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Tropical Storm GASTON Forecast Discussion Number 18
2016-08-27 04:52:58| National Hurricane Center (Atlantic)
Issued at 1100 PM AST FRI AUG 26 2016 000 WTNT42 KNHC 270252 TCDAT2 TROPICAL STORM GASTON DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 1100 PM AST FRI AUG 26 2016 The structure of Gaston appears to be slowly improving, with less evidence of vertical shear than earlier today. Deep convection has been forming fairly close to the center in a more symmetric fashion, but still hasn't been able to persist for very long. Subjective estimates are a little higher than earlier, but still support an initial wind speed of 55 kt for this advisory. Gaston should move into a low-shear, warm-water environment during the next 2 or 3 days, which would usually support a great deal of strengthening. However, a key hindering factor remains the nearby low-level moisture, which is forecast to substantially decrease during the next few days. This should temper the expected intensification and reduce the chances for rapid strengthening. Gaston is likely to encounter increasing upper-level flow beyond 3 days, which probably will start a weakening trend in combination with gradually cooling SSTs. Model guidance is generally in good agreement on this scenario, with less spread in the intensity models than is typically seen. The new prediction is a blend of the previous forecast and the intensity consensus. Microwave data suggest that Gaston continues to move northwestward, now at about 13 kt, a bit slower than before. The cyclone is moving between a strong upper low to the southwest and a subtropical ridge to its northeast. The ridge is forecast to gradually weaken, resulting in Gaston decelerating over the next couple of days. Steering currents get quite light in about 3 days, and the cyclone is expected to turn northeastward or east-northeastward it moves around the northwest side of a distant ridge over the eastern Atlantic. Computer models are coming into better agreement on a sharper, slower recurvature, first suggested by the ECMWF yesterday. The latest NHC forecast is close to the previous one for the first few days, then is trended eastward to follow the model trend. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 27.0N 50.8W 55 KT 65 MPH 12H 27/1200Z 28.0N 52.5W 60 KT 70 MPH 24H 28/0000Z 29.2N 54.1W 70 KT 80 MPH 36H 28/1200Z 30.2N 55.2W 80 KT 90 MPH 48H 29/0000Z 30.8N 55.7W 90 KT 105 MPH 72H 30/0000Z 31.8N 55.4W 95 KT 110 MPH 96H 31/0000Z 33.0N 52.0W 90 KT 105 MPH 120H 01/0000Z 35.0N 47.5W 80 KT 90 MPH $$ Forecaster Blake
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