Eastern Pacific Tropical Weather Discussion
814 AXPZ20 KNHC 200406 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Sep 20 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 0350 UTC. ...SPECIAL FEATURES... Storm warning (EP99): Persistent but still disorganized shower and thunderstorm activity is associated with a broad area of low pressure located several hundred miles south-southwest of the southwestern coast of Mexico. Environmental conditions are conducive for development, and a tropical depression is expected to form in the next day or so as the system moves generally northward off the coast of southwestern Mexico. There is a high chance of tropical cyclone formation in the next 48 hours. Regardless of development, this system is forecast to bring gale to storm force winds and rough to very rough seas over the offshore waters from Guerrero to Jalisco tonight through Thu night. In anticipation of tropical cyclone development, a storm warning has been issued for this area. Western East Pacific (EP98): Showers and thunderstorms associated with an area of low pressure located well southwest of the Baja California Peninsula are becoming better organized. Environmental conditions are conducive for development, and a tropical depression is expected to form over the next day or so as it moves westward to west-northwestward at 10 to 15 kt across the western East Pacific. There is a high chance of tropical cyclone formation in the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook at website: www.hurricanes.gov for more details on these Invests. ...TROPICAL WAVES... A tropical wave moving across the western Caribbean Sea with axis near 83W extends southward across W Panama and its offshore waters. It is moving westward near 5-10 kt. Scattered moderate to isolated strong convection is from 01N to 10N E of 90W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N86W to 12N106W to 11N123W to 13N137W. Scattered moderate and isolated strong convection is noted N of 03N and east of 107W, and from 05N to 12N between 120W and 128W. Numerous moderate to strong convection associated with Invest EP99 extends from 07N to 17N between 100W and 108W. Numerous moderate to strong convection associated with Invest EP98 extends from 08N to 13N between 120W and 128W with scattered moderate convection elsewhere from 02N to 13N between 117W and 136W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see SPECIAL FEATURES above for more on a storm warning associated with EP99, which has a high chance for TC development in the next 48 hours. Moderate to fresh NW winds and moderate seas prevail across the Baja California offshores N of Cabo San Lazaro. Otherwise, except for the Guerrero and Michoacan outer offshores where winds and seas are starting to deteriorate due to Invest EP99, moderate or weaker winds are elsewhere along with moderate seas. Slight seas prevail along the Gulf of California. For the forecast, aside from conditions associated with Invest EP99, moderate to locally fresh NW winds will prevail across the offshore Baja California waters through early Fri morning when conditions in Baja Calaifornia Sur offshores will start to deteriorate due to the proximity of Invest EP99. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate winds are across the Gulf of Papagayo extending downstream to near 87W. Moderate or weaker winds prevail elsewhere. Moderate seas prevail over the offshore waters in long- period southwest swell. For the forecast, moderate to fresh NE to E winds will pulse in the Papagayo region through early Sun before diminishing. Gentle to moderate winds and moderate seas will prevail elsewhere. ...REMAINDER OF THE AREA... Please see SPECIAL FEATURES above for more in EP98, with a high chance for TC development in the next 48 hours. The remnant low of former Tropical Depression Fifteen-E has shifted west of the area. A second area of low pressure, EP98, is centered near 11N123W. Both of these features are embedded within the monsoon trough. The pressure gradient between these features and a 1025 mb high centered N of the area near 33N137W is supporting moderate to fresh, locally strong, winds N of the monsoon trough to near 23N and W of 120W. Moderate to rough seas cover these waters. Elsewhere, moderate winds and moderate seas are N of the monsoon trough. Fresh to strong southerly winds are feeding into EP99, where rough seas prevail. Elsewhere S of the monsoon trough, light to gentle winds, and moderate seas, prevail. For the forecast, outside of conditions with EP98 and EP99, gentle to moderate winds and moderate seas will prevail.