After 10 days without a drop of rain in Baltimore, weather forecasters said yesterday that a tropical depression swirling over the Gulf of Mexico could provide Marylanders with a good soaking this weekend.
But that wouldn't end the region's drought emergency. Long-range climate predictions issued yesterday said the record-breaking drought in the mid-Atlantic states would persist through the fall.
The National Weather Service said Central Maryland would need to receive 9 to 12 inches of rain above the average to end the drought.
But "we'll take what we can get and be thankful for it," said Jim Travers, meteorologist in charge at the Sterling, Va., forecast office.
The tropical depression forming yesterday south of the Florida panhandle will become Tropical Storm Hanna if its sustained winds increase to at least 39 mph.
Heavy rain was falling in Florida, and the storm's center was expected to move north and reach central North Carolina by Sunday morning.
Rain should begin in Maryland late tomorrow and continue off and on into the early hours of Monday, "which is really what we want," Travers said.
An inch or two is expected in the Baltimore-Washington region as the storm moves north and east across the Delmarva Peninsula, with heavier rainfall near the center of the storm. Two to 4 inches of rain is possible along the Interstate 95 corridor if the storm veers to the west.
The water is needed badly. Baltimore's reservoirs have dropped below 45 percent of capacity, despite conservation efforts that have cut consumption by about 10 percent, according to the city Department of Public Works.
Stream flow and water tables remain at or near record lows across Central Maryland. The U.S. Geological Survey said wells in Baltimore, Harford and Montgomery counties have reached their lowest levels since record-keeping began in 1962, eclipsing the droughts of 1966, 1981 and 1999.
About 45 percent of the country is enduring moderate to severe drought.
In their national forecasts for the fall and winter, experts at the national Climate Prediction Center said yesterday that dry weather will persist through the autumn in the West, Northwest, Northeast, mid-Atlantic and Ohio Valley.
The El Nino effect
Noticeable drought relief for Maryland, if it comes, won't arrive until winter.
"The fall, we're saying, is more likely to be on the dry side from the Carolinas up through New England," said center director Jim Laver.
"That happens to be an El Nino signal," he said. El Nino conditions - the abnormally warm waters that have returned to the eastern tropical Pacific - influence weather patterns worldwide. In the autumn, he said, "they make storms go in a direction that is not favorable to us."
Winter should bring equal chances for normal or above-normal precipitation. "The drought will tend to move west of the Appalachians into the Ohio Valley," Laver said. "So we're looking for slow relief."
Although El Nino influences tend to double the number of East Coast winter storms, the climate center director could not say whether those storms would dump snow - something in scarce supply the past couple of winters - on Maryland.
"In the Baltimore-Washington area, they would tend to be rain rather than snow," he said.
Driest on record
The 12 months that ended last month were the driest September-through-August period in Baltimore since record-keeping began in 1871. Instruments at Baltimore-Washington International Airport logged only 63 percent of the average rainfall.
The accumulated 12-month rainfall deficit ranges from 11 to 16 inches across the Baltimore area.
The three months that meteorologists regard as summer (June through August) produced 8 inches of precipitation at BWI, making it the 20th- driest summer on record.
Summer temperatures averaged 76.9 degrees, no threat to the record of 79.1 set in the summer of 1943.
The year has brought 47 days with high temperatures of 90 degrees or higher at BWI. The average is 30 days; the record, set in 1988, is 54.