Flooding from Harvey is expected to continue for days following the storm's final landfall in the United States.
Record-breaking rainfall has occurred in parts of Texas, including Beaumont, which has been drenched by more than 40 inches of rain between Aug. 26 and Aug. 29.
Shelters are swelling to capacity as hundreds of thousands of displaced people seek help following the storm. Water damage, mold and disease-ridden water will possibly render parts of Houston inhabitable for weeks and possibly months.
The number of people killed by the storm is also expected to rise as rescuers slowly begin to shift to the recovery phase in impacted areas. So far, Harvey has claimed the lives of at least 36 people.
Dr. Joel N. Myers, AccuWeather's founder, president and chairman, stated that Harvey will be "the worst natural disaster in American history."
10 photos that capture the utter devastation from Harvey
Harvey's shelter crisis: Where are the thousands of evacuees?
Rescuers work tirelessly to protect animals amid Harvey's calamity
Flooding catastrophe from Harvey to persist in Texas, Louisiana as locally severe storms erupt
7:00 p.m. CDT Thursday: Rescue efforts are still ongoing even though rain from Harvey ended days ago.
The US Coast Guard has rescued or assisted at least 6,000 people sting rescue efforts began. Some rescue teams have had to break through the roofs of houses to reach the people trapped inside.
People that may be in contact with flood waters should use caution as they can be dangerous and lead to illness.
"A Texas A&M University analysis of floodwater samples from the Houston area shows E. coli levels that are 125 times higher than is considered safe for swimming," the Associated Press said.
6:10 p.m. CDT Thursday: The threat of tornadoes will continue across parts of Tennessee, Alabama and Mississippi into tonight.
An emergency manager reported tornado damage near Mount Pleasant, Tennessee after a severe storm moved through the area earlier in the afternoon. Another storm capable of producing a tornado also tracked near Nashville, Tennessee.
5:40 p.m. CDT Thursday: Some gas stations near areas hit hard by Harvey are running out of fuel.
Price gouging has been reported in the Dallas Fort-Worth area as people line up to fill their cars with gas.
“The head of the Texas agency that regulates the oil and gas industry is urging people to wait three or four days to fill their cars and trucks with gasoline if they can,” the Associated Press said.
As of Thursday afternoon, there were 10 Gulf Coast refineries shut down, according to the Energy Department.
4:05 p.m. CDT Thursday: Several tornadoes have touched down in Mississippi, Alabama and Tennessee with thunderstorms associated with Harvey.
These tornadoes have lead to some damage, including bringing down trees and power lines in Booneville, Mississippi.
Meanwhile, Houston public schools have announced that classes will start on Sept. 11 due to Harvey. This is two weeks later than when school was originally scheduled to begin.
1:52 p.m. CDT Thursday: Major health risks could arise this weekend as temperatures will be in the lower 90s in the Houston area through Saturday. Combined with high humidity levels, it will feel rather uncomfortable, especially for those outside cleaning up after Harvey.
"Temperatures will be in the lower 90s in the Houston area [and] RealFeel® temperatures will be well into the 100s F during the afternoon. Air quality levels, largely due to ozone, will be unhealthy for sensitive groups," according to AccuWeather Meteorologist Jordan Root.
Those conditions could be particularly dangerous for anyone who remains stranded in flooded areas or without power in their homes.