The National Hurricane Center is predicting the season’s first hurricane, to be named Barry, will develop over the Gulf of Mexico and strike the coast of Louisiana on Saturday.

The storm is predicted to be a massive rainmaker, unloading double-digit rainfall totals that will probably trigger serious inland flooding. Assuming it attains hurricane strength, damaging wind gusts are likely near where it comes ashore as well as a dangerous storm surge, which is a rise in water above normally dry land that can inundate homes, roads and businesses.


Visible satellite loop over Invest 92L. (NASA)

Louisiana Gov. John Bel Edwards declared a state of emergency on Wednesday, warning residents that “[t]his is going to be a Louisiana event with coastal flooding and heavy rainfall potentially impacting every part of the state. No one should take this storm lightly.”

Hurricane, tropical storm and storm surge watches have already been issued ahead of the storm affecting much of coastal Louisiana. The storm surge watch includes New Orleans, where levees protecting the city may be tested by ocean waters rushing up the Mississippi River raising water levels to historic heights Saturday.


(National Hurricane Center)

The responsible weather system originated over land and drifted from the southeastern United States into the open waters of the Gulf of Mexico on Tuesday. It is centered about 125 miles east-southeast of the mouth of the Mississippi River.

The warm gulf waters are feeding the rapidly organizing storm system, which is on the cusp of becoming a tropical depression. The Hurricane Center predicts the system will become Tropical Storm Barry by some time Thursday.

Even before earning a name, the developing storm was unloading heavy rain along the northern Gulf Coast from eastern Louisiana to the eastern Florida panhandle. Thunderstorms associated with the system dumped a half-foot of rain on New Orleans on Wednesday morning, prompting a flash flood emergency for the city.

The areas affected by rainfall will persist into the weekend and expand westward. In addition to New Orleans, places such as Mobile, Ala., Gulfport, Miss., and Baton Rouge are predicted to receive at least several inches of rain.

Through the end of the weekend, places farther inland like Montgomery, Ala.; Jackson, Miss., and Shreveport, La., are likely to see multiple inches of rain. Ultimately, some areas of Louisiana, near and just to the east of where the center of Barry is forecast to come ashore, could see 18 inches.

“Flash flooding and river flooding will become increasingly likely, some of which may be significant,” the Hurricane Center wrote. This is not welcome news for places along the already swollen and flooded Mississippi River.

Water, rather than wind, causes most of the fatalities in tropical weather systems.


Seven-day accumulated rainfall forecast. (NOAA/WPC)

Hurricane hunter flights are investigating the system. If a closed surface circulation is found along with the already-present, persistent, strong thunderstorms, it would get upgraded to a tropical depression.

The odds of Barry becoming the season’s first hurricane have increased noticeably since Tuesday as models have come into better agreement on its intensity, but there is a chance it peaks at tropical storm strength. Models also agree on the storm’s general timing: making landfall Saturday, although heavy rain and storm surge flooding are likely to begin before that.

While models show a range of possible track forecasts, the most likely landfall point is along the central or western Louisiana coast, but eastern Texas is not off the hook yet.


Five-day track and intensity forecasts from the 50-member ECMWF ensemble and the 20-member GFS ensemble. (weathernerds.org)

Irrespective of exactly where the storm makes landfall, storm effects from heavy rain and strong winds will expand well to the north, east and west of its track. Along the coast, the predicted storm surge of three to six feet above normally dry land could also extend considerable distances away from the center on the east side.