000
WTPZ41 KNHC 160233
TCDEP1

TROPICAL STORM KARINA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112014
800 PM PDT FRI AUG 15 2014

The convective pattern of Karina continues to deteriorate, with the
coverage of cold cloud tops decreasing during the past few hours.
The low-level center is partially exposed on the northeastern edge
of the convective canopy due to about 15 kt of easterly shear. A
blend of the latest Dvorak CI numbers from TAFB and SAB yields an
initial intensity estimate of 40 kt. Little change in strength is
expected during the forecast period. The vertical shear is expected
to decrease a little by day 3, but the cyclone will be moving over
somewhat cooler SSTs by then. The NHC intensity forecast is close to
the IVCN intensity consensus through the period.

The initial motion estimate is 280/09, as Karina is being steered
by a subtropical ridge to the north. This ridge will build westward
during the next couple of days, followed by an amplification of a
ridge well north of the Hawaiian Islands, which should result in
Karina's track bending a little south of due west during the middle
of the forecast period. By day 5, the ridging north of Karina will
weaken as a mid/upper-level trough amplifies off the west coast of
North America. This should result in a collapse of the steering
currents and a slow and perhaps erratic motion by the end of the
period. The NHC track forecast is largely an update of the previous
one and is close to the TVCE multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 17.8N 122.0W   40 KT  45 MPH
 12H  16/1200Z 18.1N 123.6W   40 KT  45 MPH
 24H  17/0000Z 18.2N 125.6W   40 KT  45 MPH
 36H  17/1200Z 18.1N 127.6W   40 KT  45 MPH
 48H  18/0000Z 17.8N 129.4W   40 KT  45 MPH
 72H  19/0000Z 17.2N 132.5W   45 KT  50 MPH
 96H  20/0000Z 17.0N 134.0W   45 KT  50 MPH
120H  21/0000Z 17.0N 134.5W   45 KT  50 MPH

$$
Forecaster Brennan