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Rick Webre, Ascension Parish Homeland Security Director, at lectern, speaks about the impact that can be expected from Tropical Storm Barry as from left behind, Sorrento Mayor Mike Lambert, Donaldsonville Mayor Leroy Sullivan, Teri Casso, Ascension Parish Council (behind Rick Webre) and Ascension Parish Sheriff Bobby Webre attend a Ascension Parish Homeland Security Unified Command press conference Friday July 12, 2019, in Gonzales, La.

GONZALES — The Lamar-Dixon Expo Center will open 8 p.m. Friday as a temporary shelter for Ascension Parish residents who fear they will be "at risk" as Tropical Storm Barry passes by the Baton Rouge region this weekend, parish officials said.

[Update, 10 a.m. Saturday: Barry has been upgraded to a hurricane.]

The shelter opening was one of several preparations town, city and parish officials in Ascension's unified emergency command announced Friday less than 24 hour before Barry is expected to make landfall early Saturday as a Category 1 hurricane.

Parish emergency officials said Ascension residents should be prepared for "two cascading events": flashing flooding as Barry drops an expected 10 to 15 inches of ran or more and then backwater flooding in the parish's lower areas 48 to 72 hours afterward.

Rick Webre, Ascension homeland security director, said the level of flooding is expected to fall between the March 2016 floods and the far more severe August 2016 flood in the parish. 

"If you're old enough to remember the 1983 flood, it's somewhere in that range," Webre said during a news conference at the parish Courthouse Annex in Gonzales. 

The '83 flood was the bench mark flood in Ascension and the greater Baton Rouge area upon which Ascension had built is self-financed flood protection infrastructure. 

Several of those systems were overtopped in August 2016, including the Henderson Bayou floodgate and parts of the Laurel Ridge Levee along the far eastern edge of the parish. 

Projections released Friday night show the Amite River at Denham Springs reaching 41 feet Tuesday evening. The level is 12 feet above flood stage but more than 5 feet below the record level seen in 2016.

An important bench mark for flood levels in Ascension and lower Livingston parishes, the Amite at Port Vincent is expected to crest at 13.1 feet Wednesday, at a major flood stage. Flood stage for the river is 8 feet. By comparison, the river hit a peak of 17.5 feet at Port Vincent on Aug. 15, 2016.

Webre said that at this time, the parish's drainage infrastructure looks to be remaining intact but some experts warned that storm surge in Lake Maurepas could cause drainage and flooding problems for lower parts of Ascension, Livingston and St. James parishes in the days to come.

He said the initial flash-flooding is likely to be worst in the Panama Canal and Conway Bayou watersheds south of Gonzales and near Sorrento. Unlike other parts of eastern Ascension that count on mechanical pumps, those watersheds rely on gravity drainage and are affected by tides in Lake Maurepas. Some parts of Prairieville in the northern corner of the parish could also see flash flooding.

The backwater flooding is likely to affect the lower parts of eastern Ascension, including the St. Amant area. That area and other regions closest to the Amite River were hard hit in August 2016.

Unlike the August 2016 flood, Donaldsonville and other parts of west bank Ascension may be in line some of the more severe rains. They are closer to Barry's track than the east bank is. 

Donaldsonville Mayor Leroy Sullivan urged residents to be vigilant and prepared.

"Although, in 2016, flooding was minimal on the west bank, we want to make sure that we're still on high alert," he said. 

The officials also cautioned, however, that it's still unclear where the most intense rain would fall and what Barry's final track would be, all factors that Sheriff Bobby Webre said make the storm unpredictable.

Despite the repeated words of caution Friday and warnings to stay off the roads, Ascension Parish has not called for evacuations or enforced a curfew, as Iberville has, because officials didn't want to limit people's move with Barry so close.

In neighboring James Parish, local leaders have already issued a voluntary evacuation order and have Lutcher High School prepared to be opened as a shelter, if needed.

Entergy has also sandbagged around its power substations in Gramercy and Convent and added pumps to keep them from flooding, St. James officials added. 

Webre, the Ascension homeland security chief, said the shelter at Lamar-Dixon will be in the large Trademart building, a climate-controlled building that has served as a shelter through other major events, including Hurricane Katrina. The shelter is for parish residents only.

The shelter will also house large animals as it has in past events.

The parish expects to stop sandbagging operations at 9 p.m. as winds from Barry are expected in the parish by 1 a.m. Saturday.

Ascension Parish Council Chairwoman Teri Casso urged residents to finish up what they have to do Friday because it will be too late Saturday.

"We are as ready as we can possibly be for what we feel lie is still an unpredictable event," she said.

The officials urged residents to call the parish's Citizens Service Center at (225) 450-1200 if they need information or help, including transportation to the shelter. Emergencies should still call 911.

Email David J. Mitchell at dmitchell@theadvocate.com

Follow David J. Mitchell on Twitter, @NewsieDave.