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TROPICAL STORM NORA DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182015
800 PM PDT FRI OCT 09 2015

Deep convection has increased a little since the last advisory,
with the center located on the southeastern edge of the convective
mass due to light/moderate southeasterly shear over the cyclone.
The initial intensity is set to 35 kt based on the latest Dvorak
classifications from TAFB and SAB, marking the formation of
Tropical Storm Nora, the 14th tropical storm of the eastern North
Pacific season.  Environmental conditions appear favorable for
continued steady strengthening for the next 72 hours, with the
cyclone moving over SSTs at or above 29C during that period and
light shear. By days 4 and 5 the SHIPS model and global model fields
show the shear increasing, which should result in weakening. The
new NHC forecast is largely an update of the previous one, and is
close to or a little above the SHIPS model through the period.

The initial motion estimate is 275/14, as Nora is being steered
quickly westward by a subtropical ridge to the north. A gradual
decrease in forward speed is forecast during the next 36 hours as
the ridge slowly weakens, and Nora should then turn west-
northwestward as a weakness develops around 145W. Nora is then
forecast to recurve between a deep-layer trough over the north-
central Pacific and a strengthening ridge to the southeast by the
end of the period. The track model guidance is in overall good
agreement on this scenario, and the new NHC forecast is close to a
blend of the GFS and ECMWF models through the period. The new
official forecast is a little north of the previous one through 48
hours, and then is a little to the left, showing a more gradual
recurvature following the latest trend in the guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0300Z 11.3N 135.1W   35 KT  40 MPH
 12H  10/1200Z 11.6N 137.0W   40 KT  45 MPH
 24H  11/0000Z 11.8N 139.5W   50 KT  60 MPH
 36H  11/1200Z 11.9N 141.6W   60 KT  70 MPH
 48H  12/0000Z 12.3N 143.1W   65 KT  75 MPH
 72H  13/0000Z 13.0N 145.0W   80 KT  90 MPH
 96H  14/0000Z 15.0N 145.0W   75 KT  85 MPH
120H  15/0000Z 18.5N 142.5W   65 KT  75 MPH

$$
Forecaster Brennan

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