Thursday, November 20, 2014

Normal Weather Returns

The past year has brought a lot of unusual weather here in the Northwest.  Fall 2013/ early winter 2014 was extremely dry, then the deluge of mid-Feb to mid March that contributed to the tragic Oso slide.   We had one of the warmest summers/early falls on record.  Then a deluge in late October, followed by a dry, cool pattern the first half of November.  The observed (red) and normal (blue) precipitation since October 1, 2013 at Seattle Tacoma Airport (see below) illustrates our swing between extremes.

Many of these gyrations were associated with amplified upper level wave patterns with ridging associated with dry conditions and a deep east Pacific trough with wet situations.
But the next week offers something different: a typical late November upper-level pattern with a strong jet stream barreling in on the Northwest   Rain and wind in the lowlands, snow in the mountains. Nature simply couldn't help itself in the climatologically most stormy/wet period of the year here in the Northwest.

Here is the jet stream forecast (300 hPa--around 30,000 ft, lines are heights, shading is wind speed)
for Friday at 7 PM and Monday at 4 PM.

Can you see the difference?  On Monday, we had a ridge of high pressure and weak winds aloft over us, while on Friday a strong jet stream--oriented almost east-west--comes right into the southern Oregon coast.   Think of the jet stream as the conduit of storms and rain.  The hose is directed at us.

Let me show you the forecast 24-h totals of precipitation for the next 3 days.  Lots of rain as a progression of systems comes in.   And it doesn't end there.

With the jet stream core south of us, the air will be cool enough to snow at least down to 4000 ft. 

Here is the 72 h snowfall map.  Several feet in the north WA Cascades and its extension up to Whistler.   Whistler will be able to offer decent skiing I suspect.  Snoqualmie will not be able to open.

The extended forecasts suggest a major precipitation event around Tuesday and dry conditions for Thanksgiving, but we can wait on that for a future blog.

My KPLU Radio Segment

I just wanted to remind everyone that I do a weekly weather segment on KPLU radio (88.5 for many of you) at 9 AM every Friday (like tomorrow).  It is also available on their web site (   I generally give the weekend weather forecast and talk at depth on some topic.


Unknown said...


I am having trouble finding the 72hr (and beyond?)Snow fall map on the UW site. It looks like everything stops at 48-hrs. Can you point me in the right direction?


Westside guy said...

Cliff's weather segment can also be subscribed to directly from your phone. On an iPhone, just open the Podcasts app, click on the search icon (magnifying glass to the lower right), and type in "kplu weather cliff mass" (without the quotes). It'll come right up.

GaryP. said...

Since over half the fruit we eat comes from California, any updates on the long term issues with their drought would be interesting reading.

Cliff? Do you monitor the California weather?