Storms that receive the type A classification develop primarily in the Gulf of Mexico or along the southern East Coast, near Georgia and South Carolina. These storms develop primarily on the Gulf Coast or East Coast along a decaying cold front, or along the marine/land air mass contrast found on the East Coast. Miller A systems then quickly deepen and intensify as they move northeastward. Type A storms typically move rapidly, hitting the Mid-Atlantic United States the hardest. Nevertheless, New England can still receive significant snow depending on the system's intensity. The Superstorm of 1993 is considered to have been a Miller Type-A storm.

Storms that receive the type B classification develop inland over the United States. Storms that come in from the west (up the Ohio Valley) are usually referred to as "Miller Type-B" storms. These storms originate as an area of low pressure creating storming weather over the Midwestern United States and the Ohio River Valley. These storms have a defined low-level circulation center that moves toward the Appalachian Mountains from the west. As these storms approach the mountains, they lose their defined circulation center due to high terrain. A more powerful cyclone spins up along the warm Gulf Stream waters off the coast of North Carolina. When this re-development occurs, the storm produces precipitation, including heavy snow, along the inland parts of the Mid-Atlantic. After redevelopment, the nor'easter takes a northerly track, then turns out to sea near New England. An example of this storm is the February 5–6, 2010 North American blizzard.