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TROPICAL DEPRESSION GRACE DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072015
1100 AM AST TUE SEP 08 2015

After the overnight burst of deep convection, thunderstorm activity
has diminished and the overall cloud pattern remains disorganized.
Data from a recent ASCAT overpass show that Grace's maximum winds
have decreased to near 30 kt, so the system is being downgraded to
a tropical depression on this advisory.  The cyclone is forecast
to move through an environment of increasing vertical shear and dry
mid-level air for the next few days.  These unfavorable factors
should cause the system to weaken further, and to degenerate
into a remnant low pressure area over the next day or two.  The
official intensity forecast is the same as the previous one, and is
slightly below the latest intensity model consensus.  It is
possible that Grace could open up into a wave during the next few
days, as indicated by the global models.

The cyclone continues to move westward at a fairly rapid pace, with
the motion estimate remaining at 275/17 kt.  The steering pattern
is expected to remain uncomplicated.  Grace or its remnant should
continue to move west or slightly north of west, to the south of
a low- to mid-level subtropical ridge throughout the forecast
period.  The official track forecast is an update of the previous
one and remains close to the dynamical model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 14.3N  42.8W   30 KT  35 MPH
 12H  09/0000Z 14.4N  45.4W   30 KT  35 MPH
 24H  09/1200Z 14.8N  48.8W   30 KT  35 MPH
 36H  10/0000Z 15.3N  52.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  10/1200Z 15.8N  55.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  11/1200Z 16.6N  62.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  12/1200Z...DISSIPATED

$$
Forecaster Pasch

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