The Cold Blast is Here

December 6, 2009

Just a quick post tonight, since I’m not actually working.  It is COLD out there tonight when you add in the wind!

As I mentioned on the previous post, I was at the Coast from midday Saturday to around 2pm today.  It was probably good to be gone and miss the hourly updates of falling (or steady) temps and dropping dewpoints.  Whatever there was of an arctic front it clearly passed through late last night or early this morning on the way south into California.  This wasn’t the type we sometimes think of.  Often it’s moist, we are in a maritime airmass, and then it’s a dramatic switch to easterly wind and lowering dewpoints with clearing skies.  This time we already had dry and chilly air coming down from the north, but then the much stronger cold advection kicked in early this morning.  It takes a cold airmass to have temps hold steady all day and not even rise with full sunshine plus downsloping wind.  If you were disappointed that temps didn’t fall like previous outbreaks of arctic air, consider this:  With dewpoints in the single digits and temps in the low-mid 30s today, imagine if precipitation would have started falling (like January 2004 and last December).  The evaporational cooling would have kicked us down into the 20s by afternoon easily as the dry air continued pouring in.

You may have noticed we had a wind coming right over the Cascades today, with not so much coming through the Gorge.  That probably helped hold temps up a bit too.  In fact Corbett at the west end of the Gorge was one of the calmer spots.  Most of the strongest gusts were west of I-205.  And the true test of downslope wind was a 40 mph gust I had at my home…only the 2nd time in 5 years where I’ve actually seen a gusty wind come from the east off Larch Mountain.  My “gorge wind”, normally curls around the hill and comes in from the northwest.  Speaking of that, I don’t expect a raging gorge wind the next few days.  That happened in the 1998 cold spell.  Gusts in the Gorge remained below 60 mph then.  Maybe just 5-8 millibars max tomorrow and then it dies down Tuesday/Wednesday a bit.  More Thursday through Saturday as another dome of high pressure slides south plus a low approaches from the southwest. 

So temps are slowly but steadily cooling tonight; but I’m encouraged by the cold air to the north and east.  It’ll continue filtering in for the next 24 hours, so we sure haven’t reached the “coldest airmass” point yet at the surface.  Check out Spokane…11 degrees with a raging northeast wind.  That’s about the coldest you see over there with the wind blowing.  That’s not a cold, calm, and clear nighttime temp but a frigid airmass surging south.

I looked at all the maps through next weekend.  Looks like ECMWF and GFS might, just MIGHT be converging on the return of moisture for next weekend.  As early as Friday night, but it’ll be dry at least until that time.  Not much modification of the low level airmass, so it’ll stay cold through the end of the week.  Stay warm!

Chief Meteorologist Mark Nelsen


A Dusty Gift Today

December 6, 2009

I just now got back into town from emceeing the Seaside Providence Festival of Trees.  Crystal clear skies and blowing sand at the beach, really chilly!  Then nice until we got down towards North Plains.  It progressively got dustier and dustier looking until Troutdale where you could hardly see 10 miles to Larch Mtn.   Then I remembered how the models showed strong northeast wind across eastern Washington.  Looks like the very dry air and wind has brought dust right over the Cascades and through the Gorge.

I’ve looked at NOTHING else, so I’ll post my thoughts about the upcoming weather later this evening when I get a chance.

Chief Meteorologist Mark Nelsen