Backcountry Avalanche Forecast Central Sierra Nevada This Avalanche Forecast is expired Fund the Forecast Popup (Government funding is not enough) Issued: Thursday, January 19, 2023 - 6:58AM Expires: Friday, January 20, 2023 - 6:58AM Author: Steve Reynaud THE BOTTOM LINE New snow and strong winds have created slabs of wind drifted snow in exposed areas. The new storm snow may have problems bonding to the old snow surface in many locations. Watch for signs of unstable snow, like recent avalanches or cracking in the new storm snow, and move to lower angle terrain if you see instability. Avalanche Danger - See note below for danger on the 19th Friday, January 20, 2023 Above Treeline 3 - Considerable Near Treeline 3 - Considerable Below Treeline 2 - Moderate Saturday, January 21, 2023 2 - Moderate - All Elevations ******************* Althought this is the bulletin for Jan 19 the danger rating is given for Jan 20 and 21 for some reason. To see the danger rating for the 19th it seems necessary to view the bulleting from the 18th: Thursday, January 19, 2023 Above Treeline 2 - Moderate Near Treeline 2 - Moderate Below Treeline 1 - Low ******************* Avalanche Problem #1 Wind Slab Above and Near Treeline, all aspects Likely Small (D1) to Large (D2) Wind slab avalanches continued to be reactive yesterday. Gale force SW winds with gusts over 100mph overnight along with 2 to 8'' of light new snow have built out additional wind slabs on NW-N-NE-E-SE aspects. Winds are forecasted to switch to the NW and eventually to the NE later today and remain strong enough to continue to transport snow. Wind slabs could occur on any aspect in near and above treeline areas. Where these wind slabs form on top of recently buried surface hoar, these avalanches could be wider and run longer distances than our typical wind slab avalanches. Look for recent avalanche activity, blowing snow, cornices, wind pillows, and snow surface clues as to where these wind slabs have formed. Natural wind slab avalanches are not out of the question today. Avoid terrain below steep wind loaded slopes and cornices. Long shooting cracks, whumpfing sounds, recent avalanches with wide propagation, or any sort of remote triggering would indicate that the buried surface hoar is present and reactive. Avalanche Problem #2 Storm Slab Near and Below Treeline, all aspects Possible Small (D1) to Large (D2) 2 to 8'' of new storm snow has fallen overnight with many areas reporting up to 2 to 4’’, additional light snow is possible through this morning. While this amount is on the lower end for storm slab development, this new snow has fallen on now buried surface hoar that developed on Monday and Tuesday nights. Most of the avalanche activity associated with this weak layer should be in the form of loose dry sluffing with these small storm snow amounts. These sluffs could entrain some snow and be able to run downhill long distances at fast speeds. In some of the areas that received the most snow overnight, some small storm slabs could become possible. As this new storm snow begins to settle and gain strength, more slab characteristics may begin to occur. Look for cracking around skis or shooting cracks while moving through terrain. If you see any indication of slab development, utilize lower angle terrain to avoid this problem. Be aware of terrain above and below you, loose dry sluffing could be large enough to take you for a ride downslope in steeper terrain. Forecast Discussion A skier triggered wind slab avalanche was reported from the Ward Canyon area yesterday afternoon. Reports of widespread surface hoar have come in throughout the forecast region on most all aspects and elevations. There is some uncertainty if any of this surface hoar has been destroyed by wind and/or sun pre storm and if this will develop into a persistent slab avalanche problem. Thin sun crusts have started to develop on some sun-exposed slopes. Weather Forecast 2 to 8'' of light snow has fallen throughout the forecast region overnight above 7000'. Chances of additional snow continues for the southern half of the forecast area with some lake effect snow also possible this morning. Gale force SW winds last night switched to the W this morning and should continue to move to the NW and eventually to the NE later today while remaining strong. Cold temperatures 15 to 20 degrees below normal are expected for the weekend. High pressure with sunny skies and temperature inversions will also start to work into our area over the weekend and through next week.