ATL: TROPICAL DEPRESSION HENRI (10L)

[HURAKAN]

Aric, I agree that it looks like a depression or maybe a minimal tropical storm. Only a RECON mission would solve that problem but there won't be a RECON mission.

[Aric Dunn]

if it forms, it is out of here

CMC does develop this but shoots it straight north, then stalls it. Not enough ridging to drive this west

umm.. derek I would look again .. as the cmc does drive it south ... http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[Evil Jeremy]

if it forms, it is out of here

CMC does develop this but shoots it straight north, then stalls it. Not enough ridging to drive this west

umm.. derek I would look again .. as the cmc

There, I simplified your post Aric lol. Its the CMC, nuff' said. Even with recent improvements, it still is not the most reliable.

[HURAKAN]

Shear blowing the convection away

[wxman57]

http://metofis.rsmas.miami.edu/~dortt/satellite/C_Atl/IR/atl_ir1_loop.gif

Convection continues to build over the LLC.

You can't really see the lower-level circulation on that loop, though. Take a look at a high-res visible and you can see the convection now beginning to run into increasing shear. It's separating from the weak lower-level circulation again. It's not a TD or a TS. There's no evidence of an LLC either in the surface obs in the region or with QS. That spin is above the surface, and it's pretty weak.

[gatorcane]

if it forms, it is out of here

CMC does develop this but shoots it straight north, then stalls it. Not enough ridging to drive this west

I agree if it bombs out into a hurricane. But that isn't happening so it will just keep going WNW. 12Z NAM bends it back West...but thankfully weakens it:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_054l.gif

[Evil Jeremy]

I don't think this had much of a chance to begin with. I did not even need to look deeply into shear charts to remember that this is 2009. This won't survive, and while it looked like it was coming close to forming yesterday (once again, the key word being "looked"), 91L is no where near forming now. Convection needs to persist, not blow up and fall apart and repeat.

[Aric Dunn]

This buoy more than 100 miles away ... earlier this morning had a pressure 1009 MB

http://www.ndbc.noaa.gov/station_page.php?station=41nt0

and again this buoy 200 miles from the center is far outside the circ..
http://www.ndbc.noaa.gov/station_page.php?station=41040

[HURAKAN]

Loop: http://rammb.cira.colostate.edu/ramsdis ... _floater_2

Compared to Danny and Erika, not looking that bad

[StarmanHDB]

Hi everyone!

Although I've been following the forums for a while, this is my first post. I'm definitely not an expert, but I do find tropical weather a very interesting subject and I try to follow tropical waves/storms throughout their lifespans.

All of that said, will someone please explain to me what the latest burst of convection means to the development of 91L? Thanks, and I'm looking forward to the education which I'm about to receive by reading your responses.

[HURAKAN]

Danny at it's first advisory:



91L:



Given, Danny had a well-developed LLC

[HURAKAN]

Loop: http://rammb.cira.colostate.edu/product ... 162345.GIF

Another great loop

[HURAKAN]

Latest

[Sanibel]

All of that said, will someone please explain to me what the latest burst of convection means to the development of 91L? Thanks, and I'm looking forward to the education which I'm about to receive by reading your responses.

It just means the Low has enough energy to create a convection burst. Development is just a simple matter of the storm being stronger than surrounding conditions. Right now the surrounding conditions, especially shear, are stronger so the storm can't get vertically alligned. That's why you see the surface spiral outside and separate from the convection.


I had a feeling this wasn't headed for the Caribbean.

[Nimbus]

91L just spit one vortex out from under the convection. If that is the primary LLC it was fairly well formed and not elongated. Development will be slow till the LLC starts picking up convection again, and the shear has fortunately been persistent enough to keep this system from bombing into a hurricane. If the LLC stays naked it will move west too fast to get picked up by the trough. The track north of the islands keeps the wind threat down somewhat but I'm not sure what will happen once this gets under the ridge.

[wxman57]

Here's a close-up of the little vortex, which probably is a small LLC:


Closer...

[HURAKAN]

Nimbus, I think that's the LLC, not just a vortex. It was not spit out by the convection, it's moving NW, just that the shear is pushing the convection east of the center. Like I said before, there's not much difference between Danny and 91L.

Loo: http://rammb.cira.colostate.edu/ramsdis ... _floater_2

[wxman57]

Nimbus, I think that's the LLC, not just a vortex. It was not spit out by the convection, it's moving NW, just that the shear is pushing the convection east of the center. Like I said before, there's not much difference between Danny and 91L.

Loo: http://rammb.cira.colostate.edu/ramsdis ... _floater_2

No, not a lot of difference between the two - a good argument that Danny should not have been named, perhaps.

[gatorcane]

91L just spit one vortex out from under the convection. If that is the primary LLC it was fairly well formed and not elongated. Development will be slow till the LLC starts picking up convection again, and the shear has fortunately been persistent enough to keep this system from bombing into a hurricane. If the LLC stays naked it will move west too fast to get picked up by the trough. The track north of the islands keeps the wind threat down somewhat but I'm not sure what will happen once this gets under the ridge.

Yes, it's the "once it gets under the ridge" part that I am curious about. What will happen then?

[HURAKAN]

No, not a lot of difference between the two - a good argument that Danny should not have been named, perhaps.

It's the same problem with many sheared systems. How sheared can it system be to not be classified as a tropical cyclone? I think that if it has a well-defined LLC and organized convection, then it's a tropical cyclone, even if it's sheared.