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Graphical Tropical Weather Outlook

Updated 3 March 2009


  1. Overview
  2. Changes for 2009
  3. Explanation of the Graphical TWO
  4. Probabilistic Genesis Forecasts
  5. Methodology
  6. Availability
  7. Examples
  8. Potential Benefits of a Graphical TWO
  9. References

2. Changes for 2009

  1. The 2009 version of the GTWO will once again include a three-tiered, color-coded, categorical genesis forecast for the next 48 hours. However, the probabilities assigned to the color-coded bins have been adjusted to reflect the latest verification from the 2008 hurricane season. The following categorical bins will be used in 2009:

    • Low:  Probability of genesis less than 30%

    • Medium:  Probability of genesis from 30-50%

    • High:  Probability of genesis greater than 50%

  2. The NHC is eliminating the Special Tropical Disturbance Statement (DSA) that was issued when important changes with areas of disturbed weather had occurred since the previous issuance of the TWO. In lieu of the Special Tropical Disturbance Statement, the NHC will now issue special text and graphical TWOs when significant changes have occurred. The Special TWO will be issued under the same product headers and will replace the previously issued regular or special graphical and text TWO.

Next:  Explanation of the Graphical TWO

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Page last modified: Monday, 16-Mar-2009 14:26:37 UTC