[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 171456
TCDAT5

Tropical Depression Don Discussion Number  14
NWS National Hurricane Center Miami FL       AL052023
300 PM GMT Mon Jul 17 2023

Satellite images indicate that Don continues to produce a cluster of
deep convection, displaced east of the center due to shear. Despite
the cool waters, this deep convection has persisted overnight, and
the cloud pattern most resembles a sheared tropical cyclone,
although the circulation remains elongated. This structure is
confirmed by the latest TAFB Dvorak estimate, which gave a tropical
classification for the first time at 12 UTC. Thus, Don is changed to
a tropical cyclone on this advisory, although it is still a 30-kt
depression on the basis of a recent scatterometer pass at 1229 UTC
that showed a small area of winds around 30 kt.

Don is moving east-southeastward at about 12 kt, with a better
estimate of motion available due to the aforementioned scatterometer
pass.  The depression is about a quarter of the way through making a
large anticyclonic loop over the central Atlantic, forced by a
blocking ridge to its north.  The new forecast is shifted to the
east during the next few days as guidance has trended faster with a
more vertically intact cyclone structure noted.  In the long range,
the blocking ridge shifts eastward, allowing Don to turn
northwestward and cross over its own path in about 5 days.  While
the ECMWF still remains east of most of the other guidance, the
model consensus is close to the previous forecast, so the new track
forecast is about the same as the last prediction.

The depression is expected to move over warmer waters by midweek,
though some increase in shear could reduce the chances for
significant restrengthening (and the waters are only 25 degrees C
or so).  Still, basically all of the models now bring this to a
tropical storm within a few days, and the new forecast continues to
follow suit.  At long range, the SSTs start to decrease again, and
the system is forecast to cross its own path, resulting in less
instability due to a presumed cool wake from the storm.  I've
elected to raise the forecast 5 kt in about 4 days, but it is still
below most of the guidance, as the environment just doesn't seem
that conducive for a significant increase in winds.


FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 38.6N  42.9W   30 KT  35 MPH
 12H  18/0000Z 37.7N  41.1W   30 KT  35 MPH
 24H  18/1200Z 36.0N  39.8W   30 KT  35 MPH
 36H  19/0000Z 34.5N  39.3W   30 KT  35 MPH
 48H  19/1200Z 33.8N  39.8W   35 KT  40 MPH
 60H  20/0000Z 33.4N  40.8W   35 KT  40 MPH
 72H  20/1200Z 33.7N  42.0W   40 KT  45 MPH
 96H  21/1200Z 35.8N  45.5W   45 KT  50 MPH
120H  22/1200Z 39.5N  49.0W   40 KT  45 MPH

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