ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM Tropical Storm Harvey Discussion Number 27 NWS National Hurricane Center Miami FL AL092017 1000 PM CDT Sat Aug 26 2017 The central convection associated with Harvey has shown warming cloud tops during the past several hours, although radar data shows widespread rain continuing near and north of the center. Winds from the New Braunfels WSR-88D are near 65 kt at 1500-2500 ft near the center, but it is uncertain how well these winds are mixing down to the surface. The initial intensity is reduced to a somewhat uncertain 45 kt based mainly on the radar data. Harvey has drifted east-northeastward since the last advisory. While the model guidance is not in great agreement, it appears that the cyclone will drift southward or southeastward during the next couple of days due to the distant influence of a trough digging into the eastern United States. After that time, a building ridge over the Gulf of Mexico should cause Harvey to drift generally northward. The new forecast track is similar to the previous track and lies near the consensus models. At this time, the forecast track keeps the center of Harvey inland, as there is not enough agreement between the models that the center of Harvey will actually emerge over water. Harvey should continue to weaken to a tropical depression during the next day or so as the cyclone remains inland. As the center nears the coast, it is likely that the cyclone will maintain that status for several days as a large amount of the circulation will be over the water. By the end of the forecast period, the system should be far enough inland so that Harvey will again weaken. An alternative scenario is that Harvey could re-intensify if the center emerges over the Gulf. Key Messages: 1. While Harvey's winds are decreasing, life-threatening hazards will continue from heavy rainfall over much of southeastern Texas and from storm surge along portions of the Texas coast. 2. Catastrophic and life-threatening flooding is expected across the middle and upper Texas coast from additional rainfall of 15 to 25 inches, with isolated storm totals as high as 40 inches, through Thursday. Please heed the advice of local officials and do not drive into flooded roadways. Refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard. A summary of rainfall totals compiled by the Weather Prediction Center can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc1.html 3. A Storm Surge Warning remains in effect for portions of the Texas coast. Life-threatening storm surge flooding will be slow to recede due to the slow motion of Harvey and a prolonged period of onshore flow. For a depiction of areas at risk, see the Storm Surge Watch/Warning Graphic at hurricanes.gov. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 29.3N 97.3W 45 KT 50 MPH...INLAND 12H 27/1200Z 29.1N 97.4W 35 KT 40 MPH...INLAND 24H 28/0000Z 28.9N 97.3W 30 KT 35 MPH...INLAND 36H 28/1200Z 28.5N 97.0W 30 KT 35 MPH...INLAND 48H 29/0000Z 28.4N 96.8W 30 KT 35 MPH...INLAND 72H 30/0000Z 29.0N 96.5W 30 KT 35 MPH...INLAND 96H 31/0000Z 30.0N 96.5W 30 KT 35 MPH...INLAND 120H 01/0000Z 31.0N 96.5W 25 KT 30 MPH...INLAND $$ Forecaster Beven NNNN