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 with your avalanche and mountain weather
advisory. Today is Saturday, February
19th, 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:
When the winds picked up yesterday, they started moving snow and
have not stopped. All of the terrain
above tree line and the open, unsheltered slopes below tree line will be wind
affected in some way. The trees still
hold the best powder. Two crusts still
exist: a rain crust that is buried under about 3-5 inches of snow and a sun
crust on the open southerly slopes that formed on Thursday. As it continues to snow today, visibility
will be poor and stability will decrease, so be careful.
The road to the Geyser Pass Trailhead is in good shape. The new snow could make it a bit more
treacherous as the day wears on. 4WD is
recommended and chains might help as well.
Current Conditions: (click location for latest data)
Geyser
Pass Trailhead (9,600): 44 at the
SNOTEL, 51 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:
Around 80 to 85 of settled snow on the ground.
Mountain Weather: (At 10,500)
Winter storm warning in effect until 6 am mst Sunday.
There is a large low-pressure system over California that will continue to push
waves of moisture and energy our way.
Likely we will experience periodic episodes of heavy snowfall in the
mountains through the weekend. The
total accumulation that we could get out of this storm is between 8 and 14
inches. Our winds will continue to be
out of the SW.
Saturday. Snow showers with accumulation of 3 to 5 inches. Southwest winds 15 to
25 mph. Highs in the 30s.
Saturday night. Snow will
continue through the night with accumulation of 3 to 5 inches. Southwest winds 10 to 20 mph. Lows in the 20s.
Sunday. More snow showers bringing another 2 to 4 inches and more
southwest winds at 10 to 15 mph. Highs
in the 30s.
Avalanche Conditions:
As
this storm rolls in, the winds have increased and have been transporting snow all
day yesterday, through the night, and will continue to do so today. Watch out for those leeward, wind-loaded
slopes. On a cross-loaded test slope
yesterday, I was able to trigger a very small slide by simply stepping on the
slope! We still have those three
persistent weak layers lurking in the upper part of our snow pack (where our
force as skiers and riders can be easily transmitted): the rain crust with the
new snow on top of it, the dense heavy layer sitting on a light and fluffy
layer, and a buried surface hoar layer!!!
All three of these layers failed easily yesterday as I performed bonding
tests on them. With more loading both
by snow accumulation and wind-loading, we can expect smaller and smaller
triggers to cause failure in these layers, and we can expect those failures to
propagate into full blown people-burying slides! I am still seeing shooting cracks, feeling collapses under my
skis, and hearing whumphing noises. I
think times like these are some of the trickiest times to be a backcountry
user. Mother nature is not giving us
the huge obvious signs of natural slides releasing, but the snow pack is weak
likely to fail with only a small amount of added stress (i.e. you). Be observant and alert! Look for those less obvious signs of instability
(cracking under your skis, whumphing, collapsing, cracks in the slope, etc.)
and pay attention to them.
The
most precarious slopes that I found were on steeper North thru East
aspects. They are wind-loaded and
preserve instabilities quite well. 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 snow
pack hangs in a delicate balance right now; all it is looking for is some added
stress (a.k.a. you or the new snow that we are going to get!) to set it
loose.
The Bottom Line for today:
An avalanche danger of CONSIDERABLE
on slopes greater than 35 degrees on all N-E aspects at all elevations. For the
rest of the La Sals, I am going to rate the avalanche danger at MODERATE.
Remember that CONSIDERABLE
means that human triggered slides are probable. Keep in mind: as we get more snow this danger will
INCREASE!
Nordic and Skate Skiing:
There
are Nordic tracks set to Geyser Pass and into Gold Basin; however as this storm
rolls through they will soon disappear.