In the lowlands of Western Washington, we’ve been plagued by several days of “May Gray,” as onshore low-level wind flow from the Pacific Ocean has pushed clouds into the Puget Sound region.
Meanwhile, moisture moving in aloft is being lifted by the encounter with the Cascades, and the result was a spectacular display of lenticular clouds near and east of the crest on Wednesday evening.
These lens-shaped lenticular clouds occur when moist air is pushed upward across the Cascade crest, and then the flow of air subsequently descends on the leeward, or eastern side of the mountain range.
The moisture in that air flow condenses into a cloud, but since air is constantly moving along an undulating flow (up and down) at and beyond the mountains, the lenticular clouds seem not to move much at all.
Despite that appearance, air is flowing through the cloud! These cloud features are called “standing lenticular clouds” aS the clouds themselves seem to be standing still!
Often, we also see these lenticular clouds over Mount Rainier, like a cap or a “hat.”
Meteorologists of today and people for centuries have recognized lenticular clouds as a potential sign of rain on the way, as moisture usually increases at these levels of the atmosphere before rain clouds nearer the surface can gather.
In the case of Wednesday’s lenticulars, there won’t be enough moisture in the few days to follow to produce much more than some patchy morning lowland drizzle!