Monstrous
super typhoon Usagi holding its own, Hong Kong braces for possible
impact
This image was taken by the Japan Meteorological Agency’s MTSAT-2 satellite at 0730Z on September 20, 2013. (NOAA)
21
September, 2013
Super
typhoon Usagi, 2013′s strongest storm on the planet, may have
peaked in intensity, but remains an extremely dangerous cyclone as it
continues on a collision course with southern Taiwan and, likely,
Hong Kong.
The
Joint Typhoon Warning Center says Osagi’s maximum sustained winds
are 150 mph, the equivalent of a category 4 hurricane. That’s
down from at least 160 mph Thursday (category 5 level). But this is a
mammoth storm, tropical storm force winds span 275 miles across it.
On
Thursday evening, a
satellite-based estimate of its minimum pressure was
an astonishingly low 882 mb, which would have made it the deepest
and most intense storm to exist on Earth since 1984 (tied with
hurricane Wilma in 2005).
Look
at this incredible high resolution satellite image of the storm from
Thursday afternoon, revealing the textbook traits of a flawless
cyclone:
Usagi
infrared satellite view 12:33 p.m. ET Thursday (Colorado State
University)
You
see the cloud-free, distinct eye which is surrounded by tall
thunderstorms on all sides.
Due
to a re-arrangement of its internal structure since that time, known
as an eye-wall
replacement cycle,
Usagi has lost some steam and its satellite presentation – while
impressive – is less than perfect.
Usagi
infrared satellite view 1:14 p.m. ET Friday (NOAA)
Its
eye is somewhat ragged, and deep convection (a fancy term for
thunderstorms) is less pronounced in its northeast quadrant.
What’s
next for Usagi?
The
Joint Typhoon Warning Center predicts additional weakening as Usagi’s
circulation is disrupted by Taiwan. Usagi will batter Taiwan’s
south and east coast with damaging winds, torrential range, massive
waves, and a dangerous storm surge today into Saturday. The storm’s
rain bands have already begun to lash coastal areas.
Usagi
is then expected to cross the South China Sea, but further weakening
is forecast.
“THE
SYSTEM IS UNLIKELY TO RE-INTENSIFY OVER THE SOUTH CHINA SEA DUE TO
LAND INTERACTION AND DECREASING OCEAN HEAT CONTENT,” saysthe
Joint Typhoon Warning Center.
Usagi
forecast track (Joint Typhoon Warning Center)
The
storm could potentially come ashore near Hong Kong late Sunday local
time (Sunday morning EDT). Confidence in the overall track is high
but small deviations could push the brunt of the storm to Hong Kong’s
northeast or southwest.
“Usagi
is still far away from Hong Kong,” writes
the Hong Kong Observatory.
“As there may still be changes to its track, its effects on Hong
Kongs weather can be vastly different. Usagi is a mature tropical
cyclone and may become the strongest storm affecting Hong Kong since
this year. The public should remain vigilant, pay attention to the
latest weather report, and take precautions against strong winds and
flooding as early as possible.”
The
Joint Typhoon Warning Center predicts Usagi will have maximum
sustained winds near 100 mph around the time it would potentially
make landfall in or near Hong Kong. If a direct hit were to occur,
the storm would also produce copious amounts of rain and, depending
on the angle of approach, potentially a devastating storm surge
(given the storm’s size and intensity).
Hong
Kong’s typhoon history
Direct
and indirect hits from typhoons or tropical storms are very common in
Hong Kong, happening annually – almost without exception and often
on multiple occasions.
As
the city, populated by 7.1 million residents, has considerable
experience with these storms, it is usually well-prepared and has
avoided mass casualties from recent events. Since 1990, 74 named
storms have affected Hong Kong with about 44 total fatalities (based
on data
from the Hong Kong Observatory).
Not since 1983, when Ellen claimed ten lives, has Hong Kong
experienced a death toll in the double digits from a tropical storm
or typhoon.
Number
of people killed or missing from named storms to impact Hong Kong
from 1960-2011 (Hong Kong Observatory)
In
the more distant past, 15,000 and 11,000 lives were lost in storms
that devastated Hong Kong in 1906 and 1937, notes a blog post at the
Hong Kong Observatory.
The
lesser impacts from typhoons in recent decades, however, is likely
tied to a lack of direct hits, the Hong Kong Observatory notes. The
number of instances of typhoon’s eye (center) moving directly over
Hong Kong – resulting in the issuance of Signal 10, the most dire
alert – has been few.
“The
tropical cyclone activity in the South China Sea was in a relatively
quiet phase during the last two decades,” the
Hong Kong Observatory writes.
“The frequency of Signal No. 10 [the eye of a storm passing over
Hong Kong] has decreased since the 1980s. The Hurricane Signal was
issued only twice in the last three decades in 1983 (Ellen)and 1999
(York).”
(Update:
The above quote is from April 2012, before the third Signal No. 10 of
the last three decades was issued for typhoon
Vicente in
July, 2012)
It
adds: “With slightly less frequent tropical cyclones affecting Hong
Kong in the last few decades, some people may wrongly think that the
typhoon risk in Hong Kong has declined.”
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