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Tropical Depression ELEVEN


Tropical Depression Eleven Discussion Number   2
NWS National Hurricane Center Miami FL       AL112018
500 AM AST Sat Sep 22 2018

Deep convection remains displaced to the east of the depression's
center due to 30-40 kt of westerly shear.  Although Dvorak final-T
numbers from TAFB and SAB have decreased since yesterday--now a
consensus T1.0--the initial intensity is held, perhaps generously,
at 30 kt.  Strong westerly shear is expected to persist for several
days, which at the very least will prevent the depression from
getting any better organized.  Since the global models show the
depression opening up into a trough in about 24 hours, the new NHC
intensity forecast brings down the winds a little faster, shows the
system becoming a remnant low by 36 hours, and dissipates the low
entirely by 48 hours well east of the Windward Islands.  This
evolution could certainly occur more quickly than indicated by the
official forecast.

The center of the depression has not been moving much, and it's
possible the sheared convection is trying to pull it back toward
the east.  However, the average motion over the past 12 hours is
westward, or 270/4 kt.  The track guidance insists that the
depression should move slowly west-northwestward over the next
couple of days, but given that the system has not made any
northward progress, I elected to skirt the southern edge of the
guidance envelope.  This new forecast is a little south of the
previous NHC track prediction.


INIT  22/0900Z 13.0N  53.5W   30 KT  35 MPH
 12H  22/1800Z 13.3N  54.3W   30 KT  35 MPH
 24H  23/0600Z 13.6N  55.4W   25 KT  30 MPH
 36H  23/1800Z 13.8N  56.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  24/0600Z...DISSIPATED

Forecaster Berg