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Tropical Depression Twenty-one-E Forecast Discussion Number 3
2020-11-18 09:36:41| National Hurricane Center (East Pacific)
Issued at 100 AM PST Wed Nov 18 2020 000 WTPZ41 KNHC 180836 TCDEP1 Tropical Depression Twenty-One-E Discussion Number 3 NWS National Hurricane Center Miami FL EP212020 100 AM PST Wed Nov 18 2020 The curved band feature that was prominent in earlier satellite images has dissipated, likely due to very dry air surrounding the cyclone. The depression now consists of a small central dense overcast (CDO) that has just recently become established in the past few hours. Earlier ASCAT data indicated that the strongest winds were occurring to the west of the center of the depression, near the curved band that existed at that time, while winds of 20-25 kt were occurring around the center. The nearest sampling by a scatterometer tonight was by the ASCAT-A, which did pass over some of the same area that had the strongest winds earlier, with peak winds now only 20 kt. Assuming the reorganizing of the convection near the center has helped to increased the winds somewhat there, the initial intensity is being held at 30 kt. If the current CDO feature persists this morning, then the depression will likely strengthen to a tropical storm later today. By early Thursday, moderate west-southwesterly shear, cooler oceanic temperatures, and the presence of a very dry and stable air mass should cause the cyclone to begin weakening, and by Thursday night the system is expected to degenerate to a remnant low. The latest NHC intensity forecast is unchanged from the previous one and is in agreement with the various multimodel consensus aids. The initial motion continues to be west-northwestward at 10 kt. The depression is moving to the south of a mid-level ridge, and the cyclone is expected to continue in this general motion through tonight. A turn to the west within the low-level easterly trade wind flow is expected on Thursday as the system loses its deep convection and becomes shallow. The track forecast was nudged a little to the left of the previous advisory track due to a shift in the model guidance in that direction. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 15.7N 115.2W 30 KT 35 MPH 12H 18/1800Z 16.1N 116.8W 35 KT 40 MPH 24H 19/0600Z 16.5N 118.9W 35 KT 40 MPH 36H 19/1800Z 16.7N 120.9W 30 KT 35 MPH 48H 20/0600Z 16.8N 123.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 20/1800Z 16.8N 125.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 21/0600Z...DISSIPATED $$ Forecaster Latto
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