Ocean-Effect Snow: What You Need To Know About The Weather Phenomenon (And Should You Be Concerned?)

Many Americans are familiar with the term lake-effect snow. Those who live in the Great Lakes Region, the area most often impacted by this winter weather occurrence, certainly know how it can affect their area. However, with winter weather on the way, it may come as a surprise to some that a similar weather experience happens in some coastal areas. Known as ocean-effect snow, this weather phenomenon is essentially the saltwater sister of lake-effect snow and forms in the same manner. Like the inland version, ocean-effect snow can be problematic in certain situations and locations.

The basic idea behind ocean-effect snow, which is sometimes called sea-effect snow, is somewhat simple. When very cold air moves across large bodies of water that are warmer than the air above it, the slowly warmed air will rise from the water, be cooled, and form snow. The snow can fall at sea or, if the wind is blowing towards a land mass, over land.

However, in order for the snow to form, a variety of factors must be aligned, from the air temperature to the condition of the water's surface. When this confluence of conditions is just right, heavy snow is possible, but because the right conditions often come together in relatively small areas, ocean-effect snow can be difficult to predict.

If you are wondering whether you should be concerned about ocean-effect snow, it really depends on a few factors. The main aspect is location. Ocean-effect snow can theoretically occur in any gulf, ocean, or sea that may have a sudden cold blast of air cross over it. However, this weather phenomenon only commonly happens in a handful of areas around the world. The best known of these is Japan. There, ocean-effect snow is so frequent that it is one of the main reasons why the northwest portion of Japan averages more snow than anywhere else in the world.

In the United States, ocean-effect snow most often happens along the northeast coast and the Mid-Atlantic region. In rare events, it has also happened in areas of the Gulf Coast and Southeast U.S., although the air there is typically not cold enough. When the conditions align for ocean-effect snow to occur in these areas, an impressive amount of snowfall can be produced in a short period of time.

Timing is another major factor for ocean-effect snow to form, since the water still needs to be warm when the cold air arrives. This is much more common when an early-season polar vortex or cold front pushes through before the water has chilled. This can also happen when isolated cold air systems move through during a warmer-than-usual winter season. However, most ocean water temperatures remain warm enough for this to occur throughout the winter. If you live in or are visiting one of these areas during an ocean-effect snow event, it can cause significant problems, particularly with travel conditions, so stay safe.