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Tropical Depression Irma Discussion Number 52

Tropical Depression Irma Discussion Number 52 NWS National Hurricane Center Miami FL AL112017 1100 PM EDT Mon Sep 11 2017 Irma continues to move farther inland and is approaching the Georgia-Alabama border, with a large rain shield spread across much of the southeastern United States. There have been no surface reports of sustained tropical-storm-force winds from within the tropical storm warning areas, so it is assumed that Irma has weakened to a tropical depression with maximum winds of 30 kt. Winds should continue to decrease over the next day or so while Irma remains over land and is hammered by 40 kt of shear. These conditions should also cause the deep convection to die off, and Irma is likely to become a remnant low in about 24 hours. The global models are then in agreement that the remnant low will dissipate by 48 hours. Irma has turned northwestward with an initial motion of 325/14 kt. The depression is embedded within a larger cyclonic gyre, which is expected to move northwestward through Monday, and then turn north-northwestward over western Tennessee or western Kentucky before it dissipates. Water levels have fallen below the storm surge warning criteria along the southeastern United States coast and the Florida west coast. The Storm Surge Warnings in those areas have therefore been discontinued. Future information on this system can be found in Public Advisories issued by the Weather Prediction Center beginning at 5 AM EDT, under AWIPS header TCPAT1, WMO header WTNT31 KWNH, and on the web at http://www.wpc.ncep.noaa.gov. KEY MESSAGES: 1. Irma continues to produce very heavy rain across the southeastern United States. Intense rainfall rates are leading to flash flooding and rapid rises on creeks, streams, and rivers. Significant river flooding will persist over the Florida peninsula in the wake of Irma and across Georgia, South Carolina and north-central Alabama where additional heavy rains are expected. Portions of these states within the southern Appalachians will be especially vulnerable to flash flooding. Irma is also expected to produce heavy rains in northern Mississippi and southern portions of Tennessee and North Carolina, where local flooding may occur. 2. Storm surge flooding is subsiding along portions of the coasts of western Florida, Georgia, and South Carolina. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 32.4N 84.9W 30 KT 35 MPH...INLAND 12H 12/1200Z 33.8N 86.4W 25 KT 30 MPH...INLAND 24H 13/0000Z 35.2N 88.2W 25 KT 30 MPH...POST-TROP/INLAND 36H 13/1200Z 36.4N 88.6W 20 KT 25 MPH...POST-TROP/INLAND 48H 14/0000Z...DISSIPATED