| Track: http://www.nhc.noaa.gov/refresh/graphics_at2+shtml/085705.shtml?5day#contents Floater: http://www.ssd.noaa.gov/PS/TROP/floaters/07L/07L_floater.html HURRICANE GASTON DISCUSSION NUMBER 39 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 AM AST THU SEP 01 2016 Gaston has weakened a little overnight. The cloud pattern has lost some organization with the convection more asymmetric and not quite as deep as it was several hours ago. The Dvorak CI-numbers have decreased to 4.5/77 kt from both TAFB and SAB, and the initial wind speed is lowered to 80 kt based on that data. Gaston is expected to cross the 26 deg C isotherm later today while it remains in an environment of moderate southwesterly shear. These conditions should cause steady weakening, and Gaston will likely fall below hurricane strength by tonight. Continued weakening is forecast when the cyclone moves near the Azores on Friday. The NHC intensity forecast is in best agreement with the intensity model consensus. The hurricane is moving quickly east-northeastward about 17 kt. This general motion is expected to continue during the next day while Gaston remains embedded in the mid-latitude westerlies. A decrease in forward speed is predicted after that time due to the approach of a large extratropical low. Gaston will likely be absorbed by the extratropical low in about 3 days. The NHC track forecast lies near the middle of the tightly-packed models. Based on the current forecast, the Azores Meteorological Service has issued a Tropical Storm Warning for the western-most islands of Flores and Corvo. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 36.8N 43.3W 80 KT 90 MPH 12H 01/1800Z 37.9N 39.9W 70 KT 80 MPH 24H 02/0600Z 38.7N 35.4W 60 KT 70 MPH 36H 02/1800Z 39.2N 31.8W 50 KT 60 MPH 48H 03/0600Z 40.0N 29.0W 40 KT 45 MPH 72H 04/0600Z...DISSIPATED $$ Forecaster Cangialosi HURRICANE GASTON ADVISORY NUMBER 39 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 AM AST THU SEP 01 2016 ...GASTON WEAKENS A LITTLE...TROPICAL STORM WARNING ISSUED FOR THE WESTERN AZORES... SUMMARY OF 500 AM AST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...36.8N 43.3W ABOUT 805 MI...1300 KM W OF FAIAL ISLAND IN THE CENTRAL AZORES ABOUT 895 MI...1440 KM W OF LAJES AIR BASE IN THE AZORES MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H PRESENT MOVEMENT...ENE OR 60 DEGREES AT 20 MPH...31 KM/H MINIMUM CENTRAL PRESSURE...977 MB...28.85 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Azores Meteorological Service has issued a Tropical Storm Warning for Flores and Corvo in the western Azores. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Flores and Corvo in the western Azores A Tropical Storm Watch is in effect for... * Faial, Pico, Graciosa, Sao Jorge, and Terceira in the central Azores A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 500 AM AST (0900 UTC), the center of Hurricane Gaston was located near latitude 36.8 North, longitude 43.3 West. Gaston is moving toward the east-northeast near 20 mph (31 km/h), and this general motion is expected to continue during the next day or two. On the forecast track, the center of Gaston will move near the western Azores on Friday and the central Azores by Friday night. Maximum sustained winds have decreased to near 90 mph (150 km/h) with higher gusts. Weakening is forecast during the next 48 hours, and Gaston is expected to lose hurricane intensity by early Friday before it reaches the western Azores. Hurricane-force winds extend outward up to 45 miles (75 km) from the center and tropical-storm-force winds extend outward up to 175 miles (280 km). The estimated minimum central pressure is 977 mb (28.85 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected in the western Azores on Friday. Tropical storm conditions are possible in the central Azores late Friday and Friday night. NEXT ADVISORY ------------- Next intermediate advisory at 800 AM AST. Next complete advisory at 1100 AM AST. $$ Forecaster Cangialosi |