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HURRICANE CELIA DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042016
200 PM PDT MON JUL 11 2016

During the past 6 h, the inner-core region of Celia has undergone
multiple evolutions from a banding eye into a large eye that was
more representative of an annular hurricane to what has now become
a 20-nmi cloud-filled eye. Subjective Dvorak current intensity (CI)
estimates remain T4.5/77 kt from TAFB and SAB, and CIRA and CIMSS
AMSU objective intensity estimates were 87 kt and 86 kt at 1435Z,
respectively. Since those subjective and objective estimates were
obtained, the inner-core convection has increased markedly,
especially during the past few hours, with tightly coiled convective
bands now concentrated within mainly 70 nmi of the center. Based on
the improved satellite appearance, the initial intensity has been
increased to 85 kt.

The initial motion estimate is 280/08 kt. As anticipated, Celia has
slowed its forward motion as it approaches a developing weakness in
the subtropical ridge. A turn toward the west-northwest later
tonight is expected as Celia begins to move into the developing
weakness in the ridge. The shortwave trough that is inducing this
weakness is forecast to weaken in 48-72 h and lift out to the north
or northeast. This will allow the ridge to re-strengthen and
gradually nudge Celia back on a more westward track in the 72-120 h
period. The latest NHC track guidance continues to be in excellent
agreement with very little spread in the models, and the new
forecast track is essentially just an update of the previous
advisory track, and lies along the southern edge of the guidance
envelope.

The center of Celia is currently passing over 25.5 deg C SSTs based
on reports from drifting buoy 43540, which is about 2 deg C cooler
than the SHIPS intensity model is indicating. Having said that, the
cooler water doesn't appear to have negatively affected Celia today,
perhaps due to the proximity to warmer water and deeper instability
to the south. However, by 12 h and beyond, Celia will be moving over
a large field of sub-26 deg C SSTs and into an extensive region of
stable stratocumulus clouds, and the decreasing instability is
expected to induce steady weakening throughout the remainder of the
forecast period. However, with the vertical shear forecast to remain
low, Celia is expected to still be a tropical cyclone when it
crosses 140W longitude and moves into the Central Pacific basin in
84-96 h. The new intensity forecast is similar to the previous
advisory, and closely follows the consensus model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 15.2N 126.2W   85 KT 100 MPH
 12H  12/0600Z 15.7N 127.6W   85 KT 100 MPH
 24H  12/1800Z 16.6N 129.4W   80 KT  90 MPH
 36H  13/0600Z 17.7N 131.2W   70 KT  80 MPH
 48H  13/1800Z 18.8N 133.2W   60 KT  70 MPH
 72H  14/1800Z 20.5N 137.4W   50 KT  60 MPH
 96H  15/1800Z 21.3N 142.0W   40 KT  45 MPH
120H  16/1800Z 21.8N 147.2W   35 KT  40 MPH

$$
Forecaster Stewart

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