000 WTNT42 KNHC 202044 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 26 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 500 PM AST TUE SEP 20 2016 Karl's center had lost some definition throughout the day, but deep convection has redeveloped near the center late in the afternoon. Dvorak Current Intensity estimates were lowered to 2.5 from TAFB and 2.0 from SAB, and the latest UW-CIMSS ADT estimate is T3.2. A NOAA P-3 flight currently conducting a research mission into Karl has not yet found tropical-storm-force winds, but it has not sampled the entire circulation yet. The initial intensity is therefore held at 35 kt pending additional data from the P-3. The minimum pressure is lowered to 1005 mb based on dropsonde data from the NOAA G-IV jet, which is also flying near Karl. Little to no change is expected in the strength of Karl over the next 24 hours as the influence of an upper low continues to shear out the western side of the storm. The global models indicate that the shear should relax in the next 24 to 36 hours allowing a slight strengthening in that period. As Karl rounds the mid-level ridge it will find itself in a more favorable environment with warm SSTs and lower shear. An increased rate of intensification should take place in the 48 to 72 hour time frame, and Karl is expected to reach hurricane strength by the end of that period. The official intensity forecast has been nudged slightly downward based on the latest guidance, however it is still on the upper end of the guidance spread. The center of Karl continues pushing west near the 20th parallel with an initial motion of 275 at 12 kt. Karl is expected to make a turn toward the west-northwest shortly and should reach the western edge of the subtropical high during the next 48 hours, turning to the northwest by day 2 and to the north by day 4. Karl will then accelerate to the northeast as it gets picked up by the westerlies ahead of an upper level trough. Global model guidance continues to show considerable spread into the day 5 period. The ECMWF is significantly slower than the other models because the upper level trough does not pick up Karl. The official track forecast follows close to the previous forecast and remains near a consensus of the GFS and ECMWF. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 20.1N 55.2W 35 KT 40 MPH 12H 21/0600Z 20.8N 57.0W 35 KT 40 MPH 24H 21/1800Z 22.3N 59.2W 40 KT 45 MPH 36H 22/0600Z 24.1N 61.4W 45 KT 50 MPH 48H 22/1800Z 25.6N 63.5W 55 KT 65 MPH 72H 23/1800Z 28.5N 65.5W 70 KT 80 MPH 96H 24/1800Z 32.5N 61.5W 85 KT 100 MPH 120H 25/1800Z 38.5N 51.0W 80 KT 90 MPH $$ Forecaster Krekeler/Berg