000 AXPZ20 KNHC 280405 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0345 UTC. ...TROPICAL WAVES... A western Caribbean Sea tropical wave has its axis along 81W and extending south to over central Panama and to near 05N. It is moving westward at 10-15 kt. Isolated showers are within 90 nm either side of the wave axis. A tropical wave with axis along 88W extends from Central America south to near 04N. It is moving westward at 10-15 kt. Scattered moderate to isolated strong convection is being enhanced by the wave over most of Honduras and El Salvador and along and just inland the coast of the northwest part of Nicaragua. Small isolated showers and thunderstorms are elsewhere within 120 nm either side of the wave axis north of 07N. A tropical wave has its axis along 104W from 03N to 16N, moving westward near 15 kt. Scattered moderate to isolated strong convection is within 180 nm east of the wave axis from 08N to 10N. Scattered moderate convection is within 180 nm west of the wave axis from 08N to 10N and within 60 nm of 11N104W. A tropical wave has its axis near 119W from 03N to 17N. This wave was recently attendant by a 1008 mb low pressure system that is presently near 13N117W. Deep convection of the scattered moderate to isolated strong type is seen within 180 nm of the low in the SE quadrant and within 150 nm of the low in the SW quadrant. Scattered moderate convection is within 60 nm east and west of the wave axis from 10N to 12N. A tropical wave has axis along 132W from 03N to 16N. It is moving westward at 10-15 kt. Isolated showers and thunderstorms are within 60 nm of the wave axis from 08N to 13N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the far southwestern Caribbean Sea to 10N104W to low pressure near 13N117W 1008 mb and to 10N125W. The ITCZ extends from 10N125W to 09N131W where it briefly pauses to the east of the tropical wave along 132W. It resumes at 09N133W to 09N140W. Aside from the convection associated with the tropical waves and the low pressure near 13N117W, scattered moderate convection is within 60 nm south of the trough between 96W-100W and also within 30 nm of the trough between 120W-122W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A relatively weak pressure gradient supports gentle to locally moderate NW 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. The gap winds are expected to begin to pulse again in the Gulf of Tehuantepec beginning Wed and continue through the upcoming weekend. Light to gentle variable winds are elsewhere with seas mainly to 3 ft. Otherwise, large clusters of scattered moderate to isolated strong type intensity convection are occurring along and inland the coasts of the Mexican states of Jalisco, Nayarit and over the southern portion of the state of Sinaloa. For the forecast, a tighter pressure gradient will develop along the Gulf of California beginning late Wed 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. Moderate to locally fresh northeast winds will pulse over the Tehuantepec region the next several nights. Low pressure is forecast to develop several hundred miles offshore of the southwestern coast of Mexico later this week, with potential for it to develop into a tropical depression 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 depression 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