quote:A classic late-season nor’easter has all the ingredients to produce what could be near-record-heavy March snow and dangerously strong winds in coastal cities from Washington, D.C., to Boston. But if the devil were ever in the details, it’s right now. The dividing line between rain and snow in this storm, dubbed Stella by The Weather Channel, will be close enough to the Interstate 95 corridor to keep forecasters sweating. Right now it appears that the meteorological bounty will be mainly in the form of snow for the big East Coast cities. However, just a minor shift in track could bring rain or sleet into the metropolitan areas, at least for a brief period.There’s no doubt that a big storm is in the cards. Upper-level energy from two sources—a large trough swinging across the Midwest and a upper-level wave at the base of this trough over the Southern Plains—will be joining forces along the East Coast by Tuesday. The interplay between these two factors is just one of the elements of uncertainty on the table.What’s clear is that a surface low off the central Gulf Coast on Monday morning will begin to strengthen near the Outer Banks Monday night, then rapidly intensify as it moves northeast along and/or just off the East Coast through the day on Tuesday. As shown in Figure 1 below, the 12Z Monday run of the GFS model deepens the low 23 millibars in 24 hours, from 2:00 am EDT Tuesday to 2:00 am Wednesday, as it moves from near Cape Hatteras, NC (1000 mb), to the central coast of Maine (977 mb). This would bring the low very close to the official definition of a meteorological “bomb”—a midlatitude low that deepens at least 24 millibars in 24 hours.