Tropical Weather Discussion
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000
AXPZ20 KNHC 160240
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sun Jun 16 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 0000 UTC surface analysis and satellite imagery through
0230 UTC.

...TROPICAL WAVES...

A tropical wave with axis along 102W from 05N to 16N is moving
westward at about 15 kt. Earlier observed deep convection near
this wave has weakened to isolated showers and thunderstorms
from 13N to 16N between 98W and 100W. This activity may flare up
again to scattered type convective activity late tonight as
instability in the vicinity of the wave attributed to a the tail-
end of a mid to upper-level trough may provide may help in
developing the convection.

A tropical wave with axis along 120W from 04N to 15N is moving
westward at about 15-20 kt. Scattered moderate convection is
occurring within 120 nm east of the wave from 12N to 15N as the
wave moves through a moist environment found to the south of
high pressure, both at the surface as analyzed at 00Z, and aloft
as indicated by models and as noted by dry air in water vapor
imagery.

The previous tropical wave that was along 139W has recently
moved west of 140W. In its wake, satellite imagery shows
isolated showers and thunderstorms from 05N to 13N west of 134W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough axis extends from NW Colombia to across the
Gulf of Panama west-southwest to a 1010 mb low pressure near
08N85W and from there to 11N96W to 11N103W to 11N112W, where
latest scatterometer data indicated that it transitions to the
ITCZ briefly ending at 11N118W. It resumes to the west of the
tropical wave analyzed along 120W at 11N122W and continues to
08N139W. Scattered moderate to isolated strong convection is
noted within 120 nm north of the ITCZ between 122W and 124W, and
also within 60 nm south of the ITCZ between 124W and 125W.
Scattered moderate convection is within 60 nm south of the
trough between 81W and 84W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

The pressure gradient between a high pressure ridge west of Baja
California and a low pressure trough along the Baja California
peninsula is maintaining moderate northwest to north winds
across most of the adjacent offshore waters where seas remain in
the 4-5 ft range. Winds and seas off Baja California will change
little through early on Mon as the ridge remains over offshore
waters. However, winds will pulse to fresh speeds near the coast
during the evening hours through Sun night mainly in the region
between Punta Eugenia and Cabo San Lazaro. Low pressure is
expected to cover a rather expansive area over the southwestern
United States and along California by late Mon afternoon in
response to a sharpening mid/upper-level trough that will pass
over those regions. This will result in a weakening of the ridge
allowing for offshore wind speeds to briefly diminish through
middle part of the upcoming week.

Mainly moderate southeast to south winds were captured by an
Ascat pass over the southern half of the Gulf of California.
These winds will diminish slightly early on Sun. By late Sun
night, gentle to moderate southeast to south winds will be over
the entire Gulf and through Mon. These winds then become light
and variable on Tue and through Wed evening. Winds will increase
to fresh speeds over the far northern part of the Gulf Mon night
before diminishing to moderate speeds early on Tue. Long-period
southwest swell is reaching the Mexican offshore waters,
however, with most of the energy spent already, the seas will
remain in the 5-6 ft ft range through the middle of the upcoming
week.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Fresh to strong nocturnal offshore winds will continue pulsing
across the Gulf of Papagayo region through the middle part of
the upcoming week, with seas peaking around 7-8 ft downstream of
the Gulf. Otherwise, fairly tranquil conditions will persist off
Central America under a weak pressure pattern. Gentle to
moderate south to southwest flow with scattered showers and
thunderstorms will prevail south of the monsoon trough through
Sun night and early into next next week.

Long-period southwest swell propagating through the southern
waters will build the waveheights to 8 ft between Ecuador and
the Galapagos Islands through the remainder of this weekend.
Wave model guidance suggests that another set of south to
southwest swell will propagate through the southern waters west
of 85W Tue night through Thu building waveheights there to
a peak of 8 ft again before they begin to subside late on Thu.

REMAINDER OF THE AREA...

A high pressure ridge prevails across the northern waters.
Moderate to fresh northeast winds are between the ridge and the
ITCZ west of 120W. Seas in this region are generally 5-7 ft based
on the latest altimeter data. Moderate to locally fresh trades
are expected to persist mainly south of 20N through the
remainder of this weekend and into early next week as a couple
of tropical waves moves south of the ridge.

Long period southwest swell will continue to propagate through
high seas areas east of 120W through Sun night. Seas will remain
8 ft or greater south of the Equator through the middle of the
upcoming week, as a reinforcing set of southwest swell is
expected to reach the far southwestern waters by Mon night.
Expect 8-10 ft seas south of the Equator and west of 100W by Tue.
Elsewhere, northwest to north swell will impact the far northern
waters west of about 125W beginning on Mon night and continuing
through Wed night as strong high pressure builds southward to
the north of the area and while low pressure lingers offshore
California. Waveheights associated with the swell will likely
build to 8-10 ft north of 28N.

$$
Aguirre


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