Issued at 500 PM AST Wed Jul 11 2018 212 WTNT43 KNHC 112047TCDAT3Hurricane Chris Discussion Number 21NWS National Hurricane Center Miami FL AL032018500 PM AST Wed Jul 11 2018The eye of Chris has become a little less distinct and morecloud filled during the past few hours, but the overall cloudpattern remains quite impressive in satellite imagery. Therespective wind radii were adjusted outward based on a 1454 UTCASCAT-A overpass, which included one 65-kt surface wind vector inthe southeastern quadrant. The initial intensity has been loweredslightly to 80 kt based on a blend of Dvorak intensity estimates ofT4.5/77 from both TAFB and SAB, and an ADT estimate of T5.2/95 kt.The initial motion estimate is now 050/22 kt. Little change was madeto the previous advisory track. Chris is now embedded within deepsouthwesterly flow ahead of a broad trough that is diggingsoutheastward along the U.S. Northeast and Mid-Atlantic coasts. Theglobal models are in excellent agreement that the hurricane shouldcontinue to accelerate northeastward for the next 72 hours, passingover or near southeastern Newfoundland in 24-36 hours as a strongextratropical cyclone. In contrast to several previous model runs,the latest NHC guidance shows very little cross-track spread orspeed differences, and is tightly packed about the previous advisorytrack. The new forecast track closely follows the previous forecastand the consensus track models HCCA, TVCN, and FSSE.During next 6 hours or so, Chris will be passing over a oceanthermal ridge consisting of SSTs of more than 28 deg C, which isassociated with the Gulf Stream. As a result, little change instrength is expected during that time. However, by 24 hours andbeyond, the cyclone will be moving over SSTs colder than 12 deg Cand encountering southwesterly vertical wind shear in excess of30 kt, a detrimental combination that will induce rapid weakeningand also result in transition to an extratropical cyclone. The newintensity forecast is a little lower than the various intensitymodel forecasts to account for stronger shear and colder water.FORECAST POSITIONS AND MAX WINDSINIT 11/2100Z 37.8N 65.7W 80 KT 90 MPH 12H 12/0600Z 40.6N 61.9W 75 KT 85 MPH 24H 12/1800Z 44.9N 56.2W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 13/0600Z 48.8N 49.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 13/1800Z 51.9N 40.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 14/1800Z 58.4N 22.6W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 15/1800Z 63.0N 14.0W 35 KT 40 MPH...POST-TROP/EXTRATROP120H 16/1800Z...DISSIPATED$$Forecaster Stewart

More...