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Last Updated: Feb 13, 2017 - 1:45:37 AM |
NOAA
(National Oceanic Atmospheric Administration) has finally released
their 2015 North Atlantic Hurricane Season Outlook: NOAA is predicting 6
to 11 named storms (winds of 39 mph or higher) in the North Atlantic,
of which 3 to 6 could become hurricanes, including 0 to 2 major
hurricanes...NOAA is predicting that along the North Atlantic, there
will be a 70 percent likelihood of six to 11 named storms (winds of 39
mph or higher), of which between three and six could become hurricanes
(winds of 74 mph or higher). At most, two of those are expected to
become major hurricanes, defined as Category 3, 4 or 5, characterized by
winds of 111 mph or higher. Like the other governing bodies hurricane
season outlooks, they are also going for a below average season. This
outlook is forecast to be dominated by effects of the strengthening El
Niño conditions.
"The main factor expected to suppress the
hurricane season this year is El Niño, which is already affecting wind
and pressure patterns, and is forecast to last through the hurricane
season," said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with
NOAA's Climate Prediction Center. "El Niño may also intensify as the
season progresses, and is expected to have its greatest influence during
the peak months of the season. We also expect sea surface temperatures
in the tropical Atlantic to be close to normal, whereas warmer waters
would have supported storm development."
The hurricane impacts of
El Niño and its counterpart La Niña are like a see-saw between the
Pacific and Atlantic oceans, strengthening hurricane activity in one
region while weakening it in the other. El Niño is a cyclic climate
phenomenon that involves both the ocean and the atmosphere. One of its
hallmarks is warmer-than-average sea-surface temperatures in the
tropical Pacific Ocean. Although the El Niño fizzled last winter, the
pool of warm water stuck around this spring and strengthened into a
full-blown event. In El Niño years, the wind patterns are aligned in
such a way that the vertical wind shear is increased over the Caribbean
and Atlantic. The increased wind shear helps to prevent tropical
disturbances from developing into hurricanes. whereas, the opposite
applies in the eastern Pacific, the wind patterns are altered in such a
way to reduce the wind shear in the atmosphere, contributing to more
storms.
From experience when many Bahamians hear 'below average
season' they tend to let their guards down because they think 'below
average' means no hurricanes this year for them and tend to prepare
less. Keep in mind that While a below-normal season is likely in
Atlantic, there is still a 10 percent chance of an above-normal season.
A below-normal season doesn't mean we're off the hook or we will be
spared. As we've seen before, below-normal seasons can still produce
catastrophic impacts to The Bahamas. Sadly, one notable example of this
was the 1992 season in which only seven named storms formed, yet the
first was Andrew - a very powerful Category 5 Major Hurricane that
devastated The Bahamas and left a staggering $250 million dollars in
damage to The Bahamas alone and over $26.5 Billion in the state of
Florida. It's been 10 and 11 years respectively since the historic 2004
and 2005 hurricane seasons, when three hurricanes Frances, Jeanne and
Wilma devastated the island of Grand Bahama, leaving millions of dollars
in damage and the economy of Grand Bahama in disarray. It is fair to
say that even to this day, the economy of Grand Bahama has still not
fully recovered from those hurricanes.
This season's first storm,
Tropical Storm Ana which formed on May 8 and came ashore in the
Carolinas earlier this month, bringing rain from Virginia to South
Carolina. It did not cause any major problems.
Why we forecast a below average 2015 North Atlantic hurricane season:
The forecasters cited the following main factors that will influence the coming season:
1) The current borderline weak/moderate El Niño event is expected to
persist or intensify during the 2015 hurricane season. El Niño events
tend to suppress Atlantic hurricane activity in three ways:
- By creating high levels of wind shear over the tropical Atlantic, which tends to tear storms apart.
- By increasing sinking motion and high pressure over the tropical Atlantic.
- By making the air more stable over the tropical Atlantic.
2) Near-average sea surface temperatures (SSTs) are in place over the
hurricane Main Development Region (MDR), from the Caribbean to the coast
of Africa between between 10°N and 20°N. These SSTs are expected to be
near or below average during the peak August - October portion of
hurricane season, and are expected to be cooler than SSTs in the
remainder of the global tropics (SSTs in the remainder of the global
tropics were 0.31°C warmer than SSTs in the MDR in May.) This
configuration of SSTs is often quite hostile to Atlantic tropical
cyclone development.
3) The active period of hurricane activity
that began in 1995 due to a natural decades-long cycle in hurricane
activity called the Atlantic Multi-decadal Oscillation (AMO) may now be
over. The SST pattern associated with that cycle is absent this year,
and NOAA said: "There have been two seasons in a row, 2013 and 2014,
with below-normal and near-normal activity respectively and neither had
an El Niño event responsible for the reduced activity. The current
configuration of SSTs in the Atlantic Ocean, both in the MDR and the
entire North Atlantic, are suggestive that the AMO may no longer be in
the warm phase."
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