Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Friday - December 16, 2016 - 6:42am
bottom line

I have issued an Avalanche Warning for the La Sal and Abajo Mountains. Strong winds and heavy snow have created a HIGH avalanche danger in upper elevation terrain, and human triggered and natural avalanche activity are likely in these areas. At mid elevations the avalanche danger is CONSIDERABLE. Backcountry travelers today need to have excellent route finding and terrain selection skills. Stay off of and out from under steep avalanche prone terrain.




avalanche warning

THE FOREST SERVICE UTAH AVALANCHE CENTER IN MOAB UTAH HAS ISSUED A BACKCOUNTRY AVALANCHE WARNING.

* TIMING…IN EFFECT FROM 6 AM MST FRIDAY MORNING TO 6 AM MST SATURDAY

* AFFECTED AREA…MOUNTAINS OF SOUTHEASTERN UTAH INCLUDING THE LA SAL AND ABAJO MOUNTAINS

* AVALANCHE DANGER…THE AVALANCHE DANGER FOR THE WARNING AREA IS EXPECTED TO BE HIGH OVER THE NEXT 24 HOURS

* IMPACTS…POTENTIAL HEAVY SNOW COMBINED WITH WIND WILL LIKELY CREATE WIDESPREAD AREAS OF UNSTABLE SNOW. BOTH HUMAN TRIGGERED AND NATURAL AVALANCHES ARE LIKELY. STAY OFF OF AND OUT FROM UNDER SLOPES STEEPER THAN 30 DEGREES

special announcement

The timing with this storm is not coinciding well with the plow schedule and you may be on your own in accessing the Geyser Pass Trailhead this weekend. The rain/snow line is above the Loop Road however, and most of the snow accumulation is above the parking lot. I'll be up today, and will provide a full report for access tomorrow.

current conditions

A warm and windy storm has has delivered 8" of dense, heavy snow since 2:00 p.m. yesterday afternoon at the Gold Basin study plot and 5" at the Geyser Pass Trailhead. More snow and wind is on tap through tomorrow morning with a foot or more of new snow in the forecast. Overnight winds have been serious, averaging 30-40 mph from the SSW with gusts into the 50's. It's a warm 33 degrees at the Geyser Pass Trailhead and 24 on Pre Laurel Peak.

Storm totals and temperature in Gold Basin.(10,000')

Wind, temperature and humidity on Pre Laurel Peak.(11,700')

Snow totals, temperature and snow/water equivalent at the Geyser Pass Trailhead.(9600')

Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Strong gusty winds, and dense heavy snow make the perfect combination for dangerous wind slab formation. Recognizable by their smooth, rounded, appearance, areas of drifted snow should be avoided on slopes steeper than 30 degrees. The danger will be highest on slopes facing the north half of the compass but in wind exposed terrain they may be present on all aspects.

Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

I've been monitoring weak layers in our snowpack during the dry spell and we have developed faceted, sugary snow near the old snow surface, mid-way down in the pack, and at ground level. The additional load of snow may be enough to tip the balance and cause an avalanche to release on one of these buried weak layers. You are most likely to encounter this problem on steep, rocky terrain facing the north half of the compass, but there are areas where it may wrap around into southeasterly facing terrain at upper elevations.

weather

A large winter storm and strong cold front will move through the area later today and tonight. Ahead of the front, southwest flow will pick up keeping warm, above normal temperatures in the forecast for this afternoon. Widespread precipitation will occur with snow above 8,000 feet for the mountains and rainfall below thanks to these warm temperatures. These mild temperatures are playing games with the rain/snow line and are making for a very tricky and complicated forecast for elevations near and below 8000 feet. Some gusty winds and maybe even a few rumbles of thunder will also be possible this afternoon ahead of the front. Most of the precipitation is expected to end around midday Saturday. Snowfall amounts for the mountains will fall in the 1 to 2 foot range with some higher amounts possible. Valleys may see some snowfall as well after the front passes through with a few inches possible on Saturday.

Today

Snow. High near 30. Very windy, with a west southwest wind 30 to 40 mph, with gusts as high as 55 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 7 to 11 inches possible.

Tonight

Snow. Low around 2. Wind chill values as low as -10. Windy, with a west northwest wind 25 to 30 mph decreasing to 15 to 20 mph after midnight. Winds could gust as high as 45 mph. Chance of precipitation is 90%. New snow accumulation of 5 to 9 inches possible.

Saturday

Snow likely, mainly before 11am. Partly sunny and cold, with a high near 10. Wind chill values as low as -20. Blustery, with a northwest wind 15 to 20 mph. Chance of precipitation is 60%. New snow accumulation of 2 to 4 inches possible.

Saturday Night

Partly cloudy, with a low around -1. Wind chill values as low as -10. West northwest wind 5 to 15 mph.

Sunday

Sunny, with a high near 11. Northwest wind 10 to 15 mph.