Potential tropical storm tracks east hours before Louisiana landfall; here’s what to expect – NOLA.com

It seems like southeast Louisiana won’t get as significant a soaking as earlier feared from the slow-forming tropical weather system that the National Hurricane Center avoided naming Tropical Storm Claudette.

Meteorologists with the Slidell office of the National Weather Service said Friday evening that only another 2 to 3 inches of rain would fall between Interstate 55 and the Pearl River Basin through Saturday. Four to 8 additional inches of rain was possible over coastal Mississippi. 

Winds were still expected to gust almost up to tropical storm force, 39 mph, especially south of Interstate 10,  as the storm labeled Potential Tropical Cyclone Three moved inland south of Houma. 

Forecasters said the bulk of the rain was expected to end over southeast Louisiana by midnight as dry air slid into a growing slot on the back side of the low pressure system. 

Sustained winds of 46 mph were reported by at least one oil platform just south of Grand Isle, and Plaquemines Parish officials reported gusts of more than 40 mph at several locations and more than 2 inches of rain at Pointè a la Hache.

At 7 p.m., the disturbance was 100 miles south of Morgan City, with maximum sustained winds of 45 mph, though still not declared a tropical storm. It was headed north at 16 mph.

Forecasters did not expect the storm to strengthen significantly before landfall, because of its broad, asymmetrical structure and because upper-level winds were expected to shear its cloud tops during the short period remaining before landfall, senior hurricane specialist John Cangialosi said. 

“Although the disturbance has wind speeds of tropical storm intensity, it has not been named a tropical storm yet since its center is ill defined and broad, as evident in the Air Force Hurricane Hunter data and surface observations,” Cangialosi said at 4 p.m.

On its Friday afternoon forecast track, the center of the storm would be over western Lake Pontchartrain by Saturday at 7 a.m.

Slight shifts to the east in the track of the storm’s center, and the lopsided growth of its thunderstorms well to the east of that center resulted in rainfall estimates being lowered several times on Friday, reducing the threat to areas to the west of New Orleans.

However, forecasters with the Slidell office of the National Weather Service warned that rainfall totals could be significantly greater in areas caught beneath heavier rain bands, and that even moderate rainfall could prompt evacuations or rescues in some locations. Some rivers and tributaries also could pose threats by topping their banks.

At mid-day, forecasters with the weather service’s Weather Prediction Center warned that as the storm moved ashore, areas beneath rain bands could see rainfall rates of as much as 2½ inches per hour, increasing the flash flood threat.

A flood advisory for the south shore was issued Friday evening after as much as 3 inches of rain had fallen on the New Orleans area. 

“The rainfall that is occurring over the city currently will likely be the heaviest this evening … We are expecting this to persist for the next hour maybe two,” NWS meteorologist Megan Williams shortly after the 7 p.m. update. “Rainfall rates are still looking like 1 to 2 inches per hour, and winds have been gusting at 30 to 40 mph, especially for areas along the lake.”

A tropical storm warning remained in effect from just east of Morgan City to the eastern border of Walton County, Fla. 

A flash flood watch remained in effect for much of southeast Louisiana until Sunday at 7 a.m., though the watch was lifted Friday at 3 p.m. for Baton Rouge and Ascension, Assumption, Livingston and St. James parishes.

Minor coastal flooding also was expected, with a coastal flood warning for 2 to 3 feet of water in effect from south of Houma to the mouth of the Pearl River and farther east along the Mississippi and Alabama coastlines. The warning extends through Saturday at 7 p.m.

Jefferson Parish Councilman Ricky Templet reported sporadic bouts of light rain Friday afternoon in Lafitte but no evidence of surge or tidal flooding.

A coastal flood advisory for 1 to 2 feet of tide and rainfall-elevated water was in effect for areas around lakes Maurepas and Pontchartrain until Saturday at 7 p.m.

Forecasters also warned that a tornado or two also could form as the storm moved ashore.

Areas to the west of Baton Rouge were expected to see fewer effects from the storm, with rain totals of only a half inch in Lafayette and only an inch in Lake Charles. 

New Orleans remained on alert for rain that might overwhelm the Sewerage & Water Board’s uncertain drainage capabilities. On Friday, the agency said 98 of 99 drainage pumps were ready for service, as well as two turbines and all five backup diesel generators. In recent months, the agency’s leaders have warned that the power supply to its drainage system was in a “fragile state,” and they announced last week that repairs to two turbines would take longer than previously expected. 

Still, the utility said it had enough power to run all of the necessary pumps.

New Orleans officials urged drivers to move vehicles to neutral grounds and other high locations by Friday at noon because of the threat of street flooding. Crews worked throughout the day to clear leaves and debris from catch basins and asked contractors to secure construction sites.

“This is a reminder that we are at the beginning of hurricane season, and now is the time to review emergency plans, gather emergency supplies, and stay informed,” City Hall said.  

Jefferson Parish officials said there would be no curbside garbage or recycling collection on Saturday; no makeup day was scheduled. Residents were urged to avoid putting bulky items out for collection until after the threat of the storm has passed.

Parish trash drop-off sites also will be closed Saturday but will reopen on Sunday.

St. Tammany Parish was typical of suburban parishes in opening sandbag filling locations to the public on Friday. Residents were asked to bring their own shovels to fill the 15-per-car limit of bags. 

The parish also closed several recreational sites at 5 p.m. “just out of precaution,” said Michael Vinsanau, a government spokesman. 

“We’re just kind of in a waiting game,” Vinsanau said. “We think this is just going to be a lot of rain, which we’re prepared for.”

Scott Lee, a spokesman for the St. Tammany Sheriff’s Office, said high water vehicles have been strategically placed around the parish in advance of potential “flooding, wind or whatever the case may be.”

An experimental mapping program operated for state emergency managers by Louisiana State University’s Coastal Emergency Risks Assessment laboratory indicated that, based on a Friday morning National Hurricane Center forecast track, a combination of rainfall and high tides were likely to cause some flooding in typical hotspots over the next few days, including the Interstate 12 interchange at U.S. 190 north of Mandeville and at several locations along Airline Highway in St. John the Baptist Parish. 

Gov. John Bel Edwards declared a state of emergency in advance of the storm on Thursday, a formality that triggers gives him extraordinary authority and triggers potential action by the Federal Emergency Management Agency and other federal agencies if immediate assistance or recovery funding is needed.

By early Friday, Edwards had activated the state’s emergency operations center and five coastal parishes had also issued emergency declarations. 

FEMA also was monitoring the weather system and had prepared for activation of various response teams if necessary.

As a precaution against contamination, the state Health Department closed all Louisiana oyster beds to harvesting beginning at sunset. The closure was to remain in place until health officials determine that waters comply with shellfish sanitation rules.

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Jessica Williams, Marie Fazio and Faimon A. Roberts III contributed to this report.