1. Hurricanes

2. Tropical Cyclones
These are the greatest storms on Earth and are among the most destructive of natural disasters.
They are know by several names, depending on where they form.
Hurricane
Used in the Atlantic and eastern and central Pacific and is derived from the Carib Indian word “huracan” for the Carib god of evil.
Typhoon
Used in the western Pacific
Cyclone
Indian Ocean term
Willy Willy
Used in Australia (also “tropical cyclone”)

3. Naming Hurricanes Starting in 1953 Prior to 1953 Starting in 1979
NWS started using female names
Prior to 1953
Only the most severe hurricanes were given names
They were often named
For the place they did the most damage . . .
Galveston Hurricane of 1900
Or the time they hit . . .
Labor Day Hurricane of 1935
Hurricane of 1938 (Also called “The Long Island Express” or the New England Hurricane of 1938
Starting in 1979
Male and female names were included in lists for the Atlantic and Gulf of Mexico

4. Tropical Storm and Hurricane Names for the Atlantic, Gulf of Mexico, and Caribbean Sea
Letters Q, U, X, Y, and Z are not used because
there are few common names starting with these letters

5. Six Separate Lists
The names are used over again at the end of each six-year cycle.
Each calendar year starts with the next list, even if all the names weren't used the previous year.
One list is repeated every seventh year.
For example, in 2012 the 2006 list will be used again.
The exception will be if any names have been retired. The names of storms which have been extremely deadly and costly aren't used again.

6. The 2012 list will be the list used in 2006

7. More on Naming Hurricanes
If more than 21 named tropical cyclones occur in the Atlantic basin in a season
Additional names are taken from the Greek alphabet (Alpha, Beta, Gamma, Delta, Epsilon, Zeta, etc.)
If a storm forms in the off-season
The name used is based on the calendar year
Retiring Names
Whenever a hurricane has had a major impact, any country affected by the storm can request that the name of the hurricane be “retired” by agreement of the World Meteorological Organization (WMO)
This means it can’t be used for at least 10 years

8. Tropical Cyclone Characteristics
Form over tropical oceans between 5o and 20o latitude (except the South Atlantic and eastern south Pacific)
By international agreement, a storm is classified a hurricane if wind speeds are 74 mph (119 km/hour) and has a rotary circulation.

9. Hurricane Fran
Visible Image 9/5/96 FL
Cuba
Mature hurricanes average about 600 km (372 miles) across but can be up to about 1500 km (930 miles).
Pressure drops as much as 60 millibars from the outer edge to the center.
Steep pressure gradient generates rapidly spiraling winds which increase as the center of the storm is approached (due to conservation of angular momentum).
Duration: A week or more

10. The Structure of a Hurricane: Convective Rain Bands
Tropical moisture spiraling inward creates rain bands that pinwheel around
the storm center

11. The Structure of a Hurricane: The Eye Wall
As the inward rush of warm, moist surface air reaches
the center of the storm it rises in a ring of cumulonimbus towers.
It’s a doughnut shaped wall of intense convective activity.

12. Produces the most intense rainfall and greatest wind speeds
The Eye Wall
Produces the most intense rainfall
and greatest wind speeds
Katrina Eye Wall
Hurricane Charley

13. The Structure of a Hurricane: Outflow
Outflow prevents the convergent flow at lower levels from “filling in” the storm.

14. The Structure of a Hurricane: The Eye
Average Diameter is
20 to 30 miles (32 to 48 km)
A quasi-circular or quasi-oval region of light winds and skies that are clear to partly cloudy
and free of rain.
Caused by descending air that heats by compression, making it the warmest region of the storm.

15. Can you identify when the eye passed?
Wind speeds recorded by a data buoy in the eastern
Gulf of Mexico during the passage of Hurricane Kate (1985)

16. Hurricane Wilma October 2005
Eye
The record for the lowest surface air pressure for an Atlantic Hurricane,
882.0 mb, was recorded in the eye on Oct. 18

17. Vertical Section and Associated Patterns of Wind, Pressure, and Rain

18. Hurricane Formation and Decay
Cooperative Program for Operational Meteorology, Education and Training

19. Hurricanes are Huge Heat Engines
Fueled by latent heat released when huge quantities of heat are released by condensation.
Released heat warms the air making it buoyant (unstable).
Results in lower surface air pressure
Initiates a rapid inflow of air
Requires a large quantity of heat to get started.
Develop most often in late summer
Ocean temperatures 27o C (80o F)

20. Hurricanes Form in the Tropics
Often form in the ITCZ.
Few form poleward of 20 degrees latitude
Water isn’t warm enough
Not within 5 degrees of the equator
Coriolis force is too weak to initiate rotary motion

21. Tropical Disturbances
Africa
S. America
Originate in Africa as disorganized arrays of clouds and thunderstorms
Weak pressure gradient and little or no rotation
Most die out but some will develop rotation

22. Disturbances Can Become Easterly Waves
Streamlines (arrows) show low-level airflow.
East of the axis
Winds turn slightly poleward and converge forming clouds
Tropical Disturbances are associated with this side of the wave
West of the axis
Winds diverge
Clear skies
Can develop into a tropical depression

23. Trade Wind Inversions Prevent Development into a Tropical Depression
Subsiding air in a nearby subtropical high
Turbulence near the surface prevents lower level air from sinking
An inversion develops between the lower zone and the subsiding warmer layers above
This reduces the ability of the air to rise.

24. When Conditions Favor Hurricane Development . . .
No inversion exists and upper-level winds are not too strong
A Tropical Depression Forms
Pressure drops at center with a steep gradient
Surface winds strengthen and bring in additional moisture
Condensation releases heat and air rises
Further adiabatic cooling forms more clouds
Condensation releases more latent heat
Higher pressure develops aloft resulting in outflow
These processes continue and the storm forms.

25. Hurricane Allen (1980) loses strength as it moves over land.
Hurricane Decay
(1)
(2)
(3)
Hurricane Allen (1980) loses strength as it moves over land.
Hurricanes diminish in intensity whenever
They are deprived of the warm moisture needed for the source of latent heat by
Moving over land (roughness of surface also rapidly reduces wind speeds)
Moving over cooler ocean water
Large-scale flow aloft is unfavorable

26. Storm Tracks For 2005 - 28 Named Storms!
Influenced by
Trade Winds
Prevailing Southwesterlies
Jet Stream
Other Highs and Lows

27. Hurricane Destruction
Depends on
Strength of the Storm
Size and population density of the area affected
Nearshore bottom configuration

28. Damage to the roof of the Superdome from Hurricane Katrina
Wind Damage
Hurricane Andrew
Hurricane Wilma
The most obvious type of damage
Debris becomes flying missiles
Mobile homes are particularly vulnerable
High rise buildings, especially upper floors,
areVulnerable
Tornadoes that are produced by some
hurricanes contribute to the storms damage
Damage to the roof of the Superdome
from Hurricane Katrina

29. Hurricane Winds Storm surge will be greatest along the
coastline hit by the right side of the hurricane

30. Storm Surge The dome of water 65 to 80 km wide that sweeps
across the coast near the landfall position of the eye
The most devastating damage in the coastal zone
Responsible for 90% of hurricane-caused deaths
Cause:
Strong onshore winds push water towards the shore
Winds also create violent wave activity.
Low pressure on ocean surface is relatively insignificant

31. Storm Surge of the Galveston Hurricane of 1900
An unexpected Category 4 storm

32. Galveston Seawall

33. 25-Storm Surge From Hurricane Camille (1969)
Before
The Richelieu Apartments
in Pass Chistian, MS
After

34. Katrina Storm Surge and Flooding

35. Katrina Flooded an Estimated 80% of New Orleans in 2005

36. New Orleans

37. New Orleans Levees

38. Long Island Flooding Potential No Flooding

39. Long Island Flooding Potential Category 1

40. Long Island Flooding Potential Category 4

41. Saffir-Simpson Scale Based on study of past storms
Ranks the relative intensities of hurricanes
Established based on observed conditions.
Scale of 1 to 5
Category 1 is least severe
Category 5 is most severe
Rare
Not likely in the northeast because water temperatures are too cool.

42. Saffir-Simpson Scale

43. Category One Wind speed: Storm surge: Central Pressure: 980 mb Damage:
74-95 mph ( km/h)
Storm surge:
4-5 feet above normal
Central Pressure: mb
Damage:
Damage primarily to unanchored mobile homes, shrubbery, and trees along with some coastal road flooding and minor pier damage
Examples:
Allison, 1995; Danny, 1997

44. Category Two Wind speed: Central Pressure: Storm surge: Damage:
mph ( km/h)
Central Pressure: mb
Storm surge:
6-8 feet above normal
Damage:
Roofing, door and window damage to buildings; Considerable damage to shrubbery and trees, mobile homes, poorly constructed signs, and piers
Examples:
Bonnie, Georges, 1998

45. Category Three Wind speed: Central Pressure: Storm surge: Damage:
mph ( km/h)
Central Pressure: mb
Storm surge:
9-12 feet above normal
Damage:
Structural damage to small residences and utility buildings; foliage blown off trees and large trees blown down; mobile homes destroyed
Examples:
Roxanne, 1995; Fran, 1996; Rita, 2005.

46. Category Four Wind speed: 131-155 mph (210-249 km/h) Central Pressure:mb
Storm surge:
13-18 feet above normal
Damage:
Extensive damage to doors, windows and lower floors of shoreline houses; total roof failures on small residences; shrubs, trees, and all signs blown down; mobile homes completely destroyed
Examples:
Hugo, 1989, Luis, Felix, Opal, 1995, Emily, Katrina, Wilma 2005.

47. Hurricane Katrina A Category 5 over the Gulf of Mexico August 18, 2005
Came ashore as a category 4 storm
and 8 hrs later was still a Category 1

48. Category Five Wind speed: Central Pressure: Storm surge: Damage:
Greater than 155 mph (249 km/h)
Central Pressure:
<920 mb
Storm surge:
generally greater than 18 feet above normal
Damage:
Complete roof failure on many buildings and some complete building failures with small utility buildings blown over or away; severe and extensive window and door damage; mobile homes completely destroyed
Examples:
Camille, 1969; Gilbert, 1988; Andrew, 1992; Mitch, 1998

49. Atlantic Hurricanes that made Landfall as Category 5 Storms1
Name
Date
Landfall location
Fatalities
Dean
Aug. 21, 2007
Near Majahual, Mexico
At least 13
Gilbert
Sept. 1, 1988
Cancun, Mexico
327
Edith
Sept. 9, 1971
Nicaragua 30
Camille
Aug. 17, 1969
Mississippi, USA
256
Janet
Sept 28, 1955
Chetumal, Mexico
>600
Unnamed
Sept. 16, 1947
Bahamas 54
Labor Day Hurricane
Sept. 3, 1935
Florida Keys
408
Sept 5, 1932
No Records
San Felipe-Okeechobee Hurricane
Sept. 13, 1928
Puerto Rico
2,166
1 Since records began in 1886

50. The 20 Deadliest U.S. Hurricanes (1900 – 2005)

51. 1938 New England Hurricane – (The Long Island Express)
The storm was tracked as it moved west from Africa and toward the Bahamas Islands.
The U.S. Weather Bureau (now called the NWS)
Knew it was a powerful storm
It had reached category 5 strength on September 19
It was believed the hurricane would curve out to sea before reaching the Northeast.
The Bureau tracked the storm on the 21st as it was off the coast of Norfolk, V.A
Now a category 3 storm.

52. A large area of high pressure
Was located over the Atlantic Ocean just east of the coast
Kept the storm close to the coast and moving northeastward.
Charlie Pierce, a young research forecaster for the Bureau
Concluded that the storm would not continue to move northeast and curve out to sea but would instead track due north.
He was overruled by more senior meteorologists
The official forecast was for cloudy skies and gusty conditions –
but no hurricane

53. Instead of Curving Out to Sea…
The storm moved due north and accelerated in forward speed to 70 mph.
In the history of hurricanes, this is the fastest known forward speed recorded.
The incredible forward speed of the storm was 70 mph
Winds to the east of the eye are moving from south to north.
The same direction as the forward speed
Added to the already powerful winds. Eastern Long Island and New England would later be hit with wind speeds that exceeded 180 mph!

54. Landfall on LI on Sept. 21
The eye was about 50 miles across and the hurricane was about 500 miles wide.
3:30 PM which was just a few hours before astronomical high tide.
High tide was even higher than usual because of the new moon (spring tides).
Storm tides of 14 to 18 feet across most of the Long Island and Connecticut coast, with 18 to 25 foot tides from New London east to Cape Cod.
Caused enormous storm surge
High tides combined with winds gusting over 180 mph
Waves between 30 and 50 feet pounded the coastline with millions of tons of sea water, sweeping entire homes and families into the sea.
The impact of the storm surge was so powerful that it was actually recorded on the earthquake seismograph at Fordham University in New York City.
Downtown Providence, Rhode Island was submerged under a storm tide of nearly 20 feet.
Downtown Westhampton Beach, a mile inland, was under 8 feet of water!
Sections of Falmouth and New Bedford, Massachusetts were also submerged under as much as 8 feet of water.
Rainfall resulted in severe river flooding across sections of New York, Massachusetts, and Connecticut

55. Total Estimated Damage
700 deaths (50 on L.I.), 708 injured
4,500 homes, cottages, farms destroyed; 15,000 damaged
26,000 destroyed automobiles
20,000 miles of electrical power and telephone lines downed
1,700 livestock and up to 750,000 chickens killed
$2,610,000 worth of fishing boats, equipment, docks, and shore plants damaged or destroyed
Half the entire apple crop destroyed at a cost of $2 million

57. Long Island’s Coastline
Creation of Shinnecock Inlet
Moriches Inlet was widened
Affects the flow of sand along the coastline (longshore currents)
Depositional features
Erosional features

58. Shinnecock Inlet

59. Moriches Inlet
NASA satellite image

60. Detecting and Tracking Hurricanes Satellites

61. Aircraft Reconnaissance “Hurricane Hunters”
WC-130 Hercules
ER-2
USAF
NASA
WP-3D Oriion
Gulfstream G-IV
National Oceanic and Atmospheric Admin. (NOAA)

62. RADAR
Hurricane Andrew (1992)

63. Data Buoys

64. Hurricane Prepardness