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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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