273 WTPZ41 KNHC 300240 TCDEP1 Tropical Storm Sergio Discussion Number 3 NWS National Hurricane Center Miami FL EP212018 1000 PM CDT Sat Sep 29 2018 Satellite images indicate that Sergio has become better organized during the past several hours with more concentrated convection near the center. Intensity estimates are slightly higher than the past advisory, so the initial wind speed is set to 40 kt, closest to the CIMSS SATCON. The storm should be in a low-shear, warm-water, and high-moisture environment for the next 2 or 3 days. While there are no signs of an inner core forming yet, that usually doesn't stop steady intensification, and rapid strengthening is a distinct possibility in a day or two. Thus the intensity forecast is raised from the previous one and is close to the consensus. Although there are a number of reliable models showing a higher peak intensity, an uncertain environment at long range leads me to a more conservative forecast. It would not be surprising at all if my prediction ended up being too low, given the intense nature of this eastern Pacific hurricane season. The initial motion is close to the prevous one, 275/9. Sergio should be steered generally westward for the next two or three days by the subtropical ridge over Mexico. After that time, the cyclone is forecast to approach a weakness in the ridge caused by a large mid- to upper-level trough over California, and this should lead to a turn toward the northwest. Similar to the previous advisory, the track guidance has shifted slightly south and west, so the official forecast is nudged in that direction at most time periods. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 12.3N 103.3W 40 KT 45 MPH 12H 30/1200Z 12.4N 104.7W 50 KT 60 MPH 24H 01/0000Z 12.3N 106.9W 65 KT 75 MPH 36H 01/1200Z 12.0N 109.1W 75 KT 85 MPH 48H 02/0000Z 11.8N 111.1W 90 KT 105 MPH 72H 03/0000Z 12.9N 114.8W 100 KT 115 MPH 96H 04/0000Z 15.0N 117.8W 100 KT 115 MPH 120H 05/0000Z 17.0N 120.0W 95 KT 110 MPH $$ Forecaster Blake