The large and slow-moving storm Isaac is likely to bring long periods of wind and rain resulting in downed trees, flooding and power outages in the Baton Rouge area, according to weather forecasters, city-parish officials and utility company representatives.
Monday forecasts for Tropical Storm Isaac indicate that sustained winds of 20 miles per hour could be felt in Baton Rouge for 83 hours. In comparison, Hurricane Gustav in 2008, which caused widespread damage in the region, had sustained winds of at least 20 miles per hour lasting for 15 hours.
“I’ve never seen winds persist for that long,” Barry Keim, state climatologist, said of the forecast.
Forecasts from the National Weather Service show that sustained winds from Isaac of 40 miles per hour could last 22 hours, from 6 a.m. Wednesday to 4 a.m. Thursday, and wind speeds of 50 miles per hour are forecast to run from 7 a.m. Wednesday to 5 p.m. Wednesday.
“That’s going to be quite a run,” Keim said.
In addition, the forecast calls for peak gusts of 91 miles per hour at the height of the storm in Baton Rouge.
“Winds of that magnitude are on par with what we had with Gustav,” Keim said.
Keim cautioned that the forecasts are meant as guides for what generally could happen, but there is always uncertainty.
Although the storm is forecast to make landfall Tuesday evening around 7 p.m. as a hurricane in the Barataria Bay area of Louisiana’s coast, its effects will be felt long before then, Keim said. The wind in Baton Rouge will start picking up Tuesday morning and by the afternoon the forecast calls for sustained winds of about 35 mph, with gusts up to 48 miles per hour.
Wind speeds will take a jump around 7 a.m. Wednesday and are expected reach 74 mph sustained with gusts of up to 91 mph by noon Wednesday, according to forecasts from the National Weather Service.
The longer the wind blows, the greater the chance that trees will come down, said Sheila Pounders, regional customer service manager for Entergy Gulf States Louisiana. When trees come down, they also can take power lines with them.
“Customers need to be prepared now for outages,” she said. “The longer it (the wind) stays, the more damage it does.”
Rainfall is another concern with the storm, with estimates ranging from four to 20 inches over a five-day period. Although forecasts Monday called for the heaviest rain to be over Slidell and southwest Mississippi, Keim said a shift in the storm’s path will change where rain will fall the most heavily.
As a general rule, rain and wind is higher on the right side of a storm, although there have been exceptions, he said.
Bob Hearn, environmental engineer with the city-parish Department of Public Works, said Hurricane Gustav created 2.2 million cubic yards of woody waste that needed to be disposed of, much more than the half-million cubic yards from Hurricane Katrina a few years earlier.
“That was the worst we ever had,” Hearn said, referring to Gustav.
Although a lot of trees came down during Hurricane Gustav, Hearn said, Baton Rouge is an area that just has a lot of trees so it’s hard to say if the weaker trees were taken out by that earlier hurricane. Water oaks are a problem tree in the area because they don’t have a very good or deep root structure, making them vulnerable to wind.
Hearn said city-parish staff has been meeting with the contractor hired to deal with debris removal in preparation for the storm. He said the city-parish is as prepared as it can be to deal with the aftermath of Isaac, but there is no way to accurately forecast the damage it may bring.
“We just have to let nature take its course and then deal with nature,” Hearn said. “We’re just waiting to see what happens.”