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TROPICAL STORM CELIA DISCUSSION NUMBER  27
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042016
200 AM PDT WED JUL 13 2016

While Celia continues to show an eye in infrared imagery, several
recent microwave overpasses indicate this feature is displaced to
the north-northeast of the low-level center.  Satellite intensity
estimates from TAFB and SAB are 65 kt, and a recent CIMSS AMSU
estimate is 74 kt.  However, a partial ASCAT-B overpass showed
maximum winds of 55 kt north of the center.  Given these data and
the level of disorganization implied by the microwave imagery,
Celia is downgraded to a tropical storm with 60-kt winds.

The initial motion is 300/10.  A mid-level subtropical ridge is
predicted by the global models to remain to the north of the cyclone
for the next several days.  This should result in Celia moving
west-northwestward for the next 36-48 hours.  After that time, the
guidance becomes somewhat divergent.  The GFS and UKMET models are
on the south side of the guidance envelope and forecast a more
westward motion, while the ECMWF is on the north side and forecasts
a continued west-northwestward motion.  Overall, the consensus
models have shifted a little to the south after 36 hours.  Based on
this, the new forecast track is also shifted a little to the south
and shows a just north of due west motion from 48-120 hours.

Celia should encounter decreasing sea surface temperatures for the
next 48-72 hours.  After 72 hours, the cyclone is likely to
encounter strong westerly shear even as it moves over slightly
warmer water.  This evolution should cause Celia to weaken further,
with the system forecast to become a tropical depression by 72 hours
and a remnant low by 120 hours.  The new forecast intensity is an
update of the previous forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0900Z 18.3N 131.2W   60 KT  70 MPH
 12H  13/1800Z 19.3N 132.7W   55 KT  65 MPH
 24H  14/0600Z 20.4N 134.8W   50 KT  60 MPH
 36H  14/1800Z 21.3N 136.9W   40 KT  45 MPH
 48H  15/0600Z 22.0N 139.0W   35 KT  40 MPH
 72H  16/0600Z 22.5N 144.0W   30 KT  35 MPH
 96H  17/0600Z 23.0N 149.0W   25 KT  30 MPH
120H  18/0600Z 23.5N 153.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven

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