Atlantic hurricane season halfway point

Tropical Storm Hermine rapidly developed and has moved into South Texas soaking rather moist ground from previous Hurricane Alex and TD2.  Scattered areas of interest in the Atlantic include the remnants of Gaston and a couple African Easterly Waves about 3,000 miles from the United States mainland.  Each has a low chance of tropical cyclone development in the next 48-hours according to the NHC.  Long-range forecast models are bullish on wave number 3 eventually developing as it moves westward.

Accumulated Cyclone Energy to date (thru September 8) in the North Atlantic is 63.  In a previous post (Earl Sputters…), the climatological trace of ACE showed the Atlantic being about 8-10 days ahead of normal (1950-2009 historical records).   Many other images also float around the internet and show that the half-way point of the Atlantic season is roughly September 11.

From 1950-2009, there are many seasons in which Atlantic hurricane activity is very weak, with only a few storms of marginal strength which produce low amounts of ACE.  Out of the last 60 seasons, there are 17 that have an ACE of less than 63 (including last year’s 53), which is coincidentally the tally through September 8, 2010.  Thus, 2010 is number 18 from the bottom in terms of ACE so far, with still half the season to go.  As each storm develops, more ACE will move 2010 up the rankings, but how far?

Figure: the percentage of the total season’s ACE left in the second half of the season (y-axis) as defined as September 11, with the bubbles size scaled by the overall season’s ACE.  The mean is 48% but the standard deviation is 20% indicating a huge spread.   Data source.

This figure exemplifies part of the reason why seasonal forecasting is so difficult for ACE in April or even in August.  Tropical storms and hurricane activity in the North Atlantic varies intraseasonally as well as interseasonally in terms of genesis locations and track configurations, which are the critical components of the ACE metric (frequency x duration x intensity).  The North Atlantic is sometimes called the “marginal basin”.  The trick is to somehow gain a level of confidence in your forecast either through persistence or knowledge of the prevailing large-scale climate (i.e. ENSO, AMM, NAO, etc.) as NOAA, Gray and Klotzbach, and other long-range climate forecasting outfits.

Interestingly, the past 3-years have seen less than a quarter of their yearly output past September 11, the climatological peak of the season according to the past 60-years of data.  Keep track of global tropical cyclone ACE at Ryan Maue’s FSU page.

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19 thoughts on “Atlantic hurricane season halfway point

  1. I don’t really disagree with the data shown, but each hurricane season is as different as a child in the same family without birth control.
    What the heck are you talking about?
    If we go back into a farmer’s history, a family didn’t have birth control a hundred years ago. A woman beget until she couldn’t anymore or died in child birth.
    Along the way, their we’re miscarriages, still born, etc. Ending up with roughly 12 children. The oldest might be 20 years older than the youngest.
    So, how does that compare to hurricane seasons?
    Having looked the historical numbers over, the season can be over or it might float right up to Christmas day. Each season is different.
    What is in its favor this year?
    What is left over from the hottest decade on record, 1998 to 2007. The Earth is cooling from the lack of sunspots.
    The next two cycles will be cool per Joseph D’Aleo.
    This farmer’s wife (the last 100 years), so to speak, is at the end of her life time cycle of birth. This season may be over now or in the next 6 weeks.
    We should record carefully what we are seeing so as to fully understand the affects of the lack of sunspot activity has on building a hurricane season.
    As noted in the Jan. 1878 Edition of Popular Science magazine which can be found on line, fewer sunspots mean fewer hurricanes.
    We need to understand the overall life cycle of a century.
    We need to understand that hurricanes, tropical storms and depressions are vital to our weather, water tables and ecology. I can’t help it if people park their lives on a beach or behind a levy and wonder why “God destroyed their way of life.?”
    I cannot understand why our government is trying to rebuild New Orleans between levies and a lake dam when it forces towns along the US rivers to find higher ground after the 2d or 3rd flood.
    It has to be politics and votes.
    I shall step off my soap box at this time.
    Paul

  2. Jim Arndt says:
    September 7, 2010 at 1:47 pm
    …and if in the next SH summertine la Niña can’t get any warmer then don’t buy popcorn but marshmallows 🙂

  3. Paul Pierett said:
    “As noted in the Jan. 1878 Edition of Popular Science magazine which can be found on line, fewer sunspots mean fewer hurricanes.”
    More anecdotal evidence in support of a solar effect on the air circulation systems.
    It appears that a quiet sun somehow causes a more negative polar oscillation which shifts all the air circulation sytems equatorward thereby reducing the distance available for tropical depressions to wind themselves up into hurricanes.
    Several have already mentioned the dryer air up aloft which is nearer the equator than previously and apparently limiting hurricane development.
    The evidence just keeps accumulating.

  4. At the time of this writing, causes for (and predictability limits of) the PDO are not known. What is known is that the nature of the mechanisms giving rise to the PDO will determine whether or not it is possible to make decade-long PDO climate predictions.
    The above was written by: By Nathan Mantua, Ph. D.
    Joint Institute for the Study of the Atmosphere and Oceans
    University of Washington, Seattle, Washington, USA.
    http://www.atmos.washington.edu/~mantua/REPORTS/PDO/PDO_cs.htm
    I have no idea what the climatology experts do, but I do know that there is natural process, not caused or affected by any of the Earth’s climate parameters, which is highly correlated to PDO with a realistic physical mechanism to generate it.
    http://www.vukcevic.talktalk.net/PDOa.htm
    Well, I suggest to professor Dr. Mantua (in case he is a visitor to these pages) to get in touch, we could have an interesting exchange of views.

  5. We were treated to scare stories on TV here in the UK when Earl was heading for The North American East Coast. Yet it looked, to me, even early on as if Earl was following quite closely the track Bill had taken only one season earlier. (Bill stayed at sea and nearly reached Iceland before he fizzled out.)
    The scare story I remember best was done by somebody who was labelled as a “Hurricane Specialist” He never once during his presentation mentioned fossil fuels or AGW with a single word, yet at the end of it all I had no doubt that any ensuing devastation could be laid fairly and squarely at the feet of mankind in general and me and other viewers in particular.
    I still wish I had recorded the program but alas I did not. All I can say therefore is: It was very cleverly done and maybe such are things to come; ‘No need to mention AGW any more because the seed of guilt has already been planted in most people’s minds and they themselves will make up the necessary link.

  6. O H Dahlsveen says:
    September 7, 2010 at 3:31 pm
    “We were treated to scare stories on TV here in the UK when Earl was heading for The North American East Coast. Yet it looked, to me, even early on as if Earl was following quite closely the track Bill had taken only one season earlier. (Bill stayed at sea and nearly reached Iceland before he fizzled out.)
    The scare story I remember best was done by somebody who was labelled as a “Hurricane Specialist” He never once during his presentation mentioned fossil fuels or AGW with a single word, yet at the end of it all I had no doubt that any ensuing devastation could be laid fairly and squarely at the feet of mankind in general and me and other viewers in particular.
    I still wish I had recorded the program but alas I did not. All I can say therefore is: It was very cleverly done and maybe such are things to come; ‘No need to mention AGW any more because the seed of guilt has already been planted in most people’s minds and they themselves will make up the necessary link.”

    I’ve noticed the BBC are no longer screaming ‘CAGW’ at the end of any extreme weather event. I don’t think it’s because they think it unnecessary, rather they are hedging their bets following the Climategate and IPCC fiasco’s. Climate science has been badly damaged and, as seems likely, a long period of cooling occurs then they don’t want to be seen as part of the scam.
    The MSM is too important an asset for those in power and they don’t want it to be damaged and rendered useless for the future.

  7. “The MSM is too important an asset for those in power and they don’t want it to be damaged and rendered useless for the future.”
    Too late.

  8. Joe Bastardi told us a few weeks ago that La Nina years tend to be less active than normal early in the year but more active than normal later in the year.
    When you think about it, it does make sense. La Nina has a nasty habit of making the southeast US hot and dry, this year being no exception because this is one of the hottest years ever in the southeast US. Tropical cyclones have a warm core formed initially by thunderstorm activity. Thunderstorms are more likely when cold and hot air mix. The worst storms occur in the spring and autumn. This effect is readily noticed in “tornado alley”, the central US where cold air can more readily come down and mix with warm air. This is also the reason why a warmer earth means less hurricanes, not more.

  9. We Floridians have learned (especially after 2005) to watch every storm and judge it on it’s own. I lay in a decent amount of hurricane supplies every year and don’t relax until Thanksgiving.
    ….had to laugh last year when they railed that global warming was going to bring endless streams of ’em and nothing happened to us, tho….

  10. Enneagram says:
    September 7, 2010 at 1:58 pm
    …and if in the next SH summertine la Niña can’t get any warmer then don’t buy popcorn but marshmallows
    ___________________________________________
    ROTFLMAO, I always enjoy your comments but that one has to be one of the best. Pithy and to the point.

  11. Gerry,
    Its been a while since we have had a good hurricane party in Central Florida.
    I had to drive through a major hurricane after Charlie to get back to Georgia for work the next day.
    I left in the middle of the eye and drove against east to west bans for three hours. Sand drifts covered the road on Rt 27 south of Florida Turnpike.
    It was a white knuckle trip
    I hadn’t been in a storm like that since a winter blizzard hit Indiana in 1984.
    I didn’t do much this year to lay up supplies but for a week. I still have stuff left over from last year and the years before. I don’t expect much this year.
    Paul

  12. Wade @ 4:50 pm
    I just finished a half-bottle of Chardonnay and maybe that’s why I didn’t keep up with you. I started out reading about the Atlantic Hurricane season and then I was reading about “tornado alley” and warm and cold air mixing (like a dance maybe?). Then back to “a warmer earth means less hurricanes, . . .”
    I’m so confused, I think I need the other half of that Chardonnay.

  13. Dr Maue
    Have you (or others) noted any connection between your hurricane frequency/strength data and the Global Ocean Conveyor slowdowns and spurts, say on a seasonal or annual basis? I understand this thing is noted for longterm weather effects, but it sure seem like it would also have short term impact on the frequency/strength of major storms.

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