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Summer Blizzards Hurricane season 2007 forecast...


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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    This people is my 2007 Atlantic Hurricane season forecast...

    Now i was planning on doing a very detailed and long forecast, however while there will be a fair bit of detail to this forecast, i am afraid that things have come up delaying me and as a result i have decided to post now.

    This forecast will be updated on or before September 10th...

    This forecast will be split into six main areas...

    1) PDO (Pacific Decadal Oscillation)

    2) ENSO (El Nino Southern Oscillation)

    3) AO (Arctic Oscillation)

    4) QBO (Quasi-Biennial Oscillation)

    5) Sea Surface Temperature anomalies

    6) Conclusions

    Each section will contain some information about the topic and its relevance to this forecast, as well as the analogues and expected state this season...

    PDO (Pacific Decadal Oscillation)

    http://www.john-daly.com/theodor/pdotrend.htm

    The Pacific Decadal Oscillation (PDO) is a long-lived ENSO-like pattern of Pacific climate variability (Tanimoto et al., 1993; Zhang et al., 1997). ENSO (El Niño/La Niña + Southern Oscillation) and PDO have similar spatial and temperature patterns, but show a different behaviour in time. While ENSO events are inter-annual phenomena, the PDO covers decades. A full oscillation, comprising a warm and a cool phase, may extend over more than 50 years.

    The only analogues which matched the March-April period were:

    1960

    1990

    ENSO (El Nino Southern Oscillation)

    http://www.cdc.noaa.gov/people/klaus.wolter/MEI/#discussion

    El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales.

    There are many different ways to measure the state of the ENSO, however I think that the best way to measure it is by the MEI index (Multivariate ENSO Index), because it takes into account six variables, these are:

    1) Sea-level pressure

    2) Zonal and meridional equatorial winds

    3) Components of the surface wind

    4) Sea surface temperature

    5) Surface air temperature

    6) Total cloudiness fraction of the sky

    http://iri.columbia.edu/climate/ENSO/curre.../technical.html

    This is also a very important link; it is the latest update on the ENSO from IRI, and points to a 55% chance of La Nina conditions developing this summer. Also on the IRI site is this link, which gives details on what each model expects to happen and the previous La Nina and El Nino event and how the models handled that.

    http://iri.columbia.edu/climate/ENSO/curre.../SST_table.html

    This table shows that how the models handled the other two events the best, however the models were not progressive enough in bringing in or exiting the La Nina events, in my opinion, we will enter a weak La Nina during July, at that point I would back a slow strengthening and a peak during October at the top end of weak La Nina territory.

    The only analogues which matched the March-April period were:

    1994

    1979

    QBO (Quasi-Biennial zonal wind Oscillation)

    http://ugamp.nerc.ac.uk/hot/ajh/qbo.htm

    http://en.wikipedia.org/wiki/Quasi-biennial_oscillation

    The QBO is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerly’s in the tropical stratosphere with a mean period of 28 to 29 months. The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km per month until they are dissipated at the tropical tropopause. Downward motion of the easterlies is usually more irregular than that of the westerlies. The amplitude of the easterly phase is about twice as strong as that of the westerly phase. At the top of the vertical QBO domain, easterlies dominate, while at the bottom, westerlies are more likely to be found.

    For a hot summer, no state is preferred; therefore neutral values would be best to allow another teleconnection to dominate.

    The only analogues which matched the March-April period were:

    1979

    2005

    AO (Arctic Oscillation)

    http://www.cpc.noaa.gov/products/precip/CW..._index/ao.shtml

    The AO is effectively a measure of pressure at northern hemisphere high latitudes, with 1010mb to 1015mb being the thresholds for neutral values, the AO is a stratospheric teleconnection, meaning that observations are made in the upper atmosphere to define the AO value each day.

    The only analogues which matched the March-April period were:

    1986

    1994

    Sea surface temperature anomolies

    sst_anom.gif

    As you can see, across the Tropical Atlantic, anomolies are below average in the east but above average in the west and Carribean, this means that while the number of waves coming of Africa may be low, any storms which do develop may be strong.

    Conclusions

    Based on the anologues below, and the fact that sea surface temperature anomolies are supportive of any waves west of 40 degrees east to develop, here are the statistics and maps relevant to this forecast...

    1990

    1994

    2005

    16 to 18 named storms...

    6 to 8 hurricanes...

    2 to 4 major hurricanes...

    Average number and how this season will compare...

    9 to 11 named storms... (+7)

    5 to 7 hurricanes... (+1)

    2 to 4 major hurricanes... (+/-0)

    post-1806-1181420514_thumb.png

    As you can see, for the first half of the 2007 atlantic hurricane season, lanfall in Florida and the Gulf Coast is favoured...

    post-1806-1181420701_thumb.png

    As you can see, for the second half of the 2007 atlantic hurricane season, recurviture away from the USA mainland is favored...

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    Posted
  • Location: Liphook
  • Location: Liphook

    Very detailed forecast SB and really I do agree with most of it. I won't comment on the storm tracks given thats always gonig to be hit and miss depending on the exact set-up and other factors however I do strongly agree with most of what your saying, I can see a very active season as you are forecasting, tohugh i think with La Nina strengthening and already the Atlantic basin below average for shear (If La nina does form this will only continue to drop further below average) therefore my hurricane range would be a touch higher, say 7-9 and my majors 4-6.

    Also the only other question mark has to be the use of 94 as a ENSO analogue. While it may be close right now the two years clearly are going down a different route. The 94 season saw a El Nino develop much like 06 (and in fact was nearly identical to the 06 El nino!) and we was still in a 4 year El nino phase which resulted in the strong El nino in 92 and the mod one in 94/95, where as this season is heading nito a La Nina. i think you'd have been better to compare La Nina summers/Autumns rather then the March-April, which is far enough out from the masin chunk of the season that quite a large change can occur and make the seasons unable to be analogues anymore.

    Just a quick question, what hurricane seasons did we see a weak La nina in the summer and autumn??

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
    Very detailed forecast SB and really I do agree with most of it. I won't comment on the storm tracks given thats always gonig to be hit and miss depending on the exact set-up and other factors however I do strongly agree with most of what your saying, I can see a very active season as you are forecasting, tohugh i think with La Nina strengthening and already the Atlantic basin below average for shear (If La nina does form this will only continue to drop further below average) therefore my hurricane range would be a touch higher, say 7-9 and my majors 4-6.

    Also the only other question mark has to be the use of 94 as a ENSO analogue. While it may be close right now the two years clearly are going down a different route. The 94 season saw a El Nino develop much like 06 (and in fact was nearly identical to the 06 El nino!) and we was still in a 4 year El nino phase which resulted in the strong El nino in 92 and the mod one in 94/95, where as this season is heading nito a La Nina. i think you'd have been better to compare La Nina summers/Autumns rather then the March-April, which is far enough out from the masin chunk of the season that quite a large change can occur and make the seasons unable to be analogues anymore.

    Just a quick question, what hurricane seasons did we see a weak La nina in the summer and autumn??

    Thanks, what i was planning to do was examine each teleconnection and find out what state it was in for each season, however it is very time consuming and as a result, i had to simplify my forecast somewhat, a lot of what i posted above is actually snipets from my summer forecast.

    On the subject of 1994, were it just El Nino, then i would agree with you, however it is also an anologue for the AO and i did think about rolling forward my anologues, however i decided to see how close this forecast was to reality.

    Because i was going to study each teleconnection in detail, while i do not know which Autumns were classed as La Nina, since 1990, only 1999 was over the weak La Nina threshold for summer as a whole, there were 8 El Nino summers and 8 neutral summers since that time.

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    • 2 months later...
    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Here is my reveiw of the hurricane season so far, assuming that no more named storms form before September...

    So far we have had 5 named storms form, this is bang on average for the current timeframe, however what we have seen are some inhibiting factors which have killed off most waves, despite the only hurricane of the season as yet, being a monster category 5 at landfall, in my opinion, these inhibiting factors have been...

    1) Cool sea surface temperature anomolies in the eastern Tropical Atlantic have led to subsidence and dry air, because of this, waves east of 50W have found there convection waning...

    2) Strong QBO values have caused abnormally strong upper level easterlies, especially in the eastern Atlantic, thus, many waves have been unable to establish a low level circulation...

    Despite this, the advantage of this season has been the synoptic setup, because of strong subsidence and high pressure east of 50W, many waves struugle to reach 10N, meaning that when they do develop and are allowed to gain lattitude (Dean), they take one of the best paths for rapid development...

    My forecast update will be out in the next few days...

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    • 5 months later...
    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Prediction in June...

    16 to 18 named storms...

    6 to 8 hurricanes...

    2 to 4 major hurricanes...

    Actual numbers...

    15

    6

    2

    I don't mean to blow my own trumpet, but i would say that i made a dam good long range forecast of the hurricane season.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
    well if you think you are as good as you say you are why don't you have a go at that hurricane competition?

    I will be doing, however we have a very unusual pattern at the moment, specifically over the Arctic, and so with no duo-monthly anologues available for the AO, i am waiting until the February data is in before issuing a prediction, so around mid-March.

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    Posted
  • Location: Derby - 46m (151ft) ASL
  • Location: Derby - 46m (151ft) ASL
    Prediction in June...

    16 to 18 named storms...

    6 to 8 hurricanes...

    2 to 4 major hurricanes...

    Actual numbers...

    15

    6

    2

    I don't mean to blow my own trumpet, but i would say that i made a dam good long range forecast of the hurricane season.

    Just a thought SB, and out of pure interest, how many named storms/hurricanes/major hurricanes happen each year on average?

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    Posted
  • Location: Kilmarnock, Scotland
  • Location: Kilmarnock, Scotland

    Hi Chris, I have has a look back through the last 10 years and the average is as follows;

    Named Storms: 15

    Hurricanes: 8

    Major Hurricanes: 4

    I do not have the information readilt available to go back further.

    Hope that is helpful.

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    Posted
  • Location: Liphook
  • Location: Liphook

    My call was a little to high on the hurricanes and majors though the lower end wasn't stupidly far away and my tropical storm call on another forum was 16 so only one off based on the current estimates.

    Anyway good call SB lets see if you can do it again in the comp!

    If i was to make an early call it'd be 13/9/5...tropical storms could be a little lower but there wil lbe more hurricanes/majors this year I suspect...my anolouges probably 1950, 1971 and 1999 right now.

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