Chris Mooney is a freelance writer and the author of two books, 
My latest Storm Pundit column is up; it considers Dean in both Atlantic and global perspective. Some factoids:
1. Dean is the ninth most intense Atlantic storm by pressure, and six of the top ten (Wilma, Rita, Katrina, Mitch, Dean, and Ivan) have occurred in the past ten years.2. Dean is the strongest hurricane anywhere this year, and by far the strongest at landfall. It is the tenth category 4 or 5 hurricane globally and the 3rd Category 5.
You can read the rest of the "Storm Pundit" post here.
Here's an image, courtesy of Weather Underground, of Dean at landfall:
* Clarification: The title of this post should have noted that these are the most intense recorded hurricanes (measured by pressure). Certainly there were many intense hurricanes in past decades, centuries, millennia, etc, that could not have been so measured. The "Storm Pundit" post linked to makes this clear, but the title here should have as well.
Comments
You have to hope Dean drops his rain in the mountains before he reaches Mexico City (track I'm looking at).
Best,
D
Posted by: Dano | August 21, 2007 7:09 AM
Thanks for this, Chris.
I've got my own take, with pointers to and a brief quotation from your storm punditry, at my blog.
Click my name to read "Hurricane Dean's Global Warning (Note Spelling, n not m)."
Posted by: Fred Bortz | August 21, 2007 10:12 AM
Central pressure measurements in the past were only possible if and when the hurricane made landfall at a location where pressure measurements could be made. Subsequently, aircraft measurements were made at sea, but those measurements were necessarily sparse, and probably often missed the peak. Now they estimate central pressure from satellite pictures, which means it's a continuous estimate. So the statistic is hopelessly biased.
The measured maximum of any time-varying function will depend on how often you measure. Plot central pressure at landfall for hurricanes hitting the US, and you would get better statistics.
Posted by: Gerard Harbison | August 21, 2007 11:30 AM
Following up my earlier comment: the appended link has estimated central pressure at landfall for hurricanes hitting the continental United States in the last 150 years or so.
http://www.nhc.noaa.gov/pastint.shtml
Including the 2005 hurricanes, only one hurricane in the last decade had a central pressure at landfall in the US in the top ten (Katrina, 920 mb, 2005). There were three in the top twenty (Charlie and Rita added) and four in the top thirty (Ivan added). That is a slight excess over the expected 150 year average of two in the top 30, but I doubt it's statistically significant.
This isn't a perfectly unbiased data set, but it's better than what you're using.
Posted by: Gerard Harbison | August 21, 2007 2:44 PM
Gerald,
I'm not sure, do you think I'm unaware of this?
All hurricane data is shot through with these types of problems. We have to take the best data, and the best theory, and see where it is that together they point.
I contend that the reasonable position, when regarding both sets of findings, is to worry. Not to state anything definitively, but to be concerned.
Posted by: Chris Mooney | August 21, 2007 3:30 PM
Your title says: "Six of the Ten Most Intense Atlantic Hurricanes Occurred In the Past Decade". If you are aware that's almost certainly not the case, well, um, aren't there some ethical issues here?
Posted by: Gerard Harbison | August 21, 2007 4:03 PM
I probably should have used the word "recorded" but if you read the actual post I'm linking to, you see I explain all the uncertainties.
Posted by: Chris Mooney | August 21, 2007 4:10 PM
Still, just to be safe, I added a clarification to this post. Obviously, I am talking about *recorded* hurricanes.
Posted by: Chris Mooney | August 21, 2007 4:31 PM
Satellites do not take continuous photos; US GOES West and East take a picture every 30 minutes. (Some aerial recon data is continuous, depending on the instrument, but only for a few hours on each visit. Dropsondes, considered the most accurate way to measure minimum central pressures do not make continuous measurements.) More importantly, the Dvorak method requires observing a storm for at least 3 hours. Satellite based estimates cannot achieve more than 8 samples per day. For minimum central pressure, 8 Dvorak estimates a day is more than the 2-3 dropsonde measurements per flight, but it is not as much more as your claim of 'continuous' implies.
Finally - satellite methods require (among other things) measuring the eye temperature, and thus, accurately imagining the eye with IR photography. Because satellites have limited resolution, satellite methods often underestimate TCs with small eyes, and those undergoing rapid intensification. For example, the highest Dvorak satellite classification recorded for Wilma of 2005 was 6.0 , corresponding to 115 kt sustained surface winds (borderline category 4 strength) and 948 mb minimum central pressure. Yet aerial recon data led analysts to estimate Wilma's sustained surface winds at 160 kts, and minimum central pressure at 882 mb.
It is true that the numbers in the top 10 list differ significantly in their sources (thus it is a table of apples and oranges), and it is generally agreed that the older data is more prone to underestimate storms than overestimate storms (but for a counter example, see Landsea's paper on the effect of using mis-calibrated cup-anemometers to measure wind speeds. Many old cup-anemometers were found to overestimate wind speeds by up to 50% .), but as long as we are talking about minimum central pressures in the Atlantic, or the NE Pacific, it is better aerial recon that is to blame, not satellites.
In closing - I do not know of any hurricane scientist who uses minimum central pressures to look for long term trends. Wind speeds have their problems, but not nearly so many.
Posted by: llewelly | August 21, 2007 7:28 PM
Gerard Harbison:
US landfalling data is a tiny fraction of total Atlantic hurricane activity. (Which itself is only 11% of global activity.)
Posted by: llewelly | August 21, 2007 8:09 PM
Thanks for the correction, Chris.
Posted by: Gerard Harbison | August 22, 2007 1:06 PM