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Hurricane BARBARA


Hurricane Barbara Discussion Number  11
NWS National Hurricane Center Miami FL       EP022019
500 PM HST Tue Jul 02 2019

GOES-17 visible and infrared satellite images, along with passive
microwave satellite data, indicate that Barbara has continued to
rapidly intensify. A 15-nmi diameter clear eye with temperatures
warmer than 21 deg C has developed in the center of a circular CDO
feature consisting of cloud tops colder than -70 deg C. Satellite
intensity estimates have been vacillating between T6.8/135 kt from
UW-CIMSS ADT to T7.0/140 kt from TAFB, NHC objective-AODT, and CIMSS
SATCON. Since the T7.0/140-kt estimates have only been intermittent,
the intensity has been raised to a solid 135 kt, or just below the
category-5 threshold.

The initial motion estimate is 285/12 kt. There is no change to
previous forecast discussions. Barbara is forecast to remain south
of a pronounced deep-layer ridge throughout the forecast period,
resulting in west-northwestward to northwestward motion through 48
hours, followed by a turn toward the west by 72 hours when Barbara
is expected to be a rapidly weakening and vertically shallow
cyclone. The latest NHC track guidance is tightly packed around the
previous forecast track, so the new official forecast track is
essentially just an update and an extension of the previous advisory
track, and closely follows a blend of the consensus models HCCA,

Barbara has probably peaked in intensity, although another 5-kt
increase in strength tonight during the convective maximum period is
a distinct possibility, which would bring the powerful hurricane to
category 5 status. However, all of the available intensity guidance
is unanimous in indicating a weakening trend will begin in 12 hours
or so due to the development of cold upwelling beneath the
hurricane, coupled with a likely eyewall replacement cycle. The
26-deg-C SST isotherm lies east-west along 17N latitude, and Barbara
is forecast to move over much cooler waters by 48 hours, at which
time more prodigious cold upwelling beneath the cyclone is expected
to develop, causing a rapid weakening trend to ensue. Increasing
southwesterly to westerly vertical wind shear in excess of 20 kt is
forecast to develop by 96 hours, resulting in Barbara degenerating
into a post-tropical low by the time the cyclone moves west of 140W
longitude and into the central Pacific basin. The new NHC official
intensity forecast is similar to the previous advisory, and is a
little lower than the intensity consensus models HCCA and IVCN.

NOTE:  Beginning this hurricane season, all National Hurricane
Center eastern Pacific advisory products that utilize local time,
and the corresponding graphical products, will use Hawaiian Standard
Time (HST) instead of Pacific Daylight Time (PDT) or Standard Time
(PST) if the final forecast point is west of 140W.  Since Barbara's
day 5 official forecast point is now west of 140W, advisory products
are now being issued in Hawaiian Standard Time.


INIT  03/0300Z 13.1N 124.6W  135 KT 155 MPH
 12H  03/1200Z 13.7N 126.0W  130 KT 150 MPH
 24H  04/0000Z 14.7N 127.8W  120 KT 140 MPH
 36H  04/1200Z 15.9N 129.5W  105 KT 120 MPH
 48H  05/0000Z 17.1N 131.3W   90 KT 105 MPH
 72H  06/0000Z 18.9N 135.3W   60 KT  70 MPH
 96H  07/0000Z 19.2N 140.7W   35 KT  40 MPH...POST-TROPICAL
120H  08/0000Z 19.0N 147.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

Forecaster Stewart