ATL: BERTHA - Post-Tropical - Discussion

[NDG]

93L is skimming south of an area of very dry air with fairly high winds. IMO much of that 45kt wind the hunters are finding is not the tropical low, but apart of the SAL push.

http://i794.photobucket.com/albums/yy22 ... 30da09.png

There is some nice pressure gradient to the north of 93L which has a pressure of around 1007-1008mb, pressures to the north of it are much higher around 10014-1015 mb in a relatively short distance.

[ninel conde]

Some low clouds wrapping in... Nice little circulation...

looks par for the course the last few seasons. i expect it might find some moisture as it trucks on NE in a few days.

[NDG]

From Today's CSU forecast update, this is how bone dry July was in the Atlantic at H60, they think is the driest ever. No wonder TD2 and 93L have struggled so much.
Very weird when the sub Saharan area in Africa has had wetter than normal wx.

[ninel conde]

From Today's CSU forecast update, this is how bone dry July was in the Atlantic at H60, they think is the driest ever. No wonder TD2 and 93L have struggled so much.
Very weird when the sub Saharan area in Africa has had wetter than normal wx.

the desert conditions extend well into the atlantic north of the tropics as well.

[Sanibel]

The dry air is winning. It could re-fire but will it survive the Caribbean?

[Frank2]

I always find it ironic that the air can be so dry over so much water...

P.S. I did see the photo of 93L on the previous page - not very impressive at all...

[northjaxpro]

For a organized tropical cyclone to be designated, convection must be around or very close within the center of circulation, which we simply do not have at this time. I think 93L is on its last legs right now. The system is really up against it with the dry air and later on shear down the road. Unless we see convection fire later tonight around the LLC, 93L will be history and a Bones sighting will be on this thread very soon. We will see what happens tonight.

[NDG]

The dry air is winning. It could re-fire but will it survive the Caribbean?

I think the only area it can do anything is north of the Greater Antilles, east of US Atlantic coast, where best conditions in the Atlantic have been more often than not.

[gatorcane]

The dry air is winning. It could re-fire but will it survive the Caribbean?

I think the only area it can do anything is north of the Greater Antilles, east of US Atlantic coast, where best conditions in the Atlantic have been more often than not.

Actually looking at the GFS, conditions across the entire Caribbean become quite favorable in about 72 hours (at least from a shear perspective) with that screaming shear dropping off, just in time for August. Actually I see a large anticyclone centered over the South-Central Caribbean in about 5-6 days from now. Fortunately this system is not heading west across the Caribbean.

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.

[NDG]

I always find it ironic that the air can be so dry over so much water...

P.S. I did see the photo of 93L on the previous page - not very impressive at all...

There is always fairly humid air at the surface but without widespread instability there is nothing to make that moist air rise to the mid levels of the atmosphere after convection forms. But yes, I know what you mean that one would think that the atmosphere would automatically be moist over such a large ocean.

[NDG]

The dry air is winning. It could re-fire but will it survive the Caribbean?

I think the only area it can do anything is north of the Greater Antilles, east of US Atlantic coast, where best conditions in the Atlantic have been more often than not.

Actually looking at the GFS, conditions across the entire Caribbean become quite favorable in about 72 hours with that screaming shear dropping off, just in time for August. Fortunately this system is not heading west across the Caribbean.

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.

Yes, I have been seeing the GFS show that but I don't believe it until I see it, but there is always the threat for low level shear which could be even more destructive.

[MGC]

Surprised by the low pressure and high winds. I bet some will argue that 93L was likely a TS very early this morning when the convection was more robust. So, what will the NHC do? Here we have a naked swirl with TS winds headed towards populated islands? Upgrade, or let the island weather bureaus handle it?....MGC

[SouthDadeFish]

Keep in mind there are other ways to get dry air in the mid-levels of the atmosphere other than SAL. Subsidence is another primary way. Anyway, I think the shear vorticity associated with the strong low-level trades is what has kept the circulation so vigorous despite the lack of convection. The swirl will begin to lose this shear vorticity as it gains latitude.

[northjaxpro]

Surprised by the low pressure and high winds. I bet some will argue that 93L was likely a TS very early this morning when the convection was more robust. So, what will the NHC do? Here we have a naked swirl with TS winds headed towards populated islands? Upgrade, or let the island weather bureaus handle it?....MGC

No upgrade unless convection bursts near the LLC. I would be very surprised if NHC pulled the trigger right now.

[TJRE]

CIMSS check-in



to B or not to B..... that is the question

http://tropic.ssec.wisc.edu/

[Frank2]

In the NHC days forcaster Gil Clark would call them "screaming easterlies" of 40-50 kts that came behind a wave axis...

P.S. Thanks for that explaanation, NDG - makes sense...

['CaneFreak]

Ding ding ding. We have a winner. Best post I have read all day. Shear vorticity is the only thing keeping this thing alive. 41 degree dewpoint depressions were found at 500 mb this afternoon just east of Guadeloupe. Horrid out there.

Keep in mind there are other ways to get dry air in the mid-levels of the atmosphere other than SAL. Subsidence is another primary way. Anyway, I think the shear vorticity associated with the strong low-level trades is what has kept the circulation so vigorous despite the lack of convection. The swirl will begin to lose this shear vorticity as it gains latitude.

[NDG]

Perhaps it wouldn't hurt to have special flight missions in the MDR for the remainder of the hurricane season sampling the atmosphere to keep hurricane models from over developing tropical waves that way the NHC will have a better idea of what percentage to give for development. IMO.

[RL3AO]

Perhaps it wouldn't hurt to have special flight missions in the MDR for the remainder of the hurricane season sampling the atmosphere to keep hurricane models from over developing tropical waves that way the NHC will have a better idea of what percentage to give for development. IMO.

I don't think its a data problem. Models are clearly showing how dry it is.

[Evil Jeremy]

Not to give anyone a headache (well, a bigger one), but convection is popping again, on the right side of the LLC. It was around this time last night that convection started refiring, and held into the night.