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| #899760 (Received by flhurricane at: 10:56 AM 26.Aug.2017) TCDAT4 Hurricane Harvey Discussion Number 25 NWS National Hurricane Center Miami FL AL092017 1000 AM CDT Sat Aug 26 2017 Harvey has been inland for about 12 hours and weakening is under way. Doppler radar data indicate that winds have decreased to 65 kt, and that is the intensity used in this advisory. Since Harvey is over land, a continued weakening is anticipated, and the NHC forecast uses the trend provided by the SHIPS decay model. However, if a portion of Harvey's circulation remains over the Gulf of Mexico, the cyclone could weaken at a slower rate than shown here. The hurricane is moving very slowly toward the north at about 2 kt. Harvey is embedded within very light steering currents, and global models keep this weak flow in place for the next several days. Based on this pattern, Harvey could easily meander for the next 4 to 5 days over southeast Texas as indicated in the NHC forecast. The only agreement among the track guidance is that Harvey is certainly not going anywhere fast. This slow motion of the cyclone is expected to exacerbate the potential for catastrophic flooding from heavy rainfall at least through the middle of next week. Please note that hourly Tropical Cyclone Updates (TCUs) have been discontinued due to the degradation of Harvey's center on radar. Key Messages: 1. While Harvey's winds have begun to weaken, 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 heavy rainfall of 15 to 30 inches, with isolated amounts 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. 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 26/1500Z 28.9N 97.3W 65 KT 75 MPH...INLAND 12H 27/0000Z 29.1N 97.4W 45 KT 50 MPH...INLAND 24H 27/1200Z 29.2N 97.5W 40 KT 45 MPH...INLAND 36H 28/0000Z 29.0N 97.5W 35 KT 40 MPH...INLAND 48H 28/1200Z 28.7N 97.0W 30 KT 35 MPH...INLAND 72H 29/1200Z 28.7N 96.7W 30 KT 35 MPH...INLAND 96H 30/1200Z 29.5N 96.7W 30 KT 35 MPH...INLAND 120H 31/1200Z 30.5N 96.5W 30 KT 35 MPH...INLAND $$ Forecaster Avila/Lapenta |
