What makes a Thunderstorm severe?

What exactly makes a thunder storm “severe”? One of several things:

1. a tornado
2. winds at or above 58 mph
3. or quarter-size (one inch diameter) hail or larger.

Did you know there are different types of thunderstorms?

• Single cell thunderstorms usually occur during the summer months when the air is warm, moist, and unstable, and winds are weak. These thunderstorms, also known as pulse or airmass storms, form as unorganized clusters and have little to no movement.
• Multicell thunderstorms and squall lines are organized complexes of thunderstorms that cover large areas. These storms are more likely to produce severe weather, particularly damaging winds, since they move rapidly across an area. Tornadoes, hail and flash flooding are also possible.
• Supercell thunderstorms are the strongest and most dangerous and can produce long-lived tornadoes, winds in excess of 100 mph, and large hail. Fortunately, these storms are rare.

Bottom Line

The best defense against thunderstorms is to stay inside a building or shelter for protection from lightning, wind, hail, and heavy rain. For tornado protection you need a substantial shelter or basement, preferably far from windows. But don't think a storm is "ignorable" just because there's no tornado, damaging wind events occur 10 to 20 times more often than tornadoes. Initial storm reports often erroneously attribute significant damage to tornadoes when actually strong, straight-line winds from thunderstorms are responsible.

Fortunately, thunderstorms generally pass within an hour. When thunderstorms are expected, stay tuned to your NOAA Weather Radio All Hazards for up to date information. Postpone outdoor activities.

How long does it take to get Frostbite?

How long does it take to get frostbite? Sounds like an easy question but I find many different answers on the Internet (including one tough old New Englander who answers, "never", with proper clothing). Part of the confusion lies in the definition of "Wind Chill". See http://perpetualpreparedness.blogspot.com/2010/01/wind-chill.html for details. There have been two changes.

1st:  In Nov. 2001 the wind chill values were changed based upon a new equations, see http://www.crh.noaa.gov/ddc/?n=windchill. Whereas 15°F used to be extreme cold in 20mph wind, now it's "safe" at all wind speeds and never drops below -11 wind chill.

2nd: Some revised charts appear to use the new wind chill values but kept the color bands the same for exposure times. See this NOAA chart from 2010 which still has 15°F freezing within 5 minutes with strong wind. http://www.srh.noaa.gov/jetstream//global/chill.htm

A new NOAA chart from 2011 (pictured above) updates the color zones. http://antarcticfudgesicles.wordpress.com/afsa-student-page/how-long-does-it-take-to-get-frostbite/ The exposure time colors don't exactly match the wind chill numbers anymore (for instance -40 wind chill is in two different color zones).
Wind chill of -20°F to -35°F (approx) Frostbite in 30 minutes for exposed face, at night.
Wind chill of -35°F to -50°F (approx) Frostbite in 10 minutes.

There used to be a -30-30-30 rule that -30°F with a 30 mph wind could freeze skin solid in 30 seconds. Under the new chart it's -30 & 30mph & 5 minutes for frostbite.

Bottom Line
So what happened to the NOAA charts? During the fall of 2000, the Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM) organized a joint U.S.–Canadian government-sponsored action group to develop, test and implement a new Wind Chill Temperature Index. Human trials were done in Toronto, Canada with 12 volunteers in chilled wind tunnels with thermal transducers stuck to their face while walking on a 3mph treadmill. Brrrrr.

So the new chart is based on solid human evidence of facial skin instead of mathematical modes and time to freeze bottles of water.  See http://www.nws.noaa.gov/om/windchill/images/wind-chill-brochure.pdf for more information.

Hurricane Season

“It was like being in the eye of a hurricane. You'd wake up in a concert and think, Wow, how did I get here?”
-John Lennon

August 1 denotes the start of peak Hurricane season. Here are some hurricane factoids.

• While the overall hurricane season is June-November, the greatest activity is during August/September. 
• A hurricane Watch means a hurricane is possible within the next 3 to 4 days. Be watchful and listen to TV/Radio/Internet/etc for updates.
• A hurricane Warning means a hurricane is expected within 2 to 3 days. Find out if you are in the hurricane path and what action is required: i.e. board up the house or evacuate. Keep a radio/TV on at all times because hurricanes can change path and suddenly you're in the danger zone.
• There are 5 categories of hurricanes, based on the Saffir-Simpson Wind Scale—http://www.ready.gov/america/beinformed/hurricanes.html. Category 1 is the weakest. Fortunately Category 5 is rare.
• No matter what category, all hurricanes are dangerous. A storm is not called a hurricane unless wind speeds are at least 75 mph.
• And remember it’s more than just wind. Storm surge (flooding) is the major cause of death and damage in coastal areas.

Bottom Line

Each Hurricane is different. Some include tornados, others heavy rain. Just becuase the last one you went through was a snoozer does not mean every hurricane will be so gentle. Treat every hurricane with the respect it deserves.

More Twisters!

"Then the air was filled with 10,000 things. Boards, poles, cans, garments, stoves, whole sides of the little frame houses, in some cases the houses themselves, were picked up and smashed to earth. And living beings, too. A baby was blown from its mother's arms. A cow, picked up by the wind, was hurled into the village restaurant."
- St. Louis Post-Dispatch, March 20, 1925

Last month the South was hammered by tornadoes. Two weeks ago a massive thunderstorm created 137 tornadoes, killing over 180 people, and destroying sections of Tuscaloosa, Birmingham, and Huntsville, Ala. Do you know what to do if a tornado is reported?

* Know where to go
If caught outdoors, where is the nearest shelter? If you live in a mobile home, leave it!  A tornado can tip, roll, and destroy mobile homes.

* Know what to bring to a shelter
After the tornado has passed you may find your home completely destroyed. Your go-kit should include identification, copies of important financial documents, insurance contracts, important contact information, and anything else you'll need to access your money and rebuild.

* Know who to contact
Have a relative outside your community serve as an emergency contact so if family members are caught by the storm in different locations, they can call their status and state what shelter they can be found at.

* Listen for NOAA tornado watches and warnings
As described yesterday, there are free and fee services that can alert you to a NOAA weather event in your area. NOAA weather radios will wake you up if a storm system arrives overnight, when you're sleeping.

Tornado WATCH = keep a eye to the sky. Conditions are favorable for tornadoes so prepare.
Tornado WARNING = a funnel cloud or its precursor has been spotted. Get to safety immediately.

* Know the local counties
If there's a Tornado Warning for Rockland county - how far away is that? Should you worry? At home I know the neighboring NY counties but no clue about Connecticut where I work.

* Get away from windows
The main danger is flying debris from high winds. Find a room that is window free if possible. Go to the lowest room or basement in the house (tornadoes can rip off the tops of homes.)  Duck under a sturdy piece of furniture and hang on.

* What to do if outdoors
If you are outdoors, lie flat on the ground in the lowest spot you can find and cover your head with your arms. Ditches or holes are great but don't spend so much time searching that the tornado catches you standing up.

* After the twister passes...
Don't enter damaged buildings - they may collapse on you. Leaky gas mains may start fires or explosions. Stay far away from downed power lines. Keep listening to weather reports, since the storm may be part of a system spawning several tornadoes.

Bottom Line

Here are some tornado myths from the Christian Science Monitor:

Myth: If a tornado comes, it will inflict less damage if you open your windows to equalize the air pressure inside and outside the structure.
Fact: don't bother; the tornado-blown debris will shatter your windows. It's not pressure but high winds that will cause damage.

Myth: If you're caught outside when a tornado approaches, head for a highway underpass. It will shelter you.
Fact: an underpass won't provide much shelter from wind or debris. Lie flat in a ditch instead.

Myth: A tornado can't happen here.
Fact: They happen in every state.

It's a Twister!

“Coward: One who, in a perilous emergency, thinks with his legs.”
-Ambrose Bierce, The Devil's Dictionary

On Instapundit.com I read about a weather warning system that sounds promising (but I have not tried so I can not vouch for it.) WeatherCall.net, http://www.weathercall.net/wc_whatisit.html, will register one location for $10/year and send you email, text message, phone call, etc if there is a severe weather warning issued by NOAA.

Subscribers may register one location, 3 telephone numbers and 3 email addresses for a nominal fee of $9.95 dollars per year. When severe weather is approaching the registered location, the system will call all the telephone numbers simultaneously, delivering your meteorologist's warning message, and send a message to all registered email addresses with a graphical depiction of the warning on a localized, interactive Google map.

Not interested? How about a weather radio that turns on for alerts?

Bottom Line

I admire entrepreneurs that start companies like this. (Why didn't I think of it? I can envision writing the code to make a system like this.) NOAA provides tons of information for events all across the nation. So the trick is filtering it to only a region of interest and then creating the phone calls and emails.

I found a list of other companies with similar services at Yahoo. I also found some sites, supposedly free, that I'll try out. You may want to opt out of ads from their sponsors to avoid spam.

http://www.emergencyemail.org/
https://registration.weather.com/ursa/alerts/step1
http://www.weatherusa.net/members/login.php?mode=new

Winterize your House

“Winter is the season in which people try to keep the house as warm as it was in the summer, when they complained about the heat” - anon

Kiplinger.com had published Your Fall Home-Maintenance To-Do List with 9 ways to winterize your home:

9. Have your lawn-irrigation system professionally drained.

8. Trim landscaping.

7. Turn off exterior faucets.

6. Add extensions to downspouts so water runs at least 3 to 4 feet away from the foundation.

5. Clean the gutters.

4. Caulk around windows and doors.

3. Make necessary roof repairs.

2. Buy a programmable thermostat.

1. Tune up your heating system.

Bottom Line

Forecasters are predicting an extra cold winter in the North East due to a weak El Nino. Prepare now!

Flash Floods

“The only thing that stops God from sending another flood is that the first one was useless.”- Chamfort (French playwright)

When I picture death by weather, I can imagine tornadoes and lightning but the number-one weather killer is not so obvious: drowning in flash floods. The national 30-year average (1977-2006) for flood deaths is 99. That compares with a 30-year average of 61 deaths for lightning, 54 for tornadoes and 49 for hurricanes

A flash flood can occur quickly –within minutes of heavy rain, a dam/levee break, or ice jam break. A flash flood is also fast moving – you cannot out run it. Your best bet is to move upwards to high ground above the flood level. If the police or radio issues a flood warning – move immediately.

When driving remember the slogan, “Turn Around, Don’t Drown” when you see water covering the road. Half of all drowning occur inside a car. Don’t park your car next to a river if you can avoid it. I had a friend attend a wedding and, upon leaving the church, discover that a nearby river had crested and the car of every guest was flooded.

When camping, pitch your tent away from rivers and streams on higher ground. You never know what will happen while you’re sleeping. Once, when the sky was crystal clear, I decided there was no reason to put the rain cover over my tent. I awoke with rain falling upon me. Another time my wife & I were surprised to find that rain or dew had frozen to the outside of our tent overnight. We had no idea it was that cold or wet.

Bottom Line

Water is a powerful force – eroding mountains along river valleys like the Grand Canyon; but it can also move in mysterious ways. I was once surprised while attending a party at a boat club on the Hudson River. The river reached an unusual high tide and I found the clubhouse completely surrounded by water when it was time to leave. We were able to keep our shoes dry by climbing over some planks.

www.floodsafety.com/
www.nws.noaa.gov/om/brochures/ffbro.htm

P.S. A camping joke…

Sherlock Holmes and Dr. Watson go on a camping trip, set up their tent, and fall asleep. Some hours later, Holmes wakes his faithful friend.

'Watson, look up at the sky and tell me what you see.'

Watson replies, 'I see millions of stars.'

'What does that tell you?'

Watson ponders for a minute. 'Astronomically speaking, it tells me that there are millions of galaxies and potentially billions of planets. Astrologically, it tells me that Saturn is in Leo. Timewise, it appears to be approximately a quarter past three. Theologically, it's evident the Lord is all powerful and we are small and insignificant. Meteorologically, it seems we will have a beautiful day tomorrow. What does it tell you?'

Holmes is silent for a moment, then speaks.
'Watson, you idiot, someone has stolen our tent.'

Lightning Myths

“There are only three things that can kill a farmer: lightning, rolling over in a tractor, and old age.”-Bill Bryson

According to the National Weather Service, “lightning kills on average more than 70 people and injures at least 300 each year in the U.S. Most people assume they will never get hit and yet they pour money into lotteries where your chance of winning is less likely than your odds of being struck by lightning. So the “Hey, you never know” lottery philosophy needs to be applied to lightning too.

Much about lightning that people think they know is false. Here are some common myths:

• Lightning never hits the same place twice
  False. The top of the Empire State Building is hit a hundred times a year.
  
• I’m safe if there’s blue-sky overhead
  False. Lightning can easily travel more than three miles from the thundercloud. 10-15 miles is rare but can happen. So distant clouds can be a local concern. Don’t wait for rain to stop a sports game. If you see dark, angry clouds approaching, call the game.
  
• A car is safe from lightning because of the rubber tires
  False. After traveling several miles through air, lightning will laugh at two feet of rubber. It is the metal body of the car that directs lightning around you and keeps you safe. This also means that fiberglass cars, bikes, motorcycles, and open cabin tractors will NOT keep you safe. Likewise rubber sneakers or a rubber rain jacket offer NO protection.
  
• Lightning is attracted to metal or take off anything metal
  False. Metal does not act as a lightning magnet; bolts are just as happy to hit trees and stony mountains. HOWEVER, when lightning does strike, it can travel over 100 yards through metal fences, cars, bleachers, etc.
  
• You can become electrified by touching a lightning victim.
  False. Humans are not batteries and do not store electricity. Give CPR immediately.
  
• Trees will protect you from lightning
  False. Anything tall attracts lightning and being under a tree is the second leading place for lightning deaths.
  
• I’m safe from lightning inside my house
  Yes, But… A lightning strike on the house can cause current to run through phone wires, electrical cords, metal window frames, water pipes (even plastic), etc. Stay away from windows and away from phones and appliances.
  
• A surge protector or UPS will protect my computer against lightning strikes
  False. A surge protector is great for normal, everyday spikes in electricity but lightning is off the scale. The only sure way to protect computers, TVs, etc during a storm is to unplug them.
  
• If lightning is about to strike you outdoors, lie flat on the ground
  False. Lightning can travel over 100 feet though the ground so you maximize your exposure by lying flat. Instead use the ‘Lightning Crouch’ – feet together, crouch low, head tucked, ears covered. You want to be low down with minimal ground contact.
  
• Lighting won’t strike water
  False. Lightning can strike water so boaters and swimmers are not safe in a storm.
  
• Stand near a tall object so the lightning will strike it instead of you.
  False. Lightning is very fickle. It prefers tall objects but it can and does strike anything it wants to. Even if the tall object is hit, you can still be fried if within 100 feet of the strike.
  
• Most lightning injuries occur to golfers
  False. Common victims include postal workers on foot, telephone repairmen, farmers in large fields, joggers, hikers, campers and of course, golfers.
  
• A lightning strike is always fatal
  False. A strike will instantly kill 20% to 30% of the time. Sometimes the heart is stopped and immediate CPR is needed. Sometimes lightning just flashes over the outside of a victim, blowing off the clothes but leaving few external signs of injury and few, if any, burns.

Bottom Line

This myth list is for information only. There is still much about lightning that is not understood. No guarantee of lightning safety is stated or implied.

Resources
www.lightningsafety.noaa.gov/pdfs/LightningMyths-1.pdf
www.uic.edu/labs/lightninginjury/ltnfacts.htm
www.wvlightning.com/lmyths.shtml
www.essortment.com/hobbies/lightningthunde_scqd.htm