American Red Cross April 26, 2006 Michael Wyllie National Weather Service.

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

http://www.nhc.noaa.gov/gifs/peakofseason.gif

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



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




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


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


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


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!

American Red Cross April 26, 2006 Michael Wyllie National Weather Service.

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