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Models Show Irma Tracking Toward 88 Degree (F) Waters Before Setting Sights on Florida, Georgia and South Carolina
6
September, 2017
As
of yesterday and today, Irma
was the strongest storm ever to form in the Central Atlantic.
Fueled by record atmospheric and ocean heat and related high
atmospheric moisture content, the storm plowed into the Leeward
Islands of Barbuda, St. Martin and Anguilla as a top-strength
Category 5 monster hurricane.
(Alex
Woolfall takes shelter in a concrete stairwell in St. Martin to avoid
Irma’s catastrophic winds. It’s worth noting that hurricanes are
heat engines. Tapping 87 C sea surface temperatures and producing 100
percent humidity would result in the very hot conditions Alex was
experiencing 7 hours ago. We’re all pulling for Alex and those like
him who were trapped in the belly of this massive beast. His last
report was at 5:45 AM.)
Still thunderous sonic boom noises outside & boiling in stairwell. Can feel scream of things being hurled against building. #HurricaineIrma
As
Irma’s eyewall began to pass over Barbuda, a
reporting station recorded a wind gust of 155 mph before it was
knocked out.
That island of 1,800 people is now completely cut off from the
outside world. Having just experienced winds in excess of those
hosted by Andrew and Camille, it is likely that catastrophic damage
was inflicted.
On
St. Martin, which also passed through Irma’s eye and most intense
wind bands, initial reports are also showing very considerable
damage. Four
of the strongest buildings on the island have been destroyed.
And it is expected that most structures across this French/Dutch
shared island which is home to 75,000 have seen moderate to
catastrophic damage.
#Irma is wrecking Saint Martin...
Puerto Rico is next and Florida still to come.
#njmorningshow @B911Nature
Keraunos
(Footage
this morning, apparently taken from a camera near the airport at
Simpson Bay in St. Martin shows debris, flooding, and very strong
winds.)
Anguilla,
which is north of St. Martin and is home to another 15,000 souls,
passed through the northern eye wall. This is typically the most
intense part of a hurricane. So far, reports from Anguila are spotty.
But the damage there is likewise expected to be catastrophic.
As
of the 5 PM advisory,
according to the National Hurricane Center, Irma is still a
devastatingly powerful Category 5 monster hurricane hosting maximum
sustained winds of 185 mph. The storm had seen some weakening due to
apparent eyewall replacement and mild wind sheer — which pushed
pressures back up to 920 mb from a low of 914 mb last night earlier
today. However, this weakening was not significant enough to impact
Irma’s amazing wind intensity. Since that time, Irma’s central
dense overcast has thickened while pressures have dropped back down
to 914 mb as of the 5 PM advisory.
(Irma
tracking just slightly north of the officially projected path from
the NHC as of early afternoon on Wednesday. Image source: The
National Hurricane Center.)
As
the storm passes toward the Virgin Islands, roars by Puerto Rico, and
howls into the Turks, Caicos and Bahamas, it
is likely that some weakening will occur.
Despite this fact, the storm is expected to maintain Category 5
intensity through at least the next 48 hours. After 72 hours, the
official forecast calls for Irma to drop to strong Category 4
intensity and eventually a strong Category 3 by Monday. However, some
models like the GFS show Irma again strengthening as it taps very
warm waters off Florida.
(Very
hot sea surface temperatures off Florida could provide fuel that
allows Irma to strengthen a second time as predicted in forecast
models like the GFS. Image source: Earth
Nullschool.)
Most
models are now starting to settle on a consensus that brings Irma
toward Florida and along a course that may threaten Georgia and South
Carolina. The GFS model shows Irma tapping extremely hot sea surface
temperatures in the range of 88 degrees Fahrenheit (about 3.5 F
hotter than average) and pumping up again into very strong Category 5
intensity with an 895 mb minimum central pressure off Florida by
Sunday. This would be a stronger intensity than the 914 mb reached
last night by measure of pressure alone.
(The
GFS, ECMWF and other major models are starting to agree on a
consensus track which has Irma raking the Florida coast before
threatening Georgia and the Carolinas. Image source: The
National Hurricane Center.)
GFS
shows the storm raking most of the Florida coast as it bounces from
one landfall or near landfall to another across the eastern seaboard
before making a final landfall as a 924 mb monster along the
Georgia-South Carolina border. Meanwhile, another major model — the
Euro (ECMWF) — has the storm following approximately the same path
at a lower intensity.
Though
the GFS modeled intensity does not jibe with the
official forecast —
which calls for weakening of Irma to strong Cat 4 and then strong Cat
3 status — we should not completely rule out the GFS prediction due
to those very warm ocean surfaces mentioned above. If predicted wind
shear does not emerge, then it would allow Irma to more effectively
tap those very warm waters off Florida and hit a second peak
intensity. And if such a forecast were realized, it would produce a
seriously catastrophic disaster for the U.S. East Coast.
(Models
are starting to come into consensus on Irma’s track — which is
zeroing in on it raking the Florida coast and then slamming into
Georgia or South Carolina — but forecast intensity varies widely.
GFS shows Irma off Florida at an intensity stronger than her present
extreme strength by Sunday. Image source: Tropical
Tidbits.)
Of
course, the official forecast track and intensity — in which a
strong Category 4 storm rakes coastal Florida and then tracks up into
Georgia or South Carolina to make final landfall as a strong Cat 3 is
bad enough. So in this case, we are looking a present forecast
scenarios in which models are starting to come into consensus on
track that range from bad (official Cat 4 and then Cat 3 intensity
storm impacting Florida, Georgia and the Carolinas) to worse (GFS
potential for a very strong cat 5 storm threatening the U.S.
Southeast Coast).
(UPDATED
— UPDATES TO FOLLOW)
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