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Hurricane ULIKA Forecast Discussion


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000
WTPZ44 KNHC 280853
TCDEP4

HURRICANE ULIKA DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP192016
200 AM PDT WED SEP 28 2016

Ulika has continued to improve in organization, and recent microwave
data have shown that the cyclone has maintained a well-defined eye
in the 89-GHz channel during the past few hours.  Hints of an eye
have also been observed in shortwave infrared imagery, embedded
within a compact central dense overcast.  Subjective satellite
intensity estimates have risen to T4.0/65 kt from TAFB and T3.0/55
kt from SAB, and the objective ADT from UW-CIMSS is even higher
around 75 kt.  A couple of CIMSS AMSU intensity estimates also
provided values of 60-65 kt several hours ago.  Based on these
data, Ulika is upgraded to a hurricane with 65-kt winds, and this
could be conservative.

Ulika has rapidly intensified during the past 24 hours, which in
hindsight was probably helped by the cyclone's small wind field and
radius of maximum winds.  Vertical shear is expected to remain low
for another 12 hours or so, which could allow Ulika to intensify
some more in the short term.  By 24 hours, however, southwesterly
to westerly vertical shear is forecast to increase markedly,
exceeding 30 kt in a couple of days.  Given Ulika's small size, the
cyclone will be particularly sensitive to the increase in shear,
and its intensity is likely to decrease quickly.  Ulika is expected
to become a remnant low by day 4 and then dissipate southeast of
the Hawaiian Islands by day 5.  The NHC intensity forecast is very
close to the intensity consensus for the entire forecast period, and
is higher than the previous forecast during the first 36 hours to
account for Ulika's recent intensification trend.

A mid- to upper-level low northwest of Ulika is steering the
hurricane north-northeastward, or 030/6 kt.  Ulika is expected to
turn northward and northwestward around this feature during the next
couple of days.  After it becomes a weaker system, it should then
come under greater influence from the low-level trades, turning
west-northwestward and westward on days 3 and 4.  With the
exception of the GFDL, which is well north of the rest of the
guidance suite, all of the track models are tightly clustered
during the forecast period.  The NHC track forecast is therefore
close to the various consensus aids and not too different from
the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 13.9N 139.0W   65 KT  75 MPH
 12H  28/1800Z 14.7N 138.9W   70 KT  80 MPH
 24H  29/0600Z 15.6N 139.1W   65 KT  75 MPH
 36H  29/1800Z 16.4N 139.6W   55 KT  65 MPH
 48H  30/0600Z 17.0N 140.6W   45 KT  50 MPH
 72H  01/0600Z 17.7N 143.3W   35 KT  40 MPH
 96H  02/0600Z 17.7N 147.3W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  03/0600Z...DISSIPATED

$$
Forecaster Berg