2REFERENCES* 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 GuideHurricane Havens Handbook for the North Atlantic (U.S. Navy)
3TROPICAL CYCLONE 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.
4How 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 thetroposphere (16,000 ft / 4,900 m).Generally a minimum distance of at least 300miles (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 change in wind speed with height.)Outflow aloft/exhaust
5STAGES OF DEVELOPMENTTropical 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.
6TROPICAL (EASTERLY) WAVE No significant winds or seasNo defined near surfacecirculationIdentified by areas ofConvergence (thunderstorms)
8TROPICAL STORM (Immature to Mature Stage) Winds ktsClosed formation expands with spiralbands becoming better organizedIncreasing sea state makes navigation near the center increasinglydifficult and dangerous
9HURRICANE / TYPHOON / WILLY-WILLY (Mature Stage) Winds > 63 ktsDANGEROUSLY HIGHSEAS navigation severely impairedRadius of strong winds may exceed 350 NMGale Force Winds extend out further in right front quadrant (typically 120 NM)
10TROPICAL CYCLONE Stages of Development 1. Tropical Easterly Wave 3. Tropical Storm2. Tropical Depression Hurricane
11Most damaging aspects of a hurricane: INPORT:STORM SURGETORNADO/SVR TSTMSHIGH WINDSAT SEA:HIGH SEASHIGH WINDS
12HURRICANE CATEGORIES Saffir- Simpson Scale 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 1995Category 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 1985Category 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
13HURRICANE CATEGORIES cont. 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)
15HURRICANE CATEGORIES cont. Category 5 (Catastrophic)Winds above 135 knots, stormsurge greater than 18ft abovenormal. 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
16The Power of a Category 5 “Hurricane Camille” BEFORE!AFTER!Richelieu ApartmentsThe Mansion
17TROPICAL CYCLONE FORMATION, LOCATION 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.
182005 ATLANTIC TROPICAL CYCLONE NAMES FORMATION CONT.2005 ATLANTIC TROPICAL CYCLONE NAMESHurricane Season Atlantic01 June NovemberEastern Pacific15 May NovemberWestern PacificYear roundArleneBretCindyDennisEmilyFranklinGertHarveyIreneJoseKatrinaLeeMariaNateOpheliaPhilippeRitaStanTammyVinceWilma
20Distribution of Surface Winds 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 nm from the center of the storm.Hurricane Andrew Strong CAT 4
21TROPICAL CYCLONE CHARACTERISTICS 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 Cyclone23263935
22TROPICAL CYCLONE CHARACTERISTICS, CLOUDS Most significant clouds are heavy Cumulus and CumulonimbusSpiral bands of CU/CB inward toward outer edge of eyeCirrus changing to Cirrostratus and lowering, good indicator of approaching TC for the marinerCloud sequence similar to approaching warm front
23BAROGRAPH TRACE Hurricane Bob 1991 Newport, RI TROPICAL CYCLONE CHARACTERISTICS, ISOBARS/PRESSURE18AUG 15Z19AUG 12Z20AUG 12Z9709759909859809951005100010201015101018Z15Z21Z00Z03Z06Z09ZMILLIBARSBAROGRAPH TRACE Hurricane Bob 1991 Newport, RIIsobars nearly symmetrical or elliptical in shapeTightest isobaric gradient to right of storms line of movementCentral pressures well below average (890 – 940 mb not uncommon)Barograph trace often shows “V” as eye passes (not something a ship wishes to see).24274036
24TPC/NHC Six-hour forecast cycle Time (UTC)Task / Event00:00Synoptic time, cycle begins, receive aircraft fix (generally within +/- 00:30)00:45Receive satellite fix data (TAFB, SAB, AFWA)01:00Initialize models01:20Receive model guidance, begin preparing forecast02:00NWS/DOD hotline coordination call (international coordination, if necessary)03:00Advisory package deadline03:15FEMA conference call06:00Next cycle begins
25Hurricane Isabel Track Guidance 1800 UTC 10 Sep 2003
28BIG IMPROVEMENTS IN TC TRACK FORECASTS OVER RECENT DECADE, ESPECIALLY BEYOND 2 DAYS
29UNDERWAYA 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!
30MONITOR THE STORMNational Hurricane Center issues warnings every 6 hours 0300Z, 0900Z, 1500Z, 2100ZNAVTEXSafetyNetAnnotated on weather facsimile chartsPrivate weather routing companiesList servers from the National Hurricane Center
32WARNING’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.100 NM135 NM24 HR FORECAST POSITIONCURRENT POSITION
33WARNING’S, cont. DANGER AREA 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 AREATANGENT100 NMDANGER AREA100 NMTANGENT24 HR FORECAST POSITIONCURRENT POSITION
34WARNING’S, cont.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.300 NM200 NMDANGER AREA100 NMDANGER AREA300 NM200 NMDANGER AREA100 NM72 Hr48 Hr24 HrCurrent43465762
35TROPICAL CYCLONE EVASION Meteorological elements are not uniformly distributed throughout a tropicalStorm is divided into left/right semicircles and quadrants, relative to the direction of motionUsually strongest winds are on right side in N.H. (added to motion)
36TROPICAL CYCLONE EVASION cont. Storm’s location relativeto own ship’s position:Dangerous semi-circle:Wind greater due to windaugmented by the forwardmotion of the storm.“Less Dangerous” semi-circle:Wind decreased by forwardWinds and seas forcevessel into path of storm.Winds blow vessel awayfrom storm track.
37TROPICAL 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
38TROPICAL 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
39TROPICAL CYCLONE EVASION cont. 157 DEG RELBEHIND CENTER (ON STORM TRACK)Avoid center by best practical course (storm may recurve).AHEAD OF CENTER (ON STORM TRACK)Maneuver ship so that relative wind is 157 degrees relative, hold course and speed.
40TROPICAL 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 +
41TROPICAL 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
42TROPICAL 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.
43TROPICAL CYCLONE EVASION cont. Assess your options: Plan Ahead. Never leave yourself with only asingle 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.
46MONITORING THE STORM Local Radio / TV stations NHC Warnings/BulletinsLocal Radio / TV stationsPort Authority / Coast GuardInternet
47CONDITIONS OF READINESS CONDITION 5 - Destructive force winds (35 kts or as specified ) are possiblewithin 96 hours.CONDITION 4 - Destructive force winds are possible within 72 hours.WhiskeyCONDITION 3 - Destructive force winds are possible within 48 hours.X-RayCONDITION 2 - Destructive force winds are anticipated within 24 hours.YankeeCONDITION 1 - Destructive force winds are anticipated within 12 hours.ZuluThese are the most common conditions of readiness.
48Stay Inport or Ride it out at Sea? 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.*
49Ports Evaluated in Hurricane Havens Handbook for the North Atlantic (U Ports Evaluated in Hurricane Havens Handbook for the North Atlantic (U.S. Navy)1 - BOSTON2 - NEWPORT3 - NEW LONDON4 - NEW YORK CITY5 - PHILADELPHIA6 - NORFOLK7 - MOREHEAD CITY8 - CHARLESTON9 - SAVANNAH10 - KINGS BAY11 - MAYPORT12 - PORT EVERGLADES13 - KEY WEST14 - TAMPA15 - PENSACOLA16 - GULFPORT17 - NEW ORLEANS18 - PORT ARTHUR19 - GUANTANAMO BAY20 - ROOSEVELT ROADS21 - BERMUDA1412163851067921111214181517131920
50TROPICAL 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”