Tropical Depression Rose Forecast Discussion Number 12
ActuCyclone
22 septembre 2021
942 WTNT42 KNHC 220238 TCDAT2 Tropical Depression Rose Discussion Number 12 NWS National Hurricane Center Miami FL AL172021 1100 PM AST Tue Sep 21 2021 Strong northwesterly shear has continued to take a toll on Rose this evening with the remaining deep convection becoming further separated from the low-level center. Unfortunately Rose fell within the gaps of the ASCAT satellite instruments this evening, so there has been no recent scatterometer data. Dvorak T-numbers from TAFB and SAB have continued to decline, and these subjective estimates support lowering Rose's initial intensity to 30 kt. The environment ahead of the cyclone is expected to remain quite hostile with moderate westerly to northwesterly shear and a dry mid-level atmosphere. Simulated satellite imagery from the global models suggest Rose will continue to produce bursts of convection over the eastern portion of its circulation during the next few days which could allow it remain a tropical cyclone during that time. Alternatively, the shear and dry air could cause the system to degenerate into a remnant low much sooner. The latest NHC intensity forecast is similar to the previous advisory and calls for little overall change in strength during the next couple of days, followed by degeneration into a remnant low by day 3. Rose continues to decelerate, now moving northwestward at about 9 kt. The depression should remain on a slow northwestward heading around the western portion of a subtropical ridge during the next 24 to 36 hours. After that time, the cyclone is forecast to turn northward, and then recurve northeastward ahead of a mid- to upper-level trough over the central Atlantic. The dynamical guidance envelope remained fairly steady this cycle and no significant change was made to the previous official forecast. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 22.9N 37.9W 30 KT 35 MPH 12H 22/1200Z 23.9N 38.9W 30 KT 35 MPH 24H 23/0000Z 25.0N 40.1W 30 KT 35 MPH 36H 23/1200Z 26.3N 41.0W 30 KT 35 MPH 48H 24/0000Z 27.6N 41.2W 30 KT 35 MPH 60H 24/1200Z 28.9N 40.0W 30 KT 35 MPH 72H 25/0000Z 29.7N 37.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 26/0000Z 31.3N 32.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 27/0000Z...DISSIPATED $$ Forecaster Brown