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| #941606 (Received by flhurricane at: 10:48 PM 23.Sep.2018) TCDAT2 Tropical Depression Kirk Discussion Number 7 NWS National Hurricane Center Miami FL AL122018 1100 PM AST Sun Sep 23 2018 Kirk is looking increasingly disheveled in satellite imagery. A pair of ASCAT passes between 2300 and 0000 UTC indicated that Kirk has likely opened up into a trough of low pressure and no longer has a closed surface circulation. However, no recent visible imagery or surface observations are available to confirm this. Since the ASCAT passes showed a few 25-30 kt wind vectors on the north side of the alleged circulation, Kirk is being maintained as a 30 kt tropical depression for now. The ASCAT data showed almost no sign of the previous surface center of Kirk, so the initial position was shifted significantly to the west, closer to the wave axis. As a result, the NHC track forecast has also been shifted significantly westward (faster) at all forecast hours, especially from 12-72 h. Whether Kirk is a tropical wave, depression, or storm, it should continue moving rapidly westward for the next couple of days. By mid-week, the system will reach a break in the subtropical ridge which will result in a slower forward speed as it approaches and enters the Caribbean. The NHC track forecast remains on the south side of the guidance envelope, and is closest to the corrected consensus aid, HCCA. It is likely that the fast forward speed is preventing Kirk from becoming better organized and strengthening, and the global models do not suggest that it will slow down substantially for the next couple of days. While it is not explicitly reflected in the forecast, Kirk could dissipate into a tropical wave at any time, if it hasn`t already. By the end of the forecast period, the slower motion of Kirk could allow for some reorganization, however strong vertical wind shear over the Caribbean will likely prevent the system from significantly strengthening. The NHC intensity forecast has been adjusted down, and is now essentially a blend of the global and regional dynamical model forecasts. FORECAST POSITIONS AND MAX WINDS INIT 24/0300Z 9.4N 35.5W 30 KT 35 MPH 12H 24/1200Z 9.8N 39.0W 30 KT 35 MPH 24H 25/0000Z 10.0N 43.2W 35 KT 40 MPH 36H 25/1200Z 10.3N 47.2W 35 KT 40 MPH 48H 26/0000Z 10.6N 50.6W 35 KT 40 MPH 72H 27/0000Z 11.7N 56.2W 35 KT 40 MPH 96H 28/0000Z 13.0N 60.5W 35 KT 40 MPH 120H 29/0000Z 14.0N 65.0W 30 KT 35 MPH $$ Forecaster Zelinsky |
