It feels a bit like Groundhog Day with the same low pressure system from Sunday still here and affecting the region this morning. The surface low pressure has setup off the NW tip of the Olympic peninsula. Convective showers are rotating inland along the Washington and Oregon coast but losing steam as they approach the Cascades. Light snow can be found along the north and central Cascades along with more cloud cover. Areas along the west slopes of the Cascades, Hurricane Ridge and Mt Hood picked up 2-4" overnight, with 1-3" along the east slopes of the Cascades.
The northwest and central-west Cascades (Mt Loop) will see organized showers hang on through a good chunk of the day with more scattered shower activity elsewhere. A trailing and cold upper level trough will slowly shift inland today, shifting a cold unstable air mass closer to the Cascades. Light showers should start to pop back up in the early afternoon from about Hwy 2 and south. There may be a few isolated showers along the east slopes of the Cascades closer to the Cascade crest this afternoon.
Shower activity should taper overnight. An occluded front will rotate north on Tuesday, but won't reach the area until Tuesday night. This frontal boundary will extend from an upper low complex that's digging well of the California coast. While we wait for the front, look for increasing offshore flow and easterly winds Tuesday afternoon. Strong SE winds will extend up to the Cascade crest level and affect a large swath of the south and central Cascades. Light upslope snow and low clouds should develop along the east slopes of the Cascades during the day on Tuesday as well.
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 cloudy in the morning becoming partly sunny in the afternoon. Isolated showers all day.
Monday
Night
Partly cloudy in the evening becoming mostly cloudy after midnight.
Monday
Cloudy with light snow showers in the morning. Mostly cloudy with scattered light snow showers in the afternoon.
Monday
Night
Partly cloudy.
Monday
Cloudy with light snow showers in the morning. Mostly cloudy with scattered light snow showers in the afternoon.
Monday
Night
Partly cloudy.
Monday
Mostly cloudy with scattered light snow showers in the morning, becoming partly sunny with isolated light snow showers in the afternoon.
Monday
Night
Partly cloudy.
Monday
Cloudy with light snow showers in the morning. Partly to mostly cloudy with isolated light snow showers in the afternoon. Light east winds at Pass level.
Monday
Night
Partly cloudy.
Monday
Cloudy with light snow showers in the morning. Partly to mostly cloudy with isolated light snow showers in the afternoon. Light east winds at Pass level.
Monday
Night
Partly cloudy.
Monday
Cloudy in the morning in the morning with scattered light snow showers. Partly sunny in the afternoon with isolated light snow showers.
Monday
Night
Partly cloudy.
Monday
Cloudy in the morning in the morning with scattered light snow showers. Partly sunny in the afternoon with isolated light snow showers.
Monday
Night
Partly cloudy.
Monday
Cloudy in the morning in the morning with scattered light snow showers. Mostly sunny in the afternoon with isolated light snow showers.
Monday
Night
Partly cloudy.
Monday
Mostly cloudy with scattered light snow showers in the morning, becoming partly sunny with isolated light snow showers in the afternoon. Cloudier Timerline area.
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).