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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 302109

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Jul 30 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 1800 UTC surface analysis and satellite imagery through
2115 UTC.


An area of low pressure remains embedded within the monsoon
trough near 14N118W with an estimated minimum central pressure
of 1008 mb, moving west-northwest at around 10 kt. Scattered
moderate to strong convection was noted within 240 nm in the
south and southeast quadrants of the low. 1704 and 1756 UTC
ASCAT passes indicated S to SW winds of 20 to 25 kt have
developed within 240 nm in the SE semicircle of the low and
elsewhere from 07N to 11N between 115W and 120W. these winds
have been included in the latest High Seas Forecasts issued
under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC. Conditions are
forecast to become more conducive for development of this low
over the next few days, and it now has a high chance of tropical
cyclone formation through the next 48 hours.


A tropical wave is along 99W/100W from 10N to 16N and is moving
west at 10 to 15 kt. Associated convection is difficult to
differentiate from a nearby area of low pressure, while
additional convection behind the wave is convective activity
which developed over Central America last night and has
propagated offshore.


The monsoon trough axis extends from 08N78W to 11N95W to low
pressure near 08N102W to low pressure near 14N118W to 10N133W.
The intertropical convergence zone axis extends from 10N133W to
09N140W.  Scattered moderate convection was noted within 180 nm
south of the monsoon trough between 85W and 89W...and within 240
nm south of the monsoon trough and ITCZ west of 120W.


N of 15N E of 120W:

In the Gulf of California, surface troughing will linger along
the Baja California peninsula for the next few days. Moderate to
fresh south to southeasterly flow will prevail in the central and
northern Gulf on the east side of this troughing, with light and
variable winds across the southern Gulf. Winds in the central and
northern Gulf will diminish late in the weekend as the pressure
gradient relaxes.

Across the Gulf of Tehuantepec, nocturnal northerly flow increased
to fresh to strong in the immediate Gulf. Similar conditions are
expected again late tonight into early Sunday, and then slightly
stronger late Sunday night into early Monday. Seas will build to 8
ft again by early Sunday, then up to 8 to 10 ft by early Monday
with the stronger winds. The fresh to strong nocturnal drainage
flow will then persist each night through Wednesday night.

Elsewhere, A weak surface ridge extends into the area from the
northwest, partially disrupted by the remnant circulation of Frank
located well to the west. This ridging will support mainly gentle
west to northwest flow across the open Pacific waters,
occasionally pulsing to moderate just offshore of the Baja
California peninsula. Seas will remain in the 4 to 6 ft range.

S of 15N E of 120W: 

Across the Gulf of Papagayo, drainage flow has diminished.
Another pulse of fresh to strong flow is expected late tonight
into early Sunday, and then again late Sunday night into early
Monday. Weaker winds are expected through the middle of next
week as the monsoon trough drifts slightly northward.
Otherwise, light to moderate flow is anticipated on either side of
the monsoon trough.

Long-period cross-equatorial southwesterly swell producing seas
of 6 to 8 ft, will gradually decay through Sun. Broad and weak
1009 mb low pressure is near 08N102W with scattered moderate
convection within 240 nm in the north and 120 nm in the south
semicircles. The low is forecast to gradually weaken through the
next 48 hours, then may strengthen thereafter.

W of 120W:

Ridging extending from northwest of the area is disrupted by the
remnant 1011 mb circulation of Frank, currently near 24N128W. This
low remnant will become a trough later today or tonight.

Fresh to strong northerly winds offshore of California will
generate fresh northerly swells. Seas of 8 ft will propagate down
to 29N by late Sunday night into early Monday, decaying to less
than 8 ft by the middle of the week.