Good Morning backcountry travelers, this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday, January 7, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued for the Turnagain Arm (Turnagain Pass is the core advisory area). Local variations always occur. Note: We issue advisories 5 days a week Wednesday-Sunday.
There have been reports of skiers and snowmachiners getting deep frost bite on their toes and faces over the past couple days. Please be careful with these super cold temps.
We would like to give a huge THANK YOU to the latest batch of CNFAIC Observers, Blaine and Nancy from the Alaska Avalanche School, and the Friends of the CNFAIC for a great weekend of avalanche observer training. Braving the freezing cold temps really shows your commitment to the local mountain community. We look forward to your future observations. Thanks again.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
-The Center Ridge weather station at 1800 feet in Turnagain Pass-
Still no data. Hopefully it will be back up and running early next week thanks to the Natural Resources Conservation Service. Those guys are awesome. They keep most of the SNOTEL weather stations running around Alaska.
-The Grandview weather station at 1100 feet along the railroad tracks-
Recorded 0 inches of water or new snow. Current temp is -14 degrees F (3 degrees colder than yesterday)
-Sunburst weather station at 3800 feet in Turnagain Pass-
Recorded calm to light winds averaging 0-9mph from the W with light gusts to 13 mph. Current temperature is 2 degrees F (4 degrees warmer then yesterday)
-Surface Analysis Maps-
From 3 am Tuesday to 9pm last night…
Show several low pressures in the area, but none of them look like they are doing much. Its kind of weird that there has been a low pressure just south of Prince William Sound over the past couple days, but you’d never know it by the clear cold weather we’ve been having. A new storm has developed south of the Aluetians that has been building (998-976) and moving in a NE direction.
The analysis from 9pm last night showed the main flow is still to our south flowing west-east toward British Columbia and Washington. The forecast does not call for any major change in that pattern until Sunday when it is predicted to shift and flow south to north from Hawaii toward us.
As of 5:30 am this morning…Shows that it is perfectly calm and things are moving very slow above us. You can also see that new storm south of the Aluetians.
There is actually some light precip south of Prince William Sound hitting the southern tip of Montague Island.
-General Weather Observations-
Compared to yesterday…Temps from sea-level to ~2500 feet are getting colder by 3-5 degrees. Portage is negative 28 and Girdwood is negative 13. Ridgetop temps are getting warmer this morning by 4-9 degrees. Winds have been very calm to light.
PRIMARY AVALANCHE CONCERNS
-Faceted surface snow
SECONDARY AVALANCHE CONCERNS
-Glide Cracks (see photos)
-Small and shallow wind slabs near ridges
WATCH OUT SITUATIONS
-The next storm or wind event
AVALANCHE AND SNOWPACK DISCUSSION
We have a grab bag of weak layers near the surface that WILL become a problem when the next big storm comes in….
-This cold weather has created a bad temperature gradient in the top 1-2 feet (~40cm) of snow. Recent snow temperatures taken on Sunburst, Main Bowl, Magnum, and Lipps show conditions favorable for the formation of facets. Plus, we have seen small facets through our magnifying glasses in the surface snow. Basically, this means that a bad weak layer is forming in the current surface snow. This weak layer is everywhere. That means all aspects and elevations.
-The recent clear weather, calm winds and cold temps have created surface hoar from the highway to the ridgetops in certain areas. The biggest surface hoar is found at low to mid elevations up to about 2800 feet.
These facets that formed on the ground in October continue to show signs of improved stability. This layer, however, is still a concern for future avalanches, especially during and after the next big storm.
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST WED JAN 7 2009
.TODAY…SUNNY. PATCHY MORNING FOG. HIGHS 5 BELOW TO 10 ABOVE. NORTH
WIND TO 10 MPH EXCEPT NORTH 25 MPH NEAR SEWARD AND WEST TO 20 MPH AT
.TONIGHT…CLEAR. LOWS ZERO TO 10 BELOW. NORTH WIND TO 10 MPH EXCEPT
NORTH 25 MPH AT SEWARD AND WEST TO 20 MPH AT WHITTIER.
.THURSDAY…PARTLY CLOUDY IN THE MORNING…THEN MOSTLY CLOUDY
WITH ISOLATED SNOW SHOWERS IN THE AFTERNOON. HIGHS 5 BELOW TO
5 ABOVE. NORTHEAST WIND 10 TO 15 MPH WITH GUSTS TO 30 MPH.
.THURSDAY NIGHT…CLOUDY WITH A CHANCE OF SNOW. LOWS 5 BELOW TO 10
TEMPERATURE / PRECIPITATION
SEWARD 6 -2 10 / 0 0 20
GIRDWOOD -2 -8 2 / 0 0 20