The same Puget Sound Convergence Zone that started last night is still with us this morning. The main convergence band had shifted south overnight, dropping up to 6 inches as far south as Crystal mountain and Paradise before shifting back north. Snoqualmie Pass was the winner with an additional 9 inches of new snow since yesterday afternoon. The convergence zone will continue to weaken and shift further north today, becoming more scattered in the afternoon. Strong westerly ridgeline winds for the south Washington Cascades and Mt Hood will slowly ease today.
An elongated upper level trough over much of central Canada continues to be the dominant weather feature for much of the country including us here in the Pacific Northwest. Cool NW flow aloft and a weak surface low circulation off the Washington coast will define our weather for the next 2+ days. Strong surface high pressure (1050+ mb) in NE British Columbia will slowly shift southward over the next few days. In the short term, this will allow the drip of colder air through the Fraser Valley. Combined with light onshore flow from weak surface circulation offshore, this should lead to more clouds and continue the chance for light snow shower over central and north Cascades, both sides of the crest. Fewer clouds and a lower chance of showers should be seen south of Mt Rainier down to Mt Hood and for the Olympics.
The coldest air of the season has arrived with mountain temperatures in the low 20s or teens. If you're heading out to the mountains expect a chillier week than we've seen all winter.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Monday
Partly to mostly sunny.
Monday
Night
Mostly clear.
Monday
Cloudy with scattered light snow showers. Sunbreaks possible in the afternoon.
Monday
Night
Mostly cloudy with isolated light snow showers.
Monday
Cloudy with scattered light snow showers. Sunbreaks possible in the afternoon.
Monday
Night
Mostly cloudy with isolated light snow showers.
Monday
Cloudy with scattered light snow showers in the morning, mostly cloudy with isolated snow showers in the afternoon. Moderate to strong west ridgeline winds decreasing in the afternoon.
Monday
Night
Partly to mostly cloudy with isolated light snow showers.
Monday
Cloudy with scattered light snow showers in the morning, mostly cloudy with isolated snow showers in the afternoon. Moderate west winds at ridgeline and Pass level decreasing in the afternoon.
Monday
Night
Mostly cloudy with isolated light snow showers. Light east winds at Pass level.
Monday
Cloudy with scattered light snow showers in the morning, mostly cloudy with isolated snow showers in the afternoon. Moderate west winds at ridgeline and Pass level decreasing in the afternoon.
Monday
Night
Mostly cloudy with isolated light snow showers. Light east winds at Pass level.
Monday
Cloudy with scattered light snow showers in the morning, mostly cloudy with isolated snow showers in the afternoon.
Monday
Night
Mostly cloudy with occasional light snow flurries.
Monday
Cloudy with scattered light snow showers in the morning, mostly cloudy with isolated snow showers in the afternoon. Moderate to strong west ridgeline winds decreasing in the afternoon.
Monday
Night
Mostly cloudy with occasional light snow flurries.
Monday
Mostly cloudy with isolated light snow showers becoming partly cloudy in the afternoon.
Monday
Night
Partly to mostly cloudy with occasional light snow flurries.
Monday
Mostly cloudy with scattered light snow showers west side of the mountain. Partly sunny east side of the mountain. Strong west winds decreasing in the afternoon.
The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.
The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.
The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.
*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.
Ridgeline winds are the average wind speed and direction over a 6 hr time period.
The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.
Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.
Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).