Good Morning backcountry travelers, this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday, January 14, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued 5 days a week Wednesday-Sunday for the Turnagain Arm (Turnagain Pass is the core advisory area). Local variations always occur.
The Anchorage School District closed school due to icy roads. Please be careful driving today.
Huge thanks to AK DOT for getting the weather station at mile post 69.9 running. That is the weather station you seen along the highway on the motorized side just before the crest of Turnagain Pass.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
-The Center Ridge weather station at 1800 feet in Turnagain Pass-
No data. We will be helping NRCS to finish repairs. The good news is that all the data for the past month has been logged it just hasn’t transmitted; so, once it is back online, we will be able to update our snowfall and temperature records.
-The DOT weather station at 1000 feet on the motorized side of Seward highway-
Is reporting a temp of 35 degrees (9 degrees warmer than yesterday), winds averaging 9 mph out of the NE with a gust of 19 mph. About 7 inches of new snow has been recorded.
-Sunburst weather station at 3800 feet in Turnagain Pass-
Recorded light to gale force winds averaging 12-44 mph from the E with gale force gusts to 71mph. Current temperature is 26 degrees F (7 degrees warmer then yesterday)
-The Grandview weather station at 1100 feet along the railroad tracks-
Recorded 0.3 inches of water and 0 inches of new snow. Current temp is 33 degrees F (6 degrees warmer than yesterday)
-Surface Analysis Maps-
From 3 am Tuesday to 9pm last night…
A strong storm centered south of the Aluetians has slowly been moving NE towards us and getting slightly weaker (964-966mb). The outer arm of this storm is directly over us.
The analysis from 9pm last night shows the firehose pointed right at us flowing south to north. The forecast calls for it to stay about the same for the next couple days. Its not a full-on pineapple express, but it should bring lots of warm air toward us.
As of 5:30 am this morning…Shows a lot of moisture moving quickly up from the south towards us.
The Middleton radar shows a massive green monster of precip over Prince William Sound moving south to north. The Kenai radar shows lots of green precip over Anchorage and the Kenai Mountains.
-General Weather Observations-
Compared to yesterday…Temps are warmer at all weather stations by 6-18 degrees. Winds have been strong to gale force at all weather stations with gusts as high as 71 mph. The National Weather Service has issued a High Wind Warning today. There is a lot of precip heading toward us.
PRIMARY AVALANCHE CONCERNS
-Wind slabs on top of December facets
-New storm snow on top of December facets
SECONDARY AVALANCHE CONCERNS
-Glide Cracks (see photos)
WATCH OUT SITUATIONS
-Terrain under or near avalanche run out zones and terrain steeper than 25 degrees.
AVALANCHE AND SNOWPACK DISCUSSION
Avalanche terrain will be dangerous today. It will be very likely that you will trigger an avalanche on steep terrain or a natural avalanche might come down on top of you down in the flats. Traveling in avalanche terrain is not recommeded today.
We went up Tincan yesterday at the beginning of this storm to see how the facets were reacting to the new snow on top. About 5 inches of snow fell on Sunday night and more snow and wind was building yesterday. A CNFAIC observor reported some sensitive slabs on Eddies on Monday. Our observations from Tincan yesterday showed more signs of poor stability. We found sensitive wind slabs on steep test slopes and poor stability underneath that sugary snow that formed on the surface since Christmas. Our stability tests found easy, clean, and fast shears (they were not Q1’s but they were really good Q2’s). Yesterday, we triggered very small and shallow avalanches and we saw a very small natural avalanche near Kern Creek. There will be an increasing trend for larger, deeper and more destructive or potentially fatal avalanches today.
This is the first big storm to hit us after a couple weeks of cold weather. The snowpack does NOT abide with this kind of aggression.
Temps are still cold enough from mid elevations to the ridgetops for snow to build on top of that weak sugary snow. Winds are forecasted to remain very strong. All the weather observations this morning indicate that we are in the line for more heavy weather today.
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST WED JAN 14 2009
…HIGH WIND WARNING IN EFFECT FROM 9 AM THIS MORNING TO 1 AM
AKST THURSDAY FOR TURNAGAIN ARM AND PORTAGE VALLEY…
.TODAY…RAIN…HEAVY AT TIMES. HIGHS IN THE MID 30S TO LOWER 40S.
EAST WIND 15 TO 30 MPH EXCEPT EAST 35 TO 50 MPH INCREASING TO 55 TO
80 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM IN THE MORNING.
.TONIGHT…RAIN…HEAVY AT TIMES IN THE EVENING. LOWS IN THE 30S.
EAST WIND 15 TO 25 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN
ARM…SOUTHEAST WIND 60 TO 80 MPH DECREASING TO 40 TO 55 MPH AFTER
.THURSDAY…RAIN. HIGHS IN THE MID 30S TO LOWER 40S. SOUTHEAST WIND
15 TO 20 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…SOUTHEAST
WIND 20 TO 35 MPH BECOMING EAST AND INCREASING TO 40 TO 55 MPH IN THE
.THURSDAY NIGHT…RAIN. LOWS IN THE 30S. SOUTHEAST WIND 15 TO 25 MPH.
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…EAST WIND 40 TO 55 MPH
DECREASING TO 25 TO 40 MPH AFTER MIDNIGHT.
.FRIDAY…RAIN. HIGHS IN THE MID 30S TO LOWER 40S. SOUTHEAST WIND 15
TO 30 MPH EXCEPT SOUTHEAST 40 TO 55 MPH THROUGH PORTAGE VALLEY AND
TEMPERATURE / PRECIPITATION
SEWARD 36 35 37 / 100 100 100
GIRDWOOD 37 35 38 / 100 100 80
Thanks for checking the CNFAIC avalanche advisory. Have a great day.