Marylanders can expect plenty of wind and rain this weekend as the season's first big nor'easter spins up the East Coast.
With more than an inch of rain on the way, residents might be grateful it's still too warm to snow.
"These winter coastal storms are typically the track that produces the biggest winter snowstorms over the mid-Atlantic and New England states," said University of Virginia climatologist Robert E. Davis.
And there might be more.
Climatologists say this weekend's storm is likely the first in a series in the late fall and winter, thanks to moderate El Nino conditions that developed during the summer in the eastern Pacific Ocean.
The National Weather Service said yesterday that a low-pressure center was expected to develop by midday today over Florida, then intensify and move up the southeastern and mid-Atlantic coastline tomorrow.
One to two inches of rain are likely, producing some flooding in low-lying areas. Coastal communities could see gale-force winds, with seas 8 to 12 feet, heavy surf and some beach erosion.
No snow or ice is likely, according to meteorologist Dewey Walston, of the Sterling, Va., forecast office. But, in comments posted yesterday on the Sterling Web site, he said, "if this had been a month or so later ... well, we would have a problem."
The rain can only help Baltimore's reservoirs. They stood yesterday at 48 percent of their combined capacity, up from 41 percent at the depths of the drought. Loch Raven held almost 89 percent of capacity; Liberty was at 36 percent and Prettyboy at 24 percent.
"We'll get plenty of rain, all the way from the Gulf Coast to the Carolinas to New England," said Michael T. Eckert, senior branch forecaster at the National Weather Service. As nor'easters go, he said, "this is a strong one."
There is no precise definition for a nor'easter. "Part of it is weather lore and legend," said Davis, at the University of Virginia. But a nor'easter typically develops when a low-pressure center forms along the jet stream near the Gulf of Mexico, or off the Atlantic coast between Florida and Cape Hatteras, N.C.
Then it intensifies, and spins northeastward along the coast, drawing moisture and energy from the Gulf and from the warm Atlantic Gulf Stream. Barometric pressure drops, and strong northeasterly winds develop as it approaches, bringing gales and heavy precipitation.
When cold arctic air is entrenched east of the Appalachians, the precipitation may fall as snow, sleet or freezing rain.
The northeasterly gales and heavy surf can cause significant beach erosion and coastal damage. And an intense, slow-moving system can drop heavy snow or ice along the most densely populated region of the country, causing widespread disruption.
The worst nor'easters earn names.
The "Ash Wednesday Storm" in 1962 has been called the most intense nor'easter of the 20th century. Forty people died, and losses totaled $1.14 billion in today's dollars. Ocean City saw major damage from wind, water and beach erosion. Big Meadows, in the Virginia Blue Ridge, was buried in 42 inches of snow.
The "Presidents Day Storm," on Feb. 18-19, 1979, was the worst storm in 57 years in the Baltimore-Washington area. Up to 26 inches fell in Maryland, sometimes at rates of 2 to 3 inches an hour, with temperatures in single digits.
The so-called "Superstorm" of March 13-14, 1993 was felt from Florida through New England. It killed 200 people in tornadoes, coastal floods and snow-shoveling deaths. Western Maryland got 1 1/2 to 2 1/2 feet of snow. Baltimore got 12 inches. In the nor'easter's wake, Maryland taxpayers faced snow-removal costs totaling $22 million.
The last big nor'easter here was the "surprise" storm of Jan. 25, 2000. Instead of blowing out to sea, as forecast, the nor'easter turned up the coast. Blizzard conditions developed, with high winds and drifts up to 5 feet.
No one has predicted this will be a snowy winter in the mid-Atlantic states. But the National Oceanographic and Atmospheric Administration has warned of an increased frequency of Atlantic coastal storms - nor'easters - because of the development this year of moderate El Nino conditions in the tropical eastern Pacific Ocean.
Wayne Higgins, principal scientist at NOAA's Climate Prediction Center, said that El Nino shifts the course of the Pacific jet stream and the winter storms it steers across the United States.
During an El Nino, Pacific storms strike California instead of the Pacific Northwest. They track across the southern tier of states, pick up moisture from the Gulf, and turn northeastward up the East Coast.
"We are settling into the fall pattern you would typically see during an El Nino event," Higgins said. "It's wetter than normal in the Southeast, from Texas to Florida and into the Carolinas."
Higgins said the number of heavy snowstorms in the Northeast - with accumulations of 4 inches or more - can double during El Nino events, compared with La Nina periods, when the eastern Pacific is unusually cool.
Between 1950 and 1999, there were 30 such snowstorms during 12 El Nino events, and 16 during the last 12 La Ninas.