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000
AXPZ20 KNHC 202215
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Wed Sep 20 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 meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through 2115 UTC.


...TROPICAL WAVES...

A tropical wave along 98W N OF 09N is moving west at 5-10 kt. Afternoon ASCAT imagery suggests a weak 1009 mb low pres center near 14.5N96W. Scattered moderate to strong convection associated with the wave is occurring from 10N to 18N between 92W and 104W. Global models suggest an elongated trough will persist offshore of the coast across this region, and that environmental conditions are favorable for low pres to become organized S of Mexico during the next few days.


..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough stretches across the entire basin from the coast of Panama near 09N74W TO 14.5N96W TO 10N122W TO beyond 13N140W. Scattered moderate to strong convection is within 180 nm either side of trough from 78W to 86W and within 150 nm S of the through between 105W and 114W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A surface ridge extends SE into the region from a 1032 mb high near 39N150W to near 27N116W. Low pressure over southern Arizona and an approaching cold front pushing southward along the coast of California will induce fresh to strong SW winds in the northern part of the Gulf of California tonight through early Fri morning, with max seas building to 5-6 ft north of 30N. The local effects will be less evident west of Baja California and south of 29N in the Gulf of California. Elsewhere, the possible development of low pressure along the coastal waters of southern Mexico Thu or Fri will increase winds and seas south of the Mexican coast between 97W and 105W.

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

A fairly active monsoon trough along the coast of Central America from Guatemala to Panama will increase convective activity in coastal waters the next few days. Expect SW winds south of the trough axis to gradually strengthen to 10-15 kt and become more westerly by Fri. Further south, gentle to moderate southerly winds are expected to persist south of 05N through the weekend. S to SW swell continues to propagate across the area with seas in the 4 to 6 foot range east of 100W.

REMAINDER OF THE AREA...

The post-tropical remnant low of Norma of 1008 mb is near 22N117W and remains a well defined swirl of low level low clouds and stratiform convection. Winds are estimated to be 20-25 kt NW of the center and seas to 8 ft. The low will move slowly W to NW and weaken through Friday.

The post-tropical remnant low of Otis of 1009 mb is near 16.5N131W and remains a swirl of multilayered clouds and stratiform convection. Fresh to strong N-NE winds and 8-9 ft seas are with 150 nm NW of the low center. The low is expected to move SW and weaken into a trough through Friday, with seas gradually diminishing to 6-7 ft.

NW swell associated with strong N-NW winds north of the area is producing combined seas of 8-9 ft north of a line from 30N119W TO 26.5N133W TO 27N140W. This area of 8-9 ft seas is expected to contract and shift slightly eastward through Thu night. Another weaker round of NW swell associated with a cold front west of California is expected to arrive Fri night. High pressure centered well N of the area and lower pressure associated with the convergence zone will maintain moderate trade winds across most of the remainder of the area through the weekend.

$$ Stripling

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