Another Round of Hot Weather Sunday-Tuesday

July 22, 2020

11pm Wednesday…

Today was far more comfortable west of the Cascades with high temperatures only in the low-mid 80s after morning clouds.

Expect more of the same tomorrow and Friday as marine air is in control westside. Nature’s air conditioning will keep us near/below 80 degrees through Saturday. That’s because weak weather systems (upper level troughs) keep moving by to the north in British Columbia. Here’s the view around 18,000′ on Friday from the GEM (Canadian) model showing that “dip” in the upper-level flow:

But see what happens by Sunday? An upper-level ridge pops up directly over the Pacific Northwest

An upper-level ridge this warm (590 dm heights) sitting directly overhead is heatwave material in July and August. So far this season we haven’t seen a hot ridge move right over the top of us. Models are forecasting +22 to +24 degree (Celsius) temperatures at 850mb (5,000′) over us Sunday and Monday afternoon. That’s also heatwave material. Third, a couple models produce easterly flow down off the Cascades Sunday, and to a lesser extent, Monday. The surface pressure map for Sunday shows what we call a “thermal trough” west of the Cascades.

If that develops, we could hit 100 degrees in this pattern. We’ll go slightly cooler and aim for 98 both days. Beyond that time, the ridging weakens and temps go back closer to normal by the middle of next week. Here’s our current Portland forecast:

That’s it for this evening…I’ve got a weekend plus a couple days of vacation coming so no blog post until at least next Tuesday. Enjoy the comfortable weather ahead of the hot weather early next week!

Chief Meteorologist Mark Nelsen