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Hurricane LESTER Forecast Discussion

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WTPZ43 KNHC 300852

200 AM PDT TUE AUG 30 2016

Lester has begun to weaken.  The areal extent of deep convection
within the hurricane's central dense overcast (CDO) has decreased
substantially, and the CDO has lost much of its axisymmetry since
late yesterday.  In addition, the eye has warmed and become a little
less defined. The recent weakening could be associated with an
increase in easterly shear over the cyclone as analyzed by UW-CIMSS
and SHIPS model output.  Dvorak T-numbers have responded by suddenly
decreasing.  A blend of the latest TAFB Final T- and CI-numbers,
including the UW-CIMSS ADT values, is used to lower the initial
intensity estimate to 110 kt.

The initial motion estimate is 275/12.  A strong mid-level ridge
over the east-central subtropical Pacific should continue to steer
Lester just north of due west for the next couple of days.  A
probable binary interaction with Madeline should cause Lester's
heading to turn west-northwestward as the hurricane approaches the
Hawaiian Islands in 3-5 days.  The NHC track forecast is barely
adjusted relative to the previous one, and is closest to a blend of
the GFS and ECMWF solutions.

The intensity forecast is, again, quite challenging. The delicate
balance of environmental factors leading to Lester's annular
structure yesterday may have been disrupted by the recent uptick in
easterly shear.  With the shear forecast to diminish over the next
day or so while the cyclone continues to move over nearly constant
SSTs, Lester could regain its annular characteristics.  This would
allow Lester to sustain a higher intensity during the next 2-3 days
than what the intensity guidance indicates.  After that time, the
ECMWF shows a less conducive environment than the GFS, which could
result in a more decided weakening.  Given the greater than normal
uncertainty, the NHC forecast stays close to the multi-model
consensus throughout the period.

Lester's wind radii have been adjusted based on a partial ASCAT


INIT  30/0900Z 18.2N 133.2W  110 KT 125 MPH
 12H  30/1800Z 18.3N 135.1W  100 KT 115 MPH
 24H  31/0600Z 18.4N 137.5W   90 KT 105 MPH
 36H  31/1800Z 18.4N 139.7W   90 KT 105 MPH
 48H  01/0600Z 18.5N 141.9W   85 KT 100 MPH
 72H  02/0600Z 19.3N 146.4W   80 KT  90 MPH
 96H  03/0600Z 20.8N 151.2W   70 KT  80 MPH
120H  04/0600Z 22.7N 156.4W   60 KT  70 MPH

Forecaster Kimberlain