Active Period Miscalculation?

[Frank2]

Before I mention this (in case everyone tells me to look at today's satellite photo) - the tropics seem to be getting more active today, but, it's worth mentioning something that came to mind this morning:

Last year, NOAA mentioned that we are currently in an active 15-20 year period of hurricane formation, however, since this period began in 1995, some 11 years ago, it's also possible, given the five-year range (15-20 years), that, we have prematurely reached the end of the active period of hurricane formation.

Unfortunately, many in the public, the media included, seemed to misinterpret last years statement to mean that 2004 was the beginning of a 15-20 year active period of hurricane formation. It also seemed that NOAA and many OCM's (especially those for TWC, CNN, etc.) did not try to clear this up by explaining that, as of last year, we were already (using the 15-20 year range) up to 2/3 of the way through the active period.

Again, since this active period varies by as much as 5 years, it's very possible that it might have ended early, after 10 years of mostly busy hurricane seasons.

Just a thought...

Frank

[Stormavoider]

I don't think one half of one season can be can be used as any trending indication.

[gtalum]

Also, even during an active peirod there will be some slower seasons.

['CaneFreak]

Frank,

I agree that the media is probably a little misled in the numbers but Frank we have been in this active period since 1995 and this is the 11th year in the active period. Given that, the AMO cycle can last for UP TO 30 or 40 years....the AVERAGE AMO cycle is 10 to 20 years....that means it could be longer or it could be shorter...not trying to misinterpret what you said...just making sure that we're not confusing ourselves in the process...but I DO agree with your statement...but with all due respect we could be in this cycle for MANY more years to come....

'CaneFreak

[Frank2]

No, but, as mentioned, it's just a thought...

Previous active and quiet periods average about 15 years each, so, it's very possible that at 11 years, the cycle has changed on the low end of the average...

Frank

[Frank2]

Since last season, I've heard more than one official or advertisement incorrectly state that we were at the beginning of a 20 year cycle of increased hurricane activity - again, since the cycle began in 1995, that's a very outdated statement (though "good" for business, I'm sure).

Frank

[Frank2]

True about the AMO, but, some (including Dr. Gray) have noted a 1-degree cooling of the Atlantic this year...

Frank

[KWT]

As always with these things Frank one season means very little on its own and as much as the 2005 season was not a sign of things to come, the 2006 is probably just one of those less manic years that have to occur once in a while, esp when the SOI is as negative as it is and you've got strong sub-surface warming which is akin to El nino.

This is going to be a bust I rekcon for Dr,Gray and NOAA, the Atlantic is not as active as was expected and the EPAC is going to be certainly on the upper end of what was expected at least.

[Frank2]

True enough - we'll see...

[Extremeweatherguy]

I would not label 2006 as below normal or an odd season just yet. We could very well still end up above average. If Dr. Gray's prediction of 15 storms is correct, then this year will be anything but quiet.

[KWT]

Indeed if we do get those sorts of numbers then fair play Extremeweatherguy but I think we are going to be very much on the lower end of what was expected. I noted that one of the main reasons why they went for 17 storms in the first place is the AMO is in its favorable mode for the Atlantic and that it was one of the 3 main features of note. I actually think they've put too much faith into this and not actually looked at the sub-surface warming that rapidly took place and the very negative SOI that was already starting to occur by the time that 17 NS forecast came out, and while we may still have offical Neutral condtions, the Pacific is closer to El nino then Neutral I reckon and that trned was already present by that forecast...

[hurricanetrack]

No, but, as mentioned, it's just a thought...

Previous active and quiet periods average about 15 years each, so, it's very possible that at 11 years, the cycle has changed on the low end of the average...

Frank

I just think that by saying "it's very possible" that you would need some kind of evidence to back it up. Of course, we could point to no hurricanes by August 20, 2006 as evidence that all of a sudden the active period has come to an end and now we will go back to having 10 named storms per season overall.

I would imagine that this would make for a great story for CNN and National Geographic. We were told that we could possibly see 20 years+ of increased Atlantic hurricane activity, but then, all of a sudden, the very year after our biggest season on record, everything went back to normal. Sea surface temps cooled to normal, the salinity values went back to normal, the thermohaline circulation is now back on track, as it was pre-1995 and Africa is back in a drought- although the rainfall in the Sahel was not as big a deal as Gray, et al originally thought. With this dramatic change in the tropics that was unforeseen by the world's greatest scientists in that field, I think it would make for a great documentary. Perhaps even some questions would need to be raised about how such large scale indicators could even be missed. Afterall, we were looking at a 17 named storm season just three months ago- and since then, it is "very possible" that the current active period of increased Atlantic hurricane activity either decreased or ended completely. I am looking forward to reading the September update from Gray and Klotzbach as there should be something mentioned in there about the possibility of a premature end to the current active cycle. I would think that Frank is not the only person in the world to have stumbled on to this as a possible explanation as to why we have had zero hurricanes in the Atlantic this season.

[wxman57]

FYI -- I've done considerable research on hurricane activity from 1851-present. During the last "active cycle" (warm Atlantic phase), there were no more named storms than during the cold phase. In face, I got an average of about 0.1 less named storms per season when the Atlantic heated up in the 1930s-1960s.

However, there were about twice as many major hurricanes when the Atlantic heated up and many more landfalling major hurricanes. So "active cycle" does not necessarily mean more named storms.

[Jim Hughes]

FYI -- I've done considerable research on hurricane activity from 1851-present. During the last "active cycle" (warm Atlantic phase), there were no more named storms than during the cold phase. In face, I got an average of about 0.1 less named storms per season when the Atlantic heated up in the 1930s-1960s.

However, there were about twice as many major hurricanes when the Atlantic heated up and many more landfalling major hurricanes. So "active cycle" does not necessarily mean more named storms.

I'd love to see the hard numbers on this. 1900- 1930 was less active than 1930-60. So I am trying to figure out where you are getting these higher Cold averages from. 1851- 1900?

This would be an unreliable data base to rely on especially when trying to figure out the AMO phase. The latter seems to be related to temperatures in the stratosphere and this seems to be related to space weather changes. So I am very sorry but I am skeptical about all of this.

[wxman57]

FYI -- I've done considerable research on hurricane activity from 1851-present. During the last "active cycle" (warm Atlantic phase), there were no more named storms than during the cold phase. In face, I got an average of about 0.1 less named storms per season when the Atlantic heated up in the 1930s-1960s.

However, there were about twice as many major hurricanes when the Atlantic heated up and many more landfalling major hurricanes. So "active cycle" does not necessarily mean more named storms.

I'd love to see the hard numbers on this. 1900- 1930 was less active than 1930-60. So I am trying to figure out where you are getting these higher Cold averages from. 1851- 1900?

This would be an unreliable data base to rely on especially when trying to figure out the AMO phase. The latter seems to be related to temperatures in the stratosphere and this seems to be related to space weather changes. So I am very sorry but I am skeptical about all of this.

You can easily go to the Unisys web site, click each year, and average the number of NS/H/IH for any period:

http://weather.unisys.com/hurricane/atlantic/index.html

Cold cycles: 1900-1925 and 1970-1994

Warm cycles: 1926-1969 and 1995-2005

[MWatkins]

This discussion seems familiar...like it happened almost exactly this time last season.

Oh wait...it did...almost to the day.

http://www.storm2k.org/phpbb2/viewtopic ... highlight=

And look where we ended up.

MW

[Brent]

This discussion seems familiar...like it happened almost exactly this time last season.

Oh wait...it did...almost to the day.

http://www.storm2k.org/phpbb2/viewtopic ... highlight=

And look where we ended up.

MW

Ouch.

[hawkeh]

^^^^

Yep definately season cancelled

<Im being sarcastic>

[Weatherfreak14]

This discussion seems familiar...like it happened almost exactly this time last season.

Oh wait...it did...almost to the day.

http://www.storm2k.org/phpbb2/viewtopic ... highlight=

And look where we ended up.

MW

Ouch.

Yeah, ouch, but for some reason last year, I cant remember this much shear but i guess at my young age I have bad memory.

[Extremeweatherguy]

This discussion seems familiar...like it happened almost exactly this time last season.

Oh wait...it did...almost to the day.

http://www.storm2k.org/phpbb2/viewtopic ... highlight=

And look where we ended up.

MW

wow. It is amazing how similar the discussions were this time last year!



BTW: Here are a few different (and interesting) comments I pulled off that thread:

Aug. 14th, 2005:

A mere six weeks or less from now, the current (and annually occurring ) concern regarding "hostile conditions" and talk of "what's stopping development?" will seem laughable in retrospect.

This was a great comment, and ended up being 100% correct.

Aug. 14th, 2005:

It's true that last year many of us (including myself) were commenting in July on just how quiet everything was - until August came, however, this year shows the hallmark of other seasons that were very active in their early stage, but suddenly turned quiet - and remained that way.

One meteorological reason for this to happen is perhaps because the environment has changed during the season, which can turn an active season into a quiet one - or just the opposite, as was the case last year.

It's very possible, in reference to the initial comment here, that the season will remain unfavorable for the development of "healthy" tropical cyclones through the remainder of the season. Considering that Franklin, Harvey and Irene were all "unhealthy" (or weak) tropical storms, this seems to possibly be the case.

Some here and elsewhere on the board have mentioned the ridge to build in again in the weeks ahead, but, this is not the case, since, it's known to forecasters that the subtropical ridge actually begins to break down and move eastward beginning in late August, and, while there may be a temporary rebuilding of the ridge in September, increasing weateriles and southward moving cold fronts usually make any rebuilding short-lived.

I know some here want to hear otherwise, but, after spending approximately 12,000 hours at the NHC, you get to observe various weather patterns from one season to the next, and in your heart you get to recognize them for what the are, and, while that's not to say that we will not see anything else this season, the pattern seems to now be there for a less active season than was originally predicted.
Sincerely,

Frank

I am seeing these same type of comments this year, and it goes to show that they are not always correct.


Aug. 14th, 2005:

Frank-

I'm getting the feeling that the 2005 season is winding down. If you simply graph the distribution of the storms:

A B C D E F G H I X
TS TS TS C4 C4 TS TS TS TS TD

We went from tropical storms, to two major hurricanes, back to tropical
storms, and a pathetic depression.

We may see 3-4 more storms this year, but the conditions are not as
favorable as they were early in the season. I suspect Dr. Gray will
lower his numbers slightly, come September 1.

This once again goes to show that you should never give up too soon on the tropics. That 3-4 more storms turned into 15+...the same type of thing could indeed occur this season too.

Aug. 14th, 2005:

Andrew92,

I must agree with you, I think that because we had such an early start to the season that people tend to forget that the peak is still a month away. Everyone needs to be patient there is more to come.

Ken

This comment was as good then as it is now and is still very true. the peak is not even here yet, and we all need to remember that!

Aug. 15th, 2005:

I think in a couple of weeks we will be drinking tons of coffee and praying a lot.

How right you were..