Record Hot Atlantic Basin to Fuel Brutish 2016 Hurricanes?
20
July, 2016
Last
week, Gulf of Mexico sea surface temperatures off Tampa Bay were
outrageously hot. On July 10, the ocean temperature measure hit 93
degrees Fahrenheit (34 Celsius). By the 11th, temperatures had warmed
still more. And by the 12th, ocean surfaces had hit a sweltering 95 F
(35 C).
It’s
rare that you ever see ocean waters anywhere on Earth become so hot.
And when you do, it’s often in places like the Red Sea or the
Persian Gulf — not the Gulf of Mexico. But in the new world driven
to increasingly extreme warmth by human fossil fuel emissions, the
potential heat bleeding off of ocean surfaces has jumped by quite a
bit.
And
it’s not just true with Tampa Bay. According
to Michael Lowry,
a hurricane specialist at The Weather Channel, the whole of the Gulf
of Mexico recorded its hottest average daily July sea surface
temperature at 86.3 F (30.1 C).
Atlantic
Basin Sees Record July Heat
The
record ocean heat extends still further. National
Hurricane Center storm
specialist Eric
Blake earlier
today noted that the entire Atlantic Basin west of longitude 60° W
is the hottest it’s ever been during any hurricane season,
including the record storm year that was 2005. In other words, a huge
zone of ocean stretching from the far eastern edge of the Caribbean,
encompassing all of the Gulf of Mexico and running up the entire
eastern seaboard of the US and on to just east of Bermuda is now
seeing the hottest July ocean temperatures ever experienced in our
modern records.
(Sea
surface temperatures hit record ranges for the western North Atlantic
during recent days. CDAS image via Eric
Blake.)
Overall
ocean surface temperatures range from 0.5 to 1 C above average for
the Caribbean, 0.5 to 2.5 C above average for the Gulf of Mexico and
1 to 6 C above average for the coastal US Atlantic. These
temperatures compare to an already hotter-than-normal 1981-to-2010
average, so departures from the 20th-century average would be even
greater.
Record
Ocean Heat to Strengthen 2016 Atlantic Hurricanes?
Hot
ocean temperatures are fuel for the powerful storms we call
hurricanes. But it’s not the only ingredient. Low-pressure
formation at the surface, a lift in the atmosphere, high pressure
aloft, widely available moisture, and a lack of wind shear are all
atmospheric assists that aid in storm formation. So far during July,
a dearth of these other factors has resulted in no storms as of yet
for the month.
2016,
however, has already seen four named tropical storms —
including the odd winter Hurricane Alex and three tropical storms
which spun up during June. And given the extreme ocean surface heat
in the Northwestern Atlantic, some agencies are beginning to call for
the potential for more and possibly powerful storms on the way.
The main driving elements for hurricane formation in the Atlantic are the SST values present in the Atlantic itself, the predicted wind shear conditions in the region, and the SST pattern found in the Pacific related to the timing of the transition from El Niño to La Niña in the equatorial Pacific Ocean. Model predictions anticipate that the second part of this 2016 season will be more active as La Niña intensifies in the Pacific and becomes one of the main drivers of activity for the Atlantic.
As
a result of the combined extreme Atlantic Basin heat and the
predicted emergence of La Niña conditions in the equatorial
Pacific, some
hurricane monitors are upping the number of storms predicted for
2016.
Colorado State is now forecasting 15 named storms as opposed to its
earlier 13. However, its prediction for the number of major
hurricanes has remained the same at two, with one affecting the US.
(Models
predict what appears to be a very healthy tropical wave emerging off
the west coast of Africa by July 28. If a tropical cyclone results
that tracks into record warm western Atlantic waters, peak storm
intensity near the US could be quite extreme. Hat tip tometeorologist
Ryan Maue for
the ECMWF infrared
forecast capture.)
However,
predicted warm-water formation in the Pacific off Mexico could dampen
Atlantic storms by pushing in more dry air and developing a higher
degree of wind shear than is typical during a La Niña year. In
addition, large African dust flows currently over the tropical
Atlantic also may tend to suppress storm formation.
Given
the ambiguous conditions noted above, the situation still appears to
be a bit of a crapshoot. That said, those extreme sea surface
temperatures near the US will likely continue to ramp up through
August. And that’s a situation that creates a potential where
storms approaching the US rapidly intensify as they hit those
record-hot waters. Overall, it’s a pretty dicey environment for
forecasters and one that has been wagged in no small amount by
conditions related to human-forced warming.
Links/Attribution/Statements
Hat
tip to DT Lange
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