Cooldown Begins

September 7, 2006

Finally, a bit cooler today.  After 3 days in the mid 80’s, the metro area cooled down into the upper 70’s and lower 80’s today.  Onshore gradients are not much stronger this afternoon, but I expect a reinforcing push of marine air tonight to give us a longer period of morning clouds tomorrow.

Then a very weak front moves through tomorrow night & Saturday morning.  Models have anywhere from a closed low moving right through the middle of Oregon to an open trough swinging north through Washington with this system.  Either way I think we’ll see at least measurable rain Saturday morning.  NAM and GFS at 12z both give us .05 to .10" total at PDX.

It’s a one shot deal though as ridging builds in quickly behind it for next week.

Several of you have pointed out the big trough on some maps for next weekend.  Watch out!  Its the same pattern that fools us all winter long in the GFS.  It shows a ridge retrograding and a deep trough dropping cool air south out of Canada.  Then the next run puts the ridge closer to us.  Sound familiar???  Wasn’t there always a "big cold spell" right around the corner on the GFS last winter?  So I’m ignoring that for now and keeping temperatures in the 80’s through at least Thursday, assuming the ridge will stay closer to us than models show…Mark