Remember when gas spiked to $3-plus a gallon after Hurricane Katrina? By this time next week, that could seem like the good old days.

Weather and energy experts say that as bad as Hurricane Katrina hit the nation's supply of gasoline, Hurricane Rita could be worse.

Katrina damage was focused on offshore oil platforms and ports. Now the greater risk is to oil-refinery capacity, especially if Rita slams into Houston, Galveston and Port Arthur, Texas.

"We could be looking at gasoline lines and $4 gas, maybe even $5 gas, if this thing does the worst it could do," said energy analyst Peter Beutel of Cameron Hanover. "This storm is in the wrong place. And it's absolutely at the wrong time," said Beutel.

Michael Schlacter, chief meteorologist at Weather 2000, said Rita now appears most likely to hit between Port Arthur and Corpus Christi, Texas, sometime between Friday afternoon and Saturday morning.

Just about all of Texas's refinery capacity lies in that at-risk zone. (For a look at CNN.com's coverage of Hurricane Rita, click here.)

"There is no lucky 7-10 split scenario to use a bowling analogy," he said. "If you're [a refiner] within 200 miles, you're going to feel the effect."

Compounding Katrina's impact

When Katrina hit, 15 refineries, nearly all in Louisiana and Mississippi, with a combined capacity of about 3.3 million barrels a day were shut down or damaged, according to the Energy Department. That represented almost 20 percent of U.S. refining capacity.

Within a week, almost two-thirds of that damaged capacity had resumed some operations, according to the department. But four refineries with nearly 900,000 barrels a day of capacity are still basically shut down.

If Rita hits both the Houston-Galveston area, as well as the Port Arthur-Beaumont region near the Texas-Louisiana border, that could take out more than 3 million barrels of capacity a day, according to Bob Tippee, editor of the industry trade journal Oil & Gas Journal in Houston.

"Before Katrina, the system was already so tight that the worst-case scenario was for a disruption that took 250,000 barrels of capacity out of the picture. That would have been considered a major jolt," said Tippee.

"We're already in uncharted territory now. We can't project what happens from another shot the size of Katrina or worse."

Part of the problem is that skilled crews needed to make refinery repairs are already busy trying to fix the Katrina damage. That would extend recovery time from Rita.

"[Rita] could have a significant impact on supply and prices -- this really is a national disaster," Valero Energy (Research) CEO Bill Greehey in an interview with Reuters Tuesday evening.

Gas not the only concern

Problems could spread beyond the gas pumps.

Tippee said that natural-gas prices could see a further spike, since so many of the offshore platforms off of Texas produce natural gas, not crude oil.

And while gasoline imports have helped bring gas prices down from record highs, there isn't as much potential for heating-oil imports, he noted.

"Gasoline tends to obscure everything, especially since we aren't paying heating bills right now," said Tippee. "But we were already looking at a winter fuel problem. We're about to take another hit that will cause a lot of problems."

Schlacter said even the oil platforms off the Louisiana Gulf Coast, which are not likely to take a direct hit from Rita, could be affected by large waves churning up the Gulf of Mexico as the storm passes to the south. Waves of as much as 40 to 50 feet could hit the platforms off the Texas Coast, he estimated.

Tippee said that production across the Gulf is already being affected by oil companies pulling workers off platforms ahead of the storm. And it's not just domestic oil being interrupted.

The Louisiana Offshore Oil Port (LOOP), the nation's largest gateway for overseas oil, stopped accepting deliveries of its 1.2 million barrels of oil a day Wednesday afternoon due to high seas, LOOP spokeswoman Barb Hesterman told Reuters. She said the disruption was expected to be "for a short time."

But if Katrina is any guide, it could take several days after Rita passes for production to resume even at oil and gas platforms that escape damage.

"There were several days where if you could have gotten out to the platform, you could have started it back up, but you couldn't find the boats or helicopters you needed to get back to the platforms," he said.