Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Sandra Quickly Intensifies into a Major Hurricane

Hurricane Sandra intensified quickly into a major hurricane on Wednesday.  At 4:00 p.m. EST on Wednesday the center of Hurricane Sandra was located at latitude 13.0°N and longitude 109.9°W which put it about 685 miles (1100 km) south of the southern tip of Baja California.  Sandra was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) which made Sandra a Category 3 hurricane on the Saffir-Simpson Scale and qualified it as a major hurricane.  There were wind gusts to 140 m.p.h. (225 km/h) and the minimum surface pressure was 967 mb.  Sandra is the ninth major hurricane to form over the Eastern North Pacific during 2015, which is a new record for that basin.

Sandra is a small well organized hurricane.  It has a well defined eye surrounded by a ring of thunderstorms, but hurricane force winds only extend out about 25 miles (40 km) from the center.  Thunderstorms in the core of Sandra are producing upper level divergence which is pumping out mass and allowing the surface pressure to decrease.  Sandra is an environment that favors further intensification.  It is over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is not much vertical wind shear.  Sandra could become a Category 4 hurricane on Thursday.

Hurricane Sandra is moving around the western end of a subtropical ridge to the east of it.  Sandra turned toward the northwest on Wednesday and it will gradually start moving more toward the north on Thursday.  A large deepening upper level trough off the west coast of North American will create southwesterly winds that will start to steer Sandra toward the northeast on Friday.  On its anticipated track Hurricane Sandra will approach the southern tip of Baja California on Friday night.

TD 22E Intensifies to Tropical Storm Sandra

A core circulation organized quickly on Tuesday inside Tropical Depression 22E and it intensified into Tropical Storm Sandra.  At 4:00 p.m. EST on Tuesday the center of Tropical Storm Sandra was located at latitude 11.9°N and longitude 107.2°W which put it about 780 miles south-southeast of the southern tip of Baja California.  Sandra was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 997 mb.

Eastern upper level winds which were blowing over the top of Tropical Depression 22E diminished on Tuesday and the depression intensified into Tropical Storm Sandra.  A primary rainband wrapped around the center of circulation  and an inner core developed near the interior end of the band.  As the band wrapped around the center of circulation a ring of thunderstorms began to take on the structure of an eyewall.  Those thunderstorms also started to generate some upper level divergence.  The circulation of Sandra is still organizing and other spiral bands are starting to form.

Tropical Storm Sandra is in an environment that is favorable for intensification.  It is over water where the Sea Surface Temperature is near 30°C.  Although there is still some vertical wind shear, it is much less than it was on Monday.  A combination of very warm water and little vertical wind shear could allow Sandra to intensify very quickly.  It is likely to become a hurricane with 12 to 18 hours and it could become a major hurricane within 24 to 36 hours.  In a couple of days Sandra will start to encounter strong upper level winds from the southwest.  The increased vertical wind shear at that time will cause it to weaken.

Tropical Storm Sandra is starting to move around the western end of a subtropical ridge that has been steering toward the north.  Sandra should gradually turn toward the north during the next 24 hours.  It is likely to move mainly toward the north until Thursday when southwesterly winds will turn it toward the northeast.  Sandra could be approaching the southern tip of Baja California by Friday night.

Tropical Depression 22E Forms Southwest of Mexico

A small center of circulation formed within a larger area of thunderstorms southwest of Mexico on Monday and the National Hurricane Center designated the system as Tropical Depression 22E.  At 4:00 p.m. EST on Monday the center of Tropical Depression 22E (TD22E) was located at latitude 10.8°N and longitude 102.9°W which put it about 465 miles (750 km) south-southwest of Acapulco, Mexico.  TD22E was moving toward the west at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1005 mb.

TD22E is still in the early stages of an organizational process.  The small center of circulation is located near the western end of a long band of thunderstorms.  There are not many thunderstorms south and west of the center and there is not much evidence of spiral bands.  A subtropical ridge northeast of TD22E is pushing the depression quickly toward the west and its rapid movement is retarding the organizational process.

TD22E is currently in an environment that is marginal for intensification.  It is over water where the Sea Surface Temperature (SST) is near 30°C, which is very favorable for intensification.  However, the ridge northeast of TD22E is causing strong easterly winds to blow over the top of the depression.  The strong vertical wind shear and the rapid motion of the depression are negative factors for intensification.

As TD22E moves farther west, the vertical wind shear is expected to decrease and the depression is expected to move more slowly.  When that happens, TD22E will be able to more efficiently use the energy it is getting from the warm water and it will intensify.  A period of rapid intensification may occur once the core of the circulation is better organized.  TD22E could become a tropical storm on Tuesday and it could become a hurricane later this week.

The subtropical ridge is steering TD22E quickly toward the west.  In another 24 to 36 hours TD22E is likely to reach the western end of the ridge.  At that time it will slow down and turn toward the north.  TD22E will encounter southwesterly winds when it moves farther north.  Those winds will push TD22E toward the northeast later this week.  On its anticipated track TD22E could be near the southern tip of Baja California by the end of the week.

TD 21E Intensifies into Tropical Storm Rick

The organization of Tropical Depression 21E improved slightly on Thursday and the National Hurricane Center upgraded it to Tropical Storm Rick.  At 10:00 p.m. EST on Thursday the center of Tropical Storm Rick was located at latitude 15.2°N and longitude 108.1°W which put it about 365 miles (585 km) southwest of Manzanillo, Mexico.  Rick was moving toward the west-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 1002 mb.

More thunderstorms formed near the center of Tropical Depression 21E for a few hours on Thursday and the improved organization prompted the National Hurricane Center to upgrade the system to Tropical Storm Rick.  The organization of Rick has diminished in recent hours. The stronger thunderstorms are located northwest of the center of circulation and there are few thunderstorms in the rest of the Rick.  An upper level ridge located east of the tropical storm is producing southerly winds over the top of Rick.  The vertical wind shear is causing the stronger thunderstorms to be northwest of the center.

Rick is over water where the Sea Surface Temperature is near 29°C.  So, there is enough energy in the ocean to support intensification.  However, the strong vertical wind shear is likely to limit intensification and it could weaken Rick if it the shear gets stronger.

The ridge east of Rick is expected to strengthen and to continue to steer the tropical storm toward the west-northwest for another day or two.  After that time Rick will reach the western end of the ridge, and the tropical storm will turn more toward the north.

Poorly Organized Tropical Depression 21E Forms West of Mexico

A low level circulation center formed in a cluster of thunderstorms west of Mexico and the National Hurricane Center decided it had enough organization to be classified as a tropical depression.  At 10:00 p.m. EDT on Wednesday the center of Tropical Depression 21E (TD21E) was located at latitude 13.2°N and longitude 106.1°W which put it about 420 miles (675 km) south-southwest of Manzanillo, Mexico.  TD21E was moving toward the north at 2 m.p.h. (3 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 1004 mb.

TD21E looked more well organized earlier today when the low level center of circulation was located within the area of thunderstorms.  The low level center is now southeast of an area of weakening thunderstorms, which is an indication that the tropical depression is poorly organized.  Most of the remaining thunderstorms are located north of the low level center.

The tropical depression is over water where the Sea Surface Temperature is near 30°C.  However, the environment is not really favorable for intensification.  An upper level ridge east of the depression is causing southerly winds over the top of TD21E.  Those winds are generating vertical wind shear over the top of the depression.  The wind shear has blown the thunderstorms north of circulation center.  Some slight intensification may be possible if the wind shear decreases, but the poor organization of the depression will limit any potential strengthening.

If the tropical depression retains its vertical integrity, the southerly winds in the upper levels should push it toward the north.  However, if the wind shear blows the thunderstorms farther north of the low level center of circulation, then the low level center could remain stationary while it spins down.

Patricia Is Strongest East Pacific Hurricane on Record

Hurricane Patricia continued to intensify rapidly during the overnight hours and it is now the strongest hurricane on record for the Eastern North Pacific.  At 11:00 a.m. EDT on Friday the center of Hurricane Patricia was located at latitude 17.6°N and longitude 105.5°W which put it about 125 miles (200 km) southwest of Manzanillo, Mexico.  Patricia was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 200 m.p.h. (320 km) and there were wind gusts to 245 m.p.h. (400 km/h).  The minimum surface pressure was 880 mb.

A Hurricane Warning is in effect for the portion of the coast between Sas Blas and Punta San Telmo, Mexico.  A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Hurricane Patricia has broken a number of records.  The maximum sustained wind speed increased from 85 m.p.h. to 200 m.p.h. between 5:00 a.m. EDT on Thursday and 5:00 a.m. EDT on Friday.  The rate of increase of 115 m.p.h. in 24 hours is the fastest rate of intensification observed in the Eastern Pacific. It exceeds the 100 m.p.h. in 24 hours that occurred in Hurricane Linda in 1997.  Interestingly, 1997 was also an El Nino year.  The minimum surface pressure of 880 mb is the lowest ever recorded in the National Hurricane Center’s Area of Responsibility which includes the Atlantic and Eastern North Pacific Oceans.  It is lower than the 882 recorded when Hurricane Wilma was over the Caribbean Sea in 2005.

Hurricane Patricia is an extremely dangerous hurricane.  It has a Hurricane Intensity Index (HII) of 50.0, a Hurricane Size Index (HSI) of 11.3 and a Hurricane Wind Intensity Size Index (HWISI) of 61.3.  Those indices mean that Patricia will be capable of causing catastrophic regional damage when it reaches the west coast of Mexico north of Manzanillo later on Friday.  Hurricane Patricia will be capable of causing catastrophic wind damage, generating a potentially destructive storm surge near the coast and producing heavy rain and flooding as it moves inland.

Category 5 Hurricane Patricia Threatens West Coast of Mexico

Hurricane Patricia continued to intensify very rapidly on Thursday night and it reached Category 5 on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Thursday the center of Hurricane Patricia was located at latitude 16.2°N and longitude 105.1°W which put it about 200 miles (320 km) south-southwest of Manzanillo, Mexico.  Patricia was moving toward the north-northwest at 10 m.p.h.  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 924 mb.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from San Blas to Punta San Telmo.  A Hurricane Watch and a Tropical Storm Warning is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas.

Hurricane Patricia has a Hurricane Intensity Index (HII) of 35.0.  The Hurricane Size Index (HSI) is 12.4 and the Hurricane Wind Intensity Size Index (HWISI) is 47.4.  Those indices mean that Hurricane Patricia is capable of causing catastrophic regional damage.  Hurricane Patricia is currently about the same size that Hurricane Dennis was before Dennis hit the northern coast of the Gulf of Mexico in 2005.  However, Patricia is stronger than Dennis was at that time.

Hurricane Patricia remains in an environment with warm Sea Surface Temperatures and little vertical wind shear.  Only an eyewall replacement cycle could cause weakening in the short term.  When Hurricane Patricia moves farther north, it will start to encounter upper level winds blowing from the southwest, which will increase the wind shear.  The wind shear could start to weaken Patricia later on Friday.

Hurricane Patricia is moving around the western end of ridge and the hurricane has turned toward the north.  When Patricia encounters the southwesterly winds in the upper levels, it will turn toward the northeast.  On its anticipated track Hurricane Patricia could make landfall on the west coast of Mexico between San Blas and Boca de Apiza on Friday night.  Even though Hurricane Patricia could weaken somewhat before it makes landfall, it will still be a very dangerous hurricane.  Hurricane Patricia poses a major threat to cause significant regional wind damage and a storm surge at the coast.  Heavy rain could produce serious flooding, especially as Patricia moves inland over steeper terrain.

Hurricane Patricia Intensifies Rapidly to Category 4

Hurricane Patricia intensified rapidly on Thursday and it reached Category 4 on the Saffir-Simpson Scale.  The maximum sustained wind speed in Patricia increased from 60 m.p.h. to 130 m.p.h. in 24 hours, which qualified as very rapid intensification.  At 5:00 p.m. EDT on Thursday the center of Hurricane Patricia was located at latitude 15.4°N and longitude 104.6°W which put it about 250 miles (400 km) south of Manzanillo, Mexico.  Patricia was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 953 mb.  The Hurricane Intensity Index (HII) for Patricia was 25.1, the Hurricane Size Index (HSI) was 10.4 and the Hurricane Wind Intensity Size Index was 35.5.  Those indices mean that Patricia is almost as strong and just a little larger than Hurricane Charley was when it hit southwest Florida in 2004.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from San Blas to Punta San Telmo.  It has also issued a Hurricane Watch and a Tropical Storm Warning for the portion of the coast from Punta San Telmo to Lazaro Cardenas.

Patricia is a small hurricane, but it has a very well organized circulation.  A ring of strong thunderstorms surrounds a small, 12 mile (19km), eye (sometimes called a pinhole eye because of the way it looks on satellite images).  Multiple spiral bands are rotating around the core fo the circulation.  Thunderstorms in the core are generating strong upper level divergence in all directions.

Hurricane Patricia remains in a very favorable environment.  It is over water were the Sea Surface Temperature is near 30°C.  An upper level ridge over the top of Patricia is keeping the vertical wind shear to a minimum.  Patricia could intensify further, although if concentric eyewalls develop, then eyewall replacement cycles could produce fluctuations in wind speeds.

Hurricane Patricia is moving around the western end of a ridge that extends from the Gulf of Mexico over Mexico.  When Patricia reaches the end of ridge on Friday, it will turn toward the north.  As the hurricane moves farther north it will encounter westerly winds in the southern end of an upper level trough.  Those winds will turn Hurricane Patricia toward the northeast.

On its anticipated track Hurricane Patricia could approach the west coast of Mexico late on Friday.  It will pose a serious threat to the coast at that time.  Patricia will bring strong winds, heavy rain and a storm surge to the coast.  Very heavy rain could fall as Hurricane Patricia moves inland and serious flooding will be possible, especially in the more mountainous areas of Mexico.  The remnants of Hurricane Patricia could eventually move over parts of Texas and add moisture and rain to that region.

Tropical Storm Patricia Intensifies Quickly and Mexico Issues Warnings

Tropical Storm Patricia reorganized and intensified quickly on Wednesday and the government of Mexico issued warnings for portions of its west coast.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Patricia was located at latitude 13.1°N and longitude 99.5°W, which put it about 265 miles (425 km) south of Acapulco, Mexico and about 515 miles (830 km) southeast of Manzanillo.  Patricia was moving toward the west at 16 m.p.h. (26 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 995 mb.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from Cabo Corrientes to Punta San Telmo.  A Tropical Storm Warning and a Hurricane Watch has been issued for the portion of the coast from Punta San Telmo to Lazaro Cardenas.  A Tropical Storm Watch has been issued for the portion of the coast from Lazaro Cardenas to Tecpan de Galeana.

A NOAA aircraft investigated Tropical Storm Patricia on Wednesday and it found that the center of circulation had reorganized farther west of the remnants of the center that existed on Tuesday.  The new center was west of the northerly low level winds blowing out of the Gulf of Tehuantepec and it was in a more favorable environment.  Thunderstorms are developing near the center of circulation and multiple spiral bands are rotating around the center.

Patricia is moving over water where the Sea Surface Temperature is near 31°C and there is a lot of energy in the upper ocean.  The upper level winds are light and there is not much vertical wind shear.  The lack of wind shear is allowing the thunderstorms near the center to pump out mass and the surface pressure is decreasing.  Patricia will remain a favorable environment until it approaches the west coast of Mexico later this week.  Rapid intensification is likely and Patricia could intensify into a major hurricane before it reaches the coast.

A ridge over the Gulf of Mexico and Mexico is steering Patricia toward the west and that motion is expected to continue for another day or so.  After that time Patricia will reach the western end of the ridge and it will turn toward the north.  On its anticipated track Patricia could be nearing the west coast of Mexico on Friday.

 

Tropical Storm Patricia Forms South of Mexico

A center of circulation began to consolidate inside an area of thunderstorms south of the Gulf of Tehuantepec on Tuesday and the National Hurricane Center designated the system as Tropical Storm Patricia.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Patricia was located at latitude 13.1°N and longitude 95.3°W which put it about 220 miles (355 km) south-southeast of Puerto Escondido, Mexico.  Patricia was moving toward the west-southwest 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 1004 mb.

The circulation of Tropical Storm Patricia was still organizing on Tuesday.  A cluster of thunderstorms formed northeast of the center of circulation earlier on Tuesday, but those storms weakened during recent hours.  A primary rainband extends around the western and southern side of the circulation.  However, there is not much convection northwest of the center of circulation.

Tropical Storm Patricia is over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level ridge surrounds Patricia and it should produce light winds near the tropical storm.  Warm SSTs and little vertical wind shear should allow for intensification.  However, closer to the surface northerly winds blowing across the Gulf of Tehuantepec could be transporting some drier air toward the western side of the circulation.  The drier air could explain the current lack of thunderstorms in that part of Patricia.  Over time the favorable large scale environment should allow for intensification and Patricia could eventually become a hurricane.

A ridge of high pressure north of Patricia is steering the tropical storm toward the west.  That steering motion is expected to continue for another day or so.  When Patricia reaches the western end of the ridge, it will turn toward the north.  Patricia could be approaching the western coast of Mexico on Friday and it could be a hurricane at that time.