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Hurricane Barbara Discussion Number  16
NWS National Hurricane Center Miami FL       EP022019
1100 PM HST Wed Jul 03 2019

Barbara is on a weakening trend.  Although the hurricane is still
impressive in satellite images with a well-defined eye and
relatively symmetric convective pattern, the cloud tops have been
gradually warming in the eyewall.  Accordingly, the subjective and
objective satellite intensity estimates have been falling, and the
initial intensity is lowered to 105 kt.  This intensity estimate is
in best agreement with the Dvorak CI-numbers from TAFB and SAB.

The hurricane is still in relatively favorable conditions of
marginally warm waters, low wind shear, and a fairly moist
environment.  However, these conditions are expected to change
significantly during the next couple of days.  Barbara is forecast
to cross the 26 degree C isotherm in about 12 hours, and it will
also be moving into a progressively drier airmass during the next
day or two.  These conditions combined with a notable increase in
southwesterly shear suggest that rapid weakening is likely.  Barbara
is forecast to weaken to a tropical storm by 36 hours and
degenerate to a post-tropical cyclone by day 3.  The post-tropical
transition will likely occur around the time the cyclone enters the
Central Pacific basin, when Barbara is forecast to be over 25 degree
C waters and in an environment of about 30 kt of southwesterly
shear. The NHC intensity forecast lies near the various intensity
consensus models.

Barbara is moving west-northwestward at 10 kt steered by a mid-level
ridge to its northeast.  The hurricane is forecast to make a slight
turn to the northwest soon, and it should continue in that general
direction during the next day or so while it moves along the
southwestern periphery of the ridge.  After that time, low- to
mid-level ridging is expected to build to the north of the
weakening cyclone and that should cause it to move westward at a
faster pace.  The remnants of Barbara are expected to approach the
Hawaiian Islands in about 5 days.  The track models are tightly
clustered, and only small changes were made to the previous NHC
track forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0900Z 15.4N 129.2W  105 KT 120 MPH
 12H  04/1800Z 16.3N 130.4W   95 KT 110 MPH
 24H  05/0600Z 17.6N 132.1W   75 KT  85 MPH
 36H  05/1800Z 18.6N 134.0W   60 KT  70 MPH
 48H  06/0600Z 19.1N 136.3W   45 KT  50 MPH
 72H  07/0600Z 19.1N 142.1W   35 KT  40 MPH...POST-TROPICAL
 96H  08/0600Z 18.7N 148.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  09/0600Z 18.5N 155.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi

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