>>> AT LEAST TWO BRIEF TORNADOES TOUCHED DOWN IN CHICAGO IN THE SUBURBS TODAY, ONE IN JOLIET AND ONE IN NAPERVILLE.

TWO OTHERS WERE SPOTTED WEST OF CHAMPAIGN FORCING MANY TO TAKE SHELTER.

HOW COMMON ARE TORNADOES IN WINTER MONTHS?

WE CAN PROVIDE SOME CONTEXT.

PAUL, GOOD TO TALK TO YOU.

AS ALWAYS WE MENTIONED THESE TWO BRIEF TOUCHDOWNS IN NAPERVILLE AND JOLIET, WHAT DO WE KNOW ABOUT THESE?

>> IT WAS KIND OF A SURPRISE THIS MORNING, THEY FORMED PRETTY RAPIDLY , FOR A SHORT PERIOD OF TIME.

THE ATMOSPHERIC WAS JUST PERFECT .

A LITTLE BIT OF WARM AIR CAME UP FROM CENTRAL ILLINOIS AND THAT LITTLE AREA WITH A LOT OF VERTICAL WIND SHEAR, IS REALLY WHAT LED TO SOME BRIEF TORNADOES.

>> DID WE SEE ANY SIGNIFICANT DAMAGE OR INJURY?

>> I HAVEN'T HEARD OF ANY SIGNIFICANT DAMAGE, A FEW TREES FELL, I DID GO OUT TO THE NAPERVILLE AREA, THERE'S A LOT OF TREES IN THAT REGION NEAR A FOREST PRESERVE.

THERE'S A BUNCH OF TREES THAT ARE ALREADY DOWN SO IT'S HARD TO FIND OUT WHAT HAD BEEN DAMAGED.

VERSUS WHAT HAD BEEN DAMAGED IN THE PAST.

THERE WAS A COUPLE OF SIGNS ESPECIALLY NEAR AN OVERPASS WHERE A TREE LOOKED LIKE IT HAD TIPPED OVER.

SO SOME OF THOSE THINGS WERE DAMAGED BUT NO REPORTS OF SIGNIFICANT STRUCTURAL DAMAGE ANYWHERE.

>> WE ARE LOOKING AT VIDEO OF ONE OF THOSE FUNNELS.

HOW RARE IS IT TO SEE THIS IN FEBRUARY?

>> YOU KNOW, WHEN YOU HAVE A COLD SEASON TORNADOES SUCH AS DECEMBER THROUGH FEBRUARY, IN THE WINTER MONTHS, ANYTIME WE GET THAT WARM MOIST AIR WE ALWAYS HAVE THE CHANCE FOR TORNADOES BECAUSE IT'S USUALLY ASSOCIATED WITH VERY STRONG WIND.

SO IT IS A DYNAMIC SYSTEM AS OPPOSED TO ONE THAT MAY COME FROM HEATING FROM THE SUN.

SO THE WIND WAS VERY STRONG AT ALL LEVELS OF THE ATMOSPHERE AND WHEN YOU HAVE SOME SUSTAINED STORMS, YOU CAN SPEND UP A BRIEF, ALBEIT WEAK TORNADO.

>> YOU ARE PRETTY CLOSE TO THE NAPERVILLE AREA.

YOU HAD TO TAKE SHELTER THIS MORNING, WHAT WAS THAT EXPERIENCE LIKE?

>> IT REALLY SURPRISED ME.

IT WAS RIGHT AFTER ONE OF MY CLASSES SOMEBODY SAID THERE'S A TORNADO WARNING OF THE SIRENS STARTED GOING OFF.

WE HAVE A PROGRAM IN PLACE TO MAKE SURE EVERYBODY GOES TO SHELTER SO, WHILE EVERYONE ELSE WAS RUNNING FOR SHELTER I'M OF COURSE RUNNING OUTSIDE TO OBSERVE WHAT'S GOING ON.

THE ONE THAT WAS FURTHER TO THE SOUTH WASN'T REALLY DOING MUCH BUT OUR AREA WAS STILL UNDER THE WARNING.

THERE WAS SOME RAPID VERTICAL MOTION, SORT OF THE PRECURSOR TO A TORNADO, RIGHT OVER THE COLLEGE.

ONCE THAT MOVED TO THE NORTH WE GAVE THE ALL CLEAR, THEN IT SHORTLY DISSIPATED.

>> YOU MENTIONED THE WARM AIR COMING IN FROM THE SOUTH AND UNSTABLE ENVIRONMENT, WHAT DOES IT TAKE FOR A TORNADO TO GAIN STRENGTH AS AND PERHAPS DO MORE DAMAGE?

>> USUALLY WE THINK OF TORNADOES IN THE SPRING, COMING UP APRIL THROUGH JUNE, THAT'S OUR PRIVATE MONTHS FOR STRONGER TORNADOES.

WARM AIR AT LOW LEVELS WITH HIGHER UP IN THE ATMOSPHERE, YOU'VE GOT VERY COLD AIR.

THAT'S WHAT LEADS TO A CONDITION WE CALL INSTABILITY.

THOSE ARE THE BIG THUNDERSTORMS, THERE'S A LOT OF LIGHTNING AND WIND AND MAYBE SOME HAIL ASSOCIATED.

WHEN THE WINDS CHANGE DIRECTION AS YOU GO HIGHER, THAT WILL LEAD TO THE DEVELOPMENT OF ROTATION WITHIN THE WHOLE STORM.

>> THIS SYSTEM WAS LIMITED ON THE AMOUNT OF INSTABILITY.

THERE WAS JUST ENOUGH TO GET THE ONSET OF THIS THING BUT IT FORMED ALONG THESE LITTLE BOUNDARIES.

THAT REALLY HELPS CREATE AN ADDITIONAL AMOUNT OF ROTATION IN THE ATMOSPHERE THAT GETS STRETCHED AS THESE THUNDERSTORM UPDRAFTS, KIND OF LIKE A FIGURE SKATER PULLING IN HER ARMS AND SPINNING FASTER.

THAT'S WHAT'S GOING ON WITH THESE THINGS.

SO THEY ARE NOT GOING TO BE THE STRONGER VIOLENT TORNADOES BUT THEY CAN DO DAMAGE AND THEY CERTAINLY HAVE THE ABILITY TO KNOCK OVER SOME TREES OR KNOCKED OVER BIG BRANCHES.

>> THAT'S A GREAT ANALOGY THERE WITH THE FIGURE SKATER.

WHILE I HAVE YOU PAUL, I THINK WE NEED TO PUT SOMETHING TO REST, THOSE OF US IN CHICAGO HAVE HEARD THIS RUMOR OR THIS NOTION THAT TORNADOES DON'T REALLY EVER HAPPENED WITHIN THE CITY LIMITS BECAUSE THE LAKE ACTS AS A MODERATING INFLUENCE, WHAT'S THE TRUTH?

>> THAT'S NOT REALLY A TRUE STATEMENT.

IF YOU LOOK AT THE HISTORY OF TORNADOES, AND YOU CAN GO AS FAR BACK AS 1967 WITH THE TORNADO THAT WENT INTO THE LAKE ON THE SOUTH SIDE OF THE CITY.

OR YOU CAN LOOK AT OTHER TORNADOES THAT HAVE CUT ACROSS.

THE LAKE, ALTHOUGH IT MODIFIES AND CERTAINLY AFFECTS OUR WEATHER, IT DOESN'T ALWAYS GIVE THAT PROTECTION TO THE CITY.

ANYTIME THE WIND IS SOUTHERLY OR SOUTHWESTERLY YOU STILL GET THAT.

I THINK IT WAS TWO YEARS AGO WE WERE VERY CLOSE TO A PRETTY SIGNIFICANT EVENT, A STRONG THUNDERSTORM MOVED ACROSS THE CHICAGO PROPER FOOTPRINT OF THE CITY.

WITH THAT ONE DID NOT PRODUCE A TORNADO, SO PRETTY MUCH IT'S A MATTER OF TIME, IT COULD BE FIVE YEARS, IT COULD BE 100 YEARS, BUT CHICAGO WILL BE HIT BY TORNADOES.

>> LET'S HOPE NOT ANYTIME SOON ALTHOUGH I DO REMEMBER SOME