National Weather Service Warning - Special Avalanche Bulletin for West Slopes Central Cascades and Passes
Issued: 1:38 PM May 27 Will Expire: 2:00 PM May 28
Summary Avalanche Forecast for Olympics and Washington Cascades
Northwest Weather and Avalanche Center Seattle Washington
1:37 PM PDT Fri May 27 2011
Please note that regularly scheduled mountain weather and avalanche
forecasts for the past winter season have ended. However weather and
snow conditions will continue to be monitored this spring at the
Northwest Weather and Avalanche Center with the information that
remains available. Any statements will be available on the NWAC phone
recordings and on the NWAC Web site. These statements apply to back
country avalanche terrain below 7000 feet and do not apply to operating
ski areas or highways.
Avalanche Forecast
Special Avalanche Conditions Statement for Memorial Day Weekend
Recent: Trip reports mainly on Turns All Year for last Sunday to
Tuesday indicated varied conditions depending on time of day weather
wind and slope aspect. Skier triggered 4-8 inch surface wet snow
avalanches were seen on steep sun exposed slopes. Crusts were also
reported in fairer weather during evening through morning hours. A
climbing ranger reported a cornice collapse triggered a 4-6 foot wind
slab on a north-northeast slope in the White River Canyon on Mt Hood
last weekend. The wet cool weather this spring has caused consolidation
and stabilizing to be perhaps a month behind normal at higher
elevations.
Current: A front crossed the Northwest Wednesday. This was followed by
another weaker front on Thursday. An upper short wave is moving to the
Northwest on Friday. This weather has caused lowering snow levels and
rain or snow depending on elevation. 24 hour precipitation amounts for
Wednesday morning to Friday morning range from about .6-1.2 inches at
NWAC sites along the Cascade crest. Snow levels lowered enough for this
to likely cause 4-10 inches of snowfall above about 5-6000 feet during
that period. And another 2-4 inches seems possible on Friday and Friday
night above about 5000 feet. So there should be up to 6-14 inches of
recent snowfall to possibly contend with near and west of the crest
above 5-6000 feet this coming weekend. This snowfall may have been
heaviest on the volcanoes.
Memorial Day Weekend: A fairly large low pressure system should move
across Oregon and to Nevada on Saturday. This should cause light
showers mainly in the Cascades and possibly on both sides of the crest
with about 4-5000 foot snow levels. A weak ridge is indicated to cross
the Northwest on Sunday with snow levels rising to 6-7000 feet. Models
seem to indicate sufficient moisture for a partly to mostly cloudy
forecast for Sunday and the NWS has a chance of showers. Another low
pressure system is currently indicated to move south over the Northwest
coastal waters on Monday. This should cause an increasing south flow
and the GFS model currently indicates showers by Monday afternoon with
snow levels further rising to about 7-8000 feet.
So pay close attention to snow conditions if you decide to venture to
higher elevations Memorial Day weekend. Potentially dangerous natural
or triggered wet snow avalanches seem possible mainly during the warmer
midday and afternoon hours especially on the volcanoes. Sun effects may
make this mostly likely on slopes facing the sun but beware of
increasing surface wet snow conditions on all steep aspects each day.
Wet snow deeper than a few inches and increasing natural or triggered
snow balling or avalanches are signs of increasing avalanche danger.
Remember that undisturbed snow conditions may be very different a short
distance from packed snow trails at higher elevations. Avoid walking on
cornices and slopes below cornices. Rain wetted surface snow should
also be found at lower elevations. But greater consolidation may make
snow conditions safer at lower elevations. So a trip at lower
elevations may be a better choice if you want to be in the mountains
this Memorial Day weekend.
Please have a safe and enjoyable spring!
Snowpack Synopsis
n/a
Issued: 1:38 PM May 27 Will Expire: 2:00 PM May 28
Summary Avalanche Forecast for Olympics and Washington Cascades
Northwest Weather and Avalanche Center Seattle Washington
1:37 PM PDT Fri May 27 2011
Please note that regularly scheduled mountain weather and avalanche
forecasts for the past winter season have ended. However weather and
snow conditions will continue to be monitored this spring at the
Northwest Weather and Avalanche Center with the information that
remains available. Any statements will be available on the NWAC phone
recordings and on the NWAC Web site. These statements apply to back
country avalanche terrain below 7000 feet and do not apply to operating
ski areas or highways.
Avalanche Forecast
Special Avalanche Conditions Statement for Memorial Day Weekend
Recent: Trip reports mainly on Turns All Year for last Sunday to
Tuesday indicated varied conditions depending on time of day weather
wind and slope aspect. Skier triggered 4-8 inch surface wet snow
avalanches were seen on steep sun exposed slopes. Crusts were also
reported in fairer weather during evening through morning hours. A
climbing ranger reported a cornice collapse triggered a 4-6 foot wind
slab on a north-northeast slope in the White River Canyon on Mt Hood
last weekend. The wet cool weather this spring has caused consolidation
and stabilizing to be perhaps a month behind normal at higher
elevations.
Current: A front crossed the Northwest Wednesday. This was followed by
another weaker front on Thursday. An upper short wave is moving to the
Northwest on Friday. This weather has caused lowering snow levels and
rain or snow depending on elevation. 24 hour precipitation amounts for
Wednesday morning to Friday morning range from about .6-1.2 inches at
NWAC sites along the Cascade crest. Snow levels lowered enough for this
to likely cause 4-10 inches of snowfall above about 5-6000 feet during
that period. And another 2-4 inches seems possible on Friday and Friday
night above about 5000 feet. So there should be up to 6-14 inches of
recent snowfall to possibly contend with near and west of the crest
above 5-6000 feet this coming weekend. This snowfall may have been
heaviest on the volcanoes.
Memorial Day Weekend: A fairly large low pressure system should move
across Oregon and to Nevada on Saturday. This should cause light
showers mainly in the Cascades and possibly on both sides of the crest
with about 4-5000 foot snow levels. A weak ridge is indicated to cross
the Northwest on Sunday with snow levels rising to 6-7000 feet. Models
seem to indicate sufficient moisture for a partly to mostly cloudy
forecast for Sunday and the NWS has a chance of showers. Another low
pressure system is currently indicated to move south over the Northwest
coastal waters on Monday. This should cause an increasing south flow
and the GFS model currently indicates showers by Monday afternoon with
snow levels further rising to about 7-8000 feet.
So pay close attention to snow conditions if you decide to venture to
higher elevations Memorial Day weekend. Potentially dangerous natural
or triggered wet snow avalanches seem possible mainly during the warmer
midday and afternoon hours especially on the volcanoes. Sun effects may
make this mostly likely on slopes facing the sun but beware of
increasing surface wet snow conditions on all steep aspects each day.
Wet snow deeper than a few inches and increasing natural or triggered
snow balling or avalanches are signs of increasing avalanche danger.
Remember that undisturbed snow conditions may be very different a short
distance from packed snow trails at higher elevations. Avoid walking on
cornices and slopes below cornices. Rain wetted surface snow should
also be found at lower elevations. But greater consolidation may make
snow conditions safer at lower elevations. So a trip at lower
elevations may be a better choice if you want to be in the mountains
this Memorial Day weekend.
Please have a safe and enjoyable spring!
Snowpack Synopsis
n/a
