Loc: Austin, Tx
Re: 92L Lounge
Fri Aug 18 2017 12:47 AM
Going to go deep into "Lounge talk" on 92L here. Take all of this with a few thousand pound grains of salt. We are still a long way off from potential US impacts from 92L.
It appears likely that 92L may already be a small tropical cyclone tonight, or at the very least, right on the cusp. The operative word is small, and this could have big implications going forward.
As discussed on Weather Underground's WUTV (Weather Channel), a possible shear monster lies in wait for 92L ahead, not to mention, robust pockets of dry air. However, models in aggregate suggest that 92L will travel within enough of a protective envelope to fend off the worst of it.. which would be more believable if 92L wasn't a small cyclone.
The track ahead for 92L into the Bahamas assumes that the system will weaken, at least some, and perhaps to the point of dissipation (though by no means the most likely scenario), or stay weak. This is potentially more unsettling than not. A tenacious system such as 92L has been, to then become a small TC, weaken - or even devolve back to an open wave, but doing so much closer to Florida - is never a good thing.
Over the next 48 hours, there is a window for 92L to not only gain size, but also intensity, and with any luck it may begin to feel the pull of the ULL to its northwest and gain enough latitude that it has a chance to recurve. (IMHO, the odds of this are under 15%, but far from zero).
However, other more likely scenarios are very troubling:
- Small TC with potential for rapid changes in intensity is kept or made weak enough that it in fact tracks into or near the Bahamas, but primarily not over land, and poses a real risk to Florida and possibly the Gulf states later next week (IMHO, 35% odds).
- Becomes larger in size and resists rapid weakening, but never strong enough to recurve. A mid-size strong tropical storm or hurricane, strengthening, as it rakes the Greater Antilles or nearly does so, and possibly still on its way to Florida and/or the Gulf (IMHO 25% odds)
Other scenarios exist and have some model, or at least ensemble member support, but as my own personal opinion goes, the rest all share what is left of the remaining 25% of the pie, and at this time do not seem plausible enough to give lounge time to. One of those of course is complete dissipation.. which is indeed supported by some models' runs.
Here's a breakdown of the Aug 18th 0z runs, so far
(You may have read elsewhere why I am giving CMC more attention this year for systems that have good TC DNA)
Sends a deepening and mid-size hurricane across the Bahamas and then has it perform a Fujiwhara loop and then runs up the eastern seaboard, induced by the passing of a well-developed mid-size hurricane (93L) to its northeast... This assumes a lot. Maybe too much. While very plausible that 92L becomes a deepening and larger tropical cyclone over the Bahamas around the 25th of August, it is far from clear if (93L?) will even develop nearly that much, let alone at all.
Poorly initialized. This 'new and improved' GFS has, imho, been less than stellar this season. The 18 0z run fails to even recognize that 92L is now very possibly a tropical cyclone, or will soon be. Keeps 92L as a weak wave and washes it out entirely before whatever is left of it crosses Florida as an afternoon shower. - I would call this a FAIL run.
More analysis of the models' analysis to come..
GFS Ensemble Members
There is zero model support from even a single GFS ensemble member for anything more than 92L becoming a TD at this point. ALL wash it out in the face of dry air and shear. Again, it does appear that there is a bias for poor initialization, but even among members who handle 92L's current state better - 100% wash it out.
Euro, like the GFS, never really develops 92L at all, and also washes it out into a passing rain shower over Florida later next week. So, being that GFS and Euro are in lockstep on this solution, maybe there really is something to that. On the other hand, they were both very muted on 91L until recon flew in. Now the Euro has 91L (Harvey) heading to Tx as a seriously deepening Hur.
Suggests 92L may try to redevelop in the northern Gulf
More model analysis to come...
After briefly allowing for 92L to be a strong TD or low-end storm over the course of the past twelve hours (good initialization), the HWRF then weakens it and primarily keeps it as a very sloppy TD, or open wave, though frisky at times, up until the Bahamas. Only over the Bahamas does it start to slowly reorganize - perhaps a low-end TS upon hitting the Straits of Florida.
HMON (GFDL's replacement)
Like HWRF, allows for 92L to have been a TD/TS for the past twelve hours or so, and like the HWRF, then weakens it - but generally even more so, and never brings it back. Open wave, then death.
The Navy initializes 92L as a sloppy wave at best, and sends most of the wave, or its remnants, to Florida for a shower or two. Apparently a piece of 92L breaks away to merge with (93L?) and cranks that up (mostly 93L at that point) well offshore of Florida.
Initializes and keeps 92L as an open wave. Crosses Florida by late next week as a very weak wave, but suggests development is possible in the Gulf.
In summary, not a lot of model support for 92L to develop at all from the 18/0z runs. What is consistent, is a path towards Florida, which is why, given the wave's DNA, means it must continue to be watched. Should 92L find itself, even briefly, in a favorable environment if and once closer to the state, it could quickly organize (or further ramp up - depending on its state) and pose a threat.
Edited by cieldumort (Fri Aug 18 2017 10:51 AM)