Stampede Pass, Washington

... Winter Weather Advisory now in effect until 10 am PST this
morning...

The Winter Weather Advisory is now in effect until 10 am PST this
morning.

Light freezing rain... snow and sleet will continue into the
morning hours... before turning to scattered showers by this
afternoon. Expect the greatest coverage of precipitation near the
Cascade crest... including the Easton area.

A Winter Weather Advisory is issued when periods of snow...
sleet... or freezing rain will cause travel difficulties. Be
prepared for slippery roads and limited visibilities... and use
caution while driving. For additional weather information... check
our web site at www.Weather.Gov/Pendleton.

&&

Weather synopsis for Monday and Tuesday
as the recent strong split flow over much of The Rockies and
Midwest US moved eastward Monday morning, this allowed upper
level ridging currently along the coast to move eastward
ahead of a consolidating westerly flow around several deep
upper lows that span much of the Gulf of Alaska. The first
upper low lying several hundred miles south-southeast of
Anchorage, AK, around noon has spawned an associated strong
occluded front that covers southern Alaska and most of
north-central BC into Alberta with a trailing cold front
extending west southwestward from northern Vancouver Island
offshore over 1000 miles to a secondary deep upper low south
of the Aleutians. Meanwhile, forecast models and satellite
imagery indicate an associated strong warm front lies draped
over western Washington early Monday afternoon. As the New
Year continues to unfold, increasingly strong west to
southwesterly flow around this upper low complex should
produce increasingly wet weather across much of the region.
While heaviest precipitation with the warm front is expected
across southern BC, increasing light to moderate rain or
snow spread over the Olympics and north-central Washington
Cascades during the morning along with gradually rising
freezing levels and increasing winds. While some warm
frontal moisture should also spread slowly southward mid-day
through Monday afternoon, the main thrust of the warm front
should be remain over the Olympics and north Cascades with
light to moderate rain or snow in the central Cascades, and
only occasional light rain or snow reaching the southern
Washington Cascades and Mt Hood area later Monday afternoon.
With substantial warming aloft and a relatively shallow but
cool easterly surface flow across the Cascade passes, this
should also produce an increasing chance of intermittent
local freezing rain near the Cascade passes Monday afternoon
and evening before the warm front lifts northward.

After the warm front lifts briefly northward later Monday
night, a stronger wave developing along the back edge of the
cold front to the northwest should approach the region
Tuesday morning. While this should produce slightly and
briefly decreasing showers in the south and decreasing light
precipitation in the central Cascades late Monday night and
early Tuesday, this break should be followed by
increasingly heavy rain or snow, strengthening winds and
further brief warming in the Olympics and north-central
Cascades Tuesday morning. As the front moves southeastward
over the region mid-day and Tuesday afternoon, increasing
rain or snow should spread further southward along with
continued strong winds and slow cooling. This should result
in a continuing chance of local freezing rain near the
Cascade passes and Cascade east slopes until a pass wind
shift expected early-mid Tuesday afternoon in the central
Washington Cascades. Following this wind shift, the main
jetstream should shift southward over Oregon and rain or
snow should generally decrease and become more showery over
much of the area, with moderate showers expected to slowly
decrease Tuesday night along with further cooling and
diminishing winds. However, the decrease in precipitation
should be very brief, especially in the south, as another
moderate to strong disturbance in the strong westerly flow
to the south is expected to slowly lift further moisture
northward over the area on Wednesday.

&&

Weather forecast for Monday and Tuesday

*olympics-
moderate to occasionally heavy rain or snow Monday
afternoon and night, heaviest west and southwest slopes.
Moderate to heavy rain or snow increasing Tuesday
morning. Heavy rain or snow decreasing and becoming more
showery Tuesday afternoon. Moderate showers Tuesday
night.

*Washington Cascades near and west of the crest from
Snoqualmie Pass northward-
moderate to occasionally heavy rain or snow north and
moderate rain or snow south Monday afternoon. Moderate
rain or snow continuing north but briefly decreasing in
the south part Monday night. Rain or snow increasing
Tuesday morning and becoming heavy later Tuesday morning
and mid-day. Rain or snow decreasing early-mid Tuesday
afternoon and becoming showery. Moderate showers Tuesday
night.

*Washington Cascades near and west of the crest south of
Snoqualmie Pass -
occasional light rain or snow north and light showers
south Monday afternoon, decreasing Monday night and early
Tuesday. Increasing light to moderate rain or snow
spreading southward Tuesday morning. Moderate to heavy
rain or snow later Tuesday morning and Tuesday afternoon,
decreasing and becoming more showery later Tuesday
afternoon or evening. Moderate showers Tuesday night.

*Cascade passes from Snoqualmie Pass northward, including
Stevens, Snoqualmie passes -
moderate to occasionally heavy snow north and moderate
rain or snow south Monday afternoon and evening with
periods of freezing rain. Moderate snow or freezing rain
decreasing later Monday night south but increasing again
Tuesday morning and becoming heavy later Tuesday morning
and mid-day. Precipitation decreasing and becoming mostly
rain or snow early-mid Tuesday afternoon north and
central and later Tuesday afternoon south. Moderate
showers later Tuesday afternoon and night.

*Cascade passes south of Snoqualmie Pass, including White
Pass-
occasional light snow north and light showers south
Monday afternoon with chance local freezing rain. Light
snow, rain or local freezing rain decreasing Monday night
and early Tuesday. Increasing light to moderate snow or
freezing rain spreading southward Tuesday morning.
Moderate to heavy rain, snow or local freezing rain later
Tuesday morning and early-mid Tuesday afternoon,
decreasing and becoming mostly rain or snow later Tuesday
afternoon and evening. Moderate snow showers Tuesday
night.

*East slopes Washington Cascades-
cloudy north and partly cloudy south early Monday
morning. Clouds increasing later Monday morning and
afternoon with light to moderate snow developing north,
increasing light snow central and light showers south,
with increasing chance local freezing rain. Clouds and
light precipitation decreasing south and central
overnight, but light to moderate snow, rain or local
freezing rain continuing north, mainly higher terrain
near the crest. Light to moderate snow, rain or local
freezing rain spreading southward and increasing later
Tuesday morning and early Tuesday afternoon, decreasing
late Tuesday afternoon and becoming more showery. Light
to moderate showers Tuesday night.

*Mt Hood area-
cloudy with light showers or occasional light rain or
snow Monday afternoon. Clouds and showers decreasing
Monday night and early Tuesday. Increasing clouds with
increasing light to moderate rain or snow redeveloping
midday. Moderate to heavy rain or snow Tuesday afternoon,
decreasing Tuesday evening. Moderate showers Tuesday
night increasing early Wednesday and becoming moderate
rain or snow.
&&

Snow levels-Cascade mtns
4500 ft N, 5500 ft c, 6500 ft S early Monday afternoon
5000 ft N, 6500 ft c, 7000 ft S mid-late Monday afternoon
6000 ft N, 7000 ft c, 8500 ft S Monday night
6000 ft N, 7000 ft c, 8000 ft S Tuesday morning
5000 ft N, 6000 ft c, 8000 ft S mid-day
4500 ft N, 5000 ft c, 6000 ft S Tuesday afternoon
3000 ft N and c, 4500 ft S Tuesday night, except snow
levels locally near the surface in a shallow easterly
flow through Tuesday morning, rising to near free air
levels early-mid Tuesday afternoon

Snow levels-olympic mtns
6500 ft Monday afternoon
7500 ft Monday night
7000 ft Tuesday morning
6000 ft mid-day
4000 ft Tuesday afternoon
3000 ft Tuesday night

Cascade snow/freezing levels refer to the northern Washington Cascades
(n) through Mt Hood area (s). Central Washington Cascade snow levels
(typically near Snoqualmie pass) are normally midway between indicated N
and S levels. Note that surface snow/freezing levels are common near
the passes during easterly pass flow and may result in multiple
snow/freezing levels.

&&

24 hour forecast of precipitation in inches of water
equivalent ending at 4am
                    Tue Wed

*hurricane ridge.5-.75 .75-1

*mt Baker 1-1.5 1.5-2
*washington pass.5 .5-.75
*stevens pass .5 1
*snoqualmie pass.5-.75 1
*mission ridge lt .25 .25
*crystal mtn .25 .75-1
*paradise .25-.5 1-1.5
*white pass lt .25 .5-.75
*mt Hood lt .25 1-1.5

&&

Winds in miles per hour (mph)

*cascade pass level winds
E 5-15 Monday afternoon and night
E 5-10 Tuesday morning
W 10-20 with higher gusts Tuesday afternoon and evening
W 10-15 Tuesday night, decreasing late

*free winds at 5000 ft
W-SW 20-40 Cascades, 30-45 Olympics Monday afternoon
W-SW 20-40 Cascades, 30-50 Olympics Monday night
W-SW 25-40 Cascades, 30-50 Olympics early Tuesday morning
S-SW 25-40 Cascades, 40-60 Olympics late Tuesday morning
W-SW 30-50 Cascades, W 30-50 Olympics Tuesday afternoon
W-SW 15-30 Tuesday night

*free winds at 9000 ft
W-SW 40-60 N, 30-45 c, 20-40 S Monday afternoon
W-SW 40-60 N, 30-50 c, 25-40 S Monday night
W-SW 50-70 N, 40-60 c, 30-50 S Tuesday morning
SW 50-70 N, 40-60 S mid-day
W-SW 50-70 Tuesday afternoon
W 30-50 Tuesday night, decreasing late

&&

Extended weather synopsis for Wednesday through Friday
a moderate to strong upper short wave in the strong westerly
flow over Oregon is expected to lift a moderate frontal
system very slowly northward over Oregon and southern
Washington on Wednesday, with heaviest precipitation
expected near Mt Hood and extreme southern Washington. The
associated south to southeasterly upper flow with this
disturbance should also help focus some of the precipitation
along the east slopes of the southern Cascades, some
increase in light to moderate rain or snow should reach most
areas in north-central Washington Wednesday afternoon as the
northern part of the following upper trough moves over the
area. Following this surface and upper low passage across
northern Oregon late Wednesday and early Thursday, a
moderate but cool west to northwesterly flow should produce
moderate to occasionally heavy snow showers Thursday morning
and early afternoon before slowly dying out late Thursday
into early Friday as weak surface and upper ridging move
onshore.

However, the stormy New Year is expected to resume again by
mid-day Friday as an increasingly strong westerly flow is
expected to carry another vigorous disturbance over the
region later Friday morning into Friday evening. This should
bring heavy rain or snow, strong winds and relatively brief
and slight warming. Several following short wave troughs
expected to follow the front should combine with abundant
showers to produce heavy snow or snow showers from Friday
night through much of Saturday, with some locally heavy
snowfall likely.

Extended forecast for Wednesday through Friday
increasing light to moderate rain or snow spreading slowly
northward Wednesday, heaviest in the south and along the
east slopes of the southern Washington Cascades. Windy in
the south and Mt Hood area with brief warming, mainly south.
Moderate to occasionally heavy showers and cooler late
Wednesday through Thursday morning. Moderate showers
Thursday afternoon decreasing late with some partial
clearing overnight. Moderate rain or snow increasing later
Friday morning becoming moderate to heavy Friday afternoon
and evening. Moderate to heavy showers Friday night
continuing early-mid Saturday.

*Snow levels
2-4000 ft N, 3-5000 ft S early Wednesday
2-4000 ft N, 3-5000 ft c, 4-6000 ft S mid-late Wednesday
1-3000 ft N, 2-4000 ft S Wednesday night
1-3000 ft N and S early Thursday
sea level to 1000 ft N, 500-1500 ft S mid-late Thursday
through early Friday
1-3000 ft N, 2-4000 ft S late Friday, except snow levels
lowering to near the surface Cascade passes and east
slopes Wednesday, rising to near free air levels late
Wednesday

Nwac weather data and forecasts are also available by calling
206-526-6677 for Washington, 503-808-2400 for the Mt Hood
area, or by visiting our web site at www.Nwac.US. Also note
that field snowpack information is often available on the foac
website at www.Avalanchenw.Org, and weather and avalanche
glossaries for commonly used terms in the forecasts can be
found on the nwac education Page.

Moore/northwest weather and avalanche center