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Potential Tropical Cyclone Eighteen Forecast Discussion Number 2
2017-10-28 04:40:58| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Fri Oct 27 2017 000 WTNT43 KNHC 280240 TCDAT3 Potential Tropical Cyclone Eighteen Discussion Number 2 NWS National Hurricane Center Miami FL AL182017 1100 PM EDT Fri Oct 27 2017 Satellite imagery shows that the disturbance over the northwestern Caribbean Sea is gradually becoming better organized with increasing convective banding in the western semicircle. However, experimental shortwave infrared data from GOES-16 appear to show the presence of multiple low cloud swirls, and it is unclear if the definition of the center has improved to the point where the system has become a tropical cyclone. Thus, the disturbance remains a potential tropical cyclone at this time. There are no recent observations of the winds near the center, so the initial intensity remains 35 kt based on continuity from the previous advisory. The initial motion is an uncertain 005/6. A deep-layer trough and developing frontal low over the northeastern United States are expected to cause the disturbance to turn northeastward and accelerate during the next 24 h, with a fast motion toward the northeast continuing until the disturbance is absorbed by the mid-latitude system. The track guidance is generally in good agreement with this scenario, although there remains some cross-track spread due mainly to the uncertain center position. The new forecast track is similar to the previous track and is in best agreement with the HFIP Corrected Consensus model. Environmental conditions appear at least somewhat favorable for intensification during the next 48 h, with light to moderate shear and strong upper-level divergence over the system. After that time, the system is expected to be absorbed into the aforementioned mid-latitude system and become a trough rotating around the larger circulation. The new intensity forecast is nudged upward slightly from the previous forecast and now shows a peak intensity of 50 kt before absorption. However, the forecast lies at the lower edge of the intensity guidance, and if the system can develop a better- defined inner core it could strengthen more than currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 18.2N 84.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 28/1200Z 20.1N 83.4W 40 KT 45 MPH 24H 29/0000Z 22.9N 81.1W 45 KT 50 MPH...INLAND 36H 29/1200Z 26.2N 77.4W 45 KT 50 MPH...OVER WATER 48H 30/0000Z 30.8N 73.0W 50 KT 60 MPH 72H 31/0000Z...ABSORBED BY EXTRATROPICAL LOW $$ Forecaster Beven
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