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000
AXPZ20 KNHC 231608
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Thu Nov 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 1200 UTC surface analysis and satellite imagery through 1515 UTC.


...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: 30 to 40 kt northerly winds continue across the Gulf of Tehuantepec and downstream to near 13N96W this morning, and will gradually shrink and in areal coverage to minimal gale conditions tonight through mid morning on Fri. Winds will then diminish to 20 kt or less late Sat morning. Maximum seas of 16-17 ft near 14N95.5W area occurring this morning and will subside very slowly through tonight to around 12-13 ft. The resultant NE swell will propagate SW, mixing with long- period cross equatorial swell, with seas 8 ft or higher well downstream of the Gulf of Tehuantepec along 08N between 95W and 105W on Fri night before beginning to subside. Expect winds 20 kt or less and seas less than 8 ft only briefly on Sat afternoon. Strong N winds are forecast to resume again on Sat evening with gale conditions expected just after sunrise on Sun. Latest guidance is suggesting another 30 to 40 kt event on Sun night with the gales diminishing late Mon.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from NW Colombia near 10.5N75W across Costa Rica to near 10N87.5W to 09.5N108W. The ITCZ begins near 10N115W TO 07N137W TO BEYOND 07.5N140W. Scattered moderate isolated strong convection is seen NE of a line from 04N77W TO 09N85W to the coasts. Scattered moderate to strong convection is occurring within 150 nm N and 60 nm S of the ITCZ between 115W and 119W, and between 133.5W and 139W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See Special Features paragraph above for information on the Gulf of Tehuantepec Gale Warning.

A modest high pressure ridge centered offshore of southern California has weakened locally overnight and is yielding gentle and variable winds with seas of 2 to 4 ft across the offshore waters of Baja this morning and are expected to continue today. Seas will begin to build Fri afternoon in NW swell, and peak at 4 to 7 ft at 13 to 15 seconds across the waters W of Baja Fri night, then subsiding some on Sat into Sun. Long-period NW swell in the form of 7 to 9 ft seas will reach 30N120W on Sun night, and spread S across the waters W of Baja with 8 to 13 ft seas at 17 to 19 seconds forecast W of Baja Mon night and Tue.

Gulf of California: Moderate NW flow prevails across all but far southern portions of the Gulf this morning and will continue through tonight. The pressure gradient will then relax, with light and variable winds expected Fri through Mon. Strong to near gale force NW flow is expected to develop N of 25N on Mon night through Tue night, with seas building to 12 ft across the long fetch waters.

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

Gulf of Fonseca...Fresh NW winds forecast to begin around sunrise on Mon.

Gulf of Papagayo: Fresh to locally strong NE nocturnal drainage flow forecast to begin late this afternoon into tonight, with strong pulses through Tue. Seas of 8 ft or greater will propagate SW to neat 08N92W on Tue.

Light and variable winds, and 3 to 5 ft seas, are expected elsewhere through Sun night to the N of the monsoon trough which has been meandering between 09N and 11N. Moderate NE flow expected N of the Gulf of Papagayo early Mon. Moderate southerly winds, and 3 to 6 ft seas, are forecast S of the monsoon trough.

REMAINDER OF THE AREA...

A cold front from 30N138.5W TO 28N140W will stall today with a broad surface low developing along the front near 30N140W tonight. The low will move NE of the area on Fri night with the front then moving SE to extend from 30N138W TO 26N140W Sat morning. Scattered moderate to strong convection is observed E of the front from 15.5N TO 27.5N between 137W and 142W.

Combined seas of 8 to 15 ft at 14 to 16 seconds is currently observed across the discussion waters W of a line from 30N129W TO 21.5N140W. This long period NW swell will propagate across the waters W of a line from 32N122W to 12N137W early Fri before beginning to subside.

Another cold front will move E in to the area reaching from 32N133W to 23N140W on Sat with 9 to 12 ft seas at 12 to 17 seconds in the wake of the front.

$$ Stripling

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