Avalanche Advisory Archive Pre-2016

Date Issued:2014-03-06
Danger:1
Trend:3
Probability:0
Size:2
Problem:0
Discussion:

From the National Weather Service Forecast:
Today: Sunny. Highs around 29. Northeast wind 15 to 25 mph near downtown juneau and douglas and out of interior passes. Elsewhere...east wind 5 to 15 mph.

Tonight: Mostly clear. Lows 13 to 21...except around 9 above in wind sheltered areas. Northeast wind 10 to 20 mph.

Friday: Locally windy. Increasing clouds. Snow likely in the afternoon. Snow accumulation to 2 inches. Highs 29 to 35. Northeast wind to 30 mph with gusts up to 45 mph...strongest near downtown juneau and douglas and out of interior passes.

Friday Night: Locally windy. Snow...mixing with rain south of juneau late. Early lows 27 to 35...with temperatures rising slowly overnight. Northeast wind to 30 mph with gusts to around 45 mph...strongest near downtown juneau and douglas and out of interior passes.

Over the last 24 hours temperatures warmed slightly from 15f to 23f. The winds remained blowing up to 25kts throughout the day at the upper elevations.

Over the next 24 hours we will not see much change in the weather other than the temperatures trending slightly warmer, and the winds will be on the rise by tomorrow.

The avalanche hazard remains LOW for this forecasting period with little change in the weather and snow. The potential for large slides that would come close to urban zones and structures is very small.

With temperatures on the rise, warm snow may be an issue especially on wind sheltered, south facing slopes. There is a high spatial variability in the ridge top snowpack above our mega melt-freeze crust, with some faceting existing both below and near the surface of the existing wind slab pockets and remnant snow.

Human triggered slides are still possible in backcountry locations. Watch lee slopes for windslab and southerly aspects for warming snow. If you are sledding or skiing use good travel practices, watch the weather and snow, and make decisions accordingly.

Tip:

Expect tomorrows avalanche forecast to look different with the incoming storm arriving. Here is a link to the NWS Special Weather Statement regarding this storm:
(it can also be found as a headline on the NWS Juneau forecast page)

http://forecast.weather.gov/showsigwx.php?warnzone=AKZ025&warncounty=AKC110&firewxzone=
AKZ025&local_place1=6+Miles+SE+Snettisham+AK&product1=
Special+Weather+Statement#.UxiAtOddWTY

Yesterday we talked about storm snow instability, snow density, and ?upside down? snow. This storm sounds like a great recipe for both of those, then add a hefty dose of wind. Lots of precipitation, high wind, and rising temperatures forecasted throug this storm.

The increasing winds are forecasted to come out of the south east with gusts up to 45kts.

The minimum wind velocity threshold for moving dry loose snow is around 10kts.
20Kts will redistribute large amount of snow on the ground. Higher speeds can easily strip the snow right off ridge tops. Airborne snow needs even lower velocities to move snow as it falls.

While we don't see much dry loose snow in these parts, airborne wet snow is still more easily distributed by the wind while falling. High forecasted wind with this kind of snow means high rates of wind loading on the lee slopes.

Flume and Perseverance trails will be hazardous to travel this weekend, plan accordingly

Forecaster:Peter Flynn