Shell Mound wrote:Ubuntwo wrote:Shell Mound wrote:One thing is clear: models do not suggest that conditions will become especially conducive in the Atlantic until mid-July or later. Even during the first half of July, despite the onset of the CCKW, the global models still show a rather persistent TUTT over/near the Greater Antilles. This would shear apart anything that manages to develop, regardless of SAL/sinking air. Already this is a sharp difference between 2020 and 1933/2005. During the latter two hyperactive seasons, the Atlantic mustered Cat-2+ hurricanes as early as the first week of July. So we can already safely rule out that this season will be like 1933/2005, even in terms of overall ACE rather than numbers. On the other hand, borderline or lower-end “hyperactive” seasons such as 1996 and 2017 are still in play, although I’d lean more toward the former than the latter at this stage, given the possibility of strong trade winds due to enhanced ridging and retrograding TUTTs during peak season.
While I agree that this season will fall far short of 2005 and 1933, I don't think the semi-continuous presence of a TUTT on modeling is something to extrapolate an entire season's activity off of.
Well, a persistent TUTT not only signifies increased vertical wind shear and (typically) sinking air, but also creates more weaknesses allowing storms to curve OTS. Historically, most (~75% of) major hurricanes to hit the U.S. first developed in the MDR, so if the MDR is juxtaposed with stronger shear, more sinking air, and more weaknesses in the ridging, the chances of a major hurricane hitting the U.S. are considerably lower than otherwise. It is time to watch for the recurrence of these features and their locations in real time, besides trends on models. So far 2020 has been seeing a fair amount of development in the subtropics, but with no sign as yet of the MDR becoming notably more conducive, at least through mid-July, while available evidence suggests that the next named storm is most likely to develop off the Carolinas and/or Mid-Atlantic during early July. The GFS is most probably seeing yet another convectively generated ITCZ “ghost” in the MDR, given the tiny size of the vortex on the latest run(s). The EC/EPS and other dynamical models are far less aggressive.
I think you base your claims too much on short-term trends and not enough on long-term trends. The CFS shear forecasts are subject to frequent fluctuations. It's not a surprise we haven't had any MDR development yet - it's June 25th! Regardless, the environment for MDR TCG may be more conducive than normal in July, with above normal SSTs, a favorable base state, and strong rising motion over Africa/The IO.
Today's 12z has a further increase in MDR activity, as well as reduced support for the subtropical Atlantic development.
