AXPZ20 KNHC 231515
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Sat Sep 23 2017
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 broad elongated area of low pressure remains in place along
the southwestern coast of Mexico and adjacent coastal waters,
from Cabo Corrientes to near Acapulco. Satellite imagery shows a
weak low center near 18N105W with an estimated pressure of 1005
mb. Scatterometer data shows fresh to strong W-SW monsoon winds
along 10N-13N S and SW of the low center are detached from the
low, and monsoonal flow is bypassing it to the south instead of
feeding into the circulation, as was the case the past few days.
Model guidance indicates that the low has potential to develop
into a tropical cyclone as it drifts NW toward the southern Gulf
of California. The convergent monsoonal winds will continue to
generate widespread active convection along and near the coast
of Mexico and Central America for several more days.
..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough stretches across most of the basin from
northern Colombia near 10N74W across Panama to 09N85W through
low pres near 13N91W to 15N97W to 14N101W, then resumes from
14N108W to low pres near 13N136W. Scattered moderate isolated
strong convection is found along and up to 180 nm SW of the
trough axis between 90W and 97W, and from 10N to 12N between
130W and 136W. Scattered moderate convection is present within
90 nm s of the trough axis between 109W and 119W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
A dissipating cold front extends from SE Arizona SW across the
Gulf of California and Baja California to 21N118W. Expect the
front to dissipate by this evening. High pressure building north
of 25N behind the front will help increase NW winds west of Baja
California Norte through Sun. Elsewhere, expected development of
low pressure along the coast of Mexico near Cabo Corrientes will
increase winds and seas north of Cabo Corrientes to the southern
Gulf of California during the next few days.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
An active monsoon trough near the coast of Central America from
Guatemala to Panama will remain the focus for active convection
in coastal waters the next few days. Expect SW winds south of
the trough remain moderate to fresh this weekend. Farther south,
gentle to moderate south to southwest winds will persist south
of 05N through Monday. Long period SE swell from the Southern
Hemisphere will maintain seas west of Ecuador and south of the
Equator around 7 ft through Sunday.
REMAINDER OF THE AREA...
NW swell generated by strong winds north of the area producing 7-
8 ft seas N of 30N between 116W and 123W. Low pres near 13N137W
will move west of the discussion area Sunday. High pres centered
well N of the area and low pressure associated with the monsoon
trough will maintain moderate to occasionally fresh trade winds
W of 120W through Mon. Low pres passing north of the area will
weaken the high, allowing trades to decrease later in the week.