12 December 2003

2003 Tropical Atlantic Activity Summary


The hurricane season is over, so it is time for my annual Season Summary. I sent out about 65 updates to this mailing list (which has grown from about 4 subscribers in 1996 to 240 subscribers in 2003, not to mention the updates being posted on several websites) over the past 9 months; now it's time for the final one. This report is structured in the following manner: 1) the Saffir-Simpson Scale, 2) Lifetimes and Intensities, 3) Climatology and Statistics, and 4) Landfall.
As usual, my data (which in large part comes from The National Hurricane Center and Unisys Weather) and typing could contain errors, so if you see a mistake, please point it out to me.

1. Saffir-Simpson Scale of Tropical Cyclone Intensity

CATEGORY            WINDS (mph)   PRESSURE (millibars)
------------------- ----------    ------------------
depression          23- 39        N/A
tropical storm      40- 73        N/A
1                   74- 95        > 980
2                   96-110        965-979
3                  111-130        945-964
4                  131-155        920-944
5                     >156        < 919

2. Lifetimes and Intensities
----------------------------------------------------
NAME       DATES OF          MAX WIND    MIN PRES
         ACTIVITY         (kts)        (mb)
---------- ---------------- ------------ -------------
ANA        21 APR - 24 APR        45        996 (N)
TD2        11 JUN - 12 JUN        30       1008
BILL       29 JUN - 01 JUL        50        997 (N)
CLAUDETTE  08 JUL - 16 JUL        70        981 (N,H)
DANNY      16 JUL - 20 JUL        65       1005 (N,H)
TD6        19 JUL - 21 JUL        30       1008
TD7        25 JUL - 26 JUL        30       1016
ERIKA      14 AUG - 17 AUG        65        986 (N,H)
TD9        21 AUG - 22 AUG        30       1008
FABIAN     27 AUG - 08 SEP       125        939 (N,H,M)
GRACE      30 AUG - 31 AUG        35       1007 (N)
HENRI      03 SEP - 08 SEP        45        997 (N)
ISABEL     06 SEP - 19 SEP       140        920 (N,H,M)
TD14       08 SEP - 10 SEP        30       1007
JUAN       25 SEP - 29 SEP        90        970 (N,H)
KATE       25 SEP - 07 OCT       110        952 (N,H,M)
LARRY      02 OCT - 06 OCT        50        993 (N)
MINDY      10 OCT - 14 OCT        40       1002 (N)
NICHOLAS   13 OCT - 23 OCT        60        990 (N)
ODETTE     04 DEC - 07 DEC        55        993 (N)
PETER      09 DEC - 11 DEC        60        990 (N)

In the previous chart, the N, H, and M that follows some storms denote what statistic they contributed to; Named storm (TS+), Hurricane (CAT1+), Major hurricane (CAT3+).
The winds and pressures reflect the data as posted in the operational advisories, NOT the final “best-track” data that will be available from the NHC in the post-season timeframe.

3. Climatology and Statistics
----------------------------------------------------
The average annual number of tropical disturbances (for the period 1950-2000) is:
9.6 named storms
5.9 hurricanes
2.3 major hurricanes

This year, the numbers were near the average:
16 named storms (12 in 2002)
7 hurricanes (4 in 2002)
3 major hurricanes (2 in 2002)

A fairly unique aspect of the past season was the early start and late end to the activity. Ana formed in late April, nearly six weeks before the official beginning of hurricane season. Then two storms formed in June and four in July; also unusually active so early in the season. For the second consecutive year, no storms formed during November. Then Odette and Peter both formed in December, after the official end of hurricane season.

Although there were 16 named storms, which is already above average, there were also 5 Tropical Depressions that never got named. TD2, TD6, TD7, TD9, and TD14 were scattered across the basin and across the season. Perhaps of most interest was TD14 which formed out at 22°W, east of the Cape Verde Islands; this is remarkable because it’s only 500km off the African coast. If large-scale conditions had been just a bit more favorable, it’s possible that all of these unnamed Depressions would have made it to Tropical Storm strength and 2003 would have been a close match for the amazing 1933 season (21 named storms and 10 hurricanes).

Curiously, the Caribbean Sea was completely devoid of any hurricane activity all season. Only TD9, Claudette, and Odette passed through the Caribbean, and they were all below hurricane strength. The Gulf of Mexico was also nearly devoid of hurricane activity, but Claudette and Erika both became hurricanes briefly on the western periphery of the Gulf. This is in stark contrast to 2002 where the Caribbean was home to two major hurricanes and the central Gulf was crowded with overlapping storm tracks.

For the first time since October 1998 (Mitch), a Category 5 hurricane occurred in the Atlantic. Hurricane Isabel was not only a CAT5 storm, but maintained that intensity for a total of 192 hours while passing well north of the Lesser Antilles!

The three intense hurricanes (Fabian, Isabel, and Kate) were also notable because they maintained that intensity for so long. Fabian contributed 6.5 Intense Hurricane Days, Isabel contributed 8.0, and Kate contributed 1.5. Kate was rather typical, but Fabian and Isabel were among the longest-lived intense hurricanes to ever stir up the Atlantic basin. This is the only time that two intense hurricanes each surpassed 6 “intense hurricane days” since 1900.

There were a total of 75.75 “named storm days” (days during which a storm with 35kt+ winds was present). 31.75 of those days were "hurricane days", and 16.25 of those days were "intense hurricane days". This is 171% of the climatological mean, i.e., this season was over 2/3 more active than the "normal" season. The average numbers (for the period 1950-2000) are 49.1 named storm days, 24.5 hurricane days, and 5.0 intense hurricane days. You can compare this season and recent past seasons at

Here is a summary of the season (VERY brief):

Ana formed in late April near Bermuda from a subtropical Low. The Low gradually acquired tropical characteristics as it tracked eastward with a mid-latitude disturbance. This was the first April tropical cyclone in the Atlantic ever.

Bill also did not begin as a tropical wave, but developed in the southern Gulf of Mexico. It tracked northward into the central Louisiana coast, causing coastal flooding and several tornadoes.

The third storm of the season was the first to have purely tropical origins. Claudette formed south of Hispaniola and tracked westward across the Caribbean Sea, nipping the northeast tip of the Yucat√°n Peninsula, then continuing northwest across the Gulf. The storm briefly intensified to a hurricane just prior to making landfall north of Corpus Christi, TX. The winds were slow to spin down after landfall, and maintained TS strength for over a day, dumping 5” of rain on parts of Texas.

Danny formed from a tropical wave, but the first advisory was only written when the storm was at 31°N. It completed an arc over the north central Atlantic, never affecting anything.

Erika would be the last of the storms with non-tropical origins… forming from a surface Low along a cold front just northwest of Key West, FL. It tracked westward and briefly reached hurricane strength before making landfall in northeast Mexico.

Fabian formed out at 31°W and became the first major hurricane of the season at about 50°W. The storm followed a track around the periphery of the subtropical High. This included the eyewall passing directly over Bermuda as a Category 3 hurricane, causing tremendous damage to the tiny island.

Grace was short-lived, but formed from a tropical wave. It became a Depression in the central Gulf and headed northwest toward the US coast, making landfall at nearly the same place as Claudette. Although only a Tropical Storm, Grace released 6” of rainfall over TX and LA.

Henri formed in the northeast Gulf from a tropical wave, but was immediately steered eastward across the central Florida peninsula, dumping 10” of rain in FL.

Isabel formed from a tropical wave out at 34°W and followed a classic track across the basin. It became the second major hurricane of the season at 41°W, then more notably, attained Category 5 status at 55°W… the first CAT5 in five years. This monster hurricane gradually weakened as it approached the US mainland, heading directly for North Carolina. Isabel made landfall between Capes Lookout and Hatteras as a CAT2 storm, then weakened to a CAT1 as it tracked inland across NC. It weakened further to a Tropical Storm as it passed over central Virginia and western Pennsylvania, finally dissipating over Lake Erie. This was a very destructive hurricane, with major storm surge flooding (6-8’ at places), 20” of inland rainfall, and causing widespread flooding and power outages in NC, VA, WV, MD, PA, and NY. Considering the impact this minimal hurricane and then tropical storm had on property and life along its path, it’s very fortunate that it weakened so much before making landfall; had it made landfall as a CAT4 or CAT5, it would have been catastrophic, surpassing the impact of Hurricane Andrew ’92 because of the large population it passed over.

Juan was yet another storm with tropical wave origins and a path of destruction. It formed southeast of Bermuda and tracked due north into Nova Scotia as a CAT2 hurricane. The eyewall went directly over Halifax causing extensive damage with 95kt gusts and large storm surge along the coast. This is the first time in 110 years that Halifax was directly hit by a hurricane eyewall.

Kate would become the third and last major hurricane of the season. It formed from a tropical wave in the central deep tropics, then tracked north, then northeast toward the Azores, then west toward Bermuda, then north toward Greenland. Although she lasted 12 days, the length of the track if straightened out would be the longest of the season.

Larry was a slow-motion system. Thirteen days after exiting Africa as an easterly tropical wave, it became a Depression in the Bay of Campeche. Then it slowly drifted south through the Bay and into Mexico.

Mindy lasted only a few days… formed from a tropical wave north of Hispaniola and tracked northward then eastward before dissipating.

Nicholas was the named storm to develop the furthest south, at 9°N, and so obviously, also from a tropical wave. It tracked northwest from the deep tropics, then dissipated northeast of the Lesser Antilles due to strong vertical wind shear.

Odette formed from a tropical disturbance and was very slow to organize as it drifted over the Bay of Campeche and parts of central America. Four days after the official end of hurricane season, it was upgraded to a depression, then a tropical storm shortly after, based on aircraft flights into the storm. It slowly headed northeastward toward Hispaniola and reached 55kts just prior to landfall, dumping 10” of rain over Jamaica, Haiti, and the Dominican Republic. Odette was the first named storm to form in the Caribbean during December since records began in 1871.

Lastly, Peter formed from a subtropical Low west-northwest of the Cape Verdes. This small storm was very quick to spin up, and already had an eye by the first advisory, but operationally was not made a hurricane (could be upgraded in the post-season re-analysis). Peter was absorbed by a mid-latitude trough just one day after forming. This was the first time since 1887 that two named storms formed during December in the Atlantic.


On September 6-8, there were three active named storms... Fabian, Henri, and Isabel. There were many examples of two named storms being present at the same time. Also of great interest is the large number of storms with easterly tropical wave origins; 12 out of 16!

The 2003 season, with 16 named storms, ranks #3 in recorded history for activity in the Atlantic, only behind 1995 (19 named storms) and 1933 (21 named storms).
4. Landfall
----------------------------------------------------
There were ten landfalling storms this year... six of which made landfall on the U.S. Although Ana and Fabian did not technically make landfall, they passed close enough to Bermuda to make a significant impact. There were no major hurricane landfalls anywhere during the season… the last U.S. major landfall was Bret 1999.

The first column is the storm name, second column is the date of landfall, third column is the approximate time of landfall (UTC or Zulu), fourth column is maximum sustained winds (kts) at landfall, and the fifth column is the nearest location to landfall (preliminary storm-related deaths and damages are shown in parentheses).

STORM     DATE & TIME   WIND   LOCATION
--------- ------------- ------ ---------------
ANA       4/21           35    near Bermuda (2 deaths)
BILL      6/30 1800      50    Point au fer Island, LA, USA (4 deaths, $30 million)
CLAUDETTE 7/11 1000      80    Puerto Morelos, Quintana Roo, Mexico
          7/15 1500      70    Matagorda Island, TX, USA (3 deaths, $180 million)
TD7       7/26 0600      30    Sapelo Island, GA, USA
ERIKA     8/16 1100      65    Boca San Rafael, Tamaulipas, Mexico (2 deaths)
FABIAN     9/5          105    near Bermuda (8 deaths, $300 million+)
GRACE     8/31 1500      30    Port O’Connor, TX, USA
HENRI      9/6 1000      25    Clearwater, FL, USA
ISABEL    9/18 1700      70    Atlantic, NC, USA (30+ deaths, $1 billion+)
JUAN      9/29 0300      85    Pennant Point, Nova Scotia, Canada (4 deaths, extensive)
LARRY     10/5 0300      50    Comalcalco, Tabasco, Mexico (5 deaths)
ODETTE    12/6 2300      55    Cabo Beata, Jaragua, Dominican Republic


Hurricane Season 2004 begins June 1; the first names in the lineup are Alex, Bonnie, and Charlie. New names for the season are Gaston and Matthew, which replace Georges and Mitch whose names were retired in 1998. As an aside, there will likely be several new names in the 2009 list because of the death and devastation caused by so many of this year’s storms.


Please visit my tropical Atlantic headquarters.

09 December 2003

TS Peter forms in the central Atlantic...

Tropical Storm Peter, the 16th named storm of the season, has formed
from a subtropical Low WNW of the Cape Verde Islands at 15Z today.  Not
only was it VERY rare to have TS Odette form on Dec 4, but then to have
TS Peter form on Dec 9 is perhaps unprecedented (more to follow once I
get some stats, hopefully).

At 17Z, TS Peter was located at 20.3N 37.1W (800 miles WNW of the Cape
Verde Islands) and tracking NNE at 10kts.  Intensity is estimated to be
60kts and 990mb and already has an eye-like feature, so could be
upgraded to the 8th hurricane of 2003 later today.

The storm is expected to track northeast and be absorbed by a trough,
turning extratropical by Thursday.  So.... this will change the season
stats once again and once it's over I'll send out ANOTHER revised season
summary!  Sorry for the multiple summaries, but I don't think anyone
would have foreseen our season lasting into the middle of December!


Please visit my tropical Atlantic headquarters.

05 December 2003

Odette gets stronger...

Since yesterday morning, TS Odette has gotten better organized and more
intense, despite fairly high vertical shear.  The center has been hard
to track accurately... either it's masked by the CDO or it reforms under
new deep convection.  Regardless, it's only drifting northeast.

At 15Z today, Odette was located at 14.2N 74.2W and moving toward the
ENE at 4kts.  Aircraft-measured intensity is 45kts and 993mb and she
still appears to be getting better organized.  SSTs are still very warm
(28.5C), and the oceanic heat content is very high in this part of the
Caribbean, but vertical shear is not letting up much.  An aside... the
environmental SLP is about 1012mb now at this latitude, which is lower
than it would be in the summer; this helps explain the 993mb MSLP of
Odette and only 45kt winds.

A Tropical Storm Warning is in effect for Jamaica, Haiti, and much of
the Dominican Republic; a Tropical Storm Watch is in effect for the
eastern islands of the Bahamas.  Odette is forecast to strengthen some
more, but most likely not reach hurricane intensity.  She has now
contributed 1.0 additional Named Storm Days to the 2003 season, bringing
the total to 73.0.


Please visit my tropical Atlantic headquarters.

04 December 2003

TD20 forms in the western Caribbean...

At 15Z today, the area of disturbed weather I mentioned yesterday was
upgraded to Tropical Depression 20.  This was based on surface
observations in the area and the presentation on satellite.  An aircraft
will fly into the system later today to confirm or deny Tropical Storm
status.  If sustained winds in the surface circulation are at least
35kts, it will become TS Odette, the 15th named storm of the season
(although the season is officially over).

At 15Z, TD20 was located at 13.3N 76.3W and tracking NNE at 9kts. 
Intensity is 30kts and 1005mb.  The storm is expected to strenghten,
probably becoming a TS this afternoon, and to accelerate northward with
time.  This time of year, it would be very difficult for a tropical
system to survive outside of the deep tropics, so it should make the
extratropical transition during the weekend. 

A Tropical Storm Warning is in effect for all of the Haiti coast, and
Tropical Storm Watches are in effect for portions of the southern
Dominican Republic coast and the eastern islands of the Bahamas. 
Jamaica and Cuba could begin experiencing adverse weather today and
warnings might be issued for those areas as well.


Please visit my tropical Atlantic headquarters.

03 December 2003

Post-season activity might be brewing...

For nearly a week, I've been watching an area of disturbed weather in
the Bay of Campeche and over central America.  It has drifted a bit more
north into the west central Caribbean Sea now, and showing signs of
organization.

There is a broad circulation centered at about 13N 77W with significant
divergence aloft.  It is over 29C ocean temperatures, and in this part
of the basin, the warm water is deep, resulting in a high oceanic heat
content to fuel a potential storm.  Vertical shear could be the major
inhibiting factor (not a surprise in December especially)... strong
southwesterly flow aloft could keep it from organizing further.

A recon aircraft might investigate the system on Thursday to check for a
closed surface circulation.  If so, it would be come TD20, and if it
gets named, it will be Odette.

Recall this season started with Ana in the last week of April.  Only
fitting to maybe get Odette in the first week of December!  Officially,
hurricane season runs from June 1 to November 30.  I'll keep you posted
if anything happens with this.


Please visit my tropical Atlantic headquarters.