https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/10/22/extremely-dangerous-category-4-hurricane-patricia-to-slam-west-coast-of-mexico-friday/
[videos and images in on-line article]
‘Potentially catastrophic’ Patricia becomes strongest hurricane ever
recorded, to slam Mexico today
By Jason Samenow October 23 at 11:05 AM
Early Friday, monstrous Hurricane Patricia became the strongest
hurricane ever measured by the National Hurricane Center. Patricia is
forecast to make landfall on Mexico’s west central coast Friday night
with destructive winds, torrents of rain, and a devastating storm surge.
The Category 5 storm’s maximum sustained winds have strengthened to an
astonishing 200 mph. “This makes Patricia the strongest hurricane on
record in the National Hurricane Center’s area of responsibility (AOR)
which includes the Atlantic and the eastern North Pacific basins,” NHC
said. “The minimum central pressure estimated from the aircraft data,
880 mb, is the lowest ever for our AOR.”
Small fluctuations in intensity are possible before the storm comes
ashore. As of its 11 a.m. update Friday, the NHC predicts Patricia will
maintain peak winds of 200 mph when it strikes land, which would likely
be the strongest ever estimated or recorded at landfall, anywhere in the
world, including Super Typhoon Haiyan, which struck the Philippines with
peak winds estimated at 195 mph in 2013.
Over the 30 hours spanning late Wednesday night and early Friday
morning, Patricia’s peak winds increased by 140 mph, morphing from a
loosely organized conglomeration of thunderstorms to the planet’s
strongest and most wicked class of storm.
The rate of the storm’s intensification is nothing short of historic.
“Patricia is estimated to have intensified 85 kt [100 mph] in the past
24 hours,” the National Hurricane Center said in its 11 p.m. update
Thursday. “This is a remarkable feat, with only Linda of 1997
intensifying at this rate in the satellite era.”
Centered 125 miles offshore the west coast of central of Mexico, as of
11 a.m. (ET) Friday, Patricia threatens to come ashore somewhere between
San Blas and Punta San Telmo, where a hurricane warning is in effect.
This zone includes the resort town of Puerto Vallarta, with a population
of just over 200,000 people.
If the storm follows the middle of the forecast track, its most intense
core would miss Puerto Vallarta as well as Manzanillo, the other major
population center (roughly 110,000 people) in the warning zone. However,
these areas would still likely be lashed by strong winds and intense
rainfall.
Patricia’s most intense Category 5 winds extend just five to 10 miles
from the center, which will limit the real estate subject to potential
destruction.
But in that small zone subject to the storm’s violent inner core, the
impacts will be devastating – not unlike a strong tornado shredding the
same area for an extended duration.
The storm has been able to achieve its historic intensity by developing
over some of the warmest ocean temperatures in the Northern Hemisphere,
over 86 degrees.
Tropical storms conditions are beginning in the hurricane warning area
and the worst conditions are expected Friday afternoon and evening, when
destructive winds are likely. Patricia is also forecast to produce 6-12
inches of rainfall, with isolated amounts to 20 inches, particularly in
higher terrain.
“In addition to the coastal impacts, very heavy rainfall is likely to
cause life-threatening flash floods and mud slides in the Mexican states
of Jalisco, Colima, Michoacan and Guerrero …. into Saturday,” the NHC
warned.
The NHC says a ‘catastrophic’ storm surge, or rise in coastal waters, is
possible just to the right or south of where the storm makes landfall.
The surge would inundate low lying areas at the shore with impacts
accentuated by ‘large and destructive’ waves.
After the storm comes ashore, it is expected to rapidly weaken. However,
it will produce substantial rain throughout central Mexico’s interior
and is forecast to feed into a serious rainfall event in central and
eastern Texas.
It is the 22nd category 4 or 5 storm to form in the Northern Hemisphere
this year, which is also the greatest number ever recorded.
====================================================================
http://www.washingtonpost.com/news/energy-environment/wp/2015/10/23/why-hurricanes-like-patricia-are-expected-on-a-warmer-planet/
[links and images in on-line article]
Why record-breaking hurricanes like Patricia are expected on a warmer planet
By Chris Mooney October 23 at 10:56 AM
First there was Supertyphoon Haiyan — which peaked out at 170-knot or
196 mile-per-hour winds in 2013 as it slammed the Philippines. And now
there is Patricia, forecast to soon hit Mexico, with currently estimated
maximum sustained wind speeds of 175 knots or, that’s right, over 200
miles per hour.
It is officially the strongest hurricane ever measured by the U.S.
National Hurricane Center, based on both its wind speed (175 knots) and
its minimum central pressure (880 millibars). The wind measurement
“makes Patricia the strongest hurricane on record in the National
Hurricane Center’s area of responsibility (AOR) which includes the
Atlantic and the eastern North Pacific basins,” the center said this
morning.
And in this case the measurement has added weight because it is based on
data collected from an aircraft, rather than mere satellite imagery. “We
would like to acknowledge deeply the Air Force Hurricane Hunters for
their observations establishing Patricia as a record-breaking hurricane.
Clearly, without their data, we would never have known just how strong
a tropical cyclone it was,” wrote National Hurricane Center forecaster
Richard Pasch this morning.
So how could this happen? The first reason is the presence of an El Nino
year which generally leads to hyperactive hurricane activity in the
Eastern Pacific basin, says Kerry Emanuel, an MIT hurricane expert, by
e-mail. Emanuel has derived a way of measuring the maximum potential
intensity that a hurricane can achieve, in light of the climatic
conditions in which it forms, which include the sea temperature and also
the temperature high in the atmosphere above the storm.
“Potential intensity was particularly high in the region where Patricia
developed,” Emanuel says. He provided this figure to underscore the point:
So what does this say about climate change?
Certainly, record-breaking hurricanes raise questions about longstanding
predictions that global warming, by raising ocean temperatures, should
also strengthen these storms. The issue, however, is beset by
data-related difficulties, since storm measurement techniques are
continually improving (creating a kind of apples-and-oranges problem
when comparing past strong storms with present ones) and are also highly
variable around the world — thus, hurricane hunter flights are far more
common in the Atlantic than in the Northeast Pacific, where Patricia formed.
Still, there have been widespread predictions that hurricanes should
become stronger, on average, in a warmer world. Summarizing the current
research, the Geophysical Fluid Dynamics Laboratory of the National
Oceanic and Atmospheric Administration puts it this way: “Anthropogenic
warming by the end of the 21st century will likely cause tropical
cyclones globally to be more intense on average….This change would imply
an even larger percentage increase in the destructive potential per
storm, assuming no reduction in storm size.”
But of course, it’s not the end of the 21st century — it’s 2015. So are
we seeing the change already, with Haiyan and now Patricia?
“The fact that we have broken records now in the eastern and western
Pacific is curious, but we are still dealing with the statistics of
small numbers so inferences are dangerous,” Emanuel says by e-mail.
Emanuel also cautions that because most Eastern Pacific storms are not
measured by aircraft, there could have been a stronger one in the past
that was not detected. Nonetheless, he recently published research
suggesting the theoretical possibility of hyper-strong hurricanes in
certain regions as global warming continues.
While one storm is only one storm and can never substitute for a
comprehensive statistical analysis, the fact remains that the link
between warm seas and strong storms — the theoretical reason for
believing hurricanes will worsen due to climate change — is starkly
apparent in this case.
“The [sea surface temperatures] are so high over such huge areas, that
the moisture flowing into the storm, that provides it primary fuel, must
be higher than it has ever been before,” says Kevin Trenberth, a climate
researcher at the National Center for Atmospheric Research, by e-mail.
“It still requires the right set up to convert that into an intense
storm but the environment is surely ripe. That consists, of course, of a
substantial El Nino-related component but also the background global
warming that has a memory through the ocean heat content.”
Trenberth points out that ocean surface temperatures in the region are
warmer than 30 degrees Celsius, or 86 degrees Fahrenheit, “the warmest
anywhere around.” “The subsurface ocean is exceptionally warm as well,”
he adds.
“As ocean temperatures continue to warm as a result of human-caused
climate change, we expect hurricanes to intensify, and we expect to
cross new thresholds. Hurricane Patricia and her unprecedented 200
mile-per-hour sustained winds, appears to be one of them now,
unfortunately,” adds Michael Mann, a climate researcher at Penn State
University.
The global prediction of more intense hurricanes is one thing, but what
about a regional prediction? After all, hurricanes (and typhoons) form
in different regions or “basins” of the world, and these might be
differentially affected in a world that is warming.
A recent study in the Journal of Climate by NOAA’s Thomas Knutson and
colleagues actually did find that the northeast Pacific, where Patricia
formed, is an area where storms are expected to intensify. “We project
for the NE Pacific basin as a whole about 8 percent increase in
hurricane wind intensities by the late 21st century and almost a 500%
increase in Cat 4-5 days,” said Knutson by email.
The key — and difficult — question is whether or not this change is
already manifesting itself. Theoretically it should be, but it’s also
not clear in the data, says Knutson:
I would speculate that this signal, if it were to happen in the
real world, is likely already underway at least to some extent based on
the anthropogenic warming we’ve already had to date. But, importantly,
there does not seem to be a detectable signal of this type in the real
world to date, at least based on storm lifetime maximum intensity data
since 1982.
So in sum, scientists will never attribute one single event to climate
change or say that it was caused by a warming planet; and with this
event as with all weather events there are multiple causes, most
prominently El Nino.
Nonetheless, we can say this: Record-setting hurricanes like Patricia
are consistent with one major prediction that climate researchers have
made for some time about the consequences of a warming world.
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