More forecasters predict active hurricane season

Various meteorological or academic
entities are joining the bandwagon in calling for an extremely active 2010
Atlantic Basin hurricane season, some even more active than predicted by
Colorado State University scientists less than three weeks ago.

The forecast of North Carolina
State University professors Lian Xie and Montserrat Fuentes, along with
graduate student Danny Modlin, calls for 15 to 18 named storms and eight to 11
hurricanes. That forecast was issued Monday.

Last week, Weather Services
International issued a forecast calling for 16 named storms, nine hurricanes
and three major hurricanes of Category 3 or above.

On 9 April, Tropical Storm Risk
issued a forecast calling for 16.3 names storms, plus or minus 4.1 storms; 8.5
hurricanes, plus or minus 2.8; and four major hurricanes, plus or minus 1.7.

On 7 April, Colorado State
University scientist Phil Klotzbach and William Gray released a forecast
calling for 15 named storms, eight hurricanes and four major hurricanes.

Several key climatology factors are
driving the active season forecasts, led by the fact that the El Niño event in
the tropical Pacific Ocean is dissipating and is predicted to shift to either a
neutral condition or to a La Niña before August, in time for the peak part of
the Atlantic hurricane season.

El Niño causes increased upper
level wind shear in the Atlantic, hindering tropical cyclone formation and
strengthening.  That wind shear dies down
during El Niño neutral and La Niña periods.

In addition, the temperatures in
the main tropical cyclone development zone in the tropical Atlantic have been
at record highs since February.

Weather Services International
Chief Meteorologist Todd Crawford said the sea surface temperatures in the
eastern and central tropical Atlantic are warmer now than they were in April of
the “freakishly active season of 2005”.

“Our forecast numbers are more
likely to rise than fall in future forecast updates heading into the season.”

In addition to the El Niño
condition and the high tropical Atlantic sea surface temperatures, trade winds
in the Atlantic are expected to remain light during the hurricane season,
allowing ocean temperatures to remain high, promoting tropical cyclone

One important undetermined variable
is the amount of West African summer rainfall. More rainfall in West Africa
acts to reduce the amount of Saharan dust that enters the atmosphere over the
tropical Atlantic. More dust acts to shield the ocean from sunlight, promoting
a cooling trend of the sea surface temperatures. As a result, more West African
rainfall promotes a more active Atlantic hurricane season.

Despite the predominance of
forecasts predicting a highly active hurricane season, not everyone is on board
with that prediction.  The Southern California
Weather Authority issued its Hurricane and Monsoon Forecast for 2010 two weeks
ago and called for a below to average Atlantic Basin hurricane season.  It predicted a large, elongated ridge to form
in the Atlantic increasing wind shear. However, it noted that some storms will
escape the shear by rounding the base of the ridge and moving into the Gulf of

“These storms will likely be the
few that cause major damage, possibly near the 1915 New Orleans hurricane
scale,” the SCWXA said.

The North Carolina professors also
see an active season in the Gulf of Mexico, with five to seven named storms and
two to four hurricanes affecting the area. 
They predict three to six of those named storms will make landfall along
the Gulf Coast, with an 80 per cent chance one will be a hurricane and a 55 per
cent change that one will be a major hurricane.

Weather Services International
forecasts an increased risk of a hurricane landfall for the Northeast US this

“Our statistical landfall forecast
model, which takes into account northern hemispheric ocean temperatures and
current atmospheric patterns, is suggesting that the coastline from the Outer
Banks to Maine is under a significantly increased threat of a hurricane this
season, relative to the normal rates, which are admittedly quite small,” said
Mr. Crawford. “Our model suggests that the threat to the Northeast coast this
season is on par with that in Florida and the Gulf coastal states.”

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