For most of the first week of May, the Cascades have been a stark dividing line: often gray and chilly to the west, and warm, dry, and windy to the east.
This is a typical weather pattern in the spring, when high pressure over the northeast Pacific creates onshore breezes — wind that flows from the chilly offshore waters inland. This air holds plenty of moisture and often has abundant low clouds and light precipitation like drizzle. The Cascade range is a “wall” that the moist west-to-east flow of air hits.
The clouds on that wind flow tend to collect in the interior lowlands, especially around Puget Sound. Meanwhile, the air flow that tops the Cascade passes then rushes downward to lower elevations off the eastern slopes and that wind accelerates.
Wind gusts in Ellensburg and Wenatchee topped 40mph on Friday.
Fortunately for both sides of the Cascades, the weather pattern is changing, and the onshore flow won’t be as strong over the weekend. In addition, increasing high pressure aloft will give a little downward force to air in the atmosphere.
These changes will allow for less cloud cover on Saturday morning in the lowlands of Western Washington (though there will be some) and less wind east of the Cascade range.
Now, some high clouds will likely increase over the area later Saturday through Sunday but not enough to spoil what should be a pleasant springlike weekend, instead of the summerlike warmth we experienced to start the month.
Highs in the lowlands of Western Washington Saturday should reach the mid 60s to lower 70s. East of the Cascades, we should see more 70s and even a few 80s. Temperatures will cool a bit Sunday but remain warmer than average.
Rain chances look slim and fire danger increases through at least the first few days of next week. We’ll monitor slight rain chances around midweek but better odds of precipitation look to come into the picture toward the middle of May.