City and Borough of Juneau
155 S. Seward Street
Juneau, Alaska 99801
tel. 907-586-5240
fax 907-586-5385
http://www.juneau.org

Urban Avalanche Advisory

Current Advisory as of Wednesday, April 16, 2014

Expires 7:00am on Thursday, April 17, 2014
Issued by Chris Eckel


Avalanche Danger Level 1

Click here for danger definitions

Avalanche Trend Level 3Avalanche Size Level 1

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Today's Discussion

TODAY ... MOSTLY CLOUDY. SLIGHT CHANCE OF RAIN. HIGHS AROUND 48. SOUTHEAST WIND 10 MPH.

TONIGHT ... MOSTLY CLOUDY. CHANCE OF RAIN. LOWS AROUND 37.
NORTHEAST WIND 5 TO 15 MPH.

THURSDAY ... CHANCE OF RAIN IN THE MORNING...THEN RAIN IN THE
AFTERNOON. HIGHS AROUND 49. NORTHEAST WIND 10 MPH SHIFTING TO THE SOUTHEAST IN THE AFTERNOON.

Precip has been nominal and winds have remained out of the SSE for the last 24hrs. Temps at the tram have not dropped below freezing since 9am on 4/12, they are currently 2c. This has helped contribute to the 12cm of settlement and consolidation that has also taken place at the Tram since the morning of 4/12.

This weather is representative of the lower half of our urban start zones. The upper portion of the start zones is likely seeing a little more of a diurnal change with a nightly freeze/thaw cycle.

Precip amounts should be light with this first storm, with rain during the day, and snow at night in the start zones.

Main avalanche problem continues to be point release wet slides that can entrain until they run out of snow on the way down. These are unlikely to cause problems in developed areas. The possibility for larger wet slabs exists but is not likely in our urban zones at this time.

The avalanche danger is LOW today. Remember to minimize exposure in avalanche run-outs in the heat of the day when wet slides normally occur.

Today's Avalanche Tip


DIURNAL TEMPERATURE VARIATION

Diurnal temperature variation is a meteorological term that relates to the variation in temperature that occurs from the highs to the lows during the day.

Diurnal temperature variations are greatest near the earths surface.

High desert areas typically have the greatest diurnal temperature variations. Low lying, humid areas like Juneau AK, typically have the least. This explains why an area like the Snake River Plain can have high temperatures of 38 C (100 F) during a summer day, and then have lows of 510 C (4150 F). At the same time, Washington D.C., which is much more humid, has temperature variations of only 8 C (14 F); Hong Kong has a diurnal temperature range of little more than 4 C (7 F). Charaa, Bolivia averages a DTR of 50 F (28 C) in July, while Hayfork, California averages 48 F (27 C) in August.

The Montana Department of Environmental Quality claims the World Record diurnal variation was in Loma, Montana which had a variation of 103 F (57 C) (from -54 F (-48 C) to 49 F (9 C) in 1972.

This Advisory applies to the Mt. Juneau Avalanche Zones



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