A parade of storms will bring more rain and snow to the Northwest throughSunday. The influx of Pacific air will cause snow levels in the mountains torise over 6,000 feet. Rain was already falling Thursday at Stampede Pass,Wash., which is at nearly 4,000 feet. Rainfall will be heavy at times,especially on the upslope sides of the mountain ranges. This combined withsnowmelt will be enough to cause some river flooding over the weekend.There will also be an increased danger of avalanches, which is a commonoccurrence in the Northwest whenever there is too much snow and/or asignificant thaw. Avalanches happen when a large mass of loose snow slides offhard-packed snow beneath it. Rain worsens the situation by making the surfacelayer of snow heavier, as well as acting as a lubricant between layers.

During the next few days, a sharp boundary between arctic and Pacific airmasses will extend from central British Columbia toward northeastern Montana.

South of this front is where all the rain will be; to the north, it will remainvery cold and snowy.

Story by AccuWeather.com Senior Meteorologist JohnKocet.