UPDATE: Rita Course Shifts Slightly; Storm Now a CAT 4

While meteorologists are still not saying for sure where Hurricane Rita will touch down in the next 24 to 36 hours, a slight change in course during the day on Thursday and into the evening may spare both Houston and Galveston, Texas from a direct hit.

In the meantime, some 2 million people on the Texas and Louisiana coasts were attempting to evacuate Thursday. As Rita dropped to a Category 4 storm on Thursday, and may come ashore as a Category 3 or 2 storm late Friday or early Saturday, officials still warned that she will bring major winds and heavy rains to a wide portion of Texas and Louisiana.

In the wake of Hurricane Katrina, Rita also brought rain to already battered New Orleans, sparking fears that the city’s damaged levees would fail and flood the city all over again.

As of 11 p.m. EDT, Rita was centered about 350 miles southeast of Galveston and was tracking at near 10 mph. Its winds were 140 mph, down from 175 mph earlier on Thursday.

The cities of Galveston and Houston, Texas, were under evacuation orders, with officials requesting people move further inland. Millions began streaming northward on Wednesday. The normal 45-minute drive from Galveston to Houston became a five-hour commute. Interstate 45 heading north out of Houston was turned into an outbound-only evacuation route by state officials. Travel time to Austin from Houston, normally a three-hour or less drive, was reported to take as much as 19 hours by Thursday.

Texas Gov. Rick Perry has requested residents from Corpus Christi to the Beaumont area voluntarily evacuate immediately. Texas National Guard troops that were in Louisiana helping with the Hurricane Katrina recovery efforts, returned home to the Lone Star State to help prepare for Rita’s visit.

Some 1.3 million people were ordered to clear out along the Gulf Coast, particularly in New Orleans and Galveston. As New Orleans continues to clean up from Katrina’s deadly visit in recent weeks, weary residents who had just returned to find out if they had anything left, were told they could be in danger again. Rain bands began lashing New Orleans early Thursday morning, increasing fears of more flooding if the patched of levee system fails again.

While Rita is expected to steer well clear of a direct hit on New Orleans, the New Orleans Times-Picayune reported that engineers are warning that the weakened levees can “only handle up to 6 inches of rain and a storm surge of 10 to 12 feet.” Forcasters are predicting rainfall amounts of between three and five inches, the Times-Picayune reported.

A Category 5 hurricane is the highest on the scale, with winds topping 155 mph and a storm surge usually more than 18 feet above normal. It leaves behind total roof failure on many houses and buildings and complete destruction of some other structures and mobile homes.

Galveston is no stranger to deadly hurricanes. A hurricane in 1900 that struck the city killed more than 6,000 people.