As I write this blog around 6 p.m., sea air is rolling in west of Washington, with strong northwesterly winds pushing against the Juan de Fuca Strait.
At Race Rocks, south-southwest of Victoria, BC winds of only 48 mph and UW WRF’s latest forecast model predicts strong westerly winds, reaching over 40 knots, in the east strait at 8pm (see forecast map below).
We are currently going through a push on shore or sea and the cool, dense sea air is moving in at a low level causing sea level pressure to rise. Because the Falls prevent most of the cool air from moving eastward, the pressure remains lower east of the Falls.
The result of the low-level sea air indicator is therefore a large pressure differential (or gradient) over the Falls, as exemplified by the 8 a.m. sea level pressure forecast on Thursday. Fourth (see below). These contours are constant sea level isobars, and you’ll notice a lot of them on the Cascades, where the pressure is changing rapidly.
Danger
But there’s a problem. As the cool air in the west deepens, some can push eastward through the Cascades, accelerated by the large difference in pressure. The air then accelerated as it descended the slopes east of the Cascades causing strong winds.
And there we go to danger. A popular indicator of fire hazard levels created by some USDA Forest Service employees (including Brian Potter of the Seattle FS office) is an index known as HOT-DRY-WINDY (HDW). ), which is basically wind speed multiplied by a measure of atmospheric dryness. HDW’s forecast for tonight (Tuesday 8 p.m.) is threatening, with high values across and downstream of the eastern slopes of the Washington Cascades (see below).
Green/yellow/red are the most threatening. This high dry-hot wind index together with dense grass creates the potential for fire. The folds need to be careful to avoid catching fire.
With cool sea air settling to the west, temperatures will be at least 10 degrees lower on Wednesday, and the weather this week will be near perfect west of the Cascade (dry and above 70 to low of the Cascade). 80s). No nasty heat waves.
We have suffered this spring … not the payback period. 😁
