000 AXPZ20 KNHC 012204 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Oct 1 2016 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from 09N85W to 09N96W to 10N102W to 13N110W. It resumes at 11N122W to low pressure near 09N140W 1010 mb. Scattered moderate isolated strong convection is within 120 nm south of the axis between 125W and 131W, and also within 120 nm north of the axis west of 138W. Scattered moderate convection is within 120 nm south of the axis between 89W and 91W, and within 670 nm of the axis between 80W and 84W. Similar activity is seen north of the trough axis within 30 nm of a line from 12N96W to 12N101W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak pressure gradient remains over the forecast waters, and is supporting mainly light to gentle northwesterly winds across much of the area. Northerly winds pulsed to around 30 kt late last night into this this morning across the Gulf of Tehuantepec with seas of 8-10 ft. Since 15Z this morning, these winds have diminished to the moderate to fresh range with seas now having lowered to 8 ft based on a recent altimeter pass. Strong northerly winds are forecast to materialize again late tonight, and into early Sunday morning through the Gulf in a narrow swath as high pressure over northeast and central Mexico ridges slightly southward, and interacts with broad low pressure south of the Gulf of Tehuantepec. These winds will diminish on Sunday afternoon, then are expected to pulse back up again to strong northerly winds late Sunday night, and diminish on Monday afternoon. A surface trough extends from 21N116W to low pressure near 18N115W 1011 mb to 15N113W. An Ascat pass from this afternoon showed a weak cyclonic circulation consisting of gentle to moderate winds, about 300 nm in diameter, associated with the low. Seas are generally 5-6 ft outside the Gulf of California, and 2 ft or less across all but the southern entrance to the Gulf of California. The surface trough and low will continue to slowly move westward through Sunday, then west-southwest as a dissipating trough through Monday evening. While this takes place, the sub- tropical ridge that presently extends from northwest to southeast across the northwest and north-central waters will build east- southeast and strengthen. This will tighten the pressure gradient just north of the far northeast waters through by Monday with northwest to north strong to near gale force winds just north of 30N. Northwest to north swell originating from north of 30N will propagate as far south as 26N from between Baja California Norte and 121W by Monday with resultant seas building to 9 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable winds are expected north of the monsoon trough, while gentle to locally moderate south to southwesterly winds are expected south of the monsoon trough through Monday. Combined seas of 4 to 7 ft, primarily in long-period southwesterly swell is expected across the offshore waters into early next week. REMAINDER OF THE AREA... A large upper anticyclone dominates the area east of 135W, while broad upper troughing is over the area west of 135W. As stated above, the aforementioned sub-tropical ridge will strengthen over the northern portion through Monday. The pressure gradient between the ridge and lower pressure within the monsoon trough region will tighten.This will freshen winds north of the monsoon trough early next week, with winds increasing to moderate to fresh category from 15N to 25N west of about 120W. The long fetch of these fresh trades will help build seas to the 7-9 ft from Sunday afternoon into Monday. $$ AGUIRRE