For Northeast, Hurricane Irene poses a rare and very real threat
Tuulia
For Northeast, Hurricane Irene poses a rare and very real threat
Posted at 02:37 PM ET, 08/26/2011
By Andrew Freedman
Millions of people from Philadelphia northward to Maine are bracing for
what may be their closest encounter with a hurricane since at least
1991. Depending on the exact path and strength of Irene at its closest
pass, the storm has the very real potential to sock New Jersey,
Southeastern New York, Connecticut, Rhode Island, and Massachusetts with
the region’s fiercest hurricane or strong tropical storm in many years.
In fact, most New Yorkers have never seen a hurricane pass over or just
to the west of the city, a track that would bring a dangerous storm
surge into highly populated and pricey real estate.
Even if Irene loses some of its punch as works its way up the coast,
moderate to major impacts — including flooding, downed trees and
significant power outages — are still anticipated in the heart of the
urban corridor from Philadelphia to Boston, especially near and east of
I-95.
As detailed by New York City’s Department of Emergency Management, most
of the hurricanes that have caused damage in the city have passed east
of Manhattan, over Long Island or Southeast Massachusetts. There was a
hurricane that made a direct hit on Manhattan in 1821, however. That
example does not bode well:
“The tide rose 13 feet in one hour and inundated wharves, causing the
East River to converge into the Hudson River across lower Manhattan as
far north as Canal Street. However, few deaths were attributed to the
storm because flooding was concentrated in neighborhoods with far fewer
homes than exist today,” the city Web site states.
The deadly 1938 hurricane – the benchmark against which all New England
hurricanes are measured – passed about 75 miles to the east of New York.
Still, that storm, which made landfall as a Category 3 monster, managed
to kill 10 people in New York City. As the NYC emergency management Web
site notes: “The hurricane could have caused far more deaths and damage
if it passed closer to the five boroughs.”
The worst-case scenario for New York would involve Irene tracking over
or just west of the city at hurricane strength, since that would expose
the city to the greatest winds and storm surge on the storm’s eastern
side. If Irene tracks to the east of the city (crossing Long Island)
and/or as a strong tropical storm rather than hurricane, the winds in
the city would be weaker.
However, the storm will still push a large wall of water up the East
Coast. As early as last night, the New York City office of the National
Weather Service was warning of “A DANGEROUS...LIFE THREATENING STORM
SURGE MAY EVEN BE POSSIBLE SUNDAY EVENING... ESPECIALLY IF THE SURGE
COINCIDES WITH HIGH TIDES...WHICH ARE RUNNING HIGHER THAN USUAL DUE TO
THE NEW MOON ON FRIDAY.” While Irene has weakened a bit since, the NYC
NWS office is still calling Irene “LARGE AND DANGEROUS” with the worst
of it likely late Saturday night into Sunday afternoon:
“THERE IS INCREASING CONFIDENCE IN TORRENTIAL RAINS DEVELOPING OVER THE
REGION SAT NIGHT AND CONTINUING THROUGH MUCH OF SUNDAY BASED ON THE NHC
FORECAST TRACK FOR HURRICANE IRENE. A PRECURSOR LOCALLY HEAVY RAINFALL
EVENT COULD TAKE PLACE SAT IN THE VICINITY OF A NORTHWARD DRIFTING
REMNANT FRONT WELL BEFORE THE ARRIVAL OF VERY HEAVY RAINS ASSOCIATED
WITH THE HURRICANE ITSELF. STORM TOTAL QPF OF 5 TO 10 INCHES IS LIKELY
FOR MUCH OF THE REGION...WITH LOCALLY UP TO 15 INCHES DEPENDING ON THE
EXACT TRACK OF THE STORM.”
Many parts of New York City and nearby parts of New Jersey are extremely
vulnerable to coastal flooding, including parts of Brooklyn, Queens,
Lower Manhattan and Hoboken, N.J.
The storm surge will be a key concern in other highly vulnerable parts
of Southern New England, from Long Island to Maine. Anyone who has ever
taken an Amtrak train between Washington and Boston has seen the
low-lying portions of the Connecticut and Rhode Island coastlines, and
the many homes that sit along the shore there.
Boston and Providence are other major urban areas at high risk of seeing
hurricane-force or high-end tropical storm-force winds and coastal
flooding, again depending on the exact track, strength and timing of the
storm. Like New York, there are many parts of the Boston metro region
that are susceptible to coastal flooding (including my hometown of
Swampscott, on the North Shore). If the storm tracks to the east of New
York City, but remains west of Providence and Boston, then the latter
two cities could receive the brunt of its strong winds, along with a
higher storm surge.
Historical Analogs
Some computer model projections take the storm on a path that would hug
the New Jersey coast, and head right up into the Big Apple, somewhat
similar to 1985’s Hurricane Gloria. Others suggest a track more
offshore, similar to 1991’s Hurricane Bob, which was the last hurricane
to make landfall in New England.
Hurricane Gloria made landfall on Long Island as a minimal hurricane
that was undergoing a transition to an extratropical storm system.
Despite traveling very quickly – much faster than Irene is projected to
move – Gloria still managed to drop very heavy rainfall along and to the
west of its path.
Hurricane Bob, a Category Two storm, raced from Buzzard’s Bay into the
Gulf of Maine, bringing the most severe impacts to Cape Cod and the
Islands, with significant wind damage all the way to Boston and the
Maine coast. Hurricane-force wind gusts were recorded in many areas east
of the Connecticut River. According to the National Weather Service,
Hurricane Bob caused $680 million in damage, and killed six people. Bob,
which was perhaps the most innocuously named hurricane on record, caused
a storm surge of 5 to 8 feet along the Rhode Island shore, and drove a
surge of 10 to 15 feet into Buzzards Bay. According to the Weather Service:
“The highest surges, of 12 to 15 feet, were observed in Onset, Bourne,
Mashpee and Wareham, at the head of Buzzard’s Bay. Cove Road, in
Mattapoisett, Massachusetts had 29 of 37 homes destroyed, while Angelica
Point, Massachusetts lost 32 of 35 homes along the shore.”
Every hurricane is different, so even though Irene’s path may end up
being somewhat similar to Gloria, Bob, or other storms of the past, its
effects are likely to be distinct.
For one thing, its wind field is expected to be more expansive than most
hurricanes and tropical storms as it approaches the coast, meaning that
even points well to the west of the eye can expect damaging winds. Also,
it is going to be moving slower than most storms do when they get this
far to the north, because the jet stream is located along the
U.S./Canadian border, and won’t be scooping this storm up and spitting
it out very quickly. This will allow Irene to drop copious amounts of
rainfall, which is something the mid-Atlantic states and New England do
not need right now.
In fact, inland flooding is the deadliest threat from hurricanes, and
Irene may, unfortunately, continue to demonstrate this. Areas that are
bracing for Irene have already seen an extremely wet August, with many
rounds of thunderstorms leading to urban and small stream flooding.
Philadelphia is going to set its record for the all-time wettest month,
having already set a new benchmark for its wettest August. Earlier this
month, New York’s JFK Airport set its all-time record for the wettest
24-hour period, when 7.8 inches fell Aug. 14.
The wet conditions mean that there is a greater likelihood for inland
flooding with Hurricane Irene than there otherwise would be, and it also
primes the region for significant tree damage from even just tropical
storm-force winds.
According to NWS forecasts, Irene is expected to dump nearly a foot of
rain along and to the west of its path as it moves up the eastern
seaboard and into New England. So even if the storm jogs east of New
York City, there still could be major flooding problems for the city and
surrounding areas to contend with.
By Andrew Freedman | 02:37 PM ET, 08/26/2011