000
WTNT44 KNHC 210835
TCDAT4

Tropical Storm Chantal Discussion Number   2
NWS National Hurricane Center Miami FL       AL042019
500 AM AST Wed Aug 21 2019

Chantal has changed little overnight. A small area of deep
convection has persisted northeast of the tropical storm's exposed
surface center. Given the steady-state structure of the cyclone, the
initial intensity has been held at 35 kt based on earlier ASCAT
data.

Only minor adjustments were made to the NHC track and intensity
forecasts, the most substantial of which is that Chantal is now
expected to become a remnant low within 96 h. The tropical storm is
surrounded by dry air and will be moving over marginal SSTs for the
next couple of days. As a result of this unfavorable environment,
Chantal is expected to weaken to a tropical depression by 48 h. Most
of the dynamical models indicate that the cyclone will lose all of
its convection and become post-tropical soon after, but the official
forecast conservatively maintains the system as a tropical cyclone
for 72 h. The official intensity forecast is near a consensus of the
GFS, HMON, and HWRF models.

The tropical storm is moving quickly eastward, but is forecast to
slow and turn southeastward by Thursday. It should then turn toward
the south on Friday as it moves around the northeast periphery of a
low- to mid-level ridge centered over the central Atlantic. The
track guidance is in good agreement on the forecast, at least as
long as Chantal remains a tropical cyclone. The uncertainty in the
track forecast is higher after the cyclone becomes a remnant low,
but most of the guidance generally suggests that Chantal will become
trapped in weak steering flow and meander over the North Atlantic
for a couple days thereafter.

FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 40.3N  53.7W   35 KT  40 MPH
 12H  21/1800Z 40.2N  50.4W   35 KT  40 MPH
 24H  22/0600Z 39.6N  46.3W   35 KT  40 MPH
 36H  22/1800Z 38.4N  43.4W   35 KT  40 MPH
 48H  23/0600Z 37.2N  42.0W   30 KT  35 MPH
 72H  24/0600Z 35.3N  42.4W   30 KT  35 MPH
 96H  25/0600Z 35.5N  44.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  26/0600Z 37.5N  44.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky