First 90 Degree High?

August 17, 2011

I decided to change the 88 degree high on Saturday to 90 this evening based on two things:

1.  There appears to be a weak thermal trough west of the Cascades on Saturday now, pulling a light easterly flow over the Cascades and through the Gorge.  The UW’s WRF-GFS surface pressure map for 5pm Saturday is the image above…you can see what I’m referring to.

2. Models have warmed 850mb temps a bit…both the NAM, GFS, and WRF-GFS show temps between 18-20 degrees C. over Portland Saturday afternoon.

Those two factors may be enough to push us to 90 degrees.  The surface flow goes flat on Sunday, which might drop us back a few degrees.  It’s not tough for that to happen in late August.  With the rapidly decreasing daylight and long nights you need some offshore flow to get it up to or above 90 degrees (generally) in the afternoon.

So isn’t that exciting, supposedly it’s a big deal, even though in a normal year we’d be excited about the first 90 in May!

As I mentioned in last night’s post, it sure looks like we are breaking out of the big cool West Coast trough for the first time in 6 months!   Look for a continuation of warmer than average weather next week.  Even the ECMWF is a bit warmer than 24 hours ago.  The GEM and GFS are very warm (quite hot in the Canadian’s case) through all of next week.  The long-delayed Pacific Northwest Summer of 2011 is here.

Here’s a graphic showing total area burned in the State of Oregon the past 8 summers.  You can see the effect of this cool summer (so far of course):

Chief Meteorologist Mark Nelsen