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TROPICAL STORM CELIA DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042016
800 AM PDT SUN JUL 10 2016

The satellite presentation of Celia has improved significantly since
the previous advisory, and a large, well-developed CDO feature is
now evident with overshooting cold tops of -80C to -85C having
developed near the center. The upper-level outflow pattern has also
improved and become more symmetrical. Satellite intensity estimates
range from T4.0/65 kt from TAFB and SAB to 61 kt from UW-CIMSS ADT
and a 1020Z AMSU intensity of 64 kt, putting Celia right at the cusp
of hurricane strength. The initial intensity is being held just
below hurricane status at 60 kt based on the e-w elongation of the
inner-core convection noted in the AMSU data.

The initial motion estimate is 275/12 kt. There is no significant
change to the previous forecast track or reasoning. Celia is
forecast to move westward for the next 24 h or so to the south of a
strong deep-layer subtropical ridge. By 36-48 h, Celia is expected
to turn west-northwestward as a shortwave trough currently located
along 130W longitude moves eastward and weakens the ridge. By day 3,
the trough is forecast to weaken and lift out to the north, allowing
the ridge to re-strengthen and turn Celia back to a more westward
motion. The new official forecast track is essentially just an
update of the previous advisory and lies close to the TCVE
multi-model consensus.

Based on the overall improvement in the infrared satellite pattern,
it appears that Celia is finally making the long-anticipated move
toward more significant intensification. The best conditions for
strengthening are expected to be during the next 24 h or so when
SSTs are at or above 27C and the vertical shear remains low at 5 kt
or less. By 36-48 h, cooling SSTs ahead of Celia are expected to
inhibit the strengthening process, resulting in a leveling off of
the intensity forecast. By 72 h and beyond, ocean temperatures will
be cooling down to 24C-25C, but the vertical shear is forecast to
remain low. As a result, slower than normal weakening is forecast on
days 3-5. The official intensity forecast is slightly higher than
the intensity consensus model IVCN, and closely follows a blend of
the SHIPS and LGEM statistical-dynamical models intensity forecasts.

FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 14.8N 121.3W   60 KT  70 MPH
 12H  11/0000Z 14.9N 123.1W   70 KT  80 MPH
 24H  11/1200Z 15.0N 125.5W   80 KT  90 MPH
 36H  12/0000Z 15.3N 127.6W   85 KT 100 MPH
 48H  12/1200Z 15.9N 129.4W   85 KT 100 MPH
 72H  13/1200Z 17.9N 132.9W   75 KT  85 MPH
 96H  14/1200Z 20.0N 136.6W   60 KT  70 MPH
120H  15/1200Z 21.0N 140.5W   55 KT  65 MPH

$$
Forecaster Stewart

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