Summer Really Kicks In

July 7, 2010

It was hard to believe we could jump into the 90s after shivering in the cold July 4th evening, but it slapped us in the face today!  We climbed from 57 to 95 in just about 10 hours or so here in Portland today.  Now after just a few hours of that, those 67-68 degree high temperatures seem very foreign don’t they?  It’s as if everything is right with our weather again and normal July weather has arrived.  Of course 95 degrees is not normal, but balance that out with much cooler weather over the weekend and next week and you get July in the Pacific Northwest.  I went out to grab a sandwich for dinner (a real simple guy), and noticed that it just didn’t feel extremely hot.  Maybe it was partly due to the lengthening shadows at 6:30pm, but the heat just didn’t seem so intense.  I have a feeling it’s due to the fact that our humidity was quite low this afternoon, even for here.  Dewpoints dropped down to around 40 degrees.  Just for fun I made a graphic to compare our weather with Chicago today.  Notice the overnight low and high humidity…yuck.  About 5.2 g/kg moisture here in Portland but over 15 g/kg in Chicago.  We don’t get much humid weather here because we have no “warm” source of moisture.  Anytime we get a significant influx of marine air, much chillier weather arrives too.

A challenging coastal forecast for today wasn’t it?  72 at Newport…at 7am, before it dropped to around 60 the rest of the day as a shallow SW surge of marine air moved north along the beaches.  But north of Lincoln City temperatures soared well into the 90s.  Astoria, Seaside, Tillamook…all between 93 & 95!  But as of 9pm that surge has made it all the way to the Columbia River.  No one within 5 miles of the coastline should get above 75 tomorrow…60-70 far more likely on the beaches.

Inland forecast is a bit simpler…a few degrees warmer tomorrow.  We hit 95 at PDX; add 3-5 degrees and you get 98-100.  We already had 98 in the forecast and of course I wanted to just bump it up two more degrees to make it a nice even 100, but on some of the graphics it’s a real pain to resize the forecast high to 3 digits, so I just left it at 98 because I’m too lazy to change the font size.  I’m joking (mostly), but I think any forecast between 96 and 101 at PDX tomorrow is reasonable.  The 850mb temp at SLE was right where it was supposed to be today (20.4 deg) at 00z.  Just a slight warming tomorrow, east wind early that backs off to calm in the afternoon, and 100 is most definitely possible.

I see very little inland penetration of marine air for Friday, in fact a hint of brief easterly flow in the lower atmosphere to start the day, so I bumped the high back up to around 95.  Appears to be a very nice marine push (northwesterly-type) for Friday night, so Saturday a good 10 degrees cooler for perfect low-mid 80s in Portland and probably AM clouds only to Kelso.  More likely some morning clouds on Sunday.

After a bit of a recovery in 500mb heights to around 588 dm. Sunday and Monday, a trough slides by to our north the middle of next week.  GFS is still much stronger with marine air dominating our weather again Tuesday and beyond, ECMWF is much weather with the trough.  We stuck with the warmer ECMWF.  There’s always tomorrow to see how models are doing…

Stay cool!  And a great picture of Wayne Garcia blowing on that vuvuzela coming up on the show tonight too!

Chief Meteorologist Mark Nelsen