Frequency of Hurricane Formation (climo)

This is the general tropical discussion area. Anyone can take their shot at predicting a storms path.

Moderator: S2k Moderators

Forum rules

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

Help Support Storm2K
Message
Author
User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Frequency of Hurricane Formation (climo)

#1 Postby Spacecoast » Mon Aug 22, 2022 1:54 pm

I was curious about how often hurricanes form.
So....
Image


It looks like, (on average), CAT1+ hurricanes form ~every 14 days (blue linear) trending down slightly since 1950 (n=466).
The red line is a 5 storm moving average, which occasionally dips below 10

The max number is 104 for year 1982 between Alberto (6/3/1982), and Debbie (9/15/1982).

There have been five cases of Hurricanes forming on the same day:
2017: Jose & Katia (9/6/2017)
2012: Leslie & Micheal (9/5/2012)
2010: Shary & Tomas (10/30/2010)
1995: Humberto & Iris (8/23/1995)
1993: Gert & Harvey (9/20/1993)
And on 9/8/1980 three Hurricanes formed: - Earl & Frances & Georges.

Anyway I was trying to figure out how likely it is for 9 Hurricanes to form in the next 60 days.
9 Hurricanes - 1 every 6.5 days throughout Sept and Oct. ....idk, I think this amount of backloading is very rare
8 Hurricanes - 1 every 7.5 days throughout Sept and Oct
7 Hurricanes - 1 every 8.5 days throughout Sept and Oct

The data above includes August and November (the entire season), which probably skews the averages higher.
I will try to breakout frequencies by month specifically for Sept, and Oct.
8 likes   

User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Re: Frequency of Hurricane Formation (climo)

#2 Postby Spacecoast » Tue Aug 23, 2022 11:11 am

"Anyway I was trying to figure out how likely it is for 9 Hurricanes to form in the next 60 days. "

1950-2021 data from HURRDAT:
Upon further analysis, it appears that 9 (even 10) H's forming after Sept 1st is not unprecedented, but still uncommon...
Image

Average number of H's (blue) after Sept 1st is four to five.
Min # is 1, Max # is 10.

2005, & 2020 had ten H's after 9/1
1969, 2001, & 2010 had nine H's after 9/1
1999 had eight
1961 had seven

Of course, past performance is not an indicator of future activity, as each season is unique.
I leave the predictions to experts, who forecast 7-9 hurricanes, which is certainly still possible / likely.

On a side note, it's been 333 days since the last Hurricane (Sam) formed on 9/24/2021. That may be some kind of record.
5 likes   

User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Re: Frequency of Hurricane Formation (climo)

#3 Postby Spacecoast » Tue Aug 23, 2022 5:20 pm

Spacecoast wrote:
On a side note, it's been 333 days since the last Hurricane (Sam) formed on 9/24/2021. That may be some kind of record.


btw, 333 days without 'cane formation is not a new record (it is in the top 5 inter-seasonal stretches, though).

As far as I can tell, (1950-2021), the record is:

365 days between
Chantal, (which formed on 9/11/1983), and Diana, which formed(9/10/1984).
2 likes   

User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Re: Frequency of Hurricane Formation (climo)

#4 Postby Spacecoast » Tue Sep 13, 2022 2:41 pm

Post peak update (1950-2021 data from HURRDAT):

In a typical year (7.2 hurricane season), 4 hurricanes would had already formed by Sept 11th

Updating the graph to show number of 'canes formed after Sept 11th.....
Image
Average number of H's (blue) after Sept 11th is three (trending up from two to four).
Min # is 0, Max # is 9.
2010 & 2020 had nine H's after 9/11
2001 & 2005 had eight.

Again, past performance is not an indicator of future activity.
I'm not sure any (reliable) indicator of future activity exists.
5 likes   

User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Re: Frequency of Hurricane Formation (climo)

#5 Postby Spacecoast » Sun Oct 09, 2022 11:43 am

Updated numbers for rest of season....
Image
After Oct 1st:
Average number of 'canes = 1.6
Minvalue = 0. Maxvalue = 6 (in 2020)
16 years (22.2%) had zero hurricanes after Oct 1st.

Image
After Oct 15th:
Average number of 'canes = 1.0
Minvalue = 0. Maxvalue = 4 (in 2020)
27 years (37.5%) had zero hurricanes after Oct 15th.

Image
After Nov 1st:
Average number of 'canes = 0.44
Minvalue = 0. Maxvalue = 3 (in 2001)
48 years (66.7%) had zero hurricanes after Nov 1st.
Last edited by Spacecoast on Sun Oct 09, 2022 12:20 pm, edited 2 times in total.
3 likes   

User avatar
Teban54
Category 5
Category 5
Posts: 1903
Joined: Sat May 19, 2018 1:19 pm

Re: Frequency of Hurricane Formation (climo)

#6 Postby Teban54 » Sun Oct 09, 2022 11:59 am

Spacecoast wrote:Updated numbers for rest of season....
https://i.ibb.co/44T923W/numa.jpg
After Oct 1st:
Average number of 'canes = 1.6
Minvalue = 0. Maxvalue = 6 (in 2021)
16 years (22.2%) had zero hurricanes after Oct 1st.

https://i.ibb.co/CvhQ3Nq/numb.jpg
After Oct 15th:
Average number of 'canes = 1.0
Minvalue = 0. Maxvalue = 4 (in 2021)
27 years (37.5%) had zero hurricanes after Oct 15th.

https://i.ibb.co/cvGRDHR/numc.jpg
After Nov 1st:
Average number of 'canes = 0.44
Minvalue = 0. Maxvalue = 3 (in 2002)
48 years (66.7%) had zero hurricanes after Nov 1st.

By "2021", you mean 2020 right? :lol:
2 likes   

User avatar
Spacecoast
Category 2
Category 2
Posts: 687
Joined: Thu Aug 31, 2017 2:03 pm

Re: Frequency of Hurricane Formation (climo)

#7 Postby Spacecoast » Mon Nov 21, 2022 3:02 pm

Last update to this thread...
Although the official end of season is 11/30, Hurricanes forming in Dec / Jan are not unprecedented.

Image
After Nov 15th:
Average number of 'canes = 0.21
Minvalue = 0. Maxvalue = 2 (1962)
58 years (80.6%) had zero hurricanes after Nov 15th.

Image
After Dec 1st:
Average number of 'canes = 0.07
Minvalue = 0. Maxvalue = 1
67 years (93.1%) had zero hurricanes after Dec 1st.

(HURRDAT2 lists 'Alice' forming on Dec 31st, 1954. This seems to be the latest calendar hurricane over last 72 years, (not sure why it was named as an 'A' storm, as there was another Alice named earlier as the 1st storm of 1954). Apparently after 11/30, they start the new season.

A case can be made that the season doesn't really end until mid January.
'Alex' formed 1/14/2016, making it the earliest calendar hurricane over last 72 years, but could be considered last storm of the 2015 season.
1 likes   

User avatar
1900hurricane
Category 5
Category 5
Posts: 6044
Age: 32
Joined: Fri Feb 06, 2015 12:04 pm
Location: Houston, TX
Contact:

Re: Frequency of Hurricane Formation (climo)

#8 Postby 1900hurricane » Wed Nov 23, 2022 12:21 am

Spacecoast wrote:Last update to this thread...
Although the official end of season is 11/30, Hurricanes forming in Dec / Jan are not unprecedented.

https://i.ibb.co/zx6G31m/huuraJPG.jpg
After Nov 15th:
Average number of 'canes = 0.21
Minvalue = 0. Maxvalue = 2 (1962)
58 years (80.6%) had zero hurricanes after Nov 15th.

https://i.ibb.co/55fTMSs/huurb.jpg
After Dec 1st:
Average number of 'canes = 0.07
Minvalue = 0. Maxvalue = 1
67 years (93.1%) had zero hurricanes after Dec 1st.

(HURRDAT2 lists 'Alice' forming on Dec 31st, 1954. This seems to be the latest calendar hurricane over last 72 years, (not sure why it was named as an 'A' storm, as there was another Alice named earlier as the 1st storm of 1954). Apparently after 11/30, they start the new season.

A case can be made that the season doesn't really end until mid January.
'Alex' formed 1/14/2016, making it the earliest calendar hurricane over last 72 years, but could be considered last storm of the 2015 season.

Alice wasn't designated operationally until after the calendar changed years. Post storm analysis found it developed earlier however, so the analyzed point of development went forward and crossed the calendar year.
0 likes   
Contract Meteorologist. TAMU & MSST. Fiercely authentic, one of a kind. We are all given free will, so choose a life meant to be lived. We are the Masters of our own Stories.
Opinions expressed are mine alone.

Follow me on Twitter at @1900hurricane : Read blogs at https://1900hurricane.wordpress.com/


Return to “Talkin' Tropics”

Who is online

Users browsing this forum: Blown Away, duilaslol, Google [Bot] and 31 guests