000 WTPZ41 KNHC 131435 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 AM PDT WED AUG 13 2014 Deep convection has continued to increase with cloud tops of -80C to -84C noted just west of low-level center. Satellite intensity estimates are a consensus T2.5/35 kt from TAFB, SAB, and UW-CIMSS ADT. An earlier ASCAT overpass also indicated surface winds near 34 kt. Based on these data, the depression has been upgraded to Tropical Storm Karina. Karina is moving westward at 13 kt along the southwestern periphery of a strong deep-layer subtropical ridge anchored over the south-central and southwestern United States. The ridge is forecast by the global models to build westward to the north and northwest of the cyclone, which should keep Karina on a basic westward motion throughout the 5-day period. The model guidance envelope has shifted a little to the south with increasing spread, especially beyond 72 hours. This is mainly due to the significant southward shift by the ECMWF model, which shows a much weaker system being steered more southwestward by moderate northeasterly trade wind flow. The ECMWF model is considered to be an outlier at this time, and the official track forecast is just a little faster than the previous advisory and lies near the consensus model TCVE. Karina is experiencing northeasterly vertical wind shear of 12-14 kt. Despite these modest shear conditions, the convective cloud pattern of Karina has continued to develop into a classic hooked band appearance, plus a small central dense overcast feature. Microwave satellite data also suggests that the inner core wind field has tightened somewhat up since the previous advisory. With the wind shear currently affecting the system forecast to slowly subside over the next 4 to 5 days while the cyclone is over 28-29C SSTs, steady intensification appears likely. This development scenario is consistent with the trend of all of the NHC model guidance, and the NHC official intensity forecast indicates this by making Karina a hurricane by 48 hours, which is higher than the ICON intensity consensus model and closer to the SHIPS model. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 17.2N 111.0W 35 KT 40 MPH 12H 14/0000Z 17.4N 112.8W 45 KT 50 MPH 24H 14/1200Z 17.5N 115.3W 55 KT 65 MPH 36H 15/0000Z 17.6N 117.6W 60 KT 70 MPH 48H 15/1200Z 17.8N 120.0W 65 KT 75 MPH 72H 16/1200Z 18.3N 124.1W 75 KT 85 MPH 96H 17/1200Z 18.5N 128.0W 75 KT 85 MPH 120H 18/1200Z 18.5N 131.1W 70 KT 80 MPH $$ Forecaster Stewart