If you were to combine the forces of the Hurricane of 1938, Hurricane Carol (’54), and Hurricane Esther (’61), it would be devastating to Rhode Island.
The combined features of all these storms to create the hypothetical “Hurricane Rhody” might be the worst-case scenario for the state, with strong winds over 70 mph and considerable coastal and inland flooding, according to Isaac Ginis, hurricane expert at the University of Rhode Island Graduate School of Oceanography, during his presentation at a R.I. Shoreline Change Special Area Management Plan (Beach SAMP)stakeholder meeting on July 24.
“Hurricane Rhody” would track similarly to Hurricane Carol, but with forward speed close to that of the Hurricane of 1938 (over 50mph), and then would slow down and make a loop like Hurricane Esther, dumping a significant amount of rain (more than 20 inches). Ginis explained how he used various coastal prediction models to apply such a scenario and assess the potential impact of this kind of storm.
Rhode Island has known its share of hurricanes, with several leaving trails of severe damage. Historically, 56 hurricanes have impacted Rhode Island since 1851, most of which were not significant, but a few were. We know there’s a threat, based on this historical experience. But what about the risks?
“Have we seen the worse-case scenario?” asked Ginis. “If not, what does that look like? And how will climate change impact hurricanes?”
We’re in the midst of hurricane season, which starts in June and ends in November and have, thus far, dodged any real impacts other than a rainy holiday from the only storm that came our way. Hurricane Arthur had weakened after making landfall in the Outer Banks earlier in the season, and headed further offshore by the time it came to Rhode Island. However, there are still several months left in the hurricane season.
What we may find in the future, according to Ginis, is either the same number of storms or fewer in a season, but with greater intensity.
“We’ll see more Category 4 and 5 storms,” he said. This is largely attributed to the impacts of climate change, as warmer water fuels these types of storms. “Hurricanes draw energy from the ocean, from evaporation,” said Ginis, explaining that as the climate gets warmer it will feed more energy into these storms. “Hurricanes love warm water. The higher the temperature, the higher the potential for hurricanes to gain energy.”
Although hurricanes may increase in intensity,the impact in Rhode Island is still largely unknown as a storm’s structure – wind range and rainfall pattern, and overall strength – is dependent on landfall, path, and speed.
“Hurricanes that approach Rhode Island and New England, in general, often change structure,” said Ginis, explaining that friction at a particular location, or the texture of the landscape, affects wind and rain patterns, and range. [divider style=”solid” color=”#eeeeee” width=”1px”]
WATCH THE WEBCAST [divider style=”solid” color=”#eeeeee” width=”1px”] Every hurricane has a different “footprint” based on where they land, which is why hurricanes are felt differently here than those in southern states like Florida. For Rhode Island, hurricanes hit colder water that can slow and weaken the storm, but those that make landfall to the west generally produce the strongest winds.
“Typically, hurricanes build in the warm tropics coming up north along the Gulf Stream,” said Ginis. “They typically make a sharp turn east just after Hatteras, hitting colder water and fading out. This is one of the reasons why New England isn’t hit as hard as southern states.” This “footprint”, however, says Ginis, isn’t accounted for in the NOAA SLOSH (sea, lake and overland surges from hurricanes) models, developed in the 1960s and currently used to predict hurricanes, which assumes all hurricanes are symmetrical with very limited wind change.
“The SLOSH model doesn’t account for the change in wind structure,” said Ginis, emphasizing how landfall location dictates wind patterns. “We don’t have the right modeling tools to fully understand the risks.”
Most people who die in storms drown. – Isaac Ginis
Different geographies – homes, forests, fields, rivers, etc. – have different surface characteristics that dramatically affect the winds near the ground, and are responsible for most of the local wind variability. It’s this variability that Ginis says is lacking from the current models.
While the public is generally more aware of wind damage from hurricanes, they aren’t as up to speed on the impacts of flooding and storm surge, said Joe Warner, Building/Zoning Official and Floodplain Manager for the Town of Charlestown at the Beach SAMP meeting. Ginis attributes this lack of awareness to reports that mainly refer to wind speeds.
“Forecasters hate this scale,” said Ginis in reference to how hurricanes are graded based on wind speeds. “It doesn’t represent the full threat. Most people who die in storms drown.”
The National Hurricane Center is beginning to produce flood maps, according to Ginis, that show real time predictions every six hours of water elevation, so people have a better sense of what flooding scenario to expect.
Although this is a step forward, Ginis stressed better wind, coastal and inland flood modeling tools are needed to analyze the risks to better prepare for, and mitigate, hurricane hazards in Rhode Island.
Ginis’ research incorporates a multi-model approach to assess climate change factors, such as sea level rise, and atmospheric and oceanic conditions.
“If you are just looking at only one model you’re prone to make several significant errors in your assessments,” he said.
This research will contribute to improve NOAA’s overall hurricane tracking, forecasting, and understanding of potential impacts, and will be incorporated into the state’s Beach SAMP project to improve hurricane risk analysis in Rhode Island.
[info]For more information about future stakeholder meetings please visit Beach Special Area Management Plan [/info]