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Subtropical Storm Rebekah Forecast Discussion Number 3
2019-10-31 09:33:46| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Oct 31 2019 000 WTNT44 KNHC 310833 TCDAT4 Subtropical Storm Rebekah Discussion Number 3 NWS National Hurricane Center Miami FL AL192019 500 AM AST Thu Oct 31 2019 Rebekah's cloud pattern has eroded significantly since the previous advisory and only a narrow band of fragmented convection remains in the northeastern quadrant. There are no signs of any upper-level anticyclonic outflow, so the cyclone will retain subtropical status. Earlier ASCAT-A/B/C overpasses indicated several 38-39 kt surface wind vectors in the southern semicircle and given that Rebekah is now moving at a faster forward speed, the intensity remains at 40 kt despite the degraded convective pattern. The initial motion estimate is 065/18 kt. Rebekah is forecast to move east-northeastward to eastward around the southeastern periphery of a larger non-tropical low pressure system for the next day or two before dissipating by 48 hours. The model guidance has shifted northward significantly and the official forecast has been moved in that direction as well, but not as far north nor as fast as the model consensus, lying closer to a blend of the GFS and ECMWF model solutions. Rebekah will be moving over cooler waters that are less than 20 deg C and into a stronger vertical wind shear regime by 12 h and beyond. This combination of unfavorable dynamic and thermodynamic conditions should cause the cyclone to steady weaken and become a post-tropical cyclone in 24 h or less, with dissipation expected by 48 h. Although the center of Rebekah is expected to pass north of the Azores, those islands could still receive gusty winds and locally heavy rainfall, especially on the southward-facing slopes of elevated terrain. Since Rebekah is not expected to be a tropical or subtropical cyclone when it nears the Azores, hazard information can be found in regular products issued by the Portuguese Institute for the Sea and Atmosphere (IPMA) for those islands at https://www.ipma.pt/pt/index.html. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 39.7N 36.7W 40 KT 45 MPH...SUBTROPICAL STORM 12H 31/1800Z 40.6N 33.7W 40 KT 45 MPH...SUBTROPICAL STORM 24H 01/0600Z 40.6N 29.4W 35 KT 40 MPH...POST-TROP/EXTRATROP 36H 01/1800Z 40.3N 25.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 02/0600Z...DISSIPATED $$ Forecaster Stewart
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