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Tropical Depression Seven Forecast Discussion Number 1
2020-07-21 22:36:48| National Hurricane Center (Atlantic)
Issued at 500 PM AST Tue Jul 21 2020 000 WTNT42 KNHC 212036 TCDAT2 Tropical Depression Seven Discussion Number 1 NWS National Hurricane Center Miami FL AL072020 500 PM AST Tue Jul 21 2020 Satellite imagery and scatterometer data indicate that the low pressure area located over the central tropical Atlantic has a well-defined circulation and sufficient organized convection to be designated a tropical depression. Thus, advisories are being initiated on Tropical Depression Seven. The initial intensity is set at 30 kt in best agreement with the subjective satellite intensity estimate from TAFB. The initial motion is 300/7. The depression is south of a strong subtropical ridge over the central Atlantic, and over the next several days it should turn generally westward and accelerate as it encounters the easterly flow associated with the ridge. The ECMWF, GFS, and UKMET models are in reasonably good agreement on their track forecasts, and the NHC official forecast is close to them and the various consensus models. The intensity forecast is lower confidence. The GFS, ECMWF, and UKMET models forecast the cyclone to be dissipated or be a weak low by the 120 h point, likely due to to some vertical shear and dry air entrainment. On the other hand, the SHIPS-based guidance and the HWRF forecast the system to be a hurricane at 120 h, shrugging off the shear and dry air. The NHC intensity forecast will be a compromise between these extremes, showing a peak intensity of 55 kt in 60-72 h followed by some weakening based on the global models. The cyclone is small in size, and as a result it could change intensity - both up and down - faster than what is currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 9.8N 40.4W 30 KT 35 MPH 12H 22/0600Z 10.1N 41.7W 35 KT 40 MPH 24H 22/1800Z 10.3N 43.9W 40 KT 45 MPH 36H 23/0600Z 10.3N 46.3W 45 KT 50 MPH 48H 23/1800Z 10.4N 49.0W 50 KT 60 MPH 60H 24/0600Z 10.6N 51.6W 55 KT 65 MPH 72H 24/1800Z 11.0N 54.7W 55 KT 65 MPH 96H 25/1800Z 12.0N 61.0W 50 KT 60 MPH 120H 26/1800Z 13.5N 68.5W 45 KT 50 MPH $$ Forecaster Beven
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