What’s Ahead?

May 31, 2010

The summer weather (July & August) that followed the 5 wettest Mays in PDX history.

So what happens after the 3rd wettest May in Portland’s history?  To be honest I don’t think anyone could really tell you; but I do think we can probably rule out one thing.  People have asked me if this means a cool and wet summer.  That appears unlikely based on past history here.  I looked up the June, July, and August weather that followed our 5 wettest Mays on record here at PDX.  Notice that only one was really a “bad” summer;  1993 was widely known as the “summer of green tomatoes” here.  Lots of cloud cover and marine air; plenty of rain as well.  Luckily that was the one summer in my adult life in which I wasn’t living west of the Cascades.  I was working for a private weather company in Hood River at the time…that was probably the sunniest summer I’ve ever experienced because they don’t get the low clouds over there east of Cascade Locks.

Notice also that two of those very wet Mays were followed by horrendous fire seasons over and east of the Cascades.  The Blue and Wallowa mountains were nailed by historic wildfires…likely due to lots of green growth in the last spring that dried out later in the summer heat.  The same thing is happening this year; well above-average rainfall in normally dry areas eastside.  I know the dryland wheat farmers are ecstatic over the regular dousings from either thunderstorms or stratiform precipitation this month.  And the chilly weather keeps the evaporation down too.  Should be the best weather conditions for those folks  in north-central Oregon in 10-12 years.

Not much weather on the way Tuesday, but what a system coming in Wednesday!  Looks like a (brief) wintertime pineapple express….high precipitable water, high freezing levels, strong southwest winds in the upper levels etc…  I don’t see any chance for river flooding since the rainfall is pretty much gone by late Wednesday afternoon.

The second system coming through late Thursday night and Friday morning is sure one to watch.  Latest models swing a deep low up the coastline with the usual strong southerly wind along the coast and more rain; hard to believe it’ll be June 4th!   We “laid low” on the 7 day forecast for any significant warming Sunday and Monday.   Earlier models have been very warm Monday and Tuesday, now I see the 00z GFS is cool, but the GEM is still real warm.  Seems to be a trend for some ridging along the West Coast, but when it takes hold is most definitely yet to be decided.  If we make it past next Wednesday with no 80 degrees it’ll be the latest ever here in PDX-town.  The “record” isn’t exactly something that will go down in history (who even knew that record existed?), but a good benchmark for a cool spring.

Chief Meteorologist Mark Nelsen