Invest 96L=Tropical Wave in Southern Caribbean

['CaneFreak]

Why is it that everyone is so concerned with the convection? That is all I have heard the last several days...its ALL ABOUT THE DRY AIR...WHO CARES ABOUT THE CONVECTION? I am more worried about whether the freaking LLC makes it as far west as the eastern or central Caribbean without falling off of the face of the earth. That is what is concerning me right now...

Convection is vital to the survival of the disturbance. Convection (rising air near the center) acts to increase inflow in toward the center, resulting in increased lift, lower pressure, and more convection. Without any convection to create inflow, the low gradually spins down and dies.

Well, of course, I mean..convection is going to pulsate, cloud tops will cool at night (typically) and warm during the day as this is a tropical wave and this is what they do. But, my point is, since the convection will probably pulsate over the next several days, this disturbance's circulation will more than likely make it to the carribean sea area. So why is everyone so concerned with the convection at the present moment? I hope this clears up what I was trying to say..if not I will try to reclarify, but anywho...yeah..

[Trader Ron]

Like I said yesterday. Dry Air will lead to it's demise.

Happy 4th everyone.

[harmclan]

Well, of course, I mean..convection is going to pulsate, cloud tops will cool at night (typically) and warm during the day as this is a tropical wave and this is what they do. But, my point is, since the convection will probably pulsate over the next several days, this disturbance's circulation will more than likely make it to the carribean sea area. So why is everyone so concerned with the convection at the present moment? I hope this clears up what I was trying to say..if not I will try to reclarify, but anywho...yeah..

I understand exactly what you're saying. People are passing judgments on 96L based primarily on the amount/strength of the convection associated with it. When the convection dies down during the day, people write 96L off only to see convection increase during the night. As someone stated last night, there was a reason NHC stuck to forecasting the path and not intensification until 1990

['CaneFreak]

Exactly...I mean look at the disturbances of the past....even better...look at Ivan...geez..that was absolutely crazy...it held together for all that time without whole lot of convection around it...and in the face of many obstacles...still became ONE OF THE LONGEST tracking systems in recorded history. Please dont write this one off until it is dead and the circulation stops circulating.

[cheezyWXguy]

As of now it looks like it completely detached from the ITCZ at the moment...I maybe wrong but thats what it looks like to me

The ITCZ detached from the east side over 24 hours ago, detachment from the west side became evident late yesterday.

http://ustropics.ulmb.com

As of early this morning it didnt look like it had disconnected yet, and now im sure of it being disconnected

[Cyclone1]

Well, now that it's off the ITCZ, all it need is convection. That should come into play tonight. It's a fighter.

[philnyc]

This storm continues to behave pretty much as expected. It's ingesting tons of dry air right now, and that is why the convection can't get going. The shear is almost non-existent, so it's not being sheared:

]

However, there is enough moisture to its south and immediate west that you'll see occasional flareups of convection on the south semi-circle for the next day or so. This morning's 12Z run of the GFS global model shows that by Friday morning it should start encountering a less dry environment:



If the LLC holds together until then (and it sure looks like it will), look out Loretta...

[wxman57]

Careful with that shear map, philnyc, it's a shear tendency map, not a map of current wind shear. It's only indicating that the shear has increased by 5-10 kts in the past 24 hours, not that shear is 5-10 kts in advance of the disturbance. As an example, there could be 50 kts of shear which increases to 55 kts in 24hrs, and the tendency would be only +5 kts.

This storm continues to behave pretty much as expected. It's ingesting tons of dry air right now, and that is why the convection can't get going. The shear is almost non-existent, so it's not being sheared:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.GIF

However, there is enough moisture to its south and immediate west that you'll see occasional flareups of convection on the south semi-circle for the next day or so. This morning's 12Z run of the GFS global model shows that by Friday morning it should start encountering a less dry environment:

http://i189.photobucket.com/albums/z174/philnyc_2007/2007-07-0612Zforecast700mbRHinit07-.gif

If the LLC holds together until then (and it sure looks like it will), look out Loretta...

[philnyc]

Careful with that shear map, philnyc, it's a shear tendency map, not a map of current wind shear. It's only indicating that the shear has increased by 5-10 kts in the past 24 hours, not that shear is 5-10 kts in advance of the disturbance. As an example, there could be 50 kts of shear which increases to 55 kts in 24hrs, and the tendency would be only +5 kts.

Whoops! Sorry. You are 100% correct. I of course know the difference (been looking at CIMSS for years) but I got over-involved with copying pictures back and forth (such a pain). I'll edit that post, and here's the current shear, quite low as you can see:



Thanks for pointing that out.

[wxman57]

I calculated a forward speed of just over 13 kts to the west today, so the relative shear (as opposed to the shear indicated on that map may actually be higher). Wind shear is actually forecast to be in the 15-20kt range between 50W and the Caribbean in 48 hours, and increasing westward into the Caribbean and beyond. However, the dry air and lack of convergence (due to a lack of convection near the center) are the real culprits in 96L's demise. I've rarely, if ever, seen a disturbance survive in such an environment after looking this poorly. I feel very confident that this disturbance will not be a significant problem to the islands of the eastern Caribbean on Sunday as it passes between Trinidad and St. Lucia, probably as a weak tropical wave.

Here's a good map to look at - the lower-level convergence. Without lower-level convergence, it's hard to build squalls. No convection, no inflow, no deepening low, resulting in a gradual spin-down of LLC, etc:

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8conv.html

Well, the rain has stopped here in Houston and the street (and bike trail) is drying off. Time to get ready to head out for a nice evening ride and fireworks show with the wife in a few hours.

[cpdaman]

ahh the relative shear

and btw the SW Mid level shear had increased (12-14mph) and the direction of shear effecting the system CHANGED (from blowing with it to into it over the last 12hours (as it crossed 42W) AND BLEW directly INTO the LLC . latest CIMSS shear maps show mid level shear in the face of the storm has abated to less than 10 mph)

long term shear forecasts which can be tricky do not bode well not to mention the dry air around this thing (although i assume the shear is easterly wind shear?)

p.s anyone notice how loud the thunder was in SE florida at 430 talk about fireworks!

[philnyc]

I calculated a forward speed of just over 13 kts to the west today, so the relative shear (as opposed to the shear indicated on that map may actually be higher). Wind shear is actually forecast to be in the 15-20kt range between 50W and the Caribbean in 48 hours, and increasing westward into the Caribbean and beyond. However, the dry air and lack of convergence (due to a lack of convection near the center) are the real culprits in 96L's demise. I've rarely, if ever, seen a disturbance survive in such an environment after looking this poorly. I feel very confident that this disturbance will not be a significant problem to the islands of the eastern Caribbean on Sunday as it passes between Trinidad and St. Lucia, probably as a weak tropical wave.

Well, the rain has stopped here in Houston and the street (and bike trail) is drying off. Time to get ready to head out for a nice evening ride and fireworks show with the wife in a few hours.

Good points, wxman57, especially that one looking this bad rarely survives. Enjoy your ride and the fireworks. Happy 4th!

[cycloneye]

ABNT20 KNHC 042103
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 PM EDT WED JUL 4 2007

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A WELL-DEFINED LOW PRESSURE AREA OVER THE CENTRAL ATLANTIC OCEAN IS
LOCATED ABOUT 1100 MILES EAST OF THE SOUTHERN WINDWARD ISLANDS
MOVING WESTWARD AT 10 TO 15 MPH. ASSOCIATED SHOWER AND THUNDERSTORM
ACTIVITY HAS DISSIPATED THIS EVENING. HOWEVER...THIS SYSTEM STILL
HAS SOME POTENTIAL FOR TROPICAL CYCLONE FORMATION DURING THE NEXT
DAY OR SO BEFORE UPPER-LEVEL WINDS BECOME LESS FAVORABLE FOR
DEVELOPMENT.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER RHOME

[x-y-no]

Well, the rain has stopped here in Houston and the street (and bike trail) is drying off. Time to get ready to head out for a nice evening ride and fireworks show with the wife in a few hours.

Same here. Gonna ride my bike down to Hollywood Beach, grab some food and watch the fireworks.

[Toadstool]

p.s anyone notice how loud the thunder was in SE florida at 430 talk about fireworks!

Yes! You can't ignore thunder that LOUD! And constant! Hopefully it will clear up before the man-made fireworks tonight!

Happy 4th!

[O Town]

Wow, just got home from a bbq and that thing (96L) looks soooooo sad. Boo hoo LOL
Hope everyone has/had a nice 4th. Happy Birthday U.S.A.!!!

[windstorm99]

Wow i posted the 5:30pm a few minutes ago and it was erased....Not sure the reason for that.

[cycloneye]

For the members who live in the Eastern Caribbean islands I can say that we are in good shape in terms of not having to deal with a Cyclone in our vicinity.Anyway,let's keep watcing the wave in terms of how much rain and some squalls it may bring to some of the islands starting on Sunday.However,the wave may be more weaker as it moves thru the islands and if that is the case,even some squalls with be absent.So msbee,dont change your travel plans and enjoy your trip.

[cycloneye]

Wow i posted the 5:30pm a few minutes ago and it was erased....Not sure the reason for that.

Aparently,you didn't noticed that it was already posted at 5:11 PM.

[windstorm99]

Wow i posted the 5:30pm a few minutes ago and it was erased....Not sure the reason for that.

Aparently,you didn't noticed that it was already posted at 5:11 PM.

Very true...Sorry about that.