Atlantic Invest Thread 2010

[kold weather]

Well big changes now occuring with this sytem, its getting a classic severely sheared look, the north of the system is expanding rapidly NE as the storms get caught into the very high shear zone.

It seems the jet stream has dipped a little further south then I was expecting yesterday and this has meant with the combo of 92L lifting out quite quickly the system has not nearly the amount of time in the lower levels of shear then was expected.

The shear maps on the forecasted path of 92L are pretty horrid, a real jet streak is surging through the region to the north of 92L around 13-18N being wound in by a developing TUTT. Shear in 92L's path is something around 35-55kts at the moment and that is the type of shear that will destroy anything. That shear may reduce a little by the time 92L makes it there but we are still looking at 30-40kts of shear in the jet core and simply put, its going to be given a very rough ride.

Only chance it has is to maintain enough energy for it to eventually make it out the other side,but it'd be totally back to square one.

Either way, 40% is massivly too high, I'd say odds of development now over the next 3-4 days probably are as low as 5%, and even that is probably optimistic!

[pyrotech]

Well big changes now occuring with this sytem, its getting a classic severely sheared look, the north of the system is expanding rapidly NE as the storms get caught into the very high shear zone.

It seems the jet stream has dipped a little further south then I was expecting yesterday and this has meant with the combo of 92L lifting out quite quickly the system has not nearly the amount of time in the lower levels of shear then was expected.

The shear maps on the forecasted path of 92L are pretty horrid, a real jet streak is surging through the region to the north of 92L around 13-18N being wound in by a developing TUTT. Shear in 92L's path is something around 35-55kts at the moment and that is the type of shear that will destroy anything. That shear may reduce a little by the time 92L makes it there but we are still looking at 30-40kts of shear in the jet core and simply put, its going to be given a very rough ride.

Only chance it has is to maintain enough energy for it to eventually make it out the other side,but it'd be totally back to square one.

Either way, 40% is massivly too high, I'd say odds of development now over the next 3-4 days probably are as low as 5%, and even that is probably optimistic!

Could they have got it that wrong or are they looking at possibility of it shifting almost directly westwards where it would be following the warmer sea surface temperatures and moving into less severe wind shear. The worst shear, is if it tracks northwards, its alot better to its west. At the moment i see no sign of a westward movement but the temperatures at sea surface drop off quickly just a few hundred miles north. Its not unknown for a system to follow the warm waters but whats your opinion on this. The warm waters 29c - 30c lay in a right angle above the system and cooler water from the north runs in a line from northwest down towards Southeast.

Just a thought ( or clutching at straws)

This is how the models see it for intensity

Edited June 14, 2010 by pyrotech

[kold weather]

They are just going to be conservative probably pyrotech, nothing more then that, believe me that set-up aloft is horrid over the next 48-72hrs. If it can get one big blow up over the center it may just have the time to still become a depression which may also be why they are keeping it at an optimistic 40% but that window is probably less then 12hrs now.

I'm not totally writing off the longer term chances however, if this system can get north of the shear set-up aloft or the jet lifts out fast enough, then it may just have a smil chance past 3-4 days...but over the next 3-4 days its in trouble IMO.

[pyrotech]

Cheers for that Kold.

I have dropped those straws i was clutching now

[kold weather]

Well you never totally know Pyrotech, the great thing about the tropics is it can make mugs out of even the best pros in the world...

But for now the shear is pretty horrible for 92L and its actually only increasing...in fact if you look at the Vis imagery over the next few hours and look to the top right of the screen, you'll see the high level clouds roaring NE/ENE, thats a scale of the shear, usually its not all that obvious on Vis.imagery, the fact we can see it, is a pretty clear sign of just how high the shear is right now.

[pyrotech]

Well i saved the last hours satellite images and to me its now running westwards which could be enough to save it. Obviously if it moves North then as Kold said its game over for a while at least but i got a nagging feeling this will follow the warmer sea surface temps into the carribean. Here is where i see the centre of the depression and its movement ( centre red arrow and red spot and direction in green arrow)

This is totally different from earlier today so it could be a temporrary thing, but i have picked the straws up again.

Will wait now to see what morning brings, things will be clear by then.

[kold weather]

It probably will go into the Caribbean Pyrotech, but not because its following the warmer waters but because a weak system in this set-up will trend further west anyway, esp if it opens up to a wave which is probably going to happen once it gets hit by the shear.

The problem is the shear is a wall in front of it at the moment, the system would have to track probably due west and hope some of the more agressive models are right in lifting the jet streak out quickly to stand any real long term chance. Anything above say 280 and its on for a date with increasing shear which will only get higher and last longer the more latitude it gains now.

ps, I will say once again though it possibly does have 12hrs window to do something, a big Durinal induced blow up over the LLC will have the NHC in a very interesting position...after that things look pretty...well shocking...but I've sorta changed my mind a touch for the next 12-18hrs, shear isn't quite as bad as I thought right over the core, its a tight gradient to the higher shear though, which mans its not far from that shear...but the LLC still looks decent...sooooo, hmmm....

Edited June 15, 2010 by kold weather

[crimsone]

How much trust is the HWRF worth these days?

http://moe.met.fsu.edu/cgi-bin/hwrftc2.cgi?time=2010061418-invest92l&field=Sea+Level+Pressure&hour=Animation

[kold weather]

Pretty much on cue the 12hrs is up and the system is weakening pretty quickly with the convection now weakening very quickly and the LLC is now exposed. Shear is like a wall and is now coming over the top of the system which is causing a very quick weakening. The circulation still looks pretty good for now but as it gets closer to the shear the levels will probably start to seperate and the LLC will start to open up and decay.

Pretty much the end of 92L...for now

Edited June 15, 2010 by kold weather

[Cookie]

92 L

thanks 4 the updates guys

[summer blizzard]

1. AN AREA OF LOW PRESSURE LOCATED ABOUT 1000 MILES EAST OF THE LESSER

ANTILLES IS PRODUCING A FEW DISORGANIZED SHOWERS AND THUNDERSTORMS.

ENVIRONMENTAL CONDITIONS ARE BECOMING LESS FAVORABLE FOR TROPICAL

CYCLONE FORMATION AND THERE IS A LOW CHANCE...20 PERCENT...OF THIS

SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT

MOVES WEST-NORTHWESTWARD TO NORTHWESTWARD AT 10 TO 15 MPH.

The invest has pretty much lost all convection away from some moderate convection in the north west, however it has condenced so it should survive.

http://www.ssd.noaa.gov/goes/flt/t1/bd-l.jpg

Looking ahead, shear will be very high for the next 48 hours, however in about 96 hours, the system should be in more faviourable conditions.

http://www.goes.noaa.gov/GIFS/HUWV.JPG

[Iceberg]

Convection around 92L has exploded overnight, it will be interesting to see how it sustains.

[Iceberg]

It goes to show how difficult shear is to predict sometimes.

As the Shear map shows there is the large wedge of 40+ shear between ex-92L and safety, this is normally enough to totally destroy both convection and the LLCC as KW said.

What seems to be interesting though is the way the precip has really gone crazy over night, shear is still very evident, however shear to the south is much lower and closer to 10kts with nearly 30 Kts to the north of the precip.

The odds are still stacked against further development but if the feature can carry the lower shear environment with it and maintain the precip despite shear upto 35-40Kts then this could be rather special.

[summer blizzard]

Shear should peak in around 48 hours before more favourable conditions.

http://www.ssd.noaa.gov/goes/flt/t1/wv-l.jpg

Plenty of strong convection present now, so i'd expect the system to survive, Alex inj three days anybody?

[kold weather]

Well what we are seeing now is a classic Divergenc e situation...the jet is lifting out slowly and is actually aiding the development of the strong convection. It pobably is a TD right now but it all depends on whether the HC want to pull the trigger.

This one sure is proving a tough one to call, still this is a good warm up for the real season. As for development down the line, I'd certainly keep an eye on it as the shear really isn;'t that bad once you can get to the north of the jet, or if it can stay to the south of the jet streak like it is right now.

[Katherine]

This system appears to be falling apart into a non-event.... from Red to Yellow....

[Rob]

This system appears to be falling apart into a non-event.... from Red to Yellow....

If you read up it seems to be liveing up once again, this could well be a TD/TS in a few days.

[Cookie]

This system is a real fighter and really doesn't know when its beat. its been an interesting watch.

[Iceberg]

Looks like 92L has finally hit the wall of shear. The LLCC is totally exposed of convection at 52 15N.

Shear looks to be around 29-30Kts over the centre and likely to rise to 40Kts over hte next 24 hrs.

Slighly longer term 48 hrs+ and the Jet streak is due to lift from the track with Shear down to 20/25Kts.

It must however be unlikely that the exposed LLCC will survive the Shear.

[kold weather]

Yep Iceberg it really has hit the shear. What happened last night was a classic example of what can happen if the models are even a little bit out.

I didn't get a chance to really explain earlier this morning since my computer was barely running, but the jet streak slightly lifted north overnight and this created stronger upper divergence by helping to effectivly fan the systems outflow and the system was briefly in a more favourable set-up. This allowed convection once again to blow up as a combo of lower convergence and higher level divergence promotes thunderstorm development. We sometimes see that in certain storms, the best one that springs to mind would be hurricane Charley in 2004 when it was moving towards Florida, we saw extremly favourable conditions aloft as the jet streak provided great outflow and very high levels of upper divergence.

On top of that we obviously had overnight durinal influences, with colder upper temps overnight helping to increase lapse rates also helps to deepen the convection and strengthen the system.

Now it has moved into the actual jet streak itself you can see the effect it has with the convection now being blown rapidly eastwards by strong WSW winds.

[Iceberg]

92L is fighting for all it's worth, bless it.

This morning it still had a clear LLCC (against my expectations).

Now it still has the LLCC and it's even capable of firing off a bit of convection (although the shear is blowing it away).

It still has a heck of a time ahead of it for a little while. It is managing to keep a slightly lower area of shear around it at 35-40Kts rather than 45Kts.

It needs to enter into the Caribbean proper though before it can really develop, if it does that, then an estimated long term track might be under Jamaica and then up and over Cuba into Florida, but that's away off yet.

Very much worth watching the visual loops though over the next 24-48 hrs to see if it's still there.

[Katherine]

The NHC have removed 92L from their front page and it now says 'no tropical cyclones at this time' - definitely a non-event now!

[Iceberg]

NHS is right to have removed it from their front page, as this posses not threat over the next 48 hrs to turn into a tropical storm.

However beyond that is a different matter.

It still seems to be doing OK considering.

Essentially as Kold mentioned earlier the Jet is helping instability, which is firing off convection and IMO helping the circulation to stay somewhat intact, (even if it is nolonger closed).

The convection is still be sheared until approx 35kts of shear atm, but....importantly the convection is still firing.

Shear forecasts did have nearly 50kts of shear in the area that the circulation is now, so the instability fired up by the Jet does seem to be allowing the Jet and associated shear to move above the system (at least the really high shear).

beyond 36 hrs and the shear is due to significantly weaken, I wouldn't like to put any kind of chance of what might happen beyond 48 hrs, but the fact it's survived in any way over the last 24 hrs does provide some hint that this system might be a fighter come this weekend.

[Somerset Squall]

The NHC have tagged 92L again. I agree with your post Iceberg, and it seems NHC don't want to completely drop it either. After the 48hr time period, 92L could still be a player.

[summer blizzard]

Anybody got the track for this system, looks to me as though it may hit land limiting development??

92L is entering the peak of the shear now, so conditions will improve.