Many have fretted that oil from the spill in the Gulf of Mexico could spread to the Florida Keys and then northward up the Atlantic. Now, the National Center for Atmospheric Research in Boulder, Colo. has come up with some computer modeling suggesting that the spill could extend along thousands of miles up the Atlantic coast as early as this summer.

The researchers at the center, a national lab sponsored by the National Science Foundation, stressed that their study was not a forecast and had not undergone scientific peer review. But they said their computer simulations offered a likely pathway for the dispersal of the oil if it entered the gulf’s so-called loop current, which circulates the waters in a clockwise pattern.

They said the current could propel the oil to Florida’s Atlantic coast within weeks, with the spill spreading as far north as Cape Hatteras in North Carolina by July or August before turning east.

The scientists used a dye tracer in a computer model to simulate how a liquid released at the spill site would disperse and circulate based on the best understanding of how ocean currents transport material under typical wind conditions.

William G. Large, director of climate and global dynamics at the center, said the timing of the spread of oil, whether as a thin film on the surface or mostly subsurface, would vary according to weather conditions and the state of the loop current, which he said was highly unpredictable.

The oil so far has washed ashore in Louisiana, Mississippi and Alabama, but officials along the eastern seaboard are watching developments closely. Even as far north as New Jersey, environmental protection officials have formed a special gulf spill response team to monitor the situation and develop a response plan.