000 AXPZ20 KNHC 280942 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Jul 28 2021 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 0930 UTC. ...TROPICAL WAVES... A tropical wave with its axis along 89W extends from the Gulf of Honduras to western Honduras and to near 05N. It is moving westward at 5-10 kt. Scattered moderate to isolated strong convection is noted within 120 nm west and 60 nm east of the wave from 11N to 14N. Small isolated showers and thunderstorms are within 120 nm either side of the wave axis from 05N to 11N. A tropical wave has its axis along 105W from 03N to 15N, moving westward near 15 kt. Scattered moderate to isolated strong convection is within 240 nm east of the wave axis from 09N to 13N. Scattered moderate convection is within 150 nm west of the wave axis. A tropical wave has its axis near 120W from 03N to 18N. Scattered moderate convection lags the wave east to 115W and from 15N to 18N. A tropical wave has axis along 135W from 03N to 15N. It is moving westward at 10-15 kt. Isolated showers and thunderstorms are within 60 nm of the wave axis from 10N to 14N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the far southwestern Caribbean Sea to 09N84W to 10N94W to low pressure near 10N104W 1009 mb to low pressure near 13N118W 1008 mb and to 10N124W. The ITCZ extends from 10N145W to 10N133W, where it briefly pauses to the east of the tropical wave along 135W. It resumes at 10N136W to 09N140W. Numerous moderate convection is within 90 nm SE and 120 nm SW quadrants of the low pressure near 13N118W. Scattered moderate to isolated strong convection is within 120 nm north of the ITCZ west of 136W, and within 30 nm of the ITCZ between 130W- 132W. Scattered moderate convection is within 120 nm south of the trough between 90W-94W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A relatively weak pressure gradient supports gentle to locally moderate northwest winds over the Baja California offshore waters with seas in the 3 to 4 ft range in SW swell. The earlier fresh northeast winds gap winds in the Gulf of Tehuantepec have ended for the time being, with winds there presently being of light to gentle speeds and east to southeast in direction along with seas of 4-6 ft due to a south to southwest swell. Fresh north gap winds are expected to begin to pulse again in the Gulf of Tehuantepec beginning this morning. After tonight these winds will pulse at fresh to strong speeds through the upcoming weekend and into early next week. Light to gentle variable winds are elsewhere with seas mainly to 3 ft. Otherwise, scattered showers and thunderstorms are noted within 90 nm offshore of the coast of the Jalisco area. For the forecast, a tighter pressure gradient will develop along the Gulf of California beginning late this afternoon or evening allowing for moderate to locally fresh northwest winds to develop over the Baja California offshore waters through Sat. Moderate southeast winds will also develop along the Gulf of California Thu night through Fri night. Low pressure is forecast to develop several hundred miles offshore of the southwestern coast of Mexico later this week, with the potential for it to develop into a tropical cyclone over the weekend while moving in a westward or west-northwestward direction. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate south to southwest winds will remain south of the monsoon trough through the forecast period along with a southwest swell that will build seas to 5-7 ft. Moderate to locally fresh northeast to east winds will continue over the Papagayo region and waters downstream from there through Sun, then diminish slightly Sun night. Seas of 3-6 ft due to a southwest swell will change little over Gulf of Papagayo region during the next few days. The weather over the offshore waters of Costa Rica and Colombia will be unsettled over the next few days due to instability associated with passing tropical waves. REMAINDER OF THE AREA... Several tropical waves are across the region enhancing convection along and near the monsoon trough and ITCZ area. Aside from the convection, these waves are supporting moderate to locally fresh northeast to east winds from 10N to near 20N and west of about 113W, with seas in the 5-7 ft range. Weak high pressure present north of 20N and to the west of 128W supports gentle to moderate north to northeast winds along with seas to 5 ft due to a south swell. Weak low pressure of 1015 mb is centered near 28N126W, with a trough to 30N124W. No convection is observed with the low as it is located within a stable and dry surrounding atmospheric environment. For further information about the waves, see section above. Otherwise, an area of low pressure is expected to develop later this week several hundred miles offshore of the southwestern coast of Mexico. Environmental conditions are forecast to be favorable for some gradual development thereafter, and a tropical cyclone could form this weekend while the system moves westward or west-northwestward. This system has a medium chance of development within the next 5 days. $$ Aguirre