We’re quickly approaching the end of May; it’s been a warm month!  Today we got rid of the marine clouds early leading to a much warmer day

Todays Observed Highs OrWa 2017

Check out the May stats so far…

Month Climate Temps Calendar

Notice only two days were cooler than average, and of course that first full week of the month was like July weatherwise.  Memories of cool/wet springs have faded (for now) west of the Cascades; we haven’t seen a cool/wet May in 7 years!  Check out rainfall as a percent of normal across the West.  We are alone in western Oregon and Washington.  Most of the West has been quite wet.  Check out those spots in the Southwest with 4X the typical May rain!

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The setup this spring hasn’t changed all that much since late winter (February).  Ridging to the west and northwest of us, and troughing (a dip in the jet stream) over the rest of the western USA.


By the way, this is also the reason for the persistent stormy pattern across Tornado Alley.  A southwesterly jet moving across the Great Plains and Mississippi Valley plus cool air pushing across the Plains from time to time.  Lots of moisture = flooding and big thunderstorms.

So what’s ahead for Portland and other areas west of the Cascades?

  1. Little or no rain through at least NEXT Wednesday.  Of course a thick marine layer can produce drizzle, but that’s all I see.
  2. Temperatures remain above average over the next week.  Marine layer depth will influence whether we have a high of 70 or as warm as lower 80s at times.
  3. All clear weatherwise for Starlight Parade and Timbers home opener Saturday.  Thorns game should be great as well Sunday.
  4. Time to plant the rest of your warm weather veggies if you haven’t yet.  It’s okay even in the foothills where it’s cooler/wetter than the cities.

The weather pattern evolves just a bit over the next week.  For now there is a strong upper-level ridge sitting just to our north.  That’s the reason we’re seeing early fires in British Columbia and Alberta; you’ve probably noticed the hazy skies?


By Saturday the ridge is a bit stronger and more directly overhead.


By next Tuesday (in this example using the GEM) the ridge is still there, but “flattened” a bit.   This is a classic early summer weather pattern; no hot weather but temps above average and dry.


I have high confidence with the dry spell, see the GFS ensemble rain outlook for the next 15 days.  Each horizontal line is one of the ensemble members.  The total at the bottom (in green) is the average of all those members.    Notice only a few produce showers late next week or weekend of 8th/9th.


The ECMWF is similar; no ensemble member produces rain until at least next Thursday.  This model is a bit wetter right around the Grand Floral Parade day (8th).


Enjoy the dry start to June, hopefully we can get one more (brief) soaking before we get to July.

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