Manti-La
Sal Avalanche Center
US Forest Service Manti-La Sal National
Forest
Introduction: Good
morning! This is Max Forgensi with the
USFS Manti-La Sal Avalanche Center.
This is your avalanche and mountain weather advisory. Today is Sunday, February 20th,
2005 at 7:30 am. This bulletin is
sponsored in part by Western Spirit,
offering cycling adventures in Moab and beyond, proud sponsors of the Friends
of the Manti-La Sal Avalanche Center.
This advisory will expire in 24 hours.
To see past advisories check out the ARCHIVE. To see current conditions go to our WEATHER PAGE. To see photos go to the AVIPHOTOS page.
General Conditions:
The storm materialized yesterday, and we got 6 of snow during the
day and at least 2 more last night.
The wind continued to blow all day and through the night from the SW at
15-25 mph with gusts above tree line at 35-40 mph. It has really loaded those North through East aspects! All of the terrain above tree line and the
open, unsheltered slopes below tree line will be wind affected in some
way. The wind even managed to influence
the snow in the trees in some areas.
Skiing in the trees away from their borders with open areas was
fantastic yesterday. The mountains are
still in the clouds so visibility will be an issue; remember to watch out for
signs that you are in a slide path even if you cant see above you (unexplained
open areas, no branches on the uphill side of trees, etc.).
The road to the Geyser Pass Trailhead has not been plowed yet this
morning and had 10+ inches of snow on it yesterday afternoon due to
drifting. 4WD is recommended and chains
might help as well.
Current Conditions: (click location for latest data)
Geyser
Pass Trailhead (9,600): 48 at the
SNOTEL, 55 at the stake, it is 28 degrees at the TH at 6:00 am.
Pre-Laurel
Peak (11,700): AARRGGHH! Back to
the drawing board on this one, hopefully by Monday evening well have
read-outs.
Gold Basin and South Mountain:
80 of settled snow on the ground.
Mountain Weather: (At 10,500)
Winter storm warning in effect until 6 pm MST Sunday.
Today we have another unstable moisture-rich air mass moving across the area;
it has the potential to create a convective storm, which usually means high
snowfall rates (2-3/hr) and maybe some thunderstorms. Expect to see episodes of heavy snowfall
throughout the day. The storm will lose
energy and begin to stabilize tonight, and we should see a lull before more
storms roll through the area next week.
Sunday: Snow
showers and isolated thunderstorms. Snow accumulation 2 to 4 inches. Highs 35
to 45. Southwest winds 10 to 20 mph.
Sunday night: Mostly cloudy with a chance of snow
showers in the evening. Then partly cloudy with a slight chance of snow after
midnight. Lows in the 20s. Southwest winds 10 to 15 mph and gusty, decreasing
to southwest 10 to 15 mph after midnight. Chance of snow 50 percent.
Monday: Mostly cloudy with a 40 percent
chance of snow. Highs 35 to 45. Southwest winds 10 to 15 mph.
Avalanche Conditions:
We are looking at some rapid snowfall and lots of
wind loading! We got 6 of snow in less
than 3 hours yesterday, and we are expecting the even greater snowfall rates
for today. The wind has also been
howling throughout this storm. It has
been moving snow since Friday and has really loaded those North through East
aspects. With such strong winds for
this amount of time, we are also seeing some wind loading into the trees and
further down from the ridgelines. On my
leeward and cross-loaded tests slopes yesterday, I saw very stiff 6-12 wind
slabs break loose and often step down 18-24 to the older weak layers, and
this was before it started snowing. The
wind slabs will be even larger today.
These wind slabs are tricky because they feel supportive and stiff until
it is too late, and they break very quickly and cleanly as a slab. Their stiffness allows cracks to propagate
farther across the snow pack.
Triggering slides remotely becomes much more of an issue in slabs like
these. I watched cornices fail at least
3 feet back from the ridgeline, so be aware of where you are standing. We have lots of wind loading, 8 of new snow
with more on the way that is supposed to accumulate very fast, and weak layers
in the snow pack. Hmm, sounds like
great conditions for avalanches! I
would expect to see some natural slides today that start with a failure in the
wind slabs and step down to our underlying weak layers. Even where the slopes may not be wind loaded
we have still added weight to an already weak snow pack, so it is that much
closer to failure. Our added weight as
a skier or rider could easily tip scales and cause a slope to fail. Be observant and alert! Look for those signs of instability
(avalanche activity, cracking under your skis, whumphing, collapsing, cracks in
the slope, etc.) and weather red flags (rapid accumulation, wind loading, etc.). When you see them, pay attention.
I would try to ski lower angled, sheltered, treed
slopes and ridgelines today. Those
North thru East aspects that are wind loaded are going to be scary! Be aware of trigger points (places where we
are more likely to cause failures in the weak layers) like steep convex
rollovers, shallow rock outcroppings (where a skiers weight can transfer energy
deeper into the snow pack), trees, and tender cornices on any slope.
The Bottom Line for today:
An avalanche danger of CONSIDERABLE
with pockets of HIGH in the wind loaded
areas (especially those North through East aspects) on slopes greater than 30
degrees on all aspects at all elevations.
Nordic and Skate Skiing:
Nordic
skiing will be a great strength-building workout today.