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Tropical Depression Six-E Forecast Discussion Number 1
2020-07-13 22:34:48| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Mon Jul 13 2020 719 WTPZ41 KNHC 132034 TCDEP1 Tropical Depression Six-E Discussion Number 1 NWS National Hurricane Center Miami FL EP062020 300 PM MDT Mon Jul 13 2020 The small disturbance and intermittent low pressure system that the NHC has been tracking for the past few days has finally developed a well-defined, closed surface circulation based on 1639Z ASCAT-B surface wind vector ambiguity data, and the system is thus being classified as Tropical Depression Six-E. Deep convection developed overnight and this morning, which helped to spin up a low-level center near and just inside of the northeastern portion of the convective cloud canopy. In addition, the forward speed has also decreased from 20 kt down to 14 kt, which has also likely helped to close off the circulation on the south side. The ASCAT scatterometer wind data data supported an intensity of at least 30 kt, and this is consistent with 18Z Dvorak satellite classifications of T2.0/30 kt from both TAFB and SAB. The initial motion estimate is 270/14 kt based on conventional, microwave, and scatterometer satellite fix data over the past 12 hours. The small cyclone is expected to be steered generally westward at about the same forward speed for the next few days due to a strong subtropical ridge situated to the north of the depression. By 96 h, the system is forecast to degenerate into an open wave. The NHC official forecast track lies close to the tightly packed simple consensus models, which is a just a little south of the NOAA corrected-consensus model, HCCA. The current northerly vertical wind shear of about 15 kt affecting the depression is forecast to decrease to below 10 kt in 12-18 hours, and remain that way until the 48-h period. This should allow for some slight strengthening to occur during the next 36 hours or so. By 48 hours and beyond, the cyclone will be moving over sub-26 deg C sea-surface temperatures and the shear is forecast to become westerly to northwesterly at near 20 kt. The combination of these two negative factors should induce significant weakening of the small tropical cyclone, resulting in degeneration to a remnant low by 72 h and dissipation by 96 hours. The official intensity forecast closely follows the IVCN intensity consensus model. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 16.6N 112.6W 30 KT 35 MPH 12H 14/0600Z 16.7N 114.9W 35 KT 40 MPH 24H 14/1800Z 16.8N 117.8W 35 KT 40 MPH 36H 15/0600Z 16.8N 120.6W 35 KT 40 MPH 48H 15/1800Z 16.8N 124.2W 30 KT 35 MPH 60H 16/0600Z 16.6N 127.9W 30 KT 35 MPH 72H 16/1800Z 16.5N 131.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 17/1800Z...DISSIPATED $$ Forecaster Stewart
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