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Subtropical Storm Joyce Forecast Discussion Number 3
2018-09-13 10:58:45| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Sep 13 2018 024 WTNT45 KNHC 130858 TCDAT5 Subtropical Storm Joyce Discussion Number 3 NWS National Hurricane Center Miami FL AL102018 500 AM AST Thu Sep 13 2018 Joyce is still co-located with an upper-level low, and the most recent TAFB intensity classification was still a subtropical type. Furthermore, there has been no discernible increase of convection near the center of the cyclone, and cloud tops have actually warmed over the past few hours. Therefore, Joyce is still classified as subtropical for this advisory. Since the cyclone hasn't changed much in organization, the initial intensity has been held at 40 kt based on the TAFB subtropical intensity estimate, but this is still possibly generous. Joyce's struggle to maintain deep convection bodes poorly for its intensification prospects, considering that the shear is forecast by the global models to increase considerably over the next few days. SHIPS, LGEM, and the global models continue to show Joyce changing little in strength over the next few days until the system dissipates by early next week. The HWRF and HMON models are still outliers in showing substantial intensification, but even these models aren't quite as aggressive in strengthening Joyce as they were previously. The NHC forecast continues to favor the statistical guidance and is just below the intensity consensus at most forecast hours because it is frankly hard to believe that Joyce will become a hurricane in 48 h based on its current appearance. Joyce is still moving slowly southwestward with an initial motion of 220/5 kt. The global models remain in fairly good agreement that Joyce will move slowly southwestward for the next day or so as the storm remains in light steering flow. A turn toward the south will likely occur as Helene approaches from the southeast, followed by a quick turn northeastward once the larger tropical cyclone passes by. Joyce should then accelerate quickly northeastward ahead of a mid-latitude trough before dissipating southwest of the Azores. Little change was made to the official track forecast which is near the middle of the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 33.8N 43.1W 40 KT 45 MPH 12H 13/1800Z 33.3N 43.8W 40 KT 45 MPH 24H 14/0600Z 32.6N 44.2W 45 KT 50 MPH 36H 14/1800Z 32.0N 44.0W 45 KT 50 MPH 48H 15/0600Z 32.1N 43.2W 45 KT 50 MPH 72H 16/0600Z 34.6N 39.4W 40 KT 45 MPH 96H 17/0600Z 37.0N 32.5W 40 KT 45 MPH 120H 18/0600Z...DISSIPATED $$ Forecaster Zelinsky
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