Saturday, June 1, 2013

Tornado Weather

A tornado in Oklahoma, May 31, 2013  Image credit: ABC News
Today is Saturday, June 1, 2013.

It's tornado season again, and since I'm planning to drive to the Kansas City area, I'm concerned about the weather.  The current storm system seems to be siting on us, and hasn't budged much.  I'm hoping that next weekend's weather will be much nicer.

This year's tornado season had a late start, and has been rather quiet until just recently.  As of May 31, the National Weather Service’s Storm Prediction Center recorded a preliminary count of 207 tornadoes in the month of May, and 441 for the year so far.  That number will go up, most likely after last night's  nasty weather, which has resulted in at least 9 fatalities. The United States experiences 1200 to 1300 tornadoes every year. 

Last year had the most active tornado season on record, with a total of 1691 tornadoes across the United States.  In 2011, 553 people lost their lives in tornadoes. The Joplin, Missouri tornado was the most deadly, killing 157 people. That tornado ranked as the seventh deadliest tornado in U.S. history since record-keeping began in 1950. 

In places like Moore, Oklahoma, where the wreckage from the F 5 storm on May 20 has not been completely cleaned up, there was a new danger – jagged pieces of wood, metal and glass that could become deadly flying projectiles in the strong winds.  At least 2 people are dead after last night's storms. There was chaos on Interstate Highway 40, a major east-west highway that cuts across the middle of the continental United States from Wilmington, NC to Barstow, CA, as the storm hit the Oklahoma City area right at evening rush hour, stopping traffic and essentially making motorists "sitting ducks". 

For all but four of the tornado victims in 2011, both a tornado watch and a tornado warning were in effect before the storm arrived.  99.3% of the people in the path of the 2011 tornadoes had some warning of danger.  For those who don't experience tornadoes often, a tornado watch is issued when the conditions are favorable for the formation of tornadoes.  A tornado warning means that an actual funnel cloud has been sighted and that it is heading toward your area.  For every four warnings that are issued, only one tornado touches down, so some people court danger by ignoring the warnings.

Most people don't have to wait for a warning, though.  The U.S. Weather Service is very good about warning people days ahead of time that there may be severe storm activity, and those who live in tornado-prone areas know enough to keep an eye on the clouds, and they tend to keep their TV or radio tuned to a station that will advise them if they need to head to shelter.  Some people even have a special weather radio that is pre-tuned to a network of stations that give a continuous weather broadcast.  The sound is typically turned down, but the radio comes equipped with flashing lights or a loud alert sound that goes off when specific types of weather occur in specific areas.  Back in 1990, people were lucky to get 5 minutes' warning of a tornado strike.  These days, people often get 12-15 minutes' warning, thanks to modern technology.   Still, if you are away from your TV, radio, or computer, and you aren't paying attention, you may find yourself in a considerable amount of danger.

Some tornado facts:  

Tornadoes are most likely to occur in mid- to late afternoon, between 3 and 7 p.m., but they can happen anytime.

Tornadoes usually move from southwest to northeast, but tornadoes associated with hurricanes can move from an easterly direction.  A tornado's path is not straight, but zig-zags erratically. 

The average tornado's path is about 4 miles, but may be as long as 300 miles.  In 1917, a tornado lasting 7 hours and 20 minutes traveled 293 miles across Illinois and Indiana.

The average tornado is 300 to 400 yards (900-1200 feet) across, but some have been more than a mile in diameter. 

Tornadoes typically travel 25-40 miles per hour, but may remain stationary or travel up to 70 miles per hour.

A tornado cloud is very dark and heavy, and there is definite circular movement in the cloud. 

Tornadoes often follow a rainstorm, and sometimes hail.  There is typically a heavy downpour immediately to the left of the tornado's path.

A tornado's sound has been described as roaring, like a train speeding through a tunnel, or the roar of many engines.  Just before a tornado, there is a stillness, and you may notice that the birds are not singing.  They are very smart - if they are not singing, you should be in a tornado shelter.

There is still a lot of misinformation about tornadoes.  I'd like to bust a few tornado myths here, if I may. 

When a warning sounds, the earlier the warning, the better.  Not necessarily, because then people tend to think they have more time than they really do.  They wonder whether they should go put the car in the garage or bring in the lawn furniture.  Frankly, if you haven't done that by the time the siren sounds, you are too late.   Also, people don't like spending more than about 15 minutes in a shelter.

When a tornado warning sounds, you should open all the windows in your house to equalize the pressure.  This will not help, and may keep you from getting to shelter in time.  As well, you should not go near windows when a tornado hits.  Besides, if your roof is ripped off, the pressure will equalize all by itself.

Tornadoes don't hit the big cities.  Bunk.  There have been tornadoes in Dallas, TX,  Oklahoma City OK, St. Louis, MO, Miami, FL, Minneapolis and St. Paul, MN and Salt Lake City, UT.  When a tornado hits a densely-populated area, there is lots more debris to toss around, making these tornadoes especially dangerous. 

Tornadoes do not occur in the mountains.  Oh, yes, they do.  Damage from an F3 tornado has been recorded at an elevation above 10,000 feet.  One hiker took a picture of a weaker storm in the mountains of Utah. 

Tornadoes don't cross rivers.  They do and they have. They temporarily become "waterspouts" while over the water, which doesn't slow them down much.   In fact, the Nachez, MS tornado of 1840 tracked right down the Mississippi River.  A tornado in 1953 crossed the Brazos River in Waco, TX, and one twister jumped the Mississippi River in St. Louis, MO, in 1896.   

Tornadoes can occur in the middle of the night, and even during the winter.  The likelihood of a tornado happening in winter is pretty low, unless you live in the southern part of the United States.  Tornadoes do sometimes happen in the middle of the night.  That's why people in tornado-prone areas should have a weather radio turned on before they go to bed or keep their cell phone handy, if they have asked to be sent text warnings.  My mother, who grew up in tornado-prone Kansas, taught my siblings and me that if she said, "Go to the basement right now," we were to go, pronto. We were also taught that when a tornado watch was put into effect, we should put on our shoes and prepare a small radio and a blanket to be taken with us to a pre-identified shelter area, if necessary.  We were told to go directly to shelter when the tornado siren sounded, and stay there until an all-clear was given.  Mom never did get much sleep when there was a tornado watch issued for the wee hours of the night. 

Tornadoes can pick people, animals and items up, carry them some distance away, then set them down without injury or damage.   It's true, they can, but this is an exception, rather than the rule.  Naturally, occurrences like this get reported, because they are so miraculous, but don't let that give you the impression that these events are normal.   I do remember hearing that one little boy was sleep in his bed and woke up in a cornfield miles away.  I also have some cousins who lived in northern Minnesota, who were all taking a nap on Sunday afternoon, when a tornado struck their farm.  The barn was obliterated except for the stone foundation, and all the other buildings on their property were gone, as were all the trees around the house, but the house was left virtually undisturbed.  People have found precious photographs miles away and have made efforts to get them back to their owners.  An event like that always manages to get into the papers.

When driving, you can protect yourself by hiding under a bridge or freeway overpass.  Not really.  The bridge may protect you somewhat from falling debris, but the area under a bridge can actually become a wind tunnel that collects debris. Whatever you do, don't abandon your vehicle on a bridge and attempt to climb down under the bridge, because the tornado may end up turning the abandoned cars into a mangled mess that will make it hard for police, fire trucks and ambulances to get across the bridge later.  You should only consider this option if you can hide on the ground next to the supports.  Otherwise, you should try to get away from the bridge area and lay face-down in a ditch by the roadside with your hands covering your neck.   Frankly, I think people who drive in tornado weather are not being very smart, so I guess it doesn't surprise me that some of them try dumb stunts like this.

A vehicle can outrun a tornado.   Tornadoes can travel at up to 70 miles per hour, and often change directions suddenly and erratically.  A better option is to stay off the road altogether.  Failing that, park your car and seek shelter in a building when the clouds turn black, or lie flat, face-down, in a ditch by the side of the road with your neck covered by your hands. 

An F5 tornado is the strongest.  The Fujita scale goes up to F12. However, the wind speeds of an F12 storm would exceed Mach 1.0 (over 700 miles per hour), which makes an F12 tornado a highly unlikely event.  An F5 tornado can destroy just about everything in its path, and since wind speed is generally established by looking at the damage after the fact, it would be hard to say if a tornado were F6 or stronger.   It's not currently possible to accurately measure wind speed inside a tornado, but it is conceivable that speeds above 319 miles per hour might possibly be recorded.  That will be for future generations to establish. 

Tornadoes are more likely to hit mobile home parks.  Not really.  It may seem that way because they tend to sustain more damage in a tornado.  Mobile homes are not good protection against even the weakest tornado.  Now that it is possible to predict severe weather earlier and more accurately, tornado-prone communities with lots of mobile home parks should consider building community shelters.  If you live in a mobile home, figure out where you could go for shelter in a storm.

A tornado can drive a straw into a telephone pole without breaking the straw.  This is true, although very rare.  The point is that even a piece of straw can be deadly while flying through the air in a tornado.  

I am safe if a tornado is not coming directly toward me.   Unfortunately, this is not true, because tornadoes are so unpredictable.  The safest place to be in a tornado is in a shelter.  

Here's what to do if there is a tornado warning.

If your area is prone to tornadoes, or even if it's not, you should identify a safe place in your home to use as a shelter area.  The safest place is away from windows and underground.  Next best is a small room (typically a bathroom or closet)  in the center of your home, away from outside walls.  Duck under a sturdy piece of furniture, such as a table, if you can, and find something to hang on to.
If you are in an apartment building, go to the lowest floor, and stay away from doors and windows. Failing that, hide in the bathroom.

Especially during tornado season, each person in your home should have a "go kit" ready.  The basic kit is a blanket, flashlight with good batteries, portable radio, and cell phone, and everyone should be wearing covered shoes, not just sandals or flip-flops.  Your most important papers should all be in one place, where you can grab them if there is a tornado, fire, or other disaster.  If you have more time to prepare, you can grab a bag with an extra set of clothes, your ID, bottled water, and perhaps a candle and some matches. 

If your family is separated during a storm, identify in advance a relative or friend who lives outside your area that family members can call to give status updates.  It's often easier to get calls through from a storm area to the outside, rather than the other way around.  Make sure that person knows you are doing this, and offer to do the same for him or her.

If you are in a tornado-prone area, have weather updates sent to your cell phone.  (I was in a bookstore in St. Paul one day when my phone received a text alert.  I was paying for my purchase and the manager was right there at the cash register.  I notified the manager of the warning and she forced all the shoppers to exit the store and proceed to the shelter area in the mall.  Meanwhile a tornado was touching down in downtown Minneapolis, just a few miles away.)

Know what county you are in, so that you can interpret the warnings on TV or radio.  This is important when you are traveling.  Know before you go, especially if you are doing a long road trip. 

If you are outdoors, find the lowest spot possible and lie flat, face down, covering your neck with your hands.  

After the tornado passes, do not enter damaged buildings, and be careful not to go near downed power lines or leaky gas mains.  Some storm systems spawn multiple tornadoes, so remain alert until the storm system clears up. 

Remember that although there are many tornadoes each year, they are still rare events, and many people can go a whole lifetime without actually experiencing a live tornado, even in tornado-prone areas such as Kansas, Nebraska and Oklahoma.  :-)

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