000 WTPZ41 KNHC 181441 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 23 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 AM PDT MON AUG 18 2014 The cloud pattern associated with Karina has not changed much during the past 2 or 3 days, and still consists of an area of deep convection with the center on the northern edge due to shear. This was confirmed by an AMSU pass earlier today. Given that the cloud pattern has not changed, the initial intensity is kept at 40 kt. Karina has the chance to slightly strengthen since the circulation is moving over warmer waters and into weaker shear. By the end of the forecast period, the outflow from larger Tropical Depression 12-E to the northeast should induce stronger shear and prevent additional strengthening. Best estimate of the initial motion is 255 degrees at 8 kt. Karina is trapped south of a strong subtropical ridge, and this pattern will keep the cyclone moving slowly south of due west or to the west for the next 2 to 3 days. The confidence in this portion of the forecast is high with good guidance agreement. After that time, Karina's motion will be dominated by the larger-than- normal TD 12-E, which is forecast to pass to the northeast. This should result in a collapse of the steering flow near Karina and very little motion of the cyclone. By the end of the period Karina should begin to turn slowly to the northeast steered by the southwesterly flow on the south side of TD 12-E. This later portion of the forecast is much less certain due to the large guidance spread. On the other hand, all dynamical models agree on the turn to the northeast. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 16.8N 132.4W 40 KT 45 MPH 12H 19/0000Z 16.5N 133.4W 40 KT 45 MPH 24H 19/1200Z 16.3N 134.5W 45 KT 50 MPH 36H 20/0000Z 16.3N 135.5W 50 KT 60 MPH 48H 20/1200Z 16.3N 136.2W 50 KT 60 MPH 72H 21/1200Z 16.5N 136.5W 45 KT 50 MPH 96H 22/1200Z 16.5N 136.5W 45 KT 50 MPH 120H 23/1200Z 17.5N 135.5W 45 KT 50 MPH $$ Forecaster Avila