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Tropical Depression Fred Forecast Discussion Number 11
2021-08-12 10:35:40| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Thu Aug 12 2021 763 WTNT41 KNHC 120835 TCDAT1 Tropical Depression Fred Discussion Number 11 NWS National Hurricane Center Miami FL AL062021 500 AM EDT Thu Aug 12 2021 The rugged terrain of Hispaniola has taken a toll on Fred. Satellite images and surface observations indicate that the circulation is stretched out and seems to resemble a trough at the surface. The system is now emerging back over water and is located between Haiti, eastern Cuba, and the southeastern Bahamas. Most of the associated showers and thunderstorms are located to the east of the estimated center, with heavy rains continuing over portions of Hispaniola. The initial intensity is estimated to be 30 kt, but there is limited data to confirm this. Both the NOAA and Air Force Hurricane Hunters will be investigating Fred later this morning, and the data from both planes will be helpful in estimating Fred's strength and structure. Fred appears to be moving west-northwestward at about 14 kt. The track forecast reasoning has not changed much. A subtropical ridge currently situated to the north of Fred over the western Atlantic should continue to steer the system west-northwestward for the next 36 to 48 hours. This motion should take the storm just north of or across Cuba and the southeastern Bahamas during that time period. By the weekend, the models suggest that Fred will be rounding the western periphery of the ridge, which will likely a cause a slow down and a gradual turn to the northwest and then the north across portions of the Florida Keys, the Florida peninsula, and the eastern Gulf of Mexico. There is uncertainty in exactly where and when Fred will make that turn to the right, with models currently spanning a region from over Florida to the east-central Gulf of Mexico. The NHC track forecast remains on the right side of the guidance envelope, near the typically more skillful global models and consensus aids. Fred is currently in an environment of about 20 kt of westerly vertical wind shear. This shear is expected to persist during the next day or so, and those unfavorable winds combined with some land interaction with Cuba should prevent the system from strengthening much, if at all, during that time period. The shear could lessen on Friday and since SSTs are very warm and there is abundant environmental moisture, some strengthening seems likely when Fred is approaching the Florida Keys and south Florida Friday night and Saturday. After that time, the intensity forecast becomes more complicated by how much land interaction there will be with Florida. Since the official forecast shows a track over the eastern Gulf, additional strengthening is predicted before Fred makes its final landfall along the Florida Big Bend region or Florida panhandle late in the weekend or early next week. However, that part of the intensity forecast, since it will be very track dependent, is more uncertain. KEY MESSAGES: 1. Continued heavy rainfall today could lead to flash, urban, and small stream flooding, along with possible rapid river rises and potential mudslides in the Dominican Republic and Haiti. 2. Tropical storm conditions are possible in northern Haiti and the southeastern Bahamas this morning, and in portions of Cuba later today. 3. Beginning Friday, heavy rainfall could lead to areal, urban, and small stream flooding, and 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. These conditions are expected to spread northward along portions of the Florida west coast and the Florida Panhandle through Monday. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 20.2N 73.5W 30 KT 35 MPH 12H 12/1800Z 21.0N 75.1W 30 KT 35 MPH 24H 13/0600Z 22.0N 77.2W 30 KT 35 MPH 36H 13/1800Z 23.0N 79.1W 35 KT 40 MPH 48H 14/0600Z 23.8N 80.3W 35 KT 40 MPH 60H 14/1800Z 25.1N 81.4W 40 KT 45 MPH 72H 15/0600Z 26.6N 82.6W 45 KT 50 MPH 96H 16/0600Z 29.5N 84.4W 50 KT 60 MPH 120H 17/0600Z 32.2N 84.7W 35 KT 40 MPH...INLAND $$ Forecaster Cangialosi
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