August 30, 2020

The Lessons of Hurricane Laura for the Northwest

Hurricane Laura, one of the strongest hurricanes to hit the central Gulf coast in years, is now history, but there are important lessons for us in the Northwest.

The death toll now stands at 16.  But it is important to note that more than half the deaths were not due to storm surge or direct hurricane damage, but due to improper use of generators, leading to carbon monoxide poisoning.

Several of the other deaths were from trees falling on homes, killing those inside.

Nearly all of these storm-related deaths did not have to happen, and the lessons of Laura are important here in the Northwest, which is often hit by Pacific cyclones rivaling the hurricanes that strike the southeast U.S.

And there is something else:  Hurricane Laura was very well forecast in the days before, as is true of most of our storms.  Thus, there is time to prepare and evacuate if people would take advantage of the improving predictions.

Hurricanes Versus Northwest Winter Storms

Hurricane Laura was a category 4 storm (130-156 mph sustained winds) as it approached the Louisiana coast and rapidly declined to category 2 (96-110 mph) after landfall.  Within a half day it was no longer a hurricane.

Northwest Pacific cyclones often approach the coast with winds equivalent to category 1 hurricanes (74-95 mph) and in the case of the Columbus Day Storm of 1962, was as strong as a category 3 hurricane (111-129 mph).

Satellite imagery of Hurricane Laura and the Chanukah Eve Storm (2006) is shown below with an arrow indicating the distance of 100 miles.  Note how much larger our storms are, which means that greater areas experience strong winds.

 

 The winds of Laura gusted as high as 132 mile per hour.  Scary, particularly since serious tree damage often start when the winds get to around 40 mph. 

But what about the 192 Columbus Day Storm?   Storm expert, Dr. Wolf Read, created a map of the peak gusts for that event, and the winds were extremely similar to Laura.  Our next tier of storms, such as the 1993 Inauguration Day Storm or the 2006 Inauguration Day Storm, often produce 80-90 mph gusts.


Weather Prediction Has Become More Skillful

The track forecast (the prediction of the path of the storm) of Laura was extremely good days in advance.  I mean stunningly good.   4-5 days before, the location of landfall was predicted correctly within a few miles and few hours (see proof below).  Such small track errors within 4-5 days of landfall has become typical of hurricane predictions and represent an extraordinary accomplishment of numerical modeling and observation.  Similarly, track errors of major storms approaching the West Coast have greatly improved (decreased).


Intensity forecasts are more difficult and the skill 4-5 days out is less.  4 days before landfall, Laura was "only" predicted to have 100 mph sustained winds.  The response should not have been any different.

Lessons

1. NEVER use a generator or barbecue inside a home when the power goes out.   

As noted above, most of the deaths from Laura were from generator use inside of buildings, leading to carbon monoxide poisoning.  Here in the Northwest there have been several deaths when folks used barbecues inside homes or garages and carbon monoxide invaded homes. Never, ever do this.

2.  If strong winds are predicted, do not sleep in bedrooms that might be hit by a falling tree.

Sleep in a lower level or in part of home/apartment that is not vulnerable.  If no trees, no worries.

3.  Never drive, bicycle or walk around outside during strong winds

During almost every major windstorm in our region, someone gets killed or seriously injured while traveling outside.  The chance of any individual being hit is very, very low, but if thousands are outside, someone is going to get hurt.

Let me admit something, I almost got killed this way.  On a windy night, I bicycled home along the Burke Gilman trail and a big branch fell about 6-7 feet behind me.   That would have been the end for me if I had been a second slower.  I am very careful about this issue now.

4.  Forecasts are much better today than even ten years ago.  Take the forecasts seriously.

Combining excellent forecasts with common sense, the death tolls from major wind storms and hurricanes can decline to near zero.
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My blog on the KNKX firing and cancel culture is found here.
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6 comments:

  1. Cliff - The breadth and depth of your knowledge about numerical weather prediction is unique. I hope you will regularly update us on the status of FV3-GFS, EPIC, and other developments at NOAA, UKMet, ECMWF and other weather activities. NOAA reorganization being topic number one. Another topic being new technologies and prospects for increased forecast accuracy and range.

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  2. All good reminder words - Thanks! Here in Bow, WA it is custom to replace the string on the weather reporting rock, and also take down wind chimes, on Oct. 12. Then pretty set for the winds of winter. ..

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  3. Glad you mentioned whatI tried to mention...that 1962 storm was, according to Wolf, an outlier, unique in its formation and size, etc...I take issue with your statement that we get hit often with cyclonic storms that are as powerful as Laura was...I know we have a few heavy doses of high-wind storms, but they do not last as long as most southern hurricanes do, right?...I do remember the Inauguration Day Storm, in the early 90s..The pressure readings were very low, and the winds were very strong, but did not last as long as that "Big Blow" 1962 storm...so I think, like Wolf Read thinks, that a true "hurricane" type of storm, only hits the NW maybe once every 200 years or so...Sorry Cliff--but I really did witness something special back then..lol

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  4. I've had the same experience, Cliff, but on a completely calm day. Driving up a neighbor's driveway a rotten tree somehow decided to fall in the middle of a peaceful afternoon, it landed right in front of my car.

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  5. You might be interested in the storm in that hit Unalaska Sunday. From KTUU radio

    'A storm early Sunday morning in Unalaska recorded high gusts of 120 mph. The strong winds toppled boats, threw shipping containers into the bay and even blew the windows out of American President Lines’ crane.

    The rapidly developing storm, which moved from the North Pacific and across the Eastern Aleutians, was an intense storm for this time of year, according to climatologist Rick Thoman.

    “It appears this was the strongest storm to affect Alaska during the month of August on record,” said Thoman, who works for the Alaska Center for Climate Assessment and Policy.
    ...
    Thoman said the origin of this storm has been the topic of considerable discussion within the Alaska weather community over the past 24 hours. The storm might have been fueled by Typhoon Bavi, Thoman said, which moved into the Korean Peninsula late last week.

    “It raised eastward from north of Japan across the North Pacific, and then crossed the Aleutians near Unalaska,” he said. “The question that we’ve been discussing is was this in any way a piece of, or sparked by Bavi? It certainly wasn’t a classic typhoon turning into a big Aleutian storm, but Bavi may have supplied some energy for this storm that impacted the area.”

    Thanks

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  6. Indeed, the longer nights have all been that is needed for my lawn to already start greening up again.

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