Tuesday, April 03, 2007

Colorado Gurus Up '07 Hurricane Forecast

Colorado State University tropical storm gurus Phillip J. Klotzbach and Dr. William Gray have increased the number of predicted hurricanes, named storms, and storm days for the coming 2007 tropical storm season. In their traditional April forecast they write --
We estimate that 2007 will have about 9 hurricanes (average is 5.9), 17 named storms (average is 9.6), 85 named storm days (average is 49.1), 40 hurricane days (average is 24.5), 5 intense (Category 3-4-5) hurricanes (average is 2.3) and 11 intense hurricane days (average is 5.0). The probability of U.S. major hurricane landfall is estimated to be about 140 percent of the long-period average.
That represents a substantial number of additional hurricanes when compared with their earlier December predictions.

Forecast Parameter and 1950-2000

Climatology (in parentheses)

Issue Date

8 December '06

Issue Date

3 April '07

Named Storms (NS) (9.6)



Named Storm Days (NSD) (49.1)



Hurricanes (H) (5.9)



Hurricane Days (HD) (24.5)



Intense Hurricanes (IH) (2.3)



Intense Hurricane Days (IHD) (5.0)



Accumulated Cyclone Energy (ACE) (96.2)



Net Tropical Cyclone Activity (NTC) (100%)



The culprit behind the increased hurricane chances appears to be mostly El Niño, who has once again disappeared -- as he did in 2004-05.
We have increased our forecast from our early December prediction due largely to the rapid dissipation of El Niño which has occurred over the past couple of months. Currently, neutral ENSO conditions are observed. We expect either neutral or weak-to-moderate La Niña conditions to be present during the upcoming hurricane season. Tropical and North Atlantic sea surface temperatures remain well above their long-period averages.
* * *
The weak to moderate El Niño event that rapidly developed during August to October 2006 has now dissipated.
The boys from Bighorn country continue to stubbornly insist they see no evidence that global warming has "increased hurricane frequency or intensity in any of the globe’s seven tropical cyclone basins, except for the Atlantic over the past twelve years." But they do acknowledge "global surface temperatures have increased over the last century and over the last 30 years." From the viewpoint of Colorado Springs, it's not the warming, it's the salinity.

In fact, they say, "Between 1966 and 2003, US major hurricane landfall numbers were below the long-term average." In other words, their view is that a "normal" hurricane season is considerably more violent than anything experienced in the memory of a majority of living Floridians.

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