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| #873289 (Received by flhurricane at: 4:47 PM 29.Aug.2016) TCDAT2 HURRICANE GASTON DISCUSSION NUMBER 29 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 PM AST MON AUG 29 2016 Gaston's satellite presentation continues to slowly degrade, with the latest microwave data suggesting it could be undergoing an eyewall replacement. The initial wind speed is lowered to 90 kt in accordance with the latest satellite estimates. Little change in intensity is expected for the next couple of days while Gaston remains over warm waters with light-to-moderate shear, although the eyewall cycle adds a wrinkle to the forecast. In a couple of days, a gradual increase in shear, along with a decrease in SSTs, should cause a more significant weakening. Intensity guidance is a bit lower than 6 hours ago, and the latest NHC intensity forecast follows that trend. Gaston appears to be moving a bit faster, now north-northeastward at 3 kt. Due to a ridge becoming established to the southeast of the cyclone, Gaston should accelerate to the east-northeast over the next few days. The end of the forecast is tricky, with some uncertainties over how Gaston interacts with the mid-latitude westerlies and the strength of an eastern Atlantic ridge. While the overall guidance suite has shifted somewhat to the north at days 4 and 5, the ECMWF has been more consistent during the past few days and has stayed farther south. Thus, the new forecast is on the southern side of the guidance envelope, to the south of the model consensus at long range. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 31.2N 55.2W 90 KT 105 MPH 12H 30/0600Z 31.6N 54.5W 90 KT 105 MPH 24H 30/1800Z 32.2N 52.8W 85 KT 100 MPH 36H 31/0600Z 33.2N 50.7W 85 KT 100 MPH 48H 31/1800Z 34.6N 48.0W 85 KT 100 MPH 72H 01/1800Z 37.7N 39.6W 75 KT 85 MPH 96H 02/1800Z 38.5N 32.0W 55 KT 65 MPH 120H 03/1800Z 40.0N 28.0W 40 KT 45 MPH $$ Forecaster Blake |
