Tropical Storm Gordon Discussion Number  13
NWS National Hurricane Center Miami FL       AL072024
1100 AM AST Sat Sep 14 2024

Gordon's center is exposed and located west of its deep convection. 
This structure is a symptom of the moderate westerly vertical wind 
shear that continues to plague the tropical storm. Gordon is also 
struggling with the entrainment of dry and stable airmass. Despite 
these environmental challenges, a recent scatterometer pass shows 
the cyclone maintaining 40 kt maximum sustained winds. This data is 
the basis for the initial intensity of this advisory, and agrees 
with a blend of the objective and subjective estimates. The 
scatterometer pass also shows a lopsided wind field, with tropical 
storm force winds limited to the northern semicircle of Gordon. In 
the southern semicircle, winds are weak and the vortex shows signs 
of elongation.

The cyclone continues to move into a dry and stable airmass, which 
in conjunction with the ongoing shear is forecast to induce 
weakening today and tonight. Gordon is forecast to become a tropical 
depression on Sunday. Thereafter, the forecast maintains the cyclone 
as a tropical depression through the early part of next week, but it 
is possible that the system degenerates into a remnant low or a 
surface trough during that time. In fact, the GFS model indicates 
convection could collapse as soon as tonight or early Sunday. The 
ECMWF model maintains pulsing convection a bit longer. By the middle 
of next week, the environment should become less hostile and allow 
for some re-strengthening of Gordon. The intensity forecast is 
largely unchanged from the previous advisory and remains on the 
lower end of the guidance beyond 72 h due to the uncertain future of 
the cyclone.

Gordon is tracking westward 280/8 kt, and a gradual turn toward the 
west-southwest with a slower forward speed is forecast over the next 
couple of days, in good agreement with the latest track guidance. 
Model spread increases beyond 72 h due to differences in intensity 
and the overall structure of Gordon at that time. The current 
forecast continues the system slowly west-southwestward due to lack 
of steering flow.  Towards the end of the forecast period, an 
approaching shortwave trough will weaken the mid-level subtropical 
ridge and would allow the system to turn northward. The updated 
track forecast is close to the previous advisory near the simple 
consensus aids, and shows a gradual turn toward the northwest and 
north beyond Day 3.


FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 20.1N  41.7W   40 KT  45 MPH
12H  15/0000Z 20.0N  43.0W   35 KT  40 MPH
24H  15/1200Z 19.9N  44.7W   30 KT  35 MPH
36H  16/0000Z 19.7N  46.1W   30 KT  35 MPH
48H  16/1200Z 19.6N  47.6W   30 KT  35 MPH
60H  17/0000Z 19.5N  49.0W   30 KT  35 MPH
72H  17/1200Z 19.5N  49.8W   30 KT  35 MPH
96H  18/1200Z 20.0N  50.9W   35 KT  40 MPH
120H  19/1200Z 21.5N  50.9W   40 KT  45 MPH

$$
Forecaster Kelly/Mahoney