Tropical Cyclone Discussion
180 WTPZ43 KNHC 270855 TCDEP3 Tropical Depression Eighteen-E Discussion Number 1 NWS National Hurricane Center Miami FL EP182026 300 AM CST Sun Sep 27 2026 The tropical disturbance located south of Mexico, formerly Invest 90E, has become better organized based on satellite imagery over the last several hours. Scatterometry data from around 0300 UTC depicts a closed circulation, with the system moving into a favorable environment for further development. Subjective Dvorak intensity analysis from TAFB also rated the system at 2.0/30 kt. Therefore, advisories have begun for Tropical Depression Eighteen-E. The initial motion is somewhat uncertain since the cyclone has only recently formed, but the motion estimate is around 285/9 kt. Track guidance is in good agreement on steering this system generally to the west-northwest over the next several days, with an increase in forward speed as it runs south of a mid-level high over Mexico. The current NHC track forecast generally falls within the middle of the guidance envelope, favoring HCCA in particular. SHIPS guidance suggests that vertical wind shear may be an inhibiting factor for development for the first 24 h, before the Depression is expected to gradually strengthen as SSTs remain warm and mid-level moisture appears favorable. There is some uncertainty with regards to SSTs due to colder waters potentially being churned up in the wake of Hurricane Polo, so the current intensity forecast is a little conservative at first, before depicting gradual strengthening through the late weekend onward. This still falls around the median of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 27/0900Z 12.2N 99.1W 30 KT 35 MPH 12H 27/1800Z 12.7N 99.6W 30 KT 35 MPH 24H 28/0600Z 13.2N 100.8W 35 KT 40 MPH 36H 28/1800Z 13.8N 102.2W 45 KT 50 MPH 48H 29/0600Z 14.7N 104.1W 55 KT 65 MPH 60H 29/1800Z 15.7N 105.9W 65 KT 75 MPH 72H 30/0600Z 16.9N 107.7W 75 KT 85 MPH 96H 01/0600Z 18.7N 109.6W 80 KT 90 MPH 120H 02/0600Z 19.7N 110.3W 75 KT 85 MPH