MOUNTAIN WEATHER FORECAST FOR THE OLYMPICS WASHINGTON CASCADES 
AND MT HOOD AREA
NORTHWEST WEATHER AND AVALANCHE CENTER SEATTLE WASHINGTON
130 PM PST TUE FEB 10 2009

NWAC Program administered by:
USDA-Forest Service
with cooperative funding and support from:
Washington State Department of Transportation
National Weather Service
National Park Service
Washington State Parks and Recreation Commission
Pacific Northwest Ski Area Association
Friends of the Avalanche Center
and other private organizations.

This forecast is prepared primarily for federal, state and 
private snow safety programs in Washington and Northern 
Oregon.

WAZ513-518-519-019-042-501-502-ORZ011-111700-

&&

WEATHER SYNOPSIS FOR TUESDAY AND WEDNESDAY
A northwest flow over the northeast Pacific Ocean should 
maintain a storm track that mostly misses the Northwest the 
next few days. A series of low pressure system should move 
southeast over the Northwest coastal waters to the Oregon 
California border area.

The first weakening low is about 450 miles off the 
Washington coast Tuesday early afternoon and moving 
southeast along the storm track. A front is clearly seen on 
satellite images moving out of the low. The front should 
cross the Olympics about Tuesday midday and the Cascades 
Tuesday afternoon. Crest level winds and precipitation 
should be strongest over the Olympics and the volcanoes in 
the south Cascades. Surface pressure gradients should remain 
easterly over the Cascades and this should help limit snow 
in the Cascade passes. A little more than usual snow may 
reach the Cascade east slopes due to the southerly crest 
level flow along the front.

The further weakening low should move to the Oregon 
California border area on Wednesday morning. This should 
help crest level winds to decrease and light showers to end 
Wednesday morning. A weak shortwave ridge in the northwest 
flow and weak surface high pressure should move to the 
Northwest Wednesday afternoon and evening. This should cause 
further decreasing crest level winds and partly to mostly 
cloudy sky conditions.
&&

WEATHER FORECAST FOR TUESDAY AND WEDNESDAY

*	OLYMPICS-
Tuesday afternoon and evening: Increasing light to 
moderate snow.
Tuesday night: Decreasing light snow showers.
Wednesday morning: Light snow showers ending.
Wednesday afternoon and night: Partly or mostly cloudy.

*	WASHINGTON CASCADES NEAR AND WEST OF THE CREST- 
*	CASCADE PASSES INCLUDING STEVENS, SNOQUALMIE AND WHITE 
PASSES-
Tuesday afternoon and evening: Increasing light to 
occasional moderate snow heaviest on the volcanoes of the 
central to south Cascades.
Tuesday night: Decreasing light snow showers.
Wednesday morning: Light snow showers ending.
Wednesday afternoon and night: Partly or mostly cloudy.

*	EAST SLOPES WASHINGTON CASCADES-
Tuesday afternoon and evening: Increasing light to 
occasional moderate snow heaviest south part.
Tuesday night: Decreasing light snow showers.
Wednesday morning: Light snow showers ending.
Wednesday afternoon and night: Partly or mostly cloudy.

*	MT HOOD AREA-
Tuesday afternoon and evening: Increasing light to 
moderate snow.
Tuesday night: Decreasing light snow showers.
Wednesday morning: Light snow showers ending.
Wednesday afternoon and night: Partly or mostly cloudy.
&&

SNOW LEVELS-CASCADE MTNS
Near sea level N to S Tue morn
1000 ft N to C, 2000 ft S Tue aft and eve
Near sea level N to C, 1000 ft S Wed morn
FREEZING LEVELS
2000 ft N, 3000 ft S Wed aft
Lowering Wed night
Near sea level N to C, 1000 ft S Thu morn

SNOW LEVEL-OLYMPIC MTNS
Near sea level N to S Tue morn
1000 ft Tue aft to Wed morn
FREEZING LEVELS
3000 ft Wed aft
Lowering Wed night
1000 ft Thu morn

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
                    	WED 	    THU

*	HURRICANE RIDGE	.25	     0

*	MT BAKER       	LT .25	     0
*	WASHINGTON PASS	LT .25	     0
*	STEVENS PASS   	LT .25	     0
*	SNOQUALMIE PASS	LT .25	     0
*	MISSION RIDGE  	LT .25	     0
*	CRYSTAL MTN    	.25	     0
*	PARADISE       	.25-.5	     LT .10
*	WHITE PASS     	LT .25	     LT .10
*	MT HOOD        	.25-.5	     LT .25

&&

WINDS IN MILES PER HOUR (MPH)

*	CASCADE PASS LEVEL WINDS
W 5-10 Tue early morn
E 5-10 Tue late morn
E 10-15 Tue aft through Wed morn
E 5-10 Wed aft and eve

*	FREE WINDS AT 5000 FT
SW 15-25 Olympics, SW 10-20 Cascades Tue early morn
SSE 30-40 Olympics, SSE 15-25 Cascades Tue late morn
SW 25-35 Olympics, SSE 15-25 north Cascades, SSE 25-35 
south Cascades Tue aft
SW 10-20 Olympics, SSE 10-20 north Cascades, SW 15-25 
South Cascades Tue eve
SSE 5-10 Olympics and north Cascades, SW 10-20 south 
Cascades Wed morn
W 5-10 Olympics and north Cascades, SE 5-15 south 
Cascades Wed aft and eve

*	FREE WINDS AT 9000 FT
SW 15-25 Tue early morn
SW 40-50 Olympics, SW 15-25 Cascades Tue late morn
SW 25-35 Olympics, SW 20-30 north Cascades, SW 40-50 
south Cascades Tue aft
SW 15-25 Olympics and north Cascades, SW 25-35 South 
Cascades Tue eve
SW 10-20 strongest south Cascades Wed morn
NW 5-15 Olympics and north Cascades, SE 5-15 south 
Cascades Wed aft and eve
&&

EXTENDED WEATHER SYNOPSIS FOR THURSDAY THROUGH SATURDAY
Another similar but weaker low pressure system should follow 
the storm track southeast over the Northwest coastal waters 
on Thursday and Friday. This weaker system should cause less 
of an increase in crest level winds and precipitation. 
Surface pressure gradients should remain easterly and 
continue to help limit precipitation.

Yet another weak low pressure system low should follow the 
storm track over the coastal waters on Saturday and Sunday. 
This system is indicated by the US GFS model to be further 
offshore and to have even less effect on weather in the 
Olympics and Cascades. 

EXTENDED FORECAST FOR THURSDAY THROUGH SATURDAY
Thursday and Thursday night: Increasing clouds Olympics and 
north Cascades and increasing light snow south Cascades.
Friday: Decreasing clouds Olympics and north Cascades and 
light snow showers ending south Cascades.
Saturday: Occasional light snow showers most areas.
 
*	SNOW LEVELS
Near sea level-2000 ft N, 1-2000 ft S Thu to Sat highest 
afternoon hours.

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.

Ferber/Northwest Weather and Avalanche Center

$$