ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Tropical Depression Eighteen-E Discussion Number 12 NWS National Hurricane Center Miami FL EP182021 300 AM CST Sun Nov 07 2021 The disheveled convective appearance of the depression has not changed much since the previous advisory. However, recent ASCAT scatterometer surface wind data indicate that the wind field has actually become a little better defined. The ASCAT data also indicated a small patch of wind speeds of 27-28 kt north of the center, so the intensity remains at 30 kt for this advisory, which is consistent with the latest subjective and objective satellite intensity estimates. The depression is moving due west now, or 270/12 kt. The small cyclone is forecast to move westward to west-northwestward along the southern periphery of a deep-layer subtropical ridge for the next 5 days. This stable synoptic flow pattern has resulted in little change to the previous forecast track, and the new NHC advisory track lies along or just south of the middle of the consensus track model envelope. Although the associated convection remains poorly organized, the improved low-level wind field noted in the aforementioned ASCAT data wouldn't require much more convective organization for the cyclone to reach tropical storm status at any time during the next 60 h or so while the vertical wind shear remains low at only around 5 kt. By 72 h, however, the shear is forecast to increase from the southwest and west at 20-25 kt while the cyclone moves westward into a progressively drier airmass. That negative combination is expected to induce weakening by 96 h, with the system degenerating into a remnant low by 120 h, if not sooner. The new NHC intensity forecast is just an update of the previous advisory, and closely follows a blend of the the GFS and ECMWF models intensity forecasts, which show a lower intensity on days 4 and 5 as compared to the higher HWRF-/HMON-based consensus intensity models. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 8.2N 100.5W 30 KT 35 MPH 12H 07/1800Z 8.5N 102.3W 30 KT 35 MPH 24H 08/0600Z 8.9N 104.6W 30 KT 35 MPH 36H 08/1800Z 9.3N 107.1W 35 KT 40 MPH 48H 09/0600Z 9.7N 109.6W 35 KT 40 MPH 60H 09/1800Z 10.1N 111.9W 35 KT 40 MPH 72H 10/0600Z 10.2N 114.5W 35 KT 40 MPH 96H 11/0600Z 10.4N 119.0W 30 KT 35 MPH 120H 12/0600Z 10.4N 123.6W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart NNNN
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