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Tropical Storm Chantal Discussion Number 1
NWS National Hurricane Center Miami FL AL042019
1100 PM AST Tue Aug 20 2019
Recent scatterometer wind data and passive microwave satellite
images indicate that the small low pressure system that the NHC has
been monitoring for the past few days has developed a well-defined
surface wind circulation and contains tropical-storm-force winds
south of the cyclone's center. Therefore, the low has become
Tropical Storm Chantal.
The initial motion estimate is 085/19 kt. NHC model guidance is in
excellent agreement that Chantal will move eastward around the
northern periphery of the Bermuda-Azores high and gradually slow
down during the next 48 hours. Thereafter, the cyclone is forecast
to drop southward around the eastern portion of the ridge, possibly
stalling over warmer waters. The NHC forecast track lies close to
the consensus models HCCA and TVCN.
Chantal is expected to remain in a moderate southwesterly to
westerly vertical wind shear regime for the next 48 hours or so,
followed by a significant decrease in the shear through 120 h. After
48 hours, the southward motion is also expected to move Chantal over
warmer water with SSTs around 27C. However, mid-level moisture is
expected to be quite sparse with humidity values forecast to be less
than 40 percent based on the GFS and ECMWF SHIPS intensity guidance.
Therefore, little or no significant intensification is expected
throughout the forecast period, and the official intensity forecast
closely follows a blend of the HCCA and IVCN consensus models.
Although the official forecast calls for Chantal to remain a
tropical cyclone through the 120 h, the abundance of dry air that
the cyclone will be moving through could result in erosion of the
deep convection sooner than currently expected.
FORECAST POSITIONS AND MAX WINDS
INIT 21/0300Z 40.2N 56.2W 35 KT 40 MPH
12H 21/1200Z 40.3N 52.6W 35 KT 40 MPH
24H 22/0000Z 40.2N 48.5W 35 KT 40 MPH
36H 22/1200Z 39.0N 44.7W 35 KT 40 MPH
48H 23/0000Z 37.4N 42.3W 35 KT 40 MPH
72H 24/0000Z 34.9N 42.5W 35 KT 40 MPH
96H 25/0000Z 34.6N 44.8W 35 KT 40 MPH
120H 26/0000Z 36.0N 44.8W 35 KT 40 MPH