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| #797627 (Received by flhurricane at: 10:38 AM 23.Aug.2015) TCDAT4 TROPICAL STORM DANNY DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 AM AST SUN AUG 23 2015 Danny appears to be maintaining its intensity for now. The low-level center is estimated to be near the southwestern edge of the main mass of deep convection, and considerable lightning activity has recently been occurring near the center. The current intensity estimate is held at 45 kt in agreement with the latest Dvorak estimates and earlier Hurricane Hunter aircraft data. The center of the storm should pass very near, or over, the French data buoy 41300 shortly, and this should provide additional information about the intensity. Southwesterly vertical shear of nearly 20 kt along with dry mid-level air should continue to affect Danny over the next couple of days. Both the GFS and ECMWF global models continue to depict the system opening up into a wave within 48 hours. Given these unfavorable signs, the official forecast shows weakening as in the previous advisories. However, because of the uncertainties in tropical cyclone intensity prediction, it is prudent to issue a tropical storm watch for Puerto Rico and the U.S. Virgin Islands at this time. Danny continues westward, or 275/13 kt. A westward to west- northwestward track is expected over the next few days as the cyclone moves on the southern side of a low- to mid-level ridge. The track model guidance has shifted a little south on this cycle, and so has the official forecast. This is close to the latest dynamical model consensus. If Danny weakens faster than expected, it could move even farther south of this track. The system could bring much-needed rainfall to Puerto Rico over the next few days. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 15.8N 57.3W 45 KT 50 MPH 12H 24/0000Z 16.0N 59.3W 40 KT 45 MPH 24H 24/1200Z 16.5N 61.9W 35 KT 40 MPH 36H 25/0000Z 17.0N 64.5W 30 KT 35 MPH 48H 25/1200Z 17.5N 67.1W 30 KT 35 MPH 72H 26/1200Z 19.2N 72.0W 25 KT 30 MPH...INLAND 96H 27/1200Z 21.0N 76.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 28/1200Z...DISSIPATED $$ Forecaster Pasch |
