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Hurricane Irma Discussion Number 39
NWS National Hurricane Center Miami FL AL112017
500 PM EDT Fri Sep 08 2017
Latest data from an Air Force Hurricane Hunter plane a few hours ago
indicate that Irma's intensity continues to fluctuate, and the
winds are estimated at 135 kt. The last minimum central pressure
was 925 mb. Another reconnaissance plane will check Irma soon.
The environment is favorable for Irma to maintain its category 4
status, and only unpredictable eyewall replacement cycles could
result in intensity fluctuations during the next 48 hours. The
interaction of the hurricane's circulation with Cuba will probably
not result in any relevant change in intensity. In summary, the NHC
forecast brings Irma near south Florida as a category 4 hurricane.
After landfall, interaction with land and an increase in wind shear
should induce gradual weakening.
Satellite images and radar fixes from Cuba indicate that Irma has
slowed down and is now moving toward the west or 280 degrees at
about 10 kt. The hurricane should continue on this track for the
next 12 hours to 24 hours, and this track will bring the core of
Irma very close to the north coast of Cuba. After that time, Irma
should reach the southwestern edge of the subtropical high and begin
to move toward the northwest and north-northwest toward the Florida
peninsula. The precise moment of this turn is still uncertain, and
that is why NHC emphasizes that nobody should focus on the exact
track of the center. This afternoon's NHC forecast was again
adjusted a little bit westward following the trend of the ECMWF
model and both the HFIP corrected consensus and the FSU
Superensemble. In fact, these 3 aids continued to be tightly packed.
1. Irma will continue to bring life-threatening wind, storm surge,
and rainfall hazards to portions of the Bahamas and the north coast
of Cuba, especially over the adjacent Cuban Keys, through Saturday.
2. Irma is expected to make landfall in Florida as an extremely
dangerous major hurricane, and will bring life-threatening wind
impacts to much of the state regardless of the exact track of the
3. There is the danger of life-threatening storm surge inundation in
southern Florida and the Florida Keys during the next 36 hours,
where a Storm Surge Warning is in effect. The threat of significant
storm surge flooding along the southwest coast of Florida has
increased, and 8 to 12 feet of inundation above ground level is
possible in this area. This is a life-threatening situation.
Everyone in these areas should take all actions to protect life and
property from rising water and follow evacuation instructions from
4. Irma is expected to produce very heavy rain and inland flooding.
Total rain accumulations of 8 to 15 inches, with isolated amounts of
20 inches are expected over the Florida Keys and much of the Florida
peninsula through Tuesday night. The highest amounts are expected
over the eastern Florida peninsula and upper Florida Keys. Irma
will likely bring periods of heavy rain to much of Georgia, South
Carolina, and western North Carolina early next week, including some
mountainous areas which are more prone to flash flooding. All areas
seeing heavy rainfall from Irma will experience a risk of flooding
and flash flooding.
FORECAST POSITIONS AND MAX WINDS
INIT 08/2100Z 22.1N 76.5W 135 KT 155 MPH
12H 09/0600Z 22.4N 78.2W 135 KT 155 MPH
24H 09/1800Z 23.0N 79.9W 135 KT 155 MPH
36H 10/0600Z 24.1N 81.0W 140 KT 160 MPH
48H 10/1800Z 25.7N 81.5W 125 KT 145 MPH
72H 11/1800Z 30.6N 83.0W 50 KT 60 MPH...INLAND
96H 12/1800Z 35.0N 85.9W 25 KT 30 MPH...INLAND
120H 13/1800Z 35.6N 87.0W 20 KT 25 MPH...POST-TROP/INLAND