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#872717 (Received by flhurricane at: 4:38 PM 22.Aug.2016) TCDAT2 TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 PM AST MON AUG 22 2016 The low pressure area located west-southwest of the Cabo Verde Islands has developed a well-defined circulation and sufficient organized convection to be considered a tropical depression. Microwave imagery suggests that the system is likely still consolidating, with two or more vorticity centers rotating around a mean center. The initial intensity is set to 30 kt in agreement with a satellite intensity estimate from TAFB. The initial motion is 275/16. The cyclone is on the south side of a deep-layer ridge over the eastern Atlantic, and as a result it should move generally west-northwestward for the next 36-48 hours. Beyond that time, the cyclone is forecast to turn northwestward toward a weakness in the ridge over the central Atlantic. The track guidance is in good agreement with this scenario, and the forecast track lies near the consensus models. The depression is currently in an environment of light to moderate easterly vertical shear. This, combined with warm sea surface temperatures, should allow strengthening. One possible negative factor, however, is a tongue of African dust/dry air wrapping around the west side of the circulation. On that basis that the dry air will not stop development, the intensity forecast calls for steady strengthening through 72 hours. After that time, arrested development is likely due to the cyclone encountering moderate to strong westerly vertical shear. FORECAST POSITIONS AND MAX WINDS INIT 22/2100Z 12.1N 29.0W 30 KT 35 MPH 12H 23/0600Z 12.4N 31.4W 40 KT 45 MPH 24H 23/1800Z 13.2N 34.4W 50 KT 60 MPH 36H 24/0600Z 14.5N 37.2W 60 KT 70 MPH 48H 24/1800Z 16.2N 39.9W 70 KT 80 MPH 72H 25/1800Z 19.7N 44.8W 80 KT 90 MPH 96H 26/1800Z 23.8N 50.1W 75 KT 85 MPH 120H 27/1800Z 26.8N 54.0W 75 KT 85 MPH $$ Forecaster Beven/Roberts |