The National Weather Service shortly after 10 a.m. Wednesday issued a Tropical Storm Watch and Storm Surge Watch for the Texas coast, as forecasters predict a "100% chance" the low pressure system churning through the Gulf of Mexico will re-form as Tropical Storm Harvey.
Brazoria, Matagorda and Jackson counties are under a Hurricane Watch.
In their most recent forecast, forecasters warned Gulf Coast residents to prepare for 6 to 10 inches of rain across the region, with locally higher amounts, as well as a potential storm surge of 4 to 6 feet. Sustained wind speeds could reach 25 to 35 mph, with gusts up to 45 mph.
Scott Overpeck, a meteorologist with the National Weather Service office in League City, said Harvey is the most serious storm threat Houston has faced in 2017.
"We had Tropical Storm Cindy earlier, but that went more into Louisiana and was barely an issue," Overpeck said. "This poses a much greater risk because of the rainfall."
Harvey could make landfall as early as Friday morning, and due to its slow speed of around 10 mph, could cause extensive flooding as it inches inland. Continuous rain could fall across southeast Texas from Thursday through Tuesday.
If you like this story, consider signing up for our email newsletters.
SHOW ME HOW
You have successfully signed up for your selected newsletter(s) - please keep an eye on your mailbox, we're movin' in!
Models of the loosely organized storm vary, but all predict Harvey will make landfall between Corpus Christi and the Texas-Louisiana border. Overpeck said there is a small possibility that Harvey becomes a weak hurricane, but the greatest danger it poses is rain.
In June, Tropical Storm Cindy made landfall just east of Houston, near the Lousiana border. Yet Texas received little rainfall from the storm. That's because the wettest parts of Atlantic storms and hurricanes are their northern and eastern quadrants — which explains why Cindy caused flooding as far east as Alabama.
Forecasters predict Harvey will make landfall in Matagorda, putting Houston in line for pounding rains.
We will continue to cover Harvey as it approaches the Texas coast.