Despite weakening back to a tropical storm after making landfall as a hurricane, Barry will continue to bring severe flood threats to the lower Mississippi Valley into Monday.
Barry moved inland near Intracoastal City, Louisiana, which is about 100 miles west of New Orleans, at midday Saturday. Barry briefly strengthened to a Category 1 hurricane with maximum sustained winds of 75 mph prior to landfall.
Power outages are mounting and water rescues have been performed as rain, gusty winds and storm surge flooding are lashing the central Gulf Coast. Water overtopped levees in Plaquemines Parish, in southeastern Louisiana, while flight operations have been shut down at the New Orleans International Airport.
The main threat from Barry will be how much rain is unleashed, even with the storm below hurricane strength this weekend.
Rainfall of 2-4 inches per hour can occur with Barry as it presses northward through the lower Mississippi Valley. Rainfall totals will average 10-18 inches with an AccuWeather Local StormMax™ of 24 inches possible in some places from Louisiana and western Mississippi to southeastern Arkansas.
Barry’s flooding rainfall to have much more impact than a typical Category 1 hurricane or tropical storm
In terms of impact, AccuWeather has designated Barry a level 2 storm on its RealImpact™ Scale for Hurricanes. The scale ranges from “Less than 1” to a 5, with 5 having the most severe impact.
“Our greatest concern is for torrential rain that would result in life-threatening flooding,” AccuWeather Hurricane Expert Dan Kottlowski said.
“Heavy, flooding rainfall is expected over a large area, especially over much of Louisiana into parts of western and southern Mississippi and southeastern Arkansas.”
“This is going to be a significant weather event,” Louisiana Governor John Bel Edwards cautioned in a post on Twitter. It is critical that you monitor updates and heed the advice of local authorities.” Edwards also announced that he’d authorized the Louisiana National Guard to activate up to 3,000 personnel to assist with Barry-related emergencies.
Edwards also implored residents to not attempt to drive on flooded streets and roads. Streets, highways and low-lying areas will be the first to take on water as torrential rain pours down. However, flooding will progress and expand as the storm moves slowly inland.
Significant rises on the secondary rivers in the region are likely with the risk of major river flooding including the Pearl, Black, Tickfaw, Comite, Amite and Tchefuncte.
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The Comite River near Baton Rouge, Louisiana, is expected to crest near record-high levels early next week.
Some portions of Louisiana experienced flooding as early as Friday afternoon, according to AccuWeather Extreme Meteorologist Reed Timmer, who was stationed near Chauvin, Louisiana, about an hour south of New Orleans.
Some secondary rivers, such as the Atchafalaya, generally do not contribute to the flow on the Mississippi in the delta region, but rather take water away from the main stem.
However, as heavy rain falls immediately over the lower part of the main stem of the Mississippi, a rise of a few feet can occur on that waterway. This will be especially true days later over the middle portion of the river, where larger tributaries gather rainfall.
Storm surge to flood coastal communities
Some rise in water is occurring along much of the upper Gulf coast, especially along the coast from Louisiana to Alabama.
“AccuWeather meteorologists expect a storm surge of 3-6 feet mostly along and just to the right of the storm’s path,” Kottlowski said.
Just east of where Barry made landfall, a tide gauge at Amerada Pass measured a storm surge of nearly 7 feet on Saturday afternoon.
Storm surge has exceeded 3 feet along the southern shores of Lake Pontchartrain Friday into early Saturday morning. Levels may rise 3-5 feet along the northwestern shores on Saturday.
On Saturday morning, AccuWeather Extreme Meteorologist Reed Timmer reported flooding along the Atchafalaya River in Morgan City, Louisiana, as Barry’s storm surge continued.
Water levels on the lower Mississippi River remain high from spring flooding that was still flowing downstream from the middle and upper part of the basin.
In comparison, the level on the Mississippi River prior to the arrival of Hurricane Katrina was 2 feet. On Thursday morning, the river level was just above 16 feet. Flooding in New Orleans occurred primarily as levees failed as a storm surge caused waters to rise in Lake Pontchartrain.
Earlier Friday, NWS hydrologists expected the Mississippi River at New Orleans to surge to near 19 feet. However, in a stroke of good news for locals, by Friday evening, they revised that forecast and now believe the Mississippi River will crest at 17 feet. Earlier in the week, hydrologists called for a 20-foot crest.
Levees in New Orleans are between 20 and 25 feet high at different points along the river, according to what Ricky Boyett, the spokesman for the Army Corps of Engineers in the New Orleans District, told The New York Times.
J. David Rogers, the lead author of a definitive 2015 study on the canal wall failures and catastrophic flooding of New Orleans following Hurricane Katrina in 2005, told AccuWeather in an interview that new levees installed in 2011 will provide the city with much better protection from major flooding.
“It’s a much more robust defense system that they have today with probably a 100-fold better site characterization than they had going into Katrina,” Rogers said. “You can’t even compare pre-Katrina to post-Katrina; it’s like comparing a biplane to a 747.”
Barry is bearing down on New Orleans after 6-10 inches of rain deluged New Orleans, which is below sea level, causing a flash flood emergency Wednesday. The pumps and elaborate drainage system could not keep up with rainfall rates of 2-3 inches per hour, resulting in serious street flooding and numerous high-water rescues.
Heavy rain that falls directly on the city poses the greatest threat for flooding in New Orleans.
With this storm, the amount of rain can overwhelm any city’s drainage system, let alone that of New Orleans.
Damaging winds, tornadoes and waterspouts all threats from Barry
While Barry strengthened into a Category 1 hurricane, sustained, hurricane-force winds of 74 mph or greater will only be possible in a small area near and northeast of the center.
However, with this particular storm being rather larger, bands of severe thunderstorms with tropical storm-force winds of 39 mph or greater can occur well away from the center and especially so on the eastern side of the storm.
Gusts of this magnitude have been lashing Houma, Louisiana, since Friday afternoon. So far, there has been a peak wind gust of 58 mph. A gust of 66 mph whipped Dulac, which is located along the southeastern Louisiana coast, at midday Saturday.
There is the ongoing potential for spin-up tornadoes and waterspouts up through a day or two after landfall in the region. Some of these may be wrapped in rain and difficult to see until they are already in the neighborhood.
Some of the oil and gas rigs in the Gulf of Mexico have been evacuated as a precaution, according to CNBC.
Barry to track northward over Mississippi Valley after landfall
The latest indications are that the storm will push northward over the lower Mississippi Valley later this weekend and then the Ohio Valley toward the middle of next week.
While the magnitude of rainfall will gradually diminish as the storm moves farther away from the Gulf of Mexico, the risk of flooding will continue along the storm’s path.
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