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Hurricane Role of River Forecast Centers Detailed
By Jessica Harper
NWS Communications Office/Public Affairs Intern
Some of the most violent tropical storms the Southeastern United States has ever experienced challenged NOAA forecasters to keep thousands of square miles of the region up to date on flooding that resulted once the storms roared ashore during the recently concluded 2004 Atlantic Hurricane Season.
Scientists at the NWS Middle Atlantic River Forecast Center (MARFC) in State College, PA, and the Southeast River Forecast Center (SERFC) in Peachtree City, GA, collaborated with the National Centers for Environmental Prediction (NCEP)'s Tropical Prediction Center (TPC), and Hydrometeorological Prediction Center (HPC) and local Weather Forecast Offices (WFOs) during Hurricanes Alex, Charley, Frances, Gaston, Ivan, and Jeanne and Tropical Storms Bonnie, Hermine, and Matthew to track and provide river forecast guidance which helped to reduce damage from excessive flooding.
"This has been an unprecedented tropical storm season," Peter Ahnert, Hydrologist-in-Charge at MARFC, said. "Throughout August and September, the River Forecast Center collaborated extensively with all seven of the Weather Forecast Offices we serve to provide the highly populated Mid-Atlantic region with the best possible river flood forecasts and flash flood warnings for each storm.
"The RFCs made a number of preparations before Hurricanes Charley, Frances, and Ivan struck.
"We begin our work three, four, or even five days in advance," John Feldt, Hydrologist-in-Charge at SERFC, said. "Inland flood impacts over the southeast U.S. include flash and urban flooding, closed basin flooding, dam breaks and mudslides, in addition to main stream river flooding."
The MARFC and SERFC provided flood and high-water forecasts that ultimately benefited industry and utilities, dam operators, and recreation interests to states in the Middle Atlantic and along the Southeastern seaboard.
After Ivan made landfall, heavy rains pounded many areas, including the northern portions of the Susquehanna River Basin, causing the river levels to rise rapidly.
"Public officials in Wilkes-Barre, PA, were seriously considering the evacuation of 100,000 people in and around the city because they feared flood levees protecting the city would be overtopped," Ahnert recounted. "MARFC hydrologists, utilizing recently improved hydrologic models in combination with many years of experience, conveyed confidence to the Binghamton, NY, Weather Forecast Office (WFO) forecasters that the river would crest several feet below the top of the levees. WFO Binghamton immediately relayed the new forecast to the city, which was a major relief to city officials. They also briefed the Department of Homeland Security on the situation. The decision not to evacuate saved the city millions of dollars and spared its citizens unnecessary worry and inconvenience.
"David Nicosia, Warning Coordination Meteorologist (WCM) at WFO Binghamton, attributes the success at Wilkes-Barre to the confidence the RFCs provided NWS meteorologists.
"During the Ivan flood, the support of the RFCs was critical to the success of NWS," Nicosia said. "The RFCs routing technology is paramount to the NWS' victories during hurricane season. The RFCs gave us the confidence to make better projections during briefings."
Employees from the MARFC, SERFC and other river forecast centers contributed to pre-hurricane briefings arranged by the NHC's Hurricane Liaison Team. This team gave a projected overview of how rivers and streams would respond to the storms heavy rains.
Apart from participating in briefings, many RFC forecasters put in extremely long hours before, during, and after each hurricane to provide their region with the best service possible.
"We change our focus before and during a hurricane by extending a workday to 24 hours and adding resources to normal operations," Feldt said. "The SERFC coordinates with a wide variety of partners, providing briefings to the Federal Emergency Management Agency, U.S. Army Corps and Engineers, U.S. Geological Survey, State Divisions of Emergency Management, Water Management Districts, and others."
Although most hurricanes, in recent years, have affected the southeastern states, it is not uncommon for the Middle Atlantic and New England states to experience either the full impact or after-effect of these storms. Over fifty percent of the hurricane deaths and much of the damage is the result of flooding.
"Most people know about the work the NWS does with tornado and hurricane forecasting, but they are unfamiliar with the RFCs' impact on flood and flash flood forecasting," said Gary Carter, Director of Hydrological Development (OHD), NWS Headquarters. "We need to educate the public about how and why the RFCs support and collaborate within the NWS."
Part of this education effort came to fruition in April 2004 when The Weather Channel (TWC) broadcasted the Forecast Earth feature Water's Fury. The 22-minute episode was commissioned by the NWS and produced in collaboration with TWC. It focused on the NWS' role as the Nation's sole provider of hydrologic forecast information and the modernization and enhancement of hydrologic services through the implementation of the Advanced Hydrologic Prediction Service (AHPS). The role of the RFCs in the production of valuable forecast information for river and flash floods and water management was highlighted. "AHPS is incorporating new advanced modeling capabilities and probabilistic forecasting, in addition to improved display and dissemination via web based displays." Ahnert said.
"AHPS implementation continues. AHPS has already resulted in improvements in river forecast accuracy from new and better calibrated models. An example of where we are headed in the near future can be seen in flood inundation mapping systems being tested by SERFC and MARFC," he added. "People will be able to go online, see a detailed map of their town, and see whether or not flood waters will reach their neighborhood.
"As part of the river forecast process, MARFC and SERFC work closely with NCEP's HPC to produce quantitative precipitation forecasts to evaluate when, where and how much rain will fall. Other data needed to produce river forecasts include temperature and evaporation observations and forecasts and observations of tides, reservoir inflow and outflow, and river flow or height. The RFCs receive their observed data from many different sources including the US Geological Survey and the NWS Cooperative Observer program.
The RFCs use these data in the NWS River Forecast System, which takes into account watershed
features such as topography, vegetation, river channel and valley shape, soil properties, and land use in the production of short and extended range stream flow forecasts, and Flash Flood Guidance.
Whether they collaborate with other offices within the NWS and NOAA, or with outside federal, state, and local agencies, the RFCs are constantly partnering with other organizations to secure the well-being of the people they serve.
"The secret to our success is that we are always ready and willing to work with the WFOs," Feldt said. "The WFOs are specialists on a local level. At SERFC, we do our best to assist them by providing a hydrological science perspective and regional picture that are broader in scope."
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