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Tropical Storm Rose Forecast Discussion Number 7
2021-09-20 22:34:04| National Hurricane Center (Atlantic)
Issued at 500 PM AST Mon Sep 20 2021 000 WTNT42 KNHC 202033 TCDAT2 Tropical Storm Rose Discussion Number 7 NWS National Hurricane Center Miami FL AL172021 500 PM AST Mon Sep 20 2021 Satellite images show that Rose hasn't changed much during the past several hours, with the center on the northern side of the cloud shield. The last microwave pass from a few hours ago showed that the mid- and low-level centers of the cyclone remained 60-90 n mi apart, which is probably a sign that it isn't strengthening. The initial wind speed remains 35 kt based on continuity, and hopefully scatterometer data will be available for the next advisory due to the recent high bias of the conventional satellite estimates. The window for strengthening of the tropical cyclone is closing soon due to increasing shear and likely intrusions of dry mid-level air. These factors should cause the storm to start a weakening trend sometime tomorrow. The long-term future of Rose doesn't look golden either due to further increasing shear from an incoming upper- level trough. The new forecast is just a shade lower than the previous one, near the model consensus, with Rose likely sinking to a depression in a few days and degenerating to a remnant low by day 5. The initial motion remains northwestward at about 14 kt. Rose is is likely to continue moving in that general direction during the next couple of days around the southwestern and western periphery of a strong subtropical ridge. Beyond that time, guidance is coming into good agreement on a mid- to upper-level trough over the north-central Atlantic causing the cyclone to recurve to the north, northeast and even east-northeastward by the weekend. While the models don't agree on how sharp of a turn will occur, they are at least consistent that this trough will take the storm into a hostile environment and decay. The new forecast is again adjusted well to northeast at long range, and still might not be far enough to the east. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 18.4N 34.4W 35 KT 40 MPH 12H 21/0600Z 20.0N 35.6W 40 KT 45 MPH 24H 21/1800Z 21.8N 36.7W 35 KT 40 MPH 36H 22/0600Z 23.3N 37.8W 35 KT 40 MPH 48H 22/1800Z 24.5N 38.9W 30 KT 35 MPH 60H 23/0600Z 26.0N 39.9W 30 KT 35 MPH 72H 23/1800Z 27.3N 40.2W 30 KT 35 MPH 96H 24/1800Z 29.2N 38.8W 25 KT 30 MPH 120H 25/1800Z 31.5N 34.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Blake
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