[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 151434
TCDAT5

Tropical Storm Teddy Discussion Number  12
NWS National Hurricane Center Miami FL       AL202020
1100 AM AST Tue Sep 15 2020

Teddy's structure is slowly improving. Visible and IR imagery
indicate that inner-core convection has increased, despite the
continued presence of dry slots. The latest Dvorak intensity
estimates from TAFB and SAB support the initial intensity of 55 kt.

Teddy is still heading west-northwestward for the moment with a
forward speed estimate of 11 kt. Teddy will likely turn
northwestward today and continue steadily moving northwestward along
the southwest periphery of a ridge over the central Atlantic for the
next several days. In fact, all available guidance indicates that
once it makes that northwestward turn, Teddy will barely deviate
from its heading or forward speed for the rest of the week. The
latest NHC track forecast is virtually identical to the previous
one. The model spread is smaller than usual and confidence in the
track forecast is high.

Teddy's low shear and warm SST environment should be conducive for
further strengthening, and the NHC intensity forecast is largely
unchanged. Some dry air in the environment could restrict Teddy's
intensification rate, but is not expected to prevent Teddy from
becoming a hurricane later today or tonight. Continued strengthening
is expected thereafter and Teddy is forecast to become a major
hurricane within the next few days. On the whole, the intensity
guidance is a little lower at the longer-range times, so the NHC
forecast at days 4 and 5 is at the very top end of the guidance. I'd
rather see a more consistent signal from the models before making a
larger change to the forecast, especially given the impressive
depiction of Teddy in the global model forecasts at that time.

The 34 kt wind radii were expanded to the northwest of Teddy based
on data from an 1136 UTC ASCAT-A overpass.

FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 14.0N  47.0W   55 KT  65 MPH
 12H  16/0000Z 14.9N  48.2W   65 KT  75 MPH
 24H  16/1200Z 16.1N  49.5W   75 KT  85 MPH
 36H  17/0000Z 17.4N  50.8W   85 KT 100 MPH
 48H  17/1200Z 18.9N  52.3W   95 KT 110 MPH
 60H  18/0000Z 20.3N  53.6W  100 KT 115 MPH
 72H  18/1200Z 21.5N  55.0W  105 KT 120 MPH
 96H  19/1200Z 24.0N  57.4W  110 KT 125 MPH
120H  20/1200Z 27.1N  60.0W  100 KT 115 MPH

$$
Forecaster Zelinsky
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