[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 220236
TCDAT2

Tropical Depression Seven Discussion Number   2
NWS National Hurricane Center Miami FL       AL072020
1100 PM AST Tue Jul 21 2020

The depression remains quite small in size and its cloud pattern
consists of a compact central dense overcast and some convective
bands on its west side.  The latest satellite intensity estimates
and a recent ASCAT pass support maintaining the initial intensity
at 30 kt.

The initial motion is west-northwestward at 8 kt.  The track
forecast appears fairly straightforward.  A strengthening
deep-layer subtropical ridge to the north of the depression should
cause the system to accelerate some toward the west or
west-northwest during the next several days.  This steering pattern
should take the cyclone across the eastern Caribbean Islands and
into the Caribbean Sea this weekend.  The models are in fairly good
agreement and there is high confidence in the track forecast.

The intensity forecast is much trickier.  The models continue to
differ on the evolution of the depression, with the
statistical-dynamical models and some of the hurricane regional
models showing the system becoming a hurricane within the next few
days.  Conversely, the global models show little change in strength
and even dissipate the system as it moves across the eastern
Caribbean Sea.  The global models seem to indicate that a
combination of the cyclone's fast forward speed and associated
shear, and dry air entrainment should prevent strengthening or lead
to weakening.  Given the large amount of uncertainty, only small
changes were made to the previous prediction.  This forecast lies a
little below the consensus models giving slightly more weight to
the global model solutions.  It should be noted that small systems
like Tropical Depression Seven are often difficult to predict as
they are more likely to fluctuate in strength compared to
larger cyclones.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 10.0N  41.3W   30 KT  35 MPH
 12H  22/1200Z 10.2N  42.7W   35 KT  40 MPH
 24H  23/0000Z 10.3N  45.0W   45 KT  50 MPH
 36H  23/1200Z 10.4N  47.5W   50 KT  60 MPH
 48H  24/0000Z 10.5N  50.1W   55 KT  65 MPH
 60H  24/1200Z 10.8N  52.9W   55 KT  65 MPH
 72H  25/0000Z 11.3N  56.0W   55 KT  65 MPH
 96H  26/0000Z 12.4N  63.1W   50 KT  60 MPH
120H  27/0000Z 13.7N  70.7W   45 KT  50 MPH

$$
Forecaster Cangialosi
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