Cold Air Still on Track

November 30, 2009

It’s like the good old days; checking out model updates for weather 5 days from now while totally missing the one day forecast.  As I suspected (but didn’t forecast), the low clouds that developed over us 24 hours ago just sat in the Valley all day.  So on the last day of November with onshore flow and no mixing of any sort, what oh what did I think would clear us out???  I don’t know.  But it did make for a great timelapse from our skycam at 1900′ in the West Hills.  It was above the cloud cover all day.

A bit of a change in the short term is strong easterly flow through the Gorge developing tomorrow afternoon and continuing through Thursday, or Friday.  This appears to be a classic chilly December east wind too.  So after a high near 50 tomorrow I think we’ll be cooler Wednesday and Thursday, with much colder nights where the wind goes calm.  Basically it’s going to get chilly, sunny, and windy for a few days.

Of great interest is the long range of course.  The usual twists and turns keep showing up in various models and model runs within the same models. 

The GENERAL pattern appears to  look like this:  We will see a shot of some sort of cold airmass this weekend and early next week.  Then we go into a much wetter pattern sometime next week as a warmer jet moves in.  My gut feeling is that it’ll be an El Nino-ish warm jet.  Of course the details are the BIG issue.  How cold?  When does it arrive?  When does moisture return?  Or is the ECMWF right (all by itself up through 12z today), showing troughing much farther offshore which doesn’t allow a blast of cold air.  For example, the 12z ECMWF showed 850 mb temps Sunday morning around -3.  The GFS at 12/18z showed -10 or so.  of There is SOME support so far for that warmer solution.  The new 00z NAM is tilting that direction.  More thoughts tomorrow, and Wednesday, and Thursday etc…

Chief Meteorologist Mark Nelsen


New ECMWF Link

November 30, 2009

I added a link to my weather page: http://www.cascadeaccess.com/~mnelsen/markswxlinks.html

About halfway down, right side, the ECMWF pulldown menu.  I put the images from the actual ECMWF site into a much easier format to look at.  That website they have is a real pain to navigate.  I’ve only got the 500mb heights working this evening, but I’ll make an 850mb/Sfc link in a day or two.