In a way, it was the perfect flood.
Shifts in Isabel's winds, a timely high tide and something called the "slosh" effect all conspired early yesterday to produce some of the highest water levels ever recorded in communities around the Chesapeake Bay.
The bay flooding was almost entirely the result of tidal phenomena, and not the unexpectedly modest rain that accompanied the storm in Maryland.
Meteorologists said the high water broke or tied 70-year-old records in Baltimore, Annapolis and Washington, as it inundated streets along the Inner Harbor and Fells Point, communities in Eastern Baltimore County and towns on the Eastern Shore.
"It was just the right conditions, timing-wise, of the tide, the surge and winds changing around right at the right time, to push all that water in there," said meteorologist Steve Zubrick, of the National Weather Service's Sterling, Va., forecast office.
Many hurricanes and storms that affect the Chesapeake pass to the east of the bay, and their counter-clockwise circulation usually means that winds drive water out of the bay. But Isabel tracked to the west of the bay, and its winds were fated to push the water northward, filling the tidal creeks and rivers like overflowing bathtubs.
Forecasters had warned emergency management officials on Tuesday that the approaching storm would produce tidal surges along the western shore of the Chesapeake.
"We were briefing people that even a Category 1 or 2 hurricane taking the right track can give you pretty high water levels," Zubrick said. "It doesn't have to be a real spinner."
But the size of the mound of water Isabel's winds actually piled up - 2 feet higher than predicted - surprised everyone.
"It's not an exact science," said Barbara Watson, who is the warning coordinator at Sterling.
"We're certainly further along than we were in 1954 when [Hurricane Hazel] came along," she said. But the Chesapeake Bay is such a complex natural system, and there have been so few storms like Isabel to study, that "it's difficult to come up with the forecasts." Given that difficulty, she said, a two-foot error is "a pretty good forecast."
The high tide in Baltimore was supposed to occur at 2:07 a.m. But that hour came and went, Zubrick said, and the water "was just going up and up."
It didn't stop rising until 8:06 a.m., according to Lt. Kevin Slover, of the National Hurricane Center's storm surge unit. By that time it stood at 8.15 feet above mean low water, or 7 feet above normal.
