Tropical Weather Discussion
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AXPZ20 KNHC 152145

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2048 UTC Mon Jul 15 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.


A tropical wave with axis along 89W from 04N to Honduras is
moving westward at 15 kt. Visible satellite imagery continues to
show a mid-level cyclonic circulation slightly ahead of wave
axis. Convection has waned this afternoon, but scattered moderate
convection is occurring from 05N to 15N between 86W and 92W. The
1800 UTC NHC Tropical Weather Outlook predicts that a low
pressure will from in association with this wave by mid-week
several hundred miles south of the southern coast of Mexico, and
there is a chance this system could develop into a tropical
cyclone late this week as it moves westward to west-

A tropical wave with axis along 99W from 02N to 17N appears to be
weakening as it moves west at 10 to 15 kt. There remains some
scattered convection within about 150 nm W of the wave axis from
06N to 10N. This wave is forecast to dissipate by mid-week.

A tropical wave with axis along 108W from 02N to 17N is moving
westward at 15 kt. Significant moisture and instability in the
vicinity of this wave is leading to a broad area of numerous
showers and thunderstorms with scattered strong convection from
06N to 15N between 103W and 112W. Gusty winds are likely
occurringwith the stronger thunderstorms.

A tropical wave with axis along 129W from 02N to 15N is producing
scattered showers and thunderstorms with isolated strong
convection within about 180 nm E of the axis from 06N to 11N.
This wave is expected to continue moving west at 10 to 15 kt and
enter the Central Pacific by late week.


The monsoon trough axis extends from a 1010 mb low along the
northern coast of Colombia across Panama and southern Costa Rica
to near 09N89W to 08N100W to 13N115W to 12N122W, where trade
winds suggest it transitions to the ITCZ. The ITCZ then continues
to 11N127W, where it is interrupted by the tropical wave with the
axis near 129W. The ITCZ then re-forms at 08N131W and continues
beyond 09N140W. In addition to areas of convection described
above in the Tropical Waves section, scattered showers and
thunderstorms are located within 120 nm of the monsoon trough
between 80W and 82W and between 112W to 122W. Scattered moderate
showers and thunderstorms are also occurring within 120 nm of the
ITCZ between 122W and 127W.


Several afternoon scatterometer passes showed light to gentle
winds over most of the waters, due to a quite weak pressure
pattern. Earlier altimeter imagery recorded waves heights for
most areas of 5 to 7 ft from long-period southwest swell. This
swell should gradually subside through the week. A trough over
the Gulf of California will strengthen over the next few days as
low pressure deepens over the southwestern United States. The
result will be fresh to possibly strong southerly winds in the
central and northern Gulf of California Tuesday into Wednesday.

North and northwest swell being generated by gales off the west
coast of the United States will propagate into waters west of
Baja California Norte Tuesday into Wednesday, mixing with
southwest swell and building wave heights to 8 to 9 ft. This
swell should decay Thursday and Friday.


Gentle to moderate east to northeast winds are indicated by
afternoon scatterometer data off Central America, north of the
monsoon trough. Moderate to fresh south to southwest winds are
occurring south of the trough, off Colombia and Ecuador. For
waters near the Gulf of Papagayo, fresh to possibly strong
easterly winds will pulse during the evenings through mid-week,
leading to seas of around 8 ft.

Long-period cross-equatorial southwest swell will continue to
lead to seas of 5 to 7 feet across the waters, with wave heights
south of the equator reaching 8 to 9 feet at times through the


What was the remnant low of former Tropical Depression Four-E
has now opened into a trough, with the axis stretching from
21N118W to 14N123W. ASCAT data from around 1800 UTC depicts
moderate northwest winds to the northwest of this trough with
seas of 4 to 6 feet according to an afternoon altimeter pass.
Little convection is occurring with the trough, which is
expected to weaken further as it drifts westward Tuesday, then
dissipate Tuesday night.

A nearly stationary high pressure is centered north of the
forecast area at 33N140W, with a pressure of 1025 mb. A ridge
axis extends southeastward to 30N135W just southwest of the
southern tip of Baja California Sur. Moderate to fresh
northeasterly trades are occurring southwest of the axis and
north of the monsoon trough and ITCZ.

Long-period southwest swell continues across much of the waters
south of 20N. Altimeter passes this afternoon continue to show
wave heights of 8 to 9 ft to the south of 18N and west of 110W.
The swell will gradually decay through mid-week, allowing seas to
gradually subside.

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