An Okay Weekend

July 2, 2010

I think it will only be an “okay” weekend.  Not totally sunny; comfortable during the day, but a bit chilly for fireworks, and even the threat of a shower Sunday evening as close as Mt. St. Helens and Olympia-Chehalis.  But at least it won’t be a drizzly/drippy 4th…good news there.  And to be honest, a 90 degree day sitting on the pavement waiting for a parade isn’t exactly great.  So it goes…

The weekend has begun for most (not those of us that work until 11:32pm) and it should be pleasant.  I don’t have any dramatic changes to the forecast, either short or long term.  I added more clouds to Monday since the trough is a little slower to depart.  That 78 may be 3-5 degrees too high too…we’ll see.

Long Term: Very interesting.  The 12z ECMWF came in blazing hot again with the highest 500mb heights and 850mb temps up around +23 to +24 deg!  That with offshore flow is up in the 100-103 degree range.  The 12z and brand new 00z GFS are similar (to each other).  500mb heights are a bit lower than the ECMWF, but the model continues to generate unusually hot surface temperatures for the heights and 850mb temps that it’s showing.  Basically from my experience the two don’t seem to match up.  Looking at the GFS runs, I’d go about 87-90 degrees max Tuesday-Friday (or beyond).  But a closer inspection reveals no onshore flow through the period, and easterly flow at times, in fact a nice thermal trough west of the Cascades Wednesday-Thursday doesn’t really move east of the Cascades through next Sunday!  That must be why the surface temps are unusually warm.

The upcoming pattern looked familiar to me so I looked it up…sure enough, early June 2003.  We had highs between 91 and 98 for 4 days in a row with 500mb heights at/below 585dm and 850mb temps only to +20 or so.  Very similar situation with a cool upper-level trough to our east giving higher pressure east of the Cascades for several days.  So this setup has occurred in our past.  Based on that I put in 4 days at/above 90 degrees.  However it could easily end up warmer than the 92 our 7 Day forecast shows.

Fireworks: What is billed as the state’s 3rd largest fireworks display is going on again this year up in Corbett and the Fun Festival.  It could be…I’ve never sat through such a long display…the last few years it has run maybe 30-40 minutes.  I’ll be there this year.  The entry fee goes to a good cause (schools and sports), I have some sort of garbage cleanup or burger-flipping duty in the early evening with the Youth Sports, not sure which.  So you might run into me there.  My advice…do NOT park near the Scenic Highway and definitely take side roads back into Gresham or Portland, even if you have to drive all the way east to Bridal Veil or south to Dodge Park.  I heard some people were stuck for an hour in the parking lots last year!

Happy Fourth of July!

Chief Meteorologist Mark Nelsen