Invest 94L,Near Windwards-Discussions

[MWatkins]

Although conventional satellite imagery is relatively unimpressive, morning QSCAT imagery shows a pretty healthy looking western side to the wave (although the swath missed the eastern half of it):

http://manati.orbit.nesdis.noaa.gov/dat ... MBas26.png

I am guessing this is stretched in the horizontal…which is why it has such a flat satellite presentation.

One issue with looking at the deep layer BAM guidance is that it assumes this will be a deep layer system from the get-go. Obviously, this is not a deep layer system yet.

Although systems have tracked into SA in the past, the vast majority do not “slam into” land down there. I am going to hold off on a projected track until we actually have something numbered to track…but I’d like to see a couple of runs of the globals (including GFDL and HWRF) before biting on that idea. It’s a strong ridge, sure, but we don’t have a deep system yet.

I think this is going to take it’s time and get gradually better organized over the next couple of days. There is plenty of moisture in the envelope, but until it gets an inner core established it is not going to bomb out. And this system is going to have a tough time putting itself together moving westward at 20 knots.

The global models…in general…are sensing the pattern is changing. The Euro, GFS and UKMET are all starting to develop cyclones.

MW

[skysummit]

Convection is blossoming over the LLC.

[ronjon]

Both the 00Z CMC and Euro have remarkable consistency in bringing the system to the middle Leeward Islands in 6 days. Their 6-day positions appear to be within 100 miles of each other. Looking at the 500 mb pattern, there is a large low pressure system and trough around 33N-40W in 72 hrs in the Euro model. Perhaps in these models the system is getting tugged slightly northward due to this weakness. Or they are simply reflecting a weaker Atlantic ridge than the BAMs. Both globals only slowly develop the cyclone and don't identify it as a tropical storm until 4-5 days from now.

[cycloneye]

Does not look too bad.

[otowntiger]

conditions are quite favorable for rapikd intensification if this ever comes together

I guess this is somewhat of a philosophical question, but if the conditions truly are quite favorable for rapid intensification, why isn't it intensifying now? It probably is because we still don't have a good handle on intensity forecasts, because based on all we know, the conditions are favorable, but something unknown is prohibiting it, right?

Note Ortt's last words...."if this ever comes together". That's why....it's not yet together yet.

That's my whole point. "If it comes together". What keeps systems like this from coming together? Something that we cannot explain or don't know. I'm not knocking anyone here, I'm just raising a theoretical question. I believe someone else earlier in this thread was touching on the subject. If conditions are so favorable, why don't they develop? I believe it is because we simply don't know all the factors, and the experts generally admit that. They will say that conditions "appear to be favorable" but if a system doesn't develop from a wave or rapidly intensify as it should based on all the factors that we know about, we are at a loss.

[skysummit]

That's my whole point. "If it comes together". What keeps systems like this from coming together? Something that we cannot explain or don't know. I'm not knocking anyone here, I'm just raising a theoretical question. I believe someone else earlier in this thread was touching on the subject. If conditions are so favorable, why don't they develop? I believe it is because we simply don't know all the factors, and the experts generally admit that. They will say that conditions "appear to be favorable" but if a system doesn't develop from a wave or rapidly intensify as it should based on all the factors that we know about, we are at a loss.

Take a look at it right now. It is coming together. It's a slow and delicate process. Not every wave will develop, even under the most pristine conditions. This one, however, looks like it has everything going for it so development chances, IMO, are looking better and better.

[wxman57]

One other thought. I see talk of it reaching the Caribbean in 5 or 6 days. It's currently 1350 miles from the Caribbean. If it moved at the current speed of 23 mph (20 kts), then it would reach the Caribbean in 60 hours, not 6 days. If it slows to 18 kts, then it would reach 61W in about 69 hours. To reach the eastern Caribbean in 96 hours, as suggested by the BAMM, it would have to slow down to just over 13 kts. With a strong ridge to the north, I'd go with the faster forward speed than a big slow-down. And that means almost a due west track.

[Meso]

Like I said earlier before.. For a system to develop from an open wave,it first needs to consistent convection and form a low level circulation.A bunch of thunderstorms turning into a depression is more work than an already formed circulation to intensify,it's just about the earlier stages needing more work.Or so I think

[Derek Ortt]

Mike,

from the BAM suite, a deeper system would be more likely to hit SA than a shallow system. The shallow BAM is well north of the medium and deep

[Derek Ortt]

this almost certainly will be in the Caribbean (or over SA) within 72 hours... I have no clue what the global models are seeing

[gatorcane]

It definitely looks like it is on its way to development....I'm not sold on a track into SA just yet. This one could get interesting for the Caribbean again should it miss SA.

[skysummit]

For those of you who like to use the GHCC Sat software, 94L is in the GOES-E NHE sector. It's starting to look real good on visible.

[Derek Ortt]

I am able to see hints of a surface circulation on the visible satellite this morning. This could become a TD within the next 48 hours. I would give this a 30 percent chance of developing now, compared to 5 yesterday

[skysummit]

I am able to see hints of a surface circulation on the visible satellite this morning. This could become a TD within the next 48 hours. I would give this a 0 percent chance of developing now, compared to 5 yesterday

0% chance now Derek? LOL I'm sure that's just a typo.

[DESTRUCTION5]

I am able to see hints of a surface circulation on the visible satellite this morning. This could become a TD within the next 48 hours. I would give this a 0 percent chance of developing now, compared to 5 yesterday

Conflicting facts?

[otowntiger]

One other thought. I see talk of it reaching the Caribbean in 5 or 6 days. It's currently 1350 miles from the Caribbean. If it moved at the current speed of 23 mph (20 kts), then it would reach the Caribbean in 60 hours, not 6 days. If it slows to 18 kts, then it would reach 61W in about 69 hours. To reach the eastern Caribbean in 96 hours, as suggested by the BAMM, it would have to slow down to just over 13 kts. With a strong ridge to the north, I'd go with the faster forward speed than a big slow-down. And that means almost a due west track.

"And that almost a due west track", and perhaps a weaker system? Doesn't the faster motion also many times prevent, or appear to prevent rapid development?

[Derek Ortt]

This is going to be one of those days... somehow I typed 30 percent as 0 percent

[MWatkins]

Mike,

from the BAM suite, a deeper system would be more likely to hit SA than a shallow system. The shallow BAM is well north of the medium and deep

Hi Derek...

I am with you. If everything were based of the BAM guidance...I would not expect this to go charging into SA as long as it remains a shallow system. BAMD assumes it's a deep layer system right now and will be so through the fcst period...when it's probably not a deep layer system.

Of course if it is still moving at 270/20 Thursday morning...well...

Also...on another note looks like we have some easterly shear based on the cloud pattern. Not tons...but some.

MW

[Derek Ortt]

everyone, we need to stop thinking that fast movement prevents development. Did we already forget what we saw with Dean... a system moving faster than 20KT that still rapidly intensified. Also, we need to forget that weak means west. Weak means steered with the low level flow, which this time means a more northerly track

I can see some slowdown of this feature since there is little SAL; however, not much of a slowdown is likely

[Derek Ortt]

SHIPS has the shear vector at 140 degrees and 11KT... should be favorable enough for development if this convection persists