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Potential Tropical Cyclone Six Discussion Number   3
NWS National Hurricane Center Miami FL       AL062018
1100 PM AST Thu Aug 30 2018

Satellite imagery indicates that the disturbance is gradually
becoming better organized.  However, the convection is not yet well
enough organized to call the system a tropical cyclone, and recent
scatterometer data show that the system still lacks a well-defined
center of circulation.  The scatterometer did indicate winds of
25-30 kt, so the initial intensity is nudged upward to 30 kt.

The system should be in an environment of light to moderate
easterly vertical shear for the next three to four days.  Sea
surface temperatures decrease along the forecast track during this
time, though, reaching 26C by 72-96 h.  The intensity guidance
suggests that the system should at least slowly develop despite the
falling SSTs, and based on this the new intensity forecast calls for
it to become a tropical depression in about 12 h, a tropical storm
in 12-24 h, and a hurricane near the 96-h point.  While the system
is expected to reach warmer SSTs near the end of the forecast
period, it is also expected to encounter westerly shear at that
time, which should limit additional intensification.

The initial motion is a somewhat uncertain 280/11.  The trade winds
on the south side of the subtropical ridge should steer the system
west-northwestward with an increase in forward speed during the
next 3-4 days, passing near or over the southern Cabo Verde Islands
Friday or Friday night.  Near the end of the forecast period, a
turn toward the northwest is forecast as the system approaches a
weakness in the ridge.  The new track forecast is again little
changed from the previous forecast and lies near the various
consensus models.  It should be noted that some adjustments to the
early parts of the forecast track may occur until the center
becomes better defined.


FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 13.2N  20.9W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  31/1200Z 13.7N  22.3W   30 KT  35 MPH...TROPICAL DEPRESSION
 24H  01/0000Z 14.5N  24.9W   40 KT  45 MPH
 36H  01/1200Z 15.3N  27.7W   45 KT  50 MPH
 48H  02/0000Z 16.0N  30.4W   50 KT  60 MPH
 72H  03/0000Z 17.5N  35.5W   60 KT  70 MPH
 96H  04/0000Z 19.0N  40.0W   65 KT  75 MPH
120H  05/0000Z 21.5N  44.0W   65 KT  75 MPH

$$
Forecaster Beven

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