000
WTPA43 PHFO 050256
TCDCP3
 
Tropical Depression Twelve-C Discussion Number   3
NWS Central Pacific Hurricane Center Honolulu HI   EP122019
500 PM HST Wed Sep 04 2019
 
Tropical Depression 12E is quite a mess late this afternoon, and
there remains considerable uncertainty in the initial position. A
couple of low level centers have been identified over the past few
hours in the visible satellite imagery, and for now we have chosen
to follow the one nearer to, and just north of, a burst of deep
convection. This is in agreement with satellite fixes from PHFO and
JTWC. Subjective intensity estimates were 1.0 or 1.5 from all fix 
agencies, so will maintain 25 kt as the initial intensity. The 
overall circulation is still rather elongated and asymmetric, 
embedded in a larger monsoon trough. 

Best guess at the initial motion is 250/6, based on the movement of 
the cloud system center. The shallow circulation associated with
the depression continues to be steered by the trade wind flow.
There's a fairly large spread in the guidance as early as 24-36
hours, likely due in part to the uncertainties in initial location
and movement. However, the general idea is that as the convection
slowly organizes, a more westward motion is expected by about 36
hours, followed by a turn toward the west-northwest and an increase
in forward speed. The operational GFS appears to be an outlier in
the guidance, showing a slower forward motion and a bit of a
sharper turn due to a weaker subtropical ridge north of the cyclone
beyond 72 hours. Our forecast is similar to the previous package,
which remains closer to the consensus guidance and the ECMWF
ensemble mean.

It remains to be seen whether or not 12E can get organized and
break free of the monsoon trough. There may also be some dry air
impinging on the north semicircle of the cyclone. Otherwise,
conditions appear to be relatively favorable for development, with
sea surface temperatures over 28C along the forecast track, and weak
shear for at least the first 72 hours. Our intensity forecast
assumes that 12E can overcome these inhibiting factors and gradually
strengthen, in good agreement with the SHIPS and ICON intensity
guidance. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0300Z 12.1N 141.4W   25 KT  30 MPH
 12H  05/1200Z 11.8N 142.4W   30 KT  35 MPH
 24H  06/0000Z 11.5N 143.9W   30 KT  35 MPH
 36H  06/1200Z 11.5N 145.2W   35 KT  40 MPH
 48H  07/0000Z 11.7N 146.8W   40 KT  45 MPH
 72H  08/0000Z 12.5N 151.0W   50 KT  60 MPH
 96H  09/0000Z 14.2N 156.8W   55 KT  65 MPH
120H  10/0000Z 16.1N 162.6W   55 KT  65 MPH
 
$$
Forecaster R Ballard