A Practical Guide

to hurricane tracking and plotting

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Welcome to the practical guide to hurricane plotting and tracking, filled with tid-bits and other miscellaneous information. Here you may find the answer to a lot of your trivial (but oh so frustrating when you can't find the answer) questions. Somewhere else on our website we have information available on the current situation in the Caribbean. Our special local hurricane correspondents report from the Caribbean Islands about the situation with regards to threatening tropical systems. Reliable reports from the people who are in the middle of it all! For the latest advisories and satellite images see our Quick Hurricane Web Resource Locator, which will help you find the least overloaded web-server. Comments can be addressed to Gert van Dijken, site maintainer.

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A practical guide to hurricane tracking and plotting

Tracking and plotting the coordinates of the current position and its forecast of hurricanes is fun (as long as the eye stays away...)! But sometimes confusing! Those advisories from the National Hurricane Center use all those different units; knots, kilometers, miles, nautical miles, etc. Not sure about how many nautical miles are in a kilometer? Or how knots relate to miles per hour? And how can I calculate without too much work how far a storm is located from the Caribbean Islands.

When are they going to use your name for a Hurricane? Who came up with the titles of the National Hurricane Advisories; WTNT32.KNHC, MIASPFAT3, what do they mean? And then you've been looking at the strike probabilities of the storm, but the advisories are using those strange abbreviations, which island is TDPR or what's the code for St.Martin?

More questions. When is a tropical system a tropical storm and when becomes it a Category 3 hurricane? Will my mobile home survive this storm?

These facts are so trivial, but sometimes so hard to find. Very annoying when you are tracking and plotting Hurricane Edouard, Fran, Hortense or whoever. This page should give you the answers to these questions, and more...

Also, don't miss the feature about the Hurricane Hunters. These brave guys fly right into the eye of a hurricane to get the valuable data for hurricane forecasting! It is written by Martha Watkins Gilkes, and was published in the LIAT Islander Inflight Magazine.


Hurricane Names

Wondering when they are going to use your name for a tropical system? If they haven't used it in the last 6 years, the chance is pretty small that they ever will. This because hurricane names are recycled every 6 years. So the list of names for 1996 will be used again in 2002. However, often the names of some famous hurricanes have been dropped and replaced with something else. E.g. Luis has been replaced by Lorenzo and Andrew by Alex. It's likely that 1998 storms Georges and Mitch will become 'classics' as well. The names for the Atlantic are:

    2001        2002        2003        2004       2005       2006		              
1.  Allison     Arthur      Ana         Alex       Arlene     Alberto    
2.  Barry       Bertha      Bill        Bonnie     Bret       Beryl      
3.  Chantal     Cristobal   Claudette   Charley    Cindy      Chris      
4.  Dean        Dolly       Danny       Danielle   Dennis     Debby      
5.  Erin        Edouard     Erika       Earl       Emily      Ernesto    
6.  Felix       Fay         Fabian      Frances    Franklin   Florence
7.  Gabrielle   Gustav      Grace       Gaston     Gert       Gordon     
8.  Humberto    Hanna       Henri       Hermine    Harvey     Helene     
9.  Iris        Isidore     Isabel      Ivan       Irene      Isaac      
10. Jerry       Josephine   Juan        Jeanne     Jose       Joyce      
11. Karen       Kyle        Kate        Karl       Katrina    Kirk      
12. Lorenzo     Lili        Larry       Lisa       Lee        Leslie     
13. Michelle    Marco       Mindy       Matthew    Maria      Michael    
14. Noel        Nana        Nicholas    Nicole     Nate       Nadine     
15. Olga        Omar        Odette      Otto       Ophelia    Oscar      
16. Pablo       Paloma      Peter       Paula      Philippe   Patty
17. Rebekah     Rene        Rose        Richard    Rita       Rafael     
18. Sebastien   Sally       Sam         Shary      Stan       Sandy      
19. Tanya       Teddy       Teresa      Tomas      Tammy      Tony       
20. Van         Vicky       Victor      Virginie   Vince      Valerie    
21. Wendy       Wilfred     Wanda       Walter     Wilma      William    

How close is it? and How close can it get?

There is a storm brewing out there in the Atlantic, and you are wondering "How close is it?". Now you can accurately calculate the distance between the eye of the hurricane and your island. Just select your island and hurricane specifics like, the latitude and longitude coordinates of the storm and click on 'Show me how close...'. If your island is not listed you can enter your own coordinates.

In addition, you can enter the forward speed at which the hurricane is moving to calculate the time before the eye makes landfall at your location. If you know how far tropical storm winds extend from the center of the storm you can enter those as well to calculate how much preparation time you have left before winds will be blowing at tropical storm force. Caution: the numbers you get will only be true if the hurricane will travel in a straight line to your island at a constant speed and when you assume that the wind field doesn't change, in other words doesn't strengthen or weaken, over that time [this is normally not the case!!!].

Another tool available on this website calculates the closest point of approach of the eye of the storm to where you live from the 5-day forecast issued by the National Hurricane Center.

Select your Island:
Enter Hurricane Specifics:
The eye is located at:
It is moving near
TS winds extend from the center about
Or enter your Coordinates:
Lat: Lon:

Help? The latitude/longitude location of the center of the storm and the speed at which it is moving can be found in the Public Advisories. A 72 hour forecast of the wind radii are listed in the Marine Advisories. Often it might be better to take the 72 hour value for wind radius to account for changes in hurricane strength. Both products are issued by the National Hurricane Center and linked directly from the Quick Hurricane Web Resource Navigator (QHWRN). Note that the units in the Public Advisories are normally in miles and mph (miles per hour), and in the Marine Advisories in nm (nautical mile) and kt (nautical mile per hour). Lat/Lon should be entered in decimal degrees, not in the dd:mm:ss-format, so: 18.5, not: 18:30:00. Valid range: latitude 0-90 degrees, longitude: 0-180 degrees. When numbers are entered in the 'Or enter your Coordinates' box, the island selection is ignored. The coordinates for the islands are based on the corresponding National Weather Service weather stations. The algorithm and code for the distance calculation was provided by the National Geodetic Survey.


Unit Conversion

one kilometer (km):
0.62 mile
0.54 nautical mile
one mile (m):
1.61 kilometer
0.87 nautical mile
one nautical mile (nm):
1/60 degree latitude
1.85 kilometer
1.15 mile
one knot (kt):
one nautical mile per hour
1.85 km per hour
1.15 mile per hour (mph)

Use the following table for a quick estimate of travel time of a tropical system to the Leeward islands.

One degree longitude equals:
at latitudenautical milesmileskilometers
0° N60.069.2111.3
15° N58.166.8107.6
17.5° N57.366.0106.2
20° N56.565.0104.7

Example: Suppose that the center of a tropical storm is located at 15° N, 40° W, moving at 18 mph.
Most easterly Leeward islands located at around 61° W. This is a distance of 61-40=21° longitude. At 15° N this equals to 21x66.8= 1403 miles. So it will take around 1403/18= 78 hours or a 3 days and 6 hours to reach the islands. This is a rough estimate because the center of the storm has to stay on the same latitude and keep travelling at the same speed. You can also use the above form to calculate the distance and ETA.


The logic of NHC-advisories titles

WTNT32.KNHC, MIASPFAT3, etc., what do they mean? Which is which?

There are two different formats of NHC-advisories titles in use: (1) WTNT##.KNHC and (2) something like MIATCPAT#.

(1) WTNT##.KNHC: the first number (#) indicates the kind of advisory, the second the storm number. Marine Advisories have number 2, Public Advisories 3, Tropical Cyclone Discussions 4, Strike Probabilities 7. At times Tropical Cyclone Special Updates are released, numbered 6.

The storm numbers are as follows: Edouard has number 5, Fran 1 and Gustav 2.

Example: WTNT75.KNHC are the strike probablilites for Edouard.

(2) MIA*-format: Marine Advisories are titled MIATCMAT, Public Advisories MIATCPAT, Tropical Cyclone Discussions MIATCDAT, and the Strike Probabilities MIASPFAT. These are all followed by the number of the storm (see above).

Example: MIATCMAT2 (MIAmi Tropical Cyclone Marine Advisory Tropical Storm 2?) is the Marine Advisory for Gustav.


What time is it? Timezone confusion... UTC, AST, EDT?

Most advisories have the time in the local timezone of where the storm is, this can be AST, EDT,... Then on other advisories is just says something like 18:00 Z. That means 'Zulu' time, which is the same as Coordinated Universal Time (UTC), formerly known as Greenwich Mean Time (GMT). Below a quick reference table of some of the most common timezones used in the Caribbean and USA. Most islands are in the Atlantic Standard Timezone (AST) and do not observe daylight saving time (for a island-specific timezone list see: sizes.com).

Timezones relative to UTC (Current UTC Date/Time: Thu Apr 17 06:46:09 UTC 2014 ):

Daylight Saving Time:
     ADT (Atlantic Daylight Time): subtract 3 hours from UTC --> 03:46
     EDT (Eastern Daylight Time):  subtract 4 hours from UTC --> 02:46
     CDT (Central Daylight Time):  subtract 5 hours from UTC --> 01:46
     MDT (Mountain Daylight Time): subtract 6 hours from UTC --> 00:46
     PDT (Pacific Daylight Time):  subtract 7 hours from UTC --> 23:46
 
Standard Time:
     AST (Atlantic Standard Time): subtract 4 hours from UTC --> 02:46
     EST (Eastern Standard Time):  subtract 5 hours from UTC --> 01:46
     CST (Central Standard Time):  subtract 6 hours from UTC --> 00:46
     MST (Mountain Standard Time): subtract 7 hours from UTC --> 23:46
     PST (Pacific Standard Time):  subtract 8 hours from UTC --> 22:46


How to read Marine Advisories and Reconnaisance Reports

The Marine Advisories give information about the current and forecasted windfield and sea conditions around the center of the storm. Important to check is that if a Hurricane does not make landfall to see how close it passes by.

An example of a small piece taken out of the Marine Advisory of Hortense of 11PM/Sep 11:

     EYE DIAMETER  16 NM
     MAX SUSTAINED WINDS  85 KT WITH GUSTS TO 105 KT
     64 KT....... 50NE  25SE  25SW  25NW
     50 KT.......100NE  50SE  30SW  60NW
     34 KT.......175NE 150SE  50SW 120NW
     12 FT SEAS..175NE 150SE  50SW 120NW
     ALL QUADRANT RADII IN NAUTICAL MILES

All numbers are in nautical miles (nm). One nm equals 1.15 mile. In the above example the diameter of the eye is 16 nm (18 miles). Maximum sustained winds near the center are 85 kts (98mph) with gusts to 121 mph (105kt). Now comes the interesting part. Up to 50 nm to the North East of the center 64 kt winds (hurricane force) occur, and up to 25 nm to the SE, SW and NW. Connecting those points will make a kind of 'crooked' circle around the center. The same goes for the 50 kt, 34 kt (tropical storm) and 12 ft seas. So you can see from these data that the storm is a-symmetrical and that the 'grunt' of the storm is on the North-Eastern side.

At the time of this advisory Turks Island was 35 miles (30 nm) to the West of the center, so they are just outside the range of (sustained) hurricane force winds. If they would have been to the North West of the center they would be in the range of 64 kt winds. Since there are gusts to 105 kt (121 mph) they will experience hurricane force winds from time to time.

From time to time the National Hurricane Center sends out reconnaisance airplanes to the eye of the storm. If you are a serious 'hurricane tracker' you must check out those Reconnaisance Reports. This document tells you exactly how to decode it. It was written by Chris Sells and forwarded to me by Chris Novy.


Abbreviations in Strike Probabilities (and current weather conditions)

Weather Station Identifiers for most of the Caribbean Islands as reported in the NHC Strike Probabilities Advisories. A complete list of all weather stations around the world can be found on the National Weather Service website. You can also click on the station identifier to get the current weather conditions (if available) from the Internet Weather Source (NWS).

station
identifier
station island latitude longitude elevation
(meters)
TRPM Blackburne / Plymouth Antigua and Barbuda 16-45N 062-10W 12
TKPN Charlestown / Newcast Antigua and Barbuda 17-12N 062-35W 17
TAPA Vc Bird International Airport Antigua and Barbuda 17-07N 061-47W 8
TNCA Queen Beatrix Airport Aruba 12-30N 070-01W 18
MYBS Alice Town, Bimini Bahamas 25-44N 079-18W 2
MYSM Cockburn Town, San Salvador Bahamas 24-03N 074-32W 3
MYGF Freeport, Grand Bahama Bahamas 26-33N 078-42W 2
MYEG George Town, Exuma Bahamas 23-30N 075-46W 2
MYIG Matthew Town, Inagua Bahamas 20-57N 073-41W 2
MYNN Nassau Airport Bahamas 25-03N 077-28W 3
MYGW West End, Grand Bahama Bahamas 26-42N 078-58W 2
TBPO Bridgetown City Barbados 13-06N 059-37W 50
TBPB Grantley Adams Barbados 13-04N 059-29W 50
TNCB Flamingo Airport Bonaire, N.A. 12-09N 068-17W 6
MWCR Owen Roberts Airport, Grand Cayman Cayman Islands 19-17N 081-21W 3
MUHA Aeropuerto Jose Mar-Ti, Rancho-Boyeros, Habana Cuba 22-59N 082-24W 59
MUBA Baracoa, Oriente Cuba 20-21N 074-30W 9
MUBY Bayamo Cuba 20-24N 076-37W 64
MUCM Camaguey Aeropuerto Cuba 21-25N 077-51W 122
MUCL Cayo Largo Del Sur Cuba 21-37N 081-33W 2
MUCF Cienfuegos, Las Villas Cuba 22-09N 080-24W 39
MUGM Guantanamo, Oriente Cuba 19-54N 075-08W 23
MUGT Guantanamo, Oriente Cuba 20-05N 075-09W 8
MUHG Holguin Civ / Mil Cuba 20-47N 076-19W 106
MUVT Las Tunas, Las Tunas Cuba 20-57N 076-57W 106
MUMZ Manzanillo, Oriente Cuba 20-20N 077-07W 60
MUMO Moa Military Cuba 20-39N 074-55W 5
MUNG Nueva Gerona, Isla De Pinos Cuba 21-50N 082-47W 23
MUPR Pinar Del Rio, Pinar Del Rio Cuba 22-25N 083-41W 37
MUCU Santiago De Cuba, Oriente Cuba 19-58N 075-51W 69
MUVR Varadero, Matanzas Cuba 23-08N 081-17W 3
MUCA Venezuela, Ciego De Avila Cuba 21-47N 078-47W 26
TNCC Hato Airport Curacao, N.A. 12-12N 068-58W 9
TDCF Canefield Airport Dominica 15-32N 061-24W 5
TDPD Melville Hall Airport Dominica 15-32N 061-18W 13
TDPR Roseau Dominica 15-18N 061-24W 72
MDBH Barahona Dominican Republic 18-12N 071-06W 3
MDLR La Romana International Airport Dominican Republic 18-25N 068-57W 8
MDSD Las Americas Dominican Republic 18-26N 069-40W 18
MDPP Puerto Plata International Dominican Republic 19-45N 070-33W 15
MDPC Punta Cana Dominican Republic 18-34N 068-22W 12
MDSI San Isidro Air Force Base Dominican Republic 18-30N 069-46W 111
MDST Santiago Dominican Republic 19-27N 070-42W 183
TGPY Point Salines Airport Grenada 12-00N 061-47W 6
TFFR Le Raizet Guadeloupe 16-16N 061-31W 11
MTCH Cap-Haitien Haiti 19-45N 072-11W 2
MTPP Port-Au-Prince / Aeroport International Haiti 18-34N 072-18W 31
MKJP Kingston / Norman Manley Jamaica 17-56N 076-47W 3
MKJS Montego Bay / Sangster Jamaica 18-30N 077-55W 1
TFFF Le Lamentin Martinique 14-36N 061-00W 5
TJBQ Aquadilla / Borinquen Puerto Rico 18-30N 067-08W 72
TJSJ Luis Munoz Marin Puerto Rico 18-27N 066-00W 3
TJMZ Mayaguez / Eugenio Puerto Rico 18-16N 067-09W 9
TJPS Ponce / Mercedita Puerto Rico 18-01N 066-34W 9
TJNR Roosevelt Roads, Naval Station Puerto Rico 18-15-19N 065-38-19W 11
TFFJ Gustavia Saint Barthelemy 17-54N 062-51W 48
TISX Christiansted / Alex. Hamilton Field Saint Croix 17-42N 064-48W 17
TNCE Roosevelt Airport Saint Eustatius, N.A. 17-29N 062-59W 38
TKPK Golden Rock Saint Kitts and Nevis 17-18N 062-41W 48
TLPL Hewanorra International Airport Saint Lucia 13-45N 060-57W 3
TLPC Vigie Saint Lucia 14-01N 061-00W 2
TNCM Juliana Airport Saint Maarten, N.A. 18-03N 063-07W 4
TIST Charlotte Amalie, Cyril E. King International Airport Saint Thomas, U.S.V.I. 18-20N 064-59W 7
TVSV Arnos Vale Saint Vincent and the Grenadines 13-08N 061-12W 9
TTPT Crown Point Airport Tobago 11-09N 060-50W 3
TTCP Crown Pt./ Scarborou Tobago 11-09N 060-51W 8
TUPJ Beef Island Tortola, B.V.I. 18-27N 064-32W 4
TTPP Piarco International Airport Trinidad 10-37N 061-21W 12

Tropical Systems

Tropical disturbance, tropical wave:
Unorganized mass of thunderstorms, very little, if any, organized wind circulation.
Tropical depression:
Evidence of closed wind circulation around a center with sustained winds from 20-34 knots (23-39 mph).
Tropical storm:
Maximum sustained winds are from 35-64 knots (40-74 mph). The storm is named once it reaches tropical storm strength.
Hurricane:
Maximum sustained winds exceed 64 knots (74 mph).

Saffir Simpson Hurricane Intensity Scale

Category One - A Minimal Hurricane
Winds: 74-95 mph, 64-83 kts, 119-153 km/h
Minimum surface pressure: higher than 980 mbar
Storm surge: 3-5 ft, 1.0-1.7 m
Damage primarily to shrubbery, trees, foliage, and unanchored homes. No real damage to other structures. Some damage to poorly constructed signs. Low-lying coastal roads inundated, minor pier damage, some small craft in exposed anchorage torn from moorings. Example: Hurricane Jerry (1989)
Category Two - A Moderate Hurricane
Winds: 96-110 mph, 84-96 kts, 154-177 km/h
Minimum surface pressure: 979-965 mbar
Storm surge: 6-8 ft, 1.8-2.6 m
Considerable damage to shrubbery and tree foliage; some trees blown down. Major damage to exposed mobile homes. Extensive damage to poorly constructed signs. Some damage to roofing materials of buildings; some window and door damage. No major damage to buildings. Coast roads and low-lying escape routes inland cut by rising water 2 to 4 hours before arrival of hurricane center. Considerable damage to piers. Marinas flooded. Small craft in unprotected anchorages torn from moorings. Evacuation of some shoreline residences and low-lying areas required. Example: Hurricane Bob (1991)
Category Three - An Extensive Hurricane
Winds: 111-130 mph, 97-113 kts, 178-209 km/h
Minimum surface pressure: 964-945 mbar
Storm surge: 9-12 ft, 2.7-3.8 m
Foliage torn from trees; large trees blown down. Practically all poorly constructed signs blown down. Some damage to roofing materials of buildings; some wind and door damage. Some structural damage to small buildings. Mobile homes destroyed. Serious flooding at coast and many smaller structures near coast destroyed; larger structures near coast damaged by battering waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Flat terrain 5 feet of less above sea level flooded inland 8 miles or more. Evacuation of lowlying residences within several blocks of shoreline possibly required. Example: Hurricane Gloria (1985)
Category Four - An Extreme Hurricane
Winds 131-155 mph, 114-135 kts, 210-249 km/h
Minimum surface pressure: 944-920 mbar
Storm surge: 13-18 ft, 3.9-5.6 m
Shrubs and trees blown down; all signs down. Extensive damage to roofing materials, windows and doors. Complete failures of roofs on many small residences. Complete destruction of mobile homes. Flat terrain 10 feet of less above sea level flooded inland as far as 6 miles. Major damage to lower floors of structures near shore due to flooding and battering by waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Major erosion of beaches. Massive evacuation of all residences within 500 yards of shore possibly required, and of singlestory residences within 2 miles of shore. Example: Hurricane Andrew (1992)
Category Five - A Catastrophic Hurricane
Winds: greater than 155 mph, 135 kts, 249 km/h
Minimum surface pressure: lower than 920 mbar
Storm surge: higher than 18 ft, 5.6 m
Shrubs and trees blown down; considerable damage to roofs of buildings; all signs down. Very severe and extensive damage to windows and doors. Complete failure of roofs on many residences and industrial buildings. Extensive shattering of glass in windows and doors. Some complete building failures. Small buildings overturned or blown away. Complete destruction of mobile homes. Major damage to lower floors of all structures less than 15 feet above sea level within 500 yards of shore. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Massive evacuation of residential areas on low ground within 5 to 10 miles of shore possibly required. Example: Hurricane Camille (1969)

In case of emergency: the Amateur Radio Operators are standing by

When everything else fails... When one of the Caribbean Islands is under threat of a tropical system I publish eye-witness reports from our Special Hurricane Correspondents on the Caribbean Hurricane Network. These reports come in by e-mail. If there is a big hit, it will be very likely that power and phonelines will be down, so the chance will be quite small of getting those reports by e-mail (no power=no pc; no phone=no dial-up with modem to isp). This of course doesn't only affect me but all emergency workers. This works the other way as well, when power and phones are down, people in the affected areas have a hard time of getting timely information. This is the time when the Amateur Radio Operators come in. Radio waves will always travel when you have a generator or other kind of power backup. Irvine B. Niffikeer, one of my hurricane correspondents on Trinidad & Tobago, forwarded me the following information on how to catch the emergency reports:

In the event of a disaster -God forbid-, one can obtain information from Amateur Radio Operators in the West Indies on the following frequencies:

Because of modern technology e.g. satellite pictures, one can tell in advance when a hurricane is likely to strike. In this situation, amateur radio operators will secure antennas and may shut down their stations about 1 hour before the hurricane strikes. During this period there will be lightning and strong winds until the hurricane passes. This period can be 2 to 3 hours.

Only those stations that took the necessary precaution and preparation in time will be heard on the air.

I hope you find this information useful and informative so that people can be aware of what is likely to happen in the event of a National Disaster and will be more enlightened and cooperate when the real situation occurs -God forbid-.

Irvine B. Niffikeer -9Y4IBN-.
i9y4ibn@carib-link.net
http://www.angelfire.com/nf/9y4ibn/


Hurricane Website Links

National Hurricane Center Advisories are released at 03:00, 09:00, 15:00 and 21:00 GMT. Intermediate advisories are released at 00:00, 06:00, 12:00 and 18:00 GMT. GMT is 4 hours ahead of Eastern Daylight Time.

It is now: Thursday, 17-Apr-2014 06:46:09 GMT


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