The storm was a little late last night resulting in lower precipitation totals than expected. However, based on the early morning weather station data, it looks like the firehose has turned on for most locations. Expect stormy weather today with periods of heavy precipitation, rising snow levels, and strong and very gusty winds.
An atmospheric river (AR) is currently aimed at the Pacific Northwest pumping a steady stream of moisture into the region. While precipitation will be heaviest in the Olympics, western Cascades, Passes, and Mt Hood, rain and snow should easily make their way across the crest and into the eastern reaches of the forecast area. Even if it's snowing at the trailhead this morning, that won't last long. Temperatures are already on the rise. Snow levels pushed above Snoqualmie Pass in the wee hours this morning. White Pass and Stevens Pass should follow suit by mid morning. Eventually, snow levels should rise into the upper elevations for most forecast zones. Cold air will try to hang in the Baker and Wa Pass areas. These cold air pools may be isolated to sections of the zone closest to the Canadian border. On top of the heavy precipitation and warming temperatures, wind speeds are also on the rise. Expect very strong to even extreme winds with significant gusts. Put all of these factors together and you have a tough weather day in the mountains.
The pattern continues into the evening hours. Eventually, the focus of the AR lifts a bit to the north. This will be most noticeable in the southern half of the region where precipitation should become lighter overnight. By Monday, the AR begins to weaken. Moderate to heavy rain and high elevation snow should continue for the Mt Loop Hwy and Baker regions, with noticeably less precipitation further south and east. Wind speeds should also ease as the storm weakens, but snow levels remain very high. Unfortunately, even as the storm winds down temperatures don't drop. We're in for an extended period of warm weather.
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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Sunday
Very stormy especially in the western Olympics. Periods of heavy rain and snow. Warming. Very strong and gusty SW winds.
Sunday
Night
Stormy with rain and high elevation snow. Strong and gusty WSW winds decreasing.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures.
Sunday
Night
Continued stormy weather with generally strong and gusty winds and periods of heavy precipitation.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures.
Sunday
Night
Continued stormy weather with generally strong and gusty winds and periods of heavy precipitation.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures. Rain and snow heaviest on the volcanoes.
Sunday
Night
Rain and high elevation snow. Very strong and gusty winds decreasing.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures. Snow turning to rain at pass level mid morning.
Sunday
Night
Continued stormy weather with generally strong and gusty winds and periods of heavy precipitation.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures.
Sunday
Night
Continued stormy weather with generally strong and gusty winds and periods of heavy precipitation.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation near the crest, and warming temperatures. Lighter precipitation with the occasional heavy shower further east.
Sunday
Night
Generally light rain and high elevation snow. Strong and gusty winds decreasing slightly.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation near the crest, and warming temperatures. Lighter precipitation with the occasional heavy shower further east.
Sunday
Night
Generally light rain and high elevation snow. Strong and gusty winds decreasing slightly.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation near the crest, and warming temperatures. Lighter precipitation with the occasional heavy shower further east.
Sunday
Night
Generally light rain and high elevation snow. Strong and gusty winds decreasing slightly.
Sunday
Stormy with strong and very gusty winds, periods of heavy precipitation, and warming temperatures. Extreme alpine winds.
Sunday
Night
Rain and high elevation snow. Very strong and gusty winds decreasing.
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).