Category5Kaiju wrote:https://twitter.com/philklotzbach/status/1448711837562781697
This is something you don't see every year. Given it is October, I would be very surprised if no major, potent cyclone in any basin worldwide forms during this month; that would be beyond mind-boggling. My guess is given the La Nina state and above average sst anomalies in the western part of the basin the Atlantic would have a very good chance to produce something significant even if it is by the month's end, and of course the WPAC is able to crank up super typhoons even during La Nina years (Zeb, Goni, Megi, etc.). But it is strange to see how all three major NH basins this year have been very MJO-dependent as hammy explained; I am guessing the amplitude has something to do with it, but why it has had a greater amplitude this year than others I do not know.
Interestingly, both years (1985 & 2010) were both LaNina years. 2010 was a strong LaNina and obviously a busy year (19/12/5) but October storms quickly succumbed to increasing wind shear by the time reaching 20N. 1985 was a 2nd yr. LaNina with average numbers (11/7/3) where activity seemed to tail off after Gloria for most of October, until Juan landfalled as a min. hurricane in Louisiana and major hurricane Kate formed in mid November and landfalled N. Florida as a Cat 2. Meanwhile, 2021 has been a very busy year thus far during a year ballyhoo'd as a developing cool neutral ENSO leading toward LaNina yet upper level conditions during October have evolved to anything but LaNina-like. I too would have bet my last quarter that October would have been gang-buster in light of the warm SST's and favorable upper level conditions that with a late year transitioning LaNina. I'll say this though, I've always found there to be roughly a 30 day lag following a newly transitioning ENSO pattern change prior to impacting Atlantic tropical cyclone activity.
One part of me looks at present and near term forecast conditions realizing that it's already Oct 15. and minimal hints that tropical activity will suddenly "pop" anytime soon. The much anticipated MJO factor to ignite W. Atlantic basin tropical activity has seemed to continue to get pushed back in time, and now appearing to be forecast to have far less amplitude then previously though. Could this be a year where October was largely transitional, but where LaNina conditions will actually kick in starting the last few days of the month and into November?? I think the latter could be a reasonable possibility but only to a degree. November may well bring another major to Central American, Bay of Campeche, or perhaps the N. Caribbean but as things stand now (along with Climo) that risk-window for the CONUS is clearly narrowing.
