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TROPICAL STORM CELIA DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042016
200 AM PDT SUN JUL 10 2016

The intensity analysis of Celia is complicated tonight.  The
satellite presentation shows a small CDO feature near the center and
convective banding to the east and south of the center, which
supports Dvorak estimates of T3.5/55 kt from TAFB and SAB.  However,
a pair of ASCAT-A and ASCAT-B passes between 0445Z and 0535Z showed
winds of only 35-40 kt.  In addition, recent microwave imagery shows
that the inner core is not very organized yet, especially in the low
levels.  Given the ASCAT data, the initial intensity has been
conservatively lowered to 50 kt for this advisory.  The ASCAT data
were also used to adjust the initial 34-kt wind radii.

Celia is still expected to strengthen during the next couple of days
and become a hurricane, as the cyclone moves over SSTs of 27-28C.
Beyond 48 hours, the SSTs cool along the forecast track, which has
been adjusted a bit to the north of the previous advisory.  This
track takes Celia over SSTs below 26C by day 3 and over SSTs around
24C at days 4 and 5, which should result in weakening.  The new NHC
intensity forecast is lower than the previous one, but is above
all the guidance through 48 hours out of respect to continuity.
Late in the period the official forecast was also adjusted lower,
but is still above the intensity consensus.

Microwave imagery and the above-mentioned ASCAT data indicate that
Celia is located a bit north of previous estimates with an initial
motion of 280/10.  Celia is expected to move westward for the next
24 hours to the south of a mid-level ridge.  By 48 hours the cyclone
should turn west-northwestward as a weakness develops in the ridge
around 130W.  The ridge begins to rebuild back to the north of the
cyclone at 120 h, which should cause Celia to turn back toward the
west.  The new NHC track forecast is north of the previous one
through the forecast period, mainly due to the more northerly
initial position of the system.  This track is close to a blend of
the GFS and ECMWF models and is near the middle of the guidance
envelope.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 14.8N 119.8W   50 KT  60 MPH
 12H  10/1800Z 14.9N 121.5W   60 KT  70 MPH
 24H  11/0600Z 15.0N 124.0W   70 KT  80 MPH
 36H  11/1800Z 15.1N 126.3W   75 KT  85 MPH
 48H  12/0600Z 15.6N 128.2W   80 KT  90 MPH
 72H  13/0600Z 17.5N 131.7W   75 KT  85 MPH
 96H  14/0600Z 19.7N 135.3W   60 KT  70 MPH
120H  15/0600Z 21.0N 139.5W   50 KT  60 MPH

$$
Forecaster Brennan

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