Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Tuesday, November 23rd 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).
All areas designated for snowmachines are still closed. We are measuring the snow in these areas daily and will open them as soon as there is enough snow to protect the ground and vegetation from being torn up by the tracks of a snowmachine. Thanks for your patience.
I’m sure everybody noticed the crazy weather yesterday in the form of freezing rain. The temperature inversion finally broke yesterday morning. We picked up only a small amount of measureable precipitation with the weather stations. Alyeska showed up to .2 inches of rain at the base area. The form of freezing rain is more significant to our snowpack than the amount. We’re starting to get more rain and snow this morning and more is forecasted through the week. Wind in the last 24 hours has been relatively light.
Today the avalanche hazard will be MODERATE. This rating is based on limited field observations. Right now we’re playing catch-up to figure out what is going on with the snow. Yesterday Lisa noticed that the glide crack epidemic seemed to have accelerated. This may be due to the extreme temperature inversion that we had until yesterday morning. Ridgetop weather stations were reporting temperatures into the lower 40s. Sunburst weather station had above freezing temperatures for 66 hours before cooling off yesterday. Our precipitation yesterday was limited, but you probably noticed that it was freezing rain. I don’t think we got enough additional load to cause problems in the middle layers of the snowpack with the absence of significant weak layers. More rain and snow is forecasted for today so the general hazard is on an increasing trend.
At upper elevations pay attention to the wind slab near the ridge tops. This may be sensitive to human trigger, especially as we get more snow load this week.
We’ll have to pay attention to the distribution of the freezing rain layer when we get additional snow. This could be an ideal sliding surface in the future and contribute to instability.
I will issue the next advisory tomorrow morning at 7am. If you get out in the backcountry give us a call at 754-2369 or send us your observations using the button at the top of this page. Thanks and have a great day.
The NWS weather forecast for:
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST TUE NOV 23 2010
.TODAY…RAIN. RAIN MAY BE MIXED WITH SNOW AT TIMES AT HIGHER
ELEVATIONS. NO SNOW ACCUMULATION. HIGHS IN THE MID 30S TO LOWER 40S.
LIGHT WINDS EXCEPT EAST 25 TO 40 MPH THROUGH PORTAGE VALLEY AND
.TONIGHT…RAIN AND SNOW. SNOW ACCUMULATION UP TO 2 INCHES AT HIGHER
ELEVATIONS. LOWS IN THE 30S. LIGHT WINDS EXCEPT EAST WIND 25 TO 40
MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.WEDNESDAY…RAIN AND SNOW. SNOW ACCUMULATION UP TO 4 INCHES AT
HIGHER ELEVATIONS. HIGHS IN THE MID 30S TO LOWER 40S…COLDEST
INLAND. LIGHT WINDS EXCEPT EAST 25 TO 40 MPH THROUGH PORTAGE VALLEY
AND TURNAGAIN ARM.
.WEDNESDAY NIGHT…RAIN AND SNOW. LOWS IN THE MID 20S TO MID 30S.
LIGHT WINDS INLAND. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…EAST
WIND 15 TO 30 MPH DECREASING TO 10 TO 15 MPH AFTER MIDNIGHT.
.THANKSGIVING DAY…SNOW AND RAIN. HIGHS IN THE 30S. VARIABLE WIND 10
MPH EXCEPT NORTH 10 TO 25 MPH NEAR SEWARD.
.THURSDAY NIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS IN
.FRIDAY THROUGH SATURDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW.
HIGHS IN THE 20S. LOWS IN THE TEENS.
.SATURDAY NIGHT THROUGH MONDAY…MOSTLY CLOUDY WITH A CHANCE OF
SNOW. LOWS 5 TO 15. HIGHS IN THE TEENS.
TEMPERATURE / PRECIPITATION
SEWARD 40 36 40 / 100 100 100
GIRDWOOD 38 36 41 / 100 100 80
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Light wind from the east. Temperatures dropped from 42 yesterday morning to the mid 20s where they remain this morning.
-2600′ Seattle Ridge Wx Station-
Recorded the strongest wind speeds in the area with east wind in the teens to lower 20s. The inversion was less pronounced and temperatures have dropped to the high 20s.
-1800′ Center Ridge Wx Station-
Showed only a .1 inch increase in precip. Temperatures dropped to a current temperature of 31. Snow depth continues to settle with anCNFAIC Staff inch lost in the last 24 hours.