Very Intense Low near Pacific Northwest

[Marc Austin]

I hadn't seen anyone post anything on the strange intense low pressure system that developed off the coast of Washington/Oregon. For a brief time it had the appearance of a hurricane. There was a clearly defined "eye" and "eyewall" and an intense ring of convection surrounding the "eye". I know it's not unheard of to have such a storm, but it seems very unusual. SST's are apparently 2C higher than normal in the area the storm developed. Just thought it would be worth mentioning and that it might start some discussion. Here's a pic of the storm at it's strongest point and a link to wunderground where I found the information on it:

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=569&tstamp=200611

 

[B Ozanne]

Looks a lot like a "Polar Low." Something we learned about in school, but I vaguely remember. Mainly because polar lows are not part of my everyday life.

I found some more information here: http://en.wikipedia.org/wiki/Polar_low

 

[Jim Southard]

Wow... what an unusual little storm! I think about the only thing that can be said with certainty about it is that it's a mutt. The satellite image that Marc put up earlier shows the best of its warm core characteristics... tight spiral form, eyelike feature, convective banding. You can also see some of the features nearby that argue for extratropical/cold core, like the decaying occluded front northeast of the low and the new wave developing on the cold front approaching the west coast.

I want to call this a polar low, since it's in the cold air poleward of the polar front and the convection was pretty shallow. I don't think I've ever seen such a nice spiral form polar low in the Pacific so far to the south though. From what I've been able to tell so far (and someone please correct me if I'm wrong), the 500 mb heights and temps aren't particularly low/cold in the area, which makes for a non-ideal environment for a polar low to develop... but SSTs are unusually warm in that part of the Pacific so maybe the thermodynamics were good enough.

Either way (polar low, hybrid, subtropical), it's a really neat storm and a great discussion item. There are parallels between it and the South Atlantic cyclone in 2004 (see the UW-CIMSS archive of images and other goodies), and some of the spiral form polar lows that occur in higher latitudes.

BTW, the Navy is maintaining info on this system on their tropical cyclones page (at least for a little while longer), as "Invest 91C".

I wonder if any ships or buoys passed close enough to the center to get a good read on the pressure? I saw estimates around 990 mb or so earlier today with gale force winds... but it would be nice to get an actual ob.

Oh, and before I forget, it's good to be back on ST.

 

[B Ozanne]

It certainly is small. You could squeeze the storm into 1/4 of Oregon.

 

[Billy Griffin]

Looks like we're in for some obvious flooding, but many locals are fearing the unknown now that we have all this new "urban sprawl" in the low-lying river valleys.

Seattle NWSFO discussion:

THE SCREAMING MESSAGE IS THAT THIS SITUATION APPEARS TO BE SHAPING UP INTO A MAJOR FLOOD EVENT. IF THE MODEL PREDICTED RAINFALL AMOUNTS FOR THIS EVENT VERIFY...IT WOULD RIVAL THE SEVERE FLOOD EVENT THAT TOOK PLACE BACK IN NOVEMBER 1990.

The Carbon and Puyallup Rivers run parallel along the city limits of Orting (where I now reside) and the entire river valley here. These are the same rivers which originate high up near Mt. Rainier and are the ones feared most if a lahar were to occur.

The rivers are already up and continue rising rapidly. I'll try to grab some photos today, as it appears there is a lull in activity before this monster storm moves in later today through Tuesday.

Who knows, my house could get relocated to Puget Sound by the time this one's over.

 

[Bob Schafer]

This is the MODIS image of the day for today.

http://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2006-11-05