Tropical Storm FAUSTO

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TROPICAL STORM FAUSTO SPECIAL DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062014
330 PM PDT MON JUL 07 2014

The area of low pressure located about 1000 nmi southwest of the
southern tip of Baja California has acquired enough organized
convection near the well-defined low-level circulation center to be
classified as a tropical cyclone. Although convection has been
waxing and waning over the past 12 hours or so, a new burst of deep
convection with cloud tops as cold as -83C have developed near and
just south of the center. The system is being designated as
Tropical Storm Fausto based on wind data from two earlier ASCAT
passes at 1704 UTC and 1757 UTC that indicated reliable wind speed
of 35-38 kt in the southeastern quadrant. Upper-level outflow is
good and continues to expand in all quadrants.

The initial motion estimate is 275/11 kt and is based primarily on
microwave satellite data. Fausto is expected to move westward for
the next day or so and then turn toward the west-northwest after
that as the cyclone moves along the southern periphery of a
deep-layer subtropical ridge to its north. By Days 4 and 5, a
weakness is forecast by all of the global models to develop between
140W-150W longitude, which should allow Fausto to turn more toward
the northwest. Although some of the models show the cyclone turning
into the ridge and beginning to recurve, the official forecast only
shows a slight stair-step in the track since the GFS and ECMWF
models show the ridge building back westward at the end of the Day 5
period. The official advisory track is a blend of the GFS and ECMWF
models since they have a better depiction of the small tropical
cyclone.

Fausto is expected to remain in a favorable environment consisting
of low vertical wind shear, a moist mid-level regime, and over
sea-surface temperatures in excess of 28C for at least the next 72
hours. These conditions should allow for at least some gradual
strengthening to occur, and the official forecast closely follows a
blend of the GFS-based SHIPS and LGEM models. However, those
intensity forecasts are based on the medium BAM model, which takes
the cyclone well north of the official forecast track and into
strong shear conditions and over colder water by Days 4 and 5. If
Fausto fallows a low-latitude track as indicated by the NHC
forecast, then strengthening rather than weakening could occur in
the latter periods.

FORECAST POSITIONS AND MAX WINDS

INIT  07/2230Z  9.5N 120.1W   35 KT  40 MPH
 12H  08/0600Z  9.7N 121.5W   40 KT  45 MPH
 24H  08/1800Z 10.0N 124.1W   45 KT  50 MPH
 36H  09/0600Z 10.7N 127.0W   50 KT  60 MPH
 48H  09/1800Z 11.5N 130.4W   55 KT  65 MPH
 72H  10/1800Z 12.6N 136.0W   55 KT  65 MPH
 96H  11/1800Z 14.7N 140.9W   45 KT  50 MPH
120H  12/1800Z 16.0N 146.0W   35 KT  40 MPH

$$
Forecaster Stewart

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