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Hurricane Irma Discussion Number 48
NWS National Hurricane Center Miami FL AL112017
1100 PM EDT Sun Sep 10 2017
Irma's center has moved northward across the western Florida
peninsula since it made landfall earlier this afternoon, and it is
now located over west-central Florida. NOAA WSR-88D radar data from
Tampa Bay are showing 95-100 kt winds at an elevation of about 3500
ft, so the hurricane's intensity is estimated to be 85 kt. Irma
continues to have a large wind field, and exceptional hurricane-
force wind gusts are still occurring well to the east of the center
along the Florida east coast.
Irma appears to be making some progress to the west of due north,
and the longer-term initial motion is 350/12 kt. The cyclone is
expected to swing around the eastern side of a mid-level disturbance
currently located along the U.S. Gulf Coast, which should impart a
north-northwestward to northwestward motion during the next 48
hours. Due to its recent more inland push, Irma's center is now
forecast to remain over Florida and then move over the southeastern
United States for the duration of its existence. Due to continued
land interaction and strong shear of over 30 kt, Irma should
continue to lose strength and fall below hurricane intensity
on Monday. The cyclone is then expected to become a remnant low
over western Tennessee by day 3 and dissipate by day 4.
KEY MESSAGES:
1. There is the danger of life-threatening storm surge flooding
along much of the Florida coast, including the Florida Keys, and
portions of the coasts of Georgia and South Carolina, where a Storm
Surge Warning remains in effect.
2. Irma will continue to bring life-threatening wind impacts to much
of Florida, with hurricane-force winds near the center. Also,
Irma is a large hurricane, and hurricane-force wind gusts and
sustained tropical-storm force winds extend far from the center.
Wind hazards from Irma will also spread northward through Georgia
and into portions of Alabama, Tennessee, South Carolina, and North
Carolina.
3. Irma continues to produce very heavy rain and inland flooding
across much of Florida, and these rains will spread into 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 southern
Georgia, where average rainfall totals of 8 to 15 inches and
isolated 20 inch amounts are expected. Significant river flooding is
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. The southern Appalachian Mountains will be especially
vulnerable to flash flooding. Irma is also 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 11/0300Z 27.5N 81.9W 85 KT 100 MPH...INLAND
12H 11/1200Z 29.4N 82.8W 65 KT 75 MPH...INLAND
24H 12/0000Z 31.9N 84.7W 45 KT 50 MPH...INLAND
36H 12/1200Z 33.9N 86.8W 30 KT 35 MPH...INLAND
48H 13/0000Z 35.0N 88.6W 25 KT 30 MPH...INLAND
72H 14/0000Z 37.5N 87.8W 20 KT 25 MPH...POST-TROP/INLAND
96H 15/0000Z...DISSIPATED
$$
Forecaster Berg
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