Coastal Hazards Primer - Wind
Wind can be hazardous in several ways. Very high winds associated with storm events can directly damage structures by destroying roofs, windows, doors, etc; they can blow trees into structures and roadways, and destroy utility infrastructure. Strong winds can also pick up debris or loose materials and propel them, subsequently damaging property.
Even normal wind patterns can contribute to coastal hazards. Wind generates surface waves which cause erosion and transport of shoreline materials. Strong onshore winds also contribute to storm surge by means of wind set-up. In addition, wind can cause the movement of sand or other loosely consolidated, fine-grained materials onto and off beaches and dunes.
Below are the definitions of several damaging wind events that can affect Connecticut, courtesy of the NOAA National Severe Storms Laboratory:
Straight Line Winds: Any thunderstorm wind not associated with rotation, and is used mainly to differentiate from tornadic winds.
Downdrafts: A small-scale column of air that rapidly sinks toward the ground.
Downbursts: A strong downdraft larger than 2.5 miles across resulting in an outward burst or damaging winds on or near the ground.
Microbursts: A small concentrated downburst. Microbursts are generally small (less than 2.5 miles across) and short-lived, lasting only 5-10 minutes, with maximum windspeeds up to 168 mph.
Gust Front: The leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm.
Wind Data for Connecticut
Included in the previously mentioned Planning Report #29 are wind roses constructed from data recorded at the Bridgeport Airport from 1951 to 1970. These reflect the representative wind patterns for the coast of Connecticut, with the exception of the central coastal area around New Haven. In general:
- Spring (March – May) winds tend to shift from the winter northwesterly flow to the summer southwesterly flow.
- Summer (June- August) winds from the southwest prevail at approximately 8 – 18 mph;
- Fall (September – November) winds tend to shift from the summer southwesterly flow to the winter northwesterly flow.
- Winter (December – February) winds from the northwest prevail at greater velocities, often in excess of approximately 38 mph;
- In late winter and early spring, when winter storms are most likely, the wind roses indicates a significant component of strong winds from the east;
- The region of the central coastline around New Haven is more unique than other coastal areas. Here, wind direction typically takes a dominant north-south directional flow because of the funneling effect of Connecticut's central valley.
Planning Report #29 also provides tables summarizing wind data from United States Weather Bureau observations at New York City, Block Island, RI and New Haven, CT for the periods 1921-1939, 1932-1942, and 1921-1942, respectively.
The Connecticut State Building Code Supplement (2005) contains a list of basic wind speeds for every municipality in the state. The speeds are based on a map produced by the American Society of Civil Engineers that shows the maximum wind speeds (3 second gust at 10 m above ground) that structures should be designed to withstand. The map is available in the 2005 FEMA Residential Coastal Construction Manual. The values for Connecticut are generally consistent, and range from about 90 mph in the northwest corner to about 120 mph in southeast corner.
What can you do when it comes to the threat of winter storm events in Connecticut?
Content Last Updated January 3, 2012