Weather Synopsis for Sunday & Monday

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.