How Much (Tornado) Warning is Enough?

In recent years, the emphasis in meteorology has been to gain “lead time” for tornado warnings (i.e., issue the warnings sooner relative to the storm’s arrival time). The U.S. average now is around 14 minutes. In the devastating Alabama tornadoes on April 27th, the average lead time was 24 minutes. In Joplin, the lead time was 19 minutes.

It is an important question because there will always be a tradeoff between accuracy and lead time, i.e., tornado warnings with one hour of lead time (given today’s science) will be inaccurate most of the time whereas 1 minute lead time (see below) will be extremely accurate.

AccuWeather decided to ask, via its Facebook page, how much “lead time” readers wanted. Here are the results:

While this represents an unscientific poll of about 800 people (voting still going on at the link above), it does suggest that 14 minutes is adequate.

I believe that the bigger problem is false alarms and would rather see meteorology focus on that issue rather than extending lead time further.

More on Selective Tornado Siren Activation

Here an article I’d like you to read. The money quote:

Nick Crossley, director of emergency management and homeland security for Johnson County, said the warnings on Saturday night were necessary throughout the entire county.
“We erred on the side of caution,” Crossley said. “It’s much better to sound the sirens and warn people than not to sound the sirens.”

A personal note: I’ve met Nick and he is a dedicated public servant who wants to do the right thing. But, in this case, was sounding the sirens the right thing?

Here is the radar with the National Weather Service’s tornado warning plotted in red. You’ll notice only a small part (southwest) of Johnson Co. was in the tornado warning.

Sounding the sirens in Edgerton, Gardner, and Spring Hill was appropriate. I’d also say to sound them in Olathe because they are right on the edge of the warning. But the rest of the county?  No. It was a false alarm — the tornado dissipated before it reached Johnson Co.

Earlier in the evening, the sirens went off in Lawrence even thought it was never in a tornado warning (see below):

I’m sure that emergency manager thought he or she was doing the right thing and erring on the side of safety, as well.

Here’s the problem: We are training people to ignore the sirens because of all of these false activations.


The National Weather Service builds a “margin of safety” into the (relatively new, since 2005) “path-based” warnings. The emergency manager (who is not a meteorologist) building an additional margin of safety over and above the NWS’s leads to far too many siren activations.

When the sirens were pressed into tornado warning service in the 1950′s and 60′s, the “countywide” and “err on the side of safety” philosophy made sense because meteorology was not very good at tornado warnings.

Now, meteorologists can actually predict the path of tornadoes. I believe it is time for selective siren activation to become the norm.

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Sectorize the Sirens, Please

A tornadic thunderstorm passed across Topeka this evening bringing considerable hail and a small amount of wind damage. The tornado touched down northeast of the city.

Funnel cloud over Topeka. Photo by Taylor Buckley.

Large hail in Topeka.  Photo by Taylor Buckley.
The National Weather Service did a good job of warning on this storm. Here is the radar of the storm along with the red polygon outlining the tornado warning:

Now, look at the lower right-hand side of the photo. Lawrence is clearly outside of the tornado warning polygon. Yet, the tornado sirens in Lawrence were blaring with people going about their business.  Why? Because the tornado warning clipped the northwest edge of Douglas Co. and, like most jurisdictions with sirens, they are sounded on an “all or nothing basis.”

Sky in downtown Lawrence minutes before the sirens were sounded.

The “all or nothing” approach was reasonable in the ’50s and ’60s in the early stages of the tornado warning program because we genuinely were that imprecise in our warnings (i.e., warning entire counties and cities).

But now, meteorology can provide accurate warning of the path of tornadoes, as we did this evening. It is past time to start selectively activating sirens. Give us a call at AccuWeather at (316) 266-8000 and ask for sales. Our SelectWarn® system will solve this problem.

Otherwise, we train people not to pay attention to tornado warnings and that is a dangerous lesson to learn.

P.S. My son-in-law Bill Cross graduated law school which is why we were in Lawrence today. Congratulations, Bill!!

ADDITION: Spectacular photo of the tornado near Lake Perry here.

BUMPED due to tornado coverage as this is an important issue.

A Comment Worth Sharing

This was posted in the comments attached to my posting about last week’s Vilonia, Arkansas, tornado.

Teriann Shrum said…
The pinpoint warning of this horrific storm and it’s 40 minute gateway for warning viewers of it’s arrival is what saved our lives. The image as shown is the Black Oak Ranch Estates community that is 5 miles southwest of Vilonia. Accurate pinpointing of this storm gave us time to seek shelter from it and survive. Out of 120 homes, 16 still stand. We lost 4 members of our community and it could have been many more. THANK YOU for the excellent coverage received from KTHV’s Chief Meteorologist Ed Buckner that saved our lives and the lives of my family! The devastation was “pure hell” for all of us.

Teriann was doing one of the things I hoped would happen when I wrote Warnings: That meteorologists would start to get some of the credit for their lifesaving work. So, way to go Ed!

I also want to mention the incredible work by James Spann in Birmingham during last week’s historic tornado outbreak and the one ten days before.

And, it is not just the TV meteorologists, it is the entire profession that built the technology and discovered the underlying science. Teriann had seen this posting — done the night of the tornado — that showed the tornado before it got to Vilonia. The tornado was moving northeast at 60 mph — a mile a minute — but because of Doppler this non-standard tornado had excellent warning.

Click to enlarge radar images.

Debris ball (left) and Doppler couplet (right) of the violent tornado before it reached Vilonia (circled, at left).

Without this technology and dedication of these meteorologists, the death toll in April would have been in the thousands.

North Carolina Update

Yesterday, my assistant sent out the following press release to journalists across North Carolina. It is my goal to help educate the public in how the weather warnings system will save many lives and protect property. The media is a very important part of this warning system. As I mentioned in an earlier post, I will be in North Carolina this week to present on extreme weather. I always will be available to any of the media to share information on the up to date extreme weather warnings systems. I truly believe that by sharing information and creating partnerships with the media sources that many lives will be saved during extreme weather incidents.

FOR IMMEDIATE RELEASE:

CONTACT: Mike Smith
Mike Smith Enterprises
(316)204-9969
www.mikesmithenterprises.com
http://meteorologicalmusings.blogspot.com

Tornadoes are NOT unpredictable! Extreme Weather Expert, Mike Smith presents on Tornado warnings in North Carolina

Charlotte, NC April 18, 2011 – In the wake of the killer tornadoes that hit the Carolinas this week, Mike Smith, award-winning meteorologist will be presenting cutting-edge information on accurate tornado forecasting. Mr. Smith’s presentation focuses on saving lives and will dispel last week’s national news story that tornadoes are too unpredictable to accurately forecast.

“We are getting to the point in America that the issue is not so much whether there will be an advance warning but making sure that everyone who needs to receive the warning gets it.” states Mike Smith concerning why the North Carolina Tornadoes resulted in fatalities. Mr. Smith is currently developing a national safety agenda to ensure that all cities and especially rural areas have access to up-to-date weather warning systems.

On April 21, 2011, Mr. Smith will be presenting information to the Risk and Insurance Management Society in Charlotte. Mr. Smith will be covering both tornado and hurricane warnings and how to save property and lives in the event of extreme weather. Mr. Smith is the recipient of the highest awards in meteorology, holds 15 patents and has authored the book “Warnings” the true story of how meteorology has saved lives.

For more information, contact:
Mike Smith Enterprises
Mike Smith, President
e-mail: speeches@mac.com
phone: (316) 204-9969

- END –

North Carolina journalists, please let me know how I can help you to help your readers.

Last Update of the Evening

I’m signing off for the night. Here are some thoughts that might be useful…

The full extent of the damage and injuries with the Iowa tornadoes is unknown at this time and likely till not be known until mid- to late Sunday morning.  There is a map of the tornadoes’ path in the posting below.

Here is the map of the greatest risk area I posted at 9:16am that encompassed northwest Iowa.

The tornado watch was out well in advance of the storms (scroll down). We define “significant” tornadoes as those of F-2 intensity or greater. There is a tool that helps us forecast where strong tornadoes may occur and it signaled that northwest Iowa was at risk (we look for values of more than 1, these were 6+). Storm chasers used this information to get into position to report on the storms and, when damage occurred, to help find and rescue the injured.

Why am I writing this? Because if you go to the WattsUpWithThat blog and read Why Are Weather Forecasts So Bad? and the comments from earlier today, you’ll learn that many people have the mistaken impression that meteorologists ‘never get it right.’ While that is often true with monthly and seasonal forecasting, our short term forecasts and storm warnings are usually excellent these days. Warnings need to be taken seriously. And, that is important as tomorrow could be another day of widespread severe weather (see graphic below):

The hatched area is where major tornadoes may occur. Please take the forecasts and warnings seriously as they are issued tomorrow and throughout this storm season.

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Severe Weather Improvements II

Below, I talk about the 99.58% accuracy rate of the National Weather Service’s severe weather outlook issued the day before yesterday’s severe weather event.

Last night, I was watching the storms as they went across the Nashville area. We have relatives in Nashville, including in Mount Juliet. I told Kathleen that “the tornado would pass about five miles south of Mt. Juliet.” That was an excellent forecast.

Here is the map I posted on this blog last night. I derived this data from radar:

The red circle is the circulation that produced the tornado. The arrow is the path of the circulation across the south and east part of the Nashville metro area.

This is the path of tornado, produced by the circulation, as determined by National Weather Service survey.

At 7:43am Wednesday, more than 39 hours before the tornado, I wrote the following on this blog:

Now, here is the best part: Even though this was a non-standard tornado situation, there were effective warnings issued by the NWS for the public and by WeatherData Services, Inc. for its clients. The results, according to the NWS: No deaths and no injuries — even though this tornado was rated F-2 intensity and occurred in darkness.

Even 15 years ago, it is quite possible this tornado would have not been detected and would have occurred unwarned. Deaths might have resulted. We have today’s sophisticated warning system to thank for another lifesaving success.

UPDATE: Here is a good article about the impressive tornado damage. Note the toppled metal electrical towers.

How Much Snow Fell in NYC?

Just ran across this snowfall map of the Boxing Day Blizzard in NYC:

Purple = more than 20 inches. Click to enlarge. 
Now, take a look at the “worst case scenario” forecast from this very blog posted at 8:50 am the 25th: 
The red over Manhattan is 18″ and the gray/pink tinted color inside the red is 20″ or more. The storm was described as a “nightmare.” Gusts were forecast in the 40 to 60 mph range.