ATL: ISAAC - Post-Tropical - Discussion

[SeminoleWind]

Isn't the rule if your in the 5 day cone at day 5 your not going to get hit.

Thats what i have always heard too, i will give it another day or so before i get to concerned

[Riptide]

Isn't the rule if your in the 5 day cone at day 5 your not going to get hit.

Thats what i have always heard too, i will give it another day or so before i get to concerned

That's what happened with Irene for Florida, definitely interesting; perhaps intense tracking times coming up.

[SeminoleWind]

Anyone think this will get renumbered by 5AM or even 8?

[Riptide]

Anyone think this will get renumbered by 5AM or even 8?

It has been a TD/TS for some time, guessing that NHC is waiting for more sustained convection and that's what we are now getting.

[tcast305]

Anyone think this will get renumbered by 5AM or even 8?

If it would it would be at 5am or 11am unless a special advisement.

[boca]

Anyone think this will get renumbered by 5AM or even 8?

If it would it would be at 5am or 11am unless a special advisement.

Its very hard to tell if it will be at 5am or 11am its so large and it has to consolidate which its trying to do but its hauling west so fast its taking its sweet time.

[SeminoleWind]

t has be a TD/TS for some time, guessing that NHC is waiting for more sustained convection and that's what we are now getting.

Cant argue with you there, it already looks like a decent T.D. i was thinking 5 am so they could get at least a visible look.But it seems to be holding convection nicely.
Man this could be a huge storm and i mean area not so much strength.

[tcast305]

Anyone think this will get renumbered by 5AM or even 8?

If it would it would be at 5am or 11am unless a special advisement.

Its very hard to tell if it will be at 5am or 11am its so large and it has to consolidate which its trying to do but its hauling west so fast its taking its sweet time.

Boca,

Not saying it would, just clarifying that it would be at standard times that NHC releases advisories, unless 94L warranted releasing a special advisory.

[boca]

It seems like with 50w is the magical longitude line in which systems start to gain convection I knew last night 94L would start to pop due to the warmer ocean temps.

[brunota2003]

http://www.ndbc.noaa.gov/station_page.php?station=41040

Buoy is a full 3 degrees west of roughly where the center is (if the ball of convection at 50W is the center)...already winds are starting to go up, only to 15.5 knots (1-minute sustained) so far though.

[Fego]

Would this be the beginning?



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[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.

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.

Technically speaking, a cap(ping layer) is an temperature inversion; precipitable water ("moisture") isn't part of the equation.

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.

It's not the latitude, but rather how warm the overall atmospheric column is (so it's thick at the equator because it's warm there).

....In any case the research points to hot towers providing a buffer to the dry air.

A hot tower (if I may define it as a "CB exhausting at 200mb") exists in the first place because the high altitude cap gave way; the entrainment of (some) dry air into the circulation will mostly just degrade accessory convection at the periphery. The problem (from an analysis/study standpoint) is that there isn't enough recognition of the critical role the 200mb cap plays, leading to IMO over-emphasis on lower atmospheric factors (shear, dry air, etc) of IMO lesser importance.

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.

Velocity in and of itself is not an inhibitor -- it's just that a system is likely to be moving fast due to some other atmospheric condition which is more often than not hostile to tropical formation (such as an easterly surge off the Sahara).

Speaking of Ernesto, I recall posting of an interesting phenomena which occurred while the storm was still a mess southwest of Jamaica in a fairly uniform environment, but doing nothing. Around 10am (not normally a "go" time in the tropics as the diurnal minima is approaching), convection sprouted all over the system -- north side, center, south side. The CBs all begin rising simultaneously. -- When you see something like that, it's a dead tip off that a non-surface phenomena is in play.

My best guess: a gravity wave or other sort of invisible undulation traversed the tropopause, and broke the cap stifling the system.

[pavelbure224]

I can see there is going to be a lot of sleepless nights

[Zanthe]

Anyone think this will get renumbered by 5AM or even 8?

*image removed*

It has been a TD/TS for some time, guessing that NHC is waiting for more sustained convection and that's what we are now getting.

No, it hasn't been a TD or TS yet. To say that is very disrespectful to the NHC. Heck, a few hours ago there were people suggesting that the probabilities for development should be lowered for a lack of convection. A TD or TS isn't a TD or TS until the NHC declares it one. Not only is it disrespectful, but it's irresponsible to undermine the authority of the NHC by saying it's been a TD or TS.

I think we'll have a TD sometime today, so long as the convection can hold on, which it looks like it'll be doing. Really wonder what the NHC is going to do for the intensity forecast. Interesting times ahead. And sleepless nights.

[CrazyC83]

Recon is still a go for this afternoon? That would be the tell-tale sign IMO.

[HurricaneMaster_PR]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT TUE AUG 21 2012

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A WELL-DEFINED LOW PRESSURE PRESSURE IS LOCATED ABOUT 725 MILES
EAST OF THE LESSER ANTILLES. THUNDERSTORM ACTIVITY HAS INCREASED
AND BECOME BETTER ORGANIZED NEAR THE CENTER DURING THE PAST SEVERAL
HOURS. IF THIS RECENT DEVELOPMENT TREND CONTINUES...THEN A TROPICAL
DEPRESSION COULD FORM LATER THIS MORNING. THIS SYSTEM HAS A HIGH
CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WESTWARD AT 20 TO 25 MPH. THIS LARGE
DISTURBANCE COULD REACH THE LESSER ANTILLES BY WEDNESDAY...AND
INTERESTS IN THAT AREA SHOULD CLOSELY MONITOR THE PROGRESS OF THIS
SYSTEM SINCE TROPICAL STORM WATCHES COULD SOON BE REQUIRED FOR
PORTIONS OF THOSE ISLANDS.

[SunnyThoughts]

Recon is still a go for this afternoon? That would be the tell-tale sign IMO.

I'm quite sure its still a go, considering how the system looks at this point, and the fact it is at 100% of forming from the NHC now. Gotta get those islands warned fairly soon, they will probably pull the trigger at 5am and not wait for Recon, but thats just my opinion. I suppose they could actually wait another few hours until recon gets there to name it, but I don't think they will wait that long considering its proximity to the islands and the rate of speed it's traveling.

[hurricanetrack]

There you go....and there it goes. Like magic, it hits 50W and up goes the convection. Welcome to lots of lost sleep everyone. Enjoy.

[Shuriken]

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

Why hello thar, you purdy -75C meatball! (still not nice n' round, but cold tops definitely there).

[Fego]

AL, 94, 2012082106, , BEST, 0, 152N, 503W, 30, 1007, LO, 34, NEQ, 0, 0, 0, 0, 1013, 250, 35, 0, 0, L, 0, , 0, 0, INVEST, M,

For what is worth, Best Track says 94L is down to 1007 mb