Good Morning backcountry travelers, this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday, February 4, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued 5 days a week Wednesday-Sunday for the Turnagain Arm area (Turnagain Pass is the core advisory area). Local variations always occur.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
-General Weather Observations-
The weather has changed quite a bit from yesterday. Temperatures have warmed up at all weather stations this morning by 7-16 degrees. Ridgetop winds were calm yesterday, but they are starting to increase this morning.
–The DOT weather station near the crest the highway at Turnagain Pass at 1000 feet–
Is recording a temp of 10 degrees (7 degrees warmer than yesterday), calm winds averaging 4 mph from the NE.
–The NRCS Center Ridge weather station at 1800 feet in Turnagain Pass–
Has a temp of 9 degrees (12 degrees warmer than yesterday). Zero new precip. Total snowpack depth is 65″.
–The Sunburst weather station at 3800 feet in Turnagain Pass–
Shows a temperature of 3 degrees (15 degrees warmer than yesterday). Winds have been moderate averaging 11-20 mph out of the ESE since 11pm last night with strong gusts up to 31 mph
-Surface Analysis Maps-
There has been a massive storm out in the Bering Sea for the past couple days. Its starting to calm down a little (950-966mb), but it is still a huge storm that looks like it created a smaller storm that is gaining a little strength (990-986mb) and heading toward us.
On a side note, I saw 40 foot seas on the marine forecast yesterday for places on the Pacific side of the Aluetians.
The Middleton radar shows green and blue precip outside of Prince William Sound but heading our directions. The Kenai radar shows blue and a little green precip over Cook Inlet heading our direction.
Primary avalanche concerns
-Surface wind slabs on alpine ridges
AVALANCHE AND SNOWPACK
Normal Caution is advised for Turnagain Pass, however, there might still be some isolated pockets of elevated caution on really steep convuluted terrain along ridges where you might find windslabs on top of a slipper wind buffed layer.
The main avalanche issues recently have been some very minor, predictable and obvious wind slabs and sluffs in the surface snow. There have been no big changes with that aspect of the snowpack. If you see a pocket of snow that looks fat, then it might avalanche on you; so, either avoid it or know how to manage your terrain.
Its been lots of fun out there, but lets take some time to talk about some future concerns. Just because it is stable today does not mean it will be if we get hit with the right kind of storm. Crusts are bad. They can create bad temperature gradients near them and weak sugary facets like to form above or below crusts. I am very concerned about the bowls along Seattle Ridge because the starting zones for these bowls are below 3000 feet and they have a nasty rain crust under that light fluffy powder that has been skiing so well. We have looked at this crust in Main Bowl, Warm Up Bowl and on Repeat Offender. Temperatures under that crust in Main Bowl had one of those bad temperature gradients; so, we have a serious weak layer to pay attention to in the future.
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST WED FEB 4 2009
.TODAY…SNOW LIKELY ALONG THE COAST. CLOUDY WITH A CHANCE OF SNOW
INLAND. SNOW ACCUMULATION 1 TO 3 INCHES ALONG THE COAST. HIGHS 15 TO
25. EAST WIND 10 TO 15 MPH. WIND CHILLS 5 BELOW TO 20 BELOW IN THE
.TONIGHT…CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS 5 TO
20 ABOVE. LIGHT WINDS. NEAR SEWARD…NORTH WIND 10 MPH IN THE
EVENING BECOMING LIGHT.
.THURSDAY…SNOW. SNOW ACCUMULATION 3 TO 5 INCHES. HIGHS IN THE
LOWER 20S TO LOWER 30S. VARIABLE WIND 10 MPH.
.THURSDAY NIGHT…SNOW LIKELY. LOWS 10 TO 25 ABOVE…COOLEST INLAND.
TEMPERATURE / PRECIPITATION
SEWARD 24 15 33 / 60 40 100
GIRDWOOD 20 14 27 / 40 40 100
This concludes today’s avalanche advisory the next advisory will be on Thursday, February 5th. Thanks and have a great day.