150 AXPZ20 KNHC 122126 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1903 UTC Wed Sep 12 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 along 115W from 04N to 13N moving westward at around 5 to 10 kt. Scattered moderate convection is now near the northern end of the wave axis from 12N to 14N between 115W and 117W. This tropical wave is likely to become diffuse and difficult to track in the next 24-48 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure over northern Colombia near 09N75W to 08N80W to 11N90W to 12N110W, then resumes from 15N126W to 13N140W. Scattered moderate convection is from 03N to 07N between 79W and 87W, and from 07N to 10N between 90W and 100W. Scattered moderate to isolated strong convection is noted from 10N to 14N between 125W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A trough is forecast to meander between the Gulf of California and the Baja California Peninsula through at least Sat. As a result, gentle to moderate winds will prevail in the Gulf of California through the remainder of the week and into the upcoming weekend. Seas will be mainly 3 ft or less, except 3 to 5 ft near the entrance of the Gulf due to long period southerly swell. A gentle to moderate NW flow will prevail across the offshore waters W of Baja California, with seas generally in the 5 to 7 ft range. Winds will slightly increase N of Punta Eugenia Fri through Sun. Marine guidance suggests winds in the 15 to 20 kt range. Additional pulses of long period southerly swell will continue to impact the entrance of the Gulf of California, and the waters W of Baja California through the upcoming weekend. A surface trough is located nearly midway between Cabo Corrientes and Los Cabos, and extends from 24N107W to a 1010 mb low pressure situated near to 19N107W. Another trough stretches from the low center to near 13N114W. Scattered moderate and isolated strong convection is seen from 15N to 22N between 106W and 110W. This shower and thunderstorm activity is showing some signs of organization. Although upper-level winds are only marginally conducive, some development of this system is possible over the next few days while the disturbance moves slowly westward. The latest Tropical Weather Outlook gives this system a low chance of tropical cyclone development during the next 48 hours, and a medium chance through 5 days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will meander between 08N and 10N during the next several days. Winds on both sides of the trough axis will be gentle to moderate, increasing to moderate to fresh S of the axis by the end of the week into the weekend as broad low pressure along the axis deepens slightly. Additional pulses of cross-equatorial southerly swell are reaching the coasts of Mexico and Central America. Seas of 7 to 9 ft are already affecting the waters between Ecuador and the Galapagos Islands, and will build to such near the Azuero Peninsula by this evening. Seas are expected to further build to 9 or 10 ft across the offshore forecast waters of Panama and Costa Rica toward the end of the week into the upcoming weekend. REMAINDER OF THE AREA... The last forecast/advisory of tropical cyclone Paul was issued by the National Hurricane Center at 12/0900 UTC, and for the first time since 14 August, the northeast Pacific has no tropical cyclones. Paul is now a well defined swirl of mainly low clouds. The most recent scatterometer pass showed 20 to 25 kt winds on the NW side of the remnant circulation, where seas are in the 8 to 10 ft range based on altimeter data. The remnant low of Paul will move westward with the associated winds and seas gradually diminishing through 48 hours. However, marine guidance continues to show a small area of 20 to 25 kt winds, with seas of 8 to 9 ft in the NW quadrant of Paul through Fri, likely due to the pressure gradient between Paul and a ridge covering the NW forecast waters. Paul should open up into a trough by Sat. Looking ahead...An area of low pressure is expected to develop well south of the southwestern coast of Mexico by the weekend. Thereafter, environmental conditions appear conducive for some development, and a tropical depression could form while the system moves generally westward to west-northwestward south of Mexico. $$ GR