000
WTNT42 KNHC 072035
TCDAT2

TROPICAL STORM GRACE DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072015
500 PM AST MON SEP 07 2015

Deep convection associated with Grace has been waning today, and
banding features are not evident.  In fact, if the convection does
not make a comeback soon, the system will be too weak to classify
using the Dvorak technique.  The current intensity is held at 40
kt, mainly based on the winds from an earlier ASCAT overpass.
Westerly shear on Grace is forecast to increase over the next
couple of days, but assuming that the convection will make at least
a little comeback, the system is forecast to maintain tropical storm
intensity for a day or two.  This is consistent with the latest
intensity model consensus.  The new NHC intensity forecast shows a
much sooner degeneration to a remnant low, compared to the previous
advisory. Clearly, Grace could dissipate much sooner than shown
here.

The storm continues its rapid westward motion, even a little faster
than earlier.  A low- to mid-level ridge to the north of Grace
should maintain a swift motion toward the west or slightly north of
west over the next few days.  The official track forecast remains
close to the latest dynamical model consensus.  This is not quite
as fast as the ECMWF, but that model opens the system up into a
wave within 48 hours.

The 34-kt wind radii have been modified, based on earlier
scatterometer data that showed a lack of winds to tropical storm
force over the southern semicircle of the cyclone.

FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 14.0N  37.5W   40 KT  45 MPH
 12H  08/0600Z 14.1N  40.0W   40 KT  45 MPH
 24H  08/1800Z 14.3N  43.3W   35 KT  40 MPH
 36H  09/0600Z 14.7N  46.5W   35 KT  40 MPH
 48H  09/1800Z 15.2N  50.0W   30 KT  35 MPH
 72H  10/1800Z 16.0N  57.0W   25 KT  30 MPH...POST-TROPICAL
 96H  11/1800Z...DISSIPATED

$$
Forecaster Pasch