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Ex-Ida causing major flooding

Posted by Andy Johnson under Daily updates

Technically, the surface low pressure center of Ida that was tracked into South Carolina 2 days ago became absorbed by a secondary low that formed at about the same time that extratropical Ida was beginning to move off of the coast. The secondary low, however, was energized by all of the tropical moisture which it entrained.

The movement of the new Nor’easter has been very slow.  As a result, rain has been falling over the same areas for a long time. In addition, the large wind field from this system has been causing a long fetch right into Chesapeake Bay. Nearly record storm tides are being recorded in Virginia and Delaware. This stage of Ida is causing more damage and flooding than the original tropical stage. Norfolk, VA has been keeping tide records since 1927. Only two other systems, Hurricane Isabel in 2003 and the Chesapeake-Atlantic hurricane of 1933 have caused higher tides. Most of the Nor’easters at this latitude move more quickly and do no allow the building of coastal water due to a large fetch which ex-Ida has done. The Chesapeake Bay Bridge Tunnel and Cape Henry, VA both experienced wind gusts as high as 64 MPH.

At Sewell’s Point, VA, I have seen the tide as high as 7.6 feet above mean lower low water at 5:36 PM EST. This is approaching the 4th highest storm surge behind the Ash Wednesday storm on 1962, Hurricane Isabel in 2003, the April 11, 1957 Nor’easter and the 1933 Chespeake-Atlantic hurricane. If it continue to rise about 8.9 feet it would be the highest on record. The graph below shows the water level . The predicted astronomical levels are shown in blue and the actual in shown in red.

The satellite and radar images below show heavy rain and convection still moving ashore with the slow moving low pressure area. Rainfall totals in Virginia are up to 9.13″ at Jones Creek, 4.93″ in Newport News/Williamsburg International Airport, 4.71″ at Roanoke. The final rainfall total in Atlanta was 5.98″.