Friday, March 28, 2014

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Riding the Spring Wave Train

Well the waves are stacked up in the Pacific and due to some changes in the hemispheric long-wave pattern, they are dropping south and impacting the Sierra. With four different waves forecasted to impact the Sierra in the next 8 days, I think it's time to jump on board the Love Train!

The first wave will impact the Sierra tonight and into early Sunday morning. The crest will see the most snow, with less snow the further east you head (as usual). So we are forecasting 12-18" along the crest and on the west shore, with less snow further east for areas like Northstar, Mt. Rose, and Heavenly (6-12"). We also wouldn't be surprised if some of the highest elevations near the crest see 24" of snow by Sunday morning (Figure 1). 

Figure 1: 24-hour precipitation forecast totals valid tonight through Saturday night.

Figure 2: Mid-level vorticity (measure of spin and instability in atmosphere), winds, and heights. X's and color-shaded areas represent shortwaves/storms. Stacked up across northern Canada and all through the Pacific.

Overall the pattern has shifted in the past week. Ridging and a blocking pattern has developed over the eastern United States, which has helped create more meriodinal (N-S, S-N) flow over the western United States. This has allowed that 'backdoor' cold air to slide south out of NW Canada as we have seen in our previous winter storms this year. Additionally, a ridge has developed further west in the northern Pacific than it normally has this winter, and is not quite as strong as it has been. This has allowed an active Pacific to move troughs up and over the ridge and back down south to the California coast with some help of the cold Canadian air (Figure 2).

Figure 3: Precipitable water valid tomorrow morning

The first wave will move through tomorrow, but good moisture advection with southwest flow ahead of the trough will start producing precipitation this evening and overnight (Figure 3). There is a better moisture connection with this storm than the previous one and the moisture connection will be better than the two waves early next week.

Figure 4: 5-day forecasted precipitation totals. 2-5" expected in the Sierra by Wednesday morning.

Overall, we are looking at 1-3" of precipitation from tonight to Sunday morning (Figure 1). However, some of the higher precipitation totals will be at lower elevations. The snow level will begin around 7000' and drop tomorrow to around 5000' by tomorrow afternoon.

We will have a break in the snow late Sunday morning through Monday afternoon before the snow starts up again. There will be two shortwaves the impact the Sierra Monday night and again Tuesday night. As of now, we are forecasting 4-8" for the first wave (Monday PM - Tuesday AM) and 3-6" for the second wave (Tuesday PM - Wednesday AM). So by Wednesday morning we should have another 7-14" of snow.

It should be some fun riding over the next week with the wave train coming through, albeit a late wave train. So enjoy it while its here and stop wishing it didn't come 2 months ago! We will get some nice winter riding in and this will extend our spring skiing further into April. Ride the train!!!


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