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#905047 (Received by flhurricane at: 4:55 AM 29.Sep.2017) TCDAT5 Tropical Storm Maria Discussion Number 53 NWS National Hurricane Center Miami FL AL152017 500 AM AST Fri Sep 29 2017 Maria is producing a relatively small cluster of deep convection that is displaced to the east of the center due to 15 kt of westerly shear. Scatterometer data from last evening showed some 45-kt wind vectors south of the center, so Maria`s initial intensity is estimated to be 50 kt, accounting for the low resolution of the ASCAT instruments. Maria will continue to move over waters of at least 26 degrees Celsius for at least the next 24-36 hours, although vertical shear will be increasing over the cyclone fairly soon. The first stages of extratropical transition are likely to begin later today, and baroclinic forcing could allow Maria to regain a little bit of strength, which is shown by both the GFS and ECMWF models over the next couple of days. Maria should be fully extratropical by 48 hours and then be absorbed within a frontal zone a little after 72 hours. Some of the global models, such as the GFS and UKMET, show this absorption occurring sooner than that. Maria is accelerating eastward within the mid-latitude westerlies with an initial motion of 085/18 kt. The cyclone should turn east-northeastward later today, ahead of a mid-latitude trough moving off the northeastern U.S. and Atlantic Canada coast, with acceleration continuing up until the time Maria dissipates. Although the ECMWF model is an outlier and has a slower solution compared to the other guidance, the NHC track forecast remains close to the other models and the various consensus aids. The post-tropical intensity and wind radii forecasts at 48 and 72 h are based on guidance provided by the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 37.2N 63.3W 50 KT 60 MPH 12H 29/1800Z 37.9N 59.0W 55 KT 65 MPH 24H 30/0600Z 39.8N 52.3W 55 KT 65 MPH 36H 30/1800Z 42.1N 45.0W 55 KT 65 MPH 48H 01/0600Z 45.0N 36.8W 50 KT 60 MPH...POST-TROP/EXTRATROP 72H 02/0600Z 51.4N 16.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 03/0600Z...ABSORBED WITHIN A FRONTAL ZONE $$ Forecaster Berg |