ATL: HELENE - Post-Tropical

[rainstorm]

its trying to make a come back... some convection firing.

"Do or do not, there is no try!" That convection is south of what looks like a weakening LLC. Oh, and I just measured the last hour's movement at 270 deg and 36 kts.

36 knots? That's going from ludicrous speed heading to plaid. That's going to be incredibly tough to develop at that pace.

yea, but if its clouds hit you at 36 knots thats a tropical storm, hehe.

[tolakram]

Doesn't look any better to me. Firing convection which will probably be left behind in a few hours.

[Kingarabian]

Wait, why is this moving so fast?

[EyELeSs1]

Also our friends at SAB seem to think it is better organized

10/1745 UTC 13.8N 51.1W T1.5/1.5 07L

and UW-CIMSS ADT also suggests something similar:

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 10 AUG 2012 Time : 171500 UTC
Lat : 13:43:35 N Lon : 50:10:37 W


CI# /Pressure/ Vmax
3.1 /1003.5mb/ 47.0kt


Final T# Adj T# Raw T#
2.9 3.2 3.5

[wkwally]

If this makes a come back than paint me blue and call me Babe

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[tropicwatch]

Currently the upper level wind pattern above TD7 is not bad, it is shearing itself because it is moving so fast. Unless something changes, it will run into some actual wind shear and that will probably be all she wrote. In order to survive TD7 would have to slow down and maintain a decent upper level environment.

The shower activity this afternoon does look better.




Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[wxman57]

Wait, why is this moving so fast?

Screaming low level easterly winds that won't likely let up. Yes, it does stil have a circulation, but conditions in its path are more favorable for weakening to a wave than strengthening. Just a few squals for the eastern Caribbean tomorrow.

[knotimpaired]

I'd like to ask a question to the Pro Mets.

Would you please name the top 3 models (Bamms, UKMet, Euro, etc for example) that you would consider have had the best track record for predicted course vs actual course.

[brunota2003]

Nice little burst blew up over the LLC...and just prior to that, you could see the center, it is clearly tight and still very much alive.

[Shuriken]

I have just been looking at the last few frames and it looks like the system is consolidating, nice circular definition can be seen with better cloud coverage .

Agreed. This is a splendid example of a system which is actually being assisted by its marginal environment (e.g., drier surroundings stifling other convection which would otherwise pollute the LLC with outflow boundaries; result is a system which remains focused and can steadily albeit initially slowly intensify; the dry environment will be relatively more unstable as it moistens from the surface during westward progression; i.e., less of a capping problem -- contrast all that to sprawling, sloppy, moist TDs like prote-Ernesto which take forever to get their act together despite seemingly ideal environments).

Wait, why is this moving so fast?

It's not; it's moving at a fairly typical speed for a TD approaching the Windwards.

[Aric Dunn]

the deep convection has expanding and developed over the center with new convection starting on the west side. Also the to the NE of the center where no convection has been able to fire do to the sal is not starting to show some limited convection. looks like it will hang around a little longer.

[ROCK]

Last Advisory still says a modest TS by the NHC at 5 days knocking on the GOM's door....if there is a weakness there at that time or it could just run into the Yucatan.

Forecast in 5 days is for the entire GOM to be protected? I challenge any forecast made after 5 days. Why would the NHC have a huge cone at 5 days. Thats the uncertainty. Even the models have shifted north some and offer a variety of solutions still.

The CMC has this as a TD at the channel, GFDL open but strong wave coming into the SGOM. 12z NOGAPS hits PR...I think we can all agree that this is not dead until it is inland and dissipated.

[Shuriken]

Eyeballing, IMO it's a very small 40kt tropical storm right now.

Not sure where this southwesterly shear is going to be coming from; I'm not seeing any hint of westerly bias in the upstream windbards at any level, nor are there any digging upper-lows ahead (the one to the north is providing a slight northerly regime aloft). If anything, it looks like our TD will ride at the vanguard of the massive blow-off plume of the huge new CV complex exiting Africa.

[Portastorm]

Last Advisory still says a modest TS by the NHC at 5 days knocking on the GOM's door....if there is a weakness there at that time or it could just run into the Yucatan.

Forecast in 5 days is for the entire GOM to be protected? I challenge any forecast made after 5 days. Why would the NHC have a huge cone at 5 days. Thats the uncertainty. Even the models have shifted north some and offer a variety of solutions still.

The CMC has this as a TD at the channel, GFDL open but strong wave coming into the SGOM. 12z NOGAPS hits PR...I think we can all agree that this is not dead until it is inland and dissipated.

I agree ROCK. I think the Gulf picture by the middle to end of next week is questionable. If there is a strong ridge over the Gulf, it'll probably be a narrow one at best. This morning, many of the Texas NWSFOs were talking about how the large and persistent ridge over the central-western US is going to break down. Massive storm system plowing into the US by the middle of next week.

[tolakram]

Eyeballing, IMO it's a very small 40kt tropical storm right now.

Not sure where this southwesterly shear is going to be coming from; I'm not seeing any hint of westerly bias in the upstream windbards at any level, nor are there any digging upper-lows ahead (the one to the north is providing a slight northerly regime aloft). If anything, it looks like our TD will ride at the vanguard of the massive blow-off plume of the huge new CV complex exiting Africa.

Latest shear map



Seven is heading directly toward the area of west / SW shear, which looks to be around 20 kts.

There is also the fact that the lower levels, and the LLC, are moving to the west at over 20kts, which introduces shear in of itself, but combined with 20 kts's of shear from the west / sw it really seems far fetched to think this can survive. Just my opinion, based on how I understand the data.

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Aric Dunn]

well considering its forward motion its probably TS.

[ozonepete]

And don't forget that shear is very fluid and changes quite rapidly at times. So the tongue of higher shear ahead of TD07 could be lower or gone by the time it gets there. It is just a very hard factor to measure well, let alone forecast well.

[tolakram]

And don't forget that shear is very fluid and changes quite rapidly at times. So the tongue of higher shear ahead of TD07 could be lower or gone by the time it gets there. It is just a very hard factor to measure well, let alone forecast well.

No doubt, but i was responding specifically to:

Not sure where this southwesterly shear is going to be coming from; I'm not seeing any hint of westerly bias in the upstream windbards at any level

The shear maps clearly show the SW flow, as it was measured a few hours ago. Shear being a measure of the difference between the flow layers, in this case low and high, not simply a direction of wind.



Here are the high level and low level observed winds from the sat overlay.

[ozonepete]

Yeah I knew you were referring to that, Mark, and your answer (and follow-up now) was very good. I just wanted to point out to others the problems with measuring and forecasting it because so many people read those maps as if they remain the same for days on end, lol.

[ozonepete]

Nice burst still growing over the center...