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#932442 (Received by flhurricane at: 10:54 PM 11.Jul.2018) TCDAT3 Hurricane Chris Discussion Number 22 NWS National Hurricane Center Miami FL AL032018 1100 PM AST Wed Jul 11 2018 Chris is quickly unraveling, with its eye completely disintegrating a few hours ago and the convective pattern showing the hallmarks of the onset of extratropical transition. Earlier microwave data actually showed that the hurricane had a concentric eyewall structure, but the mid-level eye was already being stripped away from the low-level center due to increasing southwesterly shear. Chris`s initial intensity is set at 75 kt based on a blend of final T- and CI-numbers from TAFB and SAB. The hurricane is accelerating toward the northeast with an initial motion of 050/25 kt, and the acceleration is expected to continue for the next 48 hours while the cyclone moves ahead of a deep-layer trough located over eastern Canada. After 48 hours, Chris is forecast to slow down to the south of Iceland when it interacts with another deep-layer low. The track guidance is tightly clustered very close to the previous official forecast during the first 72 hours, with only a little more model spread and deviation from the previous forecast at 96 hours. Therefore, the only change to the updated NHC track forecast is to slow down the storm a little on day 4 while it`s located south of Iceland. Chris may still exist on day 5, but there`s too much uncertainty among the models to extend the official forecast at this point. Chris is currently moving over a few warm eddies along the Gulf Stream, but the hurricane`s center will move across the North Wall within the next 6 hours and head toward much colder waters. Vertical shear will also be increasing further over the next 24 hours, and Chris is expected to be fully embedded within a frontal zone within 18-24 hours. The NHC official forecast calls for Chris to complete extratropical transition just before the center reaches extreme southeastern Newfoundland within 24 hours, and the cyclone`s intensity should gradually decrease while it moves across the North Atlantic. The intensity forecast is close to the tropical model guidance for the first 12-24 hours but then sides closer to the GFS and ECMWF guidance during the remainder of the forecast. Chris`s wind radii have been adjusted slightly based on a 0034 UTC ASCAT pass. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 39.6N 63.0W 75 KT 85 MPH 12H 12/1200Z 42.6N 59.2W 65 KT 75 MPH 24H 13/0000Z 46.9N 52.9W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 13/1200Z 50.2N 44.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 14/0000Z 53.1N 35.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 15/0000Z 59.6N 21.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 16/0000Z 62.0N 15.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 17/0000Z...DISSIPATED $$ Forecaster Berg |