaho, Montana, and Wyoming will be sitting basically in a climatalogical  no-man’s land during February thru April, as far as our chances of precipitation go.
The CPC determined that this part of the country will have “Equal Chances” of being above normal, below normal, or normal, in the precipitation category.
That pretty much covers it!
So, I could interpret that to mean we’ll either get dumped on, or not not get dumped on, or have something in-between. A very helpful bit of insight. Not.
(See more maps and follow the latest short & long range outlooks on the Long-Range Outlooks Page of mountainweather.com)
3-Month Outlook Maps for February-March-April 2013

Temperatures
Precipitation

El Nino-La Nina-No Nino

While we began the Winter of 2012-13 with a weak El Nino condition in the Equatorial Pacific (that is, slightly warmer than normal sea-surface temperatures off the coast of Peru), indications are that we are transitioning to more of a “Neutral” condition in the Equatorial Pacific as we head towards the Spring Season. What I will call a “No-Nino” situation.

What does that mean for us? Basically,nothing. As you can see from the 3-month outlooks above, the long range forecasters are calling it an even bet on both precipitation & temps for the northern Rockies at least, including Jackson Hole.
You might interpret all of this to mean that we will have a “normal” second half of winter and start to the spring season. If there is such a thing as normal weather in Jackson Hole!
Text submitted by meteorologist Jim Woodmencey
Graphics from NOAA

It’s Groundhog’s Day!

Mountain Weather Blog


Saturday February 2nd, 2013 is Groundhog’s Day! A very important day to a weather person! Groundhog’s Day really has nothing to do with a rodent seeing his shadow, and in the Rocky Mountains it would be rare to not have at least six more weeks of winter. The real significance of Groundhog’s Day is that it marks the halfway point of the “Winter Season”, between the Winter Solstice (Dec. 21st) and the Spring Equinox (Mar. 21st).

Skiing In Grand Teton National Park in late December 2012
The first half of the winter throughout the mountains of the western United States was up and down. In general, it could be characterized by healthy snowfall in December, followed by a long stretch of drought, along with some brutally cold temperatures for a good portion of January. With a period in there when even up at elevation temps were well below zero, before inversions set in.
Jackson Hole Snowfall

In the Teton Mountains, the snowfall and snowdepths we have presently are not too far off of the averages , December’s above normal snowfall in the mountains almost balanced the below normal snowfall of January.
At the at the bottom of Rendezvous Bowl at 9,580-ft. at the Jackson Hole Mountain Resort, 114 inches of snowfall was recorded in December 2012 and 45 inches in January. That’s a total of 159 inches for the two months, and the historical average for the two months is 163 inches.
As of this morning, February 1, 2013, there was another 7 inches recorded and the settled snowdepth at the Rendezvous Bowl site was reported to be at 73 inches. The average on February 1stis 78 inches. Last year we were at 72 inches. (See summary table below).
Total snowfall so far this season at the Rendezvous Bowl site was at 240 inches. The average at this time of year would be 249 inches, and last year we were only at 198 inches.
Just under average, and just ahead of last year.
First Half of Winter Snowfall Summary & Comparison
Total Season’s Snowfall
as of Feb. 1st
Settled Snowdepth
on Feb. 1st
2012-13
240 in.
73 in.
2012-12
198 in.
72 in.
2010-11
306 in.
87 in.
2009-10
265 in.
83 in.
Average  
249 in.
78 in.
What’s Ahead for the Second Half?……………
I’ll put that in a post later this weekend. After I ski Rendezvous Bowl on Saturday and before the Super Bowl this Sunday. (Providing I don’t ski in the morning before the Super Bowl).
Post by meteorologist Jim Woodmencey
Data from Bridger-Teton Avalanche Center

Welcome Changes in the Weather

Mountain Weather Blog


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

Mountain Weather Blog

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

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