AXPZ20 KNHC 010234
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sat Oct 1 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
Based on 0000 UTC surface analysis and satellite imagery through
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough axis extends from 10N85W to 10N92W to 12N105W.
It resumes at 12N116W to 09N123W to 10N130W to 08N140W. Scattered
moderate isolated strong convection is within 120 nm south of the
axis between 85W and 89W. Scattered moderate convection is within
120 nm north of the axis between 94W and 97W, and south of the
trough within 30 nm of 10N106W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
What earlier was a remnant low is now a trough 26N118W to
21N116W. The trough will slowly move west-southwest through Sunday
while losing its identity
A weak pressure gradient over the forecast waters is supporting
mainly light to gentle winds across the area. The pressure
gradient between high pressure ridging over central Mexico, and
a surface trough over the eastern Bay of Campeche again tightens
tonight. This will send another surge of strong northerly winds
through the isthmus of Tehuantepec, and through the Gulf late
tonight, and into Saturday morning with seas building to the range
of 8 to 10 ft. These strong winds will diminish Saturday
afternoon with seas subsiding to 8 ft in northeast swell, then
pulse back to strong intensity Saturday night, and diminish on
Sunday afternoon. The pulsing of these winds will continue into
early next week.
Seas are in the 4 to 6 ft range north of 20N outside the Gulf of
California, 6 to ft south of 20N, and 2 ft or less through all
but the southern entrance to the Gulf of California. As the
remnant low of Rosyln dissipates, high pressure will build across
the region from the northwest through the weekend and strengthen
the pressure gradient to the west of 110W. This will produce a
modest increase in winds across the Pacific waters of the Baja
California Peninsula. Associated northwest to north swell is
forecast by wavewatch model guidance to spread into the northeast
waters beginning early on Saturday, with seas of 6 to 8 ft. The
swell is expected to reach south to near 26N by Sunday evening
with max seas building to around 9 ft.
A surface trough is analyzed from 22N114W to low pressure near
17N114W 1011 mb to 13N113W. Scattered strong convection is
occurring within 120 nm east of the trough. Scattered moderate
isolated strong convection is within 150 nm west of the trough
and low from 17N to 22N, and from 17N to 19N between 110W and
112W. The trough will continue to move west-northwest through
Sunday with low chances for development.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Light and variable winds are expected north of the monsoon
trough, while gentle to locally moderate south to southwesterly
winds are expected south of the monsoon trough through the
upcoming weekend. Combined seas of 4 to 7 ft, primarily in long-
period southwesterly swell is expected across the offshore waters
through the upcoming weekend.
REMAINDER OF THE AREA...
High pressure will build over the northern waters which will
increase the pressure gradient, freshening winds north of the
monsoon trough this weekend. The long fetch of these fresh trades
will help build seas to the 7-9 ft range early next week.