ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014 800 AM PDT WED SEP 24 2014 Convection associated with the area of low pressure located south of Mexico has increased and persisted overnight. The convection is not extremely well organized due to strong northeasterly shear, however Dvorak T-numbers of 2.0 from both SAB and TAFB suggest that the system has enough organization to be classified as a tropical depression. The shear is causing the convection to be displaced to the south and southwest of the low-level center. The initial intensity is set at 30 kt, which is in agreement with the latest Dvorak classifications and earlier ASCAT data. Strong upper-level winds over the cyclone are expected to continue during the next 24 hours or so. After that time, the depression is forecast to move into an area of decreasing shear and some gradually strengthening is predicted. Late in the period, the cyclone will move into a less favorable thermodynamic environment and weakening should commence. The NHC intensity forecast is close to the SHIPS guidance. The initial motion estimate is 285/12 kt. The depression should move west-northwestward to the south of a mid-level ridge over Mexico during the next several days. After 72 hours, the cyclone will approach a weakness in the ridge caused by a mid-latitude trough that will be moving into California. This should cause the cyclone to slow down and turn northwestward by days 4 and 5. The track guidance is in good agreement with this scenario and the NHC track is a blend of the latest ECMWF and GFS model solutions. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 15.0N 105.5W 30 KT 35 MPH 12H 25/0000Z 15.7N 107.0W 30 KT 35 MPH 24H 25/1200Z 16.7N 109.0W 30 KT 35 MPH 36H 26/0000Z 17.7N 110.9W 35 KT 40 MPH 48H 26/1200Z 18.6N 112.7W 40 KT 45 MPH 72H 27/1200Z 20.0N 115.0W 45 KT 50 MPH 96H 28/1200Z 21.0N 116.0W 45 KT 50 MPH 120H 29/1200Z 22.0N 116.5W 40 KT 45 MPH $$ Forecaster Brown NNNN