Teban54 wrote:Since the 2017 comparison has come up a lot in the discussions, I went back and quoted some (season cancel or borderline season cancel) comments from the
2017 indicators thread, between August 1 and August 30 when Irma formed.
Scroll down to August 16 if you want a shorter read; the peak season canceling occurred on August 19. (More stuff could be found by just extending the time frame to July 30, but I chose not to.)
Impressions:
[*] SAL also ended up being a significant issue for August 2017, but
a few posters thought the SAL outbreaks could have been caused by the strong waves themselves. Specifically, it was also
mentioned that
waves were too far north.
I have wondered even then if there's something to this even then, there seems to (especially with more sample sizes) be a correlation between early MDR formation and the ITCZ being much farther north than normal--and the end result of this also leading to a significant lull or absence of activity until the end of August followed by more significant activity
1979 had Ana in June, two more storms in the first half of July, and then a depression in late July--and then literally
nothing until August 25--after that four storms developed in the following ten days (though activity was cut short early that year by El Nino's quick onset, similarly to 2006)
1996 had Bertha in early July, early season major hurricane similar to Beryl, followed by Cesar in late July--then we had, again, literally nothing between July 28 and Aug 19, after which four storms formed in a week (though 1996 featured an unusual lull between Hortense and Isidore)
2000 had TD2 out in the far eastern Atlantic in late June, absolutely nothing in July, and then, Alberto aside (lasting 22 days) had a very underperforming August: Beryl was forecast to be a hurricane and only reached 50mph, Chris lasted a day despite a near hurricane intensity forecast, and Debby's infamous forecasting bust, and then from Aug 24 to Sep 10, only one short-lived storm formed--then we had seven storms from Sep 11-Oct 5 (and even more after)
2005 had Dennis and Emily before July 10, and despite storms forming during August, still drastically underperformed--Irene struggled to maintain tropical storm intensity for days (even being flung north of 20N pretty far to the east) and only short-lived systems after that, up until Aug 22 when Katrina formed
2010 had a system in June that was arguably a tropical depression so I'm going to count it here for the sake of data completion--we had a (near) major hurricane in June, and then two weak tropical storms in late July/early August, followed by, again, nothing--and then once Danielle formed on Aug 21, we had six storms in the next two weeks (and the season remained active throughout--but it is worth noting 2010 had the strongest La Nina of this sample
2017 had Bret and TD4 in the MDR before July 4 and, as the quoted post turns out, the MDR drastically underperformed until pretty much the end of August
2018 had Beryl (as a hurricane) in the first few days of July out in the MDR, and then after Chris a few days later, the Atlantic was completely dead, save for to cutoff-low induced storms in early August--then things woke up at the start of September
2022, now infamous for having nothing during August and most of July, had Bonnie--despite not developing until the Caribbean, it formed from a well developed late June wave, before things took off in September (Bonnie's struggles did herald the difficulties most MDR storms would have that year)
2023 had not one, but two MDR storms (one of which was almost a hurricane), one hurricane in July (in the subtropics) but otherwise nothing after that, and then the switch flipped and then some around August 20
The two years that stand out are 2008, which had generally consistent development through the season (save for the two weeks in early to mid September) having generally no more than ten days pass between development, and 2021, a year that had a significant quantity over quality nature and largely constant development during August and September, given the vast majority of storms that year (with some very obvious exceptions) struggled or underperformed, and the season cut off after September for still unclear reasons
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