Tropical Storm FAUSTO

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TROPICAL STORM FAUSTO DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062014
800 PM PDT TUE JUL 08 2014

Visible satellite imagery indicates that the center of Fausto has
pulled northwestward away from the main convective cloud mass and
is now fully exposed in the middle of the larger scale cyclonic
gyre. The initial intensity has been decreased to 35 kt based on
satellite current intensity estimates of 35 kt and 39 kt from TAFB
and UW-CIMSS ADT, respectively.

The initial motion is 290/16 kt, which is a 12-hour average motion.
A recent northwestward jog in the track is believed to be a
temporary motion, and Fausto is expected to turn back toward the
west-northwest fairly soon. A strong ridge to the north of the
cyclone is expected to keep Fausto moving west-northwestward for the
for the next 72 hours. After that, the cyclone is expected to
weaken and become vertically shallow, being steered more westward
by the brisk low-level trade wind flow. The official forecast track
is a little to the right of and faster than the previous advisory,
mainly due to the more northward initial position, and is similar
to the consensus model TCVE.

Fausto is experiencing light deep-layer vertical wind shear of less
than 5 kt and the mid-level shear is only around 5 kt, so the sudden
development of an exposed low-level circulation is perplexing.
However, various water vapor products and microwave satellite
imagery suggest that dry mid-level air has intruded into the inner
core, disrupting the deep convection and allowing the low-level
vortex to briefly decouple from the mid- and upper-level
circulations. Further exacerbating these unfavorable conditions is
a large disturbance located about 800 nmi to the northeast of the
cyclone, which has been deflecting some of the southerly low-level
inflow away from Fausto and into that system. The global models
indicate that the shear will remain light for another 24 hours or
so, and that Fausto and the aforementioned disturbance will begin to
separate from each other in about 12 hours or so, which could allow
for some slight re-strengthening. By 72 hours and beyond, however,
northwesterly wind shear is forecast to increase to more than 30 kt,
inducing significant weakening while the cyclone also moves over
cooler water. The NHC intensity forecast is lower than the previous
advisory forecast, and closely follows the intensity consensus
models IVCN and ICON.

FORECAST POSITIONS AND MAX WINDS

INIT  09/0300Z 11.0N 126.5W   35 KT  40 MPH
 12H  09/1200Z 11.7N 128.8W   35 KT  40 MPH
 24H  10/0000Z 12.5N 131.7W   40 KT  45 MPH
 36H  10/1200Z 13.4N 134.9W   40 KT  45 MPH
 48H  11/0000Z 14.2N 137.6W   40 KT  45 MPH
 72H  12/0000Z 16.0N 142.8W   30 KT  35 MPH
 96H  13/0000Z 17.4N 146.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  14/0000Z 18.4N 150.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart

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