000 WTPZ44 KNHC 250858 TCDEP4 Hurricane Hilary Discussion Number 16 NWS National Hurricane Center Miami FL EP092017 300 AM MDT Tue Jul 25 2017 Hilary's compact, symmetric, inner core continues to become better defined on satellite imagery. Microwave imagery suggests that the eye is quite small, less than 10 n mi in diameter, with little evidence of vertical tilt of the vortex. The current intensity estimate is now 90 kt in agreement with a Dvorak estimate from the NESDIS SAB. Hilary should be in a moist air mass and over a warm ocean for the next couple of days. Dynamical guidance predicts some increase in northerly shear over the cyclone in 1- to 2-days, but probably not enough of an increase to impede at least some additional strengthening. The official intensity forecast calls for Hilary to become a major hurricane in 12 hours or so and reach a peak in a day or so. This is in good agreement with the latest Florida State University Superensemble (FSSE) prediction. Later in the forecast period, gradually cooling sea surface temperatures should induce slow weakening. The initial motion estimate remains west-northwestward, or 290/9 kt. A mid-tropospheric ridge extending westward from the southwestern United States would cause Hilary to continue on its west-northwestward track for the next several days. In a few days, however, Hilary is likely to pass close to Hurricane Irwin. The current thinking is that the circulation of Hilary will dominate so that little influence on Hilary's track, due to binary interaction with Irwin, will occur. On the other hand, the latter tropical cyclone is expected to begin rotating around Hilary's circulation later in the forecast period (please refer to the Forecast Discussion on Irwin for additional information). The official track forecast is quite close to the simple consensus TVCN, and to the corrected consensus predictions, HCCA and FSSE. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 15.3N 106.7W 90 KT 105 MPH 12H 25/1800Z 15.8N 108.2W 100 KT 115 MPH 24H 26/0600Z 16.3N 110.4W 105 KT 120 MPH 36H 26/1800Z 16.8N 112.6W 105 KT 120 MPH 48H 27/0600Z 17.4N 114.8W 100 KT 115 MPH 72H 28/0600Z 18.6N 118.7W 85 KT 100 MPH 96H 29/0600Z 19.5N 122.5W 75 KT 85 MPH 120H 30/0600Z 20.0N 126.0W 65 KT 75 MPH $$ Forecaster Pasch