ATL GUSTAV: Tropical Depression - Discussion

[superfly]

Regarding the dry air, the system is definitely trying to mix it with its latest burst. There's no question in my mind, however, that dry air (caused by the land interaction and especially the southerly shear) did a part in the sharp jump in the pressure, even if it's not reflected now as the center is moving northward.

We'll have to keep closely monitoring Gustav during the next few hours. The next Air Force Recon vortex message will be crucial to determine if Gustav is still weakening or a strengthening process is beginning.

There was no sharp jump in the pressure, if there was the winds wouldn't be only 5 knots lower.

There's nothing to support 115kts winds, I think NHC has it that high for continuity purposes. Recon shows about 100kts on their first pass.

[soonertwister]

Regarding the dry air, the system is definitely trying to mix it with its latest burst. There's no question in my mind, however, that dry air (caused by the land interaction and especially the southerly shear) did a part in the sharp jump in the pressure, even if it's not reflected now as the center is moving northward.

We'll have to keep closely monitoring Gustav during the next few hours. The next Air Force Recon vortex message will be crucial to determine if Gustav is still weakening or a strengthening process is beginning.

There was no sharp jump in the pressure, if there was the winds wouldn't be only 5 knots lower.

There's nothing to support 115kts winds, I think NHC has it that high for continuity purposes. Recon shows about 100kts on their first pass.

So you are saying that the NHC lied to us?

[ConvergenceZone]

Regarding the dry air, the system is definitely trying to mix it with its latest burst. There's no question in my mind, however, that dry air (caused by the land interaction and especially the southerly shear) did a part in the sharp jump in the pressure, even if it's not reflected now as the center is moving northward.

We'll have to keep closely monitoring Gustav during the next few hours. The next Air Force Recon vortex message will be crucial to determine if Gustav is still weakening or a strengthening process is beginning.

There was no sharp jump in the pressure, if there was the winds wouldn't be only 5 knots lower.

There's nothing to support 115kts winds, I think NHC has it that high for continuity purposes. Recon shows about 100kts on their first pass.

It is all irrelevant since it's expected to intensify anyway.

[Brent]

Eclipse over:

[AL Chili Pepper]

Eclipse is over. Can't wait to get another frame to see what's going on here.

http://www.ghcc.msfc.nasa.gov/GOES/goeseastconusir.html

[WxGuy1]

So you are saying that the NHC lied to us?

In a world in which politics and human psychology play absolutely no role in forecasts, I'd say that the NHC would never "lie". However, there are times when they may keep a storm artificially high -- such as time when a weakening storm is quickly expected to ramp back up (i.e. the weakening was temporary) and when such a storm is bearing down on a major population center. Saying that Gustav weakened from cat 5 to cat 3 may give people the wrong impression (regardless of the fact that it's expected to intensify again). I'd call it a "white lie". The data show what the data show.

[bahamaswx]

Major hurricane less than 48hrs from landfall. Why is it so quiet here?!

[Texashawk]

So you are saying that the NHC lied to us?

In a world in which politics and human psychology play absolutely no role in forecasts, I'd say that the NHC would never "lie". However, there are times when they may keep a storm artificially high -- such as time when a weakening storm is quickly expected to ramp back up (i.e. the weakening was temporary) and when such a storm is bearing down on a major population center. Saying that Gustav weakened from cat 5 to cat 3 may give people the wrong impression (regardless of the fact that it's expected to intensify again). I'd call it a "white lie". The data show what the data show.

Interesting observation, and makes quite a bit of sense to me.

[Hyperstorm]

Very disorganized cloud pattern after the eclipse. My original statements stand. This is decreasing in intensity at this time and my expectation is that the hurricane will be downgraded to a Category 3 at 5am.

As I said earlier, the outflow shield is rapidly approaching from the south...

Of course, EVERYONE in the northern Gulf Coast should be preparing for a stronger hurricane per official forecast, but my personal opinion is that this system will not be as strong as currently forecast to be at landfall.

[Texashawk]

Eclipse over:

Well... the CDO certainly seems to have slid WNW....

[shah8]

It's two A.M. after Cuba's worst landfalling hurricane since the 50's. I'd say everyone is tired

I certainly am.

[RL3AO]

Track and TCHP

[Wthrman13]

Very disorganized cloud pattern after the eclipse. My original statements stand. This is decreasing in intensity at this time and my expectation is that the hurricane will be downgraded to a Category 3 at 5am.

As I said earlier, the outflow shield is rapidly approaching from the south...

Actually, it looks like the outflow may have improved on the south side, which *could* signal a decrease in shear. Clearly, though, the inner core is a little disorganized at the moment.

[ConvergenceZone]

Very disorganized cloud pattern after the eclipse. My original statements stand. This is decreasing in intensity at this time and my expectation is that the hurricane will be downgraded to a Category 3 at 5am.

As I said earlier, the outflow shield is rapidly approaching from the south...

Of course, EVERYONE in the northern Gulf Coast should be preparing for a stronger hurricane per official forecast, but my personal opinion is that this system will not be as strong as currently forecast to be at landfall.

Well, if you are seeing it, then the NHC should absolutely positively mention it in their next discussion. If they don't mention it, then it's obviously nothing to worry about.......
It's moving into the loop current. It shouldn't be much longer. Plus it's moving along quite quickly at 14 mph.....

[bahamaswx]

Couldn't really have expected much improvement in the satellite signature during the eclipse with recon still reporting an open eyewall.

[Hyperstorm]

Very disorganized cloud pattern after the eclipse. My original statements stand. This is decreasing in intensity at this time and my expectation is that the hurricane will be downgraded to a Category 3 at 5am.

As I said earlier, the outflow shield is rapidly approaching from the south...

Actually, it looks like the outflow may have improved on the south side, which *could* signal a decrease in shear. Clearly, though, the inner core is a little disorganized at the moment.

It certainly "could", but I'll have to look at several images after the eclipse to assume that yet. Before the eclipse, however, there was clearly a line of mid-high level clouds south of the system heading north quickly. Usually, those undercut the highest cloud tops of a system and try to destroy their inner core.

For the sake of the people in the northern Gulf coast, I hope this system does not fully recover. My interpreration on upper wind patterns near time of landfall and oceanic heat content in the northern Gulf Coast, as well as recent history of landfalling hurricanes in that area, suggest that could be the case.

[Brent]

That's pretty ugly for a major hurricane I have to admit.

Looks sheared?

[superfly]

Couldn't really have expected much improvement in the satellite signature during the eclipse with recon still reporting an open eyewall.

The southern eyewall has been struggling ever since it left Cuba as I've said before. I don't know why so many people ignored radar and kept saying Gustav was deepening.

[CajunMama]

no way... and lili, went over the same area that isadore went over just a week or so earlier.. the water was churned up and cooler along the path... lets put all the peices together before we get carried away... no way the pressure is up that high... the reason the filled was due to land interaction... looking at the convection, it is already coming back..



Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

I don't know if Isidore had much to do with Lili's weakening. It would if those were over deep water like the Atlantic, but really shallow water should readjust more quickly.

I was curious as to why lili weakened and found this article by nasa

Satellites Unlock Hurricane Lili's Sudden Death

Using a fleet of NASA and other satellites as well as aircraft and other observations, scientists were able to unlock the secret of Hurricane Lili's unexpected, rapid weakening as she moved toward a Louisiana landfall in 2002. The data from several satellites helped researchers see dry air just above the ocean’s surface move into the lower levels of the storm. The dry air helped Hurricane Lili weaken quickly because a storm strengthens from warm, moist air, and weakens from dry air.

[CajunMama]

I was driving home from hattiesburg, ms tonight and was listening to wwl radio. They were saying that the eye was supposed to go directly over lake ponchartrain and there would be 17-20' storm surge and this would be like a storm that no one has ever seen before. Talk about instilling panic! I thought phew, lafayette may be lucky and my area may be lucky enough to be out of the picture. I got home and looked at all the info that we all use and couldn't believe they were telling people this.