Back to Hot, Plus Humid This Week

August 6, 2017

10pm Sunday

Today was MUCH more pleasant with a relatively “chilly” start.  Many of us started way down in the 50s…ahh, nature’s air conditioning

PDX Observed Low Today

At the same time morning clouds covered much of the metro area.  At noon today it was only 74 degrees in Portland!  Yet we eventually made it up to 88 this afternoon.   So as you know we sure won’t break any hot streak here in Portland…this heat wave will go down as a somewhat typical heat wave, but with two VERY hot days right in the middle.  Down in Salem the 90 degree streak continues and the next two days should establish this hot spell as the longest in Salem’s history:

90 Degree Days Heat Salem

We sure did get a thicker marine layer today.  That kept temperatures down, but tomorrow that layer should be thinner under a building upper-level ridge.  There will be no offshore easterly flow this week, but the hot atmosphere overhead will remain with a weak onshore flow through Thursday.  That will keep those 100 degree temperatures away, but inject plenty of moisture for a more “humid experience” this week.  Dewpoints are in the lower 60s in the metro area this evening; unfortunately I think we’ll see lots of those 60-65 degree dewpoints through Thursday.  It won’t help that there will be lots of moisture coming in overhead as well.

Hot Headlines2

Looking farther ahead, it appears that for the first time in almost a month we have a chance for a cool/showery weather pattern.  Remember, I said CHANCE.  For days models have been telling us the ridging overhead will break down this weekend and beyond.  Note the big drop in 850mb temps on the ECMWF


The blue/red lines are temperature in celsius at 5,000′.  Check out the return to normal temperatures by next Monday.  And there’s good agreement among a majority of the ensemble members that we’re turning a corner to cooler weather.

What about rain?  Here’s an interesting graphic from the GFS showing total rain accumulation through the 2 week period from each of its 21 ensemble members.  Note 12 of 21 (over half) produce measurable rain in Portland before eclipse day (21st)


Before you panic and worry about that $500 you plunked down for one dusty campsite for one night in a field…keep in mind this is a “total” accumulation of rain through the two-week period.  A better view might be from the ECMWF 24-hr chart:


This one shows all 51 ensemble members from that model.  Each member is a horizontal line again, but in this chart you only see 24 hour periods that contain rainfall.  Any color means at least .10″ rain in a 24 hour period.  This is for Salem as well, not Portland.  Now things don’t look so bad do they?  Just a chance for showers here and there.  The main message here?  Models are telling us NEXT week will be much cooler and a few of us could actually get some rain showers.

It’s still too far away (15 days) to get a good idea what might happen for eclipse day itself.  More on that later this week or next weekend.

Chief Meteorologist Mark Nelsen