Warm frontal precipitation, the final component of our atmospheric river period, will increase across the area today, with heavier precipitation in the afternoon. There's still quite the spread in the precipitation forecast for today, but the central and north Cascades will bare the brunt of the storm. Several inches of snow accumulated overnight at mid-elevations in most areas, but unfortunately, snow levels will rise again today, turning snow back to rain at popular trailheads and ski-area bases.
A very strong cold front will smash through our region Tuesday night, creating stormy conditions with heavy precipitation and strong to extreme winds. The front should pass through the Cascades in the 1-3am time frame, with snow levels dropping quickly to 2500'. Before the frontal passage, the majority of the precipitation Tuesday night will fall as rain, at least at low and mid-elevations. Winds will be ripping through this period.
We'll finally see snowflakes return to lower elevations early Wednesday morning and continue during the day. Snowfall will accumulate along the west slopes of the Cascades and moderate to strong W winds will continue as well. An area of convergence should help boost snowfall totals in the Stevens/Mt Loop general vicinity. 6-12" of snow along the west slopes and Passes seems like a good bet, with slightly lower totals 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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Tuesday
Light rain and snow developing this morning and becoming moderate in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Light to moderate W Pass level and ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Light to moderate W Pass level and ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
Tuesday
Light rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate rain and snow and extreme winds.
Tuesday
Light rain and snow developing this morning and becoming heavier in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Tuesday
Night
Stormy with moderate rain and snow and extreme winds.
Tuesday
Light to moderate rain and snow developing this morning and becoming heavier in the afternoon. Strong ridgeline winds.
Tuesday
Night
Stormy with moderate to heavy rain and snow and extreme winds.
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).