000 AXPZ20 KNHC 290325 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Jul 29 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 0315 UTC. ...SPECIAL FEATURES... Low pressure of 1007 mb is centered along the monsoon trough near 14N120W. Latest satellite imagery shows numerous moderate convection within 150 nm of the low in the E quadrant. Scattered moderate to isolated strong convection is 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 30 nm of a line from 17N118W to 17N120W. The low remains fairly elongated as it being impinged upon by light northwest shear aloft. The latest ASCAT pass over the low indicated fresh to strong southwest winds in the southeast quadrant and fairly light to moderate winds on its northern periphery. This low pressure has a medium chance of becoming a tropical cyclone during the next 48 hours. Even it does not expect strong winds and seas to 8 to 9 ft near this low pressure over the next few days. Please see the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... A new tropical wave has entered the far eastern part of the area with its axis along 78W north of 03N. It is moving westward at about 18 kt. An isolated thunderstorm is over southern Panama near 08N78W. Otherwise, no deep convection is noted with this wave. A tropical wave with its axis along 94W extends from the Gulf Tehuantepec region to near 04N. It is moving westward at 10 to 15 kt. Scattered moderate to strong convection is increasing within 60 nm east of the wave north of 14N to inland southeastern Mexico. Scattered moderate convection is also west of the wave north of 13N to inland Guatemala and between 92W-93W. A tropical wave has its axis near 124W from 03N to 18N, moving westward at 10-15 kt. No significant convection is evident near this tropical wave. A tropical wave has axis along 137W from 03N to 16N. It is moving westward at 10-15 kt. Scattered moderate to isolated strong convection is noted from 08N to 14N between 137W and 140W, and also east of the wave from 08N to 12N between 131W- 137W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Colombia near 09N77W to across northern Panama and central Costa Rica continuing to 10N94W to low pressure near 12N105W 1007 mb to 10N114W and northwest to 10N125W to low pressure near 14N120W and to 10N126W. The ITCZ continues from 10N125W to beyond 10N140W. In addition to the convection described in the Tropical Waves section above, scattered moderate to isolated strong convection is seen within 120 nm south of trough between 120-122W and within 60 nm south of trough between 100W-108W. Scattered moderate convection is within 120 nm south of trough between 97W-100W and within 30 nm of ITCZ between 129W-133W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh north gap winds are pulsing across the Gulf of Tehuantepec, between relatively higher pressure to the north of the region and lower pressure farther south. Light to gentle variable winds are elsewhere with seas mainly to 3 to 5 ft due to a south to southwest swell. Farther north, a relatively weak pressure gradient supports gentle to locally moderate northwest winds over the Baja California offshore waters with seas in the 3 to 5 ft range in SW swell. For the forecast, high pressure north of the area and lower pressure farther south will support pulses of gap winds across the Gulf of Tehuantepec and off western Oaxaca tonight and Thu night. Mostly moderate winds and seas will persist elsewhere. Looking ahead, seas will build off southern Mexico starting late Sat due to increased southerly swell. A broad area of low pressure has formed several hundred miles offshore the southwestern coast of Mexico. Environmental conditions are forecast to be conducive for continued gradual development, and a tropical cyclone could form this weekend or early next week while the system moves westward or west-northwestward. 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 into early next week. Seas of 3-6 ft due to a southwest swell will change little over Gulf of Papagayo region during the next few days. For the forecast, fresh to strong gap winds may pulse tonight across the Gulf of Papagayo and again Thu night into Fri. Elsewhere, gentle to moderate south to southwest winds will dominate the waters south of the monsoon trough through the forecast period along with southwest swell. 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... See the Special Features section above for details on a low pressure system that has potential for tropical cyclone formation. An upper trough is along 123W and north of 25N. This feature is weakening the subtropical ridge and creating northwest shear over the Special Features low pressure system. Over the eastern part of the area, low pressure area is centered near 12N105W with an estimated pressure of 1007 mb. Latest satellite imagery shows that this low pressure area is broad, but convection with it has increased during the past few hours. This convection consists of the scattered moderate to isolated strong type intensity within 280 nm of the low in the SE quadrant and within 180 nm of the low in the SW quadrant. Scattered moderate convection is from 08N to 10N between 108W- 110w and within 60 nm of line from 12N104W to 12N106W. Latest ASCAT data from a few hours ago revealed a few moderate to fresh northeast winds on the north side of the low, but mostly gentle to moderate winds are evident and seas are likely no more than six feet near the low. Elsewhere, relatively weak high pressure is present with the associated gradient allowing for generally moderate northeast trades to persist north of the monsoon trough and moderate south to southwest winds farther south, with 5 to 7 ft seas in mixed swell in most areas. Larger southerly swell is noted south of the equator. $$ Aguirre