The Daily Cycle of Coastal Low Clouds and Flowing Fog
During the middle to late spring, the northeastern Pacific fills will low clouds, as illustrated by the visible satellite image from two days ago (shown below). And during fair-weather periods, as we have experienced during the past week, there is a daily rhythm of clouds along the coastal zone east of the Cascade crest, with clouds pushing in overnight and burning back during the day. Consider what has happened during the past day. Last night at 5 PM, there were lots of low clouds along the coast and a tendril of stratus/fog extending into the Strait of Juan de Fuca But overnight, the low clouds surged inland, as shown by the image at 7 AM. Coastal river valleys filled with clouds and stratus and fog pushed eastward into the Strait of Juan de Fuca, the Chehalis Gap (south of the Olympics), and along the Columbia River Valley. Central Puget Sound was fog free this morning as were the western slopes of the Cascades. By noon, the low clouds had pulled back to the coast And there wa