Hang onto your hat as a strong jet stream sets up shop over our area, delivering stormy, dynamic weather. Stormy conditions are developing across the region as warm frontal moisture pushes into the area from the SW. Snow levels will start low this morning and climb through the day, reaching 4000-5000' for the central and southern WA Cascades, Olympics and Mt Hood by the afternoon, and 3000-4000 for the north Cascades. Precipitation rates will become quite heavy near and south of Hwy 2 in the afternoon, with several inches of snow/hr. Winds will also spike, becoming extreme in most areas this afternoon. The NWS has issued a blizzard warning later today for many areas for heavy snow and poor visibility.
Peak storm intensity and warming will occur this evening, and then a cold front will sag south tonight and snow levels will quickly fall. By Thursday morning, we'll still have heavy steady precipitation from about Hwy 12 and south to Mt Hood and snow showers further north. Mt Hood will likely see 2-3" of water in 12 hrs overnight! A convergence zone may boost snowfall totals near the Mt Loop Hwy and Stevens Pass late tonight through Thursday morning.
On Thursday, we'll have snow showers in good post-frontal westerly flow across the area. West winds will be strong in the north, and still extreme for southern areas. The heaviest precipitation will still be down near Mt Hood. A weak atmospheric river pulse will begin to flow back into the WA/OR border later Thursday taking aim for Thursday night/Friday.
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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Wednesday
Light snow in the morning, then stormy with extreme winds and moderate to occasionally heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the early evening, then moderate snow showers late evening midnight. Extreme winds.
Wednesday
Light snow in the morning, then stormy with extreme winds and moderate to heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate to occasionally heavy snow showers after midnight. Extreme winds.
Wednesday
Light snow in the morning, then stormy with extreme winds and moderate to heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate to occasionally heavy snow showers after midnight. Extreme winds.
Wednesday
Light snow in the morning, then stormy with extreme winds and heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate to occasionally heavy rain and snow showers after late tonight. Heaviest precipitation near and south of Hwy 12. Extreme winds.
Wednesday
Light snow in the morning, then stormy with extreme ridgeline winds and moderate to heavy rain and snow in the afternoon. Light E winds at Pass level in the morning becoming strong W in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate to occasionally heavy rain and snow showers after midnight . Extreme W winds at ridgeline, strong at Pass level.
Wednesday
Light snow in the morning, then stormy with extreme ridgeline winds and moderate to heavy rain and snow in the afternoon. Light E winds at Pass level in the morning becoming strong W in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate to occasionally heavy rain and snow showers after midnight . Extreme W winds at ridgeline, strong at Pass level.
Wednesday
Light snow developing in the morning, then stormy with strong ridgeline winds and moderate to occasionally heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate rain and snow showers heaviest near the crest after midnight . Extreme winds.
Wednesday
Light snow developing in the morning, then stormy with strong ridgeline winds and moderate to occasionally heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow in the evening, then moderate rain and snow showers heaviest near the crest after midnight . Extreme winds.
Wednesday
Light snow in the morning, then stormy with strong ridgeline winds and moderate to occasionally heavy rain and snow in the afternoon.
Wednesday
Night
Stormy with heavy rain and snow. Extreme winds.
Wednesday
Stormy. Moderate rain and snow becoming heavy late morning. 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).