000 AXPZ20 KNHC 270959 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Jul 27 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 0945 UTC. ...TROPICAL WAVES... The southern part of a Caribbean Sea tropical wave extends along 78W to across Panama and to near 05N. It is moving westward at about 10 kt. Scattered moderate convection is east of the wave to inland northwest Colombia. A tropical wave has its axis extending from the Gulf of Honduras along 87W south to near 04N. It is moving westward at 10-15 kt. Only isolated showers and thunderstorms are noted within 120 nm either side of the wave from 04N to 10N. A more pronounced tropical wave has its axis extending from 18N1145 to low pressure near 13N116W 1010 mb to 10N116W and to 04N116W. An increasing area of scattered moderate to isolated strong convection is noted east of the wave from 09N to 12N between 110W-116W. Scattered moderate convection is within 30 nm of the low. An overnight ASCAT pass showed gentle northeast to east northeast of the low to 112W, and gentle to moderate east- southeast of the low to near 110W. This system has a low chance of tropical cyclone formation through the next 5 days. A tropical wave has its axis along 129W from 04N to 17N. It is moving westward at 10-15 kt. An increasing area of scattered moderate to isolated strong convection is east of this wave from 09N to 11N between 122W-129W. Scattered moderate convection is within 30 nm of the wave from 08N to 10N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from northwestern Colombia to across northern Coast Rica, then to 10N85W to 09N100W to low pressure near 13N116W 1010 mb and to 11N122W. The ITCZ extends from 10N132W to 14N140W. Scattered moderate to isolated strong convection is 30 nm of the trough between 1119W-122W. Scattered moderate convection is within 30 nm south of the trough between 80W-83W and between 88W-91W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A relatively weak pressure gradient supports light to gentle northwest winds over the Baja California, Colima and Guerrero offshore waters with seas in the 3 to 5 ft range in SW swell. Gentle light and variable winds are over the Gulf of California, with seas to 3 ft. Winds over the Gulf of Tehuantepec are east to southeast at gentle to moderate speeds, except north of 15N between 95W-96W where mainly moderate northeast to east flow is present. Seas in the Gulf of Tehuantepec region are 5-7 ft due to a southwest swell. Deep atmospheric moisture in the wake of a recent tropical wave passing across the offshore waters of southeastern Mexico is resulting in scattered showers and isolated thunderstorms over the Oaxaca and Chiapas offshore waters. Weakening scattered showers and thunderstorms are seen within about 90 nm offshore the coast of Michoacan. Scattered showers and thunderstorms are within 60 nm offshore the coast of Colima and within 30 nm or less offshore the coast of the state of Jalisco. For the forecast, a tighter pressure gradient will develop along the Gulf of California beginning Wed afternoon allowing for moderate to fresh northwest winds to develop over the Baja California offshore waters through Fri night, and for moderate to locally fresh southeast winds over the central and southern portions of the Gulf of California Thu night through Fri. Moderate to locally fresh northeast to east winds will continue to pulse throughout the week in the Gulf of Tehuantepec and will be enhanced Thu night into Fri as low pressure develops south of this region with the potential to develop into a tropical depression late this week or over the weekend while moving in a west-northwestward direction offshore the coast of southern Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate to locally fresh south to southwest winds will continue south of the monsoon trough through the forecast period along with a southwest swell that will build seas to the range of 5-7 ft. Gentle to moderate northeast to east winds will dominate the Papagayo and adjacent waters north of the monsoon trough through Fri night, with seas to 5 ft due to a southwest swell. These winds will become gentle to moderate in speeds Sat and Sat night. Scattered moderate to isolated strong convection is over and just inland the coasts of southeastern Mexico and Guatemala to near 14N92W. The weather over the offshore waters west of Costa Rica will be rather unsettled over the next few days. Low pressure is forecast to develop a few hundred miles south or southeast of the Gulf of Tehuantepec in a few days. Thereafter, environmental conditions appear conducive for some gradual development and a tropical depression could form late this week or over the weekend while the system moves in a general west-northwestward direction. REMAINDER OF THE AREA... The gradient between a weak surface ridge over the northwest part of the forecast and trough just west of area near 141W is allowing for fresh northeast to east winds to exist from 14N to 24N west of 131W, where seas are in the 6-8 ft range due to a combination of wind waves and a southeast to south swell present there. As the trough continues to pull off farther west this morning, this will allow for the gradient to relax some and thus the 6-8 ft seas will subside slightly to 5-7 ft. An area of fresh north winds is over the northern waters north of 24N and between 126W-135W. Seas there are in the 5-7 ft range. These winds are forecast to gradually shift westward through the rest of the week as weak low pressure forms near 28N125W. The low pressure will weaken to a trough late Wed night. An overnight ASCAT pass highlighted moderate to fresh southerly winds south of the trough between 105W-124W. Elsewhere, gentle to moderate northeast to east trades are expected through late week, except south of about 18N, where the low pressure that is on the tropical wave along 116W as discussed above will move westward, with some possible gradual development. Expect some increase of winds and seas over the waters south of 18N and west of 120W. It presently has a low chance of tropical cyclone formation over the next 5 days. $$ Aguirre