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Atlantic Hurricanes: Reanalyzed


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Chris Landsea sent out an eMail today Re: a new masters thesis:

"A Reanalysis of the 1944-1953 Atlantic Hurricane Seasons - The First Decade of Aircraft Reconnaissance" by Andrew Hagen at the University of Miami.

Since Chris Landsea and another dude from the HRD have approved it, it's reasonable to assume that the findings of this report will be seriously considered by the best-track committee when they evaluate these years.

Of particular interest: a whopping four FL landfalls (1945, 1948, 1949, and 1950) were upgraded from Cat 3 to Cat 4! Adding in the 1947 "Fort Lauderdale" cyclone makes five Cat-4 landfalls for FL in six years! I've always thought of the 1940s as a huge decade for FL 'canes, but that is just a ridiculous amount of heavy action in a half decade.

I'm excited that one of my favorite cyclones-- King 1950-- was upgraded to a Cat 4 for its FL landfall. :wub: This extremely tight microcane deepened rapidly just before crossing the coast near Miami Beach, and the RMW of only 5 mi suggests the 955 mb would support winds of 115 kt. A crazy-azz cyclone-- like our version of Cyclone Tracy. From the report:

Hurricane King of 1950, which made landfall at Miami, FL on October 18 at 05Z, is upgraded from a Category 3 to a Category 4 at landfall. A central pressure of 955 mb was observed in Miami. The maximum recorded 1-min wind at the Downtown Miami Weather Bureau Office was 106 kt (elevated) and 70 kt was the highest 1-min wind experienced at the airport. The RMW was a tiny 5 nmi. A central pressure of 955 mb equals 108 and 105 kt according to the intensifying subsets of the Brown et al. (2006) pressure-wind relationships for south and north of 25N latitude respectively. The climatological RMW value from Vickery et al. (2000) for this latitude and central pressure is 17 nmi (more than three times larger than the analyzed RMW of 5 nmi). Reanalysis methodology from Landsea et al. (2008) states that for landfalling U.S. tropical storms and hurricanes for which the RMW is significantly smaller (>50%) than the climatological value, 10 kt should be added to the pressure-wind relationship. A 115 kt landfall intensity is analyzed. King deepened by 33 mb during the 14 hr immediately prior to landfall at Miami (max 1-min wind is analyzed to have increased 45 kt in 12 hr).

In other news... The Great Atlantic Hurricane of 1944 has been downgraded to a Cat 2 for the entire coast (NC, VA, NY, RI), as I have seen in other papers. It was a large storm and a big event for this region, but it just wasn't as strong as has always been believed. That 116 kt sustained from Cape Henry, VA, was either elevated or dismissed as unreliable.

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Chris Landsea sent out an eMail today Re: a new master's thesis:

"A Reanalysis of the 1944-1953 Atlantic Hurricane Seasons - The First Decade of Aircraft Reconnaissance" by Andrew Hagen at the University of Miami.

Since Chris Landsea and another dude from the HRD have approved it, it's reasonable to assume that the findings of this report will be seriously considered by the best-track committee when they evaluate these years.

Of particular interest: a whopping four FL landfalls (1945, 1948, 1949, and 1950) were upgraded from Cat 3 to Cat 4! I've always thought of the 1940s as a huge decade for FL 'canes, but that is just a ridiculous amount of heavy action in a half decade.

I'm excited that one of my favorite cyclones-- King 1950-- was upgraded to a Cat 4 for its FL landfall. :wub: This extremely tight microcane deepened rapidly just before crossing the coast at Miami Beach, and the RMW of only 5 mi suggests the 955 mb would support winds of 115 kt. A crazy-azz cyclone-- like our version of Tracy. From the report:

Hurricane King of 1950, which made landfall at Miami, FL on October 18 at 05Z, is upgraded from a Category 3 to a Category 4 at landfall. A central pressure of 955 mb was observed in Miami. The maximum recorded 1-min wind at the Downtown Miami Weather Bureau Office was 106 kt (elevated) and 70 kt was the highest 1-min wind experienced at the airport. The RMW was a tiny 5 nmi. A central pressure of 955 mb equals 108 and 105 kt according to the intensifying subsets of the Brown et al. (2006) pressure-wind relationships for south and north of 25N latitude respectively. The climatological RMW value from Vickery et al. (2000) for this latitude and central pressure is 17 nmi (more than three times larger than the analyzed RMW of 5 nmi). Reanalysis methodology from Landsea et al. (2008) states that for landfalling U.S. tropical storms and hurricanes for which the RMW is significantly smaller (>50%) than the climatological value, 10 kt should be added to the pressure-wind relationship. A 115 kt landfall intensity is analyzed. King deepened by 33 mb during the 14 hr immediately prior to landfall at Miami (max 1-min wind is analyzed to have increased 45 kt in 12 hr).

In other news... The Great Atlantic Hurricane of 1944 has been downgraded to a Cat 2 for the entire coast (NC, VA, NY, RI), as I have seen in other reports. It was a large storm and a big event for this region, but it just wasn't as strong as has always been believed. That 116 kt sustained from Cape Henry, VA, was either elevated or dismissed as unreliable.

There's a typo in your title

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And the earliest storm for a season is introduced in 1951. A Jan 2 storm, interesting (most probably subtropical, as the author points out). And with an also introduced Dec storm, that should be the longest hurricane season recorded.

You have to be impressed that FL got hammered by five Cat 4s in six years! That is just insane.

(Total includes the four upgrades + the 1947 "Fort Lauderdale" cyclone.)

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Cat 4 (115 kt) on the Yucatan and Cat 3 (100 kt) near Tampico-- kind of what I had always expected.

How much of a beating? Is it no longer one of the top years?

Falls from 2nd to 5th place. Now having the top 4 being in the current +AMO cycle.

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You have to be impressed that FL got hammered by five Cat 4s in six years! That is just insane.

(Total includes the four upgrades + the 1947 "Fort Lauderdale" cyclone.)

Yeah, crazy. We'll have to watch out for 2060 for the next Florida cyclone flurry.

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Not saying it wasn't a 4, but stacking a bunch of assumptions about wind-pressure relationships on top of each other to eek out 115 is a bit of a disappointment.

Actually, it's a very reasonable conclusion given that RMW, which is insanely small. This aside, the Miami WBO had 106 kt sustained. It wasn't at a standard height, but it was a solid reading. All of this aside, wind damage was very heavy in the core region-- the city got really raked. For years I've thought it might have been a Cat 4, and it seems to me to be a completely logical conclusion.

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Actually, it's a very reasonable conclusion given that RMW, which is insanely small. This aside, the Miami WBO had 106 kt sustained-- it wasn't at a standard height, but it was a solid reading. All of this aside, wind damage was very heavy in the core region-- the city got really raked. For years I've thought it might have been a Cat 4, and it seems to me to be a completely logical conclusion.

I understand the logic of the conclusion, but don't really trust standardized WP relationships...especially when they are massaged for latitude and then massaged another time for RMW. I'm not saying that King was unimpressive, but I just don't see this master's thesis as providing some sort of vindicating "proof" that King was a 4. If it was, it was a very tenuous one at best. We all know how imprecise a tool these standard relationships are, and this one compounds that uncertainty even further.

But then again, I am a master's student in the humanities, so what do I know?

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I understand the logic of the conclusion, but don't really trust standardized WP relationships...especially when they are massaged for latitude and then massaged another time for RMW. I'm not saying that King was unimpressive, but I just don't see this master's thesis as providing some sort of vindicating "proof" that King was a 4. If it was, it was a very tenuous one at best. We all know how imprecise a tool these standard relationships are, and this one compounds that uncertainty even further.

But then again, I am a master's student in the humanities, so what do I know?

You are correct that wind-pressure relationships aren't as standardized as we'd once thought-- and, in fact, his whole conclusion is based on this very fact. Back in the 1980s, a 955-mb 'cane was a Cat 3-- end of story. Now they better understand the other factors involved, and the relevant factors all point to a higher-than-average wind for that pressure: the tiny RMW, the explosive intensification up to landfall (making mixing down to the surface more likely), and the near-tropical latitude. Add to this the evidence on the ground-- a very high wind reading from an official reporting station in the core and heavy damage at the surface-- and I have to ask you what other evidence you need.

Are there other cyclones from the last sixty years that provided better evidence of Cat-4 landfall intensity? If so, I'm not aware of them.

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You are correct that wind-pressure relationships aren't as standardized as we'd once thought-- and, in fact, his whole conclusion is based on this very fact. Back in the 1980s, a 955-mb 'cane was a Cat 3-- end of story. Now they better understand the other factors involved, and the relevant factors all point to a higher-than-average wind for that pressure: the tiny RMW, the explosive intensification up to landfall (making mixing down to the surface more likely), and the near-tropical latitude. Add to this the evidence on the ground-- a very high wind reading from an official reporting station in the core and heavy damage at the surface-- and I have to ask you what other evidence you need.

Are there other cyclones from the last sixty years that provided better evidence of Cat-4 landfall intensity? If so, I'm not aware of them.

What was this very high reading? The non-standard 106kts? Also, wouldn't 955 be close to the highest documented cat4 landfall ever?

I'm open minded and can be persuaded that King was a 4, but this just doesn't quite get me there.

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Yes. It was at a nonstandard elevation, but it was an official reporting station (the Miaimi WBO), it was Downtown (not on the immediate coast), and it was a 1-min average. It's an impressive reading.

Definite evidence of a major, sure.

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What was this very high reading? The non-standard 106kts? Also, wouldn't 955 be close to the highest documented cat4 landfall ever?

I'm open minded and can be persuaded that King was a 4, but this just doesn't quite get me there.

Iris 2001-- another very small cyclone-- generated winds much stronger (125 kt) with a pressure that was just as little lower (948 mb) as it made landfall in BZ. Iris and King are analogous in terms of dimensions, and these wind-pressure combos correlate nicely.

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