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Major Hurricane Irma


NJwx85

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ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM

Hurricane Irma Discussion Number  37
NWS National Hurricane Center Miami FL       AL112017
500 AM EDT Fri Sep 08 2017

Microwave images and data from an Air Force Reserve Hurricane
Hunter aircraft indicate that Irma is currently undergoing an
eyewall replacement cycle.  A recent GMI overpass showed an 50 nmi
wide outer eyewall, with the inner eyewall weakening.  The
Hurricane Hunter aircraft reported peak 700-mb winds of 147 kt in
the outer eyewall near 0500 UTC, and maximum SFMR winds were in the
125-130 kt range.  Based on these data, the initial intensity is
reduced to 135 kt.

Irma is forecast to remain in a favorable warm water, light shear
environment for the next 36-48 h.  The intensity guidance shows a
slow weakening during this time, but Irma is expected to remain at
least a Category 4 hurricane until landfall in Florida.  After
landfall, a fairly quick decay in maximum winds is expected due to
land interaction and increased shear, although Irma's large wind
field is likely to still produce hurricane-force winds over a large
area.  There are two caveats to the intensity forecast.  First, some
additional weakening could occur during the eyewall replacement,
followed by re-intensification as the cycle completes.  Second, the
ECMWF, UKMET, and NAVGEM forecast a track over or close to the
coast of Cuba that is not currently a part of the track forecast.
If this occurs, Irma could be weaker than currently forecast along
the later parts of the track.

The initial motion is west-northwestward or 285/14.  Irma should
maintain this general trajectory for the next 24-36 h as it moves
along the southwestern side of the subtropical ridge.  After that
time, the guidance is in good agreement that the ridge should break
and allow Irma to turn north-northwestward to northward.  There
remains some spread between the models on when the turn will occur,
with the GFS/Canadian being on the eastern side of the guidance and
the UKMET/NAVGEM on the left side.  The ECMWF, Florida State
Superensemble, and the HFIP Corrected consensus are in the middle
of the guidance envelope, and the new track forecast is in best
agreement with those models.  Overall, the new forecast track is
similar to the previous forecast, with minor westward adjustments
at 36 and 48 h.
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3 minutes ago, csnavywx said:

Recon pass still shows an inner eyewall max, but it is definitely weaker than the last mission. OEW steadily strengthening. Should complete sometime today, probably earlier rather than later.

Everything I'm reading is telling me the only thing that's holding it back from being 190 mph is size. Looking at angular momentum, and the friction seems to say that it could reach back to cat 5 but it'll never be 190 mph at this size. Also fascinating to read that hurricanes this large are able to deal with dry air/shear much better than their smaller counterparts even if they have higher winds. 

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Harvey's impact was rain because of it's huge fetch of tropical moisture and slow movement.  Irma's impact will be high winds + long duration.
Almost 24 hours of 'cane force winds in Miami - that has never happened before, and doesn't happen with smaller diameter storms.

The fact we get two historic hurricanes at the start of a hurricane season after a LONG dry spell is rather sobering - people forget how insane these kind of storms are after the longest Cat2+ hurricane lull in US history...

 

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Florida is going to have a problem financially. Looking at their financial statements for their wind and hail pool they only have total assets of 21 billion and when you strip out liabilities it is around 9 billion. I can't find if they have reinsurance but if they don't the state is going to have a real problem 

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3 minutes ago, Casualbrain said:

Harvey's impact was rain because of it's huge fetch of tropical moisture and slow movement.  Irma's impact will be high winds + long duration.
Almost 24 hours of 'cane force winds in Miami - that has never happened before, and doesn't happen with smaller diameter storms.

The fact we get two historic hurricanes at the start of a hurricane season after a LONG dry spell is rather sobering - people forget how insane these kind of storms are after the longest Cat2+ hurricane lull in US history...

 

Nah.  Church of Gaia indicates we're overdue for Carbon Punishment.  Nobody expected the Climate Inquisition.

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4 hours ago, 40/70 Benchmark said:

I understand that, but the point is that this particular IRC has manifested itself in this manner.

It's very difficult to get a storm back up to Cat 5 after it has been there and then weakened some.  Andrew did it, but that was reclassified after the fact.  I think David actually got to Cat 5 three times, but that's an extreme rarity.

Anyway Irma has set some amazing records, it peaked at 185 mph and stayed there for 36 hours, which is twice as long as any other hurricane in Atlantic basin recorded history (David did it for 18 hours.)  You don't expect a storm to stay at Cat 5 all the way to the coast anyway, especially when it becomes a Cat 5 so far away from the mainland.  It'll still have Cat 5 surge damage though, regardless of wind speeds.

 

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URNT12 KWBC 081002
VORTEX DATA MESSAGE  AL112017
A. 08/09:37:12Z
B. 21 deg 38 min N
  074 deg 05 min W
C. NA
D. 109 kt
E. 278 deg 18 nm
F. 022 deg 132 kt
G. 276 deg 22 nm
H. 927 mb
I. 11 C / 3076 m
J. 16 C / 3513 m
K. 16 C / NA
L. CLOSED
M. C40
N. 12345 / NA
O. 0.1 / 1 nm
P. NOAA2 2011A IRMA OB 04
MAX FL WIND 132 KT 276 / 22 NM 09:31:30Z
CNTR DROPSONDE SFC WIND 170 / 10 KTS

 

New eye is big. Going to take a while to shrink that. Unfortunately, Irma's got a while to do so.

On the upside, that inner core is big and that may give it a chance to interact with Cuba a bit if it hangs on the left side of the cone.

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3 minutes ago, No snow for you said:

Florida is going to have a problem financially. Looking at their financial statements for their wind and hail pool they only have total assets of 21 billion and when you strip out liabilities it is around 9 billion. I can't find if they have reinsurance but if they don't the state is going to have a real problem 

Feds will cover the rest.

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Barring negative interaction in some way with Cuba, I think Irma has a very good chance at strengthening over the next 24 hours or so. It's a big hurricane, so there's a limit to some extent, but I think the pressure could drop a decent amount.

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