Some Weather Excitement…A Ways Away

November 7, 2011

November has been a little dull, except for a bit of Cascade snowfall, and it appears that much of the rest of this week will be dull as well.  Plenty of weather geek talk below; but the next few days (through Thursday or maybe Friday) look really nice for November.  That means little or no rain and comfortable temps.  Wednesday & Friday could even be mostly sunny.

But some interesting stuff is showing up on long range maps.   Two things to watch:

1.  Both the GFS and ECMWF (as of 00z runs Sunday evening) show a deep surface low pressure system tracking directly OVER Oregon and Washington from WNW to ESE at some point in the middle of the weekend.  When I say “deep low pressure” I mean they both show around 980 millibars.  The sudden deepening is caused by an upper level shortwave digging down over us after passing over a strengthening ridge to the west.  Of course a 980 mb low tracking from south to north along the coast or SW to NE over us is a perfect windstorm pattern.  This one isn’t a big south wind producer for us at all because of the unusual movement.  More likely a damaging northwest or northerly wind right behind it along the coast, or a damaging west wind through the Gorge and eastside.  It’s still 6 days away and only one model run has shown it, but when I see the same storm feature show up on two entirely different models, it peaks my interest.    Here is the WRF-GFS model from the UW, showing the low passing by just to our north:

2.  The ECMWF model in general has been quite cool with it’s 10 day forecast numbers the last couple of days, but now the 00z version raises the anticipation a bit more.  It brings snow levels very close to sea level at…you guessed it…the winner is…Day 10!  Yes…it’s only 240 hours away!  Sorry, had to say that since it happened lots of times last winter with the GFS.  Of course the GFS shows nothing of the sort during the same time period, so this is just pure model riding fun.  But at least it gives us something else to look at.  The first map is the ECMWF 500mb heights and deviation from normal (colored) at hour 240, the 2nd is the surface map for the same time.  Note the onshore flow, but 522 thickness over us.  Usually good for sticking snow down to at least around 1,000′.   So enjoy the model riding the next few days.  I fully expected tomorrow’s maps will be signficantly different; how so, I don’t know…Chief Meteorologist Mark Nelsen