It's snowing and blowing across most of the forecast region this morning. Several weather stations stacked up 4-8 inches overnight, with Mt Baker pulling in almost a foot and a half in the last 24 hrs! Steady rain and snow turn showery this morning as the focus of the storm shifts towards the WA/OR border. Moderate to strong winds should also ease as the precipitation starts to let up. The glaring exceptions to this trend are areas near Mt Hood, Mt Saint Helens, and Mt Adams . Expect stormy conditions to persist all day with periods of heavy snow and strong and gusty winds.
By this evening, only a few isolated showers are left, mostly near and south of I-90. The main event is much further south, where the system forms a narrow E-W band of precipitation trained right up the Columbia River Gorge. Weather models are still uncertain about the exact positioning of this feature, which has major impacts on both precipitation and snow levels. There's a stark difference north and south of the main axis of precipitation. If it drifts north, warmer air will work its way into the Mt Hood and West/East South Zones. If it pushes further south, colder air can pull into the central Cascades.
The ripple effects from this uncertainty ripple into Tuesday morning. Places that saw rain and snow overnight should continue to draw out precipitation. The jet stream to our north pushes south during the day, combining moisture from Canada with the lingering system around Mt Hood. This should increase snow showers for the west slopes and passes on Tuesday afternoon. Cool northwesterly flow helps snow levels slowly drop below most trailhead elevations.
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
Rain and snow showers in the morning, then sun breaks and clearing. Moderate SW winds becoming light and variable.
Monday
Night
Partly to mostly cloudy with a few stray showers in the southern Olympics.
Monday
Rain and snow in the morning, quickly turning showery. A few sun breaks possible in the afternoon. Moderate SW winds becoming light.
Monday
Night
Partly to mostly clear with light winds.
Monday
Rain and snow in the morning, becoming showers. Moderate SW winds decreasing.
Monday
Night
Partly to mostly cloudy with a few showers, mainly in the evening.
Monday
Rain and snow in the morning, turning showery for the northern half of the zone. Steady precipitation near Mt Saint Helens and Mt Adams. Moderate and gusty WSW winds decreasing.
Monday
Night
Showers near and north of Hwy 12. Moderate to occasionally heavy rain and snow further south. Much windier conditions near Mt Saint Helens.
Monday
Snow in the morning, becoming showery. Light to moderate WSW winds decreasing.
Monday
Night
A few showers in the evening, then mostly cloudy. Light easterly flow developing at Pass level.
Monday
Rain and snow in the morning, then becoming showers. Moderate WSW winds decreasing.
Monday
Night
A few showers, mainly in the evening. Light easterly flow developing at Pass level.
Monday
Snow, mainly in the morning, then scattered to isolated showers. Sun breaks possible in the afternoon. Moderate SW winds turning W and decreasing slightly.
Monday
Night
Partly cloudy with some low clouds and valley fog.
Monday
Snow in the morning, quickly turning to showers. Moderate SW winds, turning W and decreasing slightly.
Monday
Night
Cloudy to the south with a few isolated showers in the evening. Mostly cloudy and dry to the north.
Monday
Rain and snow in the morning, turning showery. WSW winds decreasing.
Monday
Night
Rain and snow overnight with generally light winds.
Monday
Stormy with periods of heavier precipitation and gusty moderate to strong SW winds.
Monday
Night
Stormy with periods of heavier precipitation and gusty moderate to strong SW 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).