Atlantic Basin Tropical Cyclones

Tropical Depression Rose Forecast Discussion


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




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