Less is More…..
Update as of 6 p.m.:
Resorts around the lake reported around 2 feet on top and a foot at the base last night. Most of the snow fell in about a 6 hour period as the cold front went through, with snowfall rates of 2-3 inches per hour. I saw snowflakes the size of baseballs around 6 p.m. Reports at lake level range from 4-15 inches based on location and elevation.
Attention now turns to the weekend. The block over the Aleutian Islands will shift Southeast and therefore will shift the low pressure that you see spinning on satellite in the Gulf of Alaska to the Southeast. This will bring the jetstream into Northern CA by Friday. The snow levels will start off well below lake level as the snowfall moves in by Friday afternoon. By Saturday morning we should see 3-6 inches at lake level and 6-12 inches above 7000 ft. On Saturday the core of the jetstream pushes through along with the heaviest precip. With a storm like this we would normally see the snow levels rise to 8000-9000 ft. The thing we have going for us this time is that the polar jetstream will be merging with the subtropical jetstream and the fetch across the Pacific is not as far South as a warm “Pineapple Connection” would be. Also, my less is more theory is based on the fact that the trend has been to push the jetstream and heaviest precip to our South which puts us on the colder side of the jet. Less precip but more of it is snow. You can see on the 5 day precip forecast on the sidebar that the bullseye is to our South. During the heaviest part of the storm on Saturday we should see the snow levels rise to around 6500 to 7000 ft. That still keeps the majority of the resorts terrain as all snow. It looks like it will rain at lake level for a time Saturday, but unless you plan on skiing on the shore of the lake or downtown who cares?
Saturday night into Sunday the snow level drops back down to lake level as the cold front approaches. The cold front will bring another round of heavier snow. Total liquid by Sunday night over Tahoe looks to be in the 4-5 inch range right now, with up to 6 inches on the crest. Snowfall rates on Saturday could be 2+ inches an hour all day. With snow ratios of 10:1 and a little higher on Sunday that means we should see 4-6 feet of total snowfall where it stays all snow above 7000 ft. In the 6500-7000 ft. range where it may mix or change briefly to rain it would be more in the 3-4 foot range. At lake level we should see 1-2 feet which mostly falls on Sunday with the passage of the cold front. On the crest spots could break 6 feet, especially on top of the resorts above 8,000 ft. Avalanche teams should be busy with the multiple layers we are building. The thick we base we had froze last night, then we received 2 feet of fluffy powder last night, more powder Friday, then feet of heavy wet snow Saturday before we top it off with a foot or two of powder on Sunday. The snow levels are not etched in stone so I will update them the next 2 days as well as the snowfall amounts if they change. I would expect periods of closure over I-80 over the weekend with a storm of this magnitude.
On Monday we should see the snow continue with colder air and a moist flow in place creating snow shower. Attention then turns to the next big storm for Tuesday. The trend for this storm has been further South as well. We may see a similar event to that of this weekend, with similar snow levels and precip amounts. The Euro model however did have the storm so far South on the latest run that we only see a foot or two of additional snow. We will have to watch the track over the next several days. The potential exists for the resorts to receive enough snowfall over the next week to reach 50% of their annual average before Christmas. I will be showing this daily on the Resort Totals page over the next week.
By the middle of next week it looks as if the blocking high pressure wants to shift West again to the same position as this past week. That will turn the jetstream to our North again. We should see milder and drier weather the end of next week into the Christmas weekend. There could be a stronger storm that shifts the jet into Northern CA briefly the day after Christmas bringing a return of snow. We should then see it shift back to the North again. As you can see on the sidebar the MJO is dying over the Maritime Continent so it most likely will not be able to help us continue storminess through this period as we were hoping.
By the end of the month the Blocking high pressure over Greenland should weaken according to the NAO forecast that is trending positive. This would shift the pattern in the Pacific back to the East and return the jestream to the Pacific NW and CA by the end of the month. In a typical La Nina the blocking high should be South of Alaska and not over the Aleutian Islands. That brings the trough down along the West Coast along with colder air and the jetstream underneath the block into the Pacific Northwest and Northern CA. This is what I would expect for January and February. The jetstream is also very strong this year so we should see colder air along with lots of storms for the heart of winter. Stay tuned……..BA
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