AXPZ20 KNHC 191557

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Sun Nov 19 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.


Gulf of Tehuantepec Gale Warning: Strong northerly drainage winds will begin around noon, quickly increase to minimal gale force into the late afternoon, and gradually strengthen to at least 40 kt tonight. The sea heights are forecast to build to a max of 18 ft downstream of the gulf waters near 14N95.5W late tonight. Winds will diminish to less than gale force on Mon afternoon, and gradually diminish to 20 kt or less by sunrise on Tuesday. The associated NE swell will propagate SW mixing with long-period cross-equatorial swell, resulting in an area of 8 ft and greater seas of across the waters from roughly 09N to 13N between 94W and 103W on Mon night, with a small area of 8 ft seas subsiding from 09N to 11N between 102W and 104W on Tue at sunrise. Strong N winds are expected to resume on Wed at sunrise, with gale conditions from Wed at sunset until Friday at noon.


The monsoon trough passes through Panama near 08N82W, and it continues to 07N86W 08N96W. The ITCZ is along 08N125W 09N120W 10N140W. Precipitation: scattered moderate to isolated strong within 270 nm to the N of the ITCZ between 113W and 126W, and within 120 nm to the S of the ITCZ between 113W and 126W.



Please read the Special Features paragraph for information about the 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 mid morning when the pressure gradient will relax, supporting moderate NW flow this afternoon through sunrise on Mon. Light N winds winds then are expected through Thu. A trough is forecast to form from the central Baja Peninsula southward, on Thu night and Fri, accompnaied by a light W to NW wind shift. Expect seas in the 4 to 7 ft range today, with these conditions resuming again late in the week, with 3 to 5 ft seas during early and mid part of the week.

Gulf of California: Strong N winds expected to continue across the gulf waters N of 25N through the late afternoon hours. The pressure gradient will relax tonight with moderate NW flow forecast across the entire gulf waters at sunrise on Mon, then becoming light northerly flow by Mon evening. Moderate to locally fresh NW flow will resume across the entire gulf on Tue and Wed, then diminishing some on Thu.


Gulf of Papagayo: Moderate to locally fresh NE drainage winds are forecast during the overnight hours tonight and on Mon night, then light drainage flow expected during the overnight hours through Thu night, with moderate to fresh nocturnal drainage resuming on Fri night.

Light and variable winds, and 3 to 5 ft seas, are expected elsewhere to the N of the monsoon trough which has been meandering between 09N and 11N. Moderate to locally fresh southerly winds, and 4 to 7 ft seas, are forecast S of the monsoon trough this week.


A NE to SW aligned ridge will meander from 32N124W to beyond 20N140W for the next several days. Strong to occasionally near gale force southerly winds and 8 to 9 foot sea heights currently across the waters N of 28N W of 138W, will spread eastward and cover the area that is N of 25N W of 137W tonight with sea heigts to 11 feet, N of 23N W of 133W on Monday night with sea heights to 12 feet. The wind speeds will be fresh to locally strong on Tuesday night, with sea heights reaching 10 feet, N of 24N W of 131W. Cold fronts will approach in a series, but they will stall just W of 140W through Tue night. Model guidance is suggesting a cold front will arrive at 32N138W late on Wed, and weaken and stall from 32N135W to 21N140W on Thu, with seas building 12 to 15 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 subsiding to 4 to 7 ft by this evening, with little change through mid week. Long period NW swell will propagate SE into the tropics w of 130W on Thu, and continue E across the tropical waters W of 120W late in the week.

$$ mt