North / Over DR ... Cyclone developing

[Steve H.]

Looks to me like a LLCC is taking shape near the Dominican Republic or just to the north. Note the low level turning under the convection and the tail to the SW tucking under. Maybe I'm jumping the gun here, but that's what it looks like to me! Cyclone in formation??? :o

[Stephanie]

It does look like that to me in the satelite. Still needs to close up on the western side though.

[Air Force Met]

Sorry...I don't see it. Still looks very open to me. There is cyclonic turning but there is cyclonic turning in every wave...that's what makes them waves. As far as being closed...don't think that is happening. The cyclonic flow is surely being enhanced in that area due to the proximity of the DR and the southeast flow on teh eastern side.

[Johnny]

I'll have to go with Air Force Met on this one. He did a heck of a job on TD #9 when it lost its punch. No LLC. I will say that convection has increased in the last few frames. Looks nice and healthy.

[alicia-w]

interesting loop

http://wwwghcc.msfc.nasa.gov/GOES/goeseasthurrir.html

[Air Force Met]

Thanks Johnny.

The system has some good convergence...no doubt. It also has some goof outflow aloft...just not the kind that is conducive for tropical development right now. It is getting sheared by some westernly winds but there is good divergence on the downwind side of the system. It is the tropical version of a cold front where you have good convergence along the front and good divergence aloft with the jet...thus you get really good tstms. The diff here is you have 25 and 30 kts westerlies instead of 130 kts. Plus...the system is moving west...not east.

As long as you have westerlies at 20 - 30 kts...and a system moving into that at 15 kts...you have 35-45 kts of vertical shear. Even when the upper winds die down aloft in 24-48 hours to 10 kts or so...you still will have 20-25 kts of vertical shear. This transports all of the latent heat being released by the convection downstream and doesn't allow it to remain with the system so that it can deepen.

Bottom line. This system will have to fight really hard to counter the shear it is experiencing and until the westerly shear relaxes...I don't anticipate much. Plus...the satellite presentation...while it does have some deep convection...remains very poor and indicative of an open wave.

[Johnny]

Good points AFM. When do you see this westerly shear relaxing...at least enough for development to take place?

[wxman57]

Agreed - no evidence at all of a LLC. Those storms are in a VERY high shear zone north of the Dominican Republic. Obs show ENE-ESE winds through the region. Unless convection fires farther south away from the shear, there won't be any development for quite a while (maybe a few days).

[Steve H.]

You are probably right, however what is the low level turning that's evident under and north of the convection? An LLCC can exist when the shear is moderate/high. I'm not saying there is one, that is an exclusive statement...shear = no llcc.

[alicia-w]

this looks better than it did a few hours ago

[Air Force Met]

Steve...can you give a lat/long where you see the turning?

Yes...you can have a LLC with shear. However, in most cases the LLC would need to be present before the shear started...not formed in a strong shear environment.

[wxman57]

There are a lot of sfc obs in that area and all show ENE-ESE winds. There is no LLC.

[Anonymous]

Steve if this helps the Prof. Met in Brownsville just said that they are monitoring the area of 20.3 and 72.4 for an LLC due to the shear is collapsing in the area and it is much more favorable within next 12 to 24 hours for development. I dunno if it will help but that is what he said.

[Steve H.]

Nope....no LLCC. The area of cyclonic turning I thought I noted was well to the NE and N of the main convection. Looked to be N /NE of DR, partially masked by the convection. Since the convection died off, I see nothing to indicate there was an LLCC....my mistake. Conditions should be improving for development later tomorrow....shear seems to be easing up. Cheers!!

[obxhurricane]

Good points all around. Indeed this system remains an open wave...at least in my opinion. To me the most intriguing stat of the night is the low surface pressures around 1010 mb in the area. Once the shear relaxes, it wont take much for a LLC to develop.

[wxman57]

Wouldn't it be nice if NOTHING at all developed all this week and I got to take Saturday, Sunday, AND Monday of Labor day off for once?

Nah...

[Anonymous]

Wxman57 would you settle for Christmas Eve and Christmas ?