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#796994 (Received by flhurricane at: 10:38 PM 20.Aug.2015) TCDAT4 HURRICANE DANNY DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 PM AST THU AUG 20 2015 Danny continues to produce a compact central dense overcast, and cloud tops are a little colder than earlier due to a recent burst of convection in the eyewall. Coincidentally, the convective canopy has intermittently been obscuring the tiny eye that was observed earlier today. The initial intensity remains 70 kt based on a blend of subjective Dvorak satellite estimates of T4.0/65 kt from TAFB and T4.5/77 kt from SAB. The hurricane continues to move west-northwestward, or 295/9 kt, toward a break in the subtropical ridge located northeast of the Leeward Islands. The track guidance shows this motion continuing for another 36 hours, with Danny then turning westward and accelerating from 48 hours through day 5 while the ridge builds westward north of the Greater Antilles. With the exception of the GFDL, GFDN, and NAVGEM--which insist that Danny will turn northwestward before reaching the Leeward Islands--the other track models are in agreement on a future track near or just south of the northern Leeward Islands and Greater Antilles. This clustering of the guidance required no significant changes to the official NHC track forecast on this advisory cycle. As has been mentioned in earlier discussions, Danny is susceptible to sudden and possibly unexpected changes in intensity due to its small size. Since vertical shear is expected to remain low for another 24 hours or so, Danny could certainly strengthen some more if it can avoid intrusions of dry air into the inner core. After 36 hours, an increase in westerly to southwesterly shear and a decrease in mid-level relative humidities are expected to lead to weakening, and Danny is forecast to weaken to a tropical storm before it reaches the Leeward Islands. The updated NHC intensity forecast is very similar to the previous one and remains close to the IVCN consensus. It should be noted that given Danny's small size, the weakening rate after 36 hours could be faster than indicated in the official forecast. A NOAA aircraft will be conducting a research mission in and around Danny Friday afternoon, and an Air Force Reserve Unit reconnaissance aircraft will investigate Danny Saturday afternoon. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 13.4N 46.6W 70 KT 80 MPH 12H 21/1200Z 14.0N 47.9W 75 KT 85 MPH 24H 22/0000Z 14.7N 49.8W 75 KT 85 MPH 36H 22/1200Z 15.2N 51.9W 70 KT 80 MPH 48H 23/0000Z 15.6N 54.2W 60 KT 70 MPH 72H 24/0000Z 16.5N 59.3W 55 KT 65 MPH 96H 25/0000Z 17.5N 64.5W 50 KT 60 MPH 120H 26/0000Z 18.0N 69.5W 45 KT 50 MPH $$ Forecaster Berg |