Turnagain Pass

Good morning. This is Graham Predeger with the Chugach National Forest Avalanche Information Center on Tuesday, January 10th at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

BOTTOM LINE

The avalanche danger is CONSIDERABLE this morning and may trend towards HIGH as this most recent storm intensifies throughout the day with increasing precipitation. Human triggered avalanches will be likely with the increased load of new snow forecast and fresh wind slabs.

AVALANCHE DISCUSSION

If you were out in the backcountry yesterday, it was hard to believe that an intense winter storm was headed our way. Monday’s brief high pressure is giving way to blizzard like conditions throughout the advisory area today. The National Weather Service states “An impressive plume of moisture is associated with this system reaching back to the subtropics.” This satellite image sums it up nicely.

The primary avalanche concern today will be quite obvious. It is arriving in the form of high winds and periods of intense precipitation throughout the day. This will be our first big wind event since December 20th. We have ample snow on the ground available for wind transport, coupled with subtropical moisture streaming into the advisory area. This is a red flag for heightened avalanche activity. Remember, MOST AVALANCHES OCCUR DURING OR WITHIN 24 HOURS OF A STORM. We will be well within that window all day today and most likely tomorrow as well.

A secondary concern that is worth mentioning is the widespread rime crust that was deposited on January 7th/ 8th in the Turnagain Pass region. It is still too early to tell if this fragile crust will act as a weak layer for subsequent slabs to run on or if it will be obliterated by today’s winds. We will be watching closely to see how it reacts to the increased snow and wind loads over the coming days.

MOUNTAIN WEATHER

Winds began to increase into the moderate range around 8pm last night with approaching high clouds from the southeast. As of this morning winds are already in the 50-60 mph range with gusts approaching 90 mph at the Sunburst weather station. There is a blizzard warning in effect for the Girdwood and Turnagain pass regions until 9pm this evening.

Snowfall in the advisory area is just beginning as of 6am and looks to intensify as the day progresses. There is still some uncertainty as to the amount and timing of the heaviest precipitation, but we can expect favored areas in the eastern Turnagain arm region to receive upwards of 24″ of snow by the time this low passes Wednesday night and into Thursday.

Temperatures are still relatively cool this morning though forecast to rise into the mid 20’s today. At this point, it appears that temps will stay below freezing at 1000′ as this low pressure moves through on an east to southeast flow across the Chugach range.

CNFAIC Weather Page and the NWS forecast

Kevin will issue the next advisory Wednesday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.