It’s getting pretty obvious that Mother Nature got exhausted and decided to turn off the tropics at the beginning of October. It’s not clear exactly what factor or factors caused the tropical-system generator to switch off – it was probably a combination of things. But the upper-level wind pattern over Florida, the Gulf, and the surrounding area has taken on a wintertime configuration, and shows no sign of becoming less hostile to tropical development.
But far to the north, the National Hurricane Center is now highlighting an area off the Northeast coast as a possible tropical-development zone. In a day or two, a non-tropical system and its connected cold front will move off the Northeast U.S. coast and combine with another storm coming from the south. This unusual combo storm is forecast to produce dangerous wind and flooding in the Northeast and southern New England Tuesday into Wednesday.
There is a decent chance that a low-pressure center associated with that merged system could become somewhat tropical while it tracks over the warmish Gulf Stream waters mid to late week.
The winds will be quite strong with the new combo system, so it will likely be called Wanda if the NHC determines it to be sufficiently tropical in nature to get a name. In any case, it will move out to sea.
Meanwhile, the weather pattern over the southern Caribbean is forecast to remain conducive for tropical development for the next couple weeks. Although, the long-range computer forecast models show the odds of development, even there, are very low.
The large-scale atmospheric feature called the MJO is almost certainly at least partially responsible for the big tropical shutdown. The MJO is a wave-like phenomenon that alternately makes the tropical atmosphere over the Atlantic more and less conducive for systems to develop. It has been stuck in a hostile phase for most of October, though computer forecast models predict the MJO will move into a more supportive phase late this month into early November.
The MJO factor can become conducive for development while the weather pattern stays hostile, however. Other factors, including the normal seasonal change, can override a supportive large-scale environment.
The bottom line is, it’s still possible for a tropical system to develop in the Caribbean. At this point, it doesn’t appear likely, however. And it’s even less likely that a system would affect Florida.
Still, until the wintertime weather regime settles far enough south to exclude development in the southern Gulf or the Caribbean, we’ll have to glance that way now and then to be sure there are no surprises.