ATL: Ex INVEST 92L - Discussion

[Steve]

Agreed. I wonder if the piece just SE merges or just stays south and hits South America. It could be just ITCZ flare up, but maybe not.

I could be wrong but mimic looks like the next beast swirl looks to come off Africa on a more wnw trajectory. Hopefully that takes it out. We might need a break for a couple weeks.

[Agua]

Yeah, it's got my attention, too. If for no other reason it's that time of year, it's vigorous and it's low.

[Orlando]

Yup! This one might be trouble. My arthritis is already starting to act up a little. I don't think that I had much pain with Hermine. I don't know anything about weather forecasting like the mets do, but sometimes my spidey senses kick in.

[wxmann_91]

Caribbean LLJ will continue to be screaming in the coming days. Which means weak low-level convergence, similar to Hermine and Earl when they were Invests. This won't have a chance to develop until it hits the western Caribbean, if it survives to that point.

[centuryv58]

Well I see we have two completely opposing opinions on the future of this Invest. Now just need to wait to see what it will actually do.

[chaser1]

So, here's my thoughts on 92L and shot at how I perceive the following 5 days will play out. In short, I think 92L will develop at least reaching Tropical Storm strength probably between the Eastern and Central Caribbean

I hate siding with the Canadian model especially when its out there in right field all by itself . But frankly 92L is looking fairly good on satellite. I see the area as moistening up and clearly having weak rotation at some level. It is presently moving pretty quickly but I think it will slow down as it approaches the islands. We are at the climatological peak of hurricane season and there appears to be a lessening chance of 92L will try to develop in the manner that Hermine's island hopping excursion through the islands hampered her. So, given 92L's lower latitude, I think it has the makings of our next tropical cyclone in 3 or 4 days. It is moving fast which might be a near term hindering factor AND looks to be approaching an upper trough about to cut off while also moving generally westward (or southwestward). Its this upper feature that is presently helping fan 92L's outflow through the added upper air diffluence. This same feature might also be responsible for a day of strong shear as 92L catches up to it, thus making 92L look worse in the near future and until 92L can move past it and closer to the islands. What I found interesting is that since 12Z Aug. 30, 5 runs (12 hourly) of the Canadian has insisted on some level of development. During the same period of time, none of the 11 (6 hourly) runs of the GFS have developed 92L. One obvious distinction???? If one were to look back at each of those GFS runs, you'll see that all of them dragged 92L right over those of you in the N. Leewards, Puerto Rico, and every piece of land between itself and Arizona. Meanwhile, a number of the Canadian runs did take 92L further south and into the Caribbean where its present position and southern latitude implies it may well go. So, based on present appearance, overall upper air dynamics, warm SST's, but most of all climatology... I don't see the pockets of dry air lurking not to far away to be enough of a hinderance to keep 92L from developing as it enters or within the Caribbean. Right now the upper level winds throughout the Caribbean are not conducive, however as 92L approach the islands it would appear to be moving under increasingly anticyclonic conditions which would expand over itself with an adequate degree of convection. Further downstream at about 90 hours from now, 92L "supposedly" a T.D. or stronger, would appear to be due south of a stalled Hermine off the Carolina Outer Banks, but with an elongated and stout 594 mid level ridge displaced between them. It is this point (at approx. 90-120 hr.'s) that upper air conditions would seem to be most conducive for eventual stronger development to possibly occur

Thanks for that nice post Chaser1 . So do you think that this has the potential to be a DT by approaching or (and) crossing the Lesser Antilles?

Hi Gusty! Yes, I absolutely think 92L has the potential to be a T.D. while moving through the Northern Windwards and Southern Leewards. That's not to say I'm overly confident that this will happen, but that this system has enough working in its favor and easily has the time to spin up by the time it reaches your longitude. Also, I had erred in my earlier thoughts regarding what I thought looked like the beginning of a small cut off developing just to 92L's west. This seems to simply be a small shear axis moving westward in tandem with 92L, but no longer appears as an upper cut off low. The rub here is this small feature would seem even less likely to act as a near term deterrent toward 92L's development.

[abajan]

[GCANE]

Interesting this has an anticyclone over it.
Its beginning to interact with the ULL and shear is inducing short-duration convection on the NW side of the anticyclone.

[abajan]

Seems like it has decelerated a bit, but that could just be an optical illusion due to where the convection is forming.

[GCANE]

Latest low-level wind analysis

[Blinhart]

I can see them putting this as a TD soon.

[cycloneye]

Up to 20%-30%

Shower and thunderstorm activity associated with a tropical wave
located about 600 miles east of the Lesser Antilles has increased
since yesterday. However, environmental conditions are only
marginally conducive, and any development of this system should
be slow to occur while it moves westward at 15 to 20 mph. This
disturbance is expected to bring locally heavy rainfall and gusty
winds to portions of the Lesser Antilles beginning later today
through Sunday night.
* Formation chance through 48 hours...low...20 percent
* Formation chance through 5 days...low...30 percent

[abajan]

Unsure about the location of the center of circulation and pressure:

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
635 AM EDT SAT SEP 3 2016

... A tropical wave is moving across the central Atlantic with axis
extending from 20N48W to a 1009 mb low near 14N47W to 07N49W,
moving west at 15-20 kt. This wave is embedded in a moderately
moist environment with upper-level diffluence supporting scattered
moderate convection from 13N-18N between 45W-56W. This wave is
also generating a broad area of fresh to strong easterly winds
across the northern portion of it. ...

That differs quite a bit from the info shown in the graphic issued at 2:00 AM EDT and posted by GCANE, where the location is near 13N 49W and the MSLP (mean sea level pressure) is 1004.2 hPa. (According to my info, hPa [hectopascals] are equivalent to millibars.)

Latest low-level wind analysis

http://imageshack.com/a/img924/1870/yAGtw5.gif

[Gustywind]

Seems like it has decelerated a bit, but that could just be an optical illusion due to where the convection is forming.

With untrained eyes seems to have decelarate and expanding convection continues to build quickly everywhere. That's a good sign for 92L, we should monitor it islanders.

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
635 AM EDT SAT SEP 3 2016


A tropical wave is moving across the central Atlantic with axis
extending from 20N48W to a 1009 mb low near 14N47W to 07N49W,
moving west at 15-20 kt. This wave is embedded in a moderately
moist environment with upper-level diffluence supporting scattered
moderate convection from 13N-18N between 45W-56W. This wave is
also generating a broad area of fresh to strong easterly winds
across the northern portion of it.

[cycloneye]

12z Best track:

Location: 13.7°N 51.1°W
Maximum Winds: 25 kt Gusts: N/A
Minimum Central Pressure: 1009 mb
Environmental Pressure: 1011 mb
Radius of Circulation: 140 NM
Radius of Maximum Wind: 90 NM

[AutoPenalti]

It gained 7/10's of a degree north of where it was this time yesterday.

[Gustywind]

When is sheduled the Recon plan?

[ouragans]

Recon postponed to Monday

POSSIBLE LOW LEVEL INVEST AT 05/2000Z NEAR 15.5N 68.5W

[cycloneye]

Tentative mission for September 5 at 4 PM EDT.

POSSIBLE LOW LEVEL INVEST AT 05/2000Z NEAR 15.5N 68.5W