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Tropical Depression Twenty-one-E Forecast Discussion Number 1
2019-11-16 09:50:03| National Hurricane Center (East Pacific)
Issued at 400 AM CDT Sat Nov 16 2019 000 WTPZ41 KNHC 160849 TCDEP1 Tropical Depression Twenty-One-E Discussion Number 1 NWS National Hurricane Center Miami FL EP212019 400 AM CDT Sat Nov 16 2019 Deep convection associated with the small low pressure area located well south of the coast of Mexico has continued to increase and become better organized overnight. ASCAT data from 03-04Z indicated that the circulation was well-defined and there were believable 30 kt wind vectors. The ASCAT revealed a few higher wind vectors, but they may have been rain contaminated. Based on these data and a Dvorak T-number of 2.0 from TAFB, advisories are being initiated on a 30-kt tropical depression. The intensity forecast for this system is a bit tricky as small systems such as this can spin up or down quite quickly. In the short-term, a dry and more stable air from a Gulf of Tehuantepec gap wind event could be entrained into the northern portion of the circulation today, which could cause a disruption in the deep convection and/or an elongation of the circulation. However, if the small cyclone remains south of the main area of Tehuantepec winds, low vertical wind shear conditions favor some intensification. The NHC intensity forecast leans on the latter scenario and call for some strengthening during the next 24 hours or so. After that time, increasing southerly shear is expected to cause weakening, and the system is forecast to degenerate into a remnant low in 3 to 4 days. The intensity is more uncertain than normal, but is fairly close to the intensity consensus aids. The depression is moving westward or 270/10 kt. The track forecast is a bit more straightforward as the cyclone should be steered generally westward to the south of a mid-level ridge located over southern Mexico during the next couple of days. After that time, the cyclone is forecast to near the southwestern portion of the ridge and a west-northwestward heading is predicted. The global models are in fairly good agreement on this scenario and the NHC track follows a blend of the various global model predictions. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 9.2N 99.2W 30 KT 35 MPH 12H 16/1800Z 9.0N 100.8W 35 KT 40 MPH 24H 17/0600Z 8.9N 102.1W 40 KT 45 MPH 36H 17/1800Z 9.0N 103.1W 40 KT 45 MPH 48H 18/0600Z 9.4N 104.0W 35 KT 40 MPH 72H 19/0600Z 10.1N 106.9W 30 KT 35 MPH 96H 20/0600Z 10.5N 109.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/0600Z...DISSIPATED $$ Forecaster Brown
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