ATL: INVEST 92L - Discussion

[tolakram]

live loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=15

If you drop the bad frames you can kind of see the center reforming. ... maybe

[Javlin]

To a layman such as I.I think you might be correct in that assumption.

[ozonepete]

Btw, I would say 2 things here: First,this is truly one of the most complicated developing TC situations I have ever seen, and I've seen a lot - all of us here have. Second, if this develops from where I have it circled and becomes a TS and moves north to the central Gulf coast, the new and improved GFS can probably really be called improved and gets another big win over the Euro.

Ozonepete:

As you know I'm half a world away right now and most images in these threads don't appear behind the great firewall of China, so bear with me...

Even though I can't see the pictures, it sounds like there's some chance that this northern vort you've described has its genesis in an old cold-core upper low. Is it perhaps going to be a Subtropical Storm, not a tropical storm (at least at first), assuming something works down to the surface?

Or are models, synoptic analysis, etc. predicting more of a warm core look? It sounds like given this complex genesis, there could be some hybrid-ness, but as I said, all I have in front of me right now is what I'm reading, so set me straight, please.

Lol, the great firewall has deceived you, my son. All of the vorticity came from a developing tropical disturbance that moved from the northwest Caribbean over the Yucatan. The euro consistently had it move over the southern Yucatan and develop in the BOC and hit southern Texas or northern Mexico. The GFS pretty consistently took it to the northern Yucatan and then developed it in the GOM and took it north to Louisiana. In reality the whole disturbance reached the Yucatan and the vorticity stretched from north to south, with a vort max over the southern central Yucatan and another over the northern Yucatan last night. Meanwhile, a ULL dropped south into the Gulf and complicated things by pulling the mid-level convection/MLC northward to the north of the Yucatan and the LLC went westward in the low level flow to just off the western Yucatan coast. During the day today the LLC at first looked like it could develop again but the ULL dropped further south but weakened and then seemed to merge with the northern area of vorticity/MLC. This is continuing to develop now. The southern LLC west of the western Yucatan dissipated. So the "northern vort" was completely tropical and the ULL was a local fairly small ULL that could not be considered as something sub-tropical or non-tropical. There are no fronts or cool or dry air associated with any of this. So nothing sub-tropical. You really need pictures my friend.

[Alyono]

18z GFS now with the northern vort heading to the Mobile, AL area showing 43kt winds at 850mb.

That is sort of a concern considering how easily this could become Tropical, we all know these models are not so great with intensity. This Vort would also cross over some of the warmest SST's in the Gulf over 30C.

IF this moves north, its dead. Going to get blasted apart by shear. That is clear as day

The NGOM is getting squally weather and gusts as high as 60 mph in the squalls, but not a tropical storm.

[wjs3]

Ozonepete:

As you know I'm half a world away right now and most images in these threads don't appear behind the great firewall of China, so bear with me...

Even though I can't see the pictures, it sounds like there's some chance that this northern vort you've described has its genesis in an old cold-core upper low. Is it perhaps going to be a Subtropical Storm, not a tropical storm (at least at first), assuming something works down to the surface?

Or are models, synoptic analysis, etc. predicting more of a warm core look? It sounds like given this complex genesis, there could be some hybrid-ness, but as I said, all I have in front of me right now is what I'm reading, so set me straight, please.

Lol, the great firewall has deceived you, my son. All of the vorticity came from a developing tropical disturbance that moved from the northwest Caribbean over the Yucatan. The euro consistently had it move over the southern Yucatan and develop in the BOC and hit southern Texas or northern Mexico. The GFS pretty consistently took it to the northern Yucatan and then developed it in the GOM and took it north to Louisiana. In reality the whole disturbance reached the Yucatan and the vorticity stretched from north to south, with a vort max over the southern central Yucatan and another over the northern Yucatan last night. Meanwhile, a ULL dropped south into the Gulf and complicated things by pulling the mid-level convection/MLC northward to the north of the Yucatan and the LLC went westward in the low level flow to just off the western Yucatan coast. During the day today the LLC at first looked like it could develop again but the ULL dropped further south but weakened and then seemed to merge with the northern area of vorticity/MLC. This is continuing to develop now. The southern LLC west of the western Yucatan dissipated. So the "northern vort" was completely tropical and the ULL was a local fairly small ULL that could not be considered as something sub-tropical or non-tropical. There are no fronts or cool or dry air associated with any of this. So nothing sub-tropical. You really need pictures my friend.

They are, after all, worth a thousand words, as proven here. Thanks! I didn't see the purely tropical origins of the northern vort. Sounds pretty darn cool and complicated in evolution and I'll look forward to catching up when I can.

I'm back Saturday, US time. Can't wait!

[Alyono]

Why did NHC LOWER the development chances?

[cycloneye]

Why did NHC LOWER the development chances?

Good question.

AN AREA OF LOW PRESSURE IS LOCATED OVER THE SOUTHWESTERN GULF OF
MEXICO ABOUT 110 MILES NORTHWEST OF CAMPECHE MEXICO. THIS SYSTEM
REMAINS POORLY ORGANIZED WITH ANY ASSOCIATED SHOWER AND
THUNDERSTORM ACTIVITY LOCATED WELL TO THE EAST AND NORTHEAST OF THE
LOW CENTER. ENVIRONMENTAL CONDITIONS COULD BECOME SOMEWHAT MORE
FAVORABLE FOR DEVELOPMENT WHILE THE LOW GENERALLY MOVES TOWARD THE
WEST-NORTHWEST OVER THE NEXT COUPLE OF DAYS. INTERESTS IN THE
CENTRAL AND WESTERN GULF OF MEXICO SHOULD MONITOR THE PROGRESS OF
THE SYSTEM THROUGH THE WEEKEND. THIS SYSTEM HAS A MEDIUM
CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS...AND A MEDIUM CHANCE...50 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

[Dean4Storms]

18z GFS now with the northern vort heading to the Mobile, AL area showing 43kt winds at 850mb.

That is sort of a concern considering how easily this could become Tropical, we all know these models are not so great with intensity. This Vort would also cross over some of the warmest SST's in the Gulf over 30C.

IF this moves north, its dead. Going to get blasted apart by shear. That is clear as day

The NGOM is getting squally weather and gusts as high as 60 mph in the squalls, but not a tropical storm.

Yea most likely, I agree. Still need to watch it, if it was to develop rapidly before getting into the higher shear it could become tropical and with enough forward speed present TS like conditions. A mess I know.

[Alyono]

I really cannot understand the logic. The low is better defined and an upper high is building over the system.

Yes, if this develops, it is almost certainly not going to be strong at all. Maybe an Arlene 1993 in terms of intensity and structure.

I simply strongly disagree with lowering the development chances

[ozonepete]

Why did NHC LOWER the development chances?

I agree with Luis. Good question. I would have left it the same. Nothing from today changed the equation. I wouldn't have touched the numbers until I see what happens tonight and tomorrow.

[Stormcenter]

I believe they are still focusing on the swirl from this morning that to be honest with I personally cannot locate any longer on sat. IMO

Why did NHC LOWER the development chances?

Good question.

AN AREA OF LOW PRESSURE IS LOCATED OVER THE SOUTHWESTERN GULF OF
MEXICO ABOUT 110 MILES NORTHWEST OF CAMPECHE MEXICO. THIS SYSTEM
REMAINS POORLY ORGANIZED WITH ANY ASSOCIATED SHOWER AND
THUNDERSTORM ACTIVITY LOCATED WELL TO THE EAST AND NORTHEAST OF THE
LOW CENTER. ENVIRONMENTAL CONDITIONS COULD BECOME SOMEWHAT MORE
FAVORABLE FOR DEVELOPMENT WHILE THE LOW GENERALLY MOVES TOWARD THE
WEST-NORTHWEST OVER THE NEXT COUPLE OF DAYS. INTERESTS IN THE
CENTRAL AND WESTERN GULF OF MEXICO SHOULD MONITOR THE PROGRESS OF
THE SYSTEM THROUGH THE WEEKEND. THIS SYSTEM HAS A MEDIUM
CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS...AND A MEDIUM CHANCE...50 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

[NDG]

Right we think that 92L might be getting its act together the NHC lower the chances of development.

[Dean4Storms]

I might be looking at sat. loops too much today, but is anyone else seeing what looks like an Anti-cyclone getting established aloft over this once ULL?

[HurriGuy]

I know everyone has said it but I can't believe they lowered it.

[NDG]

It looks to me that an LLC has formed or trying to form underneath the dying mid and UL low, near 22.5N & 90.1W based on the last visible satellite pixs, but it could be just rotating around a bigger circulation.

[SoupBone]

Right we think that 92L might be getting its act together the NHC lower the chances of development.

And then there's sensationalism.

"CNN Meteorologist Chad Myers says a disturbance in the Gulf of Mexico could potentially explode into a big storm."

http://www.cnn.com/video/data/2.0/video/us/2013/08/16/tsr-chad-myers-tropical-activity-in-gulf.cnn.html

[NDG]

I might be looking at sat. loops too much today, but is anyone else seeing what looks like an Anti-cyclone getting established aloft over this once ULL?

Yes, you are correct, and the GFS forecasts for the UL antycyclone to keep building over the central and eastern GOM through the weekend.

[ozonepete]

I might be looking at sat. loops too much today, but is anyone else seeing what looks like an Anti-cyclone getting established aloft over this once ULL?

Well not quite yet, but I do see good upper outflow on the northern, eastern and southeastern sides. That could help it to eventually get a full upper anti-cyclone to develop over it.

[BigA]

Assuming two things, I think 92L has a good chance of getting together:

1) A low-level circulation is forming/reforming northeast of the old LLC, where there is substantial turning on visible images.

2) 92L moves primarily on a westward, rather than northward heading.

If these things come together, I think 92L should find a sufficiently favorable environment to become a TC. Note that the 18Z SHIPS, which predicts a primarily westward motion, never has shear rise above 17kts. Shear is tough to forecast, but this is a lot less than the 20-30 kts it was forecasting even earlier today.

[ozonepete]

It looks to me that an LLC has formed or trying to form underneath the dying mid and UL low, near 22.5N & 90.1W based on the last visible satellite pixs, but it could be just rotating around a bigger circulation.

Yup. I see 22.5N between 90 and 91W.