Monday was a day to retain in your memory, at least for a while, as it appears we may be heading toward a progressive weather pattern with a few dry days in between bouts of autumn rainfall.
A weather system was on track to bring some light rain during the afternoon and evening hours locally and lowering the freezing level to where the Cascade passes will see snowflakes in the air. Of course, the good sticking snow will be near the timberline areas of the Cascades, but lower at times.
Vancouver saw it lowest temperature in nearly six months early Monday with a low of 37 degrees. That’s the coldest since April 29, when it was 36 degrees. The outlying areas had lows at freezing and below with widespread frost from Brush Prairie, Battle Ground, Yacolt and Amboy. Reports of frost came from the La Center area as well. I bet many pumpkins were topped with frost.
We could see lows into the 30s and below later in the week as skies clear under a cold air mass Friday and Saturday. Meanwhile, an unsettled pattern remains Wednesday through early Friday. Showers and even thundershowers are in the forecast with mountain snows. The coast should begin to have overnight thunderstorms tonight and into the western valleys Wednesday.
Are we done with 70-degree high temperatures? I certainly do not see any heading our way this week, and after next week it would be rare to have a high of 70. Sweet memories.
A reader asked me how the ground could be covered in frost when the air temperature is above 32 degrees? The official height of thermometers for outside air temperatures is approximately six feet above the ground. During a relatively clear and calm night, there is good radiational cooling to space and the ground cools off rapidly. In such situations, the observed air temperature can be 2 to 8 degrees warmer than the surface.
Monday’s lows in Western Washington were in the 30s mostly; the lows near the water along the coast and Puget Sound were in the 40s. Eastern Washington was colder, with lows in the 20s and 30s. Deer Park took honors at 20 degrees.
We are sliding downhill on a steep slope to winter now.
Patrick Timm is a local weather specialist. His column appears Tuesdays, Thursdays and Sundays. Reach him at http://patricktimm.com.