Well here we are in the middle of my favorite classic New England winter storm. It sounds sadistic but I love watching dramatic events like these that swing from rainforest to full Arctic conditions overnight. Every winter we get to witness a day of rain followed by cold air dropping the temperatures by 50 degrees F with a blast of snow at the higher elevations. The summit received exactly one inch of rain by early evening yesterday before temperatures began dropping which changed all precipitation to snow. Snow will continue through the day with temperatures dropping to 0 F (-18C) by this afternoon. Associated with this will be gusty NW winds blowing from 60-80+mph (95-130+kph). We are anticipating 12-18" (30-45cm) of new snow for the higher elevations by midnight! As we went through lock up last night with dropping temperatures the snowpack stabilized very quickly generating "Low" avalanche danger. Snow moving in early this morning has begun ramping up the avalanche danger and as of 7am we feel conditions are at "Moderate". As snow continues and 60-80+ (95-130+kph) winds from the NW create new slabs in both Ravines we will be at "High" avalanche danger by early afternoon. If we move into the 12-18" (30-45cm) range after dark I would expect a few SE aspects to potentially move to "Extreme" briefly before winds pick up in velocity. During the overnight weather models expect winds to be 90-110mph (145-175kph) sustained with temperatures dropping to -10F (-23). The amount of new snow falling and loading will likely insulate the wet snow beneath from freezing rock solid and set us up for enormous temperature gradients. In areas of thin new snow I would expect ideal conditions for rapid facet growth with plenty of moisture moving from the warm wet snow into new cold snow with large porosity. Low density snow with lots of airspace (porosity) allows vapor to move easily which helps facilitate facet growth. It will be fun to watch, but realize it could develop as a significant weak layer over the next few days before getting back to milder temperatures. Beside avalanche problems you will face full Arctic conditions as the day progresses so be ready with good mountaineering clothing. Expect all exposed old surface to be very hard and icy therefore crampons and an ice are absolutely essential on all angled terrain. As the temperature drops climbers should expect "ice dams" to be a hazard, particularly on all gully climbs, for the next couple of days. Hydraulic pressure from the running water builds behind new freezing "ice dams". Sometimes all that it takes is one ice axe swing to release the pressure. Climbers have been seriously injured and worse on Mt. Washington due to this hazard.

THE LION HEAD WINTER ROUTE IS OPEN. Mountaineering skills and equipment are required for safe travel on this route.

The Sherburne Ski Trail is open with varying conditions. Although new snow will improve the experience expect bare ground, water ice, deep waterbars and some running water.

As always, this advisory is one more tool to help you make your own decisions in avalanche terrain. It should be used along with your own snow stability assessments, knowledge of safe travel techniques, skill in reading mountain weather's effect on the snowpack, and avalanche rescue. To improve these skills take an avalanche course. We have all the avalanche courses offered in and around the Mt. Washington Valley this winter on our website, tuckerman.org.