This advisory expires at midnight Wednesday, 2-29-2012
Tuckerman Ravine currently has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
Huntington Ravine currently has LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
On this final day of February, in a leap year, the Snow Rangers are celebrating an extra day of winter with the hope it will help our annual snow total. Wishful thinking you say? Well read on to hear about the impending storm moving in today. Over the past 24 hours the summit only received 0.3” of new snow with moderate NW winds which obviously didn’t add to many avalanche instability issues. All areas dropped a rating from yesterday with the main concerns living in the Center Bowl, Lip, and Sluice. The fracture lines from last weekend’s storm continue to slowly fill. This aids us to quickly determine how much these general areas are picking up with a quick look through the binoculars. Overall, there are some instabilities to recognize today, but the real problems won’t develop until very late in the day with the intrusion of our next weather maker. A WINTER STORM WARNING is in effect from 7pm tonight to 9pm Thursday evening. The system moving from the S will give us a chance of afternoon snow before the main precipitation shield envelops the mountains. Snow totals are expected to be heaviest in the southern part of the state where a QPF (expected water equivalent) of 1.0” is higher than the 0.7” for our region. One thing the North Country has going for it is colder air, adding to our “fluff factor”, as the NWS calls it. In total 6-10” of snow is a reasonable expectation by the time it shuts down. This storm will be delivered on light to moderate S to ESE wind from 10 to 40+ mph. This won’t have the usual loading factors we see with our prevailing westerly’s so expect Hillman’s Highway, Left, the Escape Hatch, South, and Odell gullies to be our main forecast areas of concern tomorrow. We will have cross loading issues in some areas, but that will be greatly determined by how high our wind speeds become. Although the weekend is still many weather model runs away, they currently are highlighting some shifting and increasing wind which are concerns for me. Winds are expected to stay light to moderate, for Mount Washington, until Saturday when a W or NW will may hit +/-80mph overnight giving us a significant loading event. More on this potential avalanche issue in the upcoming days.
Summarizing, in areas at Low danger you will find old surface with numerous pockets of softer snow which can be easily avoided by a skier, rider or climber that’s paying attention to the terrain. Areas at Moderate harbor more issues due to the last 3 days of loading and 1.7” of snow. The winter storm will start giving us snow this afternoon but should not affect avalanche danger today during daylight hours if the forecasted timing is on the mark. Be ready to adjust your plans if it begins earlier than very late today. The intensity will pick up during the early morning hours with up to a few inches on the ground by dawn. Snow will fall through Thursday increasing the avalanche danger. Expect “Considerable” or higher to be issued in tomorrow’s advisory.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856