000 WTPZ42 KNHC 151432 TCDEP2 Tropical Storm Tara Discussion Number 5 NWS National Hurricane Center Miami FL EP222018 1000 AM CDT Mon Oct 15 2018 Tara remains a small, sheared tropical cyclone with convection continuing to go through bursting phases near the low-level center. Extremely cold overshooting cloud tops of -90C to -95C have been occurring just north of the center during the past couple of hours, and the convective cloud shield has gradually been expanding southeastward over the center. Satellite intensity estimates are T3.0/45 kt from TAFB and T2.5/35 kt from SAB, and the most recent objective ADT estimate from UW-CIMSS was T3.1/47 kt. Based on these data, the intensity is conservatively raised to 40 kt. The initial motion estimate is an uncertain 295/01 kt. Tara is expected to only drift toward the west-northwest or northwest for the next couple of days while the small cyclone remains embedded in weak steering currents. The GFS and UKMET models move Tara inland just west of Manzanillo, Mexico, in 36-48 hours, whereas the ECMWF, GFS-FV3, HWRF, HMON, COAMPS-TC, and Canadian models keep the center offshore. For now, the official forecast track follows the consensus models TVCE, HCCA, and FSSE, keeping the center offshore the southwestern coast of Mexico since there appears to be no significant steering mechanism to force the circulation onshore for the next couple of days. After 48 hours, the ridge to the north of Tara is forecast to build westward across central Mexico, forcing the cyclone on a west-northwestward track at a slightly faster forward speed. However, due to continued large spread in the guidance, the track forecast is of low confidence. Moderate easterly to southeasterly shear is forecast by the models to affect Tara for the next 24 hours or so. By 36 hours, the shear is forecast to decrease to less than 5 kt and remain low until 72 hours, which should allow for some modest strengthening to occur... assuming the center remains offshore. The small circulation, low vertical wind shear conditions, and warm ocean temperatures near 30C would typically result in more significant strengthening, but proximity to land and a dry surrounding environment is expected to temper the intensification process somewhat. By days 4 and 5, southwesterly shear forecast to increase to around 20 kt should is expected to induce some slight weakening. The official intensity forecast is similar to but slightly higher than the consensus models HCCA, IVCN, and FSSE, and maintains continuity with the previous forecast. Regardless of how close Tara comes to southwestern Mexico, heavy rainfall will be the primary threat along the coast of southwestern Mexico due to the system's slow motion, and life-threatening flash flooding will be possible in mountainous areas. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 17.6N 104.4W 40 KT 45 MPH 12H 16/0000Z 17.8N 104.6W 45 KT 50 MPH 24H 16/1200Z 17.9N 104.7W 50 KT 60 MPH 36H 17/0000Z 17.9N 105.1W 50 KT 60 MPH 48H 17/1200Z 18.0N 105.7W 55 KT 65 MPH 72H 18/1200Z 18.4N 107.0W 55 KT 65 MPH 96H 19/1200Z 18.9N 108.1W 50 KT 60 MPH 120H 20/1200Z 19.0N 108.1W 45 KT 50 MPH $$ Forecaster Stewart