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Seasonal forecasting of tropical storms
The prediction method relies on the use of coupled ocean-atmosphere dynamical models. Due to increased complexity, such a model is run at a coarser resolution than weather prediction models and thus is unable to produce tropical storms similar to those observed in the real world.
Forecast for June to November 2012
Issued 24 May 2012
The most likely number of tropical storms predicted to occur in the North Atlantic during the June to November period is 10, with a 70% chance that the number will be in the range 7 to 13. This represents slightly below normal activity relative to the 1980-2010 long-term average of 12.
An ACE index of 90 is predicted as the most likely value, with a 70% chance that the index will be in the range 28 to 152 - which is slightly below normal relative to the 1980-2010 average of 104.
Note: Tropical Storm Alberto occurred in May and thus was outside the period covered by this prediction (June-November).
Tropical Storm Frequency Seasonal Prediction 2012
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ACE Index Seasonal Prediction 2012
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Our Climate Services for Reinsurance provide expert advice on tropical storms. A detailed report with information on probabilities and the strength and credibility of signals within the forecast for the next six months is produced each month from March to September.
Download previous reports issued in June from
2007
(PDF, 686 kB)
,
2008
(PDF, 615 kB)
,
2009
(PDF, 788 kB)
,
2010
(PDF, 2 MB)
and in May from
2011
(PDF, 2 MB)
.
To purchase forecast reports for 2012 please email consulting@metoffice.gov.uk or contact our 24-hour customer centre.
However, it is possible to identify features in the model which are indicative of tropical storms; for example, low central pressure and high relative vorticity. These features can be tracked and counted to arrive at a total number of storms for the season.
For each model storm, we also calculate the individual accumulated cyclone energy (ACE) index and total these values over the whole season to arrive at the seasonal ACE index. The ACE index is calculated as the square of the maximum wind speed for each six hourly period of the storms lifetime. The total number of model tropical storms and ACE index may differ from those values seen in the real world. To make these adjustments we use a calibration procedure based on a fixed historical period
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