Vince_Condella's Blog

This has been one chilly month - or so it seems.  Today was no bargain.  A breeze off the lake and Lake Michigan surface water temperature around 40 degrees: yikes, that means any location near the lakeshore has no chance of warming up.  And sure enough, today's high near the lakeshore was only in the mid 40s.  Mitchell Int'l. Airport only reached a high of 49, while Waukesha made it up to the low 60s.

Will it ever warm up around here?  This is the time of year when spring seems to take forever to get here.  But adding up the numbers for this month so far shows that we have had 6 days colder-than-normal, 4 days warmer-than-normal, and 2 days right at normal.  Adding it all up yields a temperature for the month that averages only 0.1 degree below normal.  Yep, only one tenth of one degree. 

As a frame of reference, our average high and low for this time of year is 65 and 45 based on the past 30 years of data.  So today's high of only 49 was well below the long-term average.  Also keep in mind that the "official" weather stats for southeast Wisconsin measured at Mitchell Int'l. Airport, and this location isn't always representative of southeast Wisconsin.

Hang in there.  One of these days spring weather will arrive and stay around for a few days.

Another weekend comes to a close, and on this cloudy and rainy Mother's Day I ponder a few things from the world of weather.  The catastrophe that is Myanmar (formerly Burma) is astounding.  The death toll keeps climbing as millions of people are affected by the tidal wave, wind, and flooding rainfall from Cyclone Nargis last weekend.

Myanmar is controlled by a military junta, so getting aid into the country is a monumental task.  At first I thought it was disingenuous of the Bush Administration to chastise the Myanmar government, especially after the debacle following Hurricane Katrina.  But then the Myanmar government made the plight of Katrina victims pale in comparison.

The leaders of Myanmar, according to news reports, are stamping their name on the incoming containers of food and water from other countries around the world.  Apparently they want to look benevolent in the eyes of their citizens.  And they are also blocking and/or slowing other incoming aid.

The cyclone hit at the worst spot in Myanmar, a coastal region barely above sea level with few trees or other vegetation to absorb the highs waves and water.  Plus, many residents live in sub-standard housing with poor construction.

My thoughts this weekend also go out to the victims in our country of yet another tornado and severe weather outbreak.  The death toll from Saturday's storms was 11 and climbing in places like Missouri and Arkansas.  And today the same line of storms is raking across the Carolinas and Georgia.  This has been a brutal winter and spring for the south and southeast, going back to the deadly tornadoes on Super Tuesday in February.  Fifty-eight people lost their lives to tornadoes in February alone, and the death toll for 2008 so far will probably top 90 once final recovery efforts are completed for this weekend's storms.  Last year the death toll was 81 for the entire year, and the last three years have averaged 62 fatalities.

The main storm track has been cutting through the southern U.S. since the first of the year.  Here in Wisconsin we remain on the northern edge of that storm track, and as low-pressure centers pass to our south, we stay on the cool side of weather systems with winds off the lake.  Meanwhile the warm and humid air in the southern half of the storm systems affects the southern states.  This persistant southern storm track could be a result of the La Nina, or abnormal cooling of the equatorial Pacific Ocean, but there may be other causes as well.  With the enormity of the atmosphere, it's not a safe bet to pin one effect on one cause.

Finally, I was getting a chuckle reading the comments from my previous blog about jet contrails - chemtrails.  I think most of the comments were written by the same person just logging on by different user names.  But this subject always gets a huge reaction, so I was expecting it.  Everybody is welcome to their own opinion, and it is important to read about a subject and educate yourself about what you hear and read in the media.

A full-out discussion of this is wonderful.  But I am always amazed at how the naysayers of contrails-chemtrails claim that I am toeing the company line, or that I am withholding vital information that could save the planet from chemical spraying.  I even got one mail from somebody who claimed that I simply read what somebody else prepares for me.  So my discussion of contrails on my TV weather report the other night, according to the e-mailer, was just me reading from a prepared script.

Note to e-mailer:  prepared script?  Just where is this huge editorial staff writing and preparing all my material for me?  Sorry to disappoint you, but it is just me back here in the weather office, doing my own research and preparing my own weather reports.  Now if you'll excuse me, I've got to get back to watching old reruns of The X-Files and scanning the latest Drudge Report.

The conspiracy theorists know how to spoil a nice day.  Every time a gorgeous display of jet contrails graces our sky, certain people will pop up and claim that the U.S. government is spraying us with chemicals.  The contrails, a contraction for "condensation trails", suddenly become chemtrails.

I'm all for freedom of belief.  Everybody is entitled to their own opinions in life.  But the chemical thing is wrong.  These are simply jet aircraft depositing water vapor as part of the exhaust from their engines.  When the water vapor comes in contact with air that is well below freezing, as it is at 25,000 feet and higher even in the middle of summer, the vapor immediately turns to ice crystals.  These ice crystals will sometimes form a long string of man-made cirrus clouds.

Some days there are no contrails even with commercial jet aircraft flying high overhead.  Other days the contrails are long-lasting and spread out to form a layer of cirrus clouds.  Why the difference?  Some people have claimed that the government only sprays us with chemicals on certain days.  This is not true.  The reason is far less sinister.

The appearance of contrails depends upon the moisture content of the air at the altitude of the aircraft.  If the air is very dry aloft, aircraft will leave either no contrail or a very short one.  That's because any moisture expelled by the jet engines evaporates immediately, so any ice crystal that forms won't last long.  If the atmosphere at the altitude of the aircraft is more moisture-laden, the water vapor-turned-ice crystal will remain for a long period of time.  Winds aloft will help spread out the contrail.

In areas where commercial jet traffic is high, many contrails will criss-cross the sky and form cirrus clouds.

Professor David Travis at UW-Whitewater has done some interesting research on the effect of contrails on climate.  He used the days following September 11, 2001, as part of his control set of data.  This was a period, you may recall, when all commercial air travel was suspended and there were no contrails anywhere across the United States.  It's a fascinating look at how sensitive our climate can be to certain changes.  Check out an on-line article about the study at THIS LINK.

This Saturday, May 10, is National Astronomy Day, and our local astronomical organizations will have public events for those curious about the night sky.  This is the weekend to introduce somebody to the wonders of the universe, and there is no better ambassador for the science of astronomy than local amateurs who love their hobby.

Amateur astronomers around the world contribute daily to the body of knowledge of our solar system, our galaxy and our universe through their discoveries, often using home-built telescopes and computer-aided photo equipment.  We are lucky here in southeast Wisconsin to have strong local amateur astronomy clubs that will help anybody get interested in the stars and planets.

The Milwaukee Astronomical Society (MAS), a long-standing amateur organization based out of their observatory in New Berlin, will be holding public viewing and talks about our Moon this Friday evening.  They will also have telescopes set up for public viewing of the Sun on Saturday at the Wal-Mart Supercenter in Mukwonago.  The Friday night session begins at 7:30pm, and Saturday's event starts at 11 a.m. and goes all afternoon.

For information about the two-day event being put together by the folks at MAS, including directions to their New Berlin observatory, to go their web site at Milwaukee Astronomical Society.

Meanwhile, the Northern Cross Science Foundation, another wonderful local astronomical group, will hold public viewings of the stars and planets from their new observatory at Harrington Beach State Park (northern Ozaukee County) this Friday evening beginning at 7 p.m.  Saturday will be an all-day astronomy fest at Harrington Beach starting at 2 p.m. and going all the way through the evening.  There will be talks and demonstrations about various topics in astronomy, as well as solar viewing during the day and stellar and planetary viewing in the evening.

To learn more about the events at Harrington Beach State Park, go to their web site at Northern Cross Science Foundation.

Get outside and look up this weekend and get turned on to the wonders of our universe!

That's one of the most common questions I get from viewers.  The old "cooler near the lake" is a spring and summer mantra in this part of Wisconsin.  Typically you will hear a forecast with two temperature numbers for daytime highs:  lakeside and inland.  But rarely do forecasters tell you where "inland" is located.

The distance to "inland" depends on the wind speed and, to a lesser extent, the direction of the wind.  It makes sense that a faster wind speed will carry cool air from the lake a farther distance inland than a lighter wind speed.  A wind over 15 m.p.h. will usually take the cool air all the way to Highway 45 in western Milwaukee County.  It may take a few hours for the cool air to move inland from the lakeshore to Wauwatosa, but typically it arrives by 10 a.m. or 11 a.m.

Slower wind speeds mean very little distance to "inland".  In fact, when the average wind speed is less than 10 m.p.h., cool air from the lake may not make it very far past the I-43/I-94 north-south corridor.  On a light wind, warm, sunny day, Milwaukee's lakefront in May could be 55 degrees but downtown West Allis may be 70 degrees or higher.

Wind direction dictates the coolness of the air more than the distance it travels inland.  A north-northeast wind travels nearly the entire length of Lake Michigan simply because the lake is oriented north-south.  A northeast trajectory of an air parcel means it gets to spend a long time travelling over the chilly waters of the lake.  On the other hand, an east or southeast wind has a lesser trajectory and may not pick up as much cold air over the lake surface.

As a forecaster, I tend to keep the lakeside-inland temperature difference greatest with a northeast wind, slightly less for an east wind, and even less for a southeast breeze.  I will check the lake surface temperature from the mid-lake buoy as well as the harbor water temperature reports near the lakeshore.

Meteorologists also need to make it clear in their forecasts where "inland" is located.  It's impossible to list the forecasted temperature for every town and city in the viewing area, but at least a couple of locations should be referenced, e.g. today's high will be 55 at the lakefront and 75 in Waukesha, or 75 west of Highway 45, etc.

It's the little attention to detail that makes a forecast usable for everybody.  And of course we all know that if going to the lakeshore this time of year doesn't cool you off enough, you can always jump into the lake.  Come to think of it, I've had a few people tell me to do that on occasion!

The terrible news out of the country of Myanmar (formerly Burma) this weekend was the possible death of more than 10,000 people due to powerful Cyclone Nargis.  The huge storm came on-shore with a giant storm surge of wind and wave that buried people in a wall of water.  It is the deadliest natural disaster to strike Myanmar in its recent history.

The satellite image below is of the cyclone on May 1 in the Bay of Bengal near India.  Winds in this cyclone were estimated to be up to 135mph, ranking the storm as a category 4 on the Saffir-Simpson scale used to rank Atlantic hurricanes.  (the most severe is a category 5)

Notice that we have two storm names here: cyclone and hurricane.  What's the difference and is there one?  Some people today told me they thought a tornado was a cyclone and yet they realized that Cyclone Nargis was much larger than a tornado.  The confusion comes from a classic Hollywood movie, "The Wizard of Oz".  Auntie Em told Dorothy to take cover because a cyclone was coming, using the common word at the time (1930s) for a tornado in the central Plains.

In truth, a cyclone is a hurricane that is located in the Indian Ocean.  Yes, Cyclone Nargis was a large hurricane.  But in different parts of the world, these giant storms go by different names.  A hurricane that occurs west of the International Date Line is known as a typhoon, and one that forms near Australia is sometimes called a Willy-Willy.

As you can see from the map above, part of the power of Cyclone Nargis was where it came onshore in Myanmar:  at a point where the continental shelf waters were very shallow.  This allowed the storm surge of high waves to grow even taller than normal and swallow up the coastal areas.

By the way, in this country, meteorologists know a cyclone to be a large weather system on the scale of 500 miles or more consisting of a surface low-pressure center and a large precipitation shield.  You will often see these extra-tropical cyclones (outside of the tropics) as the large red letter L on a weather map associated with a large area of rain and/or snow moving slowly across the country.

It seems like 2008 may be a banner year for tornadoes, and that's a banner we don't want to unfurl.  More twisters and more deaths on May 1-2 in the southern Plains continued the trend of a stormy winter and spring in the southern United States.

If you saw any of the national network coverage of this tragedy late last week, you may have heard the on-scene reporter breathlessly stating that "the storms struck without warning, there were no sirens."  I've blogged previously that outdoor severe weather sirens are not meant to be heard in the house so I won't rant anymore about that subject.  But as with every large tornado outbreak and deadly storm, the phrase "it struck without warning" will always be a part of the news report whether it is true or not.

Keep in mind that if a tornado watch or severe thunderstorm watch is in effect for your area, any incoming thunderstorm has the ability to produce a tornado.  A watch needs to be taken seriously.  Don't wait for a warning to be issued before you become diligent.

The Storm Prediction Center (SPC) issues a running total of severe weather events for the year, along with comparative data for other years.  Check the latest numbers and graphs at two links....HERE and HERE.

The highlights show that we have had 731 tornadoes so far in 2008.  This is a preliminary number, however, and will no doubt be less when all site surveys of tornado damage are completed.  Total tornado numbers for previous years are:  1,095 (2007);  1,106 (2006); and 1,264 (2005).  So even our preliminary numbers for this year are high.

Tornado deaths so far in 2008:  76 fatalities.  That's deadly.  Total fatalities due to tornadoes for previous years:  81 in 2007, 67 in 2006, and 38 in 2005.

The orioles are back!  Woo-hoo.  It's May 1 and this is a sure sign of spring.  Well, okay, I'll admit it - they come back this time every year.  But hey, so what.  It's great to see these colorful birds.  Technically its the Northern Oriole and they have been wintering in the warmer climes of Central and South America.

The photo above is of a male northern oriole.  The female is duller in color but equally exciting to see.  And the best way to lure orioles to your backyard is to put out oranges.  Slice an orange in two and put both halves face up.  The birds love the energy they get from eating the oranges.  As you can imagine, they've depleted much of their energy during the long migration north.  Plus, the oranges will also attract other birds like the house finch, a small reddish bird (male) that is very common around here all year long.  Photos of a house finch are below.

The male (left) and female house finch.

Another bird that has been sighted in our corner of the state today is the rose-breasted grosbeak (see photo below).  This is another bird that has migrated from Central and South America where it spends the winter.

The male rose-breasted grosbeak.

The male grosbeak is very distinctive in its coloration.

It is stunning to think the distances these tiny birds travel each year.  No wide leather seat, no in-flight meal (expect the kind they can catch in mid-flight), no baggage check-in, and no long lines at the security checkpoint.  Our feathered friends go a long way to survive the cold of winter.  Which makes it even more amazing to think that some birds don't migrate at all, like the cardinal and the black-capped chickadee.  They hunker down and tolerate our coldest days.  Well, at least they have the advantage of not having to deal with potholes!

Welcome back, birds of spring.

Thursday, May 1, is a classic reason why I don't use probability of precipitation (POP) in my forecasts.  POPs are the 30% chance of rain, or 80% chance of rain - terms that you often hear in the weather forecast.  But not at FOX 6.  Why?  It's confusing and often misleading.

The National Weather Service (NWS) forecast for Thursday is calling for a 50% chance of showers.  This is not a rap against the NWS forecasters.  These people are top-notch and many of them can forecast circles around me.  But I think this is a procedural thing for them.  I believe it is required that they include POPs in their precipitation chances.

The way I see the weather situation for Thursday, we may not see any raindrops around here until after 3 p.m.  That means that much of the daytime hours will be dry.  It looks like there will be enough dry air at low-levels of the atmosphere to keep incoming moisture from reaching the ground.  In fact, Thursday morning may feature some sunshine.  Our FOX 6 forecast reflects that scenario.

I may be totally wrong about Thursday's weather, but I just don't see where making a blanket statement of 50% chance is telling our viewers information that will be helpful in planning their day.  If I want to play golf in the morning, go for a morning walk with the dog, or maybe even a morning bike ride, 50% chance for the day won't help me much.  But if I hear that there will be some morning sun and then a chance for showers after 3 p.m., then I can plan my day better.

I bring this up because many people want to see the POP in a forecast.  They ask me why I never use it.  My response is that I would rather give them a specific forecast based on the timing of the event.  I'll admit that it would be easier if I just went on the air and gave a 50% chance for Thursday and that was it.  By being specific and actually stating that I expect no showers before 3 p.m., I'm setting myself up for a busted forecast.  If the dry air doesn't hold out and we get raindrops around Noon, I'll look bad.

My response to that is "so what".  People tune to my forecast to hear specifics.  I'm sure many of the NWS forecasts share my view, but as I stated earlier, I believe it is in their forecasting procedures to include POPs.

It's just my opinion, but while some people might like to hear POPs in their weather forecasts, I find them too general for most weather situations.

After a couple of chilly late-April days with winds off the lake, many of you would love to pave over the lake and cover up that cold water.  But that would only make it easier for an attack from the people of lower Michigan.

Seriously, that lake water temperature is cold in spring and any hint of a breeze from the direction of the water insures us of a chilly day.  Water has a huge heat capacity, which means it does a wonderful job of storing the heat from summer, but an equally good job of hanging on to the cold from winter.  Water is much slower to change temperature compared to land.

This week the mid-lake surface water temperature is around 39 degrees and the lakeshore surface water temperature is perhaps a degree or two warmer.  Daily temperature charts of the lake surface can be seen HERE.  The data is compiled from a satellite with a sensor that can measure surface water temperature remotely.  There are also buoys out on the lake with thermometers to directly measure the water temperature.

Monday and today (Tuesday) were also good examples of how chilling the air can get without help from the sun.  The late-April sunshine packs a pretty good punch and can provide some warmth.  Not the warmth of a high-in-the-sky mid-July sun, but still not bad.  The clouds over the past two days didn't help our efforts to warm the air.

High temperatures on Tuesday were a full 5 to 7 degrees colder than my forecast simply because I didn't factor in the lack of sunshine.  I was calling for nearly full sunshine.  But without it, our hope for warmth is....well, hopeless.

Ahhhh, but Lake Michigan provides us with such beauty, we wouldn't really want to cover it with a layer of concrete, would we?  The fish would hate us, Michiganites would invade our fair state, and eventually somebody would want to put up a shopping mall right about where the Milwaukee harbor breakwater is located.  No, I'll take the chill instead.

While we froze under a brisk northeast wind on Monday, the southwest U.S. sizzled once again.  It has been a hot and dry week for southern California, Arizona, New Mexico, southern Utah and southern Nevada with little relief in sight.  And while that may sound great to us here in the chilly Midwest, the residents of the west and southwest are bracing for another fierce fire season.

The southwest U.S. has been suffering under drought for nearly 10 years.  A fairly wet winter two years ago allowed a lot of brush to grow in the spring, and that made for adequate fuel to burn during the 2007 fire season.  Now conditions are setting up for yet another nasty season of flame, which can extend from now right into next autumn.

Winter is the time of year when the southwest, including southern California, gets the majority of their rainfall.  Huge wet weather systems come onshore in California and can drop a lot of rainfall on the west coast.  Mudslides are common in California, and sometimes flash flooding can occur in Arizona when too much rain falls in a short amount of time.  The hardpack of the desert acts like a concrete floor and moisture has a tough time getting absorbed into the ground.

Now the desert plants are blooming and the brush is getting lush - perfect fuel to burn.  Dewpoints out west are very dry and many counties are under "red flag" alerts for high fire danger.  Aggravating the problem in summer will be the "dry" thunderstorm.  These are storms like we get here in the Midwest, except with low-level air so dry, most of the raindrops evaporate before reaching the ground.  However, the deadly lightning bolts still reach the ground and can spark wildfires.

We have our share of weather problems here in Wisconsin, but we don't have to contend with the mudslides in winter and the wildfires in spring and summer.  It just proves there is no perfect place to live, and nature always has the final word.

I'll be the first to admit I have mixed emotions about people going out and chasing and photographing storms.  On the one hand, I love to see the cool pictures and video.  On the other, I realized most of them are non-meteorologists without proper knowledge of storm structure and are putting themselves at great risk.

As you probably know, storm chasing has become quite a sport these days.  The move "Twister" probably added many people to the storm chasing roster.  That movie, by the way, was so meteorologically inaccurate that it would take a long list to reveal all of the errors.  The scene with the cow flying by the window of the car comes to mind.  Bad science but good special effects.  By watching that movie, most people are convinced you can drive up alongside a vicious tornado without consequence.

In reality, you can't get that close to a real twister, even a small one.  But the special effects were outstanding and that's what Hollywood uses to put people in the seats of the movie theater.  It also got more and more people to take to their vehicles and crisscross the Plains of the United States in spring, searching for the elusive twister.

Storm chashing has also become quite a business.  Consider that there are a number of companies that will take you and up to a dozen other strangers across the fruited plain in a cramped van for a week searching for tornadoes.  There is Windswept Tours (http://www.chasetours.com/index.html) and Storm Chasing Adventure Tours (http://www.stormchasing.com/) to name just two.  Do a Google search of storm chasing tours and you'll get the idea.  Obviously, these tours can't guarantee you will see a tornado, but they will do everything they possibly can to get you close to one.  And that usually means a lot of driving, which is what storm chasers have to do.  Putting on 500 miles a day is not unheard of if that's what it takes to get to a developing squall line before sunset.

Technology has now partnered with storm chasing.  A new venture called Severe Studios  (http://www.severestudios.com/) is up and running and putting live streaming webcam video of storm chases on the internet.  Often the quality of the video is amazingly clear.  Wireless internet connections via cell phones make it possible to broadcast live from the road.  I'll admit its pretty cool stuff.

So if you are a fan of severe weather and want to live vicariously through storm chasers, check out the Severe Studios web site.  On a day when severe weather is popping in the central U.S., this will be one busy web site.  Who knows?  Perhaps one day we'll see storm chasing as an Olympic sport.

With the fire at St. Stephen Catholic Church on the south side of Milwaukee probably due to a lightning strike, it is appropriate that we wrap up our severe weather myth series of blogs on the topic of lightning.  At any one time there are about 2,000 to 3,000 thunderstorms in progress around the world and hundreds of thousands of lightning bolts.  Some of the bolts travel from cloud-to-cloud, others are intracloud (within the same cloud), and still others are cloud-to-ground.

Technically the initial lightning bolt travels upward, with subsequent flashes pulsating down to the ground.  The base of the cloud sends down a bunch of negative charges in a stepped leader.  This trail of electrons travels in steps of about 50 yards in length, with each step taking less than a millionth of a second.  The stepped leader is very fast and impossible for us to see.

As the stepped leader reaches down to the ground, a trail of positive charges moves upward to meet the negative charges.  These postive charges usually gather at the tip of a tall object.  Once the two trails connect, the path has been cleared for electrical current to run from ground to cloud and back again.

The bright return stroke then moves from cloud to ground in 100 millionth of a second.  This is what we traditionally think of as the lightning bolt.  Because it is so bright, its image is burned into our eye and we perceive it to last much longer than it really does.  So the stepped leader travels downward, meets the positive charges moving up from the ground.  Once the path is established, the visible return stroke heads back down again.  It's quite a process.

But are you safe if you are inside a car?  It depends on the car.  Here's the myth-buster: you are not safe because the rubber tires insulate you from the electrical current.  Rubber is a good insulator but so is air.  The lightning bolt just travelled through 1/2 to 1 mile of air to reach your car, so those measely little tires won't stop the surge.  You would need tires about a mile thick to protect you.

Often the tires of a car will melt if it is hit by lightning.  You are protected if the car is metal, all of the windows are closed, and you are not touching any metal objects inside the car.  If the car is hit by lightning, the electrical current will travel around the outside "skin" of the metal car.  Cars made of fiberglass or plastic, or cars that are convertibles, may not offer the proper protection.

Here are links to two You Tube videos that deal with cars being hit by lightning.

Link 1            Link 2

The first link is about 2 minutes long and is from a news report in Canada.  The second link is about 5 minutes long and is from a BBC television show.  Both are interesting, although the Canada report hints that the rubber tires saved the family inside the van.  That is incorrect.  The BBC report claims a car acts as a Faraday cage, but technically that is not true.  The occupants of a car are safe because of the "skin" effect of the automobile.

For a brief but technical explanation of the skin effect, go HERE.

Don't worry, there won't be a test on any of this.  :)  But the whole "rubber tires keeping you safe" myth is one that comes up time and time again.

Thursday, April 24, is the test day for Tornado and Severe Weather Awareness week.  At 1 p.m. there will be a test tornado watch issued for our area, and at 1:20 p.m. there will be a test tornado warning.  This is a great time to check out that weather radio you hopefully have in your house or office or school.

It is also a time that you might hear tornado sirens.  Just don't rely on them.  Don't get me wrong, the sirens are wonderful and are designed to alert people who are outdoors.  When you hear the siren then you know a tornado warning is in effect.  But you may not always hear the siren even if you are outside.  Why?  It depends on your distance to the siren and the direction of the wind.  Yes, a strong wind may carry that sound away from you if your distance to the siren is great enough.  Bottom line: don't wait to hear a siren.

So many times you will see news reports of people interviewed after a severe weather event.  So many times you hear them say "there was no warning", "I never heard the siren", etc.  Those reports drive meteorologists crazy.  There are virtually no severe weather events that go un-warned.  The National Weather Service does a great job of getting out the warnings in a timely manner, whether it be severe thunderstorm or tornado.

People say there was no warning because they have no way of hearing the warning.  They don't have a weather radio, they weren't listening to radio or TV, and they often rely on hearing the outdoor sirens when they are inside their house.

So in keeping with the theme of my blogs this week, here is another severe weather myth: listen for the outdoor siren so you'll know about weather warnings.  Myth!

In keeping with the theme of severe weather myths, here is one you have probably heard if you live in the western Great Lakes: you are safe from tornadoes if you live near Lake Michigan because the lake will protect you.  My parents used to tell me this as a little boy growing up in the suburbs of Chicago.  And they had good reason to say this to me: I was scared to death anytime a semi-dark cloud passed overhead.  I would run and hide under the bed when a few raindrops hit the house!

My parents were just trying to reassure me of my safety, but meteorologically speaking they were incorrect.  Lake Michigan is a large and chilly body of water.  Somehow that cold pool of air associated with the lake will scare away tornadoes.  In reality, its not true.  Thunderstorms approach us from the west and the lake is to our east.

We only need to go back to March 8, 2000, when a tornado struck St. Francis and Cudahy, touching down at the northeast corner of Mitchell Int'l. Airport at 6:14pm.  One of the deadliest tornadoes on record for Wisconsin occured on  May 18, 1883 when a twister struck the north side of Racine.  Twenty-five people where killed and 100 injured.  (Obviously the weather warning process wasn't in place in the late 1880s like it is today, but Lake Michigan did nothing to protect those people.)

I have seen cases where thunderstorms got weaker as they approached Lake Michigan.  I'm supposing this is due to a cool inflow of air from in front of the storm helping to weaken it a bit.  But I have also seen cases where an incoming thunderstorm interacts with a cool east wind that is part of a lake breeze.  The low-level wind shear created by the thunderstorm colliding with the lake breeze has caused small twisters to spin-up from the ground and cause damage.  These spin-up twisters are typically rather weak but they still have the potential to cause damage and injury.

With a strong supercell rotating thunderstorm, the most powerful beast in the thunderstorm arsenal, even Lake Michigan's flow of cool air will not prevent it from producing a tornado.  The lake provides us with many things, but protection from tornadoes is not one of them.