Warmest Day of the Week

August 4, 2016

9am Thursday…

Today looks like a hot one.  I think most of the metro area will end up between 88-92 degrees.  For the first time in a few weeks we have very light EASTERLY flow over the Cascades and through the Gorge; that’s when air is flowing from land toward the sea.  I see the pressure gradient is about 0.5 millibar from Portland to The Dalles.  You can see the (light) easterly flow on the Troutdale profiler nicely this morning.

Capture

Current time is on the left side of the image, 48 hours back in time is on the right side.  Two things show up; note the easterly flow from about 1,200′ up to at least 5,000′.  But what really sticks out is the dramatic warming overhead since yesterday morning.  At 3,000′ yesterday it was around 50 degrees at 7am.  Yet at 7am today it was in the low-mid 60s at the same elevation.  Combine that with the offshore flow and we’ll see quite a jump in the temps today.  At least 8-10 degrees.  So I think it’s quite likely we hit 90 at PDX, maybe a few notches warmer in a spot or two.

Cooler weather returns Friday and beyond.  In fact the ECMWF says below normal temps Saturday through at least next Tuesday as another upper-level trough moves down into the Pacific Northwest.  You can see the below average 850mb temps (temp in celsius at 5,000′) through the 9th…pretty good agreement on that on the ensemble chart here:

tseries_850t_000-360_Portland

Check out that trough on Monday morning.  500vty_f108_bg_NA  This says SHOWERS to me just looking at the pattern only.  Yet it is early August (not June or September) so models want to keep most/all of the showers north of the Columbia River in the lowlands and in the northern half of Oregon in the mountains.  Take a look at the ECMWF rain total ending Tuesday:

ecmwf_apcptot_f156_nw

The GFS is slightly wetter with 0.10″ extending down into the Northern Willamette Valley.

Capture

The rain showing up south and east of the highlighted area is thunderstorm action east of the mountains not directly related to the cool showers coming in with the trough.  For those of you planning on camping in the northern Oregon Cascades or Washington (me) Sunday-Tuesday, it appears to be another cool and possibly showery early August period.

Chief Meteorologist Mark Nelsen