000 WTPZ41 KNHC 160838 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 200 AM PDT SAT AUG 16 2014 Karina continues to be affected by about 15 kt of easterly vertical wind shear, with the low-level center located just to the northeast of a burst of convection with cloud tops colder than -80C. Satellite intensity estimates are 45 kt from TAFB and 35 kt from SAB. In addition, a recent ASCAT overpass showed 35-40 kt winds about 40 n mi north of the center. Based on these data, the initial intensity remains 40 kt. The initial motion is now 285/9, with Karina continuing to be steered by a subtropical ridge to the north. This ridge will build westward during the next couple of days, followed by an amplification of a ridge well north of the Hawaiian Islands. These developments should result in Karina turning westward later today and then turning a little south of due west during the middle of the forecast period. The steering current are expected to collapse after 72 hours as a mid/upper-level trough likely develops off the west coast of North America and other areas of disturbed weather develop east and west of the cyclone. During this time, the GFS and Canadian models forecast a loop back to the east, the ECMWF and UKMET models forecast a slow westward motion, and the NAVGEM and GFS ensemble mean forecast a slow northward motion. The official forecast track compromises between these forecasts by showing a westward drift. Overall, the new track is again similar to the old track and near the multi-model consensus. The large-scale models forecast the shear to decrease during the next 48 hours or so. However, Karina will be moving over gradually decreasing sea surface temperatures, and the forecast track keeps the center near the 26C isotherm after 48 hours. In the short term, Karina is expected to weaken a little more. While the official forecast keeps the system as a tropical storm, an alternate scenario is shown by the SHIPS and LGEM models, which forecast it to weaken to a depression. After 48 hours, the guidance suggests Karina could re-intensify if it is not absorbed by one of the nearby disturbances. The latter part of the official forecast reflects this by showing modest strengthening. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 18.1N 122.9W 40 KT 45 MPH 12H 16/1800Z 18.2N 124.4W 35 KT 40 MPH 24H 17/0600Z 18.2N 126.4W 35 KT 40 MPH 36H 17/1800Z 18.0N 128.4W 35 KT 40 MPH 48H 18/0600Z 17.6N 130.1W 35 KT 40 MPH 72H 19/0600Z 16.5N 132.5W 40 KT 45 MPH 96H 20/0600Z 16.5N 133.5W 40 KT 45 MPH 120H 21/0600Z 16.5N 134.0W 45 KT 50 MPH $$ Forecaster Beven