The Virginia Institute of Marine Science is launching a new online tool that allows locals to gauge the magnitude of coastal flooding and how it might affect where they live.
VIMS’ Tidewatch forecast system comes just in time for the height of Atlantic hurricane season, which typically peaks on Sept. 10. The Historic Triangle has had its share of flooding in the past two years, with Hurricane Irene last year and a nor’easter in November 2009.
Emeritus professor John Boon, lead developer of Tidewatch, said the forecasts will provide citizens timely guidance on what the time and height of the next three high waters are expected to be. “They can use that information to prepare for coastal flooding, whether that involves gathering sand bags, moving possessions to higher ground, adjusting mooring lines for their boat, or choosing an evacuation route,” Boon said in a VIMS press release.
Boon will formally introduce the forecast system during VIMS’ After Hours Lecture at 7 p.m. Thursday in Watermen’s Hall on the VIMS campus in Gloucester Point. Click here to register for the lecture.
The Tidewatch system generates 36-hour public forecasts for nine water-level stations within the Chesapeake Bay, along with a single station on the Eastern Shore. The forecasts, updated every half hour, were previously only available on an experimental basis. The VIMS faculty decided to make the forecasts available to the public after testing increased their confidence in the forecasts’ accuracy. They tested the system with selected waterfront property owners, Virginia Sea Grant, the National Weather Service and emergency managers.
Their testing included performance checks in real-time during Hurricane Irene, tropical storm Ernesto and the November nor’easter, along with “hindcasts” made by feeding data from the year of Hurricane Isabel into the prediction model. The average expected error is now about 3.5 inches at 36 hours forward in time, and about 2.5 inches at 12 hours.
The Tidewatch forecasts were developed in partnership with the National Weather Service researchers at the National Oceanic and Atmospheric Association’s Silver Spring, Md. and Wakefield locations. The Tidewatch forecasts use NOAA’s instrument for forecasting Sea, Lake and Overland Surges from Hurricanes (SLOSH), the predicted astronomical tide and a unique 30-day running average of observed water level.
Tidewatch compares extreme levels of water to the highest astronomical tide, or HAT. Boon said this best indicates how storm tides can affect coastal residents because it gives them a natural benchmark. Points above the HAT appear dry most of the time, he said, but if a Tidewatch forecast predicts water levels will exceed the HAT, coastal residents will know whether a storm will likely affect their property.
