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000
AXPZ20 KNHC 180322
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
320 UTC Sat Nov 18 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 0315 UTC.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from 09N84W to 10N92W to 09N105W where it transitions to the intertropical convergence zone, and extends through 11N125W to beyond 11N140W. Scattered moderate isolated strong convection is noted from 09N to 11N W of 137W. Scattered moderate convection is noted from 11N to 14N between 123W and 127W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

High pressure is forecast to build in from the N on Sat with current gentle to moderate northerly winds across the offshore waters W of Baja California, becoming moderate to fresh NW to N winds and building seas of 6-7 ft N of 25N Sat morning through late Sun.

Gulf of Tehuantepec: A final pulse of strong northerly drainage flow, with seas building to a max of 9 to 10 ft, are forecast late tonight into early Sat morning, diminishing afterward as the high pressure over the eastern slopes of the Sierra Madre mountains weakens. Another strong cold front will enter the Gulf of Mexico late Sat, followed by strong high pressure building into northeast and central Mexico through Sun. This will support a return of strong gap winds in the Gulf of Tehuantepec by early Sun, reaching gale force Sun afternoon through Mon morning. A gale warning is now in effect for the area in the latest High Seas forecast. NWP guidance indicates winds of 35-40 kt and building seas of 14-15 ft by Sun night.

Gulf of California: Strong high pressure building north of the area over the Great Basin will support fresh to strong NW winds across the northern Gulf of California by mid-day Sat, spreading into the central and southern portions of the gulf late Sat into Sun, before diminishing late Sun. Seas are forecast to build to 6 or 7 ft across the central gulf early on Sun.

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

Gulf of Papagayo: Moderate to locally fresh NE drainage winds are forecast during the overnight hours through the middle of next week with seas building to 5 ft downstream near 10N87W.

Light and variable winds, and 3 to 5 ft seas, are expected elsewhere to the N of 09N, while moderate to locally fresh southerly winds, and 4 to 7 ft seas, are forecast S of 09N through the middle of next week.

REMAINDER OF THE AREA...

A pair of 1017 mb surface lows are centered near 28N132W and 28N128W. The associated dissipating front enters the forecast waters near 30N128W and extends to 20N138W. Earlier ASCAT-A and ASCAT-B passes from 1800-1900 UTC today indicated NE winds of 20 to locally 25 KT N of 30N with lighter winds in the discussion area. A pair of altimeter passes showed 8 to 9 ft seas in the wake of the front. The complex lows are forecast to drift in place and weaken significantly as the front dissipates by early Sat.

Strong SE to S return flow will develop across the NW waters N of 27N W of 138W by Sat night, in advance of the next cold front forecast to approach the far NW corner of the area Sun night. The front will move slowly with the strong S to SW flow persisting over the NW waters on Mon. At that time, expect fresh to strong winds and seas of 8 to 11 ft covering roughly the waters N of 24N W of 136W.

Farther S and N of the ITCZ/Monsoon trough, expect gentle to moderate trade winds and 4 to 6 ft seas through Sat, with moderate to fresh trades and seas of 6 to 7 ft by Sat evening into Sun.

$$ Cobb

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