Wednesday, December 17, 2014

A Review Of The Windstorm

Wednesday, December 17, 2014
1:46 pm

Last Thursday night, right after I had finished my final, my mom and I decided to trek up to Sandy Hook, which is a little coastal community situated on Cultus Bay on the southern tip of Whidbey Island, to catch what ended up being the biggest windstorm of the year thus far for the Pacific Northwest as a whole, and some of the strongest winds I have experienced in my entire life. Here, I'll just give a general overview of the storm, and I'll show you some pictures and videos that I took up at Sandy Hook Thursday night and Friday morning.

First off, let's take a look at an animation of the windstorm. The loop below shows water vapor satellite imagery from November 29th to December 14th. Our windstorm begins forming to our southwest at about 0:21 and passes over our area at around 0:24.

Here's a more in-depth picture when it was near peak strength. Look at the beautiful, symmetrical form of the cyclone, and how tightly the bent-back-occlusion wraps around the center of circulation. It almost looks like a hurricane. Pretty extraordinary.

8 pm December 10, 2014 (PST). Retrieved from NOAA WRH Satellite Loop.

As I explained in my previous post, this cyclone was a "Sou'wester." Most of our major regionwide windstorms have been of the "Sou'wester" type. The Hanukkah Eve Storm was the most destructive storm for Puget Sound since the great Columbus Day Storm of 1962, but it was not a truly region-wide storm. This storm affected everywhere from San Francisco (they actually closed schools due to the wind and rain from this storm... wimps) to Vancouver Island and Southern British Columbia. Seattle did not experience anywhere near the amount of damage it experienced with the Hanukkah Eve Storm, but if this storm had kept its strength as it tracked northward and if it had tracked a bit further east through the Chehalis Gap, the winds could have approached Hanukkah Eve levels.

One of the most striking things about this storm is how closely its track mirrored that of the Columbus Day Storm. Take a look at this picture below comparing it to other famous Sou'westers to strike the Pacific Northwest. You can see that its central pressure is much higher, hence the lower winds over much of the area. However, it tracked much more closely to the coast, and if it had deepened to 960 millibars or lower, there is a distinct possibility that it could have caused the tremendous winds witnessed in 1962.

Credit: NOAA

I wasn't able to find a definitive list of the highest gusts throughout the entire Pacific Northwest region, but I was able to find some gust information for some individual areas. I put a small list together of gusts that I thought that were particularly notable. Values given are in mph. I have a more complete list of gusts below from the Seattle, Portland, and Pendleton NWS forecast offices. I looked but I could not find any reports from California NWS offices

NWS Portland gusts
NWS Seattle gusts
NWS Pendleton gusts


White Mountain: 139
Mount Lincoln: 135
Slide Mountain: 112
Mammoth Summit (yes, the ski area): 111
Alpine Meadows: 109

San Francisco: 50
Oakland: 46


Mt. Hebo (3160 ft): 90
Sea Lion Caves: 89
Marys Peak (4137 ft): 88
Newport (120 ft): 72
Portland (30 ft): 67
Garibaldi: 64
Salem: 53


Crystal Mountain (6870): 97
Mission Ridge: 78
Mt. Baker (5000 ft): 78
Naselle Ridge (2008 ft): 77
Port Townsend (28 ft): 70
Whidbey Island Naval Air Station (47 ft): 69
Hood Canal Bridge : 63
Cape Disappointment: 63
Paine Field (Everett): 62
Useless Bay: 59 (this is the closest location to where I was)
Hoquiam (12 ft): 56
520 Floating Bridge: 51
Boeing Field: 49
Sea-Tac (370 ft): 49
Tacoma Narrows Airport: 48

As you can see, the highest winds generally occurred on mountain ridgetops. I heard rumors of Mt. Hebo having a 130 mph gust, but this figure did not show up in the official NWS list. Portland's gust of 67 mph was actually the strongest gust since the great Sou'wester of December 12, 1995, so this storm was no slouch.

Also, just for funsies, let's take a look at all the rain that fell in California. While Seattle and Oregon weren't extraordinarily wet, California, particularly San Francisco and areas north, got absolutely soaked. This storm was fantastic for drought relief, but it would take 4-5 more of these to end what is the worst drought for California in at least 1,200 years.

Going back to our region, some of the highest winds in all of Western Washington were located right where I was. Useless Bay is that larger Bay that is to the west of Scatchet Head on the southern tip of Whidbey Island. This lines up well with what the UW's WRF-GFS model was predicting at the time; note how the highest winds are there and regions to the south over the water.

Valid 10:00 pm PST, Thu 11 Dec 2014 - 18hr Fcst

Anyway, let's take a somber look at some of the catastrophic damage inflicted upon the residents of Sandy Hook.

Play structures were ripped to shreds...

Furniture across our backyard was slaughtered...

And I would have loved to witness the gust that put this chair in this precarious position.

But all dishevelment of lawn furniture and children's play structures aside, there was some moderate property damage as well. Our "crab shack" got slightly de-roofed, which may end up being a blessing in disguise, as we now have an excuse to give it a new one. I didn't take a picture of it, but our 18-20 foot aluminum canoe got blown right off our dock and drifted a good quarter-of-a-mile down the man-made canal that our dock lies on. We are very lucky to have found it!

A big wooden fence that surrounded the community swimming pool toppled over under the storm's strong gusts.

Also, some similar fences right off the bay slightly leaned over due to the strong winds coming off the Sound. All in all, the structural damage doesn't look like much, but after witnessing how strong the winds were and how they hardly caused any damage, I've really gained an appreciation for the extreme strength of winds when significant structural damage is evident.

When we drove out to go back to Seattle, there were tons of branches all over the road and many downed trees that had taken out power lines. Our power was out for two days.

Lastly, here's something that's unrelated to the winds but is related to the low pressure system itself. With such low pressure over us in tandem with astronomically high tides, the observed tide was as high as I had ever seen it and almost passed over our dock. Pretty incredible.

On a final note, I'll leave you with some videos that I took. Here's one that shows how noisy our house was on that night, with some tasteful lighting to boot.

And here's the piece de resistance... an on-site video of the storm itself. I was recording right above a breakwall on the coast that was actually very close to the children's play structure that got thrown around. I'd estimate that winds were a good 50-55 on the water at that time, but as they went over the breakwall they accelerated as the wind was noticeably stronger there than right on the water.

I'll have more blogs coming soon, including ones regarding the potential for cold in the extended future. However, the short term forecast holds flooding, primarily for Oregon, where over 15 inches of rain may fall in select locations over the weekend.


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