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Tropical Depression Fred Forecast Discussion Number 13
2021-08-12 22:54:03| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Thu Aug 12 2021 000 WTNT41 KNHC 122053 TCDAT1 Tropical Depression Fred Discussion Number 13 NWS National Hurricane Center Miami FL AL062021 500 PM EDT Thu Aug 12 2021 Fred remains poorly organized at this time. While the low-level circulation looks more closed than it did earlier, the center is broad and may have multiple vortices rotating around it. Also, while convection has increased from earlier today, there is only minimal convection near the center and little evidence of banding. The initial intensity remains 30 kt, with those winds likely occurring in squalls to the northeast of the center. Fred has slowed its forward speed, with the initial motion now 295/10. There is little change to the track forecast philosophy from the previous advisory. The subtropical ridge to the northeast should steer Fred west-northwestward for the first 24-36 h, followed by a turn toward the northwest as the cyclone approaches the western periphery of the ridge. By 96-120 h, a northward motion is expected as Fred moves into a weakness in the ridge. The track guidance has shifted westward since the previous advisory, most notably after about 24 h. Thus, that portion of the new forecast track has also been nudged a little westward, but it still lies to the east of the various consensus models. Fred remains in an environment of about 20 kt of westerly vertical wind shear. The shear is expected to persist during the next day or so, and this combined with the current disorganization of the system should prevent significant strengthening during that time. After that, there remains disagreement between the global models on the evolution of the upper-level trough over Florida and the upper-level anticyclone southeast of Fred. Some shear is likely to continue, but there may be a period of more conducive conditions from 36-72 h. The new intensity forecast is similar to the previous one in calling for slow strengthening through the first 36 h, with a little faster strengthening from 36-72 h. With that being said, the forecast 45-kt peak intensity is near the high end of the intensity guidance. KEY MESSAGES: 1. From Friday into Monday, heavy rainfall could lead to areal, urban, small stream, and exacerbated river flooding across southern and central Florida, and into the Big Bend of Florida. By early next week, heavy rain and flood impacts could extend into other portions of the Southeast and into the southern and central Appalachians and Piedmont. 2. Tropical storm conditions are possible beginning Friday night and Saturday in the Florida Keys and portions of southern Florida, where a Tropical Storm Watch is in effect. The risk of tropical storm conditions will spread northward along portions of the Florida west coast and to the Florida Panhandle Saturday night through Monday. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 21.3N 75.3W 30 KT 35 MPH 12H 13/0600Z 22.0N 77.0W 30 KT 35 MPH 24H 13/1800Z 23.0N 79.0W 30 KT 35 MPH 36H 14/0600Z 24.0N 80.6W 35 KT 40 MPH 48H 14/1800Z 25.2N 81.9W 35 KT 40 MPH 60H 15/0600Z 26.4N 83.1W 40 KT 45 MPH 72H 15/1800Z 28.1N 84.1W 45 KT 50 MPH 96H 16/1800Z 31.0N 85.5W 40 KT 45 MPH...INLAND 120H 17/1800Z 33.5N 85.5W 25 KT 30 MPH...INLAND $$ Forecaster Beven
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