Tag Archives: Eastern North Pacific

Stronger Tropical Storm Carlotta Nears Acapulco

A stronger Tropical Storm Carlotta moved near Acapulco, Mexico on Saturday night.  At 11:00 p.m. EDT the center of Tropical Storm Carlotta was located at latitude 16.6°N and longitude 99.9°W which put it 20 miles (35 km) south of Acapulco.  Carlotta was moving toward the northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 997 mb.  A Tropical Storm Warning was in effect for the portion of the coast from Punta Maldonado to Tecpan de Galeana.

The center of Tropical Storm Carlotta remained over water on Saturday and the circulation strengthened.  A small eye formed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Storms in the core were generating upper level divergence which pumped mass away from the tropical storm.

The future intensity of Tropical Storm Carlotta will depend on whether or not the center remains over water.  The Sea Surface Temperature of the water south of Mexico is near 30°C.  Carlotta will move through an area where the upper level winds are weak.  If the center of Carlotta remains over water, then it could intensify more on Sunday.  However, if the center moves inland, then Tropical Storm Carlotta will weaken quickly when the circulation is disrupted by the Sierra Madre del Sur mountains.

Tropical Storm Carlotta moved near the western end of a ridge over Mexico.  The ridge steered Carlotta slowly toward the northwest on Saturday and that general motion is forecast to continue on Sunday.  On its forecast track the center of Tropical Storm Carlotta will move almost parallel to the coast of Mexico west of Acapulco.  A small deviation to the left of the anticipated track will keep the center over water.  A small deviation to the right of the anticipated track will bring Tropical Storm Carlotta inland.  Carlotta will cause gusty winds near the coast.  Heavy rain will fall north of the center and over the south slopes of the Sierra Madre del Sur Mountains.  Flash floods are likely because of the slow movement of Tropical Storm Carlotta.

Hurricane Bud Weakens, Watch Issued for Baja California

Hurricane Bud weakened significantly on Tuesday, but it prompted the issuance of a Tropical Storm Watch for the southern portion of Baja California.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Bud was located at latitude 18.7°N and longitude 108.6°W which put it about 300 miles (485 km) south-southeast of Cabo San Lucas, Mexico.  Bud was moving toward the north-northwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 973 mb.  The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Santa Fe to La Paz, Mexico including Cabo San Lucas.

Hurricane Bud weakened to a Category 1 hurricane on the Saffir-Simpson Scale on Tuesday.  The center of Hurricane Bud was over water where the Sea Surface Temperature was near 27°C, but much of the northern half of the circulation was over cooler water.  The slow movement of Bud may have also allowed the winds to mix cooler water to the surface.  Thunderstorms were not as tall and the bands in the northern half of the circulation consisted primarily of showers and low clouds.  The stronger thunderstorms were occurring mainly south and east of the center of Hurricane Bud.

Hurricane Bud is forecast to spin down slowly during the next several days.  Cooler water at the surface of the ocean is not likely to supply sufficient energy to maintain the circulation.  The upper level winds are weak and there is little vertical wind shear, but the lack of shear will be less important than effects of the cooler water.  The lack of stronger thunderstorms in the northern half of the circulation will limit the downdrafts that could transport stronger winds to the surface.  Hurricane Bud could weaken to a tropical storm on Wednesday if new thunderstorms do not form in the core of the circulation.

A ridge in the middle troposphere over the southwestern U.S. almost blocked the forward motion of Hurricane Bud on Tuesday.  Bud moved slowly toward the north-northwest.  A slow motion toward the north-northwest is forecast to continue for another 24 to 36 hours.  After that time a trough over the Pacific Ocean is forecast to push the ridge eastward.  When the trough approaches, stronger southerly winds will steer Bud northward more quickly.  On its anticipated track Bud is forecast to approach the southern tip of Baja California in 36 to 48 hours.

Hurricane Bud is likely to be a tropical storm when it nears Baja California.  Bud will bring gusty winds, but the bigger risk will be locally heavy rain.  Heavy rain falling on steep terrain could cause flash floods.  Bud or its remnants could also bring rain to parts of the southwestern U.S.

Bud Rapidly Intensifies Into a Major Hurricane

Hurricane Bud rapidly intensified Monday into a major hurricane southwest of Mexico.  At 11:00 a.m. EDT on Monday the center of Hurricane Bud was located at latitude 16.7°N and longitude 106.8°W which put it about 265 miles (425 km) south-southwest of Cabo Corrientes, Mexico.  Bud was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 955 mb.  A Tropical Storm Watch remained in effect for the portion of the coast from Manzanillo to Cabo Corrientes, Mexico.

The circulation around Hurricane Bud is very well organized.  A circular eye exists at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in the ring of storms.  A number of bands of showers and thunderstorms are revolving around the core of the circulation.  The overall circulation is quite symmetrical and there are rainbands in all quadrants of Hurricane Bud.  Storms near the core are generating strong upper level divergence which is pumping mass away from the hurricane in all directions.

Hurricane Bud exhibits all of the characteristics of a well organized hurricane.  Winds to hurricane force extend out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extend out about 140 miles (225 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Bud is 22.1.  The Hurricane Size Index (HSI) is 12.4 and the Hurricane Wind Intensity Size Index (HWISI) is 34.5.

Hurricane Bud will move through an environment favorable for a major hurricane for another 12 to 24 hours.  Bud is currently over water where the Sea Surface Temperature is near 29°C, but the Sea Surface Temperature of the water ahead of the hurricane is cooler.  Hurricane Bud will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Bud could intensify during the next 12 to 24 hours, because of little shear.  However, Bud is likely to weaken after that, when it moves over cooler water.

Hurricane Bud is moving near the western end of a subtropical ridge which is steering the hurricane toward the northwest.  That general motion is expected to continue for another day or so.  Bud is forecast to turn more toward the north when it reaches the western end of the ridge.  On its anticipated track the core of Hurricane Bud is expected to remain west of the west coast of Mexico.  Bud could approach the southern part of Baja California in about four days.

Elsewhere, former Tropical Storm Aletta weakened to a tropical depression.  At 11:00 a.m. EDT on Monday the center of Tropical Depression Aletta was located at latitude 16.8°N and longitude 117.8°W which put it about 665 miles (1070 km) southwest of the southern tip of Baja California.  Aletta was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1005 mb.

Hurricane Aletta Rapidly Intensifies to Category 4

Hurricane Aletta rapidly intensified Friday morning to Category 4 on the Saffir-Simpson Scale.  At 11:00 a.m. EDT on Friday the center of Hurricane Aletta was located at latitude 15.8°N and longitude 111.2°W which put it about 505 miles (815 km) west-southwest of Manzanillo, Mexico.  Aletta was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 943 mb.

An environment with warm Sea Surface Temperatures and little vertical wind shear allowed Hurricane Aletta to intensify rapidly during Thursday night and Friday morning.  A small circular eye was evident at the center of circulation.  A tight ring of strong thunderstorms completely surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of strong storms were revolving around the eastern and northern sides of the core of Hurricane Aletta.  Storms around the core were generating very strong upper level divergence which was pumping away large quantities of mass from the hurricane.  The removal of mass allowed the pressure to decrease rapidly and a stronger pressure gradient force generated much stronger winds.

Hurricane Aletta has a relatively small circulation.  Winds to hurricane force extended out about 30 miles (50 km) from the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) from the center.  The Hurricane Intensity Index (HII) was 28.3.  The Hurricane Size Index (HSI) was 10.8 and the Hurricane Wind Intensity Size Index (HWISI) was 39.1.  Hurricane Aletta is very similar in intensity and size to Hurricane Charley in 2004 when Charley hit southwest Florida.

Hurricane Aletta will remain in a favorable environment of warm water and little vertical wind shear for another 12 to 24 hours.  So, it could strengthen more in the short term.  Aletta will start to move over cooler water during the next day or so.  There will be less energy in the upper ocean to support the intense hurricane.  In addition, a upper level trough to the northwest of Aletta will produce southwesterly winds which will blow toward the top of the circulation.  Increased vertical wind shear will speed up the rate of weakening.  Since the circulation of Hurricane Aletta is relatively small, it could weaken fairly quickly.

Hurricane Aletta is moving around the southwestern part of a ridge over Mexico.  The ridge has been steering Aletta toward the west.  A turn more toward the northwest is expected when Hurricane Aletta nears the western end of the ridge.  On its anticipated track Hurricane Aletta is forecast to move farther away from the west coast of Mexico.

Tropical Storm Aletta Forms West of Mexico

Tropical Storm Aletta formed west of Mexico on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Aletta was located at latitude 14.3°N and longitude 108.4°W which put it about 425 miles (680 km) southwest of Manzanillo, Mexico.  Aletta was moving toward the west at 7 m.p.h. (11 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 999 mb.

A distinct low level center of circulation developed within a large area of showers and thunderstorms over the eastern North Pacific Ocean west of Mexico on Wednesday and the National Hurricane Center designated the system as Tropical Storm Aletta.  The circulation of Aletta was still organizing.  Several bands of showers and thunderstorms developed east of the center of circulation.  The bands in the western half of the circulation consisted primarily of showers and low clouds.  Storms near the center of circulation were generating upper level divergence which was pumping mass away from Tropical Storm Aletta.

Tropical Storm Aletta will move through an environment favorable for intensification during the next 48 hours.  Aletta will move over water where the Sea Surface Temperature is near 29°C.  An upper level trough located northwest of Tropical Storm Aletta will produce southwesterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification.  Aletta will likely strengthen into a hurricane during the next several days.

Tropical Storm Aletta is moving south of a ridge over Mexico.  The ridge is steering Aletta toward the west.  A general motion toward the west-northwest is forecast for the next several days.  On its anticipated track Tropical Storm Aletta will move farther away from the west coast of Mexico.