[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 151458
TCDAT5

Tropical Depression Fifteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL152023
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Fri Sep 15 2023

1-min GOES-East visible imagery indicates improved organization of
Invest 97, with a well-defined surface center forming since
sunrise, along with large curved banding features.  Thus the system
is designated as a tropical depression, and the initial intensity
is set to 30 kt, in closest agreement with the TAFB Dvorak
classification.

Our estimate of initial motion is northwestward at 10 kt, though
this is uncertain due to the recent center formation.  A
subtropical ridge over the central Atlantic should be the dominant
steering mechanism during the next several days, sending the system
on a steady northwestward track.  For a first forecast, guidance is
in remarkably good agreement, and the official forecast lies near
or west of the model consensus.  Despite the good model agreement,
there is still some long-range uncertainty in how far west this
system moves, which partially depends on the strength of the
subtropical ridge in the wake of Tropical Storm Margot.

The depression is forecast to gradually intensify over the next
couple of days as moderate northeasterly shear and the initial broad
cyclone structure could provide a check on the intensification
rate.  By early next week, this system is forecast to move over
near record warm sea-surface temperatures for the region in light
shear conditions. It probably sounds like a broken record at this
point in the season, but rapid intensification is a significant
possibility, and the official forecast could be conservative below.
The intensity forecast is near or above the intensity consensus,
only leveling off at 120 hours due to gradual SST cooling and the
possibility of eyewall replacement cycles, as suggested by the HAFS
model suite.


FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 14.4N  43.8W   30 KT  35 MPH
 12H  16/0000Z 15.5N  44.7W   35 KT  40 MPH
 24H  16/1200Z 17.2N  46.0W   40 KT  45 MPH
 36H  17/0000Z 18.9N  47.9W   50 KT  60 MPH
 48H  17/1200Z 20.5N  49.6W   60 KT  70 MPH
 60H  18/0000Z 22.0N  51.2W   70 KT  80 MPH
 72H  18/1200Z 23.4N  52.9W   85 KT 100 MPH
 96H  19/1200Z 26.0N  56.8W  105 KT 120 MPH
120H  20/1200Z 29.0N  60.0W  100 KT 115 MPH

$$
Forecaster Churchill/Blake/Lamers
This weather bulletin was brought to you by:
www.nashvilleweather.net