TC Bertha

[NDG]

Definitely not organizing as I thought yesterday, but given that some models are forecasting it to track WSW over the next 24hrs, tomorrow morning might be a different story.

[KWT]

The problem is Gatorcane conditions look better for it once it gets past 40W and the ECM also does strengthen this again past there after making it into a very weak system before then, SST's will be on the up again once it gets past 40W. For the short term if it doesn't do anything soon then it won't do anything till then.

I wonder what Derek thinks of it?

[boca]

The thought I have in back of my mind is that 92L doesn't develop and moves westward at the lower levels and gets to 60w and boom.Even if the convection goes poof the wave is still there so will have to be watched forflare ups. Only if it doesn't organize.

[KWT]

Exactly Boca because eventually its going to find itself in those warmer waters and also further south then it otherwise would be which would also mean a greater amount of heat content for it to use. I think we have to wait till tonights D-max to see whether this system can do anything or whether any development is going to have to wait some.

[boca]

I posted in the long range model thread about another possible system exiting Africa in the 06zGFS loop,as 92L makes up its mind what to do.

[NDG]

I posted in the long range model thread about another possible system exiting Africa in the 06zGFS loop,as 92L makes up its mind what to do.

Yeah, there is definitely some convergence with that trough about to Exit the coast as seen on the sat loop, which might be a reason why 92L may not be organizing this morning.

[gatorcane]

Of more interest is the dangling trough in the GOM across Florida and into the Bahamas. I think development chances there are higher than with this invest albeit very low still.

[Cyclone1]

Of more interest is the dangling trough in the GOM across Florida and into the Bahamas. I think development chances there are higher than with this invest albeit very low still.

Well... still 20% - 50% according to the NHC. Not very low to me.

[bvigal]

The thought I have in back of my mind is that 92L doesn't develop and moves westward at the lower levels and gets to 60w and boom.Even if the convection goes poof the wave is still there so will have to be watched forflare ups. Only if it doesn't organize.

Boca, I'd say "Bite your tongue!"... but actually, you put in words only what we here in EC fear the most, a big disorganized "blob" of convection, that goes "boom" at 55W. It has happened before.

Also, agree that some reorganizing with next low/wave may be taking place, as some of the models hinted at this, too.

[MiamiensisWx]

This post is NOT an official prognosis.

Back to the topic at hand...

It is likely that the original weak surface low will merge with a broad area of low pressure today. This was not unanticipated; in fact, the operational GFS originally developed a weak surface low (current 92L), followed by a "merge" when the next tropical wave axis approached the coast from the east. It is likely that the wave axis will aid low level convergence and enhance updrafts in the vicinity of the convection further east and southeast, as mentioned by wxman57. Note that the convection south of the Cape Verde islands appears to be weakening or dissipating, while the convection further southeast is maintaining itself via additional thunderstorm development. This is visible to the naked eye with close examination of this loop. Therefore, any cyclogenesis will be much more lethargic, as a new broad LLC could eventually form.

The slower development raises several complex conundrums.

1. SAL. If the primary surface low develops just west of the African coastline (well SE of Cape Verde islands), the system will have more potential issues with the SAL, since a new "surge" has been entering the subtropical eastern Atlantic over the past few days. Therefore, there may be more issues with capping ahead of the system, which would have been slightly less significant if the surface low was further west on the "leading edge" of the 700 mb temp inversion "spill". Note the SAL "surge" on the CIMSS analysis.
2. Steering. If the primary surface low develops further SE as anticipated, it would allow more time for the upper low in the central North Atlantic to deepen and develop to a cutoff low at H5. In fact, the 06Z operational GFS depicts this evolution around 72 hours. This would weaken the strong upper ridging. The new surface low position would also suggest more time for 92L to deepen further east, in which case the mid to upper levels would exert more influence on the steering. Overall, trends suggest that 92L has an increasingly slim chance to even approach the NE Caribbean or Bermuda. Evidence for recurvature is increasingly convincing.

[boca]

This post is NOT an official prognosis.

Back to the topic at hand...

It is likely that the original weak surface low will merge with a broad area of low pressure today. This was not unanticipated; in fact, the operational GFS originally developed a weak surface low (current 92L), followed by a "merge" when the next tropical wave axis approached the coast from the east. It is likely that the wave axis will aid low level convergence and enhance updrafts in the vicinity of the convection further east and southeast, as mentioned by wxman57. Note that the convection south of the Cape Verde islands appears to be weakening or dissipating, while the convection further southeast is maintaining itself via additional thunderstorm development. This is visible to the naked eye with close examination of this loop. Therefore, any cyclogenesis will be much more lethargic, as a new broad LLC could eventually form.

The slower development raises several complex conundrums.

1. SAL. If the primary surface low develops just west of the African coastline (well SE of Cape Verde islands), the system will have more potential issues with the SAL, since a new "surge" has been entering the subtropical eastern Atlantic over the past few days. Therefore, there may be more issues with capping ahead of the system, which would have been slightly less significant if the surface low was further west on the "leading edge" of the 700 mb temp inversion "spill". Note the SAL "surge" on the CIMSS analysis.
2. Steering. If the primary surface low develops further SE as anticipated, it would allow more time for the upper low in the central North Atlantic to deepen and develop to a cutoff low at H5. In fact, the 06Z operational GFS depicts this evolution around 72 hours. This would weaken the strong upper ridging. The new surface low position would also suggest more time for 92L to deepen further east, in which case the mid to upper levels would exert more influence on the steering. Overall, trends suggest that 92L has an increasingly slim chance to even approach the NE Caribbean or Bermuda. Evidence for recurvature is increasingly convincing.

Agreed very good analysis as the ULL gets organized in the CentralAtlantic the shear will tear 92L apart.

[MiamiensisWx]

I think the bottom line is that this one will certainly pose no land threats, regardless of development.

The pattern really isn't exceptionally similar to Bertha '96 at all. Hopefully, most "sane" people realized that is the case.

...and it isn't heading to Texas. If any area is going to receive a remote threat, it will probably be Bermuda.

[KWT]

Very interesting post MiamiensisWx, so you think that the previous wave axis behind this will merge with the current 92L, who knows what will happen after that, the convection is mainly on the eastern side though that is true. Of course the weaker the system remains though the further west it will get before it starts to feel the weakness in the ridge.
I actually think that this system may end up being a possible threat to Bermuda IF it forms, will probably end up going to the east of the islands but its not impossible.

[Extremeweatherguy]

The thought I have in back of my mind is that 92L doesn't develop and moves westward at the lower levels and gets to 60w and boom.Even if the convection goes poof the wave is still there so will have to be watched forflare ups. Only if it doesn't organize.

Yeah, I am more concerned about what this system may do in longer range. I doubt it will develop today, but if it can stay on a westerly course, then it may find a pocket where it could develop once past 40-45W. Wind shear is fairly low over the pocket of ocean east of the islands ( http://cimss.ssec.wisc.edu/tropic/real- ... g8shr.html ), and SSTs start getting pretty warm in that region too ( http://www.aoml.noaa.gov/phod/dataphod1 ... 3atsst.png ). If this is still a well developed wave at that point, then development is definitely a possibility. The only question though is can anything that develops there maintain its strength for long? The wind shear west of 60W and north of 20N caused by the TUTT low may make it pretty difficult (assuming the shear is still as strong in 5-8 days).

[Gustywind]

The thought I have in back of my mind is that 92L doesn't develop and moves westward at the lower levels and gets to 60w and boom.Even if the convection goes poof the wave is still there so will have to be watched forflare ups. Only if it doesn't organize.

Boca, I'd say "Bite your tongue!"... but actually, you put in words only what we here in EC fear the most, a big disorganized "blob" of convection, that goes "boom" at 55W. It has happened before.

Also, agree that some reorganizing with next low/wave may be taking place, as some of the models hinted at this, too.

Yeah Bvigal ,absolutely the worst weather scenario , the nightmare already in early July waouw, i don't like that, hope nothing serious than a strong twave or less, time wil tell, but i believe that past the 40 w conditions should allow for better organization for sure, we can' t ignore that ....whereas for my untrained eyes we have a persistent wave low, always something to watch , don't let our guard down season is just on...

[HURAKAN]

[KWT]

Yeah, I am more concerned about what this system may do in longer range. I doubt it will develop today, but if it can stay on a westerly course, then it may find a pocket where it could develop once past 40-45W.

Yep thats what I'm thinking is a real possiblity. SST's are warm enough once again there and shear doesn't look too high at least at that stage anyway.

Convection looks to be increasing very slowly on that eastern side but still not that impressive yet.

[gatorcane]

Yeah, I am more concerned about what this system may do in longer range. I doubt it will develop today, but if it can stay on a westerly course, then it may find a pocket where it could develop once past 40-45W.

Yep thats what I'm thinking is a real possiblity. SST's are warm enough once again there and shear doesn't look too high at least at that stage anyway.

Convection looks to be increasing very slowly on that eastern side but still not that impressive yet.

The wave should degenerate enough to have about the same probability as any wave does traversing the Atlantic in early July where the probability is low.

Look for the NHC to downgrade development possibilities in their next advisory.

BTW - maybe SHIPs' algorithm needs tweaking. To forecast virtually no shear and rapid intensification never made sense in the first place.

[MiamiensisWx]

This post is NOT an official prognosis.

Back to the topic at hand...

It is likely that the original weak surface low will merge with a broad area of low pressure today. This was not unanticipated; in fact, the operational GFS originally developed a weak surface low (current 92L), followed by a "merge" when the next tropical wave axis approached the coast from the east. It is likely that the wave axis will aid low level convergence and enhance updrafts in the vicinity of the convection further east and southeast, as mentioned by wxman57. Note that the convection south of the Cape Verde islands appears to be weakening or dissipating, while the convection further southeast is maintaining itself via additional thunderstorm development. This is visible to the naked eye with close examination of this loop. Therefore, any cyclogenesis will be much more lethargic, as a new broad LLC could eventually form.

The slower development raises several complex conundrums.

1. SAL. If the primary surface low develops just west of the African coastline (well SE of Cape Verde islands), the system will have more potential issues with the SAL, since a new "surge" has been entering the subtropical eastern Atlantic over the past few days. Therefore, there may be more issues with capping ahead of the system, which would have been slightly less significant if the surface low was further west on the "leading edge" of the 700 mb temp inversion "spill". Note the SAL "surge" on the CIMSS analysis.
2. Steering. If the primary surface low develops further SE as anticipated, it would allow more time for the upper low in the central North Atlantic to deepen and develop to a cutoff low at H5. In fact, the 06Z operational GFS depicts this evolution around 72 hours. This would weaken the strong upper ridging. The new surface low position would also suggest more time for 92L to deepen further east, in which case the mid to upper levels would exert more influence on the steering. Overall, trends suggest that 92L has an increasingly slim chance to even approach the NE Caribbean or Bermuda. Evidence for recurvature is increasingly convincing.

I don't believe the islands along the eastern Caribbean need to be overtly concerned for this one, in my view.

[bvigal]

I think the bottom line is that this one will certainly pose no land threats, regardless of development.

The pattern really isn't exceptionally similar to Bertha '96 at all. Hopefully, most "sane" people realized that is the case.

...and it isn't heading to Texas. If any area is going to receive a remote threat, it will probably be Bermuda.

Miami, some of us are talking about the wave, some are talking about the low currently on the wave. I wouldn't disagree this particular low (92L) will go north. The tropical wave, however, is not going to shoot off into the central Atlantic. It will continue west, just like every other tropical wave does, and a new low could develop on the wave further west. That's what we meant. Oh, and islands are land, you meant 'mainland' right?