Atmospheric River Headed For The West | Some Will Get Snow Others Will Get Rain.

Atmospheric River Headed For The West | Some Will Get Snow Others Will Get Rain.


Atmospheric River Headed For The West | Some Will Get Snow Others Will Get Rain.


Report From

Summary 4/4/18 AM report

It’s not common to see a swath of 3-5 inches of liquid moisture to slam the Sierra in April. Significant rain will be falling over much of the Sierra this weekend with high elevation snow elsewhere. Moderate snow will be falling in the Cascades today eventually teasing Montana with 9-15 inches of pow by late Thursday. Moisture impacts the Tetons and most of Colorado in the extended period with significant snow above 9000 feet. Chasing will be tricky with snow levels your worst enemy unless you head north this week. Late in the weekend may offer your best central Rockies chase (Utah or Colorado). Next week stays wet with the Cascades in the bulls eye of several systems and occasional colder air. Significant rain will fall from the Sierra into the central Rockies below 10,000 feet initially this weekend. Some snow is possible in the Sierra Saturday night at upper elevations.

Short Term Forecast

The previous 2 days has brought an epic April chase leaving Jackson at 4 AM Monday (Raining) and grabbing my first day ever at Big Sky Resort.  It was snowing heavily on arrival (7-9 inches by 8 AM) and even arrived in time for 1st chair with “Brian” the snow reporter for Big Sky.  Conditions were epic Monday with another 4-7 inches during the day, good quality, and  most of the terrain open (Tram shut down at 11:30 AM as well as hike terrain). Tuesday brought a repeat powder day with more variable conditions from winds, and openings of terrain that was closed Monday. Jackson got pounded with 8-15 inches of snow Monday, rain at the base and high winds with variable upper elevations conditions. This is the final weekend for JHMR with high elevation snow in the forecast.

Below: Here is a look from the tram on Tuesday from Big Sky. Everything in the far background was ride worthy especially if you like technical terrain

SYNOPSIS:  Pow will be falling in the central and southern WA Cascades today (Snowing currently) before warmer air moves in late.  If your in WA head out the door now and plan to ski Wednesday after 11 AM (4-8 inches).  Additional snow will fall above 4500 or 5,000 feet tonight. Quality could be chase worthy especially from Stevens Pass and south towards Crystal by early afternoon (Warming late AM).

While most areas of the west warm up, some cold air will be featured in Montana that gets as far south as the Wyoming border this week.  Cold air in the Tetons today (Snowing currently) will bring moderate snow to Jackson and Targhee Wednesday through Thursday morning. Warming over the Tetons will occur later Wednesday so decent quality light snowfall will be prevalent this morning before rain starts falling at the base late Wednesday. Thursday may feature 4-8 inches of dense snow at the summits for 1st chairs or tram. Montana is seeing snowfall today (Light) especially in the north and central regions of the State. Snow will increase slightly tonight and Thursday (locations favored will be from Butte to Missoula). You may see 4-7 inches by last chair Thursday at Montana Snowbowl. Less snow will fall at Big Sky and Bridger (2-4) but will increase late Thursday and Friday.  I am expecting an additional  3-6 inches at the Snowbowl for Friday morning (Storm totals in the 7-13 inch range). The best days to ride will be late Thursday and early Friday. Quality will be decent before a warming trend happens late Friday morning. There will be no single double digit dump in 24 hours. Totals should be decent with the light snow from Wednesday and moderate snow Thursday/Friday.

Big Sky and Bridger, should see another 3-6 inches Thursday night bringing storm totals in the 5-10 inch range by early Friday (2 day totals). Quality will be good with cold air. Best days to ride southern Montana will be Friday morning.

Below: Warm air impacts most areas Thursday night with cold air north of Wyoming (roughly 5500 Feet shown in C). Position of the colder air Thursday night/Friday morning will make significant differences in total snowfall near these lines.

Colorado gets light or moderate high elevation snow on Thursday night/Friday favoring the northern mountains.  Areas that could see the most snow likely will favor areas along or north of I-70. Temps are warm with this storm so the highest totals will be above 9,000 feet.  Models seem to favor Rabbit Ears Pass, and perhaps the Steamboat summit (Very little snow will fall at the base) as well as spots in Grand County (Winter Park).  Its not a significant system, but should offer 3-6 inches for most resorts by Friday morning with isolated pockets of 5-9 inches. I can’t tell you if any of the ski areas actually see the higher end of the forecast totals and hope to narrow it in on my next post.

The atmospheric river impacts the Sierra late this week into the weekend. Significant rainfall is likely in most of the Sierra with up to 4-5 inches of moisture.  Temps stay warm until late Saturday/Sunday. Snowfall is likely at the summits late this weekend favoring the southern Sierra (Mammoth).  These are the types of storms that are not chase worthy from any distance. It’s possible that Sunday morning offer a glimmer of hope for the summits of some ski areas.

Below: Total moisture in the Sierra through late Saturday


Extended Forecast

Significant moisture from the Sierra moves into the Wasatch and most of Colorado this weekend. Temps will keep snow above 10,000 feet initially before dropping to 7500-8,000 feet Sunday. High elevation snow is possible, especially in Colorado with higher peaks this weekend. Rain may be falling at the bases in most areas Saturday before turning to all snow Sunday.  Winds start out from a warmer SW direction before switching to the NW on Sunday. Peak moisture for the Rockies will be late Saturday through Sunday. Moisture and slightly cooler air will be possible in the northern Rockies (Lighter amounts).  Look for a possible powder day on Sunday for most of Colorado (Dense deep snow) and perhaps the summits in Utah or Wyoming.  An unsettled pattern with very moist systems and occasional cooler air will impact the Cascades next week. It’s possible that they score some significant snow from this weekend (High snow levels) through next week (Lowering snow levels at times).  The Panhandle of Idaho may see some colder temps this weekend with a good chance of snowfall near Schweitzer.

It’s going to be a wild ride over the next 7 days!  I can’t pinpoint details this far out but stay tuned for a wet pattern over the next 7 days.

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