Cooler and drier winter expected
Despite the forecast for a robust Atlantic hurricane season the eastern United States escaped 2013 unscathed.
Initial forecasts from the National Hurricane Center in May called for 13-19 named storms, an above-average number that was barely reached when tropical storm Melissa sputtered out in the middle of the Atlantic as the 13th named storm in November.
Mike Caropolo, meteorologist in charge at the National Weather Service’s Wilmington office, said the slower than forecasted hurricane season was the result of dry upper-level air throughout the tropical Atlantic Ocean. The two main contributors to these dry conditions were above average levels of Saharan dust off Africa and continuing drought conditions in Brazil.
“The drought and the dust coming off Africa just gets into the upper levels of the atmosphere so when you have a storm trying to develop it doesn’t have the moist atmosphere to feed off and get the energy it needs,” Caropolo said.
The original forecast for an active hurricane season was based on recent history and global atmospheric conditions, Caropolo said.
“We have been in a period of very active tropical activity and we were looking at neutral to La Niña atmospheric conditions over the Pacific, which in itself leads to less wind shear over the tropical Atlantic,” he said. “Plus in the beginning of the year you had the sea surface temperatures above normal … so all those factors were contributing to the outlook of an above normal season.”
Wrightsville Beach Fire Chief Frank Smith said he is always grateful for a quiet season but warned residents not to become slack in their hurricane preparations.
“We are of course very happy it was a quiet, uneventful season,” Smith said. “While that is certainly a good thing for the present time, I think it builds a good deal of complacency where people might not take the threat of a storm as serious as they should.”
One factor that could have lead to increased storm surge impacts this season is Wrightsville’s depleted beach strand with the scheduled four-year renourishment project coming in the spring of 2014. While Smith said the difference the depleted sand levels would have made is impossible to quantify, a healthy, renourished beach strand and dune structure is the best line of defense against storm surge, he said.
In the offseason Smith encouraged Wrightsville Beach’s homeowners to review their hurricane preparedness plans and address any changes that may have occurred to their properties.
“The first step to developing a good personal hurricane response plan is to identify your risks and exposures,” he said. “You could have elderly family members that have special needs or young children or pets or a boat — all those things are things to consider now so you can determine what actions you need to take if you are threatened by a storm.”
Caropolo said the National Hurricane Center’s 2014 hurricane forecast should be announced near the end of May.
In the meantime the NWS is busy forecasting winter storms like Boreas, which passed over the eastern seaboard around Thanksgiving. Long range forecasting for these winter storms is less accurate than that of hurricanes, but Caropolo said the Jetstream’s pattern allows for a shorter forecast.
“The atmospheric oscillations are only good for forecasting out a couple weeks and could flip very easily,” he said. “Right now it is showing a very high amplitude jet stream across the globe, which means that there are a lot of waves in it … so you do get a lot of cold air coming down from the Arctic like we have been experiencing over the past couple weeks.”
Looking to the remainder of winter Caropolo said it would appear the atmospheric conditions are trending toward a cooler season.
“We are in a neutral pattern going toward a slightly El Niño pattern, which would be a little cooler and drier,” he said. “But there will be oscillations in the jet stream so we might have prolonged periods of cold and prolonged periods of temperatures above normal. It is a very humbling science here when you are trying to predict something in the future because there is just too much noise in the atmosphere.”