Thursday, November 27, 2014

Northwest Residents Travel from Hawaii to the Arctic Without Going to the Airport

In one day, Northwest residents will go from breathing air that been over Hawaii and vicinity to air that has passed over the Canadian Arctic, and will do so without having to move an inch.  Hawaii and the Arctic will come to them. Far better than a Rick Steves travel  video...you will be breathing the real thing!

Today, I was working outside after putting a turkey in the oven...it was TROPICAL outside, with humid air approaching 60F.  Many local reporting stations exceeded 60F, with some in the Tri-cities hitting 70F.  It was 73F in Honolulu at 3 PM.


The tropical air came in on Tuesday with an amazing warm front.  Here is a trace of the wind speed, wind direction, temperature, and dew point temperature that day.  Around 01Z (about 5 PM), the temperature increased about 8F in an hour, the winds shifted to the south, and wind speed increased rapidly.  A magnificent warm front--a rarity here in the NW.


We can see exactly where the air over Seattle has been coming from using the NOAA Hysplit model.  Here is a trajectory (the path of the air) ending over Seattle at 4 AM Thursday for a period of 96 hour.  Started a bit northeast of Hawaii.

And the atmospheric moisture for 10 PM Wed. night shows a plume of subtropical/tropical moisture heading right for us.  This is known as an atmospheric river...and in this case the Pineapple Express.

So you have been breathing moist, warm Hawaiian air if you have been living in the Pacific Northwest the last few days.  No need for jet travel.

But everything will change radically on Friday.  The Arctic is coming...to YOU.


 Early Friday afternoon a strong cold front...in this case an ARCTIC FRONT...will be moving into western Washington.  Here is the latest WRF model prediction valid at 8 AM Friday:  big temperature drop behind it, although the coldest air (purple and brown) is still in British Columbia.


The front will move southward during the day and by Saturday at 4 AM, we will have modified Arctic air entering the region (see graphic).

 And by 4 AM Sunday, the cold air has flooded Washington State and Montana, and pushing south into Oregon.

 As the front moves though, we will switch from southerly to northerly winds and the trajectories will change with them. Here is is trajectory for air ending at 1000 meters above Seattle on Saturday morning at 4 AM.   Started in the Yukon!  Then moved to the coast before heading over Seattle


And what about snow?  Right now if looks like the temperatures will be too warm for snow in the lowlands of western Washington on Friday, but there will be plenty of precipitation in terms of rain.

Here is the 24h snowfall ending 4 PM Friday.  Lots in the mountains but nothing near sea level.
On Friday night and Saturday it will be cold enough to snow, but precipitation will be sparse....thus only very light snow west of the Cascade crest, with the NE Olympic Peninsula being favored, as will a band north of Seattle in a Puget Sound Convergence Zone.  If the upper level trough approaching on Saturday is displaced farther to the SW, there could be much more snow....so keep in mind there is some uncertainty with this forecast.

Temperatures will plummet over the weekend, with highs in the 30s.  Here are the forecasts from the National Weather Service and the Weather Channel....both pretty similar.



9 comments:

The Drennans said...

Been loving the mild weather. And won't mind a little snow either.

JordanP said...

The temperature dropped 10 degrees here in Fauntleroy between 0900 and 0930. It has dropped another 10F since then (now 1530) and the harder rains showers seem to be driving the temperatures even lower. I don't know when it will change over to snow, but at this rate it may be before to late tonight.

Unknown said...

It actually snowed (huge clumpy flakes) for a few minutes in Redmond Ridge this afternoon!

clive boulton said...

Snow in the cascades just in time to stem the pineapple express flowing back to the pacific down the Skagit River.

TJ in Kingston said...

Nice waking up to a couple inches of big fluffy flakes in Kingston.

Pete Madsen said...

It is snowing a bit here just uphill from SR16 at Olalla, but the temperature is mid-30's and the driveway is black. Our fingers are crossed that the weather won't hurt the Winterfest craft show at Peninsula High School that we're doing today. After the warm weather we've had it will take a while to cool the ground to the point that the snow would present travel problems.

2otaku said...

I don't get the power going out without even a wind advisory over in Poulsbo. Mine was out 2 hours and the PSE outage map is still showing new problems over here at noon. 2 inches snow at my place.

Michael said...

Reached a low of 19.76 degrees on Orcas NW Mt Constitution at 8:24 am this morning......

TJ in Kingston said...

It must be heavy snow packed into our two inches. We've had trees down and power flickering all day.