* These are just of few of the references available covering Tropical Cyclones, their effects on the Marine Industry and Marine Safety. *

Mariner’s Guide for Hurricane Awareness in the North Atlantic Basin (NOAA)

American Practical Navigator (Bowditch)

Port Heavy Weather Guide

Hurricane Havens Handbook for the North Atlantic (U.S. Navy)

REFERENCES

TROPICAL CYCLONE TROPICAL CYCLONE DEFINED!DEFINED!

A warm core, non-frontal, synoptic scale system with cyclonically rotating winds characterized by a rapid decrease in pressure and increase in winds toward the center of the storm. Cyclones develop over tropical or subtropical waters and have a definite organized circulation..

How do they develop?How do they develop?

Favorable environmental conditions that must be in place before a tropical cyclone can form:

– Warm ocean waters (at least 80°F / 27°C).

– An atmosphere which cools fast with height (potentially unstable).

– Moist air near the mid-level of the troposphere (16,000 ft / 4,900 m).

– Generally a minimum distance of at least 300 miles (480 km) from the equator.

– A pre-existing near-surface disturbance.

– Little vertical wind shear between the surface and the upper troposphere. (Vertical wind shear is the change

in wind speed with height.)

– Outflow aloft/exhaust

STAGES OF STAGES OF DEVELOPMENTDEVELOPMENT

Tropical Depression(TD): A tropical cyclone with wind speeds up to 33 knots. Identified by the letters “TD” and suffixed by a number (TD-01: the first tropical depression of the current calendar year.....TD-02, the second, etc...)

Tropical Storm (TS): A tropical cyclone with wind speeds 34 to 63 knots. Identified by names in alphabetical order consistent with formation date/time. (TS Arthur, Bertha...).

Hurricane: A tropical cyclone with wind speeds greater than 63 knots. Identified by the same name it had as a TS.

TROPICAL (EASTERLY) WAVE

No significant winds or seas

No defined near surfacecirculation

Identified by areas ofConvergence (thunderstorms)

TROPICAL DEPRESSION(Formative Stage)

Winds < 34 kts

Tropical wave develops a weak cyclonic circulation

Identified by thickening clusters of thunderstormson satellite

Central pressure falls rapidly below 1002mb if system intensifies

TROPICAL STORM(Immature to Mature Stage)

Winds 34 - 63 kts

Closed formation expands with spiral bands becoming better organized

Increasing sea state makes navigation near the center increasinglydifficult and dangerous

HURRICANE / TYPHOON / WILLY-WILLY(Mature Stage)

Winds > 63 kts

DANGEROUSLY HIGH SEAS navigation severely impaired

Radius of strong winds may exceed 350 NM

Gale Force Winds extend out further in right front quadrant (typically 120 NM)

TROPICAL CYCLONEStages of Development

1. Tropical Easterly Wave 3. Tropical Storm

2. Tropical Depression 4. Hurricane

Most damaging aspects of a hurricane:

AT SEA:

HIGH SEAS HIGH WINDS

INPORT:

STORM SURGE TORNADO/SVR TSTMS HIGH WINDS

HURRICANE CATEGORIES

Category 1 (Minimal) - Winds 64 to 82 knots, storm surge 4 to 5 ft above normal. No real damage to building Structures. Low lying coastal areas flooded, minor damage to piers. Examples Irene 1999 and Allison 1995

Category 2 (Moderate) - Winds 83 to 95 knots, storm surge 6 to 8 ft above normal. Minor damage to structures, poorly constructed buildings major damage. Coastal and low lying escape routes flooded over, considerable pier damage. Examples: Bonnie 1998, Georges (FL & LA) 1998 and Gloria 1985

Category 3 (Extensive) - Winds 96 to 113 knots, storm surge 9 to 12 ft above normal. Major damage to structures, poorly constructed building destroyed. Serious flooding along the coast, extensive flooding may extend inland 8 miles. Examples: Keith 2000, Fran 1996, Opal 1995, Alicia 1983 and Betsy 1965

Saffir- Simpson Scale

HURRICANE CATEGORIEScont.

Category 4 (Extreme) Winds 114 to 135 knots, stormsurge 13 to 18 ft above normal.Extensive roofing and windowdamage, complete destruction ofmobile homes. Areas above 10 ftflooded inland up to 6 miles, majorerosion of beaches, massiveevacuation of coastal areas.

(ANDREW 1992)

HURRICANE ANDREW DAMAGE MAP

Category 5 (Catastrophic)Winds above 135 knots, storm surge greater than 18ft above normal. Complete failure of roofstructures and very severe windowand door damage, some completebuildings fail. Major damage tostructures lower than 15 ft abovesea level, massive evacuations ofresidential units within 10 miles ofthe coast.

(CAMILLE 1969)

AUG 16, 1969

HURRICANE CATEGORIEScont.

Richelieu Apartments

The Power of a Category 5The Power of a Category 5“Hurricane Camille”“Hurricane Camille”

The Mansion

BEFORE!AFTER!

The map below shows where the seven basins noted for TC development are located and typical tracks for each. It also has the average number of tropical storms, and hurricanes, created in each basin.

TROPICAL CYCLONEFORMATION,

LOCATION

Hurricane Season Atlantic

01 June - 30 November

Eastern Pacific

15 May - 30 November

Western Pacific

Year round

TROPICAL CYCLONE FORMATION CONT.

2005 ATLANTIC TROPICAL CYCLONE

NAMES

LeeMariaNateOpheliaPhilippeRitaStanTammyVinceWilma

ArleneBretCindyDennisEmilyFranklinGertHarveyIreneJoseKatrina

Distribution of Surface Winds

Hurricane Andrew Strong CAT 4

Winds are very light in the eye, and increase rapidly in the eyewall. Fastest winds are found in the eyewall. Gale-force winds can extend 250-400nm from the center of the storm.

TROPICAL CYCLONECHARACTERISTICS

Feeder Bands (curved lines of convection) spiral inward to the Eye Wall. Some of the most violent weather (tornadoes/severe thunderstorms) occur in these areas

“Pumping Action” announces the approach of, and passing of the Tropical Cyclone

CloudsClouds

Most significant clouds are heavy Cumulus and Cumulonimbus

Spiral bands of CU/CB inward toward outer edge of eye

Cirrus changing to Cirrostratus and lowering, good indicator of approaching TC for the mariner

Cloud sequence similar to approaching warm front

TROPICAL CYCLONECHARACTERISTICS, CLOUDS

18AUG 15Z

19AUG 12Z

20AUG 12Z

970

975

990

985

980

995

10051000

1020

10151010

18Z 15Z21Z 00Z 03Z 00Z 03Z06Z 06Z09Z 15Z 18Z 21Z 09Z

MIL

LIB

AR

S

Isobars nearly symmetrical or elliptical in shape

Tightest isobaric gradient to right of storms line of movement

Central pressures well below average (890 – 940 mb not uncommon)

Barograph trace often shows “V” as eye passes (not something a ship wishes to see).

BAROGRAPH TRACEHurricane Bob 1991 Newport, RI

TROPICAL CYCLONECHARACTERISTICS, ISOBARS/PRESSURE

Time (UTC) Task / Event

00:00Synoptic time, cycle begins, receive aircraft fix (generally within +/- 00:30)

00:45Receive satellite fix data (TAFB, SAB, AFWA)

01:00 Initialize models

01:20Receive model guidance, begin preparing forecast

02:00NWS/DOD hotline coordination call (international coordination, if necessary)

03:00 Advisory package deadline

03:15 FEMA conference call

06:00 Next cycle begins

TPC/NHC Six-hour forecast cycle

Hurricane Isabel Track Guidance1800 UTC 10 Sep 2003

NOT-SO EXCELLENT! “HURRICANE KATE”

29 SEP 2003

BIG IMPROVEMENTS IN TC TRACK FORECASTS OVER RECENT DECADE, ESPECIALLY BEYOND 2 DAYS

UNDERWAYUNDERWAY A wise mariner needs to know what to do if warnings are in error (or plotted incorrectly), or they get caught unaware, and end up in the vicinity of a tropical cyclone at sea!

MONITOR THE STORM

National Hurricane Center issues warnings every 6 hours 0300Z, 0900Z, 1500Z, 2100Z

NAVTEX

SafetyNet

Annotated on weather facsimile charts

Private weather routing companies

E-mail List servers from the National Hurricane Center

1-2-3 Rule

WARNING’SWARNING’S Upon Receipt of Warning:

1. Plot the current and forecast 24 hour storm positions and forecast radius of 35 kt winds.

2. Using a compass extend the radius of the forecast 24 hour 35 kt wind area by 100 NM.

24 HR FORECAST POSITION CURRENT POSITION

135

NM

100

NM

WARNING’S, cont.WARNING’S, cont.

3. Draw tangents relative to the direction of the storm from the 35 kt radius (current position) to the outermost radius at the 24 hr forecast position. Avoid the DANGER AREA

100

NM

100

NM

24 HR FORECAST POSITION CURRENT POSITION

DANGER AREA

TANGENT

TANGENT

4. Use the same procedure for the 48 and 72 hr forecast positions, however, use 200 and 300 NM radii/respectively.

Avoid the DANGER AREA.

Current24 Hr48 Hr72 Hr

100 NM

100 NM

200 NM

200 NM

300 NM

300 NM

DA

NG

ER

AR

EA

DA

NG

ER

AR

EA

DA

NG

ER

AR

EA

WARNING’S, cont.WARNING’S, cont.

Meteorological elements are Meteorological elements are notnot uniformly distributed uniformly distributed throughout a tropicalthroughout a tropical

Storm is divided into Storm is divided into left/right semicircles and left/right semicircles and quadrants, relative to the quadrants, relative to the direction of motiondirection of motion

Usually strongest winds are Usually strongest winds are on right side in N.H. (added on right side in N.H. (added to motion)to motion)

TROPICAL CYCLONE EVASION

TROPICAL CYCLONE EVASION cont.

Storm’s location relative to own ship’s position:

Dangerous semi-circle: Wind greater due to wind augmented by the forward motion of the storm.

“Less Dangerous” semi-circle:

Wind decreased by forward motion of the storm.

Winds and seas forcevessel into path of storm.

Winds blow vessel away from storm track.

TROPICAL CYCLONE EVASION cont.

Ship in the “Dangerous” (right) semi-circle: 1. Maneuver ship so relative wind is from 045 degrees to starboard. 2. Continually hold course with respect to relative wind, making best way possible.

045 DEG REL

TROPICAL CYCLONE EVASION cont.

Ship in the “Less Dangerous” (left) semi-circle: 1. Maneuver ship so that relative wind is from 135 degrees to starboard. 2. Hold course with respect to relative wind, and make best SOA.

135 DEG REL

AHEAD OF CENTER (ON STORM TRACK)

Maneuver ship so that relative wind is 157 degrees relative, hold course and speed.

157 DEG REL

BEHIND CENTER (ON STORM TRACK)

Avoid center by best practical course (storm may recurve).

TROPICAL CYCLONE EVASION cont.

DO NOT CROSS THE “T” unless the ship is > 300 NM ahead of the storm and crossing right to left.

300 NM +

TROPICAL CYCLONE EVASION cont.

Never cross the “T”: Do not plan to cross the track of a hurricane.

NEVER LEFT TO RIGHT! Respect the negative effects that heavy weather places on vessel speed/handling. Sudden accelerations in hurricane motion can ultimately place a vessel in conditions not originally expected, resulting in disaster!

Adjustments to course & speed in order to remain clear of the danger area in a hurricane are the most prudent navigation decisions a mariner can make in these instances.

If it becomes necessary to cross the “T” right to left, ensure you are at least 300NM from the center.

Follow the 1 – 2 – 3 Rule

TROPICAL CYCLONE EVASION cont.

Monitor warnings and advisories to prevent an encounter.

Forecast Track Tendencies: Comparison of the most recent NHC forecast track with forecast tracks from the past 24 hours can be useful for determining a trend in the forecast motion of a hurricane.

For instance, a comparison of forecast tracks issued every 6 hours over the last 24 hours, may show a noticeable shift right or left (with respect to storm motion) in the forecast track of a hurricane. This information may provide some indication as to how the forecast & actual hurricane track are trending and provide more guidance in navigation planning for avoidance, particularly in the 2-3 day forecast range & beyond.

TROPICAL CYCLONE EVASION cont.

Assess your options: Plan Ahead. Never leave yourself with only a single navigation option when attempting to avoid a hurricane.

Sea room to maneuver is not a significant factor when operating in theopen waters of the North Atlantic, but becomes extremely important in theconfined waters of the Western Caribbean Sea/Gulf of Mexico.

More often than not, early decisions to leave restricted maneuver areasare the most sensible choice.

TROPICAL CYCLONE EVASION cont.

IN PORTIN PORT

MONITORING THE STORM

NHC Warnings/Bulletins

Local Radio / TV stations Port Authority / Coast Guard

Internet

CONDITIONS OF READINESS

CONDITION 5 - Destructive force winds (35 kts or as specified ) are possible within 96 hours.

CONDITION 4 - Destructive force winds are possible within 72 hours.Whiskey

CONDITION 3 - Destructive force winds are possible within 48 hours.X-Ray

CONDITION 2 - Destructive force winds are anticipated within 24 hours.Yankee

CONDITION 1 - Destructive force winds are anticipated within 12 hours.Zulu

These are the most common conditions of readiness.

Stay Inport or

Ride it out at Sea?

Factors to consider!Factors to consider! The decision to leave port for hurricane avoidance must be made very

early, and must be balanced with a number of other factors

- Storm Intensity, Size, Strength, and Speed. - Port Facilities, Berthing & Shelter Requirements - 24 hours prior to onset of gale force winds.- Probability of Hit (angle of approach)- Vessel, size, speed, engineering status- Time window to clear last vessel- Vessel Route (safe, heavy seas, etc...)

* Early decisions to leave port in an attempt to avoid hurricanes are crucial.*

11

6

2

3

4

5

7

8

21

1920

12

11

9

10

14

13

17

16

1815

1 - BOSTON 2 - NEWPORT 3 - NEW LONDON 4 - NEW YORK CITY 5 - PHILADELPHIA 6 - NORFOLK 7 - MOREHEAD CITY 8 - CHARLESTON 9 - SAVANNAH10 - KINGS BAY11 - MAYPORT12 - PORT EVERGLADES13 - KEY WEST14 - TAMPA15 - PENSACOLA16 - GULFPORT17 - NEW ORLEANS18 - PORT ARTHUR19 - GUANTANAMO BAY20 - ROOSEVELT ROADS21 - BERMUDA

Ports Evaluated in Hurricane Havens Handbook

for the North Atlantic (U.S. Navy)(U.S. Navy)

TROPICAL CYCLONE DISSIPATION

Recurvature:Tropical storm curves towards the NNE-E. Usually accelerating and decreasing in strength, often increasing in size. Speed is difficult to forecast.

Frictional forces of land: Often becoming extra-tropical as storm merges with frontal zone.

Unfavorable atmospheric/oceanographicinfluences:

Includes, but not limited to, upper level shearing, dry air intrusion in mid levels, cooler sea surface temperatures, upwelling behind other tropical systems, etc…

“Floyd”

“Charley”