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Tropical Depression NINETEEN Forecast Discussion

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WTPZ44 KNHC 262031

200 PM PDT MON SEP 26 2016

The depression's cloud pattern is a little less organized than it
was earlier today.  Visible satellite imagery shows the low-level
center near the western edge of a small mass of deep convection
whose convective tops have warmed, presumably due to some
northwesterly shear. Dvorak satellite classifications are T2.0 and
T2.5 from SAB and TAFB, respectively.  The initial intensity
estimate is held at 30 kt, on the lower end of these values.

The large-scale factors influencing the intensity of the depression
over the next few days are less conducive than previously assessed.
Even though the cyclone will be moving over waters around 28 deg C
and will encounter an increasingly diffluent flow aloft, some west-
northwesterly shear is forecast to persist.  A marginally moist
environment surrounding the tropical cyclone is also forecast to
dry further.  The NHC intensity forecast is reduced some over the
previous one in line with the current guidance and much below the
dynamical guidance.  Once the cyclone gains enough latitude in 3 to
4 days, westerly shear of 30 to 40 kt is expected to reduce the
system to a remnant low.

The cyclone's heading has been more westerly than previously
estimated, and a longer-term average of satellite fixes yields an
initial motion estimate of 285/05.  Global models show the cyclone
turning abruptly northward within the next 24 hours and then north-
northeastward as it rotates around a mid-tropospheric cyclone slowly
retrograding near 18N 140W.  When the cyclone decouples in 3 to 4
days, a turn toward the west is likely as the remnant low is steered
by the low-level trade wind flow.  The new track forecast is shifted
toward the left of the previous track because of the more westerly
initial motion and lies well west of the multi-model consensus,
closest to the leftmost ECMWF model.

The next advisory will be issued issued by the Central Pacific
Hurricane Center.


INIT  26/2100Z 11.6N 140.4W   30 KT  35 MPH
 12H  27/0600Z 12.3N 140.3W   35 KT  40 MPH
 24H  27/1800Z 13.0N 140.0W   40 KT  45 MPH
 36H  28/0600Z 13.9N 139.3W   45 KT  50 MPH
 48H  28/1800Z 15.0N 139.1W   45 KT  50 MPH
 72H  29/1800Z 16.3N 139.5W   40 KT  45 MPH
 96H  30/1800Z 17.1N 141.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  01/1800Z 17.2N 144.4W   20 KT  25 MPH...POST-TROP/REMNT LOW

Forecaster Kimberlain