August 21, 2019
Issued at Wed Aug 21 2019
Tropical Storm Chantal Discussion Number
National Hurricane Center Miami FL
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
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