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Hurricane Chris Forecast Discussion Number 22
2018-07-12 04:46:56| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Wed Jul 11 2018 163 WTNT43 KNHC 120246 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
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