Extratropical storm surge
Encyclopedia
Less commonly publicized than the effects from tropical cyclones, Extratropical Storm Surge can be just as destructive, and much more frequent in certain coastal communities. For an overview of storm surge, please see the parent article
.
s pushing on the ocean
's surface create storm surge by causing the water to pile up higher than the ordinary sea level
. However, unlike most tropical cyclone storm surge, extratropical storms can cause higher water levels across a large area for longer periods of time, depending on the system. This is due to many factors, such as storm size and different steering winds, which could keep a system in a storm-surge prone area for longer periods of time.
Additionally, a common but frequently overlooked component of extratropical storm surge is the phenomenon of negative water levels. If strong winds are blowing offshore, situations can arise where mean water levels in a bay fall significantly, which poses a serious threat for ships tied up at piers. If negative water levels are severe enough, ships tied up at docks can actually sit on the seafloor, preventing them from leaving port.
Ocean Prediction Center
for the Pacific & Alaska coasts, and North of 31°N on the Atlantic Coast. The National Hurricane Center
, to a lesser extent, mentions extratropical storm surge for the Gulf coast states mostly during the wintertime, when extratropical cyclones affect the coast.
Meteorological development laboratory in Silver Spring MD has developed an extratropical storm surge model with different domains of US coastline. Similar to the SLOSH model, the ETSSM runs off of the GFS computer model, and can provide guidance on above or below average water levels in a certain geographical domain as the result of a storm system's influence. Its resolution however, is more coarse than most of the specific SLOSH domains because it covers regions as opposed to small-scale basins that can be affected by landfalling tropical cyclones.
developed into a Nor Easter off the Southeast US coast. During the event, storm force winds from the E were present along the northern periphery of the low pressure center for a number of days, forcing water into locations such as Chesapeake Bay. Water levels rose significantly, and remained as high as 8 feet above normal in numerous locations throughout the Chesapeake for a number of days as water was continually built-up inside the estuary from the onshore winds and freshwater rains flowing into the bay. In many locations, water levels were shy of records by only a tenth of a foot.
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
.
Mechanics
Similar to tropical cyclones, extratropical storms cause an offshore rise of water. High windWind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
s pushing on the ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
's surface create storm surge by causing the water to pile up higher than the ordinary sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
. However, unlike most tropical cyclone storm surge, extratropical storms can cause higher water levels across a large area for longer periods of time, depending on the system. This is due to many factors, such as storm size and different steering winds, which could keep a system in a storm-surge prone area for longer periods of time.
Additionally, a common but frequently overlooked component of extratropical storm surge is the phenomenon of negative water levels. If strong winds are blowing offshore, situations can arise where mean water levels in a bay fall significantly, which poses a serious threat for ships tied up at piers. If negative water levels are severe enough, ships tied up at docks can actually sit on the seafloor, preventing them from leaving port.
Prediction
Extratropical storm surge, although not a common event in some basins, especially on the US East Coast, is mentioned in guidance from the National Weather ServiceNational Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
Ocean Prediction Center
Ocean Prediction Center
The Ocean Prediction Center , established in 1995, is one of the National Centers for Environmental Prediction’s original six service centers. Until January 12, 2003, the name of the organization was the Marine Prediction Center. Its origins are traced back to the sinking of the RMS Titanic in...
for the Pacific & Alaska coasts, and North of 31°N on the Atlantic Coast. The National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
, to a lesser extent, mentions extratropical storm surge for the Gulf coast states mostly during the wintertime, when extratropical cyclones affect the coast.
Extratropical Storm Surge Model
The National Weather ServiceNational Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
Meteorological development laboratory in Silver Spring MD has developed an extratropical storm surge model with different domains of US coastline. Similar to the SLOSH model, the ETSSM runs off of the GFS computer model, and can provide guidance on above or below average water levels in a certain geographical domain as the result of a storm system's influence. Its resolution however, is more coarse than most of the specific SLOSH domains because it covers regions as opposed to small-scale basins that can be affected by landfalling tropical cyclones.
NWS Forecasts
Although extratropical storm surge is not officially forecast, it is mentioned in guidance from the Ocean Prediction Center in the marine weather discussions, and in coastal flood advisories issued by local NWS weather forecast offices.Recent Notable Case
November 9-13, 2009 marked a significant extratropical storm surge event on the US east coast. The extratropical remnants of Hurricane IdaHurricane Ida (2009)
Hurricane Ida was the strongest landfalling tropical cyclone during the 2009 Atlantic hurricane season, crossing the coastline of Nicaragua with winds of 80 mph . The remnants of the storm became a powerful nor'easter that caused widespread damage along coastal areas of the Mid-Atlantic States...
developed into a Nor Easter off the Southeast US coast. During the event, storm force winds from the E were present along the northern periphery of the low pressure center for a number of days, forcing water into locations such as Chesapeake Bay. Water levels rose significantly, and remained as high as 8 feet above normal in numerous locations throughout the Chesapeake for a number of days as water was continually built-up inside the estuary from the onshore winds and freshwater rains flowing into the bay. In many locations, water levels were shy of records by only a tenth of a foot.