000
WTNT42 KNHC 060244
TCDAT2

TROPICAL STORM GRACE DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072015
1100 PM AST SAT SEP 05 2015

Most of the deep convection associated with Grace is located west
and southwest of the estimated center position, consistent with
light-to-moderate easterly shear analyzed over the cyclone by
UW-CIMSS and the SHIPS model. The initial intensity remains 35 kt
based on the latest Dvorak classifications from TAFB and SAB. Grace
will be moving over warm waters and in a low shear environment for
the next 24 to 36 hours, which should support some strengthening.
After that time, the shear becomes westerly and increases with the
cyclone moving over slightly cooler waters. As a result, much of the
intensity guidance suggests that Grace will weaken later in the
period, with dissipation also possible. The new NHC intensity
forecast is similar to the previous one and is close to the latest
IVCN intensity consensus.

The initial motion estimate is 280/12. Grace should continue moving
generally westward to west-northwestward to the south of a
subtropical ridge for the next several days. The track model
guidance is in good agreement on this scenario, although there is
some variability in forward speed. The new NHC track forecast is
an update of the previous one and lies a little south of the
consensus given that Grace is forecast to be weaker by the end
of the period. This track is close to the latest predictions from
the GFS model and the FSU Superensemble.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 12.8N  27.5W   35 KT  40 MPH
 12H  06/1200Z 13.0N  29.5W   40 KT  45 MPH
 24H  07/0000Z 13.3N  32.3W   45 KT  50 MPH
 36H  07/1200Z 13.6N  35.1W   50 KT  60 MPH
 48H  08/0000Z 14.1N  38.0W   45 KT  50 MPH
 72H  09/0000Z 14.8N  44.2W   45 KT  50 MPH
 96H  10/0000Z 15.3N  49.5W   40 KT  45 MPH
120H  11/0000Z 16.0N  54.5W   35 KT  40 MPH

$$
Forecaster Brennan