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| #901744 (Received by flhurricane at: 11:03 PM 06.Sep.2017) TCDAT3 Hurricane Katia Discussion Number 6 NWS National Hurricane Center Miami FL AL132017 1000 PM CDT Wed Sep 06 2017 Satellite images indicate that Katia has a small symmetric central dense overcast with very deep convection near the center. Subjective and objective Dvorak estimates have risen since the past advisory and, after accounting for the low bias earlier, support an initial wind speed of 70 kt. With wind shear forecast to drop while the hurricane remains over very warm waters, it is puzzling to see that most of the regional hurricane guidance is only showing a small increase in wind speed. Although this area of the Gulf of Mexico is known for significant upwelling, Katia is a rather small tropical cyclone that shouldn`t stir up as much cool water from below as most hurricanes would. After considering the potential upwelling and the extremely favorable upper-level environment, the intensity forecast is raised from the previous one, but could be conservative since the SHIPS RI index is showing roughly a 50 percent of rapid intensification during the next 24 hours. Katia is drifting east-southeastward, caught in a light steering area between two ridges. The hurricane should gradually turn southwestward during the next 24 hours, then accelerate after that time due to a strengthening ridge over the northwestern Gulf of Mexico. The official forecast is very similar to the previous one, on the south side on the dynamical model consensus TVCN in the direction of the corrected consensus. Given the latest wind radii forecast, the government of Mexico has extended the hurricane watch northward to Cabo Rojo. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 21.7N 94.8W 70 KT 80 MPH 12H 07/1200Z 21.5N 94.6W 80 KT 90 MPH 24H 08/0000Z 21.3N 94.8W 90 KT 105 MPH 36H 08/1200Z 21.1N 95.4W 95 KT 110 MPH 48H 09/0000Z 20.6N 96.4W 95 KT 110 MPH 72H 10/0000Z 19.0N 98.5W 20 KT 25 MPH...POST-TROP/INLAND 96H 11/0000Z...DISSIPATED $$ Forecaster Blake |
