ATL: ISAAC - Post-Tropical - Discussion

[Stormlover2012]

this thing looks horrible

[Bocadude85]

this thing looks horrible

Looks better now then it did this morning.

[SeminoleWind]

this thing looks horrible

Looks better now then it did this morning.

Agreed, slowly but surely coming together.

[Shuriken]

King Cap is definitely losing its grip; I predict we get a meatball tonight.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[SouthFLTropics]

Slightly off topic but I think we need a S2K dictionary and add some words to it that come along each year. In the past words such as Dynomat and Fist of Death would have made it in the dictionary. So far this year we have King Cap and Meatball. Priceless.

SFT

[Shuriken]

Slightly off topic but I think we need a S2K dictionary and add some words to it that come along each year. In the past words such as Dynomat and Fist of Death would have made it in the dictionary. So far this year we have King Cap and Meatball. Priceless.

SFT

That's actually a very good idea, SFl; I'll get on it in the wee hours (I'll post it in Talkin Tropics and link in my sig).

[ROCK]

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

one lone cold top and the remaining are warming. Probably due to loss of daytime heating.

the arc cloud in front thats been taking the SAL beating is having its tops blown off by westerly shear.....quite evident.

Low level convergence is lacking.....

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

[HURRICANELONNY]

94L might be sucking in some dry air. But if it finds some moisture it will be huge. Looking at the RGB loop it covers the size of Florida.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

['CaneFreak]

TD at 11 pm? :weenie

[islandgirl45]

For the benefit of some of us "non-mets," what is "King Cap?"

"King Cap" is what I label (it's not a met term) the upper-atmospheric condition governing whether or not a rising cumulonimbus in the tropics can make it all the way to the 200mb level (or roughly 70,000ft) in the hurricane belt. A storm able to do so has a "full pipe" to the very top of the troposphere, and can exhaust (i.e, "generate blow-off") extremely effectively -- nearly all of the rising column of air exhausts out the top of the convective stack rather than cyclically collapsing as is the case with normal pulsing cellular convection. This creates a suction draw at the surface, lowering pressures and tightening up low level circulations.

King Cap is either "ON" or "OFF" -- there's usually no middle ground. When it's "ON" (which is 99% of the time in the hurricane belt, as blow-off from the ITCZ and South American jungle convection create a semi-permanent Hadley Cell subsidence regime over the subtropics further north), you do not get hurricanes. When it's "OFF", even the junkiest systems can blow up despite otherwise lousy conditions such as dry air, shear and cool water temps.

In the context of a typical near-TD approaching the Caribbean, it's the difference between endless hours and days of sputtering along, and a sudden eruption heralding a steady intensification trend. On color infrared satellite, it'll be the appearance of a big red "meatball" of -75C tops.

Ah, so like a "cap" that inhibits convection from growing. And "meatballs" must be the same thing as "hot towers?"

[brunota2003]

Slightly off topic but I think we need a S2K dictionary and add some words to it that come along each year. In the past words such as Dynomat and Fist of Death would have made it in the dictionary. So far this year we have King Cap and Meatball. Priceless.

SFT

That's actually a very good idea, SFl; I'll get on it in the wee hours (I'll post it in Talkin Tropics and link in my sig).

For the record, there is a "dictionary" of sorts already in the S2K Tropical Reference Library forum (you can find it in the Talkin' Tropics forum, and I'll also link below to that forum). It is mostly acronyms, but same purpose.

viewforum.php?f=61

EDIT: Could someone pass along to the admins, can we also get a link posted to the forum here in the active forums, like how it is set up on the TT page? And perhaps a link to the forecasting contest forum? That might help gather steam for those two sections, as they would be more "visible" to people and such.

Sorry to hijack the thread.

[Shuriken]

Ah, so like a "cap" that inhibits convection from growing. And "meatballs" must be the same thing as "hot towers?"

Correct....although a "hot tower" refers to a CB while "meatball" is a color infrared depiction of anvil top blow-off.

I'm not a fan of "hot tower" usage, btw; "popping" CBs near the center of an LLC aren't always or even usually in a better moisture plume (i.e., higher atmospheric heat content); they're simply located in the area where the top of the atmosphere ("King Cap") is unraveling. IOW, newly rambunctious CBs are the result of a changing condition, not the cause of it.

[NDG]

What scares me of 94L is its circulation size & organization, when it gets into a more moist environment look out!
BTW, not liking the consistency of the GFS, and even worst is that its consistency proved right with Ernesto, but it could still be wrong.

[cycloneye]

Up to 90%

A WELL-DEFINED AREA OF LOW PRESSURE IS LOCATED ABOUT 800 MILES EAST
OF THE LESSER ANTILLES. WHILE SHOWERS AND THUNDERSTORMS REMAIN
SOMEWHAT LIMITED NEAR THE CENTER...ANY SIGNIFICANT INCREASE IN
THUNDERSTORM ACTIVITY COULD RESULT IN THE FORMATION OF A TROPICAL
DEPRESSION TONIGHT OR TOMORROW. THIS SYSTEM HAS A HIGH CHANCE...90
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES WESTWARD AT 20 TO 25 MPH. TROPICAL STORM WATCHES COULD
SOON BE REQUIRED FOR THE LEEWARD ISLANDS...AND INTERESTS IN THOSE
ISLANDS SHOULD MONITOR THE PROGRESS OF THIS DISTURBANCE.

[Bocadude85]

Convection is maintaining and even developing near the center


http://www.ssd.noaa.gov/PS/TROP/floaters/94L/flash-rb-short.html

[SouthDadeFish]

TRMM made a recent pass and actually revealed 94L has fairly impressive low level structure. Great banding. Once convection gets going it should take off. (Just my opinion)

[SeminoleWind]

Impressive circulation on that microwave imagery .

[tolakram]

Ah, so like a "cap" that inhibits convection from growing. And "meatballs" must be the same thing as "hot towers?"

Correct....although a "hot tower" refers to a CB while "meatball" is a color infrared depiction of anvil top blow-off.

I'm not a fan of "hot tower" usage, btw; "popping" CBs near the center of an LLC aren't always or even usually in a better moisture plume (i.e., higher atmospheric heat content); they're simply located in the area where the top of the atmosphere ("King Cap") is unraveling. IOW, newly rambunctious CBs are the result of a changing condition, not the cause of it.

I'm not understanding a lot of what you're saying, so let me respectfully ponder some of your theories.

Cap usually refers to a temperature or moisture difference that caps the atmosphere. In this case the dry air being entrained into the system might be considered the cap. it would be great if a pro could comment on this. Here is a nice overview of the way I understand the cap: http://www.stormtrack.org/library/forecast/cap.htm Is this what you see as the primary issue? If so, then it seems to me cap is another way to describe dry air entrainment, or a dry air layer near 94L.

As far as I understand it the height of storms in the tropics has everything to do with latitude rather than a special feature of tropical storms. http://www.windows2universe.org/earth/A ... itude.html

The term Hot Tower is described here: http://en.wikipedia.org/wiki/Hot_tower I think identifying hot towers near the center of circulation might indicate strengthening, but I'm not sure if it has any value in a developing storm like 94L. The only research I see if hot towers in eyewalls, not in developing systems. In any case the research points to hot towers providing a buffer to the dry air. Has there been any updated research on this?

Finally, numerous pro mets, but not the NHC that I can recall, have commented on the forward speed of the low level circulation being a hindrance to development. I don't think it was a coincidence that Ernesto finally developed after the forward speed slowed, but I can't find anything to either support or refute this.

I, personally, think it's terrific to theorize what might be happening, but I also think these theories need to be stated as such, in addition to the standard s2k disclaimer.

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[NDG]

No question about it that it has a well defined closed circulation, a good example was the westerly winds reported by the buoy earlier today as the COC passed to its north. Taken that the system is moving fairly fast above 20 mph, those reported westerly winds above 15 mph was impressive with a system that is/was lacking so much deep convection and moving so fast.

[TropicalAnalystwx13]

My forecast is unchanged from the past few nights.