Largest Atlantic Hurricane

[Ptarmigan]

Don't know how reliable it is. Here are the largest Atlantic hurricanes.
Rank Hurricane Season Size HSI Diameter (in miles)
1 Ike 2008 25 600 mi
2 Gilbert 1988 24 520 mi
3 Mitch 1998 23 500 mi
4 Wilma 2005 22 475 mi
5 Isabel 2003 22 470 mi
6 Floyd 1999 22 460 mi
7 Katrina 2005 22 455 mi
8 Gabrielle 1989 20 445 mi
9 Carla 1961 18 420 mi
Ivan 2004 18 420 mi
Gustav 2008 18 420 mi
10 Fran 1996 16 405 mi

The largest hurricane is Ike, which tragically ravaged our area. I didn't know Mitch was larger than Katrina. Wilma was much larger than Katrina. Turns out Carla is smaller than Katrina.

http://en.wikipedia.org/wiki/Hurricane_Ike

[Hurricanehink]

I wouldn't trust Wikipedia on this one, since the person who wrote it is very new, and likewise the template from which the data is from is also very new and unsourced.

[Derek Ortt]

the list is a pile of cow dung

[jinftl]

If you define 'largest hurricane' as having the largest diameter of overall tropical storm force winds, Wilma at its widest beats out Ike.

At Ike's widest expanse of tropical storm force winds:
HURRICANE IKE ADVISORY NUMBER 45
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008
400 AM CDT FRI SEP 12 2008
IKE REMAINS A VERY LARGE TROPICAL CYCLONE...AND
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 275 MILES...445 KM.

At Wilma's widest expanse of tropical storm force winds:
HURRICANE WILMA ADVISORY NUMBER 42
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT TUE OCT 25 2005
...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 430 MILES...695 KM.


If you define 'largest hurricane' as having the largest diameter of hurricane force winds, Katrina had a larger expanse of sustained hurricane force winds than Ike at her largest:

At Ike's widest expanse of hurricane force winds:
HURRICANE IKE ADVISORY NUMBER 45
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008
400 AM CDT FRI SEP 12 2008
IKE REMAINS A VERY LARGE TROPICAL CYCLONE. HURRICANE FORCE WINDS
EXTEND OUTWARD UP TO 120 MILES...195 KM...FROM THE CENTER...

At Katrina's widest expanse of hurricane force winds:
HURRICANE KATRINA INTERMEDIATE ADVISORY NUMBER 26B
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM CDT MON AUG 29 2005
KATRINA IS A VERY LARGE HURRICANE. HURRICANE FORCE WINDS EXTEND
OUTWARD UP TO 125 MILES FROM THE CENTER...AND TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 230 MILES

[Ptarmigan]

I was always under the impression that Carla was larger than Katrina. I was actually surprised to find that Mitch was really large. I know it was large, but not that large.

[jinftl]

From Chris Hebert, one of the developers of the HSI (Hurricane Severity Index)...straight from the 'horse's mouth'....Ike had an HSI of 30 at landfall....not even in the top 10 highest HSI....not sure what the wikipedia article is referencing for highest HSI, since one of the creators of the HSI says nothing resembling the wikipedia data at all....scary that anyone can 'write history' on wikipedia. According to Hebert the storms with the top 5 highest HSI are (from higest): Carla, Gilbert, Katrina, Ivan, Opal

After the 2005 season, Bob and I came up with a new hurricane scale to supplement (or replace) Saffir-Simpson. What we came up with is an index that not only considers a tropical cyclone’s maximum sustained winds, but also the size of its wind field. It’s a 50-point scale – 25 points are allotted for the maximum sustained winds, the other 25 points are assigned according to the size of the wind field. I won’t go into all of the details here, you can read about the HSI in great detail at the two links below:

http://impactweather.com/pdf/hsi_explained.pdf - a full explanation of HSI

http://impactweather.com/pdf/hsi.pdf - a full description of how HSI is calculated

We can graphically depict some well-known past hurricanes to see where they rank on the HSI:

On the graphic, a tropical cyclone’s intensity is represented by the horizontal scale. A tropical cyclone’s wind field size is represented by the vertical scale. The top right of the graphic represents very large and powerful Category 5 hurricanes. The lower left of the graphic would represent relatively small and weak tropical storms. Yes, even tropical storms are classified with the HSI, as opposed to the Saffir-Simpson scale which only classifies hurricanes. On the HSI, Ike scored 30 points at landfall – 10 for its Category 2 winds but 20 out of a possible 25 points for the size of its wind field. It was those 20 size points which was the reason for Ike’s extremely high and extensive storm surge.



http://www.pennwellblogs.com/tropics_watch/

[Aslkahuna]

The Great Atlantic Hurricane of 1944 was a tad on the large size as well.

Steve

[MiamiensisWx]

Note that the 1926 Miami hurricane attained an exceptionally high IKE value, based on intensity points. Note that the HURDAT lists a landfall intensity of 115 kt (135 mph)/935 mb at landfall in south Florida. I have extensively discussed the fact that HURDAT contains numerous errors and incorrect (grossly high/low) intensity estimates prior to the 1980s/1990s. Recently, a preliminary reanalysis has raised the intensity of the 1926 TC to 125 kt (145 mph)/933 mb in south Florida. Sustained (1-min) winds of hurricane intensity extended from the upper Florida Keys to Palm Beach County, which is a distance in excess of 70 miles.

Here is an article on the 1926 TC's size:

http://www.geocities.com/capeverdewave/Storm61926_news1.jpg

Note that the 1928 Okeechobee hurricane, which made landfall on West Palm Beach, was even larger than the 1926 TC. Its intensity has been estimated near 125 kt (145 mph)/929 mb at landfall. The radius of 1-min hurricane force winds also exceeded 70 miles. According to Eliot Kleinberg's Black Cloud: The Deadly Hurricane of 1928, an interview with Brian Jarvinen revealed that "the eye was 25 to 30 miles across." At the time, Richard Gray, a meteorologist at the U.S. Weather Bureau's Miami office, stated that "hurricane force winds were felt from just north of Hollywood to somewhere north of Jupiter-in other words, across two Florida counties covering about 75 miles of coast. Gray said that 'serious structural damage' from the storm stretched from Gomez, a now-abandoned settlement north of Jupiter, to Pompano Beach, a distance of 60 miles. Damage was reported as far north as Vero Beach and as far south as Miami." The strongest winds occurred from Jupiter to Stuart, but severe damage occurred from Pompano Beach to Gomez (north of Jupiter). Gray estimated that the diameter of the storm reached 500 miles, which is comparable to Hurricane Floyd of 1999.

[HurricaneBill]

Wasn't the Great New England Hurricane of 1938 also very large?

[Ptarmigan]

Wasn't the Great New England Hurricane of 1938 also very large?

I wouldn't be surprised if the Great 1938 was large, especially the fact once it goes past the Carolinas, hurricanes tend to get larger.

[wxman57]

Wasn't the Great New England Hurricane of 1938 also very large?

I wouldn't be surprised if the Great 1938 was large, especially the fact once it goes past the Carolinas, hurricanes tend to get larger.

Unfortunately, prior to the era of modern recon with Doppler radar, SFMR and dropwindsondes, actual data on wind field size is pretty poor. It's likely that the 1938 hurricane was undergoing extratropical transition as it accelerated northward at over 50 mph, caught in the jet stream along a cold front. Such storms can have a very large wind field, as Wilma did once it passed Florida.

[thegreatdr]

This is normally why people like to use ROCI, which is easier to determine than gale radii for older storms.

[wxman57]

One thing you have to be careful of when reading the NHC public advisories on wind radii extending out "up to XXX miles from the center" is not to make an assumption that these radii extend outward the same distance in each quadrant. For example, TS winds could extend outward 250 miles from the center in the eastern half but only 50 miles from the center (or not at all) in the western half. So the diameter of TS winds isn't necessarily 500 miles, it could be 250 miles. You have to look at the marine advisory for radii in each quadrant of a storm. Most storms are asymmetrical.

[HurricaneRobert]

Those large ET-transitioning storms are some of the least symmetric, so I don't like to include them on lists of the largest tropical cyclones. We should have a different label for them besides tropical cyclones.

[Aslkahuna]

However, those ET transitioning systems are still tropical as long as they have a warm core center.

Steve

[Tampa Bay Hurricane]

The hurricanes with the largest wind radii appear to be those
that have a longer time over very warm waters and favorable
conditions (more opportunity for eyewall replacement cycles)
as well as those that are transitioning to extratropical
systems.

[wxman57]

The hurricanes with the largest wind radii appear to be those
that have a longer time over very warm waters and favorable
conditions (more opportunity for eyewall replacement cycles)
as well as those that are transitioning to extratropical
systems.

Concerning hurricane size, there are several factors that contribute, I don't think that duration over warm water is as much of a factor as other environmental conditions.

1. Extent of moist environment - big hurricanes develop in expansive areas of high moisture. Small hurricanes develop in smaller pockets of moisture between dry airmasses.

2. Interaction with land - just about any time a hurricane interacts with land and then moves back over water, its wind field increases significantly. This is mostly due to conservation of energy. Low-level winds are reduced, wind field expands to compensate. We certainly saw that with Ike last year after it crossed Cuba each time, and Wilma was another good example after interacting with the Yucatan for 24-36 hours.

3. Eyewall replacement cycles - these do result in at least a temporary increase in the wind field size.

4. Extratropical transition - typically results in quite a significant increase in wind radii. Extratropical storms are generally much larger than tropical cyclones.