An elongated, weak trough extends from an Aleutian low to our coastline. The associated upper-level front brings a round of mostly light rain/snow to the region today as it lifts NE. Steadier precipitation focuses on the Olympics and southern Washington Cascades during the morning and northern Washington Cascades in the afternoon. Areas behind the front can expect an increased SW flow, light rain/snow shower activity, and a slight bump in temperatures late in the day, but snow levels should remain below the major mountain passes. Although the front is reasonably weak, E winds should help enhance snowfall along the E slopes of the Cascades relative to your typical storm. We expect 3-8" of snow by the end of the day for Mt. Hood, Paradise, and the southern Olympics with 1-5" at most other locations.
Light rain/snow showers taper during the evening behind the first front. By late evening, a stronger frontal system also lifting NE begins to impact the Mt. Hood area. Moderate rain and snow spread throughout the region overnight. Expect an accompanying more significant round of southerly winds with moderate E winds peaking in the early morning hours.
Moderate rain and snow transition to showers by the afternoon. Expect the potential for a shift to rain at Snoqualmie Pass level as snow levels bump up to around 3500 ft upper-level SW winds overwhelm weakening low-level easterlies. Thursday night through Friday, we expect around 8-14" of snow for Mt. Hood, Paradise, and Mt. Baker with slightly lower amounts elsewhere.
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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Thursday
Light rain and snow (moderate in southern Olympics) tapering to showers in the afternoon.
Thursday
Night
Very light rain and snow showers in the evening, then light rain and snow returns.
Thursday
Light snow developing from late morning onwards, potentially becoming moderate during the afternoon.
Thursday
Night
Very light rain or snow showers in the evening, then light rain/snow returning by morning.
Thursday
Light snow developing from late morning onwards.
Thursday
Night
Very light rain or snow showers in the evening, then light rain/snow returning by morning.
Thursday
Light to moderate rain and snow becoming showery late in the day.
Thursday
Night
Tapering rain/snow showers in the evening, then moderate rain/snow develop overnight.
Thursday
Light snow developing from late morning onwards. Light to moderate ridgeline and E flow at the Pass.
Thursday
Night
Light rain/snow showers in the evening, then light snow develops overnight. Light ridgeline and E wind at the Pass becoming moderate overnight.
Thursday
Light to occasionally moderate snow developing from late morning onwards. Light to moderate ridgeline and E flow at the Pass.
Thursday
Night
Light rain/snow showers in the evening, then light snow develops overnight. Light ridgeline and E wind at the Pass becoming moderate overnight.
Thursday
Cloudy, then light snow developing by noon and increasing during the afternoon.
Thursday
Night
Light snow showers, then light snow.
Thursday
Cloudy to start, then increasing light to occasionally moderate snow.
Thursday
Night
Light snow showers in the evening, then light to moderate snow overnight.
Thursday
Increasing light snow.
Thursday
Night
Light rain or snow showers in the evening, then light to moderate rain/snow overnight.
Thursday
Moderate rain/snow tapering to light rain/snow showers by the afternoon.
Thursday
Night
Light rain/snow showers, then moderate rain/snow with ridgeline winds becoming strong.
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).