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Tropical Depression Nine-E Discussion Number   2
NWS National Hurricane Center Miami FL       EP092021
800 PM PDT Fri Jul 30 2021
 
The depression is struggling. Aside from a stray cell or two, the 
cyclone has been nearly devoid of deep convection since the diurnal 
convective minimum earlier this evening. AMSR data near 22Z 
indicated that multiple weak swirls may be embedded within the 
broader circulation sampled earlier today by ASCAT. The initial 
intensity remains 25 kt for this advisory.
 
Confidence in the track forecast is unusually low. The initial 
position, and therefore also the motion estimate, is highly 
uncertain due to the disorganized nature of the depression. On top 
of that, the track guidance is in extremely poor agreement regarding 
even the basics of the future track of the cyclone. Hilda, located 
relatively close to the east (about 10 degrees) may have some impact 
on the depression's track during the next 5 days. In fact, the GFS 
explicitly forecasts that a binary interaction will occur between 
the two tropical cyclones. Other models like the ECMWF move both 
systems steadily, and mostly independently, westward. As a course of 
least regret, the NHC track forecast is close to the previous 
advisory and multi-model consensus, between those two scenarios. 
Large changes to the track forecast may be necessary on Saturday if 
the track guidance begins to converge on a single solution.

Warm water and moderate shear could allow for some strengthening 
during the next few days, if the depression can redevelop and 
sustain organized convection. The NHC intensity forecast assumes 
that will happen to some degree and has not been substantially 
changed. It is also possible that dry air in the environment could 
continue to inhibit convection as the depression moves westward.  
In that case, the official intensity forecast could wind up being a 
little too high.  The NHC intensity forecast is well within the 
guidance envelope, but is a touch above the latest consensus.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/0300Z 12.5N 126.2W   25 KT  30 MPH
 12H  31/1200Z 12.4N 126.6W   30 KT  35 MPH
 24H  01/0000Z 12.3N 127.3W   30 KT  35 MPH
 36H  01/1200Z 12.4N 128.4W   35 KT  40 MPH
 48H  02/0000Z 12.7N 130.0W   35 KT  40 MPH
 60H  02/1200Z 13.1N 131.6W   35 KT  40 MPH
 72H  03/0000Z 13.4N 133.0W   40 KT  45 MPH
 96H  04/0000Z 13.8N 135.9W   45 KT  50 MPH
120H  05/0000Z 14.5N 138.9W   50 KT  60 MPH
 
$$
Forecaster Zelinsky
 
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