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AXPZ20 KNHC 182205
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Oct 18 2018

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.


...SPECIAL FEATURE...

An extensive area of disorganized showers and thunderstorms extends from Central America westward to the south of the coast of Mexico for about 300 nm. A broad area of low pressure is embedded within this region of disturbed weather near the Gulf of Tehuantepec. Moreover, satellite images indicate that the system has lost organization compared to the past couple of days. However, environmental conditions still appear conducive for development, and a tropical depression or tropical storm is likely to form over the weekend or early next week while the system moves generally west-northwestward near or just offshore the coast of southern Mexico. Currently, winds and seas associated with the gap wind event in Tehuantepec merged with the low pressure located near 13N95W. Fresh to strong winds are within 210 nm north semicircle of the low with seas to 10 ft. Even though that the system has slightly weakened and high pressure north of the area is forecast to decrease, there is still a window for gale-force winds to develop late Friday morning into the afternoon hours. See the East Pacific Tropical Weather Outlook under AWIPS/WMO header MIATWOEP/ABPZ20 KNHC for further details.


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

The monsoon trough extends from 13N90W to a low near 13N95W to 12N116W to 08N123W to 12N134W to 10N140W. Scattered moderate convection is from 10N to 14N between 115W and 118W, and from 07N to 15N W of 127W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

The pressure gradient between a trough along western Mexico and surface ridging west of the Revillagigedo Islands will maintain gentle to moderate NW winds W of Baja California through Tue. Seas over this region will be 4-6 ft during that period. Afterwars, seas are forecast to increase in the offshores of Baja California Sur as a low pressure/possible tropical cyclone approaches from the SE.

High pressure N of the Gulf of California is supporting fresh to strong winds N of 29N as indicated by latest scatterometer data. Seas in this area are to 5 ft. This center of high pressure is forecast to move east by Friday evening, and winds will decrease to moderate. Otherwise, gentle to moderate winds will dominate across the remainder gulf through Sun. Light to gentle winds are expected afterwards through Tue.

The gap wind event in the Gulf of Tehuantepec has merged with the area of low pressure mentioned in the Special Features section. See section above.

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

Gentle to moderate SW monsoonal flow will dominate the offshore waters through early Sun when fresh SW winds are expected to enter the offshore waters of Ecuador Colombia and Panama. Seas of 8 ft in SW swell are expected in these zones continuing through Monday.

Widespread showers and thunderstorms associated with the broad area of low pressure mentioned in the Special Features will continue to affect portions of Central America and adjacent Pacific coastal waters.

REMAINDER OF THE AREA...

A surface trough extending from 30N138W to 25N140W will dissipate tonight. Long period NW swell associated with the trough will cause seas to build to between 8 and 10 ft N of 12N W of 131W.

$$ NR

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