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Atlantic Tropical Action 2012 - Part II


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If the Euro is correct with the weakening of the El Nino pattern in October, we could still

see a few more Atlantic named systems later in the season. This was a change for the

Euro from it's forecast last month.

Be careful when assessing the state of ENSO using SST data and then trying to make a prediction of Atantic tropical cyclones. The determining factor whether the Atlantic shuts down or not is if the atmosphere is responding to the SSTs in the Pacific. We have yet to seen any atmospheric response to ENSO this summer. The atmosphere still thinks we are in a La Nina! So I wouldn't hold any confidence in the Atlantic having a basic EL-Nino type of season, since we are still experiencing low-values of globally averaged Angular Momentum (which can be interpreted as a La Nina base state).

gwo_fnl.gif

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If the Euro is correct with the weakening of the El Nino pattern in October, we could still

see a few more Atlantic named systems later in the season. This was a change for the

Euro from it's forecast last month.

Most of the weakening is in September, which has verified quite well...we are probably more in a La Niña like pattern than a Niño. We probably peaked at +0.9 in the weeklies a few weeks ago. Most probably, the next weekly update will be back in the warm neutral range. I still expect late season TCs in Oct and Nov.

Dramatic how things changed in the last couple of weeks.

post-29-0-62384400-1348233285_thumb.gif

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Alternatively, one might argue that the month long slope of AAM has been upward and this is typically the time of the season in which the effects of a developing El Nino start asserting themselves.

Could be...the next MJO wave in mid-late october will show what this warm ENSO is really made of, probably.

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Alternatively, one might argue that the month long slope of AAM has been upward and this is typically the time of the season in which the effects of a developing El Nino start asserting themselves.

You're right- it is trending upward. Just making an illustration to fair warning when trying to use an ENSO-derived index of SSTs and Atlantic TCs :)

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For those who are interested, I have created a Kelvin-wave phase-space diagram to track strong Kelvin waves. I use a simliar methodology to WH04 but with Kelvin filtered VP200. The EOFs show a wavenumber 2 patter, so you'll get two ridges/troughs. Anyway, I'm not too sure how it will pan out but it might be a useful tool to track KWs with strong upper-level circulations. Climatologically, genesis is most favorable between Phases 2-4, and less favorable between phases 7-1. A July-September composite of unfiltered VP200 anomalies and 200 hPa wind anoamlies when amplitudes are greater than 1 sigma can be found here.

filterKELVIN_vp_Phase.png

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Thinking back to previous page, possibly 5 non-tropical genesis events, that just feels warm ENSO, even if certain atmospheric indices haven't responded correctly.

The early season developments killed me in the tropics contest, because I just had such 1997 flashbacks (the warm AMO had already begun, a developing Nino, 4 non-tropical developments culminating in Danny) and I remembered 2009.

Anyhow, a mid-late October MJO wave, I try to stay glass half full optimistic, but that is past Opal range and into the rarefied air of a Wilma. That was an unusual year, however, that spoiled people on forums for years after.

Using GEFS spaghetti, which worked pretty well as an amateur's quick-look for me in July and August as an indicator of when the uptick would begin, even the EPac is pretty slow except for the cherry until almost the end and there is no suggestion of Atlantic activity really through 2 weeks.

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Thinking back to previous page, possibly 5 non-tropical genesis events, that just feels warm ENSO, even if certain atmospheric indices haven't responded correctly.

The early season developments killed me in the tropics contest, because I just had such 1997 flashbacks (the warm AMO had already begun, a developing Nino, 4 non-tropical developments culminating in Danny) and I remembered 2009.

Anyhow, a mid-late October MJO wave, I try to stay glass half full optimistic, but that is past Opal range and into the rarefied air of a Wilma. That was an unusual year, however, that spoiled people on forums for years after.

Using GEFS spaghetti, which worked pretty well as an amateur's quick-look for me in July and August as an indicator of when the uptick would begin, even the EPac is pretty slow except for the cherry until almost the end and there is no suggestion of Atlantic activity really through 2 weeks.

Might it be that the atmosphere just isn't responding to ENSO as much as what was originally predicted, instead of most atmosheric indices not correctly responding?

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Most of the weakening is in September, which has verified quite well...we are probably more in a La Niña like pattern than a Niño. We probably peaked at +0.9 in the weeklies a few weeks ago. Most probably, the next weekly update will be back in the warm neutral range. I still expect late season TCs in Oct and Nov.

Dramatic how things changed in the last couple of weeks.

post-29-0-62384400-1348233285_thumb.gif

I think that really negative PDO for August was a hint at where we are now. It looks like we have to go all

the way back to 1955 to find a lower value.

http://jisao.washing.../pdo/PDO.latest

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This has been a complete garbage season. You're the weenie for being a name queen.

The average Atlantic season is 11/6/2 (tropical storms/hurricanes/major hurricanes), this year we have 14/8/1 if we have nothing more from here on out, and if other storms don't get added/upgraded post season. So no, you're the weenie.

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The average Atlantic season is 11/6/2 (tropical storms/hurricanes/major hurricanes), this year we have 14/8/1 if we have nothing more from here on out, and if other storms don't get added/upgraded post season. So no, you're the weenie.

Sophisticated people can use more than simple counts to make arguments. I expect more from a teen weather genius.

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Even in the unlikely event that a new TC forms, the increasing AAM and shifting convective phase globally should shift the MJO sufficiently so that the persistent long-wave trough over the Eastern CONUS should weaken during the first half of October--thereby shutting down the chances of a U.S., meaning FL-based, threat from the Caribbean due to a building W Atlantic ridge. The 12Z ECMWF and its ensembles show this likelihood beginning in about a week. Anything that would attempt to develop in this pattern would quickly move into Mexico before developing. Basically, we are seeing a crappy August-like pattern in the wavelengths that should have been in place during prime Cape-Verde time over the last few years (2010-2012) but was not. (And anyway, the strong, subtropical, southern jet that is typical of developing Niño events should finally start to kick in as the AAM shift should mean the Niña-like atmosphere will finally respond by mid-October.)

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Not only Nadine is still alive and kicking @ day 10 in the 12z Euro, but the whole pattern is August like with a heat ridge in TX and a strong Bermuda ridge ...

post-29-0-34504800-1348434128_thumb.gif

If that pattern had been around in August or September, Ernesto would have been an Okeechobee 1928 redux. :axe:

Typical pattern over the last three seasons--nothing seems to align perfectly, even seasonally, for a major U.S. landfall, whether it is the AAM, the MJO cycle, the strength of the Hadley cells, the vorticity stretching in the N Hemisphere (which has favored numerous upper-level lows over the tropics), the Plains ridge (which has basically turned every Cape-Verde TC into an instant fish), etc....

Even though it is improbable, I am just bracing myself for more of this crap next year. (Maybe I am only half-joking. :flood: )

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if you're measuring total energy dissipation, ACE is the only relevant number. If you're talking about the coolness of a season, there can be overriding metrics. I'm done arguing with you because you're obviously infatuated with garbage 55 kt TSs. Your definition doesn't match the rest of the boards but whatever. I'm sure you'll continue being a stubborn meat head about it.

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Since I'm all about coolness over numbers, I've never given a half crap about ACE.

My early season fantasy football like scoring I think will do okay. Computing it for past years may prove difficult. Somone said why don't you just use ACE, I think I replied because of the 2011 season.

About the lack of major landfalls, there has been a lack of activity in the Gulf and Caribbean since 2008. Keith and ALex were the only notable storms in the region, everything else has been a slopgyre. The gulf especially is key for major US landfalls even if majors don't form there they usually pass through it, and everything in that area has looked like **** since 2008.

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