As you may have learned from Twitter, or your phone, or just by paying vague attention to nearly any news organization: a big storm is headed for the northeast, bringing as many as 20 inches of snow to New York and more to New England. What do we know? What do you need to know?

It's going to start tomorrow morning...

So far the forecast is for a light snow starting early tomorrow morning, possibly mingling with rain as temperatures rise later in the day. By mid-afternoon expect 4-6 Facebook posts complaining that the snowstorm is a letdown, increasing throughout the day.

...but won't really kick in until tomorrow night.

Temperatures are going to drop quickly, and that's when the snow will really start. In New York City it should end by Saturday morning; in New England, it'll continue through Saturday. By Monday government will have disbanded, and roving gangs of vicious post-humans on snowmobiles will patrol neighborhoods demanding tribute.

It's actually two different storms combining.

The worst case scenario that everyone is preparing for involves two storms, an Alberta Clipper (hailing from Alberta to the northwest) and a southern storm heading northward, merging quickly tomorrow.

It could be the biggest snowstorm in a century.

New York City could get anywhere from 10 and 20 inches; Long Island could get 18 inches; Boston could break its record of 27 inches; if all these forecasts are true, we're looking at a record-breaking haul of measurement-based dick jokes across the Northeast.

It's going to be windy.

We could get 50 m.p.h. winds here in New York. Talk about a "Windy City," ha ha, but don't get hit by a falling telephone pole, please.

You are probably not getting anywhere in the Northeast this weekend.

More than 500 flights have already been canceled, and Amtrak is going to suspend service between Boston and New York sometime tomorrow.

It's not really named "Nemo."

The only people calling this story "Nemo" work for the Weather Channel, which decided last year that it would start to name winter storms the same way the World Meteorological Organization names hurricanes. Many people and organizations—the National Weather Service, for example—object to this: there aren't really strict guidelines governing what kinds of storms receive names and what kids don't, and unlike hurricanes—which have an identifiable center and clear direction—winter storm systems are erratic and complicated. (There are also, yes, commercial considerations here.)

Worse, the Weather Channel is giving winter storms terrible, pandering fantasy-novel names like "Draco," "Gandolf" and... "Nemo." For this reason we suggest using your own name for the storm, like "Snowlo" or "Flake-Quake" or "The Big Snow Storm."

THUNDERSNOW!

The Wall Street Journal's Eric Holthaus gets it: "Thundersnow - that rarest and most exciting of weather phenomena - could again grace the skies above New York City on Friday night."