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Tropical Storm Franklin Discussion Number   3
NWS National Hurricane Center Miami FL       AL082023
500 AM AST Mon Aug 21 2023
 
Franklin's cloud pattern has not become significantly better 
organized overnight.  The system is producing several clusters of 
bursting very deep convection, but convective banding features are 
not well defined at this time.  Based on microwave imagery, the 
cyclone center is apparently located near the western edge of the 
overall convective mass.  The current intensity is held at 45 kt in 
agreement with a subjective Dvorak satellite classification from 
TAFB.  This value is also supported by objective intensity estimates 
from UW-CIMSS.

The storm continues moving generally westward, with a motion 
estimate of 270/10 kt.  Franklin's forecast track is somewhat 
problematic.  A weakness in the subtropical ridge is expected to 
cause the tropical cyclone to turn northward in 24 hours or so.  
This should result in Franklin crossing Hispaniola in the 48 hour 
time frame.  After moving into the Atlantic, Franklin should turn 
northeastward while interacting with a mid-level cyclonic 
circulation.  By late in the forecast period, the mid-level cyclone 
lifts out which could allow Franklin to turn more to the left.  
However there is more than the usual amount of uncertainty in the 
3-5 day track prediction, with lots of spread in the model guidance. 
The official forecast, like the previous one, is near the middle of 
the guidance envelope and close to the model consensus.
 
The flow on the south side of a broad upper-level trough to the 
northwest of Franklin is causing moderate southwesterly vertical 
wind shear over the storm.  Dynamical guidance such as the SHIPS 
model indicate that Franklin will remain in an environment of 
moderate shear for the next several days, and the interaction with 
the mountainous land mass of Hispaniola should temporarily disrupt 
Franklin's circulation.  The current thinking is that the shear will 
not be strong enough to prevent the system from eventually becoming 
a hurricane over the southwest Atlantic.  The official intensity 
forecast follows the model consensus.  

 
KEY MESSAGES:
 
1. Heavy rainfall from Franklin is expected across portions of 
Puerto Rico and Hispaniola through the middle of the week.  The 
heavy rainfall may produce areas of flash and urban flooding as well 
as river rises and mudslides.  Across Hispaniola, significant and 
potentially life-threatening flash flooding is possible Tuesday into 
Wednesday.
 
2. Franklin is expected to bring tropical storm conditions to
portions of the Dominican Republic and Haiti beginning on Tuesday
where Tropical Storm Warnings are in effect.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 15.0N  69.2W   45 KT  50 MPH
 12H  21/1800Z 15.0N  70.4W   50 KT  60 MPH
 24H  22/0600Z 15.3N  71.1W   50 KT  60 MPH
 36H  22/1800Z 16.7N  71.2W   55 KT  65 MPH
 48H  23/0600Z 18.8N  70.9W   45 KT  50 MPH...INLAND
 60H  23/1800Z 20.9N  70.2W   45 KT  50 MPH...OVER WATER
 72H  24/0600Z 22.5N  69.0W   55 KT  65 MPH
 96H  25/0600Z 24.5N  66.0W   60 KT  70 MPH
120H  26/0600Z 26.0N  64.0W   70 KT  80 MPH
 
$$
Forecaster Pasch
 
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