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| #932223 (Received by flhurricane at: 11:00 PM 09.Jul.2018) TCDAT3 Tropical Storm Chris Discussion Number 14 NWS National Hurricane Center Miami FL AL032018 1100 PM EDT Mon Jul 09 2018 Reports from a NOAA Hurricane Hunter aircraft indicate that Chris has changed little in strength during the past several hours. The aircraft has reported maximum flight-level of 63 kt at 700 mb to the southwest of the center, along with a somewhat-uncertain maximum SFMR surface wind estimate of 61 kt. The latest reported central pressure is 995 mb. Based on these, the initial intensity will be held at a possibly generous 60 kt. The aircraft also reported that a partial eyewall of 20-30 n mi diameter has formed, but has not yet been able to close off. Chris has moved little since the last advisory, as it remains trapped in a break in the subtropical ridge. A large mid-latitude trough is forming over eastern Canada and the northeastern United States, and as this system develops southward it should break down the ridge and steer Chris to the northeast after about 12 h, with an increasing forward speed expected thereafter as the tropical cyclone enters the mid-latitude westerlies. Chris should pass east of the Canadian Maritimes in about 72 h, then pass near or over southeastern Newfoundland between 72-96 h. The track guidance generally agrees with this scenario, although some spread remains in the forecast forward speed. The new forecast track is an update of the previous forecast and lies near the various consensus models. The sea surface temperature at NOAA buoy 41002, located 45 n mi southwest of the center of Chris, has dropped to near 25C, and it is possible that the temperatures are colder under the center. This ocean cooling, due to upwelling caused by the slow motion of the storm, has likely slowed the intensification of Chris despite an otherwise favorable environment and storm structure. Significant intensification now appears unlikely until the cyclone actually starts moving. Based on this and the forecast track, the new intensity forecast will delay Chris` intensification into a hurricane until the 18-24 h point. After that, Chris should strengthen until it moves north of the Gulf Stream and starts to merge with a frontal system. Extratropical transition is expected to be complete by 72 h, with the extratropical low gradually decaying as it moves across the north Atlantic. The new intensity forecast follows the overall trend of the intensity guidance except during the first 12 h. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 32.3N 74.3W 60 KT 70 MPH 12H 10/1200Z 32.6N 73.9W 60 KT 70 MPH 24H 11/0000Z 33.5N 72.7W 70 KT 80 MPH 36H 11/1200Z 35.1N 70.4W 80 KT 90 MPH 48H 12/0000Z 37.7N 66.6W 80 KT 90 MPH 72H 13/0000Z 44.0N 59.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 14/0000Z 49.0N 47.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 15/0000Z 52.0N 31.0W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven |
