DEEP: Coastal Hazards Primer - Winter Storms

Coastal Hazards Primer - Winter Storms
 
Coastal Hazards Primer
 Introduction   Precipitation
 Flooding    Tropical Storms and Hurricanes 
 Erosion   Winter Storms 
  Wind  
 
Winter storms, aka "Nor'easters," can produce high winds, storm surges, and massive amounts of precipitation.  The official definition of a "Nor'easter" is a strong low pressure system that affects the Mid-Atlantic and New England states. These winter events are notorious for producing heavy snow, rain, and tremendous waves that crash onto beaches, often causing beach erosion and structural damage. Wind gusts can exceed hurricane force in intensity. A nor'easter gets its name from the continuously strong northeasterly winds blowing in from the ocean ahead of the storm and over the coastal areas. What makes them so strong is the warm and moist air from the Atlantic that feeds the storm, causing it to grow explosively.29

According to the The Connecticut Natural Hazard Mitigation Plan (NHMP), moderate to severe coastal flooding occurs when the following three criteria are met:

  • Winds greater than 30 mph lasting more than 12 hours.
  • Wind direction in a range from the northeast to the east-southeast. 
  • Astronomical high tides.

The last winter storm to meet these criteria occurred December 10-13, 1992.  This storm produced continuous east/northeast winds up to 55 mph.  As a result, Bridgeport, CT recorded a high tide of 10.16 ft NGVD, the third highest recorded in Long Island Sound.  This storm destroyed 26 homes and killed three people.  

Perhaps the most famous winter storm in history is the so-called "Storm of the Century" which impacted the entire east coast of the US March 12-15, 1993. This catastrophic event produced record snowfalls from the northeast to the Florida panhandle. In total, the storm killed 270 people, with another 48 lost or missing at sea, and totaled in excess of $6 billion dollars of damage.30

Since they strike Connecticut frequently, strong winter storms cumulatively cause more coastal flooding, erosion, and annual damage to property than do hurricanes.  Major winter storms have struck Connecticut in 1979, 1983, 1992, 1993, 1996, 2003, and 2007. While these storms were notable for their intensity, serious beach erosion is also caused by smaller winter storms which can often occur in rapid succession. 

In addition to flooding, frozen precipitation is a unique hazard associated with winter storms.  All forms of wintry precipitation, such as sleet, freezing rain, snow, and hail can create hazardous conditions on roads and walkways, and damage infrastructure like power lines, buildings and trees from the weight of ice of snow. 

Ice related events are rare in Connecticut, and even more so along the coast where the waters of Long Island Sound create a warmer winter climate than highland areas of the state.  Nevertheless, under the right meteorological conditions, they are possible given the topography and hydrology of the area. Ice storms require temperatures below 28°F for at least 12 hours and at least ˝ inch of rain.  Ice jams are an accumulation of ice in a river that restricts water flow and may cause backwater that floods low-lying areas upstream from the jam. Areas below the ice jam can also be affected when the jam releases, sending water and ice downstream

For more information about winter storms, including how they form and explanations of sleet, snow, freezing-rain, etc., visit the NOAA's National Severe Storms Laboratory page on Winter Weather Basics.

In Summary
What can you do when it comes to the threat of winter storm events in Connecticut?

 
Content Last Updated January 3, 2012