Three Warm Days Ahead, Then A Saturday Soaking

May 26, 2020

10pm Tuesday…

A shorter blog post tonight since we have a very straightforward weather setup the next 5 days.

Skies are mainly clear this evening and should remain that way through Friday. Maybe not totally blue sky; we’ll likely see thin high clouds at times Thursday and Friday.

The atmosphere overhead warms tomorrow through Friday as strong upper-level high pressure builds over the western USA. Stockton and Sacramento (California) were 105 & 103 today; both records for the date.

The combination of a much warmer atmosphere overhead, then a switch to (very weak) offshore flow Thursday, means we get close to 90 both Thursday and Friday. That’s very warm, but definitely not hot. Notice we won’t be near record levels except Friday

That 100 degree record for May 28th is the first day PDX has ever hit 100 and also the only 100 degree record in May.

Saturday is beginning to look interesting. A cool upper-level trough suddenly scoots north along the West Coast Friday night and Saturday. There is a LOT of subtropical moisture with this one, check out the precipitable water image for Saturday. Anything over 1.0″ is juicy for us. Up around 1.5″ is really wet. This isn’t precipitation, but a good indicator of total column moisture through the atmosphere.

How much rain could we be looking at Saturday? It seems clear that SOMEWHERE in western Oregon will get nailed with an inch or more. Each model is a bit different with the rain bullseye. Plus it’s still four days away. Check out the GFS, GEM, & ECMWF

Will we get thunderstorms with the rain Saturday? Possibly…TBD. It depends on how things line up. The general pattern is correct, but models don’t seem too excited about widespread thunder west of the Cascades Saturday. We’ll see.

Sunday through Tuesday look quieter and mainly dry. Expect typical early June weather as we head into early next week.

Enjoy the warm sunshine these next three days, and be prepared for some downpours at some point Saturday. I’ll be back at work Sunday. A few extra days off this summer.

Chief Meteorologist Mark Nelsen