Posted by meteorologist Jim Woodmencey
All posts by 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).
|
|
|
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.
![]() |
Forecast Weather Map for Thursday Oct. 25 |
3-Month Outlook Maps for December- January- February 2012-2013
|
|
Temperatures
|
Precipitation
|
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 |
First Blast of Cold Canadian Air
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
Horsethief Fire Weather Page
If you are really into the weather and especially weather related to fire behavior, you can follow along more closely with information posted on the NWS Riverton website page that was set up to assist the fire weather forecasters working the Little Horsethief Wildfire near Jackson,WY.
Main link is here: NWS Horsethief Fire page
I will set up a direct link to this page at the top of the Jackson Hole Forecast Page and also under the Fire Weather Information section at the bottom of the Jackson Hole Information Page on www.mountainweather.com
Some of the cool stuff of interest might be the Hi-resolution Satellite photos that show the smoke plume best when skies are clear during the day, see below:
Hi-Resolution Visible Satellite Photo of Wyoming |
There is much more to view here, some of it is more technical fire weather forecast products & computer models, but other info of general interest is the Loop from the Web Cam on top of Teton Pass that looks towards the fire.
And also the Fire Weather Briefing Page for Teton County Emergency Managers
(click the bold print).
Posted by meteorologist Jim Woodmencey
9-12-2012
Fire Weather & Air Quality
Horsethief Fire September 9, 2012
|
First shot from Munger @ 2:00 pm
|
Last shot from Munger @ 3:15 pm
|
Taken from Rodeo Grounds in Jackson @ 5:00 pm
|
Where to Find Fire & Air Quality Info
Photos by Jim Woodmencey
Winter Weather Outlook 2012-13
(Reminder: Prices increase Sept 1st for the Jackson Hole Mountain Resort. After Sept. 16th for Grand Targhee).
Long Range Outlooks
NWS Discussions Page of mountainweather.com)
3-Month Outlook Maps for October-November-December 2012
|
|
Temperatures
|
Precipitation
|
El Nino Year
(El Nino years in blue and La Nina Years in red.)
Text submitted by meteorologist Jim Woodmencey
Cool Cumulus Clouds
Late afternoon and early evening (between about 4:30 and 8:30 pm) on Friday July 27th there were some very cool looking cumulus clouds associated with thunderstorms around the Tetons & the Jackson Hole area.
Most of these would be classified as Cumulonimbus Mammatus Clouds. That is, they were of “cumulo-form” (tall & puffy)…… They produced some rain, so they also get the suffix “nimbo”…. And, they had the mammary shapes extending from their bases, thus “mammatus”.
Photo by Scott Guenther |
The bulbous extensions beneath the clouds are indicative of strong updrafts and downdrafts within the thunderstorm. Whether or not the thunderstorm spits out rain or hail at that point depends on if the falling precipitation within the clouds can overcome the updraft speeds.
Below is a collection of photos sent to MountainWeather after the storm, and some that I captured while on a long hike through the Tetons that day, while on a patrol with some old Jenny Lake Ranger friends of mine.
Posted by meteorologist Jim Woodmencey
|
|||||
|
|