882 AXPZ20 KNHC 192216 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2100 UTC Thu Jul 19 2018 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 2100 UTC. ...TROPICAL WAVES... A tropical wave is analyzed N of 07N along 98W and is estimated to be progressing W at 10 to 15 kt. This may be enhanced by an upper low northwest of the trough axis. Scattered moderate and isolated strong convection is noted from 12N to 14N between 100W and 104W. A tropical wave is analyzed from 08N110W to 15N106W and is estimated to be progressing W at 15 kt. Scattered moderate and isolated strong convection is noted from 12N to 14N between 100W and 104W. A tropical wave is analyzed from 07N129W to 15N126W and is estimated to be progressing W at 15 kt. Scattered moderate convection from 06N to 13N between 122W and 132W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends 08N78W to 12N125W. The ITCZ reaches from 12N130W to beyond 11N140W. Scattered moderate to isolated strong is noted from 07N to 10N east of 95W. Scattered moderate convection is noted from 07N to 14N between 100W and 108W, and from 06N to 13N between 122W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge will persist from the north central Pacific through the Revillagigedo Islands for the next few days, maintaining gentle to moderate breezes across the Mexican offshore waters into early next week. Southerly swell will propagate into the region by late Fri, allowing seas to build to 5 to 7 ft in open waters into early next week. In the Gulf of Tehuantepec, strong gap wind flow will return by late Sat, resulting in mixed seas south of the Gulf as wind waves from northerly gap winds encounter the longer period southerly swell. The stronger gap winds will be due to lowering pressure south of the region along with localized drainage flow. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong nocturnal easterly drainage flow, accompanied by 6 to 8 ft seas, are expected into early next week. Gentle to occasionally moderate E winds are forecast elsewhere N of the monsoon trough which is meandering between 07N and 10N. Moderate southerly winds are forecast S of the monsoon trough for the next several days accompanied by 4 to 6 ft seas. Long period southerly swell, in the form of 7 to 8 ft seas, is crossing the equator, and will continue to propagate N reaching the far offshore waters between 05N and 14N W of 86W late Sun, with this swell reaching the coast of Central America on Mon. Looking ahead, global models are showing increased southwesterly flow into the monsoon trough starting by mid week. Along with strong gap winds through the Gulf of Papagayo, this will help develop areas of low pressure along the the monsoon trough in the offshore waters west of Costa Rica and Nicaragua. Look for increase showers and thunderstorms in this area into mid week. REMAINDER OF THE AREA... A surface trough will move into the waters north of 27N between 125W and 135W Fri through Sun, weakening the subtropical ridge, and maintaining moderate to occasionally fresh trade wind flow farther south. Long period cross-equatorial southerly swell, in the form of 7-9 ft seas, is moving across the equator between 90W and 125W, and will continue to propagate N reaching across the discussion area S of 17N between 80W and 133W late Sun night. Long period northerly swell, in the form of 7-9 ft seas, will arrive along 32N between 125W and 132W late Thu night, then propagate SW across the discussion waters from 30N to 32N between 130W and 140W during the upcoming weekend, and then subside on Mon. $$ Christensen