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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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