NEW YORK — As Hurricane Irene roared through the Northeast — home to some of the country's most densely populated cities and costliest waterfront real estate — experts were forecasting a multibillion-dollar disaster.
The economic impact of the hurricane largely will depend on factors that include the storm's size, where it makes landfall as it jogs up the Eastern Seaboard, and the speed at which it's moving when it hits the major cities.
"It's probably going to be very damaging," said Roger Pielke, a University of Colorado professor and fellow of the Cooperative Institute for Research in Environmental Sciences.
A computer model of Irene's potential impact puts the estimated damage at $4.7 billion, according to research by Pielke and catastrophe-insurance provider ICAT. That figure, which came from analyzing 27 comparable storms dating back to 1913, includes destruction of homes, cars, public infrastructure and other property caused by high winds and flooding. The number doesn't factor in the added impact of lost sales from shuttered restaurants, quiet casinos, canceled flights and boarded-up stores.
On the less-severe side of ICAT's Irene model are East Coast storms that caused less trouble. In 1985, Gloria resulted in $2.5 billion in damage (adjusted to 2011) after it made landfall on Long Island, N.Y., as a Category 1 storm with 85-mile-per-hour winds. Hurricane Belle, which hit New York in 1976, caused just $570 million in damage, despite 90-mph winds.
The impact is expected to be significant for the nation as a whole because the major metro areas that will be affected, including New York City, Philadelphia, Boston, Baltimore and Washington, account for 16 percent of national economic output and 14 percent of total employment, according to Moody's economist Ryan Sweet.
"If damage is severe and disrupts production for several days, there will be a noticeable impact on the national economy for August," Sweet said. But he expects any lost output to be made up in subsequent months as construction firms go to work rebuilding and consumers replace damaged property, so he isn't revising his quarterly GDP growth estimate of 1.5 percent annualized.
Some retailers are getting a boost in business this week, but extreme weather like hurricanes is damaging to the retail sector as a whole. And this one is coming in the thick of the critical back-to-school shopping weekend, a time when some merchants make up to 25 percent of their annual revenue.
In fact, weather research firm Planalytics estimates that Irene will stop 80 million shoppers from hitting the malls this weekend. At the same time, demand for hurricane-related supplies is giving some retailers an unexpected boost that will likely continue as people deal with the post-storm cleanup.