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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 180949
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Nov 17 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 0600 UTC surface analysis and satellite imagery through 
0945 UTC.

...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: Pulses of strong northerly 
drainage flow will diminish to 20 kt or less around sunrise this 
morning, with winds becoming light and variable this afternoon. 
Strong to near gale force conditions will resume late tonight in 
the wake of a cold front in the Gulf of Mexico, and then quickly 
increase to gale force on Sun morning, and continue through 
through sunrise on Mon morning, with seas building to a max of 
16 ft downstream of the gulf waters near 14N95.5W on Sun night. 
Winds will diminish to 20 kt or less around sunrise on Tue.  

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends W off the coast of Costa Rica at  
09N84W to 10N92W, then dips SW to 09N105W where scatterometer 
winds indicate a transition to an ITCZ which continues W-NW to 
beyond 11N140W. Scattered moderate convection is noted within 60 
nm of 08N95W and within 180 nm of 10N114W. Scattered moderate 
isolated strong convection is noted within 150 nm 13N125W, and 
within 90 nm either side of a line from 08N132W to 11N140W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See Special Features paragraph for Gulf of Tehuantepec Gale 
Warning. 

A NW to SE orientated ridge just beyond 250 nm seaward will 
maintain moderate to locally fresh NW flow W of the Baja 
Peninsula through sunrise on Sun when the pressure gradient will 
relax, supporting moderate NW flow through sunrise on Mon. Light 
N winds winds then expected through sunrise on Thu.

Gulf of California: Light and variable winds at sunrise this 
morning will quickly become northerly this morning with strong N 
winds developing across the gulf waters N of 30N by early this 
afternoon. These strong NW winds will shift S across the central 
gulf waters tonight surrounded by fresh NW flow elsewhere. 
Little change then expected through Sun morning when the 
pressure gradient will relax with moderate NW flow forecast 
across the entire gulf waters by sunrise on Mon, becoming light 
northerly flow Mon night.

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 weakening over the NW waters 
and should dissipate tonight as a NE to SW aligned ridge builds 
from 32N124W to beyond 20N140W. Fresh to locally strong 
southerly flow will develop across the waters N of 26N W of 134W 
tonight, with seas building to 9 ft. Expect strong southerly 
winds N of the ridge, generally across the waters N of 23N W of 
137W on Sun through Tue, with seas building 8 to 12 ft. The 
associated cold front will arrive at 32N140W late Wed, with seas 
building 12 to 18 ft W of the front through Thu. 

Moderate to locally fresh anticyclonic flow expected across the 
tropics N of the ITCZ and W of 120W through the middle of next 
week with seas building to 8 ft.

$$
Nelson