Surging Seas and Hybrid Storms

NASA officials nicknamed Hurricane Sandy “Bride of Frankenstorm.” Strange behavior patterns—hitting the northeast as a mix of nor’easter blizzard and hurricane conditions created a powerful hybrid storm that affected many communities. In Maine, we felt the storm’s most severe impacts the night of the full moon on October 29th. Footage of storm surge on the news looked like the forceful wave action in “Thunder Hole” at Acadia National Park. Throughout New England, New York and New Jersey, many people were still without power when the nor’easter hit this week. Hurricane Sandy’s unusual hybrid classification and other factors set a precedent. Coupled with the tides of the full moon, storm surge was more intense, causing more flooding to occur. Are we likely to see and experience powerful hybrid storms like this in the future? What tools are available to predict storm surge?

Forecasters called Hurricane Sandy a “perfect storm.” View photos of the storm as seen from space. Last winter Strange Wetlands reported on the Red Cross/Red Crescent’sinvolvement in the IPCC report on the link between extreme weather disasters and climate change. This week Climate Central’s Surging Seas tool demonstrated how effects of climate change, including sea level rise and storm surge, made Hurricane Sandy worsethan it might have been otherwise.

Federal agencies such as the U.S. Army Corps of Engineers and NASA have been measuring storm surge for many decades, since the 1960s (see above)—long before most people started talking about sea level rise. According to a NASA presentation on An Analysis of Storm Surge Attenuation using USGS, FEMA and NASA data, there is historical data to support the claim that wetlands significantly reduce storm surge. Wetland scientists in the 1960s asserted that 2.7 miles of wetlands reduced storm surge by 1 foot. More recent data from Hurricane Rita was used to assess the storm impacts to wetlands (such as causing wetland loss) as well as wetlands’ role in lessening the effects of storm surge. Therefore wetland losses along the Gulf of Mexico coastline in Louisiana, for instance, and along other areas of coastline on the eastern seaboard, intensified the amount of storm surge during recent hurricanes, such as Hurricane Irene and Sandy. (Fitzpatrick, et. al. 2008) Also see Storm Surge Reduction by Wetlands.

While SLAMM—Sea Level Affecting Marsh Model—may be familiar to you, a tool used in analyzing sea level rise, especially with respect to wetlands, have you heard of SLOSH? Sea, Lake and Overland Surges from Hurricanes, (SLOSH) is a tool used to analyze storm surgeHurricane Sandy’s storm surge was mapped before it made landfall. The SLOSH model was applied to Hurricane Sandy prior to Oct. 29th and it analyzed surges of various levels (2 feet, 3 feet, 4 feet, etc.) At most locations, meteorologists predicted unprecedented levels of surgeusing this tool and other analyses. Tools like SLOSH are only as good as the available data. Future budget cuts threaten data collection tools, such as ocean bouysOther storm surge analysis tools were used to predict Sandy’s surge levels and ultimately, citizens were evacuated in areas where the path of the storm surge was predicted on the maps using those models.

Some useful fact sheets and further reading on the importance of wetlands in preventing storm surge are linked below:

Storm surge & wetlands in Louisiana (NWF fact sheet)
Mitigating Storm Surge with Vegetation & Wetlands (Army Corps of Engineers, 2007)
Analysis of Storm Surge Attenuation & Wetlands (NASA) (2008)
The potential of wetlands in reducing storm surge (Ocean Engineering, 2010)
Hurricane Sandy Geospatial Resources (NOAA Digital Coast, 2012)

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