Predicting the Weather on the Rhythm Method

...officially because the Church of Dear Leader sez so.

The NOAA released its annual hurricane season predictions last week.

As Thomas Crowley points out at RealClimate, along with its now-standard explanation that there is a natural cycle of multidecadal (40-60 year) length in the North Atlantic circulation (often referred to as the "Atlantic Multidecadal Oscillation"--see Figure), that is varying the frequency of Atlantic tropical cyclones, and that the present high level of activity is due to a concurrent positive peak in this oscillation.

Which is true, as Crowley points out- and which is also likely exacerbated by the global warming conditions.

The NOAA's press release cited above says:

..."For the 2006 north Atlantic hurricane season, NOAA is predicting 13 to 16 named storms, with eight to 10 becoming hurricanes, of which four to six could become 'major' hurricanes of Category 3 strength or higher," added retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator...

Warmer ocean water combined with lower wind shear, weaker easterly trade winds, and a more favorable wind pattern in the mid-levels of the atmosphere are the factors that collectively will favor the development of storms in greater numbers and to greater intensity. Warm water is the energy source for storms while favorable wind patterns limit the wind shear that can tear apart a storm's building cloud structure.

This confluence of conditions in the ocean and atmosphere is strongly related to a climate pattern known as the multi-decadal signal, which has been in place since 1995. Since then, nine of the last 11 hurricane seasons have been above normal...

I hate to bring this up to Dr. Lautenbacher, but

Global Warming Slows the Winds

By Betsy Mason
ScienceNOW Daily News
3 May 2006
Climate models predict that global warming will upset the delicately balanced atmospheric circulation that controls global climate and weather patterns. Now scientists are finding evidence that man-made greenhouse gas emissions may already be tipping the equilibrium, which could have severe repercussions, including altered weather patterns and a decline in important fishing grounds.

A key feature of Earth's atmospheric circulation is a steady flow of tropical air known as the Walker circulation. Warm air rises over the equatorial western Pacific and cools and sinks in the east. This sets up a flow of air over the ocean from high pressure in the east to low pressure in the west. The winds push water from east to west, which causes an upwelling of cold, nutrient-rich water in the eastern Pacific. Simple climate theories predict that global warming will weaken this circulation.

But is it actually happening? A team led by climate scientist Gabriel Vecchi of the U.S. National Oceanic and Atmospheric Administration examined historical weather records from the equatorial Pacific Ocean dating back to 1861. They found that the difference in pressure between the east and west Pacific has declined since that time, suggesting a weakening Walker circulation...

This was also covered in detail in a recent Nature publication (Nature 441, 73-76 (4 May 2006) | doi:10.1038/nature04744). I'm not going to go into details: it's behind their firewall and highly technical. Suffice to say it shows a steady decrease in this wind pattern over the last century.

In that same publication (although a differnt citation:Nature 441, 11 (4 May 2006) | doi:10.1038/441011a), the strife among the NOAA climate scientists is noted:

At issue is whether the historical record of cyclones is complete enough for accurate conclusions to be drawn about changes from past patterns. Many researchers called for the databases to be brought up to date by including modern assessments of past storms, including their intensities. It is a daunting task that, for now, is being done only for the Atlantic basin by Landsea and his colleagues.

Even given the gaps in the database, several new studies suggested that rising sea surface temperatures are having a noticeable effect on cyclones. Peter Webster of the Georgia Institute of Technology in Atlanta, co-author of one of last year's papers, presented data hinting that not only are hurricanes growing more intense over time, but that the length of the storm season has increased as well. Starting from 1950, he told the meeting, the storm season has grown longer in the Atlantic by about five days per decade, in the northeastern Pacific by eight days per decade, and in the northwestern Pacific by ten days per decade.

In Britain, researchers at the Benfield Hazard Research Centre in Surrey have run climate simulations suggesting that half the recent rise in hurricane activity in the North Atlantic can be explained by the observed increase in sea surface temperature in the region where these hurricanes develop. A warmer ocean would, in theory, provide more fuel for hurricanes to intensify.

And in Japan, a team has used the Earth Simulator supercomputer to run high-resolution simulations of global climate, both in today's conditions and in a world warmed by higher levels of atmospheric carbon dioxide. Preliminary results suggest that, in the latter scenario, the number of tropical cyclones would drop by about 30% worldwide. But the number would rise in the Atlantic, and storm intensity would increase worldwide (K. Oouchi et al. J. Meteorol. Soc. Jap. 84, 259–276; 2006).

Now what do you suppose the NOAA has also predicted for this summer?

The National Oceanic and Atmospheric Administration today released its 2006 east Pacific hurricane season outlook — predicting a below average season with 12 to 16 tropical storms, of which six to eight could become hurricanes, including one to three major hurricanes of category 3 strength or greater.

An average east Pacific hurricane season features 15 to 16 tropical storms, with nine becoming hurricanes, including four to five major hurricanes...

So it's nice to know even though officially NOAA is saying Al Gore is a very wrong man, and nobody should listen to Jim Hansen, the guys actually handling the data are actually looking at the data- and predicting it the way the global warming models do.