A storm surge watch, according to the National Hurricane Center means "there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours."
A hurricane watch, according to the hurricane center, means "hurricane conditions are possible within the watch area" usually within 48 hours.
The hurricane center says a tropical storm watch means "tropical storm conditions are possible within the watch area, generally within 48 hours."
The center of Delta made landfall at about 5:30 a.m. Wednesday along the northeastern coast of the Yucatan Peninsula, near Puerto Morelos, as Category 2 storm, according to the hurricane center.
As of 2 p.m. Delta - the earliest 25th-named storm ever to form - was located about 115 miles west of Cabo Catoche, Mexico, traveling northwest at 17 mph. It had maximum sustained winds of 100 mph.
Louisiana, Mississippi and a sliver of southeast Texas are in the forecast path. The track shifted away from Florida's Panhandle on Tuesday night.
In addition to life-threatening storm surge and dangerous winds, Delta is expected to inundate the region with up to 8 inches of rain, and up to 1 foot in isolated amounts along the northern Gulf Coast and lower Mississippi Valley, creating the potential for flash flooding and river flooding, according to the hurricane center.
Conditions could be conducive for prolonged flooding in the region.
Tropical-storm-force winds may reach the U.S. coast overnight Thursday.
During the day Thursday, swells could lead to "some coastal flooding at high tide in some low-lying areas, particularly in southern Louisiana," according to the Weather Channel.