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Tropical Depression THIRTEEN-E
ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015 300 PM MDT WED AUG 26 2015 The area of low pressure located well to the southwest of the coast of Mexico has become sufficiently well organized to be classified as a tropical depression. Dvorak classifications were T2.0/30 kt from TAFB and T1.5/25 kt from SAB at 1800 UTC, and the initial intensity is therefore set at 25 kt. The environment ahead of the depression is characterized by low shear, very warm waters, and a moist atmosphere, so strengthening appears likely throughout the forecast period. In fact, some of the intensity models are quite aggressive. Both the SHIPS and LGEM models strengthen the cyclone to category 3 or 4 intensity in five days, and the GFS deepens the system to a central pressure that typically equates to a category 3 hurricane. Therefore, the official forecast shows steady intensification, with the cyclone reaching major hurricane strength by day 5. This forecast is slightly below the IVCN intensity consensus. The center has been somewhat difficult to locate, but the overall system has been moving quickly westward with a motion estimate of 280/17 kt. The depression is located to the south of a strong mid-level ridge located over northern Mexico and the adjacent Pacific waters. This ridge should continue steering the cyclone westward--with a gradual decrease in forward speed--through day 4. A breakdown of the ridge by day 5 could then support a west-northwestward motion at the end of the forecast period. The track guidance is in good agreement on this scenario, and the official forecast is relatively close the model consensus. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 10.8N 113.3W 25 KT 30 MPH 12H 27/0600Z 11.5N 115.5W 30 KT 35 MPH 24H 27/1800Z 12.0N 118.1W 35 KT 40 MPH 36H 28/0600Z 12.3N 120.3W 45 KT 50 MPH 48H 28/1800Z 12.4N 122.5W 55 KT 65 MPH 72H 29/1800Z 12.4N 126.5W 75 KT 85 MPH 96H 30/1800Z 13.0N 130.5W 95 KT 110 MPH 120H 31/1800Z 14.5N 134.0W 100 KT 115 MPH $$ Forecaster Berg NNNN