Snow Totals For Sudbury Rise As Nor'easter Approaches

SUDBURY, MA — We've known a storm is coming since early this week, but its exact impact have been difficult to pin down.

What we do know: there will be a lot of snow — more in some parts of the state than others — and the potential for some damaging winds. Here's what to know about the storm coming this weekend.

Timing

The snow will roll into the area sometime after 11 p.m. Friday, but won't really start accumulating until after midnight, according to forecasts. It could snow all day Saturday and into the early morning hours on Sunday.

Snow

The National Weather Service is predicting 12 to 18 inches in a wide swath between Worcester and I-95. That's a bit higher than earlier on Thursday when the weather service was predicting up to 12 inches in about that same area. The highly-regarded ECMWF forecasting model — known as the European model — is seeing just under 15 inches at the Worcester-Middlesex County border.

Southeastern Massachusetts could see much higher totals — perhaps as much as 22 inches.

Wind

The nor'easter will bring strong wind gusts starting Friday evening. Gusts could hit between 35 and 40 mph between Route 128 and Worcester, with slightly lower gusts farther west.

Is this bombogenesis?

Bombogenesis, or bomb cyclone, means a winter storm that almost looks like a hurricane.

"Bombogenesis, a popular term used by meteorologists, occurs when a midlatitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours," according to the National Oceanic and Atmospheric Administration

"A millibar measures atmospheric pressure. This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengthening weather system is a process called bombogenesis, which creates what is known as a bomb cyclone."

It's a fun word, but bomb cyclone systems are common, and this storm will like drop well below 24 millibars over 24 hours, according to forecasters.