Posted by: pyeager | June 18, 2009

2009 Hurricane Season Forecast

I know that the official 2009 Hurricane Season Forecast (Climate Prediction Center–CPC) was issued about a month ago, but it’s certainly topical since the busiest part of the hurricane season is typically from the second half of August through September.

I’m not a long-range forecasting expert, so I do not make long-range forecasts and don’t intend to make it sound as if blogs like this one (and the recent one on the Summer 2009 forecast and preview of the upcoming winter, Snowy, Cold Winter on the Way?) are critical of the work done by those who do. Long-range forecasting is difficult and specialized, requiring exceptional research and analysis. I will say, however, that how the forecast information is reported is critical to how it’s received, and just with the summer forecast, the hurricane forecast has problems.

The Forecast

CPC 2009 Hurricane Season Forecast

CPC 2009 Hurricane Season Forecast

The image above summarizes the key forecast information into a chart for both the Atlantic Basin and the eastern Pacific by percentage. The issuance of such a percentage forecast is something that I discussed in the blog about the summer forecast, so it shouldn’t be surprising that stating there is a 50% chance that the number of named storms in the Atlantic Basin (western Atlantic, Caribbean, and Gulf of Mexico) this season will be near normal is not a piece of information I consider to be useful. There’s also a 50% chance that the season will either be above or below normal in the Atlantic Basin.

Granted, their forecast discussion includes some of the variables that might ultimately determine whether the season will be more, or less, active than normal; however, the percentage forecast itself is not very useful.

Number of Named Storms

The forecast of the number of tropical storms (9-14), the number of hurricanes (4-7), and the number of major hurricanes (1-3)  is interesting–and it’s a way to gauge the general accuracy of the forecast–but this, also, does little to give the person living in a coastal community information to help him. Is there a bigger threat for storms in Florida, the eastern Carolinas, or Texas?

Intensity of the Season

So, what is the best method for gauging the intensity of the season? Government forecasters try to do so by the ACE Index, which is a wind energy index.  The blog ACE Index May Be Better Gauge of Seasonal Activity might help to understand it. It’s a bit convoluted, if you ask me.

While it’s an attempt at quantifying something that’s difficult to quantify, it might be simpler and better for the public if the forecast were more direct and less complicated. Instead of these large, generic forecast indicators about the season, make a forecast for each region–which areas are most likely to have storms, which areas are most likely to have major hurricanes, and what part of the season brings the biggest risk.

Some private forecasters attempt forecasts like these. They’re tougher to make, and they’re riskier because of the details.

They’re also more useful to the public.

–Paul Yeager

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