000 AXPZ20 KNHC 190945 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong northerly drainage winds will begin just before sunrise this morning, quickly increase to minimal gale force before noon, and gradually to strengthen to at least 40 kt tonight, with seas building to a max of 18 ft downstream of the gulf waters near 14N95.5W late tonight. Winds will diminish below gale force on Mon morning, and gradually diminish to 20 kt or less late Mon night. 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 near 10N104W on Tue morning. Strong N winds are expected to resume on Wed morning with gale conditions on Wed evening through Fri morning. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W across the Gulf of Panama to the Pacific coast of Panama at 09N78W to 09N105W where scatterometer winds indicate a transition to an ITCZ, which continues W-NW to beyond 12N140W. Scattered moderate isolated strong convection is noted within 150 nm either side of a line from 11.5N116W to 09N125W to 12N133W. ...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 mid morning when the pressure gradient will relax, supporting moderate NW flow this afternoon through sunrise on Mon. Light N winds winds then expected through Thu with a trough forming to SW from the central Baja Peninsula 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 early afternoon. 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. 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 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, while moderate to locally fresh southerly winds, and 4 to 7 ft seas, are forecast S of the monsoon trough this week. REMAINDER OF THE AREA... 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 currently across the waters N of 28N W of 138W, will spread E across the waters generally W of a line from 32N130W to 22N140W tonight through Tue before the pressure gradient relaxes. Associated seas are expected to build to 8 to 12 ft across the waters S of 30N, while 10 to 14 ft seas are forecast from 30N to 32N. A series of cold front will approach, but stall just W of 140W through Tue night. Model guidance is suggesting a cold front will arrive at 32N140W on Wed, and stall from 32N136W to 23N140W 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. $$ Nelson