The big holiday weekend is approaching quickly! Last year was the 2nd warmest Memorial Day Weekend on record in Portland. That sure isn’t happening this year!
We have seen some warmer weather lately which has been nice. I’ve been able to work in the yard and garden sans mud. But May is still running (so far) the coolest since 2011.
Those numbers are for Portland, but I checked Salem which has been influenced less by the urban heat island. This month was close to the average temperature from the early 1960s to early 1980s. That WAS a cool period, but the point is that this “chilly May” isn’t really all that bad and we’ve sure seen it before.
We’ve all had a chance to get outside and enjoy dry weather for several days now. No measurable rain the last 4 days at PDX is the first time we’ve seen 4 consecutive totally dry days since early February! A few passing showers have dropped a trace today, with some of you picking up measurable rain this evening. Definitely more than I expected. Of course we picked up our typical May rainfall in the first half of the month:
High pressure strengthens a bit tomorrow and Thursday for warmer temperatures. I expect low-mid 70s both days. But then things are going downhill once again. The warm upper level ridge overhead will be replaced by a wet westerly jet stream by late Friday. Even California will get some showers…unusual in late May
By Monday, a chilly upper-level trough is sitting over the western USA. We will be on the cool side of that jet stream Saturday, Sunday, and Monday.
Right now it appears we won’t see that many showers Friday, but an organized (& wet) system comes through the region Saturday. Showers may even show up in the driest parts of central & north-central Oregon Saturday. Then expect lots of leftover showers Sunday. The good news? Most of the cool/wet airmass has moved to the south and east by Memorial Day itself. That means the 3rd day of the weekend could be best.
Weather this long weekend might be better along the beaches…not so many “pop-up” showers Friday and Sunday near the chilly ocean water. This is what I’m thinking for the northern Oregon and southern Washington coastline
With a cold airmass over us through the weekend, higher elevations are NOT the place to be. Expect snow as low as 5,000′ during the overnight hours. Passes will be fine, but it’s a cold/wet camping experience at the Cascade lakes!
By the time May ends and June arrives (Wednesday), the cold trough is gone and that means much warmer and more typical weather.
Just 4 days later the Starlight Parade is on tap…it’s too far out to see if another trough will be dropping in for a visit. For now it seems safe to say that we’ve got a few days of showers from late Thursday through Sunday, then drying the middle/latter part of NEXT week. You can see the gap in the ECMWF ensemble chart
1) A cool and somewhat showery weekend is on tap across the ENTIRE Pacific Northwest. But not a soaker every day
2) Wettest should be Saturday and Sunday. Much more reasonable (or mainly dry?) Friday and Monday
3) Expect mountain snow down to 5,000′ at times
4) Even the driest parts of the region in the Cascade rain shadow (Central Oregon) will get at least a few showers
Chief Meteorologist Mark Nelsen