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American Red American Red CrossCross
April 26, 2006April 26, 2006Michael WyllieMichael Wyllie
National Weather ServiceNational Weather Service
What is a hurricane?What is a hurricane?
A hurricane is a tropical cyclone. A cyclone is the general term for all circulating low pressure systems over tropical waters. In the Northern Hemisphere, cyclones circulate counterclockwise.
Katrina 2005
Hurricane Source Regions
Tropical Cyclone ProbabilitiesTropical Cyclone Probabilities
Atlantic Hurricane SeasonAtlantic Hurricane SeasonJune 1 – November 30June 1 – November 30
Early HurricanesEarly Hurricanes
August 1635 – probably had major August 1635 – probably had major effects on Long Island.effects on Long Island.
September 1815 – “The Great September 1815 – “The Great September Gale of 1815” – severe September Gale of 1815” – severe damage to south shoredamage to south shore
September 1821 – Crossed Long September 1821 – Crossed Long Island around Jamaica Bay – 21 lives Island around Jamaica Bay – 21 lives lost.lost.
High SeasThe Long Island Express, 1938High SeasThe Long Island Express, 1938
1938
Storm
Coastal FloodingHurricane Carol, 1954
Coastal FloodingHurricane Carol, 1954
Hurricane Donna
The eye apparently was enlarged to almost 100 miles in width as it approached the New York coast. Several stations on Long Island reported sustained winds over 100 mph, and gusts of 125-30 mph were recorded at the eastern end of the island
Hurricane Belle – August 8-10, 1976
Fiercest Part of a HurricaneFiercest Part of a Hurricane
The fiercest and most dangerous part of a hurricane is located in the 50 to 75 miles wide region surrounding the eye of the hurricane.
Hurricane HazardsHurricane Hazards
• High WindsHigh Winds• TornadoesTornadoesStorm SurgeStorm SurgeFlooding RainsFlooding RainsRip Currents, High Surf, Rip Currents, High Surf,
High Seas, and Battering High Seas, and Battering WavesWaves
100% GREATER AT 350 FEET
70% GREATER AT 200 FEET
50% GREATER AT 140 FEET
High-Rise Buildings at The Battery
Impact of Hurricane Wind Pressures at Various Altitudes
Source:“Minimum Design Loads for
Buildings and Other Structures”
ASCE 7-88, July 1990
100% GREATER AT 350 FEET
70% GREATER AT 200 FEET
50% GREATER AT 140 FEET
George Washington Bridge
Impact of Hurricane Wind Pressures at Various Altitudes
Source:“Minimum Design Loads for
Buildings and Other Structures”
ASCE 7-88, July 1990
Center Span Elevation of 213.0 feet (NGVD)
Goethals Bridge 140.0 feet
Bayonne Bridge 150.0 feet
Outerbridge Crossing 145.0 feet
Triborough Bridge 145.6 feet
Bronx-Whitestone Bridge 138.6 feet
Throgs Neck Bridge 145.6 feet
Henry Hudson Parkway Bridge 145.6 feet
Marine Parkway Bridge 57.0 feet
Verrazano-Narrows Bridge 230.6 feet
Williamsburg Bridge 133.0 feet
Manhattan Bridge 135.0 feet
Queensborough Bridge 135.0 feet
Center Span Elevations of Various New York City Bridges
HIGH LEVEL BRIDGE CLOSURES
Storm Forward SpeedHours Before Tropical StormWinds Occur at the Surface(Completion of Evacuation)
20mph 2 to 3 Hours
40mph 1 to 2 Hours
60mph 1 Hour or Less
The Wind effect on the The Wind effect on the Trees Trees
Last sustained winds over 60 mph was in Last sustained winds over 60 mph was in Hurricane Gloria in 1985 – 21 years ago, Hurricane Gloria in 1985 – 21 years ago, Bob in 1991 only affected eastern Long Bob in 1991 only affected eastern Long Island.Island.
Isolated severe thunderstorms have Isolated severe thunderstorms have thinned out dead trees in only a few thinned out dead trees in only a few areas. Much of the stands of trees over areas. Much of the stands of trees over NYC and Long Island have not been NYC and Long Island have not been stressed and will come down quickly.stressed and will come down quickly.
With sustained winds of 80+ mph and With sustained winds of 80+ mph and gusts at or above 100 mph, Gloria would gusts at or above 100 mph, Gloria would look like a walk in the park.look like a walk in the park.
TORNADOESTORNADOESNearly 60% of the hurricanes that Nearly 60% of the hurricanes that
made landfall between 1948 & made landfall between 1948 & 2004 spawned at least one 2004 spawned at least one tornado. In 2004 the storms set tornado. In 2004 the storms set records! In 2005 Hurricane Rita records! In 2005 Hurricane Rita moved into 6moved into 6thth place with the place with the number of tornadoes it spawned!number of tornadoes it spawned!
Most of these occurred in the Most of these occurred in the right front quadrant of the storm.right front quadrant of the storm.
Storm SurgeStorm Surge
It is the abnormal rise in water It is the abnormal rise in water caused by the wind and caused by the wind and pressure forces of a hurricanepressure forces of a hurricane..
Through history this has been Through history this has been the greatest hazard from the the greatest hazard from the hurricane and has been the hurricane and has been the greatest cause of fatalities, greatest cause of fatalities, although this is changingalthough this is changing..
Shelf SlopesShelf Slopes
Storm Surge
Shallow shelves result in higher surges Shallow shelves result in higher surges and lower waves: New York Cityand lower waves: New York City
Steep shelf's result in lower surges Steep shelf's result in lower surges and higher waves: Eastern Long and higher waves: Eastern Long Island Island
Gentle Shelf Incline Steep Shelf Incline
SLOSH does not incorporate SLOSH does not incorporate the effects of:the effects of:
Rainfall amounts.Rainfall amounts.
River flow.River flow.
Wind driven waves.Wind driven waves.
Heights of Heights of astronomical tides.astronomical tides.
Hurricane Angle of ApproachHurricane Angle of Approach
6.6
6.4 9.1
9.3
7.8
9.0
10.4
10.0
10.3
10.5
10.1
7.5
8.2
7.9
6.3
6.5
6.1 6.2
Storm Surge Elevations (in feet) ~ Category 1
15.6
11.2 14.0
15.2
15.1
14.8
15.7
16.0
15.7
16.6
15.8
17.2
15.0
11.7
11.5
11.3
13.0 15.7
Storm Surge Elevations (in feet) ~ Category 2
Jamaica Bay
Belt Parkway
Howard Beach
Rockaway Boulevard
Rosedale
Cross Bay Boulevard
Aqueduct Raceway
Jamaica Bay
Belt Parkway
Howard Beach
Rockaway Boulevard
Rosedale
Cross Bay Boulevard
Aqueduct Raceway
24.5
15.7 20.4
20.9
21.0
20.0
22.3
22.0
22.8
23.9
22.4
20.5
17.7
14.9
17.3
16.6
14.8 25.0
Storm Surge Elevations (in feet) ~ Category 3
31.2
20.8 26.6
27.0
27.4
25.2
27.6
26.7
28.0
28.7
25.6
30.8
28.1
18.1
22.2
22.2
24.6 31.3
Storm Surge Elevations (in feet) ~ Category 4
New York City Slosh Values
Flooding RainsFlooding RainsExcessive Rainfall is likely when Excessive Rainfall is likely when
tropical systems make landfall.tropical systems make landfall.The forward speed of the storm The forward speed of the storm
plays a big role in the amount of plays a big role in the amount of precipitation that falls.precipitation that falls.
Examples: Agnes in 1972, Floyd Examples: Agnes in 1972, Floyd in 1999, Ivan and Jeanne in 2004.in 1999, Ivan and Jeanne in 2004.
Flagler Beach, FloridaFlagler Beach, Florida FLAGLER BEACH, FLORIDA
HIGH SURF
WEAK SIDE - CAT 3
Battering WavesHurricane Carol, 1954
Battering WavesHurricane Carol, 1954
What About the Beaches?What About the Beaches? We have had three severe winters followed by a We have had three severe winters followed by a
relatively mild one in the Northeast.relatively mild one in the Northeast. Many of our dune structures are badly diminished Many of our dune structures are badly diminished
or totally gone compared to what protected us in or totally gone compared to what protected us in 1985 when Gloria hit.1985 when Gloria hit.
Some communities have replenished the beaches Some communities have replenished the beaches on their own.on their own.
Some have received natural replenishment. In Some have received natural replenishment. In other areas there is no beach left at all.other areas there is no beach left at all.
Much of the missing dunes and beaches are a Much of the missing dunes and beaches are a result of the disastrous nor’easters during the result of the disastrous nor’easters during the 1990’s as well as last three winters…we still 1990’s as well as last three winters…we still haven’t recovered.haven’t recovered.
Necessary Ingredients for Necessary Ingredients for HurricanesHurricanes
Warm Tropical WaterWarm Tropical WaterSea surface temps above 27 degrees Sea surface temps above 27 degrees
Celsius/80 degrees FahrenheitCelsius/80 degrees FahrenheitTropical WaveTropical Wave
Seedling storms move off the coast of AfricaSeedling storms move off the coast of AfricaHigh Pressure AloftHigh Pressure Aloft
Upper atmosphere highUpper atmosphere highEasterly or Weak Westerly Upper Easterly or Weak Westerly Upper
Level FlowLevel Flow
REWIND…
The hurricane season of 2005!
REWIND…
The hurricane season of 2005!
One for the record books!
27(8) named storms!
One for the record books!
27(8) named storms!
Why did we have Why did we have so many storms?so many storms?
The hurricane’s energy source – warm ocean sea surface temperatures -- were above average!
Weak El Nino or neutral conditions occurred during all of the 2005 hurricane season.
Weak El Nino or neutral conditions meant weak vertical shear over the tropical Atlantic. This resulted in conditions favorable for development and strengthening.
What Happened?What Happened?
27(28) Named Storms (Zeta) – 27(28) Named Storms (Zeta) – RECORDRECORD -There was actually another storm!-There was actually another storm!
10 is Normal10 is Normal
15 Hurricanes15 Hurricanes
6 is Normal6 is Normal
5 Retired Hurricane Names5 Retired Hurricane Names
Dennis, Katrina, Rita, Stan, and WilmaDennis, Katrina, Rita, Stan, and Wilma
The 2005 Hurricane SeasonThe 2005 Hurricane Season
But the number of But the number of storms is not the storms is not the only issue…it also only issue…it also counts on where counts on where the storms hit!the storms hit!
On average, 1 out of every 3 major hurricanes that develops hits the United States.
Between 1995 and 2003, thirty-two major hurricanes formed,...
...but only 3 major hurricanes - - Opal (1995), Fran (1996), and Bret (1999) - - made landfall during that time!
In 2004, the “Law of Averages” began to catch up with us as 3 out of the 6 major hurricanes made landfall.
In 2005, 5 out of 7 of the major hurricanes made landfall. Let’s hope this trend doesn’t continue!
Tracks of Major Hurricanes Making Landfall on the U.S. East Coast
Tracks of Major Hurricanes Making Landfall on the U.S. East Coast
INACTIVEPERIOD
INACTIVEPERIOD
ACTIVEPERIOD
ACTIVEPERIOD
If Global Warming affects sea surface temperatures can it therefore affect hurricanes???
Mean Decadal Temperatures Mean Decadal Temperatures for Central Park 1870-2005for Central Park 1870-2005
49
50
51
52
53
54
55
56
1870-79
1880-89
1890-99
1900-09
1910-19
1920-29
1930-39
1940-49
1950-59
1960-69
1970-79
1980-89
1990-99
2000-05
Therefore, you would think that global warming would cause more hurricanes…RIGHT!
But…wait just a minute!
What else is coming into play What else is coming into play here?here?
THE MULTIDECADAL CYCLE!!!!!
ACTIVE ACTIVE INACTIVE INACTIVE ACTIVE ACTIVE ACTIVE ACTIVE INACTIVE INACTIVE ??
A dilemma in the science of hurricanes today…is it Global Warming or the Multidecadal Cycle???
The meteorology community is stymied!!!!
One thing for sure…we must be prepared for more and stronger hurricanes for the next several years!
Not to sound the alarm too soon but we are also in a weak La Nina situation in the Pacific.
This means that we expect WEAK SHEAR over the tropical Atlantic Basin at least through the beginning of the Hurricane Season.
Dr. William Gray and his Hurricane Forecasters from Colorado State are forecasting 17 named storms, 9 hurricanes and 4 majors storms this year!
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