SST Anomalies In The Hurricane Nursery

File:Cape Verde hurricane track.jpg

By Steve Goddard

Thanks to Dr Klotzbach for his excellent post describing his thinking behind the CSU hurricane forecast.

A number of readers asked about SSTs in the hurricane nursery. So I took the most recent Unisys SST anomaly map, removed all colors between -0.5°C and +0.5°C, and overlaid the most recent tropical storm map on it.

Note that the only region (1) with any chance of turning into a hurricane is located in water that is essentially normal (+/- 0.5°C) temperature.

NOAA describes it as follows :

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LOW PRESSURE SYSTEM LOCATED ABOUT 750 MILES NORTHEAST OF THE NORTHERN LEEWARD ISLANDS HAVE CHANGED LITTLE IN ORGANIZATION DURING THE LAST SEVERAL HOURS. UPPER-LEVEL WINDS ARE MARGINALLY CONDUCIVE FOR DEVELOPMENT…AND ANY INCREASE IN THUNDERSTORM ORGANIZATION COULD RESULT IN THE FORMATION OF A TROPICAL DEPRESSION AT ANY TIME. THERE IS A HIGH CHANCE…70 PERCENT…OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES TOWARD THE NORTH AND NORTH-NORTHEAST OVER THE ATLANTIC.

2010 hurricanes are right at the 1944-2005 average of one for the date. There have been years (like 1969) which started slow but took off in mid-August. We will know soon if 2010 will turn into of those years.

http://www.weatherstreet.com/hurricane/2010/Hurricane-Atlantic-2010.htm

Afternoon update:  region 1 has been downgraded.

A LOW PRESSURE SYSTEM LOCATED ABOUT 700 MILES NORTHEAST OF THE

NORTHERN LEEWARD ISLANDS HAS BECOME LESS ORGANIZED THIS

AFTERNOON…AND DEVELOPMENT APPEARS A LITTLE LESS LIKELY DUE TO

STRONG UPPER-LEVEL WINDS. THERE IS A MEDIUM CHANCE…50

PERCENT…OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT

48 HOURS AS IT MOVES TOWARD THE NORTH AND NORTH-NORTHEAST OVER

THE ATLANTIC.

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49 thoughts on “SST Anomalies In The Hurricane Nursery

  1. The atmospheric conditions and SST are primed for some strong activity in the Atlantic. There is no denying this. The rest of the world is another story altogether.

  2. Calling individual storms is a mugs game.
    It appears that we have conditions which, all things being equal, could create significant hurricane action.
    So the interesting question is whether or not the conditions which the science says will create those storms actually do. If they do, then for this season “the science is settled”.
    But what if they don’t?

  3. What’s up with that nice, neat circular swirl at the mouth of the Mississippi, this morning? It doesn’t exactly look like a “dissipated low” to me.
    http://radar.weather.gov/ridge/radar.php?product=N0V&rid=MOB&loop=yes
    Meanwhile we are bone dry in Southern New Hampshire. Every cotton pickin’ thunderstorm has missed us all summer, and the heavy rains out in Iowa seems to wring all the moisture from eastern-moving systems. We sure could use a “dissipated tropical low” in these parts. I’ve never seen my farm pond so low.

  4. I hear Greenpeace are releasing many thousands of butterflies off Cape Verde islands in the hope that at least one pair of tiny wings will do the trick………….

  5. Sometimes all it takes is for a butterfly to open it’s wings…..
    [Isaac’s storm reference – Galveston Hurricane, Sept. 8, 1900]

  6. Lulo says:
    August 12, 2010 at 12:07 am
    The atmospheric conditions and SST are primed for some strong activity in the Atlantic. There is no denying this. The rest of the world is another story altogether.
    I wouldn’t hold the atmospheric conditions and the SST’s as the most important factors , any more than I hold the SSN# as the overarching factor. When the canes are taken shape, you watch the tracks and prepare to get out of the way.
    When the spots get really weak or disappear, you prepare for the consequences that the literature speaks of.

  7. John A says:
    August 12, 2010 at 1:47 am
    Randomness/Chaos exists only in the mind of the beholder.

  8. stevengoddard says:
    August 12, 2010 at 4:51 am
    “2010 is now lower SSTs than the very slow hurricane year of 2006 – which was also forecast as a big season by all the experts.”
    Here’s another “blast from the past” link:

    2006 hurricane forecast: 8-10 storms
    U.S. Government experts say 4-6 could be major
    updated 5/22/2006 8:50:26 PM ET
    MIAMI — The 2006 Atlantic hurricane season will be very active with up to 10 hurricanes, although not as busy as record-breaking 2005, when Hurricane Katrina and several other monster storms slammed into the United States, the U.S. government’s top climate agency said on Monday.

    Also…

    U.S. hurricane experts say the sharp rise in storm activity is related to a natural shift in climatic conditions and sea surface temperatures in the Atlantic that is expected to last from 15 to 40 years.

    So what really happened?

    2006 hurricane season bows out quietly
    November 30, 2006
    Defying predictions, the 2006 Atlantic hurricane season ended with a whimper rather than a bang on Thursday, without a single hurricane hitting U.S. shores.
    Only three tropical storms made landfall, a welcome relief from the previous two years, when nearly a dozen hurricanes battered the country.
    The sense of quiet was relative. Although 2006 might have seemed tame compared with the devastation of 2004 and 2005, the season’s totals — nine named storms, five hurricanes, two of them major — were actually right at the historical average for the past 150 years, according to data from the National Hurricane Center.

  9. Lulo says:
    August 12, 2010 at 12:07 am
    The atmospheric conditions and SST are primed for some strong activity in the Atlantic. There is no denying this.
    Well…gee, I don’t know about that. Most every system so far has been torn apart or choaked by shear &/or dry air. If those issues do not change (less shear, deeper moisture) , it does not matter what initial systems/disturbances there are – the will not survive to be anything. It’s almost like the El Nino effects of last year are hanging on into the Atlantic basin. As with everything, time will tell.
    Jeff

  10. Earlier in the season I think the cool pool that attracted people’s attention was further north than the MDR. Keep in mind there’s more to hurricane formation than SSTs, though the MDR is very important in major Cape Verde hurricanes.
    I like Bob’s graph, but note that 2005 and 2006 weren’t all that far apart. I’ve mentioned that I like the Klotzbach/Gray post-mortems, for 2006, they summarize in http://hurricane.atmos.colostate.edu/Forecasts/2006/nov2006/nov2006.pdf :

    [Cover page] The 2006 Atlantic basin hurricane season had activity at slightly less than average (1950-2000) levels. This activity was much less than predicted in our seasonal forecasts.

    [Abstract] Our 2006 seasonal hurricane forecast was not successful. We anticipated a well above-average season, and the season had activity at slightly below-average levels. We did catch this downward trend beginning with our early August update We attribute a large portion of this forecast over-prediction to a late-developing El Niño and increased mid-level dryness in the tropical Atlantic.
    Our August-only forecast was a bust. Our September-only forecast was quite successful, especially when evaluated against the Net Tropical Cyclone (NTC) activity metric. The October-only forecast also successfully called for activity at well below-average levels, and no tropical cyclone activity occurred after October 2.

    So, that was the year that El Ninño shut things down mid-season.
    A hurricane forecaster who calls one of their forecasts a bust – one of the reasons I like them so much.
    Note the reference to “slightly below normal” – that covers the whole record, it was quite below the “normal” of the high THC periods, and the post El Niño months were probably below the long term average. I wouldn’t call 2006 a “very slow hurricane year.”
    El Niño is one of various things that can squash a season’s activity. I’ve mentioned Saharan dust before. One thing I want to look into is the Madden-Julian (sp?) Oscillation, that has a period of a month or so and has a big impact on storm formation, though it generally evens out over the season.

  11. Perhaps we are seeing a change in ocean and atmospheric behavior toward behavior that has not been seen for more than a century. All the clever little statistical tools like ‘Nino 3.4’ and such metrics were useful during the early part of the relatively predictable satellite era but the chaotic climate system is perhaps ponderously moving out of that eddy into a different state. All the clever statistical pattern matching may suddenly cease to work. This could explain the failure of the UK Met Office to get things right over the last few years.

  12. It is very nice to read all the stories , but really nobody is addressing the constantly lowering SST – anomalies in the birth region of the mid-atlantic tropical depressions , where most likely a lower than normal temperature will start to appear in the coming months when the present development from the last winter is going to be continued …. So what are the chances , an intensive hurricane season when the food for these hurricanes is disappearing ?

  13. Looks like we are in a down-trending NAO, with the start of southward displacement of the polar vortex (about 45 days early, seasonally, hence the flooding rain in Iowa). East coast trophiness is coming and opening up the gate for landfalls. If the subtropical jet would die down, something should pop and cause some aggravation, maybe as far north as Long Island.

  14. I know nothing about hurricanes. However, I am surprised that if conditions are right for a very active season, as Dr. Klotzbach suggested, then why do not storms such as Colin, turn into hurricanes? We have just seen a flurry of areas of disorganized showers not turning into named storms. I just find it difficult to understand why, if conditions are ripe for hurricane formation, hurricanes are not forming from disorganized systems which HAVE formed.

  15. The primary purpose of the annual hurricane hysteria is to sell TV advertising. I would have thought that most folks had figured that out by now.

  16. Hurricane Main Development Region (MDR) wrt Greening of Sahel
    I seem to recall that tropical cyclone initiation is associated with summertime dust transport from Africa over the North Atlantic in the hurricane Main Development Region (MDR). The MDR is ‘an area in the tropical North Atlantic where a majority of major hurricanes form, defined as 10-20°N, 20-70°W’.
    Thinking about that region reminded me of the Greening of Sahel article, which indicated the sub-Sahara region was both ‘greener’ and expanding north toward Sahara desert areas.
    Using the islands at Cape Verde (16 °N) as reference, it looks to me like the Sahel to Sahara greening (12 to 16 °N) is somewhat in line with the MDR (10-20°N) area.
    Speculation – Might a continued greening in Sahel affect the summertime dust transport? Or possibly affect the moisture content, frequency or intensity of the ‘waves’ from Africa out over the MDR? And what, if any, affect might that have on tropical cyclone initiation events? Do earlier Sahel droughts correspond with patterns in tropical cyclone activity?
    I have not found articles that consider changes in Sahel + MDR + dust, but these links speak to the individual topics.
    Greening of the Sahel
    http://www.eoearth.org/article/Greening_of_the_Sahel
    New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks
    http://www.agu.org/journals/ABS/2006/2006GL026408.shtml
    Klotzbach and Gray
    FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND LANDFALL STRIKE PROBABILITY FOR 2010
    http://typhoon.atmos.colostate.edu/forecasts/

  17. Jim Cripwell says: {August 12, 2010 at 7:43 am}
    “I know nothing about hurricanes. However, I am surprised that if conditions are right for a very active season, as Dr. Klotzbach suggested, then why do not storms such as Colin, turn into hurricanes?”
    SSTs are not the only condition that has to be right for tropical lows to turn into more intense storms and hurricanes. Upper level wind sheer is a huge factor, surrounding dry or moist air entering the circulation is another. And of course any disturbance that crosses land will experience disruption in the circulation. All this and perhaps Richard Holle’s explanation, which we shall soon be able to judge.
    I think this is one area that anomalies are not useful as any water above 80F can spawn a tropical system if other conditions are favorable.

  18. Well, when your forecast covers nearly half of the historical range, it certainly increases the likelihood of being “right.” I’d drop it a couple of notches, however, down to 5-12 in order to get into the historical average range, and expect to do pretty well with my forecast this year. Bookmark this. 🙂

  19. AccuWeather here:
    http://www.accuweather.com/blogs/news/story/35356/any-hurricane-before-august-15.asp
    … has a chart (2nd one) that all should look at. Today is the 12th. Hurricane frequency historically ramps up after mid-August. Not before. What has happened up to now is of little concern. The next six weeks will a watch and learn opportunity. Almost as much excitement as watching ice melt, grow, break apart, and drift.
    BTW, the ice island story and its threat to modern civilization was printed in our local paper. Buried in the text was a comment about how this might take 2 years to appear but the headline and first few paragraphs presented it as a terrible tragedy about to happen.

  20. John F. Hultquist
    Thanks for the accuweather link. I see a couple of things there I don’t like. This map says that the sharpest increase is Aug 20 – Sep 11, but the graph shows that the sharpest increase is in the first half of the August.
    http://vortex.accuweather.com/adc2004/pub/includes/columns/newsstory/2010/400x266_08111724_page.jpg
    The other thing that bothers me is that while actual hurricanes don’t ramp up until late August, tropical storms normally ramp up earlier. We are not seeing that this year.

  21. Thanks, Tom in Florida, but I am still not satisfied. Surely, Dr Klotzbach is aware of what you write. I would have thought his forecast took into account ALL factors. If there are important factors Dr. Klotzbach cannot know about, then his forecast cannot be very much good.
    I still feel that, if Dr. Klotzbach’s forecast has any validity, then there should be a high probability that, once a storm starts developing, it should not just peter out, as all the recent events have. But maybe these are just idle thoughts of an idle fellow.

  22. Ian W says:
    August 12, 2010 at 6:36 am

    Perhaps we are seeing a change in ocean and atmospheric behavior toward behavior that has not been seen for more than a century.

    Probably not. As far as Atlantic tropical storms go, the satellite era can be divided into pre-1995 and later. Later is behaving similarly (potentially very active) to the late 1930s to mid 1950s, the Klotzbach/Gray forecasts always have a lot to say about that division and the flip in the THC/AMO circulation.

    This could explain the failure of the UK Met Office to get things right over the last few years.

    They’d do better if they admitted that climate can cool without a decline in CO2.

  23. Well as to that ice island and the catastrophe it is going to cause with sea level rise; I haven’t noticed the water level in my toilet change yet but whent he splash gets here, I’ll let you know.
    I’m betting that the 20 foot sea level rise won’t happen this year. How is that big island going to make it around the corner of that Fjord, and get out into the shipping lanes ? It’ll be a whole United States of Deniersland by the time it gets out of that bottlrneck.
    Meanwhile if somebody offers you a free ticket on a boat called Titanic; tell them you are off to watch the Hurricane Season in Florida. Come to think of it; the Hurricanes haven’t been doing too well for several seasons now; probably because my Professor friend there retired up North of Atlanta.

  24. stevengoddard says:
    August 12, 2010 at 11:52 am

    John F. Hultquist
    Thanks for the accuweather link. I see a couple of things there I don’t like. This map says that the sharpest increase is Aug 20 – Sep 11, but the graph shows that the sharpest increase is in the first half of the August.
    http://vortex.accuweather.com/adc2004/pub/includes/columns/newsstory/2010/400x266_08111724_page.jpg

    I don’t like that graph – hand drawn. I think this from Wunderground is better and shows both TSes that do and don’t reach hurricane strength.
    http://www.wunderground.com/hurricane/history/peakofseason.gif
    Draw a line through today, and compare area to the left and right – we have a ways to go before the climatological peak.
    The graph is from their first look at the 2006 season.
    http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=365

  25. “2010 hurricanes are right at the 1944-2005 average of one for the date.”
    When are we going to see an approved list of ‘average’ year ranges?
    We keep being told that 30 consecutive data years is necessary for a valid ‘average’ but many ‘scientists’ seem to use a variety of time periods both shorter and longer than this. Is this only because it fits their meme?
    If there are no standards there is chaos and perhaps that is why so many people are convinced (or confused) one way or the other regarding AGW.
    It would not appear that any of the international bodies (e.g., WMO, IPCC, ISO) involved in this debate are setting any baselines for measurements, comparisons and the like.
    Personally, I think that 30 years is far too short to see all of the patterns possible in our climates and anyone using such a short period should be making copious declarations that their results, hypotheses, conjectures, etc have a large margin of error.

  26. From the Monthly Weather Review, August, 1903
    http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1903.pdf
    1. The hurricanes in August are formed, generally to the eastward, very near the Cape Verde Islands. At first they move westward and a little northward, and in the neighborhood of the Windward Islands, pursue a west-northwest direction. The recurve is generally effected by these hurricanes within a zone between the meridians of New Orleans and Puerto Plata, and between 29 to 33 of north latitude.
    2. The hurricanes of September originate between Barbados and St. Thomas. The recurve ia generally effected between the meridians of Cape Masi (74 W.) and the State of Texas,between the 27 and 29 of north latitude.
    3. The hurricanes of the first decade of October sometimes form in the Windward Islands, or in the eastern part of the Caribbean Sea. These recurve between 23 and 26 of north latitude, in a zone limited by the meridians of Matanzas (82 W.) oud Cape Catoche (88 W.) They come very close to Cuba pass through the western provinces, or the Yucatan Channel.

  27. re: Jim Cripwell (August 12, 2010 at 1:53 pm )
    Long term forecasts are general in nature and based on historic climate conditions that are expected to develop during the hurricane season. Individual storms are affected by the specifics of local weather. Since one cannot predict the specifics of local weather very far in advance it is impossible to say which particular tropical depressions will or will not evolve into hurricanes very far in advance. Once forecasters get a handle on the local environment of a specific tropical depression, they are pretty accurate in assessing the probabilities of further development.

  28. Ian W says:
    August 12, 2010 at 6:36 am
    Perhaps we are seeing a change in ocean and atmospheric behavior toward behavior that has not been seen for more than a century. All the clever little statistical tools like ‘Nino 3.4′ and such metrics were useful during the early part of the relatively predictable satellite era but the chaotic climate system is perhaps ponderously moving out of that eddy into a different state. All the clever statistical pattern matching may suddenly cease to work. This could explain the failure of the UK Met Office to get things right over the last few years.
    ====================================
    Well said.
    As always, too, Goddard is onto something.
    Something seems to be overwhelming the signal here.
    Epic cooling in the Pacific.
    We notice the temps above 80 degrees north are falling below freezing weeks before normal.
    And I notice the 540 thickness is starting to show up in south central Canada over the next few days…the GFS, NAM, and ECMWF all showing it.
    However, the huge upper level low over the Azores that has been blasting the Atlantic with shear….seems to be kicking out.
    http://www.ssd.noaa.gov/eumet/neatl/flash-wv.html
    Time will tell if it will be replaced with that subtropical ridge shown on Steve’s map.
    And the common sense approach of studying patterns of either intensification [which we have not seen in along time] and patterns of decay and petering out [which we have seen alot lately] has ALOT OF MERIT.
    On a local level, we were under a very high risk for severe thunderstorms today….but there must been a bubble of stable air above us.
    You could watch the petering out, with each storm, on radar.
    So regardless of the dire forecasts, they all ended in a whimper.
    Much like the hurricane season so far.
    But remember, the synoptic setup favorable for them, can change very quickly.
    We’ll see. As a coastal resident, I hope Steve’s instincts are correct!
    Chris
    Norfolk, VA, USA

  29. stevengoddard says:
    August 12, 2010 at 6:06 pm

    From the Monthly Weather Review, August, 1903
    http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1903.pdf

    No hurricanes in June or July? I like it! 🙂 The main reason the Cape Verde storms don’t happen until August or so is the water generally is too cool before then. Earlier storms tend to form in the Carribbean and Gulf of Mexico and often don’t have the space to reach major storm status.
    Really late storms sometimes track east through the Carribbean. Weird.
    So they used “recurve” in 1903, heh? One thing I’ve never figured out why storms “recurve” especially if they haven’t “curved” before.

  30. And I am asking questions too.
    Was just reading the implications of your questions being asked here.
    And the “petering out” pattern as you have shown in this post from one NHC advisory, to another [for those of us who pay attention to the patterns] does not fall on deaf ears.
    Point taken.
    Chris
    Norfolk, VA, USA

  31. Enneagram says:
    August 12, 2010 at 5:41 am

    Randomness/Chaos exists only in the mind of the beholder.

    When the frequency of hurricanes in any given year cannot be distinguished from a stochastic process (ie a Poisson distribution) then one is entitled to say “prediction is a waste of time”.

  32. If the Spanish were building another Armada this year, I’d bet on the Brits to do what they did last time (along with a lot of help from Mother Nature) . Rememeber Spain, don’t cut your anchors the way you did last time.

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