Sea monsters

Coastal storms research helps Maine anticipate and prepare for extreme weather
Surf crashes along the shoreline in Camp Ellis, Maine. Winter coastal storms and other strong weather events that occur year-round in Maine are increasing in frequency and intensity. Photo by Jill Brady/Portland Press Herald/Getty Images

Sea monsters

Coastal storms research helps Maine anticipate and prepare for extreme weather

On Jan. 4, 2018, a powerful storm pummeled Maine, bringing blizzard conditions and strong winds out of the Northeast. On the coast, the peak of the storm arrived at the same time as the highest tide of the year due to the position of the Earth and moon.

Waves surged over breakwaters and seawalls and into coastal towns, carrying seaweed and blocks of ice into yards and closing roadways. The path of damage followed Route 1 from York and Scarborough to Lincolnville and Lubec, where currents dislodged the historic McCurdy’s Smokehouse brining shed and sent it floating toward Canada.

Seawater submerged landmarks — Chebeague Island pier, Boothbay Harbor footbridge, Rockland Breakwater and Deer Isle causeway.

Downtown waterfronts of Portland, Kennebunkport, Damariscotta and Belfast were inundated.

The winds caused a storm surge over 2 feet, pushing the storm tide to 13.8 feet at the Portland tide gauge, the third-highest water level on record and the worst tidal flooding since the Blizzard of 1978. The tide remained above flood stage for nearly three hours, causing millions of dollars in damage statewide.

“This storm produced the highest water levels along the coast in decades,” says John Cannon, a meteorologist with the National Weather Service (NWS) in Gray.

It was one in a series of major nor’easters in Maine in recent years.

These winter coastal storms, also known as “extratropical cyclones,” move up the Eastern Seaboard and then, after crossing Long Island, Cape Cod and the shallow banks of the Gulf of Maine, track east toward Nova Scotia as winds spiral back from the Northeast. Strong storms also occur occasionally at other times of the year: hurricanes in summer and hybrid storms in late fall, such as Superstorm Sandy and the Perfect Storm of 1991, when the water is warm enough to support a hurricane, but the jet stream has moved to its winter position that generates winds out of the Northeast.

For most of Maine, the greatest damage comes when storms move slowly, and thus have time to generate large, battering waves. Especially when a storm coincides with a high astronomical tide, according to Cannon, who, since 2012, has worked with University of Maine researchers to improve storm models and forecasts.

Wave data for the models come from a network of buoys in the Gulf of Maine, part of the Northeastern Regional Association of Coastal Ocean Observing Systems. The buoys are maintained by Neal Pettigrew, professor in the UMaine School of Marine Sciences.

“Wave information is essential for characterizing storms, probably more so than actual wind direction or barometric pressure,” Cannon says. “The buoy network shows differences in open ocean waves along the coast that are a result of storm tracks. Storm tracks are part of our forecast, designed to give enough lead time to warn coastal communities.”

While the January storm did not inflict a lot of wave damage, it did illustrate more areas that are — and will continue to be — vulnerable to flooding.

As the “saltiest guy” in the NWS office, Cannon looks at storms from a coastal perspective. Waves are his passion. His forecasts focus on the narrow zone where ocean meets land and where storm winds pile up water, forcing it farther inland — a phenomenon known as storm surge. Strong winds can whip up waves on top of the surge, making it that much worse.

“Observations over the past couple decades show an overall increase in intense rain and snowstorms.” Sean Birkel

Forecast models used by the National Weather Service today are nimble, able to reveal and predict conditions within the short time window required in the fast-paced world of changing weather. In the case of the Jan. 4 storm, computer models sent conflicting signals, showing a likelihood for “moderate” flooding well in advance of the storm, but underestimating the magnitude of the event.

“The storm tide built up faster than predicted despite a northerly wind direction, which normally is less problematic as the winds were not onshore in this case. Meteorologists plan on studying this event to determine why it was so significant,” says Cannon.

“Every storm provides new information about the coastal processes involving the wind, wave and storm surge relationships along Maine’s unique and complex shoreline.”

In 2014, with funding from Maine Sea Grant, Cannon began collaborating with university researchers who have access to powerful computer models and the latest ocean data.

“It is a really big project, because we are including flooding and erosion, landscape features and future projections,” says Dongmei Xie, who conducted the Ph.D. research under Jean MacRae, associate professor of civil and environmental engineering, and former UMaine researcher Qingping Zou.

In the project’s first phase, Xie combined existing open-source models of waves, tides, surge and ocean circulation, and zoomed in on the Saco Bay region, which is the largest stretch of beach in Maine and has perennial issues with flooding and erosion.

Then, she added high-resolution, large-scale maps of the ocean floor (bathymetry) and coastal zone, both of which influence the force and direction of waves and currents. The bathymetry allows for modeling water depth in addition to the lateral extent of flooding — not just how far inland, but how deep flooding will be. The dynamic model calculates the path of water through the bay, around islands and over land.

With more accurate representations of the coastline, Xie validated the newly adjusted model using data from the April 2007 nor’easter known as the Patriots Day Storm. That storm generated big waves that were recorded by wave buoys and a surge recorded by tide gauges. The slower a system moves, the more time there is for damaging waves to develop. As winds increase, wave energy increases dramatically.

The Patriots Day Storm lasted through multiple high tides. A surge of nearly 3 feet flooded Saco Bay, inundating not only flood-prone areas like Camp Ellis and Scarborough River, but also Goosefare Brook and most of the Ocean Park neighborhood.

The “clouds-to-coast” approach, which integrates multiple models of weather, tides, currents, wave movement and land interaction processes specific to local areas, makes Xie’s work unique from existing models that take more of a “bathtub” approach and predict flooding over land as static, or of equal height across different areas.

After testing the models, Xie and her colleagues asked themselves what information they could provide to local communities, such as the effect of storm surge where it intersects and overtops coastal infrastructure like seawalls.

“We can actually predict how areas will flood, and how to apply the information to other areas, such as rebuilding seawalls or making dunes taller for coastal adaptation and flood mitigation,” she says.

Xie also has generated maps predicting flooding with different sea level rise scenarios.

In the past century, sea level along the Maine coast has risen approximately 2 millimeters per year — about 7.5 inches per century — similar to global ocean trends, according to the Maine Geological Survey.

However, over the last 20 years, global sea level rise rates have almost doubled.

“I am concerned with the recent strength of storms that have approached hurricane strength. We may be looking ahead to a time when ‘wintercanes’ are more problematic than the dreaded nor’easter.” Stephen Dickson

Data from the Portland tide gauge also have shown an increased rate — about 3 millimeters per year. Some of the highest annual mean sea levels ever recorded in Portland have occurred since 2009.

Coastal erosion is another concern. To address this, Xie added data on sea floor sediment, which is picked up by storm waves and moved by currents.

“We want to see where the most erosion happens, and make corrections based on actual data on sand grain size,” she says.

With millions of data points, Xie’s model is slow, taking hours to run its computations. But since the results successfully mirrored what happened during past storms, they know the programs can be used to improve short-term forecasts.

“Our next step is to work with the National Weather Service to make the model usable, improving the computational efficiency so that it can run automatically and produce real-time forecasts,” says Xie.

Cannon is responsible for how the information ultimately will be applied. For example, forecasts provided to towns could help them prepare for a storm, and emergency managers could activate Citizen Emergency Response Teams to assist the public.

The Northeast Regional Ocean Council has cited a need to enhance ocean observing systems to support storm surge and flood forecasting and response.

To address this need, Cannon works with another team of UMaine researchers, including Damian Brady, Huijie Xue and graduate student Stephen Moore, to look at present and future storm patterns and storm surge in Saco and Casco bays.

In their work, funded by the National Science Foundation (NSF), they also use computer models of historic storms, such as the Blizzard of ’78 and Patriots Day Storm, to study the individual components that lead to storm tides.

Moore looks at salinity, atmospheric pressure and other elements to better understand their contribution to storm tides and the resulting coastal inundation. Their models have been successful in simulating storms of record, and they are creating inundation risk maps under varying sea level rise scenarios for two major storm events.

Eventually, the UMaine research will help towns plan for future flooding and erosion. Meanwhile, for real-time data on storm impacts, Cannon has turned to citizen volunteers with the Southern Maine Volunteer Beach Profile Monitoring Program who provide measurements of beach erosion before and after storms.

Storm surge is acute, visible and dramatic — a sudden realization of global climate change that most of the time seems subtle and slow.

Both the effects of climate change on the coast and people’s engagement with climate change are part of the NSF-funded Sensing Storm Surge Project.

Project leaders are Kimberly Huguenard and undergraduate student Kyah Lucky in the Department of Civil and Environmental Engineering, and Laura Rickard and graduate students Abby Roche and Kevin Duffy in the Department of Communication and Journalism.

Huguenard, whose specialty is coastal engineering and water resources, wanted to look at storm surge in systems with different physical characteristics.

Rickard is interested in the human dimension. How can we improve the warnings associated with wind, waves and flooding so that people respond?
The team recruited 20 citizen scientists to monitor water levels using computerized instruments deployed in three locations: Bass Harbor bay and marsh on Mount Desert Island; the small, uniquely shaped Bagaduce estuary; and Penobscot Bay, where a large, funnel-shaped estuary amplifies storm surge.

Beach erosion on the coast of Maine

A March storm with powerful waves washed out parts of Surf Street in Saco, damaging dune grass that helps protect the beach from erosion. The Saco Bay region, the site of the largest stretch of beach in Maine with perennial issues of flooding and erosion, has been the focus of UMaine modeling research to predict how areas will flood. Photo by Gregory Rec/Portland Press Herald/Getty Images

Volunteers collect data once a month and upload their information with narrative and photos to the project website.

Students Lucky and Roche pounded the pavement to recruit volunteers. They had the most success on Mount Desert Island, where they found year-round residents with access to the water and an interest in the project. Rickard’s research tracks volunteer activity, and how they think and feel about the data they are collecting.

“There’s not a lot of information on reliability of data collected by volunteers or comparisons of different training methods for citizen scientists,” says Rickard. “We also want to know what makes people engage in climate change issues.”

Storm damage is happening against a backdrop of rising sea levels, the result of ocean warming, expanding water and melting glaciers forcing the sea higher against the East Coast.

According to the 2015 “Maine’s Climate Future” report, the frequency of intense precipitation events, with more than 2 inches of rainfall in a 24-hour period, has increased across the state.

The Jan. 4 storm’s “bomb” in falling pressure generated winds, although the waves didn’t get a chance to develop prior to high tide, so the erosion aspect was not as critical as it could have been, according to Cannon.

“I am concerned with the recent strength of storms that have approached hurricane strength. We may be looking ahead to a time when ‘wintercanes’ are more problematic than the dreaded nor’easter,” says Stephen Dickson of the Maine Geological Survey.

Dickson also worries about shifts in the larger, global climate system that drives our seasonal weather. His Ph.D. work at UMaine suggested that beaches, dunes and other natural coastal barriers may owe their existence to upwelling currents forced by the prevailing westerly winds of the jet stream. Storm tracks affect wind direction, and winds drive currents that can deposit sand on beaches, or wash it away.

“If the jet stream changes significantly as it does in El Niño winters or in polar vortex wobbles, westerlies of the past that built Maine’s beaches may not be as prevalent to restore beaches after future storm erosion,” he says.

Understanding current and future storm tracks and beach responses will be critical to predict if the balance will “make or break” Maine beaches.

Sean Birkel, Maine state climatologist and research assistant professor in the UMaine Climate Change Institute, and Ph.D. student Julia Simonson are working on ways to incorporate storm damage predictions into weather forecast models. They are using 2013 ice storm information and an analysis of how severity of coastal storms is likely to change.

“Observations over the past couple decades show an overall increase in intense rain and snowstorms,” Birkel says. “The intensification has been tied to changes in air circulation across the Northern Hemisphere stemming from warming oceans and steep decline of Arctic sea ice.

“The tendency toward more extreme storm events is likely a new normal,” says Birkel.

To Cannon, research universities like UMaine have the hardware, technology and time to study storms such as the Jan. 4 blizzard with fine detail. NWS has the capability to locally run and distribute computer models, analyze output and create a forecast in a short temporal schedule.

“These two approaches and methodologies complement each other,” Cannon says. “Other storms more intense than the Jan. 4 blizzard will come. It’s all just a matter of time — and we need to prepare accordingly.”

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