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Tropical Depression Seventeen Forecast Discussion Number 2
2020-09-07 10:37:11| National Hurricane Center (Atlantic)
Issued at 500 AM AST Mon Sep 07 2020 000 WTNT42 KNHC 070837 TCDAT2 Tropical Depression Seventeen Discussion Number 2 NWS National Hurricane Center Miami FL AL172020 500 AM AST Mon Sep 07 2020 Tropical Depression Seventeen is a large tropical cyclone, with its circulation evident several hundred miles from its center. An area of deep convection has developed tonight just over and to the east of its center with cloud top temperatures as low as -80 degrees C. However, there appears to be some dry air in the northwestern portion of the cyclone's circulation limiting convection there. The latest Dvorak satellite intensity estimates from TAFB and UW-CIMSS support keeping the initial intensity at 30 kt. The depression has been moving west-northwestward at about 5 kt over the past 12 hours. This general motion is expected to continue throughout the 5-day forecast period, with some increase in forward speed over the next couple of days as the cyclone is steered by a weak mid-level ridge to its north. The overall guidance shifted slightly to the north through day 3 and the latest NHC forecast lies in between the previous one and the consensus track guidance through this time period. For days 3 through 5, the forecast track is little changed from the previous one and is in good agreement with the fairly tightly clustered track guidance. Other than some dry air in the vicinity of the depression, the overall environment looks favorable for strengthening over the next few days. However, due to the large size of the circulation, strengthening may occur more slowly than what might be expected from a more compact cyclone. Therefore, only gradual strengthening is indicated in the official forecast during that time. By 72 h, increasing vertical wind shear should limit further intensification, and may cause some weakening to occur. The latest NHC intensity forecast is a blend of the previous one and the HFIP corrected consensus, HCCA. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 17.3N 42.1W 30 KT 35 MPH 12H 07/1800Z 17.5N 42.6W 35 KT 40 MPH 24H 08/0600Z 17.8N 43.2W 35 KT 40 MPH 36H 08/1800Z 18.3N 44.1W 40 KT 45 MPH 48H 09/0600Z 19.1N 45.6W 45 KT 50 MPH 60H 09/1800Z 19.7N 47.1W 50 KT 60 MPH 72H 10/0600Z 20.1N 49.0W 50 KT 60 MPH 96H 11/0600Z 20.6N 52.7W 45 KT 50 MPH 120H 12/0600Z 21.7N 55.5W 45 KT 50 MPH $$ Forecaster Latto
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