ATL GUSTAV: Tropical Depression - Discussion

[KWT]

Yep sure does, also the eyewall now wrapped right around and the northern eyewall is bursting again with the eye clearing out very nicely, think that RI is going to continue whilst it has this presentation.

[Cyclenall]

On the cusp of the 2nd major hurricane of the season. Very impressive on that latest shot. I don't know what else to say other then this is going to be an incredible period for tracking(Hanna and Gustav).

[Matt-hurricanewatcher]

The reds have wraped all the way around. IF blacks start to wrap around this could jump to cat4 115-125 knots very very fast. I'm not kidding around.

[wxmann_91]

Some definite hot towers in there... -80 to -85C cloud tops (I think?) in the nrn eyewall on the latest (0815Z) image.

[KWT]

Yep and also 97l looking very likely to be a system soon as well...

As you say Cyclenall it does look like its ramping up towards major status, given the conditions its not going to take long with the type of deepening we are presently seeing.

[Brent]

[KWT]

That northern eyewall is looking really beefy now, the eye is looking elongated thanks to the explosive convection, hardly surprising given Dmax is probably fairly soon that convection is deepening.

[Hurricanewatcher2007]

Here You can clearly see where the eye is even more then the others!

[Texashawk]

I'm sure I'm just seeing things, but I swear in the last hour loop or so Gus's eye is moving almost due west...

[wxmann_91]

I'm sure I'm just seeing things, but I swear in the last hour loop or so Gus's eye is moving almost due west...

Perceived wobble due to cloud tops rolling around and about... Cuba radar asserts the NW motion is not halting.

[KWT]

Radar is so far away from the system it may not give a true motion but equally the IR may well give the illusion its moving west thanks to the explosive developments in the eyewall recently. Tough one to say.

[Cyclenall]

Some definite hot towers in there... -80 to -85C cloud tops (I think?) in the nrn eyewall on the latest (0815Z) image.

You mentioned "Hot Towers", are you familiar with that study that is being done on how these are observed just before rapid intensification? I saw a program that briefly talked about them and I had never heard of it before then. It's not confirmed scientifically yet.

What is the difference between a hot tower and a cold cloud top? Are they the same?

[KWT]

Yeah I remember hearing about them as well Cyclenall, I haven't really got a clue what the difference is myself but what I do know is that Gustav still looks increasingly good and I must assume pressure is dropping still.

[Matt-hurricanewatcher]

This run through I predict they will find 962 millibars, also 110 knot flight level winds in the northeast quad. This thing is bombing. That is what I think they will find.

[wxmann_91]

Some definite hot towers in there... -80 to -85C cloud tops (I think?) in the nrn eyewall on the latest (0815Z) image.

You mentioned "Hot Towers", are you familiar with that study that is being done on how these are observed just before rapid intensification? I saw a program that briefly talked about them and I had never heard of it before then. It's not confirmed scientifically yet.

What is the difference between a hot tower and a cold cloud top? Are they the same?

I don't put too much emphasis on hot towers WRT RI. Hot towers are thunderstorms that have tops that overshoot the tropopause. Although they are a sign that an eyewall is organizing and that vertical motion and instability is strong, they are not necessarily always a precursor to RI.

Cloud cloud tops are not necessarily an indicator hot towers, but here it is obvious a thunderstorm cell in the formative eyewall is overshooting the tropopause.

[KWT]

Possibly Matt though its hard to say, I think pressure is dropping faster then the winds are catching up though clearly with this presentation its only a matter of time before this is a major hurricane.

[Just Joshing You]

ESTIMATED MINIMUM CENTRAL PRESSURE 965 MB
EYE DIAMETER 30 NM
MAX SUSTAINED WINDS 95 KT WITH GUSTS TO 115 KT.
64 KT....... 50NE 25SE 0SW 30NW.
50 KT....... 75NE 60SE 30SW 60NW.
34 KT.......140NE 120SE 75SW 120NW.
12 FT SEAS..120NE 90SE 90SW 120NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 20.2N 81.3W AT 30/0900Z
AT 30/0600Z CENTER WAS LOCATED NEAR 19.7N 80.8W

FORECAST VALID 30/1800Z 21.2N 82.7W
MAX WIND 105 KT...GUSTS 130 KT.
64 KT... 50NE 35SE 30SW 35NW.
50 KT... 85NE 60SE 45SW 60NW.
34 KT...150NE 125SE 90SW 125NW.

FORECAST VALID 31/0600Z 22.9N 84.6W
MAX WIND 110 KT...GUSTS 135 KT.
64 KT... 50NE 40SE 35SW 40NW.
50 KT... 90NE 70SE 60SW 70NW.
34 KT...160NE 125SE 105SW 125NW.

FORECAST VALID 31/1800Z 24.6N 86.4W
MAX WIND 115 KT...GUSTS 140 KT.
64 KT... 50NE 40SE 35SW 40NW.
50 KT... 90NE 70SE 60SW 70NW.
34 KT...160NE 125SE 105SW 125NW.

FORECAST VALID 01/0600Z 26.5N 88.3W
MAX WIND 110 KT...GUSTS 135 KT.
50 KT... 90NE 75SE 60SW 75NW.
34 KT...160NE 125SE 105SW 125NW.

FORECAST VALID 02/0600Z 29.5N 91.5W...NEAR LOUISIANA COAST
MAX WIND 100 KT...GUSTS 120 KT.
50 KT... 75NE 75SE 60SW 75NW.
34 KT...120NE 120SE 100SW 120NW.

[Just Joshing You]

1 KT MORE FOR CAT 3? WOW

[Just Joshing You]

GUSTAV HAS BEEN RAPIDLY INTENSIFYING DURING THE OVERNIGHT HOURS.
SATELLITE IMAGES INDICATE THAT AN EYE IS BECOMING VISIBLE AND DEEP
CONVECTION SURROUNDING THE EYE IS NOW VERY INTENSE. THE CENTRAL
PRESSURE IS DOWN TO 965 MB...A DROP OF ABOUT 24 MB IN 24 HOURS. THE
MAXIMUM FLIGHT LEVEL WINDS REPORTED BY THE AIR FORCE CREW WERE 100
KT AROUND 6Z... CORRESPONDING TO ABOUT 90 KT AT THE SURFACE.
HOWEVER THE SATELLITE PRESENTATION HAS CONTINUED TO IMPROVE...THUS
THE INITIAL INTENSITY IS INCREASED CONSERVATIVELY TO 95 KT.
OBJECTIVE DVORAK T-NUMBERS ARE MUCH HIGHER AND THE NEXT AIRCRAFT
PASS THROUGH GUSTAV COULD FIND A MAJOR HURRICANE.

FURTHER INTENSIFICATION IS EXPECTED FOR THE NEXT DAY OR SO WHILE THE
SYSTEM TRAVERSES THE EXTREMELY WARM AND DEEP WATERS OF THE
NORTHWESTERN CARIBBEAN SEA AND SOUTHERN GULF OF MEXICO.
HOWEVER...BY 48 HOURS...ALMOST ALL OF THE GLOBAL MODELS SHOW AN
INCREASE IN VERTICAL WIND SHEAR NEAR GUSTAV. IN ADDITION...SINCE
THE LOOP CURRENT IS SOUTH OF ITS TYPICAL LOCATION...THE HURRICANE
WILL BE MOVING OVER WATERS THAT ARE NOT NEARLY AS CONDUCIVE FOR
STRENGTHENING AS THEY COULD BE. THESE TWO FACTORS WILL HOPEFULLY
WEAKEN THE STORM PRIOR TO U.S. LANDFALL. HOWEVER...GUSTAV IS
EXPECTED TO BE A LARGE AND DANGEROUS HURRICANE AND THE NHC FORECAST
CONTINUES TO SHOW GUSTAV AS A MAJOR HURRICANE AT LANDFALL.

THE INITIAL MOTION ESTIMATE IS 310/10. A MID-LEVEL RIDGE FROM THE
WESTERN ATLANTIC TO NORTHERN FLORIDA IS EXPECTED TO CONTINUE MOVING
THE HURRICANE TO THE NORTHWEST FOR THE NEXT COUPLE OF DAYS.
THEREAFTER...A RIDGE OVER THE OHIO VALLEY SHOULD CAUSE A GRADUAL
LEFTWARD BEND IN THE TRACK AS GUSTAV APPROACHES THE NORTHERN GULF
COAST. MOST OF THE GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO
EXCEPT FOR THE UKMET/HWRF...WHICH TURN THE SYSTEM JUST OFFSHORE.
THESE TWO MODELS ARE SLOWER AND TO THE LEFT OF MOST OF THE TRACK
GUIDANCE...WHICH ALLOWS A RIDGE TO FORM OVER TEXAS TO TURN THE
STORM. THE OFFICIAL FORECAST WILL STAY WITH THE MAJORITY OF THE
GUIDANCE AND IS BASICALLY AN UPDATE TO THE PREVIOUS PACKAGE. GUSTAV
WILL LIKELY SLOW DOWN SIGNIFICANTLY IN THE LONGER-TERM...WHICH
COULD CAUSE A CONSIDERABLE FLOODING THREAT OVER LOUISIANA OR TEXAS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 30/0900Z 20.2N 81.3W 95 KT
12HR VT 30/1800Z 21.2N 82.7W 105 KT
24HR VT 31/0600Z 22.9N 84.6W 110 KT
36HR VT 31/1800Z 24.6N 86.4W 115 KT
48HR VT 01/0600Z 26.5N 88.3W 110 KT
72HR VT 02/0600Z 29.5N 91.5W 100 KT...NEAR LOUISIANA COAST
96HR VT 03/0600Z 30.5N 93.0W 70 KT...INLAND
120HR VT 04/0600Z 31.0N 94.0W 35 KT...INLAND

[KWT]

Wow 95kts sustained now, higher then I expected it to be actually, but I does make sense given the structure and what recon has found.

Just a heartbeat away from its destiny of being a major hurricane and cat-4 isn't out of the question now it seems if it holds this presentation upto landfall.