30 November 2005

Epsilon strengthens...

Today is the last day of the official hurricane season, but apparently 
nobody told Epsilon, which is still out there and going strong.

The satellite presentation today is beautiful; there's symmetric 
outflow, nice banding features, and an eye/eyewall forming.  This visual 
appearance plus some help from other remote sensing techniques gives an 
estimated intensity of 55kts and 993mb.  It could strengthen further 
before transitioning to an extratropical cyclone this weekend... 
possibly reaching hurricane status.  It's tracking W at 8kts, but should 
begin a northeasterly movement tonight.  As of 15Z, it's located at 
30.7N 53.9W, or about 10 degrees ESE of Bermuda.

As a quick season wrap-up, we've seen 26 storms reach Tropical Storm 
intensity or higher.  13 of those reached Hurricane status, and 7 of 
those reached Major Hurricane status (CAT3+).  The "average" numbers are 
10 Tropical Storms, 6 Hurricanes, and 2 Major Hurricanes.  Taking into 
account the numbers of storms and longevity of them compared to average, 
this season was over 2.5 times more active than an average season 
(257%).  In the Atlantic, we witnessed the highest number of named 
storms in recorded history (26), the lowest pressure in recorded history 
(882mb), and the costliest disasters in US history ($100 billion+).  
There are scores of other records too.  I'll eventually be sending out 
my full summary, but this is a good teaser!  Stay tuned!

Please visit my tropical Atlantic headquarters.

29 November 2005

Epsilon forms in central Atlantic...

As the 2005 tropical Atlantic season persists, Epsilon, the 26th named 
storm, formed this morning.  It's located about 14 degrees east of 
Bermuda in the north central part of the basin and its latest satellite-
estimated intensity is 45kts and 993mb.  It is heading W at 7kts.  SST 
under the system is about 25C and vertical wind shear is about 15kts 
from the southwest.

The forecast is for gradual strengthening (largely owing to decreasing 
shear), perhaps reaching hurricane status within the next couple of 
days, then transitioning to an extratropical cyclone.  It is expected to 
drift westward for the next 1-2 days, the zip off to the ENE as it gets 
caught up in the mid-latitude westerlies.

As an aside, Delta became an extratropical cyclone and hit the northwest 
coast of Africa and the Canary Islands as a very potent storm.  It was a 
named tropical storm for 5 days.

The NTC for 2005 is now 257%.  The season has not been one to break 
records, it has been one to shatter them.  As most of you know, I send 
out a season summary each year at the end of the season.  I still plan 
on doing this, but it probably won't come out on Dec 1.  Eventually...

Please visit my tropical Atlantic headquarters.

An Old Record Tied

From Gary Padgett:
The formation of TS Epsilon in the Atlantic ties the
record for the most TS/HU forming post-30 September.
In 1887 there were 9 post-Sept TCs---six forming in
October (as in this year), and after a quiet month,
a little "mini season" in late Nov/early Dec, whereby
1 HU formed at the end of Nov, and another HU and
as TS formed during the first week of Dec, all in the
general region just north and northeast of the Greater
Antilles.   The two hurricanes eventually recurved
into the Atlantic, but the final one, a TS, formed
east of the Leewards and pursued an very unusual
WSW track across the entire Caribbean, eventually
moving into Costa Rica--the only TS on record to
make landfall in that country.
The second highest number of post-30 Sept TCs
was just 4 years ago, in 2001, with 7 named storms
forming in Oct and Nov.   If we can get a Zeta
during Dec, we can set yet another record for
the 2005 season.
Please visit my tropical Atlantic headquarters.

23 November 2005

TS Delta forms in the central Atlantic...

A strong subtropical storm has transitioned to tropical, and has 50kt 
sustained winds and a 982mb MSLP, making it TS Delta, the 25th named 
storm of this unprecedented season.  It is well away from land, located 
at 25.9N 40.5W and tracking SSE at 8kts.  The convection and outflow are 
very healthy, and while the SSTs are only 25C or so, the tropopause 
temperature is colder than average too, so the temperature DIFFERENCE 
between the inflow and outflow levels is still enough to support a 

The forecast calls for some strengthening, perhaps reaching hurricane 
status Thursday night into Friday morning, then becoming extratropical.  
The track is northerly at first (hence being nudged equatorward toward 
warmer SSTs) then southerly back into the mid-latitudes.

The NTC is now 253%.  If it is upgraded to a hurricane tomorrow morning 
(just supposing), the NTC would jump to about 256%.

Please visit my tropical Atlantic headquarters.

18 November 2005

TD27 becomes Gamma in this unprecedented season...

On Nov 13, an area of disturbed weather in the far eastern Caribbean Sea 
was upgraded to TD27, but remained poorly organized.  On Nov 16, the 
final advisory was written on it as it degenerated to an open wave.  
However, over the past couple of days, it has been left to fester in the 
western Caribbean Sea and has continually gotten better organized.  An 
aircraft recon flight into this afternoon found not only a closed 
circulation, but tropical storm force winds, making it the 24th named 
storm of the season, Gamma.

At 22Z, TS Gamma was located 16.4N 85.6W and creeping WNW at 4kts.  
Intensity measured by the aircraft is 40kts and 1006mb.  Its future is 
not too bright, as vertical wind shear impinges on it and it drifts 
closer to land.  However, the forecast track brings it northwest toward 
Cozumel/Cancun, then recurves and heads northeast toward the southern FL 

With this addition, the season's NTC stands at 251% (recall that an 
"average" entire season is defined as 100%).

Please visit my tropical Atlantic headquarters.

03 November 2005

perspectives on the 2005 ATL season

From Gary Padgett: 
One perspective on this season which I've found very interesting
is that the superabundant activity has been largely due to the
incredible amount of activity in July and October.   I've calculated
the Net Tropical Cyclone activity index (NTC) per Dr. Gray's
formula for each month from 1950-2004, and for the months
of this hurricane season.

(The NTC is an average of the six "cardinal" parameters---number of
named storms (NS), hurricanes (H), intense hurricanes (IH), and the
total number of days accumulated for each intensity level (NSD, HD,
IHD)---with each expressed as the percentage of the long-term average
over some baseline period.   The NTC for each month is calculated
by dividing that month's total NS, H, etc by the annual averages of
each parameter, then averaging the six percentages.)

The following table gives the average monthly NTC for the months
June - October for the period 1950-2004, followed by the 2005
NTC for that month:

Month     Avg. NTC    2005 NTC
Jun             2%          4%
Jul             4%         64%
Aug            25%         39%
Sep            48%         70%
Oct            16%         63%

The core months of Aug/Sep produced a total of 10 NS
with 7 H for a combined NTC of 109%.    While having
two hurricanes of the intensity of Katrina and Rita was
very unusual, otherwise the activity of the two main months
wasn't particular all that remarkable.   Many years have
had Aug+Sep totals of 10 NS and 7 H---last year had
12 NS and 8 H with an NTC of 208%.

October's is the highest NTC since 1950 (61%) and is
only the 3rd October on record to produce 6 NS, the
others being 1950 and 1887.

July's NTC of 64% wildly exceeds the previous high
July NTCs of 26% (1996) and 24% (1966), and the
5 NS forming during the month is a new record.

Please visit my tropical Atlantic headquarters.