Groundhog’s Day Weekend 2019 looks like it will be a snowy one for the mountains of the Western United States…measured in feet of accumulation in some places!

Three separate Low-pressure centers will develop and combine to give the weekend a one-two-three punch, beginning in the Sierra Nevada mountains Friday night, February 1st, extending inland to the Rockies beginning later Saturday, February 2nd, and continuing to snow across the Western U.S. thru Monday, February 4th.

BIG SNOW LOCATIONS

This combo of storm systems will accumulate decent snowfall, especially for some parts of the Sierra, exceeding 5 feet!

The mountains of Northwest Wyoming should do well, with 15 to 20 inches in the Tetons, 2 feet or more in parts of Yellowstone Park and in the Wind River mountains.

Below is the NAM model prediction, from NexLab:

Below is the CAIC forecast snowfall accumulation for Friday afternoon thru Monday afternoon, Feb. 1 to 4, 2019 and it is just as robust as the NAM with the snow accumulation thru the weekend.

Happy Groundhog’s Day, the official halfway point of the winter season!

Post by Meteorologist Jim Woodmencey

Friday Jan. 18, 2019

The Low-pressure center that brought good snowfall across the mountain of the Western U.S the last couple of days has moved east into the Plains States.  A Ridge of High pressure is now building along the West Coast today, and that Ridge will move east across the Rockies over the Martin Luther King Holiday Weekend.

This will result in a Northwesterly flow over the northern Rockies Saturday. Then transitioning to a Southwesterly flow Sunday, ahead of a small upper level disturbance. See Jet Stream (@35,000-ft.) loop below for Friday thru Monday.

Saturday-Monday, Jan. 19-21, 2019

Temperatures in the Rockies will warm aloft as that Ridge builds inland Saturday. Some rain mixing with snow at lower elevations. Best snowfall accumulations look to be Saturday night thru Sunday, for Sierras, then the Ridge shifts east of the Rockies and colder air returns Sunday-Monday, with best snowfall for Rockies.

SNOWFALL FORECAST MAPS

The Sierra Nevada mountains & the Rockies get some snow from the NW flow & then the WSW flow ahead of  the next disturbance moving in from the Pacific. Models vary in the total amounts for different geographic areas…….

For Example: In the Teton Range of Western Wyoming the NAM shows 10 to 15 inches of accumulation thru the MLK Weekend, whereas, the WRF show much more, 20 to 24 inches.

This flip-flops for the Sierra Nevada Range in California, where the WRF shows 10 to 15 in, the NAM has much more, >24 in.!!

Go figure? Which model will be correct? (See maps below to compare).

By the way, the storm that is exiting the Rockies today will be bringing snow to the mountains of New England later this MLK Weekend.

Forecast Snowfall Accumulation from NAM model below:

Forecast Snowfall Accumulation from CAIC-WRF model below:

Have a great weekend!

Post by meteorologist Jim Woodmencey

A Low pressure center on the West Coast has been spinning moisture over both Northern & Southern California the last couple of days. Now it is rotating some of that moisture inland in a stronger Southwesterly flow aloft.

That Low is helping to break down the High pressure that has been parked over the interior of the Western U.S. for the last week.

As this Low-pressure moves inland today (Wednesday) & Thursday it will weaken and be followed by a Ridge of High pressure that will build over the far Western U.S. by later Friday & for Saturday.

SNOWFALL POTENTIAL

The Sierra Nevada Mountains will benefit the most from this storm the next two days. Maps below are from two different computer models, showing 3 to 5 feet of snow accumulation between Wednesday morning and Friday morning (Jan. 16 to 18).

• Sierra Nevada Range will accumulate 3 to 5+ feet.
• Wasatch mountains of Utah could see 1 to 2 feet.
• Teton Range looks to pick up 8 to 10 inches.
• San Juan mountains in Colorado 8 to 12 inches possible.

Another snowfall forecast model below, from the CAIC in Colorado shows a similar picture, for roughly the same time period, Wednesday to Friday morning. This one might have  a little more in certain places than than the NAM.

Good timing for Skiing & Boarding just ahead of the Martin Luther King Weekend!

Post by meteorologist Jim Woodmencey

The big, strong Ridge of High pressure that has been parked over the interior of the Western United States this first week of  the New Year will finally be breaking down today and that will open the door to some Pacific moisture to move inland Sunday & Monday, January 6 & 7, 2019.

Sunday: Warmer Southwest Flow

A moderately strong and moist Southwesterly flow will extend from the West Coast to the Rockies Saturday night into Sunday morning. That flow is out ahead of a weakening Trof of Low pressure that is currently sitting along the West Coast.

That SW flow will be warming temps at all elevations, as valley inversions, like we have seen in Jackson Hole all week, will finally be broken. Snowfall beginning Saturday night and into Monday afternoon across the Northern Rockies.

Snow accumulation from Saturday night Sunday afternoon on map below.

Monday: Cooler Westerly Flow

A stronger Westerly flow will bring a little more moisture inland late Sunday into early Monday. That will bring another shot of Pacific moisture, along with cooler temps aloft….like single digits at 10,000-ft. on Monday.

Total snow accumulation, Saturday night thru Monday afternoon on map below.

USA Snow Accumulation Saturday thru Monday, in video loop below.

Bottom Line is:

The Sierra Nevada range will do best with this weather pattern this weekend, with 2 feet or more at the higher elevations. The Cascades of WA & OR will also do pretty good.

The Tetons & Wind River Ranges in WY , the Wasatch & Bear River ranges in UT & the San Juan mountains of SW CO do good too, with a foot or more of new snow accumulation by end of day Monday.

Back to a weaker, Ridge of high pressure on Tuesday, the way it looks right now.

Post by meteorologist Jim Woodmencey

A good portion of the Rockies and Plains States will be waking up to start the New year with some very cold temperatures. A cold Trof of Low pressure at all elevations in the atmosphere has moved south from Canada in a Northerly flow.

Below is a temperature forecast map for 6:00 AM (Mountain Time) on New Year’s Day. Pink & purple colors represents temps below zero Fahrenheit.

Jackson Hole, WY looks to drop into the teens below zero. Some areas may reach 20-below. BUT! That will depend on cloud cover and wind. Some clouds &/or some wind overnight will  keep temps warmer than forecast. No wind & no clouds and it will reach 20-below.

Cold Up High

Temps are not any warmer up at elevation this last day of 2018, but thankfully they will be warming up the first few days of 2019, with temperature inversions setting up.

It will get warmer up high as it gets colder down low. So, if you are skiing Jackson Hole this New Year’s week, “go up to warm up!”

Forecast map below for the 700mb level in the atmosphere, or near the 10,000-ft. Elevation. Temps in Celsius, 15 below zero C equals +5 degrees F.  So, it could be 20 degrees warmer up high on New Year’s Day in the mountains. (Jackon Hole marked with red dot).

Cold & Windy Last Day of 2018

What Jackson Hole woke up to this morning was very cold air and strong northerly winds. Winds in the valley were over 20 mph and winds on top of the tram were over 40 mph. That made for some brutal wind chills, in the minus 30-degree range at times up at 10,000-ft in the Tetons.

Below are the Temperature and Wind graphs for the past 24-hours (Sunday AM to Monday AM) and a wind chill chart for reference. (Click to expand and print!)

Around 6:00 AM Monday morning the temp at the top of the tram was -2F, with a wind speed of 44 mph, making it feel like it was 33 below zero!

Happy New Year! Stay Warm!

Post by meteorologist Jim Woodmencey