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 
hurricane.

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.

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 
peninsula.

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.

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.