A weak Atmospheric River storm system moved into the region Monday (2/27/17) with 1 to 7” of new snow (greatest amounts new Mammoth and June Lakes) and strong SW winds forming Wind Slabs on NW-N-NE-E-SE aspects. High pressure moved into the region and dominated most of the week with slowly warming temperatures and light winds being the theme, allowing newly formed Wind Slabs time to strengthen and stabilize. As temperatures rebounded through the week small Loose Wet releases in and around rock-bands on solar aspects became an issue, primarily in the low to mid elevations.
The latest storm to impact the Sierra Front began to move into the region late Saturday (3/4/17) with moderate to strong Southwesterly pre-frontal winds (sustained winds of 20 to 30 MPH below ~ 10,000’) with gusts of over 120 MPH along the Crest. With little transportable snow available, isolated sensitive Wind Slabs formed on NW-N-NE-E-SE aspects in the mid to upper elevations on exposed slopes. Sunday (3/5/17), the storm system moved into the region early morning with snowfall rates of 1 to 2” an hour and snow amounts of 1 to 2’ of low-density snow at higher elevations by early Sunday evening. Moderate to strong SW winds during the storm produced extensive sensitive Wind Slabs on NW-N-NE-E-SE aspects throughout the mid to upper elevations with localized eddies and channeling producing Wind Slabs on unusual aspects, potentially extending further down slope than normal, and into typically sheltered areas. Storm Slab potential increased during the height of the storm due to the rapid loading overwhelming the bond between the new snow and the underlying snowpack. Snowfall began to tapper off Sunday evening but Southwest to Westerly winds will continue to transport snow onto Leeward aspects forming sensitive Wind Slabs throughout the mid to upper elevations. Warming temperatures and clearing skies will likely produce Loose Wet releases on solar aspects Tuesday.
Precipitation Totals and Temperatures (4:00 AM, 3/6/17)
Location Snow Water Current Temps
VA Lakes (9445’) 13” 1” 8.6
Tioga Pass (9798’) 12” N/A N/A
Ellery Lake (9645’) N/A .3” 4
June (9148’) 8” .3” 6
Gem Pass (10750’) N/A .6” N/A
Mammoth Sesame St (9014’) 10” .8” 6
Mammoth Pass (9,500’) N/A N/A 7
Rock Creek (9600’) 10” N/A 7
Saw Mill-Big Pine (10200’) 10” N/A 14
Big Pine Creek (10000’) N/A N/A N/A