Hurricane Ida - August 27-September 4, 2021
- ️David Roth
A tropical wave emerged off the African coast on August 14th. It was weak and
moved westward through the monsoon trough in the
eastern Atlantic. Entering the trade winds of the central tropical Atlantic on
the 21st, it was associated with an elongated
area of convection which increased in coverage the system moved through the
Windward Islands on the 23rd. The thunderstorm
area interacted with a broad area of low pressure near the northern coast of
South America, bringing heavy rainfall to northern
Venezuela. Thunderstorms became more concentrated with the convective system
on the eastern side of the surface low in the
southwest Caribbean Sea. Turning north-northwest on the 26th as it rounded
the southwest side of the subtropical ridge,
thunderstorm activity became better organized and the surface low became well-
defined, with a tropical depression forming
that morning southwest of Jamaica.
A tropical depression moved northwest for the next few days, becoming a tropical
storm on the afternoon of the 26th.
The cyclone passed bt Grand Cayman on the 27th and as Ida approached the Isle of
Youth, it gained hurricane intensity
on the afternoon of the 27th. The center made landfall within the province of
Pinar del Rio that evening. Later
that night, Ida entered the southeast Gulf of Mexico. Land interaction and
southwest vertical wind shear led
to a halt to intensification during this time. As it moved farther into the'Gulf
of Mexico, intensification resumed
on the morning of the 28th and Ida became a major hurricane by the 29th while not
far offshore off Southwest Pass.
Ida moved ashore Port Fourchon during the early afternoon of the 29th as a strong
hurricane. Turning north-northwest,
Ida wouldn't start weakening until it moved out of the swamps of southern Louisiana.
The storm regained tropical storm
intensity as it entered southwest Mississippi early on the 30th. Then moving
northeast, Ida weakened to a tropical
depression in northeast Mississippi that afternoon. Ida accelerated northeast,
undergoing extratropical transition
in the Tennessee Valley and completing it as it moved into West Virginia on the
morning of September 1st. Turning
east-northeast, Ida strengthened somewhat and brought very heavy rainfall and
gale-force winds near coastal sections
of the northern Mid-Atlantic and southern New England states. Its center moved
across northern New Jerseyvand south of
Long Island by the morning of the 2nd before moving farther out to sea thereafter.
Heavy rains fell in association with Ida near its Gulf Coast landfall into the
Tennesse Valley and then again just
before its oceanfall as it moved offshore the northern Mid-Atlantic states. New
York City's Central Park measured
its wettest hour on record -- 3.47" between 7:51 and 8:51 pm on September 1, 2021.
Overall amounts in the northern
Mid-Atlantic States peaked just above 10". The graphics below show the storm total
rainfall for Ida, which used rain
gage information from the National Weather Service River Forecast Centers, Forecast
Offices, and CoCoRAHS.