ZCZC MIATCDAT5 ALL
TTAA00 KNHC DDHHMM
 
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
 
NNNN