Invest 99L Thread #6

[wxwatcher91]

http://www.ssd.noaa.gov/PS/TROP/dvorak.html :

The Dvorak technique is a method using enhanced Infrared and/or visible satellite imagery to quantitatively estimate the intensity of a tropical system. Cloud patterns in satellite imagery normally show an indication of cyclogenesis before the storm reaches tropical storm intensity. Indications of continued development and/or weakening can also be found in the cloud features. Using these features, the pattern formed by the clouds of a tropical cyclone, expected systematic development, and a series of rules, an intensity analysis and forecast can be made. This information is then standardized into an intensity code.


Full Satellite Intensity Estimate Code:

EXAMPLE: Ttt/cc/Lvv/xxhrs
Where:
T - Tropical (ST is used for Sub-Tropical systems)
tt - Satellite Derived T-Number
cc - System Current Intensity T-Number
L - Past Change
D - Developing
W - Weakening
S - Little or No change (Same)
vv - Amount of Past change in T-Number
xx - Hours over which the change was observed


EXAMPLE: T3.5/3.5/D1.0/24hrs
Translation: The system appears on satellite imagery to be T-Number 3.5 storm. This value matches the Current intensity generating about 55 knots of sustained winds. The storm has developed a full T-Number in the past 24 hours increasing the wind speeds from 35 to 55 knots. The atmospheric pressure in the center of the storm has also lowered.

EXAMPLE: T4.5/5.5/W1.0/24hrs
Translation: The system appears on satellite imagery to be T-Number 4.5 storm. The Current intensity is still 5.5 and the system is still generating sustained winds of about 100 knots. As a forecast tool, the Dvorak technique is showing a weakening trend and the likelihood of a lowering CI within the next 24hours.
Our coordination call information only contains the satellite Derived T-Number and the Current intensity (Ttt/cc).

Dvorak Current Intensity Chart: http://www.ssd.noaa.gov/PS/TROP/CI-chart.html

[Sanibel]

I forget what year it was, but we had a big controversy with, I think it was Claudette, in this area a few years ago. Claudette was moving so fast across the caribbean that it didn't register a west wind, but did form further west. 99's convection is slightly weaker and different in shape, but it is similar. The wildcard is if 2007 is still hostile enough to take down such a system. But it seems a moot point if it enters a shear slackened GOM.

[Cookiely]

Hmm...this system is a rather curious creature...

Funny critter we got here...
Looks pretty

Pretty pretty wave how do you do???

Well anyway...what a funny critter

It does look pretty on visible. It looks like a comet. Little comet, I will still like you if you form into a depression or stay a simple wave.

[Tampa Bay Hurricane]

that Dvorak means its weakening. You only get a data T lower than the CI when it is weakening.

I know some really want a storm, but could we tone down some of the postings that this is developing when ALL meteorological data says it is not?

AMEN!!

Geeee...by the tone of this board it is obvious that some of you need to sit on Santa's lap and ask for a storm.

SANTA SANTA SANTA WHOOHOOO!!!!!!!!
Gimme a storm santa!!!!!!!!
Haha just kidding.
Sorry I couldn't resist.
I just want that friggin storm santa
gimme some Tropical Storm Dean!!!!
YEEEEEEEEEEEEEEEEHAWWWWWWWWWWW!!!!!!!


NOW THAT IS THE WISHCAST OF THE CENTURY!!!!
Or not.
Whatever.
Anyway, I think this will become a category 5 and eat our faces
off.
No just kidding. IM REALLY joking folks.

[astrosbaseball22]

lol

[fci]

that Dvorak means its weakening. You only get a data T lower than the CI when it is weakening.

I know some really want a storm, but could we tone down some of the postings that this is developing when ALL meteorological data says it is not?

AMEN!!

Geeee...by the tone of this board it is obvious that some of you need to sit on Santa's lap and ask for a storm.

Fox13:
That is HYSTERICAL!!!

[Brent]

I forget what year it was, but we had a big controversy with, I think it was Claudette, in this area a few years ago. Claudette was moving so fast across the caribbean that it didn't register a west wind, but did form further west. 99's convection is slightly weaker and different in shape, but it is similar. The wildcard is if 2007 is still hostile enough to take down such a system. But it seems a moot point if it enters a shear slackened GOM.

2003. I remember it well, the plane had been out there for many hours(and I think had like this one, been out the day before when it moved through the islands but found nothing) and finally was able to barely close off a circulation, and it was much the same deal for the 2 days after that. Immediately went to TS status and then became a hurricane briefly(post-analysis) and then weakened as fast as it strengthened(clipped the NE Yucatan as a 50-55 mph storm). Didn't really get going until the Gulf in the last day before landfall on the Middle TX coast.

[Extremeweatherguy]

http://www.nhc.noaa.gov/2003claudette.shtml?

The first part of this report does sound eerily similar to the current situation..

Claudette formed from a tropical wave that moved westward from the coast of Africa on 1 July. The wave first showed signs of convective organization on 6 July. By 7 July satellite imagery indicated sufficient organization to possibly classify the system as a tropical depression near the Windward Islands. However, the wave was moving westward at 20-25 kt at the time, and neither surface observations nor an investigation flight by the Air Force Reserve Hurricane Hunters indicated that the system had a closed circulation. The aircraft did report flight-level winds of tropical-storm force north of the vorticity maximum that passed near Barbados and St. Lucia.

The wave continued rapidly westward with a further increase in organization. Satellite intensity estimates suggested the system was near tropical storm strength by 1500 UTC 8 July. However, a second investigative flight could not find a closed center at that time. Finally, near 1800 UTC the plane found a small area of southwesterly winds and a pressure of 1006 mb. The wave became Tropical Storm Claudette at that time. The "best track" chart of the tropical cyclone's path is given in Figure 1, with the wind and pressure histories shown in Figure 2 and Figure 3, respectively. The best track positions and intensities are listed in Table

...Same speed, same "good looks", but no indication of a closed circulation from the recon missions.

[mgpetre]

I have a question about the trade winds acting on this thing right now, looks like some of the new convection is being blown west as it pops. Are the easterlies at a higher altitude in this area than they normally would be or is this just typical collapse / outflow I'm seeing?

[Buck]

Next time they reset the floater (which will have to be soon)... they should zoom it out a bit. It's funny that they reset it this morning and its already gonna need another adjustment soon! This thing is booking it... and getting larger. It is looking it's healthiest ever too. I think that if/when this does form a LLC, it will have TS strength winds already. This is a strange breed, that's for sure.

[wxman57]

It does look pretty on visible. It looks like a comet. Little comet, I will still like you if you form into a depression or stay a simple wave.

As long as it's moving as fast as a comet it's hard to develop an LLC. Watch for development as it approaches Honduras on Saturday. I'd give it a 40% shot at becoming a TS before it runs into the southern Yucatan. Maybe even a bit higher. But it has to slow down first.

[Sanibel]

I'd hold off on this for now. It looks like it is being dried out by subsidence and it's between two ULL's. One big one in the Atlantic and one over the west caribbean. All depends on tonight's burst.

[dwg71]

Next time they reset the floater (which will have to be soon)... they should zoom it out a bit. It's funny that they reset it this morning and its already gonna need another adjustment soon! This thing is booking it... and getting larger. It is looking it's healthiest ever too. I think that if/when this does form a LLC, it will have TS strength winds already. This is a strange breed, that's for sure.

Take a peek at this loop and see if you think its at its healthiest...

http://www.atmos.washington.edu/~ovens/ ... nhanced+12

[Ed Mahmoud]

IIRC there was a time when the H Hunters couldn't find a closed circulation on then Tropical Storm Andrew, but did find a ~50 knot wind North of the center, and NHC, suspecting it would restrengthen, made the decision not to downgrade it to a wave only to have to upgrade it back to a storm in 6 or 12 hours.


Think I read that in Bob Sheet's book.

[Ivanhater]

It does look pretty on visible. It looks like a comet. Little comet, I will still like you if you form into a depression or stay a simple wave.

As long as it's moving as fast as a comet it's hard to develop an LLC. Watch for development as it approaches Honduras on Saturday. I'd give it a 40% shot at becoming a TS before it runs into the southern Yucatan. Maybe even a bit higher. But it has to slow down first.

hehe..I was about to throw in the towel on this one...thanks for keeping hope alive!

[RL3AO]

If this storm had easterly shear of 25 kts or so, it would be in heaven.

[Buck]

Next time they reset the floater (which will have to be soon)... they should zoom it out a bit. It's funny that they reset it this morning and its already gonna need another adjustment soon! This thing is booking it... and getting larger. It is looking it's healthiest ever too. I think that if/when this does form a LLC, it will have TS strength winds already. This is a strange breed, that's for sure.

Take a peek at this loop and see if you think its at its healthiest...

http://www.atmos.washington.edu/~ovens/ ... nhanced+12

You're right... It was it's healthiest earlier today. But I'd say that the spin and the outflow look really good right now.

[dwg71]

^thats because you can see it now, absent blob of convection

[cheezyWXguy]

^thats because you can see it now, absent blob of convection

At this time of day, relative to the past few days, it looks its best...and is still firing little convection blobs as it has been all day, which is a first...and tonight it will refire, probably looking the same way it did this morning, tomorrow...its all part of the cycle

[Evil Jeremy]

its really starting to look nice on the visible!