[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 191458
TCDAT3

Tropical Depression Three Discussion Number   1
NWS National Hurricane Center Miami FL       AL032023
1100 AM AST Mon Jun 19 2023

Satellite images indicate that the tropical wave over the central
Atlantic has become better organized this morning.  GOES-16 1-min
visible imagery shows that the center has become well defined near
a developing central dense overcast with prominent convective
banding in the northern semicircle.  The initial intensity is set to
30 kt, based on Dvorak estimates from SAB and TAFB, and recent
satellite trends indicate this system is close to tropical-storm
status.

The initial motion estimate is 275/18 kt, a bit uncertain because
the center has just recently become trackable.  A large ridge of
high pressure over the central Atlantic Ocean is forecast to cause
the depression to move westward over the next several days. As the
system nears the Lesser Antilles late this week, the ridge should
weaken, causing the system to move more toward the west-northwest.
However, there is considerable uncertainty in how much of a right
turn could occur because it is somewhat tied to the intensity of the
cyclone.  A stronger system would tend to move more to the right due
to the upper-level flow, while a weaker system would continue more
westward into the Caribbean.  For now, this forecast lies near the
model consensus, and adjustments are likely in future advisories.
This should be considered a low confidence track forecast since
this type of forecast situation can result in large errors.

Environmental conditions appear conducive for strengthening over
the next few days, with a much warmer than normal ocean in the
depression's path, along with plentiful mid-level moisture and
light shear.  This should promote strengthening through midweek.
However, vertical wind shear is forecast to increase by most of the
model guidance around day 3 in response to an upper-level trough.
Thus the NHC forecast shows the intensity leveling off at the end
of the forecast, consistent with the middle of the guidance
envelope.  This intensity forecast is also more uncertain than
normal, due to the differences in the model suite, along with the
aclimatological nature of this system.

KEY MESSAGES:

1. The depression is forecast to strengthen and move across the
Lesser Antilles as a hurricane on Thursday and Friday, bringing a
risk of flooding from heavy rainfall, hurricane-force winds, and
dangerous storm surge and waves.

2. Given the larger than usual uncertainty in the track forecast,
it is too early to specify the location and magnitude of where
these hazards could occur. However, everyone in the Lesser
Antilles, Puerto Rico, and the Virgin Islands should closely monitor
updates to the forecast for this system and have their hurricane
plan in place.



FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 11.0N  40.3W   30 KT  35 MPH
 12H  20/0000Z 11.2N  42.9W   40 KT  45 MPH
 24H  20/1200Z 11.7N  45.9W   45 KT  50 MPH
 36H  21/0000Z 12.2N  48.6W   55 KT  65 MPH
 48H  21/1200Z 12.8N  51.2W   60 KT  70 MPH
 60H  22/0000Z 13.3N  53.9W   65 KT  75 MPH
 72H  22/1200Z 13.8N  56.3W   70 KT  80 MPH
 96H  23/1200Z 14.9N  61.5W   70 KT  80 MPH
120H  24/1200Z 16.5N  66.5W   65 KT  75 MPH

$$
Forecaster Blake/Kelly
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