000 WTPZ44 KNHC 220240 TCDEP4 Tropical Depression Nine-E Discussion Number 3 NWS National Hurricane Center Miami FL EP092017 1000 PM CDT Fri Jul 21 2017 Recent microwave images suggest that Tropical Depression Nine-E has formed a small inner core with good curvature of the low cloud lines. However, deep convection near this feature is currently minimal, with most of the convection well away from the center over the northwestern quadrant. Satellite intensity estimates are in the 25-35 kt range, and based on these and the current state of the central convection, the initial intensity remains 30 kt. The cyclone has good outflow in all directions. The initial motion is 280/12. The depression is south of a mid-level ridge extending from Mexico westward into the northeastern Pacific just west of the Baja California peninsula. This pattern should steer the cyclone generally west-northwestward to northwestward for the next three days or so. After that time, the ridge is forecast to strengthen a little, which should give the tropical cyclone a more westward motion. The track guidance is in good agreement with this scenario, and the new forecast track is similar to the old forecast. This forecast, which lies just north of the various consensus models, keeps the core of the cyclone well south of the coast of Mexico at this time. The environment looks very favorable for strengthening, with the depression forecast to be in light vertical shear and over waters of 28-29C for at least the next 4 days. Based on this, a period of rapid intensification seems likely, but when this will occur is not clear. The intensity guidance shows generally slow strengthening for the next 36 h, and the SHIPS Rapid Intensification Index is not unusually high through 36 h. However, the aforementioned inner core suggests that rapid intensification could begin if the convection concentrates around this feature. Given the uncertainty, the intensity forecast is changed little since the previous advisory, showing the system becoming a hurricane just before 48 h and getting to near major hurricane strength by the end of the period. This forecast is above the guidance through 72 h, then is in good agreement with the SHIPS model. It is possible that the current forecast intensities may be too high during the first 36 h and not high enough later in the forecast. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 9.4N 95.7W 30 KT 35 MPH 12H 22/1200Z 9.7N 97.3W 40 KT 45 MPH 24H 23/0000Z 10.7N 99.3W 50 KT 60 MPH 36H 23/1200Z 11.8N 101.0W 60 KT 70 MPH 48H 24/0000Z 12.8N 102.5W 70 KT 80 MPH 72H 25/0000Z 15.0N 105.5W 80 KT 90 MPH 96H 26/0000Z 16.5N 108.5W 90 KT 105 MPH 120H 27/0000Z 18.0N 112.0W 95 KT 110 MPH $$ Forecaster Beven