|
Show Selection: |
| #1056547 (Received by flhurricane at: 11:02 AM 12.Aug.2021) TCDAT1 Tropical Depression Fred Discussion Number 12 NWS National Hurricane Center Miami FL AL062021 1100 AM EDT Thu Aug 12 2021 Fred is poorly organized this morning. Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft, along with 1-minute imagery from GOES-16, indicate that the circulation is barely closed. Dropsondes in the area reported surface pressures of 1013-1014 mb, and the maximum winds of near 30 kt are well to the northeast of the center. In addition, there is currently no organized convection anywhere near the center. Based on the evidence of the closed circulation, the system will be maintained as tropical depression for this advisory. However, the structure is currently closer to that of an open wave than a normal tropical cyclone. The initial motion is now 300/12. The subtropical ridge over the western Atlantic north of Fred should steer the cyclone west-northwestward during the next 36 h or so. This motion should take the depression away from the southeastern Bahamas and bring it near the north coast of Cuba. After that time, Fred should approach the western periphery of the ridge, which should cause the cyclone to turn northwestward and slow its forward speed. There remains some uncertainty as to the when and where of the turn, with the track guidance models remaining spread across a region from over Florida to the east-central Gulf of Mexico. The new track forecast is little changed from the previous NHC track, and it lies a little to the east of the consensus models for the first 72 h or so. Fred remains in an environment about 20 kt of westerly vertical wind shear. This shear is expected to persist during the next day or so, and this combined with the current disorganization should prevent significant strengthening during this time. While there is still disagreement between the global models on the forecast upper-level winds over the Gulf of Mexico, the shear could lessen after 36 h and allow some intensification as the cyclone nears south Florida and moves into the eastern Gulf. The intensity guidance has trended weaker since the last advisory, with none of the guidance currently calling for Fred to reach hurricane strength. The new intensity forecast is similar to the previous one while Fred is over water, and it follows the overall trend of the intensity guidance. KEY MESSAGES: 1. Heavy rainfall today could lead to flash, urban, and small stream flooding, along with possible rapid river rises and the potential for mudslides in the Dominican Republic and Haiti. 2. Tropical storm conditions are possible in the southeastern Bahamas and portions of Cuba today. 3. Beginning Friday, heavy rainfall could lead to areal, urban, and small stream flooding, along with possible rapid river rises across southern Florida. Heavy rainfall associated with Fred will impact the remainder of Florida and parts of the Southeast this weekend and into next week. 4. There is a risk of tropical storm conditions beginning early Saturday in the Florida Keys and south Florida. This risk will spread northward along portions of the Florida west coast and to the Florida Panhandle through Monday. A Tropical Storm Watch will likely be issued for portions of the Florida Keys and the southern Florida Peninsula this afternoon. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 20.9N 74.4W 30 KT 35 MPH 12H 13/0000Z 21.8N 76.2W 30 KT 35 MPH 24H 13/1200Z 22.8N 78.3W 30 KT 35 MPH 36H 14/0000Z 23.8N 79.9W 35 KT 40 MPH 48H 14/1200Z 24.8N 81.2W 35 KT 40 MPH 60H 15/0000Z 26.0N 82.4W 40 KT 45 MPH 72H 15/1200Z 27.5N 83.6W 45 KT 50 MPH 96H 16/1200Z 30.5N 85.0W 50 KT 60 MPH...INLAND 120H 17/1200Z 33.5N 85.0W 25 KT 30 MPH...INLAND $$ Forecaster Beven |