>>> A monster winter storm
ominously called a bomb cyclone
is blasting large parts of the
U.S., leaving millions of
Americans facing record low and
life-threatening temperatures
and triggering travel havoc at
one of the busiest times of the
year.
We're working all of the angles
of this story with CNN's Omar
Jiminez, heath Muntean,
meteorologist Derek van dam.
Omar Jiminez is in Chicago where
it looks like a winter
wonderland but I imagine it does
not feel that way.
>> Reporter: Yeah, honestly, you
absolutely nailed that.
It feels like anything but a
winter wonderland.
But it is something that many in
this part of the country are
used to.
We are in the middle of what was
a huge temperature drop over the
course of today where we started
in the 30s, approaching zero
now.
We're going to continue into the
negatives overnight according to
the national weather service
here.
And one of the factors that
officials here in the city are
urging people to consider is,
it's not just going to be about
snow.
It's going to be about a lot of
factors coming together, making
the roads a lot more dangerous
than people might be used to.
It's not just snow.
It's wind and cold as part of a
huge weather system descending
on the U.S. Days before
Christmas.
This week over 80% of the
country's population will see at
or below freezing temperatures.
Some places way below, like
Denver where the temperature
dropped nearly 40 degrees in
just an hour, hitting negative
15 by Thursday morning.
Or Wyoming where a state trooper
took this video, zero
visibility, temperatures 60
below zero.
Parts of midwest are doing what
they can to keep up.
One of the biggest concerns in a
winter system like this is the
roads.
And this dome is part of what it
takes in a city like Chicago.
You're looking at 50,000 tons of
salt inside that crews come in
and out of over the course of
the day to try and help keep
these roads somewhat manageable.
The city has about 400,000 tons
of salt and more than 300
vehicles in its arsenal to fight
back on this second official day
of winter.
>> The goal is to keep up with
it, but we're going to be
fighting that wind.
If you can have a conversation
with those young drivers, you
know, those first-time drivers,
kids coming home from college,
trying to get home, just have
that conversation with young
drivers because this is a little
different kind of event.
>> Reporter: Cold temperatures
and snow are nothing new to
places like Chicago,
Minneapolis, and Buffalo.
Some meteorologists are calling
this a once in a generation
event.
>> Reporter: Even Atlanta is
forecast to have windchill in
the negatives Friday.
>> Communities across the state
are about to see temperatures
that they haven't experienced in
a decade or more.
>> Reporter: The message is the
same, even for places used to
dealing with bad winters.
It's the combination of snow,
wind gusts up to 50 miles per
hour, and the demand to get home
for Christmas that could mean
disaster, especially on the
roads where aaa estimates the
majority of those traveling this
holiday week will be driving.
>> It's not like a snow day when
you're a kid.
It's dangerous and threatening.
Is they really a very serious
weather alert here.
>> Reporter: You can see the
snow falling, you can also see
me pretty well.
Overnight these winds are
expected to pick up, and the
fear is for officials that all
the snow you see on the ground
and lightly falling is going to
blow around in that wind and
bring visibility down almost to
zero.
>>> We have CNN aviation
correspondent heath Muntean,
also in Chicago at o'hare
international airport.
One of the country's busiest, of
course, and Pete, thousands of
flights have already been
canceled.
This is far from over.
>> Reporter: Just checked flight
aware.
2,300 cancelations in the U.S.
So far today.
7,900 flight delays.
25% of all flights canceled here
at Chicago o'hare.
Buffalo, Detroit, Orlando, salt
Lake City, the list just keeps
growing by the moment.
Denver tops the list right now
of airports with the most
cancelations.
Then it's here.
Then it is Chicago midway.
This is such a crucial airport
for connections, though.
That's why this is going to have
a nationwide ripple effect.
It's a huge hub for American
airlines.
It is the biggest hub for united
airlines.
I went behind the scenes at
united's network operations
center to see how they are
handling this.
They are trying to make it so
that passengers are being
rerouted through other
connecting airports.
They did try and tell passengers
to book early and change their
flights to earlier flights and
not depart today, as the snow
hits.
At least some passengers heeded
that advice.
>> We thought it would be best
to escape and get out a little
bit before to avoid the weather.
>> It's Chicago.
It's o'hare.
We're used to this.
>> It seems kind of crowded.
It's pretty intense.
But --
>> It's Christmas.
We came early enough to
hopefully make it.
And hopefully our plane will
take off today and we'll get out
and get to Orlando, see our
family.
>> Reporter: Airlines say
download their app, get up to
the moment information on your
flight, delays, get on a new
flight.
Things could get worse as days
go on.
1,900 flights canceled tomorrow.
The temperature expected to drop
to 3 degrees fahrenheit.
That's going to be tough for
travelers.
>> 3 degrees, yikes.
CNN meteorologist Derek van dam
is tracking this storm for us.
Dangerous, potentially deadly
weather.
Give us the latest here 'twas
the nightmare before Christmas,
right?
This is it in realtime.
Where Pete and Omar are located,
it was 25 degrees warmer at this
time yesterday.
Denver, 50 degrees warmer 24
hours ago.
This is dangerous cold.
National weather service using
the terminology
"Life-threatening."
If you are outside in these
types of conditions, the exposed
skin has the potential to have
frostbite within a matter of
minutes.
City by city-locations.
Let's talk about what's
happening along I-80.
National weather service
explicitly discussing some snow
squalls that are possible that
could bring visibility between a
quarter of a mile to zero.
This is downtown Chicago.
You saw Omar's live shot a
moment ago.
The arctic front has pressed