“In the Above-normal case, ACE median ~ 1.15*ACE Medain, whereas, in the Below-normal case, 0.65*ACE ~ 0.74*ACE Median.”

should read:

“In the Above-normal case, ACE Mean ~ 1.15*ACE Median, whereas, in the Below-normal case, 0.65*ACE Mean ~ 0.74*ACE Median.”

Sorry about that …

“Measured over the period 1951–2005 for the Atlantic basin:

Median annual index: 89.5
Mean annual index: 102.3

A season’s ACE is used to categorize the hurricane season by its activity. NOAA categorisation system[3] divides them into:

Above-normal season: An ACE value above 103 (115% of the current median), provided at least two of the following three parameters exceed the long-term average: number of tropical storms (10), hurricanes (6), and major hurricanes (2).
Near-normal season: neither above-normal nor below normal
Below-normal season: An ACE value below 66 (74% of the current median):

In the Above-normal case, ACE median ~ 1.15*ACE Medain, whereas, in the Below-normal case, 0.65*ACE ~ 0.74*ACE Median. This stikes me as rather odd. I would have thought the boundaries would have been more symmetrical. Can anyone help me, or direct be to a reference source that might help me, understand the reasoning for defining the categories this way?

In the northeast, the NWS dropped the temperature requirement since coastal storms usually bring warm temps.

Is there a difference in photo technology and filtering, or is there really that much less cloud cover?

Another important factor is the depth and configuration of the continental shelf just off a given target area.

How about one storm that, in a week or so, brought hurricane conditions to every one of the Greater Antilles, and then to every state on the Atlantic coast of the U.S. from Florida (both coasts) to Maine?

That was Hurricane Donna in 1960–a year, by the way, with an anemic ACE.

The opposite is true for the Southwest Pac, which leads me to wonder whether there are ACE figures available for the current typhoon season. The global ACE and its adventures over the past century would also be quite relevant in trying to grasp such cyclic patterns as can be discerned (Leif Svalgaard has wised me up on cyclomania as applied to systems with a significant chaotic input).

Isn’t Texas still in the Union? How many missing and presumed dead on Galveston Island?

It doesn’t take a Cat 5 or even a major hurricane to cause grief

Floyd didn’t look so purdy by the time it huffed and puffed its way up here to 40 N, but it dumped 15 inches of rain in as many hours on central New Jersey, and the ensuing Floydian flood (not Floydian slip) knocked out a major water filtration plant for two weeks.