812 AXPZ20 KNHC 160900 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Jul 16 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURE... A broad area of low pressure is analyzed as a 1008 mb surface low at 13N138W. Strong to near gale force easterly trades are observed within about 600 nm over the NW semicircle of the low center. Scattered moderate and isolated strong convection is currently observed within 150 nm either side of a line from 09N135W to 14N140W with banding now becoming more organized and persistent. Associated conditions should be W of 140W early Tue. This system has a high potential to become a tropical cyclone during the next 5 days with gale conditions forecast within 24 hours. Refer to the EPAC Tropical Weather Outlook under AWIPS/WMO headers MIATWOEP/ABPZ20 KNHC, and Central Pacific High Seas Forecast under AWIPS/WMO headers HFOHSFNP/FZPN40 PHFO for additional information. ...TROPICAL WAVES... A tropical wave is analyzed N of 03N along 81W and is estimated to be progressing W at 12 kt. Scattered moderate and isolated strong convection is flaring intermittently across the Pacific within 180 nm of the wave axis. A tropical wave is analyzed from 04N89W to 15N90W, and is estimated to be progressing W at 15 kt. Isolated moderate and strong convection is noted within 210 nm of the wave axis. A tropical wave is analyzed from 05N101W to 15N101W and is estimated to be progressing W at 15 kt. Scattered moderate and isolated strong convection is observed within 180 nm either side of the wave axis. A tropical wave is analyzed from 06N113W through a 1009 mb surface low embedded along the wave at 10N113W to 18N113W. This system is moving W at 18 kt. Scattered moderate and isolated strong convection is observed within 270 nm either side of the wave axis. Recent scatterometer winds detected a large area of near gale force winds and minimal gale force winds in convection within 180 nm over the NE semicircle of the surface low. The surface low is forecast to lose identity by early Tue. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W off the Pacific coast of Colombia at 08N78W and continues w through tropical waves at 08N81W, 08N88.5W and 07N101W. Scatterometer winds indicate an ITCZ develops at 08N103W and extends NW to the surface low at 10N113W, then turns SW to 08N126W, then NW to the surface low at 13N138W. Except as mentioned near the tropical waves and tropical lows, isolated moderate to strong convection is observed N of 05N E of 104W. Scattered moderate isolated strong convection is noted elsewhere within 150 nm either side of a line from 14N109W to 08N121W to 10N135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Pulses of strong to near gale force northerly drainage flow, accompanied by 6 to 9 ft seas, will continue through the middle of this morning, followed by strong northerly nocturnal pulses through Wed night. A surface ridge will meander across the area from near 23N116W to near 14N97W this week. A moderate NW breeze will develop within 90 nm of the Baja Peninsula during the evenings, otherwise gentle anticyclonic northerly winds are expected around the ridge axis accompanied by 3 to 5 ft seas. Gulf of California: Moderate southerly flow will continue between 30N and 31N through sunrise this morning with these conditions developing again on Tue night and continuing through Wed morning. Elsewhere, light to gentle southerly flow expected for the next few days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong NE-E winds will continue across, and within 180 nm downstream, of the gulf waters through this afternoon, followed by strong nocturnal pulses through the upcoming weekend. 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. Extended model guidance is suggesting that long period southerly swell, in the form of 7 to 8 ft seas, will arrive along 03.4S to the E of 93W late Wed night, and propagate N reaching the far offshore waters between 10N and 13N W of 93W during next weekend. REMAINDER OF THE AREA... Refer to Special Features section above for information on a surface low near 13N138W that has high potential to become a tropical cyclone. A surface ridge will meander across the discussion area from 32N140W to 23N116W this week, with moderate to locally fresh anticylonic flow forecast elsewhere around the ridge accompanied by 4 to 7 ft seas. Long period cross-equatorial swell, in the form of 7-9 ft seas, will move across the equator between 90W and 125W late Wed, and continue to propagate N across the discussion area S of 10N between 92W and 135W during the upcoming weekend. Long period northerly swell, in the form of 7-9 ft seas, will arrive along 32N between 125W and 132W on Thu night, and cover the waters from 30N to 32N between 130W and 140W during the upcoming weekend. $$ Nelson