Clean Air Returns & Thunderstorms Tonight Eastside

August 16, 2018

9:40pm Thursday

Today has been refreshing…brief morning clouds and then cooler temps.  We hit 83 in Portland this afternoon; down from 89 yesterday and 90s on Monday and Tuesday.

High Temp Last 13 Days

Most noticeable is the cleaner airmass over us.  Everyone in the metro area is breathing GOOD air quality this evening


You probably noticed there is still high-level smoke overhead, evidenced by the yellowish sunshine.  Even that goes away Friday as upper-level winds turn westerly for a few days.

We are getting another push of marine air this evening and models show low clouds coming up mainly the Columbia River for a gray start in much of Cowlitz, Clark, and Multnomah counties Friday.  After that you can expect a very BLUE sky overhead since that smoke should be gone.

As expected, thunderstorms have fired up across central and eastern Oregon this evening.  Take a look at the 100+ cloud/ground strikes in the past half hour

KPTV 2017 Default Earth

Many of these are producing very little rain so obviously this is a huge concern for fire starts.  Hopefully new fires remain small.  I saw what appears to be a new fire producing a large smoke plume just southwest of Summer Lake earlier this afternoon on GOES-16 imagery.

What’s ahead?  Typical late August weather…a little heat, but cooler periods as well.  It’s pretty obvious we have passed the worst of summer.  That is normal for us.  Nights are getting longer; giving us cooler nights.  In fact even the middle of the metro area should drop into the mid 50s tonight and tomorrow night.  Nice.

There should be one more brief hot period Sunday-Tuesday, then cooling again later next week.  Notice the good agreement on the ECMWF ensemble chart; a peak around Monday/Tuesday, then quite a dip later next week before more warming.


Down here at ground level that translates to high temps back into the 90s early in the week and then back down around 80 (or below) a week from now.  This is what the same ECMWF model thinks Portland will look like over the next 10+ days


Rain?  Unlikely we’ll see anything other than sprinkles out of marine clouds the next 10 days.  Only 6 out of 51 ensemble members bring .10″ or more to Portland in the next 2 weeks.


Chief Meteorologist Mark Nelsen