The first Atmospheric River will be cranking over the Sierra beginning Wednesday night. Very strong winds gusts of 60-100 MPH will be evident on the ridges before decreasing on Thursday morning. Temps will migrate from warm Wednesday night with snow falling above 7,000 feet to cooler Thursday and some lake level freshies.
Bottom Line: Very warm initially, cooling Wednesday night and especially Thursday. Very strong winds late Wednesday to daybreak Thursday. Dense snow is expected with this storm. but colder pow coating the surface might make great surf and even a forced face shot. Not upside down (good thing). Wind impacted unless enough new snow falls Thursday morning while the lifts are spinning. You might not get the Mammoth Summit Thursday?
Below: Atmospheric Signature- Warm and wet with temps at 10K feet at -3/-4C (26F). That's only 26 degrees at some peaks and and initially low to mid 30s at 6K. Temps drop on Thursday by daybreak where snow levels lower to near 6K. Winds also fortunately will decrease.
Below: Total snowfall at 10:1 (reasonable) through later Thursday afternoon for the Sierra (10-18 above 9K). Less snow is noted on the eastern side of the lake but most ski areas will all see decent totals through midday Thursday. Peak precipitation will be midnight Wednesday to 10AM Thursday.
Below: U of U ensembles for Kirkwood showing the first AR event in the 18-20 inch range at upper elevations through February 1st (Thursday) and another significant event possible early next week (Slightly cooler).
Below: Extreme winds noted for the Sierra Wednesday night. This map is SUSTAINED at 10K feet (60 MPH sustained).
The AR drops south Thursday for decent odds of a 9-11 inch storm day for Brian Head (A bit less for Eagle Point) Utha, 4-7 for AZB, and significant snow for the Ruby Mountains near Elko, and 7-11 for Lee Canyon (Las Vegas). Disorganized moisture streams north towards Sun Valley Thursday/Friday with 5-10 inches up top and 1-3 inches at the bases (SV is favored by these southerly winds). Bottom Line: You can chase south for some storm skiing on Thursday or gamble on SV further north. Snow quality will be on the dense side, however Brian Head has a 9K base elevation (Big bonus). Sun Valley often scores with AR events pushing north from the Sierra.
The Wasatch grabs disorganized pieces under southerly flow Friday with snow levels at 7K. Expect 3-7 inches on Friday with winds shifting NW behind the front and a cooling trend. This will keep orographic snow showers favoring the Cottonwoods, and areas of the Canyons side of PCMR including Parleys Summit (4-7 additional). Sometimes these pesky southern storms can overperform for the Wasatch so totals by Saturday morning might exceed my forecast. Snow levels trend lower with the entire storm so quality will slowly improve. Timing is not ideal for any single 12-hour dump but Saturday has a chance. Southerly flow on Friday might favor Sundance (Upper elevations) or BCC over LCC. Snow levels start high and slowly drop during the day.
The European models show a decent northward progression of moisture with moderate totals possible for the Tetons and southern Montana. The American shows less (Friday to Saturday). These areas are likely to see less snow than their neighbors to the west or south.
Colorado offers the most questions and overall as a forecaster often poses the most challenges The models seem to be a bit more in synch for the highest totals to land in the San Juan Range (High confidence) on Friday (Storm Ski). This will be a warm storm.
Counterclockwise flow (No real orographics as opposed to moisture streaming overhead) will present challenges on who sneaks out some surprises. Generally, 10-15 inch storm totals are likely above 9,000 feet in the southern San Juan range through late Friday night when the action shifts a bit further north.
Chases? You could start in the San Juan Range Friday and head north for Saturday. Brian Head offers good hope. Telluride might sneak up Friday or Saturday with the wind shift to the NW. The I-70 corridor would be a good staging point as there Is much uncertainty in the models. Consider chasing to Sun Valley (On piste only) Friday or perhaps a bit of storm skiing in the Wasatch . Hang in the Wasatch hoping for better quality Saturday or gamble on the I-70 corridor with higher elevation resorts. The Sierra will be deepest Thursday with new openings possible on Friday
Below: European Model from Friday morning /Saturday showing some decent totals in the southern Mountains of Colorado. Further north offers more questions with a decent chance of the I-70 corridor scoring for late Friday night to midday Saturday. perhaps a higher influence near the Divide. Heavy snowfall is noted near DIA on this map, however, temps are warm so most of this may fall as a rain/snow mix. The Front Range foothills should see snow. There is much that can change between now and Saturday so confidence currently is no better than 50% for the north (Higher confidence south). Our suspicion is driving conditions might deteriorate over Floyd Hill late Friday night and the passes on I-70. Totals for the I-70 corridor might range from 7-12 inches with upper amounts possible near Powderhorn, I-70 from Vail Pass to the Divide (Summit County). Aspen is a solid contender (5-10) with Steamboat a wildcard. WP/Berhoud are all in the hunt here.
Extended: While it might not completely stop snowing in the Sierra this weekend (Snow showers), a perhaps stronger AR event is noted on the models for late Sunday to Tuesday. This system will likely bring another significant storm to the Sierra. Temps will warm with the moisture laden air, but overall looks a bit colder than the storm this week. It may provide a similar track to the storm this week. It's too far out for confidence. We are very confident however, that the storminess will continue.
Below: Low #2 is seen entering the Sierra late this weekend or early next week. There is also a another low entering Canada and the PNW that might bring some light or moderate snowfall to BC or the northern Cascades. by Tuesday February 6th.
Below: Fantasy map of total snowfall for the upper elevations of the Sierra from Tuesday January 30 to Thursday February 8th next week. 30-50 inches are not unreasonable for combined storm totals. Confidence in details is always low this far out, however storm #2 early next week has good hope.
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Enjoy the powder, everyone! Remember, your deepest resort is not always the best chase. See you in the first chair somewhere on Monday.
Enjoy the powder, everyone!
Powderchaser Steve @powderchasersteve on Instagram