tropical revolving strom

7/28/2019 tropical revolving strom

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* These are just of few of the references available

covering Tropical Cyclones, their effects on theMarine Industry and Marine Safety. *

Mariners Guide for Hurricane Awareness in the North AtlanticBasin (NOAA)

American Practical Navigator (Bowditch)

Port Heavy Weather Guide

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

REFERENCES


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TROPICAL CYCLONEDEFINED!

A warm core, non-frontal,synoptic scale system withcyclonically rotating windscharacterized by a rapiddecrease in pressure andincrease in winds toward thecenter of the storm.Cyclones develop over

tropical or subtropicalwaters and have a definiteorganized circulation.


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How do they develop?

Favorable environmental conditions that must be

in place before a tropical cyclone can form:

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

An atmosphere which cools fast with height (potentiallyunstable).

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 andthe upper troposphere. (Vertical wind shear is the changein wind speed with height.)

Outflow aloft/exhaust


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STAGES OF

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

Tropical Storm (TS): A tropical cyclone with wind speeds 34 to 63knots. Identified by names in alphabetical order consistent with formationdate/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.


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TROPICAL DEPRESSION(Formative Stage)

Winds < 34 kts

Tropical wave develops a

weak cyclonic circulation

Identified by thickening

clusters of thunderstorms

on satellite

Central pressure falls

rapidly below 1002mb if

system intensifies


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TROPICAL STORM(Immature to Mature Stage)

Winds 34 - 63 kts

Closed formation expands with spiralbands becoming better organized

Increasing sea state makes navigation

near the center increasinglydifficult and dangerous


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HURRICANE / TYPHOON / WILLY-WILLY(Mature Stage)

Winds > 63 kts

DANGEROUSLY HIGH

SEAS navigation severely impaired

Radius of strong winds may exceed 350NM

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


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TROPICAL CYCLONEStages of Development

1. Tropical Easterly Wave 3. Tropical Storm

2. Tropical Depression 4. Hurricane


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Most damagingaspects of a hurricane:

AT SEA:

HIGH SEAS

HIGH WINDS

INPORT:

STORM SURGE

TORNADO/SVR TSTMSHIGH WINDS


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HURRICANE CATEGORIES

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

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

Category 3 (Extensive) - Winds 96 to 112 knots, storm surge 9 to 12 ft abovenormal. Major damage to structures, poorly constructed building destroyed.Serious flooding along the coast, extensive flooding may extend inland 8miles. Examples: Keith 2000, Fran 1996, Opal 1995, Alicia 1983 and Betsy1965

Saffir- Simpson Scale


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HURRICANE CATEGORIEScont.

Category 4 (Extreme)

Winds 113 to 136 knots, storm

surge 13 to 18 ft above normal.

Extensive roofing and window

damage, complete destruction ofmobile homes. Areas above 10 ft

flooded inland up to 6 miles, major

erosion of beaches, massive

evacuation of coastal areas.

(ANDREW 1992)


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Category 5 (Catastrophic)

Winds above 137 knots, storm

surge greater than 18ft above

normal. Complete failure of roof

structures and very severe windowand door damage, some complete

buildings fail. Major damage to

structures lower than 15 ft above

sea level, massive evacuations of

residential units within 10 miles ofthe coast.

(CAMILLE 1969)

AUG 16, 1969

HURRICANE CATEGORIES

cont.


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Richelieu Apartments

The Power of a Category 5 Hurricane Camille

The Mansion

BEFORE!AFTER!


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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 oftropical storms, and hurricanes, created in each basin.

TROPICAL CYCLONE

FORMATION,LOCATION


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Hurricane Season Atlantic

01 June - 30 November

Eastern Pacific

15 May - 30 November

Western Pacific

Year round

TROPICAL CYCLONEFORMATION CONT.

2005 ATLANTICTROPICAL CYCLONENAMES

LeeMaria

NateOpheliaPhilippeRitaStan

TammyVinceWilma

ArleneBret

CindyDennisEmilyFranklinGert

HarveyIreneJoseKatrina


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TROPICAL CYCLONECHARACTERISTICS

Feeder Bands (curvedlines of convection)spiral inward to the EyeWall. Some of the mostviolent weather(tornadoes/severethunderstorms) occur inthese areas

Pumping Actionannounces the

approach of, andpassing of the TropicalCyclone


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Clouds

Most significant clouds areheavy Cumulus andCumulonimbus

Spiral bands of CU/CB

inward toward outer edge ofeye

Cirrus changing toCirrostratus and lowering,

good indicator of approachingTC for the mariner

Cloud sequence similar to

approaching warm front

TROPICAL CYCLONE

CHARACTERISTICS, CLOUDS


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18AUG 15Z 19AUG 12Z 20AUG 12Z

970

975

990

985

980

995

1005

1000

1020

1015

1010

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

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 TRACE

Hurricane Bob 1991 Newport, RI

TROPICAL CYCLONECHARACTERISTICS, ISOBARS/PRESSURE


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Time (UTC) Task / Event

00:00Synoptic time, cycle begins, receive

aircraft fix (generally within +/- 00:30)

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

01:00 Initialize models

01:20 Receive model guidance, begin preparingforecast

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


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Hurricane Isabel Track Guidance

1800 UTC 10 Sep 2003


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0

100

200

300

400

500

600

700

1954

1957

1960

1963

1966

1969

1972

1975

1978

1981

1984

1987

1990

1993

1996

1999

2002

year

errorinn.mi

Tropical Prediction Center Performance Measuresyearly-average official track forecast errors and trend lines, Atlantic basin

120-hour

96-hour

72-hour

48-hour 24-hour

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


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UNDERWAY 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!


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MONITOR THE STORM

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

NAVTEX

SafetyNet

Annotated on weather facsimile charts

Private weather routing companies

E-mail List servers from the National Hurricane Center


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1-2-3 Rule


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WARNINGS

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


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WARNINGS, 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

24 HR FORECAST POSITION CURRENT POSITION

DANGER

AREA


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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

200 NM

200 NM

300 NM

300 NMDANGERAREA

DANGER

AREA

DANGERAREA

WARNINGS, cont.


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Meteorological elements are

not uniformly distributedthroughout a tropical

Storm is divided intoleft/right semicircles and

quadrants, relative to the

direction of motion

Usually strongest winds are

on right side in N.H. (added

to motion)

TROPICAL CYCLONE

EVASION


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TROPICAL CYCLONE

EVASION cont.

Storms location relative

to own ships position:

Dangerous semi-circle:Wind greater due to wind

augmented by the forward

motion of the storm.

Less Dangerous semi-circle:

Wind decreased by forwardmotion of the storm.

Winds and seas forcevessel into path of storm.

Winds blow vessel awayfrom storm track.


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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


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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


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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.


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

300 NM +

TROPICAL CYCLONE

EVASION cont.


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Never cross the T: Do not plan to cross the track of ahurricane.

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 youare at least 300NM from the center.

Follow the 1 2 3 Rule

TROPICAL CYCLONE

EVASION cont.


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Monitor warnings and advisories to prevent an encounter.

Forecast Track Tendencies: Comparison of the most recent NHC forecast track withforecast 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 foravoidance, particularly in the 2-3 day forecast range & beyond.

TROPICAL CYCLONE

EVASION cont.


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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 the

open waters of the North Atlantic, but becomes extremely important in the

confined waters of the Western Caribbean Sea/Gulf of Mexico.

More often than not, early decisions to leave restricted maneuver areas

are the most sensible choice.

TROPICAL CYCLONE

EVASION cont.


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IN PORT


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MONITORING THE STORM

NHC Warnings/Bulletins

Local Radio / TV stations

Port Authority / Coast Guard

Internet


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CONDITIONS OF READINESSCONDITION 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 areanticipatedwithin 24 hours.

Yankee

CONDITION 1 - Destructive force winds areanticipatedwithin 12 hours.

Zulu

These are the most common conditions of readiness.

St I t


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Stay Inport

orRide it out at Sea?

Factors to consider!The decision to leave port for hurricane avoidance must be made veryearly, 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.*

Ports Evaluated in Hurricane Havens Handbook


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11

6

2

3

4

5

7

8

21

19

20

12

119

10

14

13

17

16

1815

1 - BOSTON2 - NEWPORT

3 - NEW LONDON

4 - NEW YORK CITY

5 - PHILADELPHIA

6 - NORFOLK

7 - MOREHEAD CITY

8 - CHARLESTON

9 - SAVANNAH

10 - KINGS BAY

11 - MAYPORT

12 - PORT EVERGLADES13 - KEY WEST

14 - TAMPA

15 - PENSACOLA

16 - GULFPORT

17 - NEW ORLEANS

18 - PORT ARTHUR19 - GUANTANAMO BAY

20 - ROOSEVELT ROADS

21 - BERMUDA

for the North Atlantic (U.S. Navy)


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TROPICAL CYCLONEDISSIPATION

Recurvature:Tropical storm curves towards the NNE-E.

Usually accelerating and decreasing instrength, often increasing in size. Speed isdifficult to forecast.

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

Unfavorable atmospheric/oceanographicinfluences:

Includes, but not limited to, upper levelshearing, dry air intrusion in mid levels,cooler sea surface temperatures, upwelling

behind other tropical systems, etc

Floyd

Charley


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