Tuesday, December 1, 2009


Does this remind you a bit of December past?
Cold, but no snow? Bah! Humbug!

I just viewed the latest forecast output (computer models initialized at 4 PM) and also the uncertainty (ensemble) forecasts from NCEP (the National Weather Service forecasting center) and ECMWF (the European Center for Medium Range Forecasting). The die is cast for the next 5-6 days: dry and cool, and getting COLD.

With clear skies, temperatures have already fallen into the 30s in much of the areas, some colder spots are already below freezing. Tomorrow will be like today...perhaps with some fog in low spots in the morning. With an increasing offshore pressure gradient and easterly winds aloft, the fog probably will not be extensive or long-lived. Sun tomorrow. No precipitation at all. Ditto Thursday. Friday a weak disturbance will pass to our north...all we will get is some clouds...particularly the northern portion of the State.

Saturday again cool and dry with sun. Sunday will be interesting as a strong surge of cool air pushes into the region with strong easterly flow in the lower atmosphere. Winds will howl through the Fraser River Gap and flags will be flying in Bellinghan. Strong easterlies in the Strait of Juan de Fuca. But it looks dry.

Monday and Tuesday could be the coldest we have seen in a long time...particularly in sheltered spots. My advice...you have delicate plants--cover them with mulch, bags, or whatever you do. Or bring them inside. This is potentially plant killer weather--but we will know more in a few days.

Some of the forecast models keep it cool virtually all next week, others have different solutions...but no need to worry about that--I am more than content to forecast 5-6 days out.

Special Lecture: I will be giving a noon-time weather lecture ("Is Rainfall Getting More Extreme?") and a book signing at Elliot Bay Books, December 2 at 12 PM. Downtown in Pioneer Square

KIRO TV WEATHER SPECIAL: Wednesday, Dec 2 at 7 PM. For more info check out: http://www.kirotv.com/station/21774954/detail.html


Anonymous said...

When you say coldest we've seen in a long time is that the past year long time or past 10 years long time?

Thanks for the great forecasts and education on NW weather.

Craig said...

yes I am curious if when you say cold... How cold and how long since we have had this type of cold. Last December was impressive. I have been watching the models and some or wrapping up some moisture into the arctic front for early next week. I know it is early but I have to admit it has my attention. :)

Big White Ball said...

Cold, clear: the beauty of the northwestern mountains and waters is set in stunning relief this week. And I don't recall seeing a full moon so bright in years. Made my coffee by moonlight this morning. Last night people were out walking and jogging in moonlight. Quite a sight!

mainstreeter said...

It was definitely a killing frost. I've noticed some of the trees still have leaves on for this time of year.

Must read blogs said...

lots of thick frost here in chehalis! I have to go get mittens and hats for the kids, especially the 15yo who gets to march in the santa parade here on saturday.

mainstreeter said...

NWS in Portland is forecasting a chance of snow in SW Wash south of Longview and NW oregon over the weekend starting Friday night. It always does this during the steam train events in Portland. The tv station websites are not talking about much of a chance.
It is supposed to remain cold through the middle of next week,

HarrisonCZ7 said...

This link shows how cold:


It's definately chilly in Spokane.

31F now, 19F last night.

Joseph Ratliff said...

Nothing earth shattering cold...last year it was colder during the "cold snap"...but looks to get into the low-mid 20's for low temps from Sun-Tues or so.

Maybe time to start watching the pipes eh? :)

mainstreeter said...

For all the amateur radio Skywarn spotters out there, this Friday and Saturday is for you


Date & Time:
1600-2000H Friday, December 4, 2009
0800-1600H Saturday, December 5, 2009
SKYWARN Recognition Day 2009
K7MMI Repeater System: http://www.k7mmi.net
147.20 + pl 118.8 (Everett North)(Standalone)
146.98 - pl 107.2 (Seattle-Tacoma) (Linked)
147.20 + pl 127.3 (Olympia South including south coast)( Linked)

Call sign, signal report, QTH, and a one or two word description of the weather occurring at your site ("sunny", "partly cloudy", “cloudy”, “rain”, "windy", etc.)
Earn a SKYWARN Recognition Day certificate by working just one National Weather Service office. Submit a list of the NWS stations you worked with a self-addressed stamped envelope to:
SKYWARN Recognition Day
920 Armory Road
Goodland, KS 67735

Cliff Mass Weather Blog said...
This comment has been removed by the author.
Must read blogs said...

red skies in the morning sailors take warning here in chehalis.

Anonymous said...

Got fooled again by the photo that this was a new posting. Wish you'd post more often, Cliff, but we know you are busy.

Our 3rd freeze in a row in Bellingham with a low of 27F. Pansies and Calendula are hanging in there. The nasturtiums that resprouted over the warm spell are history.

RobbyRob said...

Cliff, Can you explain the difference in setup between the cold snap we are about to experience and the snows of last december. I am guessing the moisture last december came down from alaksa and was colder and didn't cause a switch over to rain. Thanks!

Charlie Phillips said...

RobbyRob - The moisture for the really big snowstorm last year actually came directly off the Pacific; we just had really really cold air already in place. It was this really cold air that came from the arctic. While most arctic air is significantly modified before it comes here, this air was less so, and by the time the moisture got here, temperatures were in the low to mid 20s and stayed there for the majority of the duration of the storm (even as temperatures warmed aloft and caused some freezing rain)