The National Weather Service Forecasts-

TODAY...MOSTLY CLOUDY. LOCALLY WINDY. SLIGHT CHANCE OF SNOW IN
THE AFTERNOON. HIGHS 27 TO 33. EAST WIND 10 TO 15 MPH...EXCEPT
EAST WIND 20 TO 30 MPH WITH GUSTS TO AROUND 45 MPH OUT OF
INTERIOR PASSES...INCLUDING DOWNTOWN JUNEAU AND DOUGLAS.

TONIGHT...MOSTLY CLOUDY. LOCALLY WINDY IN THE EVENING. SLIGHT
CHANCE OF SNOW LATE. LOWS AROUND 28...RANGING TO AROUND 8 IN THE MENDENHALL VALLEY. EAST WIND 10 TO 15 MPH...EXCEPT 15 TO 25 MPH WITH GUSTS TO AROUND 40 MPH OUT OF INTERIOR PASSES THROUGH MIDNIGHT.

FRIDAY...MOSTLY CLOUDY. LOCALLY WINDY. CHANCE OF SNOW IN THE
AFTERNOON. HIGHS 22 TO 32. EAST WIND 10 TO 15 MPH...EXCEPT 20 TO 30 MPH NEAR INTERIOR PASSES.

FRIDAY NIGHT...MOSTLY CLOUDY. LOCALLY WINDY. CHANCE OF SNOW.
LOWS 17 TO 27. EAST WIND 10 TO 15 MPH...EXCEPT 20 TO 30 MPH NEAR INTERIOR PASSES.

If we are lucky we will see just enough new snow to help Santa's sleigh ride!

With the warm weather from 2 weeks ago, the rain and heavy dense snow, the lower snowpack has settled and bonded quite a bit.

There are still multiple weak layers lower in the snowpack but the heavy dense snow above them appears to be supportive at this time. Be cautious as new loads are placed on these already weak layers by new snow or even by additional wind loading.

Look to see continued areas of wind loading as the snow in place is affected by winds of 10+ MPH throughout most of the next few days.

Last Thursday natural avalanche releases were sighted on multiple aspects due to wind loading. Be aware there are pockets of instability.

With very little snow on Mt Juneau in the urban starting zones avalanche danger is LOW at this time. Yet some of the gullies are starting to see fair snow accumulation due to crossloading from the winds.

Remember- Long periods of cold temperatures build weaker snow, which isn?t a problem until the next significant snowfall.

When temperatures stay well below freezing for long periods of time and high and low temperatures never rise above 15?F (-10?C) day and night, weak layers may develop on the surface or near the ground in a shallow snowpack; this can create a weak layer that fails with the next load of new snow.

Please remember this is not a Backcountry Forecast-
Backcountry danger levels could be considerably higher.

Let see if we can put the knowledge we gained in the last weeks tips section to good use.

Use the following data to create your own avalanche forecast:

You?re forecasting for a highway corridor in south-central Alaska where several south-facing avalanche paths impact the road. The starting zones are at approximately 3,000 feet (900 meters) and the road is just above sea level. Slope angles in the starting zones average around 40 degrees.

It?s been a snowy winter(you can tell this is practice, oh well!). From the third week of November through December, the area was hit with a continuous series of storms, bringing snow down to near sea level. By the end of December, settled snow depths were about 5 feet (1.5 m) between 2,000 and 3000 feet (600 and 900 m).

It rained on January 1 up to near 3,000 feet (900 m). This was immediately followed by several days of high pressure, cooler temperatures (15?F to 25?F, -9?C to -4?C), and northerly winds of 30 to 50 mph (13 to 22 m/s). Clouds increased and temperatures warmed up to 30?F (-1?C) at 3,000 feet (900 m) by the end of the first week in January.

During a five-day period in the second week in January, a series of storms brought more snow to the area.

?They began with warm, southwesterly flow and temperatures around 30?F (-1?C) at 3,000 feet (900 m)

?The winds turned southeasterly at the end of the period, with temperatures around 25?F (-4?C)

?Ridge-top winds averaged between 30 and 40 mph (13-18 m/s) throughout the storm period

?The five days of storminess produced 3 feet (1 m) of snow and a little less than 3 inches (76 mm) of water at 2,500 feet (750 m)

?The average snow density was around 10%

What type of avalanche climate does the area have? (Choose the best answer.)
a) Continental .
b) Intermountain .
c) Maritime .
The correct answer is C.

The deep snowpack, frequent storms, and occasional winter rain give the area a maritime avalanche climate.

2. How would you characterize the overall snowpack between 2,000 and 3,000 feet (600 and 900 m) just after January 1? (Choose the best answer.)

a) Shallow and relatively weak .
b) Deep and relatively strong .
The correct answer is B.

The five feet (1.5 m) of snow in December and almost continuous storms in January built a consistent snowpack.

3. During the first week of Janaury, what type of layer formed on the snow surface in the starting zones? (Choose the best answer.)

a) Near-surface facets .
b) Rain crust .
c) Sun crust .
The correct answer is B.

Rain to almost 3,000 feet (900 m) on January 1 was followed by a hard freeze, causing a rain crust to form.

4. Could surface hoar or near-surface facets have formed on the southerly aspects just prior to the storms during the second week of January? (Choose the best answer.)

a) Yes .
b) No .
The correct answer is B.
It was windy when it was coldest, which inhibited surface hoar growth. There were no new snow crystals on top of the hard frozen rain crust that could become faceted. It warmed up to near freezing before the next storm.

5. Which slope aspects were most likely to be wind loaded during the storms that occurred in the second week of January? (Choose all that apply.)

a) Southwest .
b) Northeast .
c) Northwest .
d) East .
e) South .
The correct answers are B and C.

Winds were first out of the southwest, then southeast. Thus, the northeast- and northwest-facing slopes were leeward.

6. Would you expect avalanche potential to be high on south-facing slopes (those that threaten the highway) after the last series of storms? (Choose the best answer.)

a) Yes .
b) No .
The correct answer is B.

South-facing slopes were windward. Other than some possible cross loading, most of the wind loading went to the opposite side of the ridge. Three feet (1 m) of snow over five days increased the danger some yet was probably insufficient to increase avalanche potential a lot. Densities stayed good through the storm.

This low-elevation coastal mountain range has a maritime avalanche climate. It had a relatively deep snowpack, by lower 48 standards, (5 feet or 1.5 m) by the end of December. We can assume that the pack was strong based on its depth and the storms that hit the area continually from late November through December. This prevented crusts from forming on top of the pack and weak layers from forming within it.

The rain on January 1 may have caused some avalanching but it would have stopped when the cold air arrived and froze the surface snow. In addition, the rain that percolated down into the upper snowpack would have frozen, increasing the strength of the pack. Overall, January began with a strong snowpack. The only worrisome layer was the rain crust, which could provide a good sliding surface for any new snow. However, the high northerly winds prevented any weak layers from forming on top of the crust during the cold period. In addition, the warming temperatures would have sublimated any surface hoar that might have formed on south-facing slopes.

The storm began to warm but it?s questionable if the snow could have bonded with the crust if the snow remained relatively cold and hard. The potential for direct-action avalanches would have been higher on south-facing slopes if the three feet (1 m) of snow had accumulated faster or if the storm had been upside-down(warming throughout placing heavy dense snow on top of looser lighter snow). Since the snow fell at relatively warm and consistent temperatures over the five-day period, it probably had time to settle and bond. The storm also finished right-side-up with slightly cooler temperatures and lower-density snow. In addition, the wind direction during the storm was not favorable for loading the south-facing slopes since they were actually windward at that time. However, the avalanche potential would certainly increase once the strong northerly winds transported the new snow back over the ridge and onto those south-facing slopes that had a good sliding surface below.

These discussions should start to lead you down the path to better understanding the forecast as well as becoming your own forecaster which is what we truly need if we are to spend time in the backcountry!

Happy Holidays and Be Safe!