The hurricane season is officially over, so it's time for the annual Hurricane Season Summary. I sent out about 60 updates to this mailing list (which has grown from a small handful in 1998, to 27 in 1999, to 213 in 2000!) over the past 6 months; now it's time for the final one. I'm going to use the same format as I did last year, so it will look very familiar if you were a subscriber last year. I will keep the same basic outline: 1) the Saffir-Simpson Scale, 2) Lifetimes and Intensities, 3) Climatology, and 4) Landfall.
As usual, my data and typing could contain errors, so if you see a mistake, please point it out to me.
Saffir-Simpson Scale of Tropical Cyclone Intensity
------------------- ---------- ------------------
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
1. Lifetimes and Intensities
----------------------------------------------------
NAME DATES OF MAX WIND MIN PRES
ACTIVITY (mph) (mb)
-------- --------------- ------------ -------------
TD1 07 JUN - 08 JUN 25 1008
TD2 24 JUN - 25 JUN 30 1006
ALBERTO 04 AUG - 23 AUG 110 950 (N,H,M)
TD4 09 AUG - 11 AUG 30 1009
BERYL 13 AUG - 15 AUG 45 1007 (N)
CHRIS 18 AUG - 19 AUG 35 1008 (N)
DEBBY 19 AUG - 24 AUG 65 995 (N,H)
ERNESTO 02 SEP - 03 SEP 35 1008 (N)
TD9 09 SEP - 09 SEP 30 1007
FLORENCE 11 SEP - 17 SEP 70 985 (N,H)
GORDON 14 SEP - 18 SEP 65 981 (N,H)
HELENE 15 SEP - 22 SEP 60 986 (N)
ISAAC 21 SEP - 01 OCT 120 943 (N,H,M)
JOYCE 25 SEP - 02 OCT 80 975 (N,H)
KEITH 28 SEP - 06 OCT 115 942 (N,H,M)
LESLIE 05 OCT - 07 OCT 40 1006 (N)
MICHAEL 17 OCT - 20 OCT 85 965 (N,H)
NADINE 19 OCT - 22 OCT 50 999 (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 most up-to-date best-track data available from the NHC; this is NOT what you may find on many website archives (yet).
2. Climatology and Statistics
----------------------------------------------------
The average annual number of tropical disturbances (over the past 54 years) is:
9.9 named storms
5.9 hurricanes
2.5 major hurricanes
This year, the numbers were generally well above that average (which has recently been the trend, except 1997)
14 named storms (12 in 1999)
8 hurricanes (8 in 1999)
3 major hurricanes (5 in 1999)
A fairly unique aspect of the past season was that there were 4 Tropical Depressions that never reached Tropical Storm status. There are typically only one or two such storms per season, so it seems that despite the above-average activity, there was something that inhibited intensification. A common theme for several weeks was vertical wind shear. For some unknown environmental reason, many storms suffered from high shear resulting in a) the large number of unnamed TD's and b) a large number of storms with exposed Low Level Circulation Centers at some point in their lifecycle.
For the second year in a row, the Atlantic Basin never experienced a CAT5 hurricane. In fact, the last CAT5 hurricane in the Atlantic Basin was Mitch in October 1998.
There were a total of 62.75 named storm days (days during which a named storm was present). 31.5 of those days were "hurricane days", and 5.25 of those days were "intense hurricane days". This is 134% of the climatological mean, i.e., this season was about 1/3 more active than the "normal" season. The average numbers (1944-2000) are 46.6 named storm days, 23.9 hurricane days, and 4.7 intense hurricane days.
Here is a summary of highlights (VERY brief):
Alberto not only started the season off, but was also the longest-lived hurricane in August ever (third longest-lived in the basin for all times of year). He had a unique track in that he formed south of the Cape Verde Islands, began recurving at about 59W, completed a giant loop in the north central Atlantic that lasted for one week, then headed off toward Iceland.
Beryl was not too exciting... she formed in the central Gulf of Mexico then headed west into the northern coastal areas of Mexico, causing one death there.
Chris barely made the list... he was weak to start, achieved minimal TS status, then was sheared apart.
Debby was also fairly weak, but lasted a bit longer. She formed out at 45W to the east of Barbados, then passed over the Greater Antilles. The journey near the mountainous islands there was her downfall... she dissipated near the southeast tip of Cuba.
Ernesto was basically an insignificant storm. He was short-lived, never reached hurricane strength, and never got close to land. His entire track was located to the east and northeast of the Lesser Antilles.
Florence was the first of three storms to develop along a mid-latitude trough this season. She formed 400 miles SSE of Cape Hatteras, almost completed a small loop, then was forced northeast, eventually passing just east of Newfoundland where she caused 2 deaths.
Gordon formed on the east coast of the Yucatan Peninsula (causing 19 deaths in Guatemala), crossed over the tip of the peninsula, then headed NNE toward Florida. He made landfall at the northwest tip of the Florida Peninsula, but caused no deaths in the US.
Helene formed out at 54W to the east of Gaudeloupe. She dissipated before reaching the Leeward Islands, then reformed just south of Cuba. She then continued to travel northward, destined to make landfall on the panhandle of Florida.
Isaac formed south of the Cape Verde Islands and followed Alberto's track very closely (except the loop). Like Alberto, Isaac also became a major hurricane and did not threaten land at all.
Joyce formed in the eastern Atlantic and headed west. She made a very unusual dip to the south before reaching the Windward Islands, passed over Tobago, then dissipated just off the South American coast.
Keith formed just off the coast of Honduras and began to head WNW toward Belize. During that short journey, he intensified very quickly to a CAT4 storm. Unfortunately, it was at that point that he stalled right over the Belize coast. After sitting there for over two days, he moved inland over the Yucatan Peninsula, entered the Bay of Campeche, then made landfall again near Tampico, Mexico. Keith caused 17 deaths in several countries.
Leslie was the second storm to form along a mid-latitude trough. She formed off the northeast coast of the Florida Peninsula and immediately moved away from the coast. The disturbance that was pre-Leslie caused 3 deaths in southern Florida due to flooding.
Michael was the third storm to form along a mid-latitude trough. He formed southeast of Bermuda and was also whisked toward the northern Atlantic by the trough. He made direct landfall on Newfoundland as a CAT1, but caused no deaths there.
Finally, Nadine was very much like Ernesto in that she did not last long, was weak, and was never near any land. Her track covered an area to the east of Bermuda.
On 19Aug, there were three named storms... Alberto, Chris, and Debby. Tied for simultaneous activity was mid-September. From Sep15 to Sep17, there were three named storms in the Atlantic again, Florence, Gordon, and Helene. Not too outstanding, but these were the most active time frames of the season. There were many examples of two named storms being present at the same time. It is also interesting to note that there were no named storms during June, July, or November.
3. Landfall
----------------------------------------------------
There were 8 landfalling storms this year... only 3 of which made landfall on the US. Compare this to last year, when 5 of 10 landfalling storms made landfall on the US. It is also interesting to note that only LA and FL were hit, leaving the other 16 coastal (Gulf, Atlantic) US states unscathed. Also, there were no landfalls on the east coast of the US.
The first column is the storm name, second column is the date of landfall, third column is the approximate universal (UTC) time of landfall, fourth column is max winds (kts) at landfall, and the fifth column is the nearest location to landfall.
DEBBY 8/22 0600 65 Barbuda
8/22 1000 65 St. Martin, St. Barthelemy
8/22 1500 65 British Virgin Islands
TD9 9/9 0600 30 Cameron, LA, USA
GORDON 9/18 0300 60 Cedar Key, FL, USA
HELENE 9/20 1300 25 Cabo Corrientes, Pinar del Rio, Cuba
9/22 1000 45 Navarre, FL, USA
JOYCE 10/1 1000 35 Roxborough, Tobago
KEITH 10/3 0300 60 Ambergris Cay, Belize ##
10/5 1800 80 Lomas del Real, Tamaulipas, Mexico
MICHAEL 10/19 2300 80 Francois, Newfoundland, Canada
## A note about Keith's first landfall: Although the intensity at official landfall was fairly weak, the storm stalled for 24+ hours just miles off the coast of Belize as a CAT4 storm with 115kt winds. The 80kt winds at landfall is not representative of the damage and deaths he caused.
New this past season was a Tropical Atlantic Satellite Sector webpage I created (www.mcwar.org/gallery/tropics/sectors.html). Thanks to all who tested it during the laborious construction phases. I know it came in handy for me, and I received several kind comments from other tropical enthusiasts during the past few months.
Hurricane Season 2001 begins June 1, the first names in the lineup are Allison, Barry, and Chantal.
Please visit my tropical Atlantic headquarters.
No comments:
Post a Comment