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Tropical Depression Claudette Discussion Number  10
NWS National Hurricane Center Miami FL       AL032021
1000 PM CDT Sat Jun 19 2021

Although the center is well inland, Claudette has become better 
organized during the past several hours, with a large area of 
convection forming close to the center in the northern quadrant.  
In addition to this convection, a large area of rain bands is 
present over the eastern semicircle from the northeastern Gulf of 
Mexico northward into southeastern Tennessee   Surface observation 
indicate that the maximum winds have decreased a little more and 
are now 25 kt, with these winds mainly over the Gulf of Mexico to 
the south of the center.  Surface observations also indicate that 
the central pressure is 1005-1006 mb.  

The initial motion is still northeastward, but is a little slower 
than before, 050/12 kt.  A turn to the east-northeast is expected
during the next 6-12 h as Claudette moves in the westerlies on the
north side of the subtropical ridge.  This motion should take the
system across portions of the southeast U.S. during the next 36 h 
or so and then over the western Atlantic and toward Atlantic
Canada with a significant increase in forward speed between 36-   
72 h.  The track forecast guidance remains tightly clustered and 
has changed little since the last advisory.  So, the new forecast 
track is basically an update of the previous forecast, and it calls 
for the system to be near the coast of North Carolina at about the 
36 h point.

The intensity guidance continues to show a sizable amount of 
spread.  On one side, the GFS has an ill-defined system reaching 
the Carolina coast in 36 h, with only minimal subsequent 
intensification after Claudette moves into the Atlantic.  On the 
other side, the UKMET shows the central pressure falling below 1000 
mb before the system reaches the Atlantic and winds exceeding 50 kt 
once the system is over water.  The ECMWF and Canadian models lie 
between these extremes.  The model forecasts do not show any strong 
baroclinic forcing that would lead to the level of intensification 
shown by the UKMET.  On the other hand, the short-term trends in 
the cyclone's organization currently favor the stronger model 
forecasts.  Given the uncertainty, the intensity forecast is not 
changed much from the previous forecast, except for moving the time 
of dissipation up by 24 h as Claudette gets absorbed into a large 
extratropical low over eastern Canada.  If the current trends 
continue, or later GFS runs forecast a stronger system, the 
intensity forecast could be adjusted upward in later advisories.

It should be noted that even the weaker GFS solution brings 30-35 
kt winds to the North Carolina coast near the 36 h point, and a 
tropical storm warning will likely be required for a portion of the 
current watch area on the next advisory.

Key Messages:
 
1. Claudette is expected to produce heavy rainfall and flash 
flooding across portions of the Florida Panhandle, northern Alabama, 
and Georgia through tonight, and into the Carolinas on Sunday. 
Considerable flash, urban, and small stream flooding impacts are 
possible across these areas. 
 
2. Tropical storm conditions are possible along portions of the
North Carolina coast Sunday night and Monday, where a Tropical Storm
Watch is in effect.  Tropical Storm Warnings will likely be 
required for portions of this area early Sunday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0300Z 32.6N  87.0W   25 KT  30 MPH...INLAND
 12H  20/1200Z 33.3N  84.7W   25 KT  30 MPH...INLAND
 24H  21/0000Z 34.2N  81.0W   30 KT  35 MPH...INLAND
 36H  21/1200Z 35.4N  76.6W   35 KT  40 MPH...INLAND
 48H  22/0000Z 37.7N  71.9W   40 KT  45 MPH...OVER WATER
 60H  22/1200Z 40.8N  66.7W   40 KT  45 MPH
 72H  23/0000Z 44.5N  60.8W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  24/0000Z...DISSIPATED
 
$$
Forecaster Beven
 
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