Wednesday, December 19, 2012

Weather Whys Wednesday: Categorizing Winter Storms


With a more active winter storm pattern upcoming nationally, let's talk a bit about how winter storms are classified, not by name or numeric category, but by type. More sophisticated weather weenies already know most of this, but you may have stumbled upon these terms and wondered what people were talking about.

A great primer on types of winter storms and impacts (though focused on the Carolinas) can be found here.

 Generic Miller A Storm Track; Credit: NOAA
Miller A: These are usually some of the bigger storms that you'll see, though not necessarily the biggest snow producers in the Delaware Valley. Normally, the low will develop in the Gulf of Mexico, intensify rapidly and shoot up the Eastern Seaboard. Sometimes it tracks a bit inland, and other times it tracks a bit offshore. The 1993 Storm of the Century is a good example of a Miller A type storm. Also, the Blizzards of 1996 and 1983 were Miller A's.

Generic Miller B Storm Track: Credit: NOAA
Miller B: These are usually more complex, as there's a two-part process involved. First, the storm will move through the Midwest, often producing snow in places like Ohio, Indiana, or Michigan. As it approaches the Appalachian mountains, that area of low pressure will lose definition, while at the same time, a new, stronger low develops off the Carolina coast. That low will be a typical nor'easter in most cases, ride up the coast offshore, and generally produce heavy snow for parts of the area. President's Day 2003 was an example of a Miller B.

Alberta Clipper: This is when a storm develops in the Canadian prairie region. The storm will dip south and then get pushed along by the faster jet stream to the south and east. Alberta clippers are quick moving, occasionally moisture starved, and usually produce minor amounts of snow. Clippers don't always bomb out and transition to Miller B storms. Often they will just innocently shoot offshore and not produce more than a few inches of snowfall. Depending on where the storm develops in Canada, it can also be referred to as a Manitoba Mauler or a Saskatchewan Screamer.

On the Plains, there's also a commonly referred to winter storm called a Panhandle Hooker, which develops in the Southwest, then hooks across the Texas and Oklahoma Panhandles and through the Plains and Upper Midwest, often producing blizzard conditions in the Plains and severe weather on the warm side. These can often produce prolific warm ups in front of them in the Delaware Valley.