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Hurricane Irma Discussion Number  47
NWS National Hurricane Center Miami FL       AL112017
500 PM EDT Sun Sep 10 2017

Irma made landfall a couple of hours ago near Marco Island,
Florida with an estimated intensity of 100 kt.  The eye just
passed over Naples, and assuming some decay over land, the current
intensity estimate is 95 kt.  The interaction with the Florida
Peninsula along with strong southwesterly shear should cause
significant weakening, but Irma's large and powerful circulation
will likely maintain hurricane strength until Monday morning at the
earliest.  Irma should be well inland and weaken to a remnant low in
72 hours.  The official intensity forecast is above the model
consensus.

Center fixes indicate a slightly west of due northward motion at
about 350/12 kt.  Global models indicate that Irma is embedded
within a broader cyclonic mid-level gyre.  The cyclone is expected
to be steered around the eastern side of this gyre over the next few
days.  This will take the system inland over the southeastern
United states within a day or so.  The track guidance remains in
good agreement, and the official forecast is close to the model
consensus with a slight lean toward the ECMWF solution.  This is
very close to the previous NHC track.

KEY MESSAGES:

1. Life-threatening wind and storm surge from Irma will continue in
the Florida Keys and southwestern Florida and spread into central
and northwestern Florida tonight and Monday.

2. There is imminent danger of life-threatening storm surge flooding
along much of the Florida west coast, including the Florida Keys,
where a Storm Surge Warning is in effect.  The threat of
catastrophic storm surge flooding is highest along the southwest
coast of Florida, where 10 to 15 feet of inundation above ground
level is expected.  This is a life-threatening situation.

3. Irma will bring life-threatening wind impacts to much of Florida
regardless of the exact track of the center.  Wind hazards from Irma
are also expected to spread northward through Georgia and into
portions of Alabama, Tennessee, South Carolina, and North Carolina.

4. Irma is producing very heavy rain and inland flooding across much
of Florida, which will quickly spread to the rest of the southeast
United States.  Intense rainfall rates of 2 to 4 inches per hour is
leading to flash flooding and rapid rises on creeks, streams, and
rivers.  Significant river flooding is likely over the next five
days in the Florida peninsula and southeast Georgia, where average
rainfall of 8 to 15 inches and isolated 20 inch amounts are
expected.  Significant river flooding is also possible beginning
Monday and Tuesday in much of eastern and central Georgia, western
South Carolina, and western North Carolina, where average rainfall
of 3 to 8 inches and isolated 12 inch amounts are expected.
Mountainous parts of these states will be especially vulnerable to
flash flooding.  Farther west, Irma is expected to produce average
amounts of 2 to 5 inches in parts of Mississippi, Alabama and
Tennessee, where isolated higher amounts and local flooding may
occur.

FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 26.2N  81.8W   95 KT 110 MPH...INLAND
 12H  11/0600Z 28.0N  82.5W   75 KT  85 MPH...INLAND
 24H  11/1800Z 30.7N  83.9W   55 KT  65 MPH...INLAND
 36H  12/0600Z 33.1N  86.0W   35 KT  40 MPH...INLAND
 48H  12/1800Z 34.5N  88.3W   30 KT  35 MPH...INLAND
 72H  13/1800Z 36.5N  89.0W   25 KT  30 MPH...POST-TROP/INLAND
 96H  14/1800Z 39.0N  86.5W   20 KT  25 MPH...POST-TROP/INLAND
120H  15/1800Z...DISSIPATED

$$
Forecaster Pasch

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