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Windspeed

Historical Tropical Cyclones, Reanalysis and Climatology Discussion

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21 hours ago, ncforecaster89 said:

Hi Liberty!  I’ve done a lot of statistical research into NATL basin activity via HURDAT2 and other historical sources.  These records seem to indicate that the recent apparent increase of major hurricanes (MH) during the month of October isn’t that unusual or even anomalous.  

Here’s an overview of the known October MH activity in the NATL basin since 1851.  It’s important to note that it’s highly likely...more like a certainty...that many other MHs are unaccounted for in the historical record prior to the satellite era, beginning in 1966. Moreover, it’s also most probable that a large number of the known hurricanes and major hurricanes likely had a higher peak intensity than presently listed in HURDAT2; especially the further it goes back in time.  With that in mind, I’m also listing all the conservatively estimated 90 kt hurricanes from 1851-1910 and the 95 kt hurricanes from 1911-2000.  The years highlighted in bold correspond to the seasons in which the strongest hurricane of that year occurred in either October or November (48 out of the 168 seasons since 1851). 

1852 = 90 kt; 1853 = 90 kt; 1858 = 90 kt; 1859 = 110 kt; 1860 = 90 kt, 90 kt 1865 = 90 kt; 1866 = 120 kt; 1867 = 110 kt; 1868 = 90 kt, 90 kt; 1869 = 90 kt; 1870 = 100 kt, 90 kt, 90 kt; 1873 = 100 kt; 1874 = 90 kt (NOV); 1875 = 90 kt; 1876 = 90 kt, 100 kt; 1877 = 100 kt; 1878 = 120 kt, 100 kt, 90 kt; 1879 = 90 kt (NOV); 1880 = 120 kt; 1882 = 120 kt; 1884 = 90 kt; 1886 = 105 kt; 1887 = 90 kt; 1888 = 95 kt; 1893 = 105 kt, 115 kt; 1894 = 105 kt, 115 kt, 95 kt; 1895 = 90 kt; 1898 = 115 kt; 1899 = 95 kt; 1902 = 90 kt; 1905 = 105 kt; 1906 = 105 kt; 1908 = 95 kt, 90 kt; 1909 = 105 kt, 90 kt (NOV); 1910 = 130 kt;  1912 = 100 kt (NOV); 1916 = 105 kt, 95 kt; 

1921 = 120 kt; 1922 = 95 kt; 1924 = 145 kt; 1926 = 130 kt; 1932 = 150 kt; 1933 = 110 kt; 1934 = 100 kt (NOV); 1939 = 120 kt;  1941 = 105 kt; 1942 = 95 kt (NOV); 1943 = 95 kt; 1944 = 125 kt; 1947 = 105 kt;  1948 = 110 kt; 1949 = 95 kt; 1950 = 95 kt, 100 kt, 115 kt; 1952 = 125 kt; 1954 = 115 kt; 1955 = 95 kt; 1959 = 105 kt; 1961 = 110 kt, 140 kt; 1962 = 95 kt, 100 kt; 1963 = 125, 95 kt;  1964 = 130 kt, 110 kt; 1966 = 130 kt; 1975 = 120 kt; 1985 = 105 kt (NOV); 1988 = 125 kt; 

1994 = 95 kt (NOV); 1995 = 130 kt, 110 kt; 1996 = 100 kt; 1998 = 155 kt (NOV); 1999 = 95 kt, 135 kt (NOV);  2000 = 120 kt; 2001 = 125 kt, 120 kt (NOV); 2002 = 125 kt; 2003 = 110 kt; 2005 = 160 kt, 100 kt; 2008 = 115 kt, 125 kt (NOV); 2011 = 120 kt, 100 kt; 2012 = 100 kt; 2014 = 125 kt; 2015 = 135 kt; 2016 = 145 kt, 120 kt, 100 kt; 2017 = 100 kt; 2018 = 140 kt.

As can be ascertained from these data, the seemingly increases in late-season/October MH frequency is more the result of much improved detection and verification of such storms, as well as a recency bias.  The biggest takeaway for me is the realization that a very significant number of NATL basin major hurricanes occur after 9/30.        

Very interesting, so there hasn't been some sort of cyclic or pattern change that would cause this! How far back would you say that the HURDAT2 list is reasonably accurate, both on quantity and intensity?

 

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King in 1950 was an interesting one.  Almost a huge tornado.  I experienced the eye almost dead center.  It was completely calm.  People were lighting matches and holding them up and they did not blow out.  In others I've been in there was some air movement in the eye.  The match trick would not have worked.

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On 5/6/2019 at 6:19 PM, LibertyBell said:

Very interesting, so there hasn't been some sort of cyclic or pattern change that would cause this! How far back would you say that the HURDAT2 list is reasonably accurate, both on quantity and intensity?

 

Given that the majority of major hurricanes develop in the western Caribbean, during the month of October, the warm phase of the ENSO cycle is most influential in suppressing such activity...while the cool or neutral phase doesn’t have as profound of an effect.  Moreover, the warm phase of the AMO is a significant driver of increased activity in the NATL basin throughout the season...to include the late season months of October and November.    

The beginning of the satellite era (1966 onward) is the point of delineation for me in determining the period whereby HURDAT2 is most reasonably accurate.  Prior to that time, without satellite surveillance, it is a virtual certainty that many TCs (to include major hurricanes) went undetected, and many others’ intensity was likely underestimated; especially the further we go back in time.  Of course, my definition of what characterizes being “reasonably accurate” might have a higher threshold than others...where some may consider the beginning of Recon flights in 1943, being a more reasonable standard in that regard.    

As you noted previously, more recent records indicate that the mainland USA experiences a category-five hurricane roughly every 30 years, on average.  As such, it’s highly likely that there were additional category-five hurricane landfalls (at least 1 or 2) prior to the 1935 Great Labor Day hurricane...despite HURDAT2 showing no such occurrences for at least the 85 year period from 1851-1935.    

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20 hours ago, ncforecaster89 said:

Given that the majority of major hurricanes develop in the western Caribbean, during the month of October, the warm phase of the ENSO cycle is most influential in suppressing such activity...while the cool or neutral phase doesn’t have as profound of an effect.  Moreover, the warm phase of the AMO is a significant driver of increased activity in the NATL basin throughout the season...to include the late season months of October and November.    

The beginning of the satellite era (1966 onward) is the point of delineation for me in determining the period whereby HURDAT2 is most reasonably accurate.  Prior to that time, without satellite surveillance, it is a virtual certainty that many TCs (to include major hurricanes) went undetected, and many others’ intensity was likely underestimated; especially the further we go back in time.  Of course, my definition of what characterizes being “reasonably accurate” might have a higher threshold than others...where some may consider the beginning of Recon flights in 1943, being a more reasonable standard in that regard.    

As you noted previously, more recent records indicate that the mainland USA experiences a category-five hurricane roughly every 30 years, on average.  As such, it’s highly likely that there were additional category-five hurricane landfalls (at least 1 or 2) prior to the 1935 Great Labor Day hurricane...despite HURDAT2 showing no such occurrences for at least the 85 year period from 1851-1935.    

Thanks, it makes me wonder how many storms and canes we actually had in 1933, the record which was overtaken by 2005.  It's possible that 1933 had more if the records from back then are that incomplete!

 

About the AMO, I wonder if that cycle is of variable length, it seems like the earlier periods of the warm phase were somewhat dissimilar from each other (1950s-1960s), (1990s-2000s), etc.

 

 

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On 5/7/2019 at 9:02 PM, ncforecaster89 said:

Given that the majority of major hurricanes develop in the western Caribbean, during the month of October, the warm phase of the ENSO cycle is most influential in suppressing such activity...while the cool or neutral phase doesn’t have as profound of an effect.  Moreover, the warm phase of the AMO is a significant driver of increased activity in the NATL basin throughout the season...to include the late season months of October and November.    

The beginning of the satellite era (1966 onward) is the point of delineation for me in determining the period whereby HURDAT2 is most reasonably accurate.  Prior to that time, without satellite surveillance, it is a virtual certainty that many TCs (to include major hurricanes) went undetected, and many others’ intensity was likely underestimated; especially the further we go back in time.  Of course, my definition of what characterizes being “reasonably accurate” might have a higher threshold than others...where some may consider the beginning of Recon flights in 1943, being a more reasonable standard in that regard.    

As you noted previously, more recent records indicate that the mainland USA experiences a category-five hurricane roughly every 30 years, on average.  As such, it’s highly likely that there were additional category-five hurricane landfalls (at least 1 or 2) prior to the 1935 Great Labor Day hurricane...despite HURDAT2 showing no such occurrences for at least the 85 year period from 1851-1935.    

 

Well, according to the re-analysis project, there are several Category 4 storms close to Category 5 strength at landfall:

Pre-records: 1846 Hurricane may have been at Cat 5 intensity near Florida Keys.

August 1856 - "Last Island" - 150 mph/934 mb

August 1886 - "Indianola" - 150 mph/925 mb

 

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On 5/9/2019 at 8:03 AM, Floydbuster said:

 

Well, according to the re-analysis project, there are several Category 4 storms close to Category 5 strength at landfall:

Pre-records: 1846 Hurricane may have been at Cat 5 intensity near Florida Keys.

August 1856 - "Last Island" - 150 mph/934 mb

August 1886 - "Indianola" - 150 mph/925 mb

 

You're reading my mind, as those are precisely the top candidates for most likely category-five hurricanes USA landfalls  whose intensity was underestimated.  Those aside, others listed in the early HURDAT2 records could've been underestimated due to lack of data, as well.  The 1846 hurricane is one that has always fascinated me as a probable category five.   

Edit: Just realized the typo for the date of the hurricane referenced in the last sentence (meant the 1846 hurricane; not 1842).  

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