MOUNTAIN WEATHER FORECAST FOR THE OLYMPICS WASHINGTON CASCADES 
AND MT HOOD AREA
NORTHWEST WEATHER AND AVALANCHE CENTER SEATTLE WASHINGTON
130 PM PST MON FEB 16 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-ORZ011-171700-

&&

WEATHER SYNOPSIS FOR MONDAY AND TUESDAY
A few days ago the pattern had weak low pressure systems 
moving southeast over the Northwest coastal waters. Now the 
pattern has become more split and the lows are larger, slower 
moving, further offshore and tending to move to California. 
The current large slow moving low pressure system began to 
move across California on Sunday with a couple of weak 
circulation centers within the low. A band of moisture moved 
north out of the low on Sunday and caused light amounts of 
snow at Mt Hood and in the Olympics and Washington Cascades on 
both sides of the crest. The remnant of this band is 
dissipating over the north Cascades on Monday morning.

The low should continue to move slowly across California on 
Monday and Tuesday. A very weak trough over the International 
border Monday should drift west and mostly dissipate Tuesday. 
This should cause very weak flow aloft and little change in 
the air mass over the Northwest. Satellite images Monday 
afternoon indicate a lot of clouds east of the crest and less 
to the west. A weaker band of moisture is indicated to move 
north out of the low and affect the Mt Hood area Monday 
afternoon and Tuesday with little effect further north. All in 
all this should cause generally uneventful but cool weather in 
the Olympics and Cascades Monday and Tuesday. Weak offshore 
surface pressure gradients may areas of low clouds to linger 
east of the Cascade crest.
&&

WEATHER FORECAST FOR MONDAY AND TUESDAY

*	OLYMPICS-
Monday afternoon through Tuesday morning: Partly or 
mostly cloudy with slight chance of light snow showers.
Tuesday afternoon and night: Partly cloudy.

*	WASHINGTON CASCADES NEAR AND WEST OF THE CREST-
*	STEVENS, SNOQUALMIE AND WHITE PASSES-
Monday afternoon through Tuesday morning: Partly or 
mostly cloudy with slight chance of light snow showers.
Tuesday afternoon and night: Partly cloudy.

*	EAST SLOPES WASHINGTON CASCADES-
Monday afternoon through Tuesday morning: Cloudy with 
chance of light snow showers.
Tuesday afternoon and night: Partly or mostly cloudy.

*	MT HOOD AREA-
Monday afternoon through Tuesday morning: Cloudy with 
chance of light snow showers.
Tuesday afternoon and night: Partly or mostly cloudy.
&&

SNOW LEVELS-CASCADE MTNS
2000 ft N, 3000 ft S Mon morn through Tue night except 
near the surface night and morning hours especially 
passes and east slopes and slightly higher afternoon 
hours.

SNOW LEVELS-OLYMPIC MTNS
2500 ft Mon morn through Tue night
Near sea level Tue morn except near the surface night and 
morning hours and slightly higher afternoon hours.

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
                    	MON 	    TUE

*	HURRICANE RIDGE	LT .10	     LT .10

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

&&

WINDS IN MILES PER HOUR (MPH)

*	CASCADE PASS LEVEL WINDS
E 5-15 Mon aft
E 5-10 Mon eve
E 0-10 Tue morn
Light variable Tue aft and eve

*	FREE WINDS AT 5000 FT
SE 5-10 Mon aft to Mon eve
Light variable Tue morn
SW 5-15 Tue aft and eve

*	FREE WINDS AT 9000 FT
S-SW 10-15 Mon aft to Mon eve
SW 0-10 Tue morn
SW 1-0-20 Tue aft and eve
&&

EXTENDED WEATHER SYNOPSIS FOR WEDNESDAY THROUGH FRIDAY
The next large slow moving cut off low pressure system is 
indicated by the US GFS model to linger further west of 
California near 140 degrees west the latter half of the 
week. This is indicated to help an upper ridge and weak 
surface high pressure to build over the Northwest and west 
US. This should cause light crest level winds and decreasing 
cloud cover over the Olympics and Cascades.

EXTENDED FORECAST FOR WEDNESDAY THROUGH FRIDAY
Wednesday and Wednesday night: Partly cloudy.
Thursday through Friday: Partly sunny days and partly clear 
nights.

*	FREEZING LEVELS
1-3000 ft N, 2-4000 ft S Wed
2-4000 ft N, 4-6000 ft S The
3-5000 ft N, 5-7000 ft S Fri except lingering near the 
surface in the Cascade passes and along the lower east 
slopes night and morning 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

$$