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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 181602

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri Oct 18 2019

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 1200 UTC surface analysis and satellite imagery through
1545 UTC.


Tropical Storm Octave is centered near 9.9N 127.1W at 18/1500 
UTC moving N at 2 kt. Estimated minimum central pressure is 1005
mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. 
Satellite imagery from during the morning shows that the earlier
convection that was noted has diminished significantly. The
latest GOES-17 imagery depicts scattered moderate convection
within 60 nm of the center in the western semicircle. Similar
convection in small clusters is within 30 nm of a line from 
10N125W to 12N126W, and within 30 nm of 10N130W and 09N131W.
Octave is forecast to linger over the general vicinity the next 
several days. Octave is now moving in a northward direction. 
It is expected to meander or make a gradual clockwise loop during 
the next few days, and it is forecast to weakened into a remnant
low over the weekend. See latest NHC forecast/advisory under 
AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for more details.


The axis of a tropical wave is near 83W, N of 02N, moving W at 
10-15 kt. Scattered moderate convection is noted from 03N to 08N
between 80W and 83W. 


The monsoon trough axis extends from northwest Colombia westward 
to across southern Costa Rica and to 10N86W, then northwestward
to 15N95W and westward to 15N105W to low pressure near 15N113W
and to 10N124W. It resumes to the west of Tropical Storm Octave
near 10N130W and to 10N140W. Scattered moderate to isolated 
strong convection is seen within 150 nm south of the trough
between 96W and 101W, and within 120 nm south of the trough 
between 135W and 139W. Scattered moderate convection is within 
150 nm south of the trough between 101W and 112W, within 120 nm 
southeast and south of the trough between 112W and 115W and also
between 132W and 135W.


Moderate to fresh southwesterly monsoonal flow will
continue in the Gulf of Tehuantepec zone and vicinity waters
through Sat. A set of large northwest to north swell propagating
across the Baja California Norte offshore waters will spread
southeastward reaching the Revillagigedo Islands by Sat night. 
Fresh to strong northwest to north winds will continue across 
the offshore zones of Baja California Norte through the weekend. 
Moderate to fresh northwest winds will develop in the northern 
and central Gulf of California Sun night and continue through
Tue night. Strong to near gale force north winds will develop in
the Gulf of Tehuantepec beginning late Tue night. Expect wave
heights there to build to large values late Tue night. 

A lingering low pressure of 1010 mb is located near 19N105W. The
CIRA LPW surface to 850 mb animation imagery confirms the small 
cyclonic with this low. Satellite imagery shows scattered 
moderate to isolated strong convection from 18N to 21N between 
105W and 109W. This low is forecast to drift south-southeastward 
and dissipate late Sun night or by early Mon afternoon.

Low pressure well to the southwest of the Mexican coast will
approach the west-central coast of Mexico by late Sun. This is 
expected to enhance present moist and unstable atmospheric 
conditions over these waters leading to additional shower and 
thunderstorm activity. Some of this activity may contain locally
heavy rainfall and strong gusty winds. 


Moderate to occassionally fresh southwest to west winds will 
change little through Sat night, then be at fresh to moderate 
speeds through early next week, except for winds diminishing to 
gentle speeds north of about 06N late Mon. Southwest will 
propagate into the waters between the Galapagos and Colombia 
tonight, then spread northward across the remainder of the 
forecast waters through the weekend. Wave heights will begin to 
subside early next week. 


Please read the Special Features section for more details about 
Tropical Storm Octave.

A 1010 mb low pressure is embedded in the monsoon trough near 
15N113W. This low is forecast to drift northeastward and 
weaken to a trough as it approaches the west-central coast 
of Mexico by late on Sun. 

A large set of northwest swell is propagating into the northern 
waters with wave heights above 8 ft to the northwest of a line 
from 32N115W to 21N140W. An overnight altimeter pass indicates 
seas near 13 ft near 29N133W. This swell will continue to 
propagate southeastward, with wave heights in the range of 11-14 
ft north of about 29N and between 120W and 123W tonight into Sat,
aided by fresh to strong winds which have spread southward from 
off the southern California coast. The edge of wave heights of 
8 ft or greater will reach to 10N and west of 110W by Sat night 
into Sun. This swell will gradually decay early next week.

Otherwise, a ridge extends across the waters N of 20N. Overnight
scatterometer data indicates mainly moderate to fresh winds N of
20N and gentle to moderate trades between the monsoon trough and
20N. Outside the northwest swell, wave heights are in the 5-7 ft