--------------------------------------------------------------------------- TROPICAL WEATHER DISCUSSION (EASTERN PACIFIC AREA) MESSAGES T1T2: AX A1A2: PZ Date: 2026-08-17 --------------------------------------------------------------------------- Message File: T_AXPZ20KNHC170247_C_KWBC_20260817024813_4522426-811-TWDEP.txt ****0000007419**** AXPZ20 KNHC 170247 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Aug 17 2026 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0250 UTC. ...SPECIAL FEATURES... Heavy Rainfall in Panama and Colombia: A tropical wave, currently analyzed in the central Caribbean Sea near 75W, will cross Panama and northern Colombia through Mon, interacting with the monsoon trough and combining with enhanced divergence aloft to induce thunderstorms, particularly over the Darien region of Panama and the Choco-Colombia. Heavy rainfall from these thunderstorms may lead to flooding. ...TROPICAL WAVES... The axis of a tropical wave is along 95W from the Gulf of Tehuantepec southward to the Equator, moving quickly westward around 25 kt. An area of low pressure could form several hundred nautical miles south of the coast of southern Mexico around the middle part of the week. Nearby convection is discussed in the ITCZ/monsoon trough section below. The axis of a tropical wave is near 121W from 17N southward, moving quickly westward around 25 kt. Nearby convection is discussed in the ITCZ/monsoon trough section below. A broad area of low pressure could form well to the southeast of the Hawaiian Islands during the middle to latter part of the week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 1006 mb low pressure over northern Colombia at 11N74W to near the Gulf of Papagayo at 10N86W to 07N97W to 08N102W. The ITCZ extends from 08N102W to 08.5N121W, then resumes west of a tropical wave from 09N123W to 05N140W. Scattered to numerous moderate and isolated strong convection is noted from 02N to 14.5N between 77W and 108W, from 06N to 11N between 108W and 130W, and from 01N to 06N between 138W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Tropical Waves section above for information on a tropical wave that has a potential for tropical development offshore southern Mexico next week. Strong to near gale north gap winds are over the Gulf of Tehuantepec. Fresh northwest winds are near the Pacific coast of Baja California, locally strong near and north of Punta Eugenia. Elsewhere, winds are moderate or weaker. Seas are 6 to 8 ft over the Gulf of Tehuantepec, 5 to 7 ft over the remaining open Pacific offshore waters, and 1 to 3 ft over the Gulf of California. Scattered moderate convection is noted in the offshore waters from Guerrero southward. For the forecast, the pressure gradient between high pressure over the Gulf of America and relatively lower pressure south of Mexico will continue to induce pulses of strong north winds over the Gulf of Tehuantepec through Wed night, with moderate to fresh pulses thereafter. Winds will reach reach near gale force at times tonight, Mon night and Tue nights, while resultant rough seas are also expected. Fresh northwest winds are forecast off of the Baja California peninsula through Tue night, with winds reaching strong speeds near Punta Eugenia. Meanwhile, a surge of strong SE winds may move from near Cabo Corrientes up across the Gulf of California Mon night into early Tue, likely associated with a complex of convection. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See Special Features section above for information on heavy rainfall that may cause flooding over the next few days in portions of Colombia and Panama. Fresh to strong northeast to east gap winds are over the Gulf of Papagayo region. Seas generated from earlier slightly stronger winds have propagate well away from the source region to the south of 11N and west of 90W. Elsewhere, winds are moderate or weaker north of the monsoon trough, and moderate to fresh south of the monsoon trough. Seas are 4 to 7 ft in long- period southwest swell over the remainder of forecast waters, except to 8 ft south of the Galapagos Islands. Thunderstorms are present near the monsoon trough as described above across much of the offshore waters, with locally higher winds and seas possible near any convection. For the forecast, the pressure gradient between high pressure over the western Caribbean and relatively lower pressure over Central America will lead to fresh northeast to east gap winds over Papagayo region, locally strong to near gale-force at times with occassionally and locally rough seas as a result. Moderate to fresh winds will extend away from this area across the far offshore waters of El Salvador and Guatemala midweek. Moderate to fresh southerly winds will pulse south of the monsoon trough into Mon night. Large southerly swell will impact waters mainly from Ecuador to the Galapagos Islands through the next several days, largest expected through Wed. ...REMAINDER OF THE AREA... The low pressure associated with the remnants of Hernan is opening to a surface trough located just west of the discussion area and 140W. Some residual associated rough seas are along and just east of 140W from 16N to 22N. Another weak developing surface trough is just northeast, from near 25N132W to 20N135W. Moderate to fresh winds are found from 23N to 28N between 128W and 138W. Scattered moderate isolated strong convection is noted on satellite imagery from 17N to 30N between 125W and 133W. Some moderate to fresh winds are noted from 09N to 17N between 115W and 129W near a tropical wave described above. Moderate to fresh SE to S winds are found south of 02N and east of 126W. Winds are moderate or weaker across the remainder of the open waters. Seas are 7 to 9 ft in mixed SE and SW swell south of the Equator and west of 90W, and also elsewhere south of 03N between 110W and 130W. For the forecast, winds and seas associated with the remnants of Hernan will diminish later tonight toward 140W. Rough seas will prevail along and south of the Equator through the middle of the week. An area of low pressure could form several hundred nautical miles south of the coast of southern Mexico around the middle part of the week. Gradual development of this system is possible thereafter, and a tropical depression could develop towards the end of the week or next weekend while the system moves west- northwestward, while staying south of Mexico. In addition, a broad area of low pressure could form well to the southeast of the Hawaiian Islands during the middle to latter part of the week. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form towards the end of the week and into the weekend, while the system moves generally westward across the western portion of the east Pacific and into the central Pacific. Regardless of development, expect some increasing winds and seas with this area. $$ Lewitsky ########################### END OF MESSAGE SET ############################ --------------------------------------------------------------------------- Message File: T_AXPZ20KNHC170745_C_KWBC_20260817074616_4522426-826-TWDEP.txt ****0000007988**** AXPZ20 KNHC 170745 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Aug 17 2026 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 0720 UTC. ...SPECIAL FEATURES... Heavy Rainfall in Panama and Colombia: A tropical wave, currently analyzed near 77W, is crossing Panama will interacting with the monsoon trough and combining with enhanced divergence aloft to induce thunderstorms, particularly over the Darien region of Panama and the Choco-Colombia. Heavy rainfall from these thunderstorms may lead to flooding. ...TROPICAL WAVES... The axis of a tropical wave is along 77W from 02N near the border of Ecuador and Colombia northward to across eastern Panama near the border with Colombia, and continuing into the Caribbean Sea, moving westward around 20 kt. Refer to the Special Features section below for additional details including Heavy Rainfall. The axis of a tropical wave is along 97.5W from just offshore Oaxaca southward to the Equator, moving quickly westward around 25 kt. Nearby convection is discussed in the ITCZ/monsoon trough section below. An area of low pressure could form several hundred nautical miles south of the coast of southern Mexico around the middle part of the week. The axis of a tropical wave is near 123W from 17N southward, moving westward around 20 kt. Nearby convection is discussed in the ITCZ/monsoon trough section below. A broad area of low pressure could form well to the southeast of the Hawaiian Islands during the latter part of the week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 1007 mb low pressure near the coast of northern Colombia at 10.5N73.5W to across the border of Costa Rica and Nicaragua to the Gulf of Papagayo at 11N84.5W to 07N102W. The ITCZ extends from 07N102W to 08N122W, then resumes west of a tropical wave from 07N124W to beyond 05N140W. Scattered to numerous moderate and isolated strong convection is noted from 02N to 14N between 77W and 106W, and from 05N to 13N between 115W and 131W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Tropical Waves section above for information on a tropical wave that has a potential for tropical development offshore southern Mexico later this week. Strong to near gale north gap winds are over the Gulf of Tehuantepec as confirmed by a recent ASCAT scatterometer pass. Fresh northwest winds are near the Pacific coast of Baja California, locally strong near and north of Punta Eugenia, also confirmed by ASCAT. Elsewhere, winds are moderate or weaker. Seas are 7 to 10 ft over the Gulf of Tehuantepec, 4 to 6 ft over the remaining open Pacific offshore waters, except to 7 ft near Punta Eugenia, and 1 to 3 ft over the Gulf of California. A cluster of scattered to numerous thunderstorms is propagating from portions of NW Mexico into the southern Gulf of California bringing gusty winds and squally weather including locally higher seas. For the forecast, the pressure gradient between high pressure over the Gulf of America and relatively lower pressure south of Mexico will continue to induce pulses of strong north winds over the Gulf of Tehuantepec through Wed night, with moderate to fresh pulses thereafter. Winds will reach reach near gale force at times early this morning, tonight and Tue night, while resultant rough seas are also expected. Fresh northwest winds are forecast off of the Baja California peninsula through Tue night, with winds reaching strong speeds near Punta Eugenia through this evening. Meanwhile, a surge of strong SE winds may move from near Cabo Corrientes up across the Gulf of California tonight into early Tue, likely associated with another developing complex of convection. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See Special Features section above for information on heavy rainfall that may cause flooding over the next few days in portions of Colombia and Panama. Fresh to strong northeast to east gap winds are over the Gulf of Papagayo region, with moderate to fresh winds extending well away from the Gulf to near 09N95W where locally rough seas exist. Elsewhere, winds are moderate or weaker north of the monsoon trough, and moderate to fresh south of the monsoon trough. Seas are 4 to 7 ft in long-period southwest swell over the remainder of forecast waters, except to 8 ft southwest of the Galapagos Islands. Thunderstorms are present near the monsoon trough as described above across much of the offshore waters, with locally higher winds and seas possible near any convection. For the forecast, the pressure gradient between high pressure over the western Caribbean and relatively lower pressure over Central America will lead to fresh northeast to east gap winds over Papagayo region, locally strong to near gale-force at times with occassionally and locally rough seas as a result. Moderate to fresh winds will extend away from this area across the far offshore waters of El Salvador and Guatemala midweek. Moderate to fresh southerly winds will pulse south of the monsoon trough into tonight before weakening. Large southerly swell will impact waters mainly from Ecuador to the Galapagos Islands through the next several days, largest expected later today through Wed. ...REMAINDER OF THE AREA... The remnants of Hernan and associated winds and seas have moved completely west of 140W in the past several hours. A surface trough is over the northwest waters, analyzed from 23.5N130W to 18N140W, with moderate to fresh winds from 17N to 24N to the west of 130W and the trough as captured by very recent ASCAT scatterometer data. Associated scattered moderate isolated strong convection is found on conventional infrared satellite imagery from 23.5N to 28N between 125W and 134W. Some moderate to fresh winds are also noted from 09N to 24N between 117W and 130W near a tropical wave described above. Moderate to fresh SE to S winds are found south of the monsoon trough to the east of 126W, where seas are 7 to 9 ft in mixed SE and SW swells. Winds are moderate or weaker across the remainder of the open waters, along with seas of 4 to 7 ft. Very active convection is present along the monsoon trough and ITCZ as described above, possibly leading to locally higher winds and seas. For the forecast, an area of low pressure could form several hundred nautical miles south of the coast of southern Mexico around the middle part of the week, associated with a tropical wave currently analyzed near 77W. Gradual development of this system is possible thereafter, and a tropical depression could develop towards the end of the week or next weekend as the system moves west- northwestward while staying south of Mexico. In addition, a broad area of low pressure could form well to the southeast of the Hawaiian Islands during the latter part of the week, associated with a tropical wave currently analyzed near 124W. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form towards the end of the week and into the weekend as the system moves generally westward across the western portion of the east Pacific and into the central Pacific. Regardless of development, expect some increasing winds and seas with these areas. $$ Lewitsky ########################### END OF MESSAGE SET ############################