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| #875286 (Received by flhurricane at: 10:52 PM 18.Sep.2016) TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 1100 PM AST SUN SEP 18 2016 Karl is a poorly organized tropical storm. Satellite data indicate that the low-level center is exposed to the southwest of a few patches of deep convection. The initial intensity is again held at 35 kt, in agreement with the earlier scatterometer data and a Dvorak classification from TAFB. The cyclone continues to struggle in an environment of southwesterly shear and dry air. In fact, total precipitable water imagery shows dry air wrapping around the west and south sides of the circulation. The models indicate that the shear should lower on Monday, and remain relatively light during the next several days. Since Karl is expected to track over progressively warmer waters, between 28-30 deg C, and move into a more conducive atmospheric environment, strengthening seems likely. The NHC intensity forecast is largely an update of the previous one, but it is a touch lower at the 12-h point given the current poor initial structure of Karl. This forecast is in best agreement with the SHIPS model. The system is moving westward at 13 kt, and that general motion should continue for the next 12-24 hours as Karl remains on the south side of a subtropical ridge over the central Atlantic. A west-northwestward motion is expected to begin by Monday night, followed by a turn to the northwest by mid-week when the cyclone moves toward a weakness in the ridge. Although the models agree on the overall scenario, there is a fair amount of spread by the end of the forecast period. The NHC track forecast is slightly faster than the model consensus, giving a little more weight to the GFS and ECMWF models. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 18.3N 46.3W 35 KT 40 MPH 12H 19/1200Z 18.5N 48.3W 35 KT 40 MPH 24H 20/0000Z 19.1N 50.9W 40 KT 45 MPH 36H 20/1200Z 19.8N 53.4W 45 KT 50 MPH 48H 21/0000Z 20.7N 55.9W 50 KT 60 MPH 72H 22/0000Z 23.1N 60.9W 60 KT 70 MPH 96H 23/0000Z 26.5N 65.0W 70 KT 80 MPH 120H 24/0000Z 28.8N 66.9W 80 KT 90 MPH $$ Forecaster Cangialosi |
