000
AXPZ20 KNHC 270945
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Sep 27 2016

Tropical weather discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
0945 UTC.

...SPECIAL FEATURES...

Tropical Storm Roslyn centered at 17.8N 117.7W at 27/0900Z, or
about 615 sm wsw of the southern tip of the Baja California
Peninsula, moving ne, or 050 degrees at 6 kt. The estimated
minimum central pressure is 1003 mb. Maximum sustained wind
speed is 40 kt with gusts to 50 kt. Currently, scattered
moderate isolated strong convection is observed within 240 nm
over the ne quadrant of the center. Roslyn is forecast to weaken
to a tropical depression tonight, and further weaken to a
remnant low late Wed, and gradually dissipate on Thu. Refer to
the latest NHC forecast/advisory under AWIPS/WMO headers WTPZ23
KNHC/TCMEP3, or visit the NHC website at http://hurricanes.gov
for additional details.

Tropical Storm Ulika is centered just w of the area at 12.1N
140.4W at 27/0900Z, or about 1105 sm ese of Hilo hawaii, moving
n, or 350 degrees at 3 kt. The estimated minimum central
pressure is 1004 mb. Maximum sustained wind speed is 35 kt with
gusts to 45 kt. Numerous strong convection is currently flaring
within 30 nm of the center, surrounded by scattered moderate
isolated strong convection elsewhere within 180 nm e and 60 nm w
semicircles of the center. Ulika is forecast to move ne and back
into the discussion area today. When the center is w of 140W,
refer to the latest CPHC forecast/advisory under AWIPS/WMO
headers WTPA22 PHFO/TCMCP2, or visit the CPHC website at
http:www.prh.noaa.gov/cphc/ for additional details.  After the
center moves e of 140W, refer to the latest NHC
forecast/advisory under AWIPS/WMO headers WTPZ24KNHC/TCMEP4,or
visit the NHC website at http://hurricanes.gov for additional
details.  

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends w off the Pacific coast of Costa Rica
at 09N78W to 10N86W, then dips sw to 12N97W to 09N112W where it
loses identity. Scatterometer winds indicate that the monsoon
trough resumes just sw of T.S. Roslyn at 13N120W to 12N138W.
Isolated moderate to strong convection is observed within
150 nm either side of a line 05N77W to 07N85W to 12N101W to 
08N114W.  120 nm either side of a line from 12N126W to 13N136W. 

Scattered moderate isolated strong convection is observed
within 75 nm either side of a line from 11N87W to 13N90W, 
within 75 nm either side of a line from 14N94W to 12N98W,
and within 30 nm either side of a line from 15N98W to 17N103W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A sub-tropical ridge axis extends from nw to se across the
offshore zones w of the Baja Peninsula terminating near 24N112W.
Light to gentle n-ne winds are observed w of the Baja Peninsula
with little change expected through Wed. 

Scattered convection, strong e winds and combined seas of 7 to
11 ft will expand ne across the waters generally from 18N to 23N
w of 114.5W through Wed as tropical cyclone Roslyn continues
northward. The subtropical ridge will extend from 29N120W to
20N106W on Fri with gentle n flow returning.  The pressure
gradient will tighten this weekend with moderate to fresh nw
winds, and 5 to 8 ft seas, w of Baja on Sun.

Light to gentle nw winds are expected across the entire Gulf of
California late today with little change expected through Thu.
Light and variable winds expected on Fri across the far northern
gulf waters.

Strong drainage flow expected across the Gulf of Tehuantepec
beginning Wed night, and then pulsing through the upcoming
weekend. 

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Light to gentle southerly winds expected n of the monsoon
trough, while gentle to locally moderate s to sw flow is
expected s of the monsoon trough through the upcoming weekend.
Combined seas of 3 to 6 ft primarily in long-period sw swell is
expected this week.

REMAINDER OF THE AREA... 

A cold front moving southeast out of the north central Pacific
will weaken the subtropical ridge to the north of the region for
the next couple of days. This will maintain gentle to moderate
northeast winds across most of the region outside of areas of
tropical cyclone activity and north of the monsoon trough with 5
to 6 ft seas. Moderate to occasionally fresh southerly flow will
dominate south of the monsoon trough with 6 to 7 ft seas.  

$$
Nelson