A Chilly July Airmass

July 12, 2010

A very interesting weather day across the Pacific Northwest.  A huge marine push last night, then a cool airmass plunging through the region bringing high winds to the east end of the Gorge and eastern Washington/Oregon.  Peak gusts of 50-60 mph in the eastern Gorge are unusual in July even there.  Today’s events were similar to a September cold front east of the Cascades.  Dewpoints are way down as well, not just eastside but westside.

To give you an example of how unusually chilly today was; consider it was partly-mostly sunny the last third of the day…and we STILL couldn’t make it to 70 at PDX.  The 850mb temp (temperature in celsius around 4,000′) over Salem this afternoon recorded by the weather balloon was only 6.4 degrees.  I checked our chart which includes all July days from 1997-2008.  That’s over 300 days; Today was around 285!  There have only been about 15 July afternoons out of 300 that were this cool.

Now that we have mostly clear skies and low dewpoints, temperatures are dropping like a rock.  40s will be widespread by morning with even PDX possibly approaching the record low of 48 degrees.  With such a chilly airmass overhead we won’t get the solid low clouds in the morning, more broken again like the 2nd half of today.  Still, maybe we can squeeze out a few degrees of warming.

Much better Wednesday and Thursday with higher upper-level heights as the cool trough moves east.

The BIG picture (3-10 days out) shows some sort of longwave trough lingering over the West Coast, possibly deepening gradually beyond the weekend.  That screams average to below average temps, but probably no rain.  Those of you looking for a mid July heat wave are out of luck!

Trip Report: Wayne Garcia, Shauna Parsons, and I spent three days up at Timothy Lake this weekend.  That was along with our 6 kids and spouses of course.  That was a lot of fun.  I’ve spent plenty of time at Trillium, Clear, and Lost Lakes, but never Timothy.  If you like mountain biking, the round-the-lake trail is a wonderful ride on a 75 degree day.  Maybe 15 miles or so, although I added a few miles by heading up on the pavement through Little Crater Lake campground.  Nice to jump in the lake afterwards.  Nobody got hurt, except my son flying off a dirt hump jumping his bike.  No more flip-flops while BMXing!  Weather was that perfect Cascade camping temperature…75-80 daytimes and maybe 50-55 at night.  Glad we weren’t there for the windy 60 degree temps today!

Chief Meteorologist Mark Nelsen