GEOFF BENNETT: A sprawling and# potentially devastating winter## storm is projected to slam a massive# swathe of the country tomorrow and## through the weekend from New Mexico# all the way to Northern Maine.

Heavy snow, life-threatening cold and dangerous# ice accumulation are all in the forecast.

More## than 130 million people are currently under# winter storm alerts, and nearly every American## east of the Rockies will be affected.

That's# according to the National Weather Service.

To help break down what we expect# to see and how you can prepare,## we're joined now by MyRadar senior# meteorologist Matthew Cappucci.

Thanks for coming in.

MATTHEW CAPPUCCI, Senior## Meteorologist, MyRadar: Yes, good.. I have to say, the scale of th.. is matched only by its intensity.

I mean,## the fact that we have roughly 1,800 miles# nonstop of winter storm alerts, watches,## warnings from Arizona all the way to the# East Coast shows just how big this storm is.

It's getting going right now off the# U.S.

West Coast.

That's an upper-level## pocket of cold air or low pressure# and spin, this big swirly twirl on## the water vapor satellite.

It's kind of# the impetus for the storm system.

But you## will notice it's still offshore.

So we# can't launch weather balloons into it.

And so actually last night the hurricane# hunters, those folks who fly into hurricanes,## flew into this storm to collect data to help us# figure out what this thing's going to do.

We pump## that into models.

And you can see just an absolute# mess on the simulated radar, rain, snow, sleet,## freezing rain, the worst of everything from New# Mexico, Texas all the way to Southern New England.

GEOFF BENNETT: What does the forecast say about# snowfall?

Where do we expect to see the most?

MATTHEW CAPPUCCI: So I think the# snow jackpot should be in roughly## a 50-to-100-mile-wide zone north of the# rain/snow line.

It starts near Oklahoma City,## pushes northeast all the way towards# D.C., Baltimore, Philly, New York City.

All those places have a roughly 50/50# shot of seeing a foot or more of snow,## Tulsa probably 12 to 18 inches.

Then# Southern Missouri, the Bootheel,## Western Kentucky along the Ohio River, that's# where the worst will be.

But in addition to that,## on the southern side.

It's not just the snow.# It's the sleet and the freezing rain too.

GEOFF BENNETT: And what about the life-threatening# cold?

There's also threats of ice accumulation.

MATTHEW CAPPUCCI: Yes, the ice accumulation# is really what worries me the most,## because for folks at home, ice happens when you# have rain that essentially falls as a liquid## and then turns into ice on the ground,# given sub freezing surface temperatures.

In that freezing rain zone,# temperatures might be in the## mid-40s a mile above the ground.# So liquid rain is going to fall,## but the surface might be 25, 30 degrees.# So all that liquid freezes on the ground.

Two main areas.

I'm really watching for the worst# ice accretion, I think Northwestern Mississippi,## Northeast Louisiana, probably south# of Memphis along Interstate 55,## that's the zone I'm really# watching for potentially## significant ice accretion.

We're talking# like a half-inch to an inch in spots.

And it only takes about a -inch of# ice to pull down the power lines,## get power outages, the roads impassable# probably from Friday night all the way## through Monday morning.

And then behind# it, of course, the cold comes in.

The other zone I'm really watching, northeast of# Atlanta into for example the Western Carolinas,## Asheville, Greensboro, Spartanburg, Greenville.# I'm really worried that cold air at the surface## draining down the Appalachians will# keep the surface subfreezing even when## it's warmer upstairs, so again serious ice# accretions possible northeast of Atlanta.

And I wouldn't even be surprised for some thunder# sleet and thunder ice to mix in too, thunder... GEOFF BENNETT: Thunder ice.

MATTHEW CAPPUCCI: Thunder,# lightning,.. GEOFF BENNETT: All right, Matthew, so# two questions.

What are the dangers## of this type of weather and what# should people be doing to prepare?

MATTHEW CAPPUCCI: You know, I'm really concerned# about both the snow and the ice, especially,## because, snow, you can pre-treat.

You# can put stuff down in the roadways.

Ice comes down as a liquid and it washes# away any pretreatment.

So I think it's## going to be like a skating rink for a lot# of people until the middle of next week.

And the worst part, given these cold# temperatures invading, there's nothing## to really melt this until the end of next# week.

Look at temperatures early Monday## morning.

We're talking negative double digits# over the Upper Midwest, the Northern Tier,## excessive cold warnings in effect for a wide# area from really Minnesota down to Oklahoma City,## single digits, below zero, Little Rock, Oklahoma# City, single digits above zero in Texas.

And given how much ice is coming down, I think# a lot of folks will likely lose power too.## So you have systematic -- the issues with# vulnerability.

You're going into a cold air## outbreak with a lot of people who won't# have power.

I'm very worried about that.

So, given the forecast, I'd say bundle up.# Make sure you have everything you need for## about three to five days off the grid.# Make sure you're taking care of elderly,## vulnerable neighbors, loved ones, and ultimately# having a plan to hunker down for days on end.

GEOFF BENNETT: That is good advice.

Matthew Cappucci, our thanks to you, a.. MATTHEW CAPPUCCI: Thank you.