000 WTPZ41 KNHC 150833 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 200 AM PDT FRI AUG 15 2014 Karina continues to experience 20-25 kt of easterly vertical wind shear, which has caused the center to become partly exposed on the eastern side of the deep convection. Satellite intensity estimates are 65 kt from SAB and 55 kt from TAFB. The initial intensity is decreased to 60 kt, and this may a little generous. The initial motion is now 275/10. Karina remains on the south side of a mid-level ridge that extends from the southwestern United States westward over the Pacific. This feature should steer the storm generally westward to west-northwestward for the next 2-3 days. After that time, the guidance becomes divergent, partly due to how the models show Karina interacting with other nearby tropical disturbances. The ECMWF and Canadian models forecast a low pressure area east of Karina causing the cyclone to turn generally west- southwestward. The UKMET and NAVGEM also show a low to the east. However, they forecast it to have less influence on Karina, with the UKMET showing a continued westward track and the NAVGEM showing a turn toward the north. The GFS shows less development east of Karina and instead forecasts the cyclone to interact with a disturbance to the southwest, which causes Karina to continue westward to west-northwestward. Given the uncertainty, the new forecast track will follow the previous forecast in showing a west-southwestward turn in best agreement with the ECMWF, HWRF, and the Florida State Superensemble models. The new track lies to the south of the center of the guidance envelope and the other consensus models. The dynamical models suggest the current shear could continue for another 24-30 hours. Based on this and the current structure of the storm, the early part of the intensity forecast is revised significantly downward from the previous advisory. After that time, the forecast remains tricky. The shear is expected to decrease while Karina moves over sea surface temperatures of near 26C. This could allow Karina to re-intensify as forecast by the GFDL and the Navy COAMPS models. However, any deviation north of the forecast track would take the system over colder water, which would prevent strengthening. The possible interaction with the other disturbances would also hinder re-intensification, and the Canadian model shows Karina starting to get absorbed by the eastern disturbance near the end of the forecast period. Since there are so many possibilities, the latter part of the intensity forecast is low confidence. It calls for Karina to maintain a 50 kt intensity from 24-120 hours, which is stronger than much of the guidance. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 17.2N 119.1W 60 KT 70 MPH 12H 15/1800Z 17.6N 120.7W 55 KT 65 MPH 24H 16/0600Z 18.1N 122.9W 50 KT 60 MPH 36H 16/1800Z 18.4N 125.0W 50 KT 60 MPH 48H 17/0600Z 18.4N 127.0W 50 KT 60 MPH 72H 18/0600Z 18.0N 131.0W 50 KT 60 MPH 96H 19/0600Z 17.5N 134.0W 50 KT 60 MPH 120H 20/0600Z 17.0N 136.5W 50 KT 60 MPH $$ Forecaster Beven