Monthly Archives: May 2025

Alvin Weakens to a Depression

Former Tropical Storm Alvin weakened to a tropical depression over the Eastern North Pacific Ocean south of Baja California on Saturday morning.  At 11:00 a.m. EDT on Saturday the center of Tropical Depression Alvin was located at latitude 20.7°N and longitude 109.5°W which put the center about 155 miles (250 km) south of the southern tip of Baja California.  Alvin was moving toward the north at 9 m.p.h. (15 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.

Former Tropical Storm Alvin weakened to a tropical depression over the Eastern North Pacific Ocean south of Baja California on Sunday morning.  An upper level low over Baja California caused strong southwesterly winds that blew across the top of Alvin’s circulation.  Those winds caused strong vertical wind shear.  In addition, Alvin moved over water where the Sea Surface Temperatures are near 24°C.  Strong vertical wind shear and cool Sea Surface Temperatures caused former Tropical Storm Alvin to weaken.

Most of the thunderstorms in former Tropical Storm Alvin dissipated due to the strong vertical wind shear and cooler Sea Surface Temperatures.  The circulation around Tropical Depression Alvin existed primarily in the lower levels of the atmosphere.  Bands of showers and lower clouds were revolving around the center of Alvin’s circulation.  Since there were no thunderstorms to generate upper level divergence and to pump mass away, the surface pressure was increasing gradually.

Tropical Depression Alvin will move through an environment very unfavorable for intensification during the next 24 hours.  Alvin will move over water where where the Sea Surface Temperatures are near 24°C.  The upper level low over Baja California will continue to produce southwesterly winds that will blow across the top of Alvin’s circulation.  Those winds will continue to cause strong vertical wind shear.  The combination of cool Sea Surface Temperatures and strong vertical wind shear will cause Tropical Depression Alvin to continue to weaken during the next 24 hours.

Tropical Depression Alvin will move around the western part of a high pressure system over Mexico.  The high pressure system over Mexico and the upper level low over Baja California will steer Alvin toward the north during the next 24 hours.  On its anticipated track, Tropical Depression Alvin will closer to the southern end of Baja California.

Tropical Storm Alvin Weakens South of Baja California

Tropical Storm Alvin weakened on Friday as it moved over the Eastern North Pacific Ocean south of Baja California.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Alvin was located at latitude 18.1°N and longitude 109.0°W which put the center about 335 miles (540 km) south of the southern tip of Baja California.  Alvin was moving toward the north-northwest at 10 m.p.h. (16 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 1001 mb.

An upper level low over Baja California produced southwesterly winds that blew toward the top of Tropical Storm Alvin on Friday.  Those winds caused the vertical wind shear to increase.  The increase in vertical wind shear caused Alvin to weaken.  The increase in wind shear also caused the distribution of thunderstorm around Tropical Storm Alvin to become asymmetrical.  Thunderstorms were still occurring in bands in the northern side of Alvin’s circulation.  Bands in the southern side of Tropical Storm Alvin consisted primarily of showers and lower clouds.

Even though Tropical Storm Alvin weakened on Friday,  the size of the circulation did not change much.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Alvin’s circulation.

Tropical Storm Alvin will move through an environment that will become even more unfavorable for intensification during the next 24 hours.  Alvin will move over water where where the Sea Surface Temperatures are near 25°C.  It will move under the southeastern part of the upper level low over Baja California.  The upper level low will continue to produce southwesterly winds that will blow toward the top of Alvin’s circulation.  Those winds will cause strong vertical wind shear on Saturday.  The combination of cool Sea Surface Temperatures and strong vertical wind shear will cause Tropical Storm Alvin to continue to weaken during the next 24 hours.

Tropical Storm Alvin will move around the western part of a high pressure system over Mexico. The high pressure system over Mexico and the upper level low over Baja California will steer Alvin toward the north during the next 24 hours.  On its anticipated track, Tropical Storm Alvin will closer to the southern end of Baja California.

Tropical Storm Alvin Intensifies Southwest of Mexico

Tropical Storm Alvin intensified over the Eastern North Pacific Ocean southwest of Mexico on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Alvin was located at latitude 16.0°N and longitude 107.9°W which put the center about 305 miles (495 km) west-southwest of Manzanillo, Mexico.  Alvin was moving toward the northwest at 12 m.p.h. (19 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 999 mb.

Tropical Storm Alvin intensified over the Eastern North Pacific Ocean southwest of Mexico on Thursday.  The inner end of a rainband wrapped around the western side of the center of Alvin’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Tropical Storm Alvin.  Storms near the center of Alvin generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The area of tropical storm force winds increased in size when Tropical Storm Alvin intensified on Thursday.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Alvin’s circulation.

Tropical Storm Alvin will move into an environment that will become unfavorable for intensification during the next 24 hours.  Alvin will move over water where where the Sea Surface Temperatures are near 26°C.  It will move under the southeastern part of an upper level low over Baja California.  The upper level low will produce southwesterly winds that will blow toward the top of Alvin’s circulation.  Those winds will cause the vertical wind shear to increase on Friday.  The combination of cooler Sea Surface Temperatures and more vertical wind shear will cause Tropical Storm Alvin to start to weaken during the next 24 hours.

Tropical Storm Alvin will move around the southwestern part of a high pressure system over Mexico.  The high pressure system over Mexico and the upper level low over Baja California will steer Alvin toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Alvin will move parallel to the west coast of Mexico.

Depression Strengthens to Tropical Storm Alvin

Former Tropical Depression One-E strengthened to Tropical Storm Alvin over the Eastern North Pacific Ocean south of Mexico on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Alvin was located at latitude 13.8°N and longitude 106.3°W which put the center about 345 miles (555 km) south-southwest of Manzanillo, Mexico.  Alvin 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.

Former Tropical Depression One-E strengthened on Thursday morning and the U.S. National Hurricane Center designated the system as Tropical Storm Alvin.  Numerous thunderstorms formed near the center of Alvin’s circulation.  More thunderstorms also developed in bands revolving around the center of Tropical Storm Alvin.  Storms near the center of Alvin generated more upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

Winds to tropical storm force extended out 45 miles (75 km) from the center of Tropical Storm Alvin.

Tropical Storm Alvin will move through an environment favorable for intensification during the next 24 hours.  Alvin will move over water where where the Sea Surface Temperatures are near 28°C.  It will move under the western part of an upper level ridge that is south of Mexico.  The upper level ridge will produce southerly winds that will blow toward the top of Alvin’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Storm Alvin will intensify during the next 24 hours.

Tropical Storm Alvin will move around the southwestern part of a high pressure system over Mexico.  The high pressure system will steer Alvin toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Alvin will move parallel to the west coast of Mexico.

Tropical Depression One-E Forms South of Mexico

Tropical Depression One-E formed over the Eastern North Pacific Ocean south of Mexico on Wednesday afternoon.  At 5:00 p.m. EDT on Wednesday the center of the area of Tropical Depression One-E was located at latitude 11.9°N and longitude 109.7°W which put the center about 465 miles (745 km) south of Manzanillo, Mexico.  Tropical Depression One-E was moving toward the northwest at 9 m.p.h. (15 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 low pressure system over the Eastern North Pacific Ocean south of Mexico strengthened on Wednesday and the U.S. National Hurricane Center designated the system as Tropical Depression One-E.  A distinct low level center of circulation developed in the middle of a larger low pressure system south of Mexico.  More thunderstorms formed near the center of circulation.  Bands of thunderstorms also developed.  Those bands of storms began to revolve around the center of Tropical Depression One-E.  Storms near the center of circulation started to generate upper level divergence that pumped mass away from the tropical depression.

Tropical Depression One-E will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over water where where the Sea Surface Temperatures are near 29°C. It will move under the western part of an upper level ridge that is south of Mexico.  The upper level ridge will produce southerly winds that will blow toward the top of the tropical depression.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Depression One will intensify to a tropical storm during the next 24 hours.

Tropical Depression One-E will move around the southwestern part of a high pressure system over Mexico.  The high pressure system will steer the tropical depression toward the northwest during the next 24 hours.  On its anticipated track, Tropical Depression One-E will move parallel to the west coast of Mexico.

Tropical Depression Likely to Form South of Mexico

A tropical depression is likely to form over the Eastern North Pacific Ocean south of Mexico during the next several days.  A broad area of low pressure was located south of Mexico.  At 8:00 a.m. EDT on Monday the center of the area of low pressure was near latitude 10.0°N and longitude 98.0°W which put the center about 500 miles (805 km) south of Acapulco, Mexico.  The low pressure system was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1008 mb.

A broad area of low pressure was located over the Eastern North Pacific Ocean south of Mexico.  Thunderstorms were scattered inside the broad circulation of the low pressure system.  Satellite images appeared to indicate that some of the thunderstorms were beginning to organize into bands.

The broad area of low pressure will move through an environment favorable for the formation of a tropical depression during the next 48 hours.  The area of low pressure will move over water where where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is south of Mexico.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  The broad area of low pressure is likely to develop into a tropical depression during the next 48 hours.

The broad area of low pressure will move around the southwestern part of a high pressure system over Mexico.  The high pressure system will steer the area of low pressure toward the northwest during the next 48 hours.  On its anticipated track, the area of low pressure will move parallel to the coast of Mexico.