Hot & Smoky Weekend Ahead & Much Warmer 7 Day Forecast

August 21, 2015

6pm Friday…

The lack of fire smoke west of the Cascades has been nice the past two days, but it’ll be back this weekend.  Take a look at the latest U.S. Forest Service BlueSky smoke dispersion model:

http://viewer.smoke.airfire.org/run/standard/PNW-4km/2015082100

A couple of still images show smoke from big fires in northern Washington and the Cougar Creek fire on Mt. Adams heading to the east-southeast right now:

dispersion_6pmSat

Then as our wind switches to northeast and easterly the next 24 hours the smoke is carried right into Western Oregon and SW Washington during the day Saturday.

dispersion_3pmSat

That smoke will be pushed back out of our area again late Sunday and Monday as the flow turns weakly onshore again so at that point haze should diminish again.

So how warm will it get this weekend?  It’s obvious we have a pretty decent easterly wind flow through the Gorge tomorrow…maybe 3 millibars.  You can see the solid offshore flow during the daylight hours Saturday on the 4km WRF-GFS cross-section.  Note time goes from right to left.  This morning is on the far right side, Monday afternoon on the far left side:

kpdx.th

Winds will probably be gusting around 40-45 mph at the Vista House wind gauge tomorrow morning-midday.  Gusts 15-25 mph on the east side of the metro area midday as well.  850mb temps climb to around +18 or +19, which according to my chart means a high temp 90-95 degrees.  I figure we need to knock off a couple degrees for loss of sunlight due to the smoke, so I have gone with a high temp of 92 at PDX.  Sunday maybe just a notch or two cooler, but still we probably will add 1 or 2 more days to the 90+ count for this year when the weekend is finished.

The big change to the forecast is for next week.  Models are definitely struggling with what’s going on in the Pacific, and the Ridiculously Resilient Ridge.  They HAD been advertising a cool trough coming down and hanging around for an extended visit along the West Coast.  But in the past 24 hours they have steadily been pushing the low farther and farther offshore with each run.   The 18z GFS has now gone as far as suggesting we stay very warm with maybe another 90 or two returning the latter part of next week!  Take a look at NEXT Saturday, the 29th from last night’s GFS run vs. the latest.  See the difference?

saturday_29th00z

saturday_29th18z

The unprecedented dry weather will continue; we’ve only seen .12″ rain so far this month.  I am starting to see young trees dying (fir trees turning brown) on the sides of the freeways on my daily commute…water your trees!

Chief Meteorologist Mark Nelsen