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Tropical Depression TWELVE-E

Tropical Depression Twelve-E Discussion Number   4
NWS Central Pacific Hurricane Center Honolulu HI   EP122019
1100 PM HST Wed Sep 04 2019
Latest conventional and microwave satellite images show that the 
depression's organization has changed little over the past 6 hours, 
with a somewhat elongated center producing spotty deep convection. 
Latest subjective Dvorak intensity estimates from PHFO/PGTW/SAB 
support maintaining an initial intensity of 25 kt for this advisory.

The initial motion estimate for this advisory is an uncertain 260/7 
kt, with the depression primarily being steered by a low-level
ridge far to the north. The forecast anticipates that the depression
will move generally west to west-northwest through the forecast
period. An increase in forward speed is expected after day 3 as the
cyclone moves south of a strengthening deep-layer ridge centered far
north of the main Hawaiian Islands. Guidance continues to show a
large spread beginning as early as 24-36 hours, likely due in part
to the uncertainties in initial location and movement. The GFS/HWRF
are outliers on the right hand side of the guidance envelope, with
the other reliable models clustered farther to the south. The
updated official forecast has been nudged southward of the previous,
and represents a blend between the HCCA and ECMWF. 

Model guidance continues to indicate that the cyclone will be slow
to organize, despite sufficiently warm SSTs and relatively low
vertical wind shear along the forecast track. Dry air impinging on
the circulation from the north may be an inhibiting factor, as well
as the poorly organized initial structure. The updated intensity 
forecast has changed little from the previous, is close to the
SHIPS and IVCN consensus, and anticipates that the cyclone will
eventually become better organized. However, increasing vertical
wind shear in the later periods may preclude strengthening to a
INIT  05/0900Z 12.0N 142.3W   25 KT  30 MPH
 12H  05/1800Z 11.9N 143.3W   30 KT  35 MPH
 24H  06/0600Z 11.7N 144.9W   35 KT  40 MPH
 36H  06/1800Z 11.6N 146.3W   40 KT  45 MPH
 48H  07/0600Z 11.7N 148.0W   45 KT  50 MPH
 72H  08/0600Z 12.7N 152.7W   50 KT  60 MPH
 96H  09/0600Z 14.0N 158.5W   55 KT  65 MPH
120H  10/0600Z 15.5N 165.0W   55 KT  65 MPH
Forecaster Birchard