[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 212036
TCDAT2

Tropical Depression Seven Discussion Number   1
NWS National Hurricane Center Miami FL       AL072020
500 PM AST Tue Jul 21 2020

Satellite imagery and scatterometer data indicate that the low
pressure area located over the central tropical Atlantic has a
well-defined circulation and sufficient organized convection to be
designated a tropical depression.  Thus, advisories are being
initiated on Tropical Depression Seven.  The initial intensity is
set at 30 kt in best agreement with the subjective satellite
intensity estimate from TAFB.

The initial motion is 300/7.  The depression is south of a strong
subtropical ridge over the central Atlantic, and over the next
several days it should turn generally westward and accelerate as it
encounters the easterly flow associated with the ridge.  The ECMWF,
GFS, and UKMET models are in reasonably good agreement on their
track forecasts, and the NHC official forecast is close to them and
the various consensus models.

The intensity forecast is lower confidence.  The GFS, ECMWF, and
UKMET models forecast the cyclone to be dissipated or be a weak low
by the 120 h point, likely due to to some vertical shear and dry
air entrainment.  On the other hand, the SHIPS-based guidance and
the HWRF forecast the system to be a hurricane at 120 h, shrugging
off the shear and dry air.  The NHC intensity forecast will be a
compromise between these extremes, showing a peak intensity of 55
kt in 60-72 h followed by some weakening based on the global models.
The cyclone is small in size, and as a result it could change
intensity - both up and down - faster than what is currently
forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z  9.8N  40.4W   30 KT  35 MPH
 12H  22/0600Z 10.1N  41.7W   35 KT  40 MPH
 24H  22/1800Z 10.3N  43.9W   40 KT  45 MPH
 36H  23/0600Z 10.3N  46.3W   45 KT  50 MPH
 48H  23/1800Z 10.4N  49.0W   50 KT  60 MPH
 60H  24/0600Z 10.6N  51.6W   55 KT  65 MPH
 72H  24/1800Z 11.0N  54.7W   55 KT  65 MPH
 96H  25/1800Z 12.0N  61.0W   50 KT  60 MPH
120H  26/1800Z 13.5N  68.5W   45 KT  50 MPH

$$
Forecaster Beven
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