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Tropical Storm Franklin Discussion Number   9
NWS National Hurricane Center Miami FL       AL082023
500 PM EDT Tue Aug 22 2023
 
Franklin is not a healthy tropical cyclone--and there is still some
question if it even is a tropical cyclone.  A NOAA Hurricane
Hunter aircraft investigating the system found a broad low-level
cyclonic wind field exposed to the west of the deep convection, but
this feature is well to the west of where we would have expected the
center to be.  At the same time, developing deep convection with
some mid-level turning is noted about 90 n mi to the east, which
would more closely follow persistence from previous forecasts.
Either way, Franklin is not well organized, and for now the initial
position is held closer to the convection in case a new center
re-forms in that area.  In fact, a dropsonde recently released by
the NOAA crew near the convection measured a surface pressure
of 1003 mb with winds of 32 kt, giving additional credence that a
new center could be forming.  The crew also reported that the SFMR
winds were running too high, and the highest 850-mb flight-level
wind was 41 kt, suggesting that Franklin's initial intensity is
probably down to about 35 kt.
 
The smoothed 12-hour motion remains northwestward (320 degrees) at
6 kt.  The track model guidance continues to insist that Franklin
will move slowly northward and then northeastward during the next 3
days or so, toward broad troughing located over the western
Atlantic.  This track should take Franklin northward across
Hispaniola during the next 12-36 hours, with the system then
turning northeastward over the western Atlantic.  By days 4 and 5,
a shortwave trough is expected to amplify near the northeastern
U.S. while a stronger mid-level ridge develops over the central
Atlantic, likely causing Franklin to turn back to the north by the
end of the forecast period.  Despite the possibility of center
re-formations, which could cause Franklin's track to jump around,
the model guidance is in good agreement on this general forecast
scenario, even if all the details are not yet ironed out.
 
The new intensity forecast probably has the biggest change from the
previous advisory, at least in the short term.  Little change in
strength is expected during the next 48 hours or so due to
Franklin's current disheveled state and its expected crossing of the
high terrain of Hispaniola on Wednesday.  Once Franklin moves over
the western Atlantic waters, a more diffluent upper-level
environment could foster some intensification, and the NHC forecast
continues to show the system becoming a hurricane by the end of the
5-day forecast period.  This forecast remains close to the HCCA and
IVCN consensus aids.
 
 
KEY MESSAGES:
 
1. Heavy rainfall from Franklin is expected across portions of
Hispaniola and Puerto Rico into Thursday. 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, where Tropical Storm
Warnings are in effect, beginning later tonight and continuing
through Wednesday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/2100Z 15.8N  71.4W   35 KT  40 MPH
 12H  23/0600Z 17.0N  71.3W   40 KT  45 MPH
 24H  23/1800Z 19.1N  70.9W   35 KT  40 MPH...OVER HISPANIOLA
 36H  24/0600Z 20.9N  70.3W   35 KT  40 MPH...OVER WATER
 48H  24/1800Z 22.0N  69.3W   40 KT  45 MPH
 60H  25/0600Z 22.5N  68.2W   45 KT  50 MPH
 72H  25/1800Z 22.9N  67.3W   50 KT  60 MPH
 96H  26/1800Z 24.3N  66.7W   60 KT  70 MPH
120H  27/1800Z 27.6N  67.7W   75 KT  85 MPH
 
$$
Forecaster Berg
 
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