ATL GUSTAV: Tropical Depression - Discussion

[Matt-hurricanewatcher]

This system looks like a 70 knot cat1 to me based on IR. In fact, I doubt it would even be a cane if this was at 15 north/30 west. Why you ask, microwave data would only show that it has part of a eye, in which would tell the nhc that this should be at least 50-55 knots. In which case the nhc would likely make it around that. They would be forecasting this to become one if the environment was favorable enough.

Do you agree or disagree with this?

[physicx07]

Wow, at this moment there appear to be 8 or 9 radar detected tornadoes mostly in the FL panhandle and Alabama, and one in Louisiana.

Also on radar, looks like it's still a tad offshore. I know this is looking a little higher up, but if the system is stacked like it should be for a cat 2, then it shouldn't be a big issue.

[Chacor]

This system looks like a 70 knot cat1 to me based on IR. In fact, I doubt it would even be a cane if this was at 15 north/30 west. Why you ask, microwave data would only show that it has part of a eye, in which would tell the nhc that this should be at least 50-55 knots. In which case the nhc would likely make it around that. They would be forecasting this to become one if the environment was favorable enough.

Do you agree or disagree with this?

Pressures from recon support a storm far stronger than 70 kt.

[KWT]

Yep winds and presentation far better then a 70kts hurricane as well I agree Chacor, looks don' matter quite so much with a weakening hurricane simply because it takes a while for the winds to ease down until the system is overland.

[Matt-hurricanewatcher]

This system looks like a 70 knot cat1 to me based on IR. In fact, I doubt it would even be a cane if this was at 15 north/30 west. Why you ask, microwave data would only show that it has part of a eye, in which would tell the nhc that this should be at least 50-55 knots. In which case the nhc would likely make it around that. They would be forecasting this to become one if the environment was favorable enough.

Do you agree or disagree with this?

Pressures from recon support a storm far stronger than 70 kt.

I'm saying if it was not for the recon, and this storm was out in the middle of the Atlatnic. This goes to show that looks are not everything.

[USTropics]

Yep sure looks like it on radar now, should get offical word through on a landfall pretty soon I'd have thought.

I believe it is an official landfall when the entire eye has come ashore. Looking at KLIX radar, the northern portion is just now making landfall.

[KWT]

No Matt Dvorak numbers also support way higher then 70kts right now as well.

The other threat further out from the inner core in the more outer bands has to be tornadoes, its producing a fair few and these are rain wrapped which makes them tough to see.

ustropics, yeah te northern part of the eye onshore now but the center isn't just there yet.

[PhillyWX]

http://philadelphiaweather.blogspot.com ... m-new.html

Some updated images from LA...

[HURAKAN]

Landfall.

[physicx07]

Landfall.

Radar at 1242Z from LIX suggests not yet.

[O Town]

Looks like he jogs west before N eyewall makes lanfall. Like following the shoreline.

[Chacor]

Remember it's not always the centre of the eye — it has to be the centre of circulation, which isn't necessarily stacked with the centre of the eye, that crosses land to count as landfall.

[Matt-hurricanewatcher]

This thing appears to be going west-northwest or even west. I would say 285-295 degree's right now...If it can make it another .5 of a degree westward it will earn its self another 3-4 hours over water as the shoreline slope northward after that.

[Chacor]

Remember it's not always the centre of the eye — it has to be the centre of circulation, which isn't necessarily stacked with the centre of the eye, that crosses land to count as landfall.

Just to prove my point, this came out at the right time...

URNT12 KNHC 011247
VORTEX DATA MESSAGE AL072008
A. 01/12:30:20Z
B. 28 deg 49 min N
090 deg 24 min W
C. 700 mb 2734 m
D. 74 kt
E. 272 deg 17 nm
F. 002 deg 081 kt
G. 271 deg 044 nm
H. 957 mb
I. NA C/ 3042 m
J. 16 C/ 3044 m
K. 14 C/ NA
L. CLOSED WALL
M. C30
N. 12345/7
O. 0.02 / 2 nm
P. AF307 2807A GUSTAV OB 12
MAX FL WIND 91 KT NW QUAD 11:45:00 Z
MAX OUTBOUND FL WIND 90 KT E QUAD 12:36:30Z
MULTIPLE SMALL BREAKS IN WALL CLOUD
UNABLE TO FIX SFC CNTR

The IR/visible eye doesn't always stack with the surface centre.

[KWT]

Yep thats a good point Chacor its the center of circulation that needs to cross and thus far radar shows the center of cirrculation is still over water, though the northern part of the eye has been brushing the shore, seems to be on a mainly WNW motion now.

[physicx07]

Remember it's not always the centre of the eye — it has to be the centre of circulation, which isn't necessarily stacked with the centre of the eye, that crosses land to count as landfall.

Just to prove my point, this came out at the right time...

URNT12 KNHC 011247
VORTEX DATA MESSAGE AL072008
A. 01/12:30:20Z
B. 28 deg 49 min N
090 deg 24 min W
C. 700 mb 2734 m
D. 74 kt
E. 272 deg 17 nm
F. 002 deg 081 kt
G. 271 deg 044 nm
H. 957 mb
I. NA C/ 3042 m
J. 16 C/ 3044 m
K. 14 C/ NA
L. CLOSED WALL
M. C30
N. 12345/7
O. 0.02 / 2 nm
P. AF307 2807A GUSTAV OB 12
MAX FL WIND 91 KT NW QUAD 11:45:00 Z
MAX OUTBOUND FL WIND 90 KT E QUAD 12:36:30Z
MULTIPLE SMALL BREAKS IN WALL CLOUD
UNABLE TO FIX SFC CNTR

The IR/visible eye doesn't always stack with the surface centre.

I don't think you can reliably see the eye in IR. It's been partially to mostly filled all day. So if you can't locate it at the surface, however they tried, then what else can you use but radar?

[Chacor]

Remember it's not always the centre of the eye — it has to be the centre of circulation, which isn't necessarily stacked with the centre of the eye, that crosses land to count as landfall.

Just to prove my point, this came out at the right time...

URNT12 KNHC 011247
VORTEX DATA MESSAGE AL072008
A. 01/12:30:20Z
B. 28 deg 49 min N
090 deg 24 min W
C. 700 mb 2734 m
D. 74 kt
E. 272 deg 17 nm
F. 002 deg 081 kt
G. 271 deg 044 nm
H. 957 mb
I. NA C/ 3042 m
J. 16 C/ 3044 m
K. 14 C/ NA
L. CLOSED WALL
M. C30
N. 12345/7
O. 0.02 / 2 nm
P. AF307 2807A GUSTAV OB 12
MAX FL WIND 91 KT NW QUAD 11:45:00 Z
MAX OUTBOUND FL WIND 90 KT E QUAD 12:36:30Z
MULTIPLE SMALL BREAKS IN WALL CLOUD
UNABLE TO FIX SFC CNTR

The IR/visible eye doesn't always stack with the surface centre.

I don't think you can reliably see the eye in IR. It's been partially to mostly filled all day. So if you can't locate it at the surface, however they tried, then what else can you use but radar?

Well, they found an eye (L. CLOSED WALL; M. C30) or at least an eyewall, but it's apparently not the centre.

[Mattie]

Just hear that the eyewall is regenerating and hugging the coast - comments?

[CrazyC83]

I'd say the landfall intensity will be 95 kt.

[BigB0882]

Waiting here in Baton Rouge, lights flickered but came back, thank goodness. Looks like some of the heavier rain about to move in but we have had hardly anything yet in the way of rain or wind. I guess it will come later but it is looking like we dodged a bullet. I am not sure this is at all a 115 mph hurricane right now.