Predicting hurricane track has improved

Thanks to improved technology,
forecasters have a
better idea of where hurricanes
will go, but still need
help predicting how hard
they will blow.

John Cole, the warning
communication technologist
at the National Weather Service
in Newport, said the use
of multiple models has enabled
forecasters to refine areas
along the coastline where
storms are projected to come
ashore and pinpoint areas to
place under storm watches or
warnings.

“By using an ensemble of
models, we’ve cut our track
errors in half,” said Cole,.
“Being able to better refine
areas of watch and warning
along the coastline and decrease
coastal evacuations,
which is very costly, has been
improving.”

However, intensity forecasts
— figuring out how
storms intensify and
strengthen — have not improved
measurably, Cole said.
The strength of a storm can
still change without warning.

“There continues to be intensity
errors — that’s why
that’s where a lot of the research
and funding is going,”
he said. “Hurricane Alex
went from a tropical storm
to a Category 2 very quickly,
which caused big problems
for us.”

With all indications pointing
to a very active hurricane
season, Cole said The National
Hurricane Center implemented
some changes that
took effect May 15.

“We are now issuing a fiveday
forecast for tropical cyclones;
it used to be three
days,” he said.

He said the size of the
“cone of uncertainty” —
the visual aid used in hurricane
forecasting of the track
that balloons outward from
a storm’s current position —
will be smaller and will no
longer have the “the skinny
black line” in the center.

“We don’t want people to focus
on that forecast track because
67 percent stay within
that cone track and 33 percent
go outside,” Cole said.

Cole said the National Oceanic
and Atmospheric Administration
has focused on
better estimating storm surge
and has improved its predictions
over the last few years
with the help of various measurements,
including LiDAR
data, which provides ground
elevation, and Geographic
Information System mapping
data. The Saffir-Simpson
Hurricane Wind Scale for
each of the five hurricane categories
no longer ties specific
storm surge and flooding effects
to each category.

“Differences in topography
cause different surges along
the coastline,” he said.
He said forecasters are
looking at the worst case scenarios
for storm surge —
based on that data as well as
the movement, speed and direction
of a storm — so they
can relay this information to
local emergency management
people within 36 hours of projected
landfall.

“And we’re looking at implementing
specific storm
surge watches or warnings in
the future,” he added.
Cole said other improvements
have been made to
some of its text and geographical
products.

For example, the Public Advisory
will be organized into
sections that contain keywords
to assist the human
eye and computer software
to help find specific information.

The summary section of
the advisory will move to the
top and contain more information.

Watch and warning
information will be organized
in list or bullet form.
In addition, a summary section,
like the one in the Public
Advisory, will be added
to the Tropical Cyclone update
when information changes
from the previous advisory.

And the National Weather
Service and National Weather
Hurricane Center will use the
term “post tropical” to refer
to any system that no longer
possesses the characteristics
of a tropical cyclone.

“We are always looking at
the best way to convey information
to the public,” he said.

The reconnaissance aircraft
used by the Hurricane Hunters
has been upgraded from
the C-130 Hercules to the

C130J Super Hercules, said

Dr. Richard Pasch, the senior
hurricane specialist at the
National Hurricane Center in
Florida.

With two external fuel
tanks the J-model flies faster
and higher, flies farther at a
higher cruise speed and takes
off and lands in a shorter distance,
according to the Hurricane
Hunters Association
website.

Pasch said the plane is
equipped with state-of-theart
navigational systems including
a global positioning
system.

The GPS Dropsonde, which
is launched from the aircraft,
provides an array of valuable
information, he said.

“The Dropsonde measures
winds and gives us a
better estimate of intensity,
the extent of the tropical
storm force winds and the extent
of outermost storm force
winds,” he said.

In 2008 planes were
equipped with a stepped frequency
microwave radiometer,
known as a SFMR, which
is attached to the wing to
help determine surface wind
speeds, Pasch said.

“These are two very important
instruments that provide
us with invaluable information
— in fact information
from the Dropsonde was the
basis for us upgrading Hurricane
Andrew from a Category
4 to a Category 5 hurricane,”
he added.

With the more sophisticated
equipment giving researchers
a better idea of
how a storm will behave, scientists
say they can pass that
information on to the public
even earlier. Tropical storm
and hurricane watches will
be issued 48 hours in advance
and tropical storm and hurricane
warnings will be issued
36 hours in advance — both
times are 12 hours earlier
than in previous years, Cole
said.

That 12-hour head start
will be very helpful, said
Norman Bryson, the assistant
director of Onslow
Emergency Services and
Homeland Security.

“The more information,
the earlier, the better off you
are,” he said. “Earlier help
with the forecast gives us longer
to plan how we’re going
to handle it.”