ATL: OTTO - Post-tropical - Discussion

[HURAKAN]

vorticity keeps increasing

[cycloneye]

So far, Puerto Rico has escaped the big rains,but will it last as the tail moves thru? There is the low pressure north of the Virgin Islands.

[cycloneye]

12z Best Track

AL, 97, 2010100512, , BEST, 0, 190N, 653W, 30, 1006, LO

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 010.invest

[wxman57]

When I first looked at the satellite this morning I thought that it appeared less organized than yesterday. What caught my eye was the big upper level low that the squalls are being drawn into just NW of the disturbance. As such, I can see what all the models have been developing - the upper-level low. So my thinking is that development potential may have decreased with the upper low there now.

What really got my attention was the disturbance out in front south of the DR. Upper-level winds look much more favorable there.

[HURAKAN]

Loop

[SouthDadeFish]

I almost see another circulation center south of DR. First visible images suggest another surface center may be forming there. There is clearly inflow streaming in from the west. Am I the only one seeing this? As Wxman said, conditions are more favorable there.

[Cyclone1]

Think we could potentially get two tropical cyclones out of this mess?

[SouthDadeFish]

Think we could potentially get two tropical cyclones out of this mess?

Models have been hinting at that potential for days now. They seemed to split this mess into two systems.

[KWT]

Yeah thats exactly what I see Wxman57, it was why I was a touch surprised they went code red with it, it almost doesn't look tropical at the moment to me.

If it develops IMO its going to be a weak very sheared system.

[jconsor]

Agree that the dry air and strong SSW winds aloft associated with the upper low are disrupting 97L currently. While the upper low will delay development, I'm confident that it won't prevent development. I would give 97L about a 75% chance of development in the next 48 hours. By Thu, 97L should be about 150 miles north of the upper low. Once this occurs the upper low may actually enhance diffluence over 97L.

I do expect only slow strengthening because 97L is a large system with some subtropical characteristics, and the global model guidance indicates the strongest core of winds rather far out from the center - about 100-150 miles. GFDL/HWRF treat this as a purely tropical system and for that reason are intensifying it too quickly.

Also agree that the convection south of Hispaniola needs to be watched carefully. There is broad rotation based on vis loops. This system is associated with a tail of vorticity extending SW from 97L that will likely persist for at least the next week in the central and western Caribbean once 97L moves out.

When I first looked at the satellite this morning I thought that it appeared less organized than yesterday. What caught my eye was the big upper level low that the squalls are being drawn into just NW of the disturbance. As such, I can see what all the models have been developing - the upper-level low. So my thinking is that development potential may have decreased with the upper low there now.

What really got my attention was the disturbance out in front south of the DR. Upper-level winds look much more favorable there.

[KWT]

Its the sort of system thats like Bonnie which also looked a mess, if it does get 24hrs of somewhat lower shear at any point it'll probably have enough going for it to quickly develop into a weak sheared system so I'd say 60% is a decenr chance despite how poor it currently looks.

[cycloneye]

Low center very exposed.

[HURAKAN]

Doesn't appear to be center in loops Luis. Appears to be a vortex or something. It's rotating around the broad center.

[Sanibel]

The ULL is what was giving the west wind look to the convection two days ago. A ULL right into the system is a non-starter.

The convection south of Hispaniola is just shear-induced even though it looks like a Low center (for now anyway) Potential tracks from this are more interesting:

[chrisjslucia]

[quote="cycloneye"]So far, Puerto Rico has escaped the big rains,but will it last as the tail moves thru?

Heavy at times torrential rain in St Lucia being blown in on gusting winds from the South East / South - this is shown to be past us on the visible sat images but there is certainly a sting in the tail of this system at present.

[expat2carib]

Heavy at times torrential rain in St Lucia being blown in on gusting winds from the South East / South - this is shown to be past us on the visible sat images but there is certainly a sting in the tail of this system at present.

Hi Chris. I'm in Rodney Bay at this moment. The rain is falling but it's only a small piece of popcorn on the radar as can be observed here. I think it will be over in half an hour.

http://www.meteo.fr/temps/domtom/antilles/pack-public/animation/animMOSAIC2.html

[KWT]

Yeah there is alot of convection tailing into the NE Caribbean, not all that surprising given the shear aloft at the moment making for quite a favourable set-up for plenty of convection to brew.

[HURAKAN]

Loop - http://rammb.cira.colostate.edu/ramsdis ... is_floater

Broad center around 21N and 66W

[KWT]

The problem is its pretty much sitting close to the ULL, indeed wouldn't shock me to see the NHC start to mention the chance of a subtropical system.

[dwsqos2]

Keep in mind that there seems to be an almost de facto tendency by the NHC to call anything in which the genesis involves a tropical wave a tropical rather than subtropical cyclone. Look at Harvey 2005, Hanna 2002, and Juan 2003. All of these became more tropical, but look at satellite images during the early stages of Harvey in particular to see how involved with an ULL it was.

I can see the ULLs proximity to the circulation but just pointing that out.