Hurricane activity could be ‘near record’

NOAA’s forecasts up to 14 hurricanes

TOPhurricaneLEAD

Although it hedged its bets by
using a wide range, the US National Oceanic and Atmospheric Administration
Climate Prediction Center on Thursday forecast a busier than average 2010
Atlantic hurricane season.

The range of 14 to 23 named storms
and 8 to 14 hurricanes represents above average activity even at the low end of
the forecast range. 

“The 2010 Atlantic hurricane season
outlook primarily reflects an expected set of conditions during peak months –
August through October – of the season that is very conducive to increased
Atlantic hurricane activity,” the outlook report stated.

If the hurricane season produces
anywhere near the upper end of the range, coastal areas in the Atlantic basin
could be in for a rough year.

“If this outlook holds true, this
season could be one of the more active on record,” said Jane Lubchenco,
under-secretary of commerce for oceans and atmosphere and NOAA administrator. “The
greater likelihood of storms brings an increased risk of a landfall. In short,
we urge everyone to be prepared.”

The low end of the range is very
similar to the 7 April numbers issued from noted Colorado State University
hurricane forecasters William Gray and Phil Klotzbach, who predicted 15 named
storms and eight hurricanes.  Those numbers
are expected to increase when the duo release an updated forecast next
Wednesday.

“The numbers are going to go up
quite high,” Mr. Gray said Wednesday. “This looks like a hell of a year.”

The Climate Prediction Center also
forecast three to seven major hurricanes of Category 3 or higher, which means
with sustained wind speeds of 111 miles per hour or above.  The 2005 hurricane season featured seven
major hurricanes, a record four of which reached Category 5 strength with
sustained winds of at least 156 mph.

Reasons

Part of the reason for the
increasingly gloomy forecast is the sudden collapse of El Niño, which is an
anomalous warming of sea surface temperatures in the equatorial Pacific Ocean.
The phenomenon causes upper atmospheric wind shear in the Atlantic Basin,
something that hinders hurricane formation and strengthening.  Last year’s mild hurricane season was largely
attributed to El Niño. 

Although El Niño has been forecast
to subside this year, it was not supposed to happen until late this summer, and
then only transition into what is known as an El Niño neutral condition.  However, over the past couple of months, El
Niño has faded quickly and is already transitioning into a neutral state.  Forecast models are increasingly predicting
it will transition all the way into a La Niña state by the time the peak part
of the Atlantic hurricane season arrives in mid-August. The Climate Prediction
Center pointed out that La Niña contributes to reduced vertical shear over the
western tropical Atlantic.  But even if
the El Niño/Southern Oscillation neutral condition remains, the lack of
inhibiting factors from El Niño can produce a very active Atlantic hurricane
season when other conditions known to promote tropical cyclone formation are
present.  

The record-breaking 2005 hurricane
season, in which there were 28 storms and 15 hurricanes, had an El Niño that
quickly collapsed and gave way to an El Niño/Southern Oscillation neutral
condition during the hurricane season.

In addition to the collapse of El
Niño, NOAA cited record-high sea surface temperatures in the area of the
Atlantic Ocean where most tropical cyclones form, known as the Main Development
Region.  Not only are the sea surface
temperatures in the region at record highs now, they were also at record highs
in March and April.  One of the causes of
the higher sea surface temperatures is a pronounced weakening of north-easterly
trade winds, a pattern which is generally expected to continue through the
hurricane season.

A third factor cited by NOAA to
support its busy hurricane season forecast was the continuation of a
multi-decadal period of high activity in the Atlantic Basin. This period, which
began in 1995, is expected to continue this year.

Chances

The Climate Prediction Center also
forecast the hurricane season in terms of percentage chances. The outlook calls
for an 85 per cent chance of a above-normal hurricane season in terms of
activity, with a 10 per cent chance of a nearly normal season, and only a 5 per
cent chance of a below normal season.

With respect to Accumulated Cyclone
Energy, an index which accounts for intensity and duration of named storms and
hurricanes, the outlook forecast a 70 per cent chance that the 2010 season
would range between 155 per cent and 270 per cent of the median.  Any value above 175 per cent is considered
and extremely active, or hyperactive, hurricane season.

TOPhurricaneSTORY

Hurricane Dean hit Cayman in August 2007.
Photo: File
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