ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE DANNY DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 AM AST SAT AUG 22 2015 Danny's cloud pattern is similar to that of six hours ago, with a central dense overcast and some outer banding in the northeastern semicircle. However, the size of the overcast has diminished with the center getting closer to the edge. The initial intensity is decreased to 80 kt based on decreasing satellite intensity estimates and continuity from the previous advisory. However, this could be generous. NOAA and Air Force Reserve Unit reconnaissance aircraft are scheduled to investigate Danny this afternoon and should provide a better estimate of its intensity. The initial motion is now 285/10. There is no change in the forecast philosophy from the previous advisory, with Danny expected to turn westward and accelerate later today as the subtropical ridge to the north of the cyclone builds westward and strengthens. This general motion is expected to persist for the next several days taking Danny across the Leeward Islands in about two days, and near Puerto Rico and Hispaniola in 3 to 4 days. The track model guidance remains in good agreement with this, and the forecast track lies near the center of the track guidance envelope. Danny is expected to move through a dry and stable air mass and encounter moderate to strong southwesterly vertical wind shear for at least the next three days. This should cause continued weakening, and the cyclone is forecast to be a tropical storm as it moves over or near the northeastern Caribbean Islands. The intensity forecast becomes lower confidence at days 4 and 5 due to the uncertainty in how much land Danny will encounter, disagreements between the dynamical models over the forecast shear, and continued divergence between the models forecasting Danny to dissipate and the models forecasting it to survive. The latter part of the forecast compromises between these extremes by showing a continued weakening trend. A tropical storm watch is being issued for portions of the Leeward Islands at this time. Additional watches or warning may be necessary for this area, as well as the Virgin Islands and Puerto Rico, later today or tonight. FORECAST POSITIONS AND MAX WINDS INIT 22/1500Z 15.4N 52.0W 80 KT 90 MPH 12H 23/0000Z 15.7N 53.7W 70 KT 80 MPH 24H 23/1200Z 16.1N 56.1W 60 KT 70 MPH 36H 24/0000Z 16.6N 58.7W 55 KT 65 MPH 48H 24/1200Z 17.2N 61.3W 50 KT 60 MPH 72H 25/1200Z 18.5N 66.0W 45 KT 50 MPH 96H 26/1200Z 20.5N 71.0W 40 KT 45 MPH 120H 27/1200Z 22.0N 75.5W 30 KT 35 MPH $$ Forecaster Beven NNNN