Warm air that screamed in yesterday will make its exit even more quickly as the front pushes through this morning. The strong cold front is associated with a band of moderate to heavy rain preceding it's passage and may throw a bit of lightning as it over takes the mountains around 8-8:30am. Snow has been melting quickly sending an impressive amount of freewater percolating down into the snowpack. This has been complicated by rain overnight and the impending rapid load anticipated within the next 2 hours. Heavy rain with the frontal passage will increase the stress to an already overburdened snowpack. Both Ravines will likely see their highest instability between 7-10am this morning and therefore potential natural avalanche activity. As the front passes cold air will come rolling in freezing anything wet in its path. The snowpack will freeze from the surface down increasing the tensile strength of the snowpack as the day progresses. Summit temperatures are expected to drop to -12C (10F) by afternoon from their current of 5C (41F). Winds are expected to peak at over 160kph (100mph) this morning before subsiding into the afternoon. Avalanche danger should decrease into the early afternoon as the snowpack freezes from the surface down increasing strength, but a few concerns will still exist. First, rain this morning will likely take a while to percolate down to the crust buried in some deeper locations. Once freewater/rain pools on this crust it will lubricate the interface between it and the slab above. This will possibly delay slab failure and fracture until a while after the rain has ended causing at least some concern until tomorrow. Second, as the front passes 5-7.5cm (2-3in) of snow is possible with the cold air pushing it with high SW and W winds. This "should" initially bond well, but some strong lee areas may pick up significant pockets of new slab. Due to strong temperature gradients we may see these bonds degenerate due to faceting at the interface over the next 24 hours. And third, any new snow avalanche activity has the potential to pull out a much larger wet slab avalanche from the rain soaked snow underneath. All things considered the changes in the stability and the snowpack today are complex and it's probably a better day to tune the skis and sharpen the crampons for the impending hardpack to come.

Be aware of the potential for falling ice until freeze up this afternoon. Falling ice is a hazard on its own and could also trigger avalanches. Lots of changes will occur over the next 24 hours so be sure to check the latest advisory tomorrow morning before heading out into the mountains.

THE LION HEAD WINTER ROUTE IS OPEN. Mountaineering skills and equipment are required for safe travel on this route. The John Sherburne Ski Trail will be wet and soggy early this morning and very challenging later as snow "locks up" with quickly dropping temperatures. You should expect hazards in the form of turf, rocks, bushes and deep waterbars.

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.