Wake Up…It’s Cold Outside!

August 24, 2012

Whew, I bet it feels like Fall out there this morning once you step outside.  Temperature across the entire Portland/Vancouver Metro are in the 40s!  Even PDX has made it down to at least 50 degrees.  Your tomatoes aren’t going to like it.  We had dry air, clear skies, and now the increasingly long night hours as we head towards September.  The three added up to our coldest night for most areas since mid June.  Fall can’t be far away, and the weather maps continue to look like Fall.

The cooler than average weather is going to continue, with one summery day on Saturday thrown into the mix.

Today we’ll see plenty of sunshine since the low clouds appear to be a bit scattered and they are moving more north to south versus onshore from west to east.  But with the chilly start we’ll only be in the 70s this afternoon.

Tomorrow we get nice offshore flow, which shows up well on the WRF-GFS 12km cross-section:

See the wind barbs at 12z on 25th (5am Saturday) are easterly from about 1,000′ up to 4,000′ or so.  It’s still summer, so that allows our temperature to jump well into the 80s.  Sunday should be okay too, although it’s been a question mark since the ECMWF has been shoving an upper-level trough closer to us a bit more quickly.  No other model has been doing so.  If we get lucky then, one more nice day Sunday, just significantly cooler with no offshore flow.

Alright, then we’re going to continue with cooler than normal temps again because upper-level troughing will linger through the foreseeable future.  Heres the ensemble forecast of 500mb heights from the GFS from last night’s 00z run:

then next Wednesday, the 29th with the ECMFW ensembles:

then 10 days out, Sunday of Labor Day weekend, the trough is still there!

The main message?  We have returned to the weather pattern we saw the first half of the summer; cooler and cloudier than normal.  So what about rain?  An upper level trough or a series of them nearby should give us rain at some point in late August.  Models have been slow to push any rain into here.  The GFS has been hinting at some light shower either Monday or Wednesday.  The ECMWF points to later Tuesday or Wednesday.  We’ll see.

By the way, I’m headed home today after a good 3 day weather conference in Boston.  Last night was fun at Fenway Park…perfect weather.  Learned lots about the weather and broadcasting world…I’ll do a posting on that next week.  Enjoy the weekend!

Chief Meteorologist Mark Nelsen