Typical weather patterns in the New England states during late October and November are conducive to the formation of massive storms. At this time of year, large cold air masses from Canada cross the midwestern states on a regular basis. At the same time, the Atlantic Ocean retains its summer heat and these warm waters sometimes spawn hurricanes. When the east-moving cold air masses encounter the warm, humid oceanic air, the result is what New Englanders call Nor'easters: storms that are often severe and often the cause of maritime disasters.
The Gale of 1898 (also called the Portland Gale) began as three air masses: an area of high pressure over the Ohio valley, a weak low-pressure area near Minnesota and another low over the western Gulf of Mexico. By the evening of November 24, the high pressure area and Great Lakes low had both moved eastward. With the counterclockwise (cyclonic) circulation typical of air masses in the northern hemisphere, the Great Lakes low drew in Arctic air from Central Canada, lowering temperatures dramatically across the northern plains. To the south, the Gulf of Mexico low was spreading rain across the southern states from Louisiana to Georgia.
By the morning of November 26, the high pressure area was off the New England coast, the Great Lakes low was centered over Detroit and the southern low was just off the coast of South Carolina. At this point, the two low-pressure air masses were connected by an elongated area of low pressure known as a trough, which facilitated energy exchange between the air masses. As the Great Lakes low continued its eastward advance, the southern low began to move up the east coast, gradually gaining strength and speed. By 3:00 p.m., the southern low had almost completely absorbed the Great Lakes system and was spinning off Norfolk. As the weather system continued to grow, large amounts of moisture absorbed from the Gulf Stream became a massive snowfall that extended from Washington, DC to New York City.
As the storm moved north, a steep pressure gradient developed between the low pressure storm system and the areas of high pressure to the northeast, as well as between the storm system and the Arctic high to the northwest of the storm. The result was unusually strong gales that bettered central and southern New England for the entire day on November 27. By Monday, November 28, the storm had moved off to the northeast, leaving below-freezing temperatures, a devastated coastline and shocked communities that only gradually learned of the Portland's fate.
Reference: Oceanexplorer.noaa.gov
