A Crazy Weather Night

November 17, 2010

Apparently we’ll need to get used to this in a La Nina winter?

Just as the heaviest rain seemd to be backing off, the snow level began dropping, as expected.  But then it just kept dropping on the east side of town up against the Cascade Foothills.  There is now snow on the ground well below 1.000′ in those areas.  Yet above 1,500′ in the Coast Range there is nothing.  Clearly cold air damming up against the west slopes of the Cascades.  I remember it happening in November 2003, and Halloween 1994.  That was the night several inches were dumped on Sandy, lots of trees fell on Highway 26, and a few power outages too.

I made a big change to the 7 Day forecast…a bit gutsy (we’ll see if it was a dumb move or model riding).

I feel there is a significant trend now in the “shorter range” of 3.5-5 days out, instead of 7-9 days out.  When it’s that close and models are getting into line (in this case pointing to warmer), I want to change the forecast instead of waiting for “just one more run”.  I had the snow/rain mix for Monday in there all the way until 9pm, then pulled the plug after seeing the 00z GFS and 00z ECMWF come in with almost exactly the same result.  The shortwave that was forecast to dig down right over us Monday/Tuesday (depending on the model) instead heads much farther east.  That does two things:  keeps us dry after Saturday, and takes the main cold air east.  So now can I reinstate that #2 and #3 from two posts back?  That’s not waffling is it?

There is also a hint of low level onshore flow returning Tuesday/Wednesday.  Both the ECMWF and GFS show moisture returning with the onshore flow…a bit strange, but I though we had something like that during Christmas Break two years ago.  The pattern looked familiar to me.

Okay, it’s midnight and I’m headed home to measure the snow.

* A side note:  Today was the most active day on this blog since the beginning of the big blast last December…27,000 views today! The year to year numbers are up a good 30%.

 

Chief Meteorologist Mark Nelsen