ATL: FOUR - Remnants - Discussion

[tropicwatch]

There appears to be some type of weak circulation still. Do any other models besides the UKMET regenerate this system down the road?

[GCANE]

Latest ASCAT still has a few west wind barbs.
AMSU analysis does not - showing a wave.
IR shows a strong cyclonic circulation.

Looks like vort column is holding up well from just above the boundary layer to about 500mb.

Nothing pushing down on this from the upper troposphere.
200mb PV is well in the clear.

Looks like it is staying well enought below the ULL Shredder at 25N 57W

Anything that will reduce the Convection Inhibitation could set this off.
A nice mid-level moisture feed from the south is currently situated just before the islands.
Need to see what happens then.

[wxman57]

Latest ASCAT is from 12 hours ago - can't use that to judge whether it has an LLC. IR isn't very useful for finding an LLC in such a weak system, though I don't see any circulation in the IR loop. I think that the NHC may well declare it post-tropical in their next advisory.

[GCANE]

This looks like a nearly straight shot west to the islands.

http://tropic.ssec.wisc.edu/real-time/m ... anim=html5

[OuterBanker]

It's amazing how many storms are predicted to hit Jacksonville. Yet, it rarely gets hit.

[GCANE]

Latest ASCAT is from 12 hours ago - can't use that to judge whether it has an LLC. IR isn't very useful for finding an LLC in such a weak system, though I don't see any circulation in the IR loop. I think that the NHC may well declare it post-tropical in their next advisory.

I am watching for any high helicity hot towers.
Premiss is that the helicity would help to transfer the mid vort down to the surface.

[wxman57]

Here's a GOES-16 shot of the system. Convection is dropping off. I can see a weak swirl, but this would not qualify for an upgrade to a TD.

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=18223&y=7766&z=4&im=12&ts=1&st=0&et=0&speed=210&motion=loop&map=1&lat=1&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=20170707094538&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

[Aric Dunn]

the interesting thing is that the CMC has been showing this exact thing is happening with a separate vorticity developing to its north and they eventually merge after interacting. all the while keeping the system alive.

[toad strangler]

These are just singular model runs. Not predictions!

[weathaguyry]

Still a TD!!!

[cycloneye]

Tropical Depression Four Discussion Number 7
NWS National Hurricane Center Miami FL AL042017
1100 AM AST Fri Jul 07 2017

The depression consists of a possible circulation center embedded
within a very small area of intermittent convection. The areal
coverage of the convection has been gradually decreasing since
yesterday, and the cloud pattern is not showing much organization
at this time. NHC is keeping an initial intensity of 25 kt, and
these winds are only occurring in a few remaining squalls.

Although the shear is currently low, the depression is moving into
a relatively low-moisture environment, and this factor in
combination with the fast motion of the cyclone will probably
result in weakening. The depression is forecast to become a remnant
low or degenerate into a open wave tonight.

The depression or its remnants will continue to move toward the
west-northwest at about 18 kt embedded within the strong July
trade winds. This is the solution of the few models which
maintain a distinct perturbation in the flow for a few more days.


FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 15.6N 50.9W 25 KT 30 MPH
12H 08/0000Z 16.5N 53.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 08/1200Z 17.8N 57.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 09/0000Z 19.2N 60.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 09/1200Z 21.0N 63.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 10/1200Z 23.5N 69.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 11/1200Z...DISSIPATED

$$
Forecaster Avila

[wxman57]

Still a TD!!!

In name only. Lix decided not to kill it off now but to wait until the afternoon advisory. Bones is calling it, for now, though Nurse Chapel is continuing the chest compressions...

[Aric Dunn]

there is definately still a closed circ. weak but its quite visible now on the east side of the dying convection.

[GCANE]

That dry slot to the west looks to be slowly eroding.

http://rammb-slider.cira.colostate.edu/ ... mmb-slider

http://www.ssd.noaa.gov/goes/east/catl/flash-wv.html

[wxman57]

there is definately still a closed circ. weak but its quite visible now on the east side of the dying convection.

ASCAT caught it at 13Z, but didn't indicate any circulation. Lix set it up for the kill with his morning advisory.

[Aric Dunn]

there is definately still a closed circ. weak but its quite visible now on the east side of the dying convection.

ASCAT caught it at 13Z, but didn't indicate any circulation. Lix set it up for the kill with his morning advisory.

http://wxman57.com/images/TD4a.JPG

yeah, I was just mentioning that it still exists .. wouldn't call this a depression any longer. soon to be naked swirl..

still will have to be watched closer to the bahamas..

[wxman57]

Here's the ASCAT image. The red circle is where the NHC put the center around 12-13Z.

[Aric Dunn]

Here's the ASCAT image. The red circle is where the NHC put the center around 12-13Z.

http://wxman57.com/images/ASC.JPG

thats not where it is on satellite.. but not really a big deal at the moment. no convection to call it a TC at the moment. still needs to be watched near bahamas.

[Aric Dunn]

its right about here. still clear eastward moving low level clouds on the south side. its small weak and not a TC without convection.

[Aric Dunn]

shows up even better on RGB

pretty clear .. so I think that the last 24 to 36 hours. keeping it a TD was right on .. but now its just a naked swirl with some high clouds.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html