Tropical Depression Seven Advisory Number 1
NWS National Hurricane Center Miami FL AL072020
500 PM AST Tue Jul 21 2020
...TROPICAL DEPRESSION FORMS OVER THE CENTRAL TROPICAL ATLANTIC...
SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...9.8N 40.4W
ABOUT 1185 MI...1905 KM WSW OF THE CABO VERDE ISLANDS
ABOUT 1420 MI...2285 KM E OF THE SOUTHERN WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 500 PM AST (2100 UTC), the center of Tropical Depression Seven
was located near latitude 9.8 North, longitude 40.4 West. The
depression is moving toward the west-northwest near 8 mph (13 km/h).
A turn toward the west with an increase in forward speed is
expected tonight and Wednesday, and that motion should continue
through Friday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Strengthening is forecast during the next couple of days, and the
depression is expected to become a tropical storm tonight or
Wednesday.
The estimated minimum central pressure is 1009 mb (29.80 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 1100 PM AST.
$$
Forecaster Beven
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