000
WTNT42 KNHC 071436
TCDAT2

TROPICAL STORM GRACE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072015
1100 AM AST MON SEP 07 2015

Grace's cloud pattern has deteriorated somewhat this morning, with
the deep convection becoming fragmented and banding features less
evident than they were yesterday.  The initial intensity is
adjusted downward to 40 kt in agreement with data from a recent
ASCAT overpass, and in line with the latest subjective Dvorak
estimates from SAB and TAFB.  An upper-level trough to the northwest
of the tropical cyclone is producing some west-southwesterly
vertical shear on Grace.  The SHIPS model indicates that the shear
will increase over the next several days, which should inhibit
strengthening.  The official intensity forecast calls for little
change in strength during the next couple of days followed by
gradual weakening.  Grace is expected to degenerate into a remnant
low by the end of the forecast period.  This is similar to the
intensity model consensus, IVCN, but given the current state of the
system, Grace could weaken faster than indicated here.

The storm is moving a little more quickly toward the west this
morning, and the motion estimate is 275/15 kt.  For the next several
days, Grace will continue to be steered by the low- to mid-level
flow to the south of the subtropical ridge.  The GFS and ECMWF
global models show a rather brisk westward motion, perhaps partially
because the system opens up into a wave in the model predictions.
The official forecast is a bit faster than the previous one and
close to the latest model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 13.7N  35.9W   40 KT  45 MPH
 12H  08/0000Z 13.9N  38.1W   40 KT  45 MPH
 24H  08/1200Z 14.1N  41.5W   40 KT  45 MPH
 36H  09/0000Z 14.5N  45.0W   40 KT  45 MPH
 48H  09/1200Z 14.9N  48.1W   40 KT  45 MPH
 72H  10/1200Z 15.5N  54.5W   35 KT  40 MPH
 96H  11/1200Z 16.3N  61.0W   30 KT  35 MPH
120H  12/1200Z 17.0N  66.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch