Amid the most active hurricane season in more than a decade, the U.S. Army Corps of Engineers is developing a plan to help Maryland officials better know where and when to order evacuations ahead of tropical cyclones.
Officials have mapped the potential storm surge for cyclones as strong as Category 4 — they don’t believe it’s possible for a Category 5 storm to hit Maryland — and will work with local officials to map out evacuation zones. Then officials will analyze transportation systems to determine how long it would take for residents to clear out.
The evaluation is a regular exercise, but this time is factoring data from recent events — including devastation wrought by Hurricane Sandy in Crisfield, by Hurricane Harvey in Houston, by Hurricane Irma across the Caribbean and Florida, and now by Hurricane Maria in Puerto Rico.
The new plan will take into account lessons learned from those storms, and is using better technology to better predict where coastal inundation could put lives at risk.
Carla Quinn manages the National Hurricane Program for the Army Corps. She said the plan, expected to be finished in time for the 2019 hurricane season, should help emergency managers balance the impulse to delay decisions until storm track and intensity forecasts become clear with the priority of keeping people safe.
“Emergency managers would naturally want to wait to get the best information,” said Quinn, who is based in Baltimore. “But if they don’t know it’s going to take sometimes two days to get people evacuated, they don’t know when the point they have to make that decision is.”
Army Corps officials said the plan will replace similar documents prepared for the Eastern Shore in 2009 and counties along the western shore of the Chesapeake Bay in 2010. Such planning is required periodically along the Gulf of Mexico and Atlantic coasts under the National Hurricane Program, a partnership of the Army Corps, the Federal Emergency Management Agency and the National Oceanic and Atmospheric Administration.
The plan is to incorporate new modeling developed after Sandy caused devastating flooding from Crisfield on Maryland’s Eastern Shore to New York City in 2012.
Before that storm, the hurricane center did not expect the large areas of tropical-force winds and the slow movement that meteorologists saw in Sandy.
The plan is focused on storm surge — the often violent coastal flooding that tropical-force winds push onto shore. In a hurricane, meteorologists say, surge is the greatest threat to life.
The plan’s maps suggest higher storm surge risks in some areas, but lower risks in others, said Debbie Hardick, environmental protection specialist for the Army Corps’ Baltimore district. Army Corps officials declined to share their maps with The Baltimore Sun, but new NOAA maps show a Category 1 hurricane is capable of bringing up to 6 feet of storm surge across much of Dorchester and Somerset counties and around Middle River and White Marsh in Baltimore County. A Category 4 storm could bring surges of water more than 9 feet high across those areas, over Ocean City and along the Sinepuxent and Assawoman bays in Worcester County, the maps show.
In Baltimore, the highest storm surge risks appear around the Inner Harbor, Fells Point and the Fairfield industrial area.
Quinn said the Army Corps’ process prepares for “a reasonable worst-case scenario.” That means trusting science that says a Category 5 storm could not likely ever impact Maryland — ocean and bay temperatures don’t get warm enough to support such an intense storm — but also research and recent history that suggest weather could be more extreme in the future.
“We try to use past experience and look at trends, and use the best science to be able to balance all of the risk factors,” she said.
Maryland Emergency Management Agency spokesman Chas Eby said the current plan was used to evacuate Ocean City, including the large population of international students who work in the beach resort, ahead of Hurricane Irene in 2011.
Eby said officials are looking forward to receiving the updated plan to guide the scope and timing of evacuations.
Hurricane Irma illustrated that evacuating populated coastal areas has become more challenging. Thousands of Floridians spent hours on jammed northbound highways last month in the days ahead of the storm’s landfall. Many fled the Atlantic coast to stay with friends and family on the Gulf Coast, thinking it would take them out of harm’s way, only to find the storm’s unpredictable track had spared their homes but followed them west.
Thomas Laczo is a coastal engineer for the Army Corps in Baltimore. With each update to evacuation plans, he said, it’s important to assess risks using new surveying technology and considering changes in demographics, transportation systems and development.
“Populations are growing, infrastructure is changing,” he said. “It takes a longer time for the population in a certain area to go from Point A to Point B.”
Meanwhile, emergency managers have been working independently of the Army Corps to improve hurricane preparation.
Baltimore County public safety spokeswoman Elise Armacost said officials have been working across the region on updated evacuation planning through a grant from the U.S. Department of Homeland Security.
MEMA recently revised its methods for coordinating state agencies to support county governments. It applied lessons from extreme weather events such as the deadly Ellicott City flood in July 2016 and the record-setting snowstorm of January 2016.
Eby said that work, and the Army Corps plan, are part of efforts to make emergency planning easily adjustable based on the severity of weather events. That way, he said, if the impact is worse than expected, officials can react more quickly.