Tropical Storm Francine forces evacuations along Gulf Coast

(CNN) — The first evacuations have been ordered along the Gulf Coast as Tropical Storm Francine gains strength ahead of an expected hurricane strike by midweek, and a hurricane warning has been posted for Louisiana in anticipation of Francine’s arrival.

The storm was churning in the record-warm western Gulf of Mexico after forming late Monday morning a few hundred miles away from the Mexico-Texas border. Its maximum sustained wind speeds moved from 50 mph in the late morning to 65 mphby Monday night– just 9 mph shy of becoming a hurricane.

Flooding rainfall, strong winds and dangerous storm surge are likely this week along the western Gulf Coast as Francine continues to strengthen. Tropical storm and hurricane watches have been issued in the region as a result.

Along with the hurricane warning in Louisiana, tropical storm warnings and watches have been posted along portions of the Louisiana and Texas coast and a storm surge warning has been issued from High Island, Texas, to the mouth of the Mississippi River.

The hurricane center is now forecasting more significant strengthening in the next 36 hours, and the system could become a hurricane as early as Monday night and reach Category 2 ahead of its expected landfall Wednesday.

As of about 10 p.m. CT Monday, the center of the storm was 125 miles south-southeast of the mouth of the Rio Grande near Brownsville, Texas, moving at about 5 mph, according to the National Hurricane Center. It is expected to accelerate Tuesday.

Francine’s formation follows a rare quiet period in the Atlantic, with no named storms forming since Ernesto in mid-August, during what are typically some of the busiest weeks of hurricane season.

While the storm is zeroing in on a possible Louisiana landfall, it’s still too early to pinpoint exactly where it could cross into the state and how strong it will be at the time. The storm could strengthen quickly over very warm water – a symptom of a planet warming from fossil fuel pollution – that essentially acts as jet fuel for tropical storms. It could also end up stronger than currently forecast.

Louisiana officials are already bracing for impact from the storm’s dangerous flooding and storm surge. Gov. Jeff Landry issued a statewide declaration of emergency and has been in touch with the Federal Emergency Management Agency to prepare resources, he said at a Monday news conference.

“We want the citizens of the state not to panic, but to be prepared,” he said. “These storms are storms we unfortunately have been susceptible to each and every year, and hurricane season is upon us.” He also encouraged residents to pay attention to warnings from local officials.

There is a possibility the expected hurricane will be a Category 2 at the time of landfall and officials are expecting 7 to 9 inches of rain over a 12-hour period, said Jacques Thibodeaux, director of the governor’s Office of Homeland Security and Emergency Preparedness.

Mandatory evacuations were ordered for parts of Louisiana’s Cameron Parish, according to an official’s social media. Both mandatory and voluntary evacuations were ordered farther east in Jefferson Parish’s town of Grand Isle. In Mississippi, voluntary evacuations also began in the city of Pass Christian.

Some parishes, including St. Mary and Terrebonne, started to close off floodgates and distribute sand bags Monday. Terrebonne Parish also declared a state of emergency, according to a news release.

Francine could become a hurricane by Tuesday night a few hundred miles east of the Texas coast and is expected to strengthen up until landfall on Wednesday evening.

Tropical storm-force winds could reach parts of far northeast Mexico and far southern Texas by Tuesday. Ahead of that, storm surge and rough surf could cause minor coastal flooding on the Mexico coast early this week.

The storm’s worst rain and wind will likely begin by Wednesday morning, but storm surge concerns will ramp up for the US as the system strengthens and as it nears landfall.

A storm surge watch was issued Monday for coastal areas of far eastern Texas through Louisiana and Mississippi. Parts of the central Louisiana coast could endure the worst storm surge, with levels potentially reaching up 10 feet above normal.

Heavy rain will also be a serious threat, particularly in coastal areas of northwest Mexico Monday. The system’s heavy rain could also begin in far southern Texas Monday before reaching more of the western Gulf Coast Tuesday.

Tropical downpours from the system will bring 4 to 8 inches of rain from far northeast Mexico to parts of the Texas coast and southern Louisiana this week. Totals could come close to a foot for areas stuck under persistent downpours. A more widespread 2 to 4 inches is likely across the region.

Texas will get most of its heavy rain early this week, but some of the most torrential conditions could hold off until late Tuesday night for Louisiana.

Tropical rainfall could lead to a “considerable” risk of flash flooding, according to the NHC.

A level 3 of 4 risk of flooding rainfall is in place Wednesday for much of Louisiana and parts of southern Mississippi, according to the Weather Prediction Center.

The system in the Gulf isn’t the only area of stormy weather that could cause tropical trouble.

Two other areas in the open Atlantic have a medium chance of developing in the next seven days, according to the NHC. Any possible tropical system from either is still days away from developing, so it’s far too early to speculate on where they could end up.

CNN Meteorologists Gene Norman, Elisa Raffa, Allison Chinchar and CNN’s Ashley R. Williams contributed to this report.