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Hurricane Franklin Discussion Number  48
NWS National Hurricane Center Miami FL       AL082023
1100 AM AST Fri Sep 01 2023
 
The latest satellite images of Franklin indicate the system is
gradually losing tropical characteristics. The inner circulation of
the system is exposed, with a curved band of deep convection
displaced to the east of its center by strong westerly shear. The
low-level center is also losing definition and appears more
elongated than yesterday. A cold front is racing southeastward
toward Franklin, with rope clouds evident in visible satellite
imagery over the northern Atlantic. Recent scatterometer data shows
peak winds of 55-60 kt to the west of the center, with a larger area
of 34-kt winds in the northwest quadrant due to the approaching
front. Based on these data, the initial intensity is set at 65 kt.
 
In the short term, Franklin appears likely to remain at or near
hurricane-force intensity due to baroclinic forcing while it merges
with a frontal system over the northern Atlantic. This scenario is
supported by all the global models, which show a narrow band of
strong winds persisting within the western portion of the
circulation during the next 12-24 h (consistent with the
aforementioned ASCAT data). Soon thereafter, the extratropical
cyclone is forecast to weaken as the low moves deeper into the
mid-latitudes and gradually fills. The updated NHC intensity
forecast lies between the GFS and ECMWF in the near term, and then
trends toward the multi-model consensus later in the period.
 
Franklin is moving northeastward (50 degrees/16 kt) within the flow
between a deep-layer trough over the northwestern Atlantic and a
subtropical ridge over the central Atlantic. A somewhat faster
motion to the northeast is anticipated during the next day or so,
followed by a continued northeastward to east-northeastward motion
into early next week. Through 72 h, the updated NHC forecast lies
close to the previous prediction. As discussed with prior forecasts,
track uncertainty grows beyond day 3 regarding how much interaction
will occur between Franklin and a larger cut-off low meandering over
the eastern Atlantic. The latest NHC track has been adjusted south
of the previous forecast at days 4-5, but future adjustments could
be necessary as it still lies north of the TVCA and HCCA aids.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/1500Z 38.7N  55.6W   65 KT  75 MPH
 12H  02/0000Z 40.1N  52.4W   70 KT  80 MPH...POST-TROP/EXTRATROP
 24H  02/1200Z 42.5N  47.8W   65 KT  75 MPH...POST-TROP/EXTRATROP
 36H  03/0000Z 44.7N  43.4W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  03/1200Z 46.5N  39.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 60H  04/0000Z 47.9N  34.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  04/1200Z 48.6N  31.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  05/1200Z 49.0N  28.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  06/1200Z 49.5N  22.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Reinhart
 
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