Invest 99L Thread #6

[skysummit]

Yea....regarding my theory....remember, the chances of this happening or low to NIL, but since there's really nothing else to talk about, I'd like to hear a pro met's thoughts on it. Don't just shut it down simply because it likely won't happen....try to keep an open mind

[punkyg]

Hey where did my post go?

[vaffie]

Yea....regarding my theory....remember, the chances of this happening or low to NIL, but since there's really nothing else to talk about, I'd like to hear a pro met's thoughts on it. Don't just shut it down simply because it likely won't happen....try to keep an open mind

I'm not a pro, but in my 15 years of watching storms develop, I've seen the scenario you painted countless times. We'll just have to wait and see. The models take it in the general direction of the Yucatan already, so reformation to the north would simply take it through the channel--a bad scenario if you're worried about development.

[tailgater]

I have a question for those more knowlegdeable than myself. Is mid level energy just as likely to react to diurnal Max's and Min's as low-level energy?

When the diurnal max comes after dark, the reason you get stronger convection (tstorms) is that the cloud tops of whatever showers and thunderstorms are there radiate energy out into space and thus cool down. Cooler temperatures at the tops of these clouds increases the temperature difference between the warm sea surface and the tops of the clouds. This steeper temperature diference causes the air to rise higher and faster, i.e. the thunderstorms grow in size. It's a positive feedback loop that goes on until the sun comes back out.
So given that, all energy levels from low to mid to upper are affected in the sense that they all see a kinetic energy increase due to air rising higher and faster within the disturbance. If by lower levels you mean the surface, even there we must see an energy increase, since the surface air gets drawn in faster as the divergence increases at the top levels.

I'm a mad scientist, (not officially a meterologist), but that was a great explanation of diurnal convection. This is the same reason that thunderstorms break out during the day over land. Does anyone know what height in the atmosphere this "cooling" takes place at so as to trigger nighttime convection? Also, does anyone have maps that chart this type of instability (difference in temp between lower and upper levels)... is this the same as the lifted index?

Another comment: Perhaps this a contributing factor for why tropical activity picks up in Autumn... peak water temps from a season of heating, with an upper atmosphere that is colder because nights grow longer, hence more convection, and in turn more cyclones.

Thanks for your insight Phil, good stuff, but I guess I didn't explain myself very well. If there is no energy at the surface will this heat transfer still take place. The reason I ask is because IMHO(uneducated weather nerd) I didn't think that 99l ever had much at the surface, yet it was greatly effected by the diurnal Max each evening or was that happenstance, maybe cloud deck keeping the surface cooler until the sun broke through?
Just trying to learn something, please excuse all the grammer errors.

[Sanibel]

I think the wave is already being drawn towards the trough over the GOM. It still has that red ir attached to it.

[philnyc]

I'm a mad scientist, (not officially a meterologist), but that was a great explanation of diurnal convection. This is the same reason that thunderstorms break out during the day over land. Does anyone know what height in the atmosphere this "cooling" takes place at so as to trigger nighttime convection? Also, does anyone have maps that chart this type of instability (difference in temp between lower and upper levels)... is this the same as the lifted index?

Another comment: Perhaps this a contributing factor for why tropical activity picks up in Autumn... peak water temps from a season of heating, with an upper atmosphere that is colder because nights grow longer, hence more convection, and in turn more cyclones.

The daytime tstorms over land are caused by a different mechanism.
The height that the cooling takes place in the diurnal variation we talked about is always at the height of the cloud tops, which can be anywhere from roughly 12-15,000 feet in shallow systems to 60 or even 70,000 feet in the mighty systems like Katrina or Rita.
Charts of these temp differences with height are called skewT diagrams or soundings.
Here's a good definition of the Lifted Index:
http://www.weather.gov/glossary/index.php?word=lifted+index

Sorry, I'm on lunch and had to rush this...

[MGC]

99L behavior to date is just as I expected. I've been saying that development if any would not occur until 99L reached the W. Carb. Sea. 99L should start slowing down soon, at at time the chances improve slightly. It will likely hit land before it spins....MGC

[philnyc]

Thanks for your insight Phil, good stuff, but I guess I didn't explain myself very well. If there is no energy at the surface will this heat transfer still take place. The reason I ask is because IMHO(uneducated weather nerd) I didn't think that 99l ever had much at the surface, yet it was greatly effected by the diurnal Max each evening or was that happenstance, maybe cloud deck keeping the surface cooler until the sun broke through?
Just trying to learn something, please excuse all the grammer errors

Unfortunatley I won't be back here til later today. But quickly, there is always a LOT of energy over water that warm. Any mechanism that can lift it, such as an eastery ave in this case, will cause it to lift quite high into tall tstorms, provided other criteria are present.
This wave is fascinating and very complex. I think a lot of the pros could not get a good handle on it, so don't feel left out. It always had a good MLC until now and that is often enough to keep tstorms going. The LLC forms due to very complex processes within the thunderstorm clusters near the center.
Oh, well, I'll have to finish later...

[SouthFloridawx]

I wouldn't rule out some type of Development in the BOC before moving inland, into Mexico.

[HURAKAN]

Just noticed that 99L is no more in NRL, nor the back-up site. It seems the NHC completely unplugged 99L.

[Sanibel]

99L is flattened on the top - so it is telling us it is riding under a guiding ridge. I agree with MGC. This will probably clip Honduras on a west track under that ridge. The forward speed is telling us it is being pushed by this ridge setting up in the Atlantic. The problem with 99L is the system is weaker than the surrounding synoptic. The surrounding synoptic therefore wins. On visible you can see the tropical flow bending NW in front of Yucatan. This could signal a slow down and turn before Yucatan. No way to tell until it happens.

Today the two ULL's, one in the Atlantic, one in the Caribbean, are folding and giving way as the Bermuda High finally sets up. You can see it on Caribbean WV loop.

[tailgater]

Thanks for your insight Phil, good stuff, but I guess I didn't explain myself very well. If there is no energy at the surface will this heat transfer still take place. The reason I ask is because IMHO(uneducated weather nerd) I didn't think that 99l ever had much at the surface, yet it was greatly effected by the diurnal Max each evening or was that happenstance, maybe cloud deck keeping the surface cooler until the sun broke through?
Just trying to learn something, please excuse all the grammer errors

Unfortunatley I won't be back here til later today. But quickly, there is always a LOT of energy over water that warm. Any mechanism that can lift it, such as an eastery ave in this case, will cause it to lift quite high into tall tstorms, provided other criteria are present.
This wave is fascinating and very complex. I think a lot of the pros could not get a good handle on it, so don't feel left out. It always had a good MLC until now and that is often enough to keep tstorms going. The LLC forms due to very complex processes within the thunderstorm clusters near the center.
Oh, well, I'll have to finish later...

Thanks again Phil, gotta run to work myself.

[skysummit]

Has anyone in the New Orleans watched the 12 noon edition of WWL news? Reports are that they mentioned recon is going in just to take measurements. Anyone else hear this?

[HURAKAN]

Has anyone in the New Orleans watched the 12 noon edition of WWL news? Reports are that they mentioned recon is going in just to take measurements. Anyone else hear this?

They just made that up.

ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY DAY OUTLOOK.....NEGATIVE.
3. REMARKS: INVESTS IN CARIBBEAN AND GULF OF MEXICO
FOR 03/1600Z AND 03/1800Z RESPECTIVELY BOTH
CANCELED BY NHC AT 03/1130Z.

RECON was cancelled at 730 AM EDT.

[tigergirl]

I watched WWL broadcast at noon and that is what the meterologist said.
Just wondering the same thing if they were going or not.
I am not making this up. Maybe the meterologist was mistaken.

[mgpetre]

Why is that convection in Honduras racing NNW? Anything to watch here? Just doesn't look like an overall westward motion is in store anymore. Thoughts?

[skysummit]

Why is that convection in Honduras racing NNW? Anything to watch here? Just doesn't look like an overall westward motion is in store anymore. Thoughts?

That convection is being enhanced by the ULL interacting with the wave. The wave axis is already west of Jamaica, but it is leaving a piece of energy behind. That comes to play into my theory I posted earlier. What if this convection persists as it moves to the WNW and NW toward a more favorable area in the Yucatan Channel?

[jasons2k]

99L behavior to date is just as I expected. I've been saying that development if any would not occur until 99L reached the W. Carb. Sea. 99L should start slowing down soon, at at time the chances improve slightly. It will likely hit land before it spins....MGC

Yep, I was saying 4 days ago not to expect anything until it reached the central/W. Caribbean and then reassess...and as of now not much to assess...

[vbhoutex]

99L behavior to date is just as I expected. I've been saying that development if any would not occur until 99L reached the W. Carb. Sea. 99L should start slowing down soon, at at time the chances improve slightly. It will likely hit land before it spins....MGC

Yep, I was saying 4 days ago not to expect anything until it reached the central/W. Caribbean and then reassess...and as of now not much to assess...

If 99L doesn't slam on the breaks soon it is even going to our race its' designation. I was figuring a reassessment in the W Carribean also, but if it doesn't slow down soon it will be in the pacific before I finish typing this thread. We have seen other fast moving invests come to fruition as TC's but I'm not to sure that 99L is going to be one of them. 2 days ago I thought it had a good core structure and that we would see something more by now. WRONG!!! I will still be watching, to say the least, but I definitely am not bullish on further development.

[jasons2k]

Yep, so far this is no Claudette