INVEST 99L near Leewards,comments,sat pics,etc #4

[Air Force Met]

http://www.ssd.noaa.gov/goes/flt/t1/avn.jpg

Any chance that the LLC could reform under the deeper convection.

No. That only works when the systems are stationary or moving very slowly. What would probably happen would be the current LLC would be drawn under the convection by slowing down (the pressure gradient would lower under the convection...and it would be pulled in).

However, in situations like this, the best chance is for new convection to form over the center.

[NDG]

Until a west wind is reported at the surface by either recon, a ship or a island observation, we can only conclude that there is not a closed surface low. Sure, there is a circulation but the strongest of it appears above the surface. I base this on observing the low level cloud motion in the last visible frames of the visible loop. Convection is absent in all but the NE quads. I don't see the NHC upgrading this to a depression tonight unless of course there is an explosion of convection near the circulation center. I've seen many systems that have great satellite presentations but lack a surface circulation. I must admit that yesterday at this time I was on the verge of writing off this disturbance, just goes to show that trying to figure out tropical weather is more than challenging.....MGC

A west wind was already reported by a buoy as the center passed by real close to it.

[cheezyWXguy]

is the ULL over the bahamas weakening?

[NDG]

is the ULL over the bahamas weakening?

No, but is forecasted to start moving westward as a ridge builds near the US east coast.

[cheezyWXguy]

would that mean more favorable conditions for the storm when it approaches the area?

[Matt-hurricanewatcher]

I see the LLC near where wxman57 around 16.5 north/58-58.5 west. Moving westward now. The convection is starting to spread over it so its harder to spot. But you see the flow at the lower levels moving in from the south...In a northwestly around the northwestern side. This is closed in slowly becoming better organized. But you can also still see that the high clouds are blowing southeastward as the northwest shear is trying to push the convection away.

Even with the shear this is becoming more organized. Its looking very likely this will be a depression very soon. As another pro said that this thing could get between the tutt's. In which would weaken the shear...In which could be starting with the convection trying to push over the LLC.

[NDG]

would that mean more favorable conditions for the storm when it approaches the area?

Yes, but it will be a very tight area.

[Bailey1777]

wxman57 I have been following these threads for the past 3 days and you and AFM seem to be the most knowledgable to me. You have been great at what is going on and obviously not impressed. I ask both you and AFM what do you see happening with this system between now and 72hrs?

[Bailey1777]

Also what determines how large of a circulation a system will have?

[fci]

TABB has the "Possible Tropical Cyclone Formation 36 hours posted for 99L.

http://www.nhc.noaa.gov/tafb_latest/dan ... testBW.gif

[Air Force Met]

wxman57 I have been following these threads for the past 3 days and you and AFM seem to be the most knowledgable to me. You have been great at what is going on and obviously not impressed. I ask both you and AFM what do you see happening with this system between now and 72hrs?

Thanks for the complement...but I'll quote Avila (from an NHC conference call once):

"Only God know what hurricane does."

And you know what? He's right. All this "Write it off...its done...and this "It's gonna be a ___" is a bunch of bunk, written by people who are all hat and no cattle....cause my 19+ years in weather have taught me: Ain't nothin' for sure!

The only thing sure about forecasting the weather is the sunrise and sunset forecast...and given the chance...we mess that up too.

[Ola]

wxman57 I have been following these threads for the past 3 days and you and AFM seem to be the most knowledgable to me. You have been great at what is going on and obviously not impressed. I ask both you and AFM what do you see happening with this system between now and 72hrs?

Thanks for the complement...but I'll quote Avila (from an NHC conference call once):

"Only God know what hurricane does."

And you know what? He's right. All this "Write it off...its done...and this "It's gonna be a ___" is a bunch of bunk, written by people who are all hat and no cattle....cause my 19+ years in weather have taught me: Ain't nothin' for sure!

The only thing sure about forecasting the weather is the sunrise and sunset forecast...and given the chance...we mess that up too.

And the tides

[wxmann_91]

The only thing sure about forecasting the weather

...is that there is always the possibility of something going wrong.

[abajan]

The influence of 99L on our winds can clearly be seen:
http://weather.noaa.gov/weather/current/TBPB.html

I doubt it'll be very long before we see a TD coming out of this.

[caribepr]

Well, I am leaving for Montreal on Wednesday, so I've been following this a bit closely without saying much. Tonight, I am prepped at home. I gave my friend a huge rope to tie the cart to the bridge as it's in a sort of strange windless corner (not really windless but...pretty protected).
If that doesn't work, things will be over the top anyway so it won't matter much. I've done all I can do, and hope I come home to all being same old same old.
The next wave won't be around until I get back (unless it moves faster, as it could...oh well) so I'll deal with one wave at a time, thank you!
Air Force Met...thank you so much for your last post, because that is so much how I (and so many others I know) feel. Ends up being, prepare for the worst, hope for the best (and hang together with your loved ones could be added).
I'm going to have a wonderful time away, worry somewhat and not watch the weather, as it looks so horrible on radar and doesn't mean it is that way at ALL. Ok, I will watch, but as my 93 year old aunt (who I'm going to be with) will worry too much if I act worried, I won't watch much! What will be, will be.

[btangy]

Environmental conditions favor this system not to develop in the near term.

Here's the AMSR-E overpass at 17Z showing the precipitable water (which is the column integrated water vapor) ahead of 99L:
http://www.nrlmry.navy.mil/tcdat/tc06/A ... W.62pc.jpg

Notice the aquas and greens ahead of the system indicating precip. water values around 30-40mm (1.2-1.5in), which is quite low. The precip. water near the disturbance is contaminated by convection, so to get a sense of the environmental values, you have to look around the periphery of the disturbance.

The 12Z sounding from Guadeloupe confirms this:
http://weather.uwyo.edu/upperair/images ... .skewt.gif

For those unfamiliar with skew-T diagrams with right line is the temperautre profile and the left line is the moisture (specific humidity) profile. Roughly speaking, the separation between the two lines is a measure of the relative humidity. Above 800mb, the air is really dry which confirms the low preciptable water values as measured by the AMSR-E satellite.

The sounding also has E/NE winds 15-25knots which is helping to push the dry air into the system. Hence, this is why you're seeing convection flare up but die out quickly because the dry air in the mid-levels is inducing downdrafts (due to rain evaporating in the dry air, thereby cooling the air causing it to be denser and, hence, causing it to sink producing these outflow boundaries that you see on visible satellite imagery). Convection cannot maintain itself for the length of time necessary for the circulation to spin up.

Here is the CIMSS upper level cloud analyzed winds from 18Z:
http://cimss.ssec.wisc.edu/tropic/real- ... wvir-1.GIF

Besides the shear, also note that near the disturbance itself, there is some nice divergence with the wind barbs oriented opposite to one another to the SW and NE of the disturbance. This is a signature of a deformation zone and could be responsible for dynamically forcing the current convection over the system and the organization observed today.

Once this dynamical forcing dissappears and with the environmental conditions pretty unfavorable for further development, the system should decay.

Even if it does get the TD upgrade, I wouldn't expect much if any strengthening.

[Windtalker1]

Environmental conditions favor this system not to develop in the near term.

Here's the AMSR-E overpass at 17Z showing the precipitable water (which is the column integrated water vapor) ahead of 99L:
http://www.nrlmry.navy.mil/tcdat/tc06/A ... W.62pc.jpg

Notice the aquas and greens ahead of the system indicating precip. water values around 30-40mm (1.2-1.5in), which is quite low. The precip. water near the disturbance is contaminated by convection, so to get a sense of the environmental values, you have to look around the periphery of the disturbance.

The 12Z sounding from Guadeloupe confirms this:
http://weather.uwyo.edu/upperair/images ... .skewt.gif

For those unfamiliar with skew-T diagrams with right line is the temperautre profile and the left line is the moisture (specific humidity) profile. Roughly speaking, the separation between the two lines is a measure of the relative humidity. Above 800mb, the air is really dry which confirms the low preciptable water values as measured by the AMSR-E satellite.

The sounding also has E/NE winds 15-25knots which is helping to push the dry air into the system. Hence, this is why you're seeing convection flare up but die out quickly because the dry air in the mid-levels is inducing downdrafts (due to rain evaporating in the dry air, thereby cooling the air causing it to be denser and, hence, causing it to sink producing these outflow boundaries that you see on visible satellite imagery). Convection cannot maintain itself for the length of time necessary for the circulation to spin up.

Here is the CIMSS upper level cloud analyzed winds from 18Z:
http://cimss.ssec.wisc.edu/tropic/real- ... wvir-1.GIF

Besides the shear, also note that near the disturbance itself, there is some nice divergence with the wind barbs oriented opposite to one another to the SW and NE of the disturbance. This is a signature of a deformation zone and could be responsible for dynamically forcing the current convection over the system and the organization observed today.

Once this dynamical forcing dissappears and with the environmental conditions pretty unfavorable for further development, the system should decay. I would be surprised to see 99L organize any further.

Be prepared to be surprised.

[Matt-hurricanewatcher]

Its already very close to a depression. I would not be suprized if it was already one. But thats my option. In most likely if it keeps up one by the nhc by 11am tomarrow.

[Stephanie]

Well, I am leaving for Montreal on Wednesday, so I've been following this a bit closely without saying much. Tonight, I am prepped at home. I gave my friend a huge rope to tie the cart to the bridge as it's in a sort of strange windless corner (not really windless but...pretty protected).
If that doesn't work, things will be over the top anyway so it won't matter much. I've done all I can do, and hope I come home to all being same old same old.
The next wave won't be around until I get back (unless it moves faster, as it could...oh well) so I'll deal with one wave at a time, thank you!
Air Force Met...thank you so much for your last post, because that is so much how I (and so many others I know) feel. Ends up being, prepare for the worst, hope for the best (and hang together with your loved ones could be added).
I'm going to have a wonderful time away, worry somewhat and not watch the weather, as it looks so horrible on radar and doesn't mean it is that way at ALL. Ok, I will watch, but as my 93 year old aunt (who I'm going to be with) will worry too much if I act worried, I won't watch much! What will be, will be.

I hope everything will be just as you left it when you get back. Have a safe trip!

[cycloneye]

31/2345 UTC 15.9N 57.8W T2.0/2.0 99L -- Atlantic Ocean


TD now with those numbers?