000 WTPZ44 KNHC 300247 TCDEP4 Potential Tropical Cyclone Fourteen-E Discussion Number 2 NWS National Hurricane Center Miami FL EP142017 900 PM MDT Tue Aug 29 2017 Satellite images indicate that the disturbance just off the southwest coast of Mexico is gradually becoming better organized. The system is developing some banding features, especially over the western semicircle. However, the circulation remains broad and there is no indication of a well-defined center at this time. The initial wind speed is held at 25 kt, in agreement with a Dvorak classification from TAFB. The environmental conditions are conducive for the disturbance to strengthen, and it will likely become a tropical storm on Wednesday. Additional strengthening seems likely through about 72 hours, and it is possible that the disturbance could reach hurricane strength. After that time, however, decreasing SSTs and drier air should end the strengthening trend and cause weakening. The NHC intensity forecast lies near the high end of the guidance, and it is very similar to the previous forecast. The initial motion of the system is difficult to determine since there is no clear center, but satellite fixes suggest that the disturbance is moving northwestward at 9 kt. A slower northwestward to north-northwestward motion is expected during the next 2 to 3 days, followed by a turn to the left beyond that time when the system moves on the south side of a mid-level ridge over the western United States. The models have shifted to the east this cycle, and the new NHC track forecast has been adjusted in that direction. This forecast takes the center of the system close to Baja California Sur in the 48- to 72-h time frame. Based on the new forecast, the government of Mexico has expanded the Hurricane Watch northward on the west coast of Baja California Sur. It is important to note that very heavy rain is possible outside of the watch/warning area in southwestern Mexico. These rains could cause life-threatening flooding and mudslides. In addition, wind gusts to tropical-storm-force are possible along the coast of Michoacan, Colima and Jalisco states through early Wednesday due to the system's large circulation. The National Hurricane Center now has the option to issue advisories, watches, and warnings for disturbances that are not yet a tropical cyclone, but which pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours. Under previous policy this was not possible. These systems are known as Potential Tropical Cyclones in advisory products and are numbered from the same list as depressions. Because of the threat to Baja California Sur, advisories are being issued on Potential Tropical Cyclone Fourteen-E. Advisory packages will continue until the threat of tropical-storm-force winds for land areas sufficiently diminishes, although if the system becomes a tropical cyclone, the normal rules for discontinuing advisories would apply. Users should be aware that forecast uncertainty for disturbances is generally larger than for tropical cyclones, especially beyond 48-72 hours. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 17.7N 107.9W 25 KT 30 MPH...POTENTIAL TROP CYCLONE 12H 30/1200Z 18.8N 108.6W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 24H 31/0000Z 19.7N 109.2W 35 KT 40 MPH...TROPICAL STORM 36H 31/1200Z 21.0N 109.8W 45 KT 50 MPH 48H 01/0000Z 22.1N 110.4W 55 KT 65 MPH 72H 02/0000Z 24.1N 112.2W 60 KT 70 MPH 96H 03/0000Z 25.7N 114.8W 45 KT 50 MPH 120H 04/0000Z 27.3N 117.5W 30 KT 35 MPH $$ Forecaster Cangialosi