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000
AXPZ20 KNHC 230241
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 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 meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through 0200 UTC.


...SPECIAL FEATURES...

A broad elongated area of low pressure persists along the southwestern coast of Mexico and coastal waters, from Manzanillo to just south of the Gulf of Tehuantepec. A few weak cyclonic circulations are evident in satellite imagery within this broad area, with one near 17.5N104.5W, with an estimated pressure of 1006 mb. Scattered moderate to strong convection is occurring NW of the weak low from 16.5N TO 21.5N between 104.5W and 108.5W. To the S of this low is a large area of fresh to locally strong SW monsoon winds, roughly from 10N to 13N between 103W and 115W. Model guidance indicates that this low pressure center occurring N of the zone of strong monsoonal flow has the potential to develop into a tropical cyclone as it drifts NW. The convergent monsoon winds will continue to generate widespread active convection along and near the coast of Mexico, with heavy rains likely to persist in this area several more days.


..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough stretches across the entire basin from Panama near 08N74W TO 09N83.5W TO 14N92W TO low pres near 17.5N104.5W 1006 MB TO 12N112W TO low pres near 14N137W 1010 MB TO beyond 10N140W. Scattered moderate to strong convection is from 07N TO 14N between 87W and 125W...AND from 08N TO 13N between 128W AND 140W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A weakening cold front extends from southern Arizona SW across the northern Gulf of California and Baja California Norte then WSW to beyond 24N126W. Afternoon scatterometer data showed fresh northerly winds behind the front across the offshore waters. Expect the front to push further south and weaken through early Sat, then dissipate by Sat afternoon. High pressure will build north of 25N behind the front through Sun, with NW winds increasing slightly west of Baja California Norte. Elsewhere, the possible development of low pressure along the southern coast of Mexico will increase winds and seas between 101W and 115W the next few days.

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

An active monsoon trough meandering along the coast of Central America from Guatemala to Panama will remain the focus for active convection over the coastal waters the next few days. Expect SW winds south of the trough to gradually become 20-25 knots through Saturday. Farther south, gentle to moderate south to southwest winds will persist south of 05N through the weekend. Long period SE swell from the Southern Hemisphere will maintain seas west of Ecuador and south of 01N around 7-8 ft through Sat morning.

REMAINDER OF THE AREA...

NW swell generated by strong N to NW winds north of the area are producing combined seas to 8 ft north of 25N between 114W and 122W. This area of combined seas will slowly subside during the next 24 hours. High pressure centered well N of the area and lower pressure associated with the monsoon trough will maintain moderate to occasionally fresh trade winds west of 120W through the weekend.

$$ Stripling

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