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| #872980 (Received by flhurricane at: 10:47 PM 25.Aug.2016) TCDAT2 TROPICAL STORM GASTON DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 1100 PM AST THU AUG 25 2016 Gaston continues to have an asymmetric satellite appearance due to strong southwesterly shear. Still, the cyclone is producing persistent deep convection near the center, and Dvorak estimates suggest the initial wind speed remains near 55 kt. The shear should decrease tomorrow due to Gaston moving into a favorable position to the north of an upper-level low. In addition, the water temperatures are forecast to be warming up during the next few days, which should also promote strengthening. Due to recent microwave data showing that the inner core has been disrupted, only a slow intensification is shown in this forecast. In the longer term, models are not in great agreement on the upper-level wind pattern, and I have elected to level off the intensification. The new NHC prediction is a blend of the previous one and the model consensus. It should be noted that, while not explicitly shown below, a majority of the guidance show Gaston becoming a major hurricane at some time in the day 3 to 5 period. The initial motion remains northwestward at 15 kt. Gaston should move northwestward during the next day or so around a mid-level ridge over the east-central Atlantic. In about 36 hours, the ridge is forecast to build to the north of Gaston, which will likely cause the cyclone to turn west-northwestward. Early next week, Gaston should turn northward as the ridge weakens, then recurve into the mid-latitude westerlies in 4 days or so. Model guidance, however, is not in good agreement on the exact details, with timing and speed differences in both the tropical cyclone's position and the potential mid-latitude shortwave that causes recurvature. Since there have been no substantive changes to the model guidance in this cycle, the new NHC prediction is basically just an update of the previous one. It is fair to say that the end of this forecast is of pretty low confidence. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 22.8N 46.4W 55 KT 65 MPH 12H 26/1200Z 24.5N 48.1W 55 KT 65 MPH 24H 27/0000Z 26.2N 50.7W 60 KT 70 MPH 36H 27/1200Z 27.5N 53.1W 65 KT 75 MPH 48H 28/0000Z 28.6N 54.9W 75 KT 85 MPH 72H 29/0000Z 30.5N 57.0W 90 KT 105 MPH 96H 30/0000Z 32.5N 57.0W 95 KT 110 MPH 120H 31/0000Z 34.5N 53.0W 95 KT 110 MPH $$ Forecaster Blake |
