[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 230859
TCDAT3

Tropical Storm Franklin Discussion Number  11
NWS National Hurricane Center Miami FL       AL082023
500 AM EDT Wed Aug 23 2023

Franklin's cloud pattern continues to become gradually better
organized with a large convective band evident over the eastern
semicircle of the circulation.  There is still some westerly shear
over the system, and most of the deep convection is confined to the
northeast and southeast quadrants of the storm.  Franklin appears to
be producing high-level anticyclonic outflow which is being undercut
by westerlies just below the outflow level.  Subjective Dvorak
intensity estimates range from 35 to 45 kt, and most of the
objective estimates are in this range as well.  A scatterometer
overpass from several hours ago indicated maximum winds near 40 kt.
The current intensity is set at 45 kt.

Although the center remains difficult to locate, satellite center
fixes from TAFB and SAB and continuity suggest a motion of about
010/9 kt.  Franklin is moving through a weakness in the mid-level
subtropical ridge.  During the next couple of days, the cyclone is
forecast to turn toward the east-northeast and move along the
northwestern side of a mid-level anticyclone, and south of a
higher-latitude trough.  In 3 to 5 days, as the trough lifts out and
a mid-level ridge to the west and northwest of Franklin builds
slightly, the system is expected to turn northward and
north-northwestward.  The official track forecast is again close to
the HCCA consensus and very similar to the previous advisory's
prediction.

Land interaction with the mountains of Hispaniola today are likely
to disrupt Franklin's circulation, and the amount of weakening
shown by the NHC short-term intensity forecast may be conservative.
After the cyclone moves over the Atlantic, strengthening is
anticipated.  However, the global models show significant shear
associated with an upper-level cyclone over the southwestern
Atlantic near 70W in 3-5 days, and this is also indicated in the
SHIPS guidance.  Because of this, the official intensity forecast
is near the low end of the model guidance and similar to the LGEM
prediction.  This is just slightly higher than the previous
official forecast.


KEY MESSAGES:

1. Heavy rainfall from Franklin is expected across much of
Hispaniola into Thursday. The heavy rainfall is expected to produce
significant and potentially life-threatening flash and urban
flooding as well as mudslides, particularly over central Hispaniola
today.

2. Franklin is bringing tropical storm conditions to portions of the
Dominican Republic and Haiti, where Tropical Storm Warnings are in
effect, and tropical storm conditions are expected to begin within
the Turks and Caicos Islands later today or tonight.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 17.4N  71.3W   45 KT  50 MPH
 12H  23/1800Z 19.0N  71.0W   35 KT  40 MPH...INLAND
 24H  24/0600Z 21.1N  70.5W   35 KT  40 MPH
 36H  24/1800Z 22.2N  69.3W   45 KT  50 MPH
 48H  25/0600Z 22.7N  68.1W   55 KT  65 MPH
 60H  25/1800Z 23.0N  67.0W   60 KT  70 MPH
 72H  26/0600Z 23.3N  66.4W   65 KT  75 MPH
 96H  27/0600Z 25.8N  66.8W   75 KT  85 MPH
120H  28/0600Z 29.5N  68.0W   80 KT  90 MPH

$$
Forecaster Pasch
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