AXPZ20 KNHC 241631
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Aug 24 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 1200 UTC surface analysis and satellite imagery through
A 1007 mb low pressure center is near 14.5N108.5W, moving west-
northwest near 15 knots. The low pressure center has developed
from a tropical wave moving through that area, where a broad low
level easterly wind surge continues to produce scattered to
locally numerous moderate to strong convection within 300 nm
across the NE and 150 nm across the SW semicircles. 20-25 kt
easterly winds are assumed to be occurring at the surface
within this 300 nm NE semicircle, where seas are running 7-9 ft.
Satellite imagery continues to show improving organization of
this system with a well defined middle level circulation
evident. Environmental conditions are conducive for this system
to develop into a tropical cyclone later today through Thursday.
A gale warning has been issued for this system for Friday
morning in anticipation that these winds will be realized within
48 hours, as indicated by the majority of the global models.
A large and complex tropical wave is along about 126W, moving
westward at 10 to 15 knots. The associated moisture and
convection spans the area along the monsoon trough between 120W
and 130W. An elongated 1007 mb surface low has become better
defined during the past 12 hours, and is located near 11N122W.
Scattered to locally numerous moderate to strong convection is
occurring from 09N to 13N between 121.5W and 127W. A broad zone
of fresh easterly trade winds prevails north of the low from
about 13N to 17N between 118W and 129W, where seas are running 6-
8 ft. Environmental conditions are conducive for a gradual
improvement in organization of this system, and it has a medium
chance for tropical cyclone development within the next 48
hours. However, global models suggest a tropical cyclone may
develop by this weekend as the low moves west to west-
A tropical wave previously analyzed along 100W has moved NW
overnight and this morning and inland across southern and south
central Mexico. Associated low and middle level clouds and
convection occurring behind this wave have spread across the
Mexico City area to as far north as Tampico and interior
portions to the west.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends from low pre near 09N75W to 10N81W to
07N93.5W to low pres near 14.5N108.5W to low pres near 11N122W
to 10N138W, where it transitions to ITCZ, continuing on to
beyond 10N140W. Widely scattered to scattered moderate to strong
convection is occurring within 90 nm N and 150 nm S of the
trough E of 102W, and within 150 nm either side of the trough
between 116W and 131W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
A narrow surface ridge extends from the NE Pacific southeastward
through 30n125w to near Las Islas Tres Marias. This ridge will
change little during the upcoming weekend, and combine with the
persistent trough meandering along the Baja California peninsula
and Gulf of California to produce mainly light to moderate
northerly flow prevailing outside of the Gulf of California.
Expect mainly light to gentle southerly flow In the Gulf of
California, except for occasionally fresh wind flow in the
northern Gulf where the pressure gradient will be slightly
Very active convection associated with the tropical wave and low
pressure center near 14.5N108.5W is slowly moving away from the
southwest coast and coastal waters of Mexico. However, lines and
bands of moderate to strong convection described above were
still within 75 nm of the coast of Mexico offshore of
Manzanillo. East to northeast winds of 15-20 kt occurring across
the waters this morning will gradually diminish this afternoon
and evening and become light and variable as a weak ridge builds
across the area behind the exiting tropical wave.
High pressure across the Gulf of Mexico continues to drive
northerly winds across the Gulf of Tehuantepec, which had
increased to 25-30 kt early this morning, with seas 6-9 ft.
these winds will diminish today to 20-25 kt in a narrow plume,
and increase slightly again late tonight before diminishing to
15-20 kt by Friday.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Moderate to locally fresh offshore winds are expected across
mostof the area e of 95W and north of the monsoon trough today,
with strongest winds 15-20 kt across the Gulf of Papagayo
region. Winds are expected to become light and variable late
Thursday into Friday, except for 15-20 kt offshore winds across
Papagayo, then become onshore at 10 kt or less over the weekend.
The weak center center of the post-tropical remnant low of Kay
is a 1014 mb low pressure center near 24N123.5W. No deep
convective precipitation is present with the low pressure
center. The remnant low will continue to move west-
southwestward, and gradually dissipate into an open trough.
A broad area of 20 kt NE winds with seas 6-8 ft in found within
120 nm across the NW semicircle of the low.
A broad high pressure ridge dominates the remainder of the area,
extending from a large 1037 mb high across the NE Pacific. As
the low center along 122W and associated tropical wave move
westward during the next few days, the pressure gradient between
the monsoon trough and the ridge will yield freshening winds
across the trade wind belt, generally south of 21N, from just
northeast of the low center to beyond 140W. Seas of 6-8 ft in
this area in mixed swell will increase slightly to 7-9 ft during
this time. South of the monsoon trough, a large area of fresh
southwesterly monsoonal flow is supporting seas of 8 to 9 ft
north of 07N between 115W and 125W. The strength and areal
coverage of these fresh winds will increase south and southeast
of the low as it shifts westward over the next few days, and act
to increase seas to 6-8 ft in mixed south and southwest swell.