Flhurricane.com - Central Florida Hurricane Center - Tracking Storms since 1995Hurricanes Without the Hype! Since 1995
The Atlantic is quiet
|
Show Selection: |
| #796336 (Received by flhurricane at: 4:35 PM 18.Aug.2015) TCDAT4 TROPICAL STORM DANNY DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 500 PM AST TUE AUG 18 2015 The convective cloud pattern of the tropical cyclone has continued to improve since the previous advisory, including the development of interlocking curved convective cloud bands and the formation of an upper-level anticyclonic outflow pattern. Passive microwave images indicate that the cyclone has a well-developed low- and mid-level structure. The intensity has been increased to 35 kt based on a Dvorak satellite intensity estimate of T2.5/35 kt from TAFB and a UW-CIMMS ADT estimate of T2.5/35 kt. As a result, the system has been upgraded to Tropical Storm Danny on this advisory. The initial motion estimate remains 280/11 kt. There is no significant change to the previous forecast track or reasoning. The global and regional models remain in good agreement on Danny moving west-northwestward toward a weakness in the subtropical ridge located along 45W longitude for the next 72 hours. After that time, however, there is some spread in the model guidance based on how much and how soon the ridge builds back in to the north of Danny. The UKMET retains the weakness in the ridge longer, taking the cyclone northeast of the Lesser Antilles. In contrast, the ECMWF model strengthens the ridge sooner, which drives Danny more westward and considerably faster at 96 and 120 hours. The GFS poorly initialized Danny this morning, and it is noticeably slower than all of the available model guidance and, therefore, has been given much less weight on this forecast cycle. The official forecast track is faster than the consensus model TVCN due to the much slower GFS model inducing a significant slow bias in the model consensus, and is roughly a blend of the ECMWF, HWRF, and GFS-Ensemble mean forecast solutions. Atmospheric and oceanic conditions surrounding Danny are expected to be favorable for slow but steady strengthening throughout the forecast period. The only inhibiting factor appears to be dry mid-level air located to the north and west of Danny occasionally getting entrained into the circulation. However, the low vertical wind shear regime that Danny will be migrating through should allow the convective structure of the cyclone to steadily increase in organization, which should enable the circulation to quickly mix out any dry air intrusions. The official intensity forecast is similar to but slightly lower than the intensity consensus model IVCN through 96 hours, and near the LGEM intensity model at 120 hours. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 10.9N 37.5W 35 KT 40 MPH 12H 19/0600Z 11.2N 38.9W 40 KT 45 MPH 24H 19/1800Z 11.6N 40.4W 45 KT 50 MPH 36H 20/0600Z 12.0N 41.7W 55 KT 65 MPH 48H 20/1800Z 12.5N 43.0W 65 KT 75 MPH 72H 21/1800Z 13.4N 46.0W 75 KT 85 MPH 96H 22/1800Z 13.9N 49.7W 85 KT 100 MPH 120H 23/1800Z 14.5N 54.6W 85 KT 100 MPH $$ Forecaster Stewart |
