[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 190241
TCDAT5

Tropical Storm Don Discussion Number  20
NWS National Hurricane Center Miami FL       AL052023
300 AM GMT Wed Jul 19 2023

Don's convective structure continues to sputter along this evening,
with only a small area of cold cloud tops below -50C centered just
to the east of the low-level center. However, there has been some
modest improvement of the low-level structure on microwave imagery,
with some curved bands on storm's east side. The latest subjective
and objective Dvorak classifications remain around 35 kt, and that
will remain the intensity for this advisory.

While the ongoing convection is relatively meager, it is currently
occuring within Don's radius of maximum wind. High-resolution
guidance (HAFS-A and HWRF) does show this convection persisting near
the center, possibly helping to develop a smaller wind core over the
next several days. Don is also expected to continue moving over
gradually warmer waters to near 26 C in 24-36 hours as the
mid-levels moisten and shear remains under 15 kt. Thus, some gradual
intensification continues to be shown over the next couple of days,
peaking the system at 45 kt in about 48 h. After that time, Don's
intensity is likely to be influenced by its future track,
with a more westward motion taking Don toward warmer waters.
However, the current NHC forecast track takes Don closer to the
cold wake it generated over the weekend. In fact, the latest SHIPS
guidance shows SSTs decreasing again after 48 h, and thus little
additional intensification is shown after that time, which remains
a bit under the consensus aids. By days 4-5, Don should be moving
beyond the north wall of the Gulf Steam, likely losing its
remaining convection and becoming post-tropical.

Don appears to be slowing its forward motion tonight, with the
latest estimated motion at 190/3 kt. This slowdown is likely in
preparation for the system to turn southwestward and westward over
the next 24-36 h as an amplified subtropical ridge grows poleward
over Don. This ridge is then expected to continue sliding eastward
and merge with another subtropical ridge just offshore of
northwestern Africa, which should provide an avenue for Don to
escape northward and then northeastward by the end of the forecast
period. There was not a lot of changes with the track guidance this
cycle, as the weaker ECMWF remains on the eastern side of the
guidance, while the stronger HAFS and GFS remain on the western
side. The NHC track forecast is quite similar to the prior
one, favoring a slightly more eastward track given that Don is
forecast to be on the weaker end of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0300Z 34.3N  39.0W   35 KT  40 MPH
 12H  19/1200Z 33.8N  39.3W   35 KT  40 MPH
 24H  20/0000Z 33.5N  40.5W   40 KT  45 MPH
 36H  20/1200Z 33.8N  41.7W   40 KT  45 MPH
 48H  21/0000Z 34.6N  43.5W   45 KT  50 MPH
 60H  21/1200Z 35.6N  45.6W   45 KT  50 MPH
 72H  22/0000Z 37.3N  47.7W   45 KT  50 MPH
 96H  23/0000Z 42.1N  49.6W   45 KT  50 MPH
120H  24/0000Z 47.2N  44.6W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Papin
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