rainy

10pm Monday...

Today was a nice day; brief morning clouds then afternoon sunshine.  A perfectly normal late August day with a high of 81 degrees.  It appears we’ll likely have more than our typical yearly allotment of 80 degree days.  In a normal year we get 56 days at/above 80 degrees in Portland.  Today was day #48.

80 Degree Days SO FAR

The weather pattern over the next 7-10 days continues to look somewhat on the boring side for meteorologists.  That’s except for Wednesday.  An surface low pressure system is developing well offshore.  It showed up very nicely on GOES-17 imagery just before sunset

Capture

The bulk of that system’s rain heads just north of us.  But there is an unusually high amount of moisture with this system.  Plus some of the highest sea surface temperatures I can remember are in place across the eastern Pacific offshore.  Buoy 89, about 100 miles west of Tillamook, is reading a water temperature of 67-68 degrees!

SST

Here’s a forecast from the ECMWF, giving us around 1/2″ rain Wednesday, with up to 1″ or so on the northern Oregon coastline.

web_ECMWF_Rain_18z

Some models are slightly wetter, some a bit drier.  The effect is the same

  1. ) Our very weak fire season will get beaten back once again.  As of this moment there is only one large fire actively burning in Washington and Oregon!  And that isn’t being actively put out since it’s in the Wallowa Mountains.  These occasional shots of light showers and higher humidity are helping out this summer.
  2. ) Everyone west of the Cascades gets at least a dust-settling rain.
  3. ) Southwest Washington, especially north of Longview, could see well over 1/2″ of rain, a nice late-summer soaking.

It’s quite clear that this is a one-shot deal.  Take a look at 50 members of the ECMWF ensemble run this morning.  Each horizontal line represents 24 hour precipitation from one of the ensemble members.  Then at the bottom you see the ensemble average.  It looks very dry Thursday through much/all of the last full week of August.

ecmwf-KPDX-indiv_qpf_24-6216000

All of the global models say the last full week of meteorological summer (next week) could be hot as well.  That said, MANY times this summer they have tried to shove a hot ridge of high pressure right up over the West Coast.  They were only right way back in early June.  This morning’s run of the ECMWF showed a hot pattern developing by next Monday

ecm_mon_26

And still there next Thursday, 10 days away

ecm_thu_29

Both maps are hot, even for late August.  We will see…

Chief Meteorologist Mark Nelsen

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