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| #797172 (Received by flhurricane at: 4:45 PM 21.Aug.2015) TCDAT4 HURRICANE DANNY DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 500 PM AST FRI AUG 21 2015 A NOAA Hurricane Hunter aircraft investigated Danny around 1600-1730 UTC. It found winds as high as 111 kt at the 12,000 ft flight level and surface wind estimates from the Stepped Frequency Microwave Radiometer as high as 104 kt. It also reported a dropsonde central pressure of 974 mb. Based on these data, Danny reached a 100-kt intensity at that time. Since then, the eye has disappeared in satellite imagery, and the cyclone is showing signs of being affected by southwesterly vertical wind shear. The initial intensity is 100 kt for this advisory based on an expected lag between the decay of the cloud pattern and the cyclone's weakening. That being said, this intensity could be generous. The initial motion is now 295/9. The subtropical ridge north of Danny remains weaker than normal due to a deep-layer trough over the western Atlantic. This trough is expected to lift northward during the next couple of days, allowing the ridge to build westward and strengthen. This evolution should cause Danny to turn more westward with some increase in forward speed. The track guidance is in good agreement with this scenario and forecasts Danny to be near the Leeward Islands in about 72 hours, near Puerto Rico and the Virgin Islands in about 84-96 hours, and in the vicinity of Hispaniola by day 5. The new forecast track has a noise-level nudge to the north of the previous forecast and is in best agreement with the GFS and ECMWF models. It lies just south of the center of the guidance envelope. Danny has likely peaked in intensity based on the signs of shear in the cloud pattern, stronger upper-level winds present west of the cyclone, and abundant nearby dry air. Although it starts from a higher initial intensity than the previous forecast, the new intensity forecast still calls for Danny to weaken below hurricane strength at about 48 hours. After that, the system should continue to weaken as it moves near or over the Greater Antilles in close proximity to an upper-level trough. The GFS/ECWMF/UKMET models all forecast Danny to degenerate to a tropical wave by 120 hours, so the new intensity forecast compromises between this extreme and the SHIPS/LGEM models, which forecast a stronger cyclone at that time. NOAA and Air Force Reserve Unit reconnaissance aircraft will investigate Danny again Saturday afternoon. These data will provide a better assessment of the intensity and structure of the hurricane. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 14.5N 49.1W 100 KT 115 MPH 12H 22/0600Z 15.0N 50.5W 95 KT 110 MPH 24H 22/1800Z 15.5N 52.7W 85 KT 100 MPH 36H 23/0600Z 15.9N 55.2W 70 KT 80 MPH 48H 23/1800Z 16.3N 57.8W 60 KT 70 MPH 72H 24/1800Z 17.5N 62.5W 55 KT 65 MPH 96H 25/1800Z 18.5N 67.0W 50 KT 60 MPH 120H 26/1800Z 19.5N 71.5W 35 KT 40 MPH...INLAND $$ Forecaster Beven |
