000 WTNT44 KNHC 220238 TCDAT4 HURRICANE DANNY DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 PM AST FRI AUG 21 2015 After reaching its peak intensity earlier today, Danny appears to be starting a weakening trend. There has been no eye in infrared satellite imagery since about 1800 UTC, and a 2136 UTC WindSat pass showed that a narrow swath of drier air had worked its way into the inner core, eroding the southern eyewall. The shear analysis from CIMSS at the University of Wisconsin indicates that a little over 20 kt of southwesterly shear is now affecting Danny, and dropsonde data from a NOAA G-IV surveillance flight revealed that there was some light inflow into the western part of the circulation between 300 and 400 mb. Dvorak final-T numbers from TAFB and SAB were steady or decreased slightly from six hours ago; therefore, the initial intensity is lowered slightly to 95 kt. Vertical shear is expected to increase further during the next couple of days, which should allow drier air in the surrounding environment to penetrate into Danny's circulation. Therefore, there is no change in the thinking that Danny should weaken as it approaches and moves across the Leeward Islands and the Greater Antilles during the forecast period. The SHIPS diagnostics is currently showing only 10 kt of shear affecting Danny, and if the shear is actually higher as shown by the UW-CIMSS product, then the SHIPS and LGEM solutions probably keep Danny's intensity too high during the next few days. The global models continue to depict rapid weakening and show Danny degenerating into a surface trough in 3-4 days. As a compromise, the NHC intensity forecast is close to the IVCN intensity consensus and a little bit lower than the previous forecast. Danny is still expected to weaken to a tropical storm before it reaches the Leeward Islands between 48-72 hours. Danny's initial motion remains west-northwestward, or 295/9 kt. The hurricane is forecast to accelerate and turn westward during the next few days while the subtropical ridge builds westward over the southwestern Atlantic. The bulk of the track guidance is tightly clustered for the entire forecast period, and no appreciable changes to the previous NHC track forecast were required on this advisory cycle. NOAA and Air Force Reserve Unit reconnaissance aircraft are scheduled to investigate Danny and the surrounding environment Saturday afternoon. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 14.8N 49.8W 95 KT 110 MPH 12H 22/1200Z 15.1N 51.4W 85 KT 100 MPH 24H 23/0000Z 15.6N 53.8W 75 KT 85 MPH 36H 23/1200Z 16.0N 56.4W 65 KT 75 MPH 48H 24/0000Z 16.4N 59.0W 60 KT 70 MPH 72H 25/0000Z 17.6N 63.8W 55 KT 65 MPH 96H 26/0000Z 19.0N 68.5W 45 KT 50 MPH 120H 27/0000Z 20.0N 73.5W 30 KT 35 MPH $$ Forecaster Berg