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#1057149 (Received by flhurricane at: 4:54 AM 16.Aug.2021)
TCDAT1

Tropical Storm Fred Discussion Number 27
NWS National Hurricane Center Miami FL AL062021
400 AM CDT Mon Aug 16 2021

Earlier reconnaissance aircraft data and satellite imagery indicated
that Fred`s low-level circulation center briefly emerged out from
underneath the southwestern edge of the convective cloud shield
between 0200-0400 UTC. The circulation center, however, has recently
moved back underneath the edge of the main region of convection,
with a new bust of thunderstorms having developed over or near the
low-level center. Having said that, Fred still remains a sheared
tropical cyclone, with Tallahassee NOAA Doppler radar data
indicating that the upper-level circulation at around 30,000 ft is
tilted about 40 nmi northeast of the low-level center. The last
reports from the Air Force Reserve reconnaissance aircraft indicated
that the central pressure had risen from 999 mb to 1004 mb during
the time the low-level center was fully exposed southwest of the
deep convection. However, the pressure has likely fallen again now
the center is back underneath the convection. An intensity of 45 kt
is being maintained for this advisory based on the last reliable
reconnaissance SFMR data of about 45 kt, which corresponds well with
a T3.0/45 kt Dvorak satellite shear-pattern intensity estimate.

Fred is moving northward now, or 355/08 kt. The latest NHC model
guidance remains in excellent agreement that Fred will continue
moving in a general northward motion today as the cyclone moves
through a break in the subtropical ridge that is oriented
east-to-west across northern Florida. Landfall is expected in the
western Florida Panhandle region by late afternoon or evening today.
The track guidance has shifted slightly to the east of the previous
advisory track, and the new official forecast track has been nudged
in that direction, but not as far east as the tightly packed
consensus models owing to the strength of the ridge noted in 16/0000
UTC upper-air data.

Fred is forecast to remain in moderate vertical wind shear
conditions throughout the 48-h forecast period. However, the shear
vector is expected to gradually back around from the current
southwesterly direction to more of a south-southwesterly component
right up until landfall occurs, which will align more with Fred`s
track direction. This reduction in the effective shear across the
cyclone should allow for some additional strengthening until
landfall occurs, with the distinct possibility that Fred could reach
a peak intensity of 55 kt in 18 hours. After landfall, the
combination of land interaction and the vertical shear increasing to
more than 20 kt should result in rapid weakening, with Fred forecast
to dissipate by 60 hours over the southern Appalachian Mountains.
The official intensity forecast closely follows a blend of the HCCA
and IVCN intensity consensus models.

Users are reminded not to focus on the exact forecast track of
Fred, since rainfall, storm surge, and wind hazards will extend
over an area well east of the center.

KEY MESSAGES:

1. Through Tuesday, heavy rainfall may lead to flash, urban, small
stream, and isolated river flooding impacts across the Southeast.
By the middle of the week as Fred lifts northward and inland, heavy
rainfall and flooding will impact the southern and central
Appalachians, the Piedmont of the Southeast, and the Mid-Atlantic.

2. Dangerous storm surge inundation is possible along portions of
the coast of the Florida Panhandle and the Florida Big Bend region,
and a Storm Surge Warning is in effect for this area. Interests in
these areas should follow any advice given by local officials.

3. Tropical storm conditions are expected in the Tropical Storm
Warning area in the Florida Panhandle beginning on Monday.


FORECAST POSITIONS AND MAX WINDS

INIT 16/0900Z 27.9N 86.0W 45 KT 50 MPH
12H 16/1800Z 29.1N 86.1W 50 KT 60 MPH
24H 17/0600Z 31.0N 85.7W 40 KT 45 MPH...INLAND
36H 17/1800Z 33.1N 85.2W 25 KT 30 MPH...INLAND
48H 18/0600Z 35.6N 84.2W 20 KT 25 MPH...POST-TROP/INLAND
60H 18/1800Z...DISSIPATED

$$
Forecaster Stewart