Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Tropical Storm Aletta Forms West of Mexico

Tropical Storm Aletta formed over the Eastern North Pacific Ocean west of Mexico on Thursday afternoon.  This is the latest date for the formation of the first tropical storm over the Eastern North Pacific basin during the satellite era.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Aletta was located at latitude 17.9°N and longitude 107.0°W which put the center about 190 miles (310 km) west-southwest of Manzanillo, Mexico.  Aletta was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1005 mb.

A low pressure system over the Eastern North Pacific Ocean west of Mexico strengthened on Thursday afternoon and the U.S. National Hurricane Center designated the system as Tropical Storm Aletta.  More thunderstorms formed near the center of Aletta’s circulation.  Thunderstorms were also occurring in a band in the western part of Tropical Storm Aletta.  Bands in the other parts of Aletta’s circulation consisted primarily of showers and lower clouds.  Storm near the center of Aletta began to generate upper level divergence that pumped mass away from the tropical storm.

The circulation around Tropical Storm Aletta was very small.  Winds to tropical storm force extended out 45 miles (75 km) in the northern half of Aletta’s circulation.  The winds in the souther half of Tropical Storm Aletta were blowing at less than tropical storm force.

Tropical Storm Aletta will move into an environment that will become unfavorable for intensification during the next 24 hours.  Aletta will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the southern part of an upper level ridge over the Southwest U.S.  The upper level ridge will produce easterly wind that will blow toward the top of Aletta’s circulation.  Those winds will cause moderate vertical wind shear.  Tropical Storm Aletta could intensify a little during Thursday night, but cooler water and moderate wind shear are likely to end the intensification by Friday morning.  Aletta is likely to weaken to a tropical depression on Friday.

Tropical Storm Aletta will move around the southern side of a high pressure system over the Eastern North Pacific Ocean.  The high pressure system will steer Aletta toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Aletta will move farther away from the coast of Mexico.

Former Tropical Storm Ramon Weakens

Former Tropical Storm Ramon weakened over the Eastern North Pacific Ocean southwest of Baja California on Sunday. At 10:00 a.m. EST on Sunday the center of former Tropical Storm Ramon was located at latitude 14.4°N and longitude 123.9°W which put it about 1085 miles (1750 km) west-southwest of the southern tip of Baja California. Ramon was moving toward the west at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1006 mb.

A large upper level trough over the Eastern North Pacific Ocean produced strong southwesterly winds that blew the top off of former Tropical Storm Ramon. The remaining circulation of former Tropical Storm Ramon in the lower levels consisted primarily of bands of showers and lower clouds. Strong upper level winds blew the tops off of any clouds that rose higher in the atmosphere.

Former Tropical Storm Ramon will move through an environment that will be unfavorable for intensification during the next 36 hours. Ramon will move over water where the Sea Surface Temperatures are near 27°C. However, the large upper level trough over the Eastern North Pacific will continue to produce strong southwesterly winds. Those winds will cause strong vertical wind shear. The strong wind shear will cause formed Tropical Storm Ramon to weaken during the next 36 hours.

Since the circulation of former Tropical Storm Ramon only exists in the lower levels of the atmosphere, it will be steered by the winds near the surface of the Earth. Former Tropical Storm Ramon will move south of a surface high pressure system over the Eastern North Pacific. The high pressure system will steer former Tropical Storm Ramon toward the west during the next 36 hours.

TD 20E Strengthens to Tropical Storm Ramon

Former Tropical Depression Twenty-E strengthened to Tropical Storm Ramon over the Eastern North Pacific Ocean southwest of Baja California on Friday evening. At 10:00 p.m. EST on Friday the center of Tropical Storm Ramon was located at latitude 13.8°N and longitude 122.6°W which put it about 1040 miles (1675 km) southwest of the southern tip of Baja California. Ramon was moving toward the north at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1005 mb.

Former Tropical Depression Twenty-E exhibited more organization on Friday evening and the U.S. National Hurricane Center upgraded it to Tropical Storm Ramon. The distribution of thunderstorms around Tropical Storm Ramon was still asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Ramon’s circulation. Bands in the western side of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical, Winds to tropical storm force extended out 35 miles (55 km) in the eastern side of Ramon’s circulation. The winds in the western side of Tropical Storm Ramon were blowing at less than tropical storm force.

Tropical Storm Ramon will move through an environment somewhat favorable for intensification during the next 12 hours. Ramon will move over water where the Sea Surface Temperatures are near 27°C. It will move under the eastern part of an upper level trough over the Eastern North Pacific. The upper level trough will produce southwesterly winds that will blow toward the top of Ramon’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but it may not be strong enough to prevent some further intensification during the next 12 hours. Tropical Storm Ramon could intensify a little during the first half of Saturday. The upper level winds are forecast to get stronger later on Saturday. Stronger upper level winds would cause the vertical wind shear to increase. More wind shear would cause Tropical Storm Ramon to start to weaken.

Tropical Storm Ramon will move around the western part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Ramon slowly toward the north during the next 24 hours. On its anticipated track, Tropical Storm Ramon will remain far to the southwest of Baja California.

Tropical Depression 20E Forms Southwest of Baja California

Tropical Depression Twenty-E (20E) formed over the Eastern North Pacific Ocean southwest of Baja California on Thursday. At 4:00 p.m. EST on Thursday the center of Tropical Depression Twenty-E was located at latitude 12.0°N and longitude 121.9°W which put it about 1090 miles (1755 km) southwest of the southern tip of Baja California. The tropical depression was moving toward the west-northwest at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1005 mb.

A low pressure system over the Eastern North Pacific Ocean strengthened on Thursday and the U.S. National Hurricane Center designated the system as Tropical Depression Twenty-E. Tropical Depression 20E had a well defined low level circulation, but it was in an environment of strong vertical wind shear. The tropical depression was under the eastern part of an upper level ridge over the Eastern North Pacific Ocean. The ridge was producing northwesterly winds that were blowing toward the top of the tropical depression. Those winds were causing strong vertical wind shear. The wind shear was causing the distribution of thunderstorms to be asymmetrical. Bands near the center of Tropical Depression 20E and in the northwestern part of the circulation consisted primarily of showers and lower clouds. Some thunderstorms were occurring in bands in the southeastern part of the tropical depression.

Tropical Depression Twenty-E will move through an environment somewhat favorable for intensification during the next 24 hours. The tropical depression will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level ridge over the Eastern North Pacific Ocean will continue to cause vertical wind shear. The wind shear will inhibit intensification. The northwesterly winds in the upper levels could weaken a little on Friday. Tropical Depression Twenty-E could intensify a little during the next 24 hours, if the wind shear decreases.

Tropical Depression Twenty-E will move around the southwestern part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer the tropical depression slowly toward the northwest during the next 24 hours. On its anticipated track, Tropical Depression Twenty-E will remain far to the southwest of Baja California.

Former Tropical Storm Pilar Weakens

Former Tropical Storm Pilar weakened on Sunday. At 10:00 p.m. EST on Sunday the center of former Tropical Storm Pilar was located at latitude 10.7°N and longitude 114.8°W which put it about 900 miles (1450 km) south-southwest of Baja California. Pilar was moving toward the west-northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1006 mb.

An upper level trough west of Baja California produced strong southwesterly winds that blew across the top of former Tropical Storm Pilar. Those winds caused strong vertical wind shear and they blew the upper and middle portions of Pilar’s circulation northeast of the circulation in the lower levels. Although there was still a well defined circulation in the lower levels of the atmosphere, the circulation of former Tropical Storm Pilar consisted of showers and lower clouds. The wind shear blew the tops off of any clouds that rose higher into the atmosphere.

Former Tropical Storm Pilar will move through an environment that will be unfavorable for intensification during the next several days. Pilar will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level trough west of Baja California will continue to cause strong vertical wind shear. The strong wind shear will prevent inhibit intensification. The lower level circulation of former Tropical Storm Pilar will spin down gradually during the next several days.

Former Tropical Storm Pilar will move around the southern part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Pilar toward the west-northwest during the next several days. On its anticipated track, former Tropical Storm Pilar will remain far to the southwest of Baja California.

Tropical Storm Pilar Keeps Moving West

Tropical Storm Pilar kept moving westward over the Eastern North Pacific Ocean south of Baja California on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Pilar was located at latitude 10.5°N and longitude 111.6°W which put it about 865 miles (1390 km) south of Baja California. Pilar was moving toward the west at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1000 mb.

Tropical Storm Pilar strengthened a little on Saturday as it continued to move westward south of Baja California. More thunderstorms formed in bands that were revolving around the center of Pilar’s circulation. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 70 miles (110 km) in the northern part of Tropical Storm Pilar. The winds in the southern side of Pilar’s circulation were blowing at less than tropical storm force.

Tropical Storm Pilar will move through an environment that will be somewhat favorable for intensification during the next 24 hours. Pilar will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge over the Eastern North Pacific Ocean. The upper level ridge will produce easterly winds that will blow toward the top of Pilar’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear may not be strong enough to prevent intensification. Tropical Storm Pilar could strengthen on Sunday.

Tropical Storm Pilar will move around the southern part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Pilar toward the west during the next 24 hours. On its anticipated track, Tropical Storm Pilar will remain far to the south of Baja California on Sunday.

Tropical Storm Pilar Speeds Westward

Tropical Storm Pilar sped westward over the Eastern North Pacific Ocean south of Mexico on Friday. At 5:00 p.m. EDT on Friday the center of Tropical Storm Pilar was located at latitude 10.1°N and longitude 104.0°W which put it about 560 miles (905 km) south-southwest of Zihuatanejo, Mexico. Pilar was moving toward the west at 20 m.p.h. (32 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1002 mb.

Tropical Storm Pilar weakened on Friday as it sped westward over the Eastern North Pacific Ocean. Thunderstorms were occurring in a couple of bands west and south of the center of Pilar’s circulation. Bands in the eastern and northern parts of Tropical Storm Pilar consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 80 miles (130 km) in the northern side of Pilar’s circulation. The winds in the southern half of the circulation were blowing at less than tropical storm force.

Tropical Storm Pilar will move through an environment that will be unfavorable for intensification during the next 24 hours. Pilar will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of a narrow, west to east upper level ridge over the Eastern North Pacific Ocean. The upper level ridge will produce easterly winds that will blow toward the top of Pilar’s circulation. Those winds will cause moderate vertical wind shear. The moderate vertical wind shear could cause Tropical Storm Pilar to weaken a little more on Saturday.

Tropical Storm Pilar will move around the southern part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Pilar toward the west during the next 24 hours. On its anticipated track, Tropical Storm Pilar will continue to move farther away from Mexico on Saturday.

Tropical Storm Pilar Moves South of Mexico

Tropical Storm Pilar moved south of Mexico on Thursday evening. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Pilar was located at latitude 10.7°N and longitude 99.2°W which put it about 465 miles (750 km) southwest of Salina Cruz, Mexico. Pilar was moving toward the west-southwest at 22 m.p.h. (35 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 998 mb.

There were not a lot of thunderstorms in the circulation around Tropical Storm Pilar on Thursday evening. A few thunderstorms persisted in a band on the northern side of the center of Pilar’s circulation. Bands in the other parts of Tropical Storm Pilar consisted primarily of showers and lower clouds. The circulation around Tropical Storm Pilar was small. Winds to tropical storm force extended out 80 miles (130 km) from the center of Pilar.

Tropical Storm Pilar will move through an environment that will be unfavorable for intensification during the next 24 hours. Pilar will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge over the Gulf of Mexico. The upper level ridge will produce northeasterly winds that will blow toward the top of Pilar’s circulation. A surface high pressure system that extends from the eastern U.S. across the Gulf of Mexico will produce strong northeasterly winds in the lower levels. The winds in the lower levels of the atmosphere will be stronger than the winds in the upper levels. The difference in wind speed will cause moderate vertical wind shear. The wind shear will inhibit intensification. In addition, the high pressure system will continue to pump cool dry air over the Gulf of Tehuantepec. The effects of the cool dry air and the moderate vertical wind shear will cause Tropical Storm Pilar to weaken on Friday.

Tropical Storm Pilar will move around the southern part of the surface high pressure system. The high pressure system will steer Pilar toward the west-southwest during the next 24 hours. On its anticipated track, Tropical Storm Pilar will move farther away from Mexico on Friday.

Tropical Storm Pilar Moves West and Weakens

Tropical Storm Pilar moved toward the west and weakened on Wednesday. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Pilar was located at latitude 12.4°N and longitude 92.6°W which put it about 315 miles (505 km) southeast of Salina Cruz, Mexico. Pilar was moving toward the west at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1002 mb.

Tropical Storm Pilar weakened on Wednesday. Many of the thunderstorms in Pilar’s circulation dissipated during the day. There were still a few thunderstorms in a band just west of the center of Tropical Storm Pilar. Bands in the other parts of Pilar’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 80 miles (130 km) from the center of Tropical Storm Pilar.

A large surface high pressure system over the eastern U.S. extended across the Gulf of Mexico to eastern Mexico. The high pressure system produced brisk northeasterly winds that transported cool dry air over the Gulf of Tehuantepec. The circulation around the western side of Tropical Storm Pilar appeared to pull some of the cool dry air into the tropical storm. The drier air reduced the relative humidity which caused the thunderstorms in Pilar to dissipate.

Tropical Storm Pilar will move through an environment that will be unfavorable for intensification during the next 24 hours. Pilar will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge over the Northwestern Caribbean Sea. The upper level ridge will produce easterly winds that will blow toward the top of Pilar’s circulation. The surface high pressure system will continue to produce northeasterly winds in the lower levels. Easterly winds in the upper levels and northeasterly winds in the lower levels will cause moderate vertical wind shear. The wind shear will inhibit intensification. In addition, the high pressure system will continue to pump cool dry air over the Gulf of Tehuantepec. The effects of the cool dry air and the moderate vertical wind shear will cause Tropical Storm Pilar to continue to weaken on Thursday.

Tropical Storm Pilar will move around the southern part of the surface high pressure system. The high pressure system will steer Pilar toward the west-southwest during the next 24 hours. On its anticipated track, Tropical Storm Pilar will remain south of Mexico on Thursday.

Tropical Storm Pilar Stalls Southwest of El Salvador

Tropical Storm Pilar stalled southwest of El Salvador on Tuesday evening. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Pilar was located at latitude 11.9°N and longitude 89.4°W which put it about 125 miles (200 km) south of San Salvador, El Salvador. Pilar was moving toward the north at 2 m.p.h. (3 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 994 mb.

A Tropical Storm Watch was in effect for the entire coast of El Salvador. A Tropical Storm Watch was in effect for the Pacific coast of Honduras including the Gulf of Fonseca. A Tropical Storm Watch was in effect for the portion of the coast from Puerto Sandino, Nicaragua to the border with Honduras.

Tropical Storm Pilar intensified a little more on Tuesday. Even though the wind speed increased, the distribution of thunderstorms in Pilar remained asymmetrical. The strongest thunderstorms were occurring in bands in the northwestern part of Pilar’s circulation. There were also thunderstorms in the northeastern part of Tropical Storm Pilar. Bands in the southern half of Pilar’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 90 miles (145 km) from the center of Tropical Storm Pilar.

Tropical Storm Pilar will move through an environment that will be marginally favorable for intensification during the next 24 hours. Pilar will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge over the Northwestern Caribbean Sea. The upper level ridge will produce easterly winds that will blow toward the top of Pilar’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification. If the wind shear increases, it could cause Tropical Storm Pilar to weaken a little on Wednesday. Otherwise, Pilar could maintain its intensity during the next 24 hours.

A large high pressure system over the eastern U.S. extends across the Gulf of Mexico to eastern Mexico. The high pressure system will start to steer Tropical Storm Pilar back toward the west during the next 24 hours. On its anticipated track, Pilar will start to move farther away from El Salvador on Wednesday. Bands in the eastern part of Tropical Storm Pilar could bring gusty winds and locally heavy rain to the coast of El Salvador, southwestern Honduras and northwestern Nicaragua. Prolonged, heavy rain could cause flash floods in some locations.