Monday, December 29, 2014

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Inside Slider

We have a nice classic inside slider coming down the eastern slope of the Sierra tonight and tomorrow. Very cold air accompanies the inside slider, but not very much moisture due to the continental (versus marine) nature of the wave. Snow will begin late this evening and continue into tomorrow morning along the Sierra crest and east and pushing all way down past the southern Sierra (Figure 1). 

  • 1-3" of snow along and near the Sierra crest
  • 2-6" of snow for the eastern Sierra and western mountain ranges in Nevada (i.e. Mt. Rose)
  • Very cold temperatures and powdery snow are expected

Figure 1: Snowfall amounts tonight and tomorrow morning. Graphic via NWS Reno. 

Northwest flow across the Sierra relinquishes to a wave digging south to southwest along and over the Sierra today through tomorrow (Figure 2). The term inside slider describes this storm track due to the south-southwest trajectory of a storm from the inland Pacific Northwest to along or just east of the Sierra. These storms are usually colder and drier due to their origination (inland) away from the modification or moisture of the eastern Pacific. Additionally, these storms usually bring more snow east of the Sierra crest than west due to the upslope flow residing on the east side. 

Figure 2: A wave moves from the inland Pacific Northwest back along and over the Sierra over the next 24 hours. This storm track is often referred to as an inside slider, which brings more snow east of the Sierra crest than west. 500 hPa or mid-level winds, temperature, and heights. Image via CEFA/CANSAC.

A strong cold front accompanies the inside slider, which will bring north to northeast winds to the Sierra and eastward as it passes through tonight (Figure 3). By tomorrow morning, winds transition to east-northeast. The very cold temperatures and upslope flow will provide the necessary lifting for snow, but the snowfall will be limited due to the lack of moisture. The snow will be very dry and therefore more powdery than we have received this season. 

Figure 3: A cold front pushes through tonight (8pm-4am). 700 hPa or 9,000-10,000' winds, temperature, and heights. Image via CEFA/CANSAC.

So chalk a win up for the Carson Range and the eastern Sierra tonight and tomorrow. We could see some dust on crust scenarios with recent warm conditions and limited snowfall. However, with new snowfall and persistent cold temperatures for the rest of the work week, the conditions should be enough to get you up on the mountain, hungover or not. 

Happy New Year! 


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