'Unsurvivable storm surge' threatens US as Laura explodes from Category 1 to 4 hurricane in 15 hours

NOAA hurricane hunter Nick Underwood captured video of the crew making one of five passes over Hurricane Laura on Wednesday.

“Central pressure dropped and wind speeds increased with each pass,” Underwood wrote on Twitter.

He also shared a time-lapse video of the crew’s fifth pass over Hurricane Laura.

Read his tweet and see the footage:

In addition to catastrophic storm surge, damaging winds and heavy rain, Laura will also likely produce several tornadoes and waterspouts.

"Hurricanes and tropical storms that make landfall in the Gulf of Mexico are more likely to produce tornadoes compared to storms in the Atlantic," explains Brandon Miller, CNN meteorologist.

Tornadoes are possible within the area shaded in red. 

But remember: Not all coastlines on the Gulf of Mexico are equally threatened.

"Note that this is less true for Texas landfalls in the Gulf — since the coastline angles more south to north like the Atlantic East Coast, rather than east to west like in the northern Gulf of Mexico coastline of LA/MS/AL/FL Panhandle," Miller clarified.

In other words, a tropical system that landfalls in Louisiana, which looks likely for Laura, could produce a few more tornadoes than a landfall in say, Galveston, Texas.

You can read more here.

Jefferson County, Texas, is imposing a curfew from 11 p.m. ET to 7 a.m. ET, according to the county's Office of Emergency Management.  

“During this curfew it will be unlawful for any person to be outside the confines of his residence, property or exempt areas," the curfew order by County Judge Jeff Branick says.

Portions of Jefferson County are already under mandatory evacuation orders.

The Emergency office warned residents: “A mandatory evacuation has been called. First responders will NOT be able to reach you for emergencies during the storm. Efforts to help after the storm will be severely limited.” 

If you're affected by Hurricane Laura, CNN wants to hear your stories.

When it's safe, text, iMessage or WhatsApp your stories to CNN at 347-322-0415.

A man relaxes in a beach chair as Hurricane Laura approaches the Gulf Coast August 25, 2020 in Galveston, Texas. Callaghan O'Hare/Getty Images

The small number of residents on Bolivar Peninsula in Texas were again warned to evacuate by Galveston County Judge Mark Henry.   

The judge said he was aware of about 40 residents that would be riding out the storm on the peninsula.

At a news conference, Henry said that it appeared that the worst will not hit his county, but he did warn that Bolivar Peninsula will likely be without power for days.  

Galveston County is located southeast of Houston, Texas. It has a population of over 340,000.

An LNG processing plant is seen in Cameron, Louisiana on August 26, 2020. Andrew Caballero-Reynolds/AFP/Getty Images

Hurricane Laura about 190 south of Lake Charles, Louisiana, according to the latest advisory from the National Hurricane Center.

Workers for the Southeast Louisiana Flood Protection Authority-West close floodgates in Harvey, Louisiana, just outside New Orleans, on Monday, Aug. 24, 2020. Gerald Herbert/AP

As Hurricane Laura closes in on the US, the Louisiana Coastal Protection and Restoration Authority is keeping a close eye on a total of 689 floodgates along their coastal zone.

As of this morning, at least 410 gates were closed, according to a post on the agency's Facebook page. 

Coastal Protection and Restoration Authority has spent several days closing pumps, sandbagging and re-enforcing gaps along waterways to get ahead of the storm.

The American Red Cross has deployed more than 600 disaster workers and sheltered more than 5,000 people last night, the group said in a release. 

The Red Cross told CNN yesterday that more than 700 workers were ready to respond. A spokesperson for the group says that the reason for the change was due to the new storm track, and that the number of workers in Louisiana and Texas remained the same. 

Satellite imagery of Hurricane Laura rapidly intensifying from midnight this morning until 2 pm ET. 

Starting the day, Laura was a Category 1 hurricane. It has now exploded into an extremely dangerous Category 4 storm. 

The storm had winds of 90 mph late Tuesday night, according to the 11 p.m. ET update. Laura did hit category 2 until the 2 a.m. ET update this morning.

Now, it is packing sustained winds of 140 mph with higher gusts. 

That is an increase of 50 mph in 15 hours.