000 WTNT43 KNHC 130900 TCDAT3 TROPICAL STORM GONZALO DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 500 AM AST MON OCT 13 2014 The satellite presentation of Gonzalo has gradually improved overnight with increased banding features seen in both infrared satellite images and Guadeloupe radar. The small inner core has also become a little better defined in the radar imagery. Dvorak data T-numbers from SAB and TAFB are 3.0 and 3.5, respectively, and the initial wind speed has been increased to 50 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the cyclone in a few hours, which should provide a better assessment of Gonzalo's intensity and size. Although some mid-level dry air is noted to the west of the cyclone, low shear and warm water should favor strengthening during the next several days. The NHC intensity forecast calls for steady intensification and Gonzalo is forecast to become a hurricane in 24 to 36 hours. The updated intensity forecast is close to the SHIPS model and is very similar to the previous advisory. The initial motion estimate is 280/9 kt. Gonzalo is forecast to turn west-northwestward, then northwestward during the next day or so, while it moves around the southwestern periphery of a mid-level ridge over the central subtropical Atlantic. Most of the track guidance has again shifted slightly eastward during the first 48 hours, and the NHC forecast track has been nudged in that direction. The NHC forecast is along the southern edge of the guidance envelope during the first couple of days and is close to the GFS and ECMWF models. After that time, Gonzalo is forecast to turn northward then north-northeastward ahead of a deep-layer trough that approaches the east coast of the United States in about 4 days. Although the track guidance is in general agreement on this scenario, there remains large differences in the forward speed of the cyclone later in the period. The GFS, UKMET, and HWRF showing more north-northeastward acceleration than the ECMWF. The updated NHC track forecast is near the GFS/ECMWF consensus, which is faster than the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 16.8N 60.9W 50 KT 60 MPH 12H 13/1800Z 17.4N 62.5W 55 KT 65 MPH 24H 14/0600Z 18.6N 64.3W 60 KT 70 MPH 36H 14/1800Z 20.2N 65.8W 70 KT 80 MPH 48H 15/0600Z 21.5N 67.0W 75 KT 85 MPH 72H 16/0600Z 23.8N 68.1W 85 KT 100 MPH 96H 17/0600Z 26.0N 67.5W 95 KT 110 MPH 120H 18/0600Z 29.0N 65.5W 90 KT 105 MPH $$ Forecaster Brown