![\"Main](\"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/wp-content\/uploads\/sites\/13\/2014\/04\/Creswell11.jpg\")
“The severity of the storm was the impetus to do this,” says Brian Cullen, senior forecaster. Furthermore, colleagues from other offices were willing to help. “It was a real team effort,” he adds.<\/p>\n\n\n\n
The teams sought high-water marks and debris lines. High-water marks show the height of the floodwaters at a particular location. Debris lines \u2014 piles of pine needles, leaves and other materials from the river bank \u2014 show how far from the shore or bank the water went and allow surveyors to calculate how high the water rose from its normal level.<\/p>\n\n\n\n
Finding high-water marks required some detective work, recalls Nick Petro, Raleigh’s warning coordination meteorologist. Waves and receding floodwaters removed the marks from some buildings. And even though the team started their surveys as soon as possible, residents had cleaned off some markings by the time they arrived.<\/p>\n\n\n\n
Petro and Mike Moneypenny, also from the NWS in Raleigh, joined Cullen in his survey along the southern shore of the Albemarle Sound and northern Outer Banks. The three men reported one common theme: Many residents had not seen floodwater that high before. In spite of the weather forecasts predicting heavy flooding, the magnitude of the flooding had caught many by surprise.<\/p>\n\n\n\n
By the time it hit North Carolina, Irene was a Category 1 hurricane. “That’s not particularly rare,” Cullen says of Irene’s strength. “But from a water perspective, it was unusual.”<\/p>\n\n\n\n
Based on a flooding anecdote, Petro estimates that some areas near Columbia experienced a 1.5 hour surge: 45 minutes in and 45 minutes out. “The water came in very quickly,” he notes. “Do not underestimate how significant surge can be coming from the sounds.”<\/p>\n\n\n\n
EXPERIMENTAL SYSTEM TESTED<\/h2>\n\n\n\n
Forecasters sift through information from storm models when building their prediction for a storm. These models anticipate how certain conditions \u2014 such as storm direction, rainfall and storm surge \u2014 could develop or change. Occasionally, forecasters use data from experimental systems. One such model is the Coastal and Inland Flooding Observation and Warning project, also known as CI-FLOW. This project is led by NOAA’s National Severe Storms Laboratory in Norman, Okla.<\/p>\n\n\n\n
CI-FLOW was born out of a need that became apparent after Hurricanes Dennis and Floyd devastated North Carolina. These hurricanes surprised everyone with the destruction caused by storm surge and heavy rain, rather than wind.<\/p>\n\n\n\n
“It was quite obvious that better water-level predictions were needed to prevent the loss of life and property,” says Jack Thigpen, North Carolina Sea Grant extension director.<\/p>\n\n\n\n
The National Sea Grant Office, NOAA, NSSL and several state Sea Grant programs \u2014 including North Carolina Sea Grant \u2014 began a collaboration with university researchers to model the water-related effects of a coastal storm. This led to CI-FLOW.<\/p>\n\n\n\n
This system predicts total water levels in the Tar-Pamlico and Neuse river basins, where Dennis and Floyd wreaked the most havoc. CI-FLOW takes into account the combined influence of rainfall, river flows, surge, and ocean waves and tides. It is tested when coastal storms approach and its data are available, through a password-protected site, to select people, including NWS staff in North Carolina.<\/p>\n\n\n\n As an experimental system, CI-FLOW depends on good post-storm data to verify its results and determine what changes to its models are still needed. Its predictions before and during the storm should accurately reflect actual conditions, which is where Rogers and the NWS staff come in. The information they collect could be used to build the post-Irene picture and verify the accuracy of CI-FLOW \u2014 and other models \u2014 for that event.<\/p>\n\n\n\n Prior to Irene, CI-FLOW was used in real time during Earl and Nicole. Before that, it had used archived data.<\/p>\n\n\n\n “Hurricane Irene provided a unique opportunity for the CI-FLOW researchers to demonstrate the capability to routinely predict total water level and inundation in real time,” says Kodi Monroe, who heads the CIFLOW project. She is a Sea Grant-funded researcher at NSSL.<\/p>\n\n\n\n “CI-FLOW is experimental,” Cullen emphasizes. However, during Irene, he noted that some of CI-FLOW’s preliminary information was similar to that from other surge models. He was able to use data from this test system \u2014 combined with that from other established models \u2014 to develop his surge range prediction for the emergency manager at the U.S. Marine Corps base in Cherry Point.<\/p>\n\n\n\n Cullen points out that CI-FLOW worked in this case because he was providing specific information from the Neuse River, one of CI-FLOW’s focus areas. “CI-FLOW has led to more confidence in our storm-surge forecast in the Neuse,” he says.<\/p>\n\n\n\n Moneypenny, a hydrologist, points out one useful outcome of Irene’s flooding: “To end a drought, you need a flood.”<\/p>\n\n\n\n Irene brought heavy rain east of the I-95 corridor. The rain replenished the shallow wells and aquifers in the coastal region. “They couldn’t have gotten it in a better place,” he adds.<\/p>\n\n\n\n By the time the hurricane passed, the severe or extreme drought in the eastern third of the state was gone. A week later, Tropical Storm Lee passed over the state.<\/p>\n\n\n\n “Irene took care of the coast,” Petro says. “Lee took care of the western counties.”<\/p>\n\n\n\n However, the entire state didn’t get an equal share of rain. Rainfall totals went from more than 10 inches to less than an inch within a narrow zone. Even after rain from Irene and Lee, central North Carolina, including the Triangle, remained abnormally dry or in moderate drought in late September. “The piedmont was short-changed,” Moneypenny says.<\/p>\n\n\n\n Irene arrived too late to help farmers in the state. By late August, many crops, including corn, had been declared a loss and plowed under. Replacement crops also were stressed because of the continued lack of water. Flooding from Irene compounded the problem.<\/p>\n\n\n\n “Crops were rotting in the field with their roots submerged,” he adds. Any hopes farmers had of getting a late crop were likely drowned by Irene’s floods.<\/p>\n\n\n\n Many lives and livelihoods, and much property were affected by the flooding that Irene brought to the coastal and estuarine areas. Infrastructure changes along the waterfront and near-water areas, locations that have seen a lot of construction, also magnified the impact of the storm. “We will continue to see more impacts as long as people continue to build,” Cullen says.<\/p>\n\n\n\n “It’s fascinating, as an observer of the weather,” Petro says of hurricanes and the destruction they bring. But his work allows him to give people advance notice of weather dangers.<\/p>\n\n\n\n “My goal is to save lives and property,” he concludes.<\/p>\n\n\n\n For more information, visit the USGS Irene site (water.usgs.gov\/osw\/floods\/2011_HIrene\/), National Weather Service (www.nws.noaa. gov) or CI-FLOW (www.nssl.noaa.gov\/ciflow\/). To see the state’s latest crop report, go to: www.ncagr.gov.<\/p>\n\n\n\n This article was published in the Holiday 2011<\/a> issue of Coastwatch.<\/em><\/p>\n\n\n\n![\"Irene](\"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/wp-content\/uploads\/sites\/13\/2014\/04\/Columbia_SouthShoreAlbemarle.jpg\")
TWO SIDES TO A COIN<\/h2>\n\n\n\n