Meteorologists generally split major winter storms into two types: ?A? and ?B,? specifically ?Miller ?A? and ?B?. The ?A? is the ?easiest,? forming in or near the Gulf of Mexico and then moving up the East Coast as a nor?easter. The Blizzard of ?96, our biggest snowstorm, was a perfect example. We can be pretty sure a couple of days in advance that a major winter storm is coming. The tough part with these is often telling where rain vs. snow will fall. THIS ONE IS NOT A MILLER A.
The Miller B often starts as a harmless ?Clipper? -- the ones that come from Canada and race toward us. Once-in-a-while, the low pressure center will move just offshore and strengthen A LOT (you may have heard the term ?bombogenesis? -- this is it).
The rapidly falling pressure ?
increases the winds, moving more moisture onshore
increases upward motion, leading to heavier precipitation
slows the storm down, leading to a much longer period of snow
sets up ?bands? of snow, where a narrow strip gets clobbered, while nearby areas get much less
?B? storms are toughest to forecast because we?re dealing with a storm that develops. The exact location where it develops and strengthens is crucial. A ?miss? by even 50 miles can lead to HUGE differences in how much snow will fall in some areas. The toughest part is on the southern edge of the snow area, where even a 20-mile difference can have, for example, only a couple of inches vs. one foot or more.