Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Tropical Storm Javier Near Southern Tip of Baja California

Tropical Storm Javier moved slowly toward the southern tip of Baja California on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Javier was located at latitude 22.5°N and longitude 109.7°W which put it about 30 miles (50 km) south-southeast of Cabo San Lucas, Mexico.  Javier was moving toward the northwest at 5 m.p.h. (8 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.

The government of Mexico has discontinued all Hurricane Warnings and Watches.  A Tropical Storm Warning remains in effect for the portion of the coast from San Evaristo to Cabo San Lazaro.  A Tropical Storm Watch is in effect for the portion of the coast from San Evaristo to Loreto and from Cabo San Lazaro to Puerto San Andresito.

Javier is a small tropical storm.  Winds to tropical storm force only extend out about 60 miles (95 km) from the center of circulation.  The circulation of Tropical Storm Javier weakened during the past few hours.  Data from a NOAA Hurricane Hunter Research aircraft indicated that drier air in the middle levels had been pulled into the circulation of Javier.  The ingestion of the drier air weakened many of the thunderstorms and the wind speed decreased.  In addition an upper level ridge over northern Mexico appears to be causing easterly winds to blow across the top of Javier.  The vertical wind shear is tilting the circulation and the upper levels of Javier are tilted to the west of the surface center.

Tropical Storm Javier is in an environment that is not favorable for intensification.  Javier is over water where the Sea Surface Temperature is near 28°C, but the water west of Baja California is cooler.  The tropical storm is ingesting drier air and it is encountering vertical wind shear.  The proximity of Tropical Storm Javier to Baja California may also cause the terrain to disrupt the circulation.  Tropical Storm Javier may be able to maintain its intensity at times, but it is likely to weaken during the next several days.

Tropical Storm Javier is moving around the western end of a ridge over Mexico which has been steering it toward the northwest.  Since the thunderstorms in Javier are not as tall, it is being steered by winds lower in the atmosphere and those steering currents appear to be weaker.  As a result, Tropical Storm Javier moved much more slowly on Monday night.  When a tropical cyclone moves very close to Baja California, the terrain has an impact on the structure of the storm and its ultimate motion.  It is possible that the upper and lower portions of Tropical Storm Javier’s circulation could be sheared apart.  If that happens, the lower portion of the circulation could drift slowly along the west coast of Baja California.  The middle and upper portions of the circulation could be pulled north into the southwestern U.S. by an upper level trough off the west coast of the U.S.

The primary risks posed by Tropical Storm Javier are locally heavy rainfall and flash floods.  Steep terrain in parts of Baja California exacerbate the flood risk in those areas.  It is possible that some moisture associated with Tropical Storm Javier could be pulled into the southwestern U.S. later this week.  If that happens, the moisture will enhance rainfall over parts of Arizona and surrounding states.

Tropical Storm Javier Forms and Heads for Baja California

Tropical Storm Javier formed west of Mexico on Sunday and headed for Baja California.  At 11:00 p.m. EDT the government of Mexico issued Hurricane Warnings and Hurricane Watches for part of Baja California.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Javier was located at latitude 20.6°N and longitude 107.7°W which put it about 210 miles (340 km) southeast of Cabo San Lucas, Mexico.  Javier was moving to the northwest at 13 m.p.h. (20 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.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from Cabo San Lucas to Todos Santos.  A Hurricane Watch and a Tropical Storm Warning has been issued for the portions of the coast from Todos Santos to Cabo San Lazaro and from Cabo San Lucas to Los Barriles.  A Tropical Storm Warning has been issued for the portion of the coast from Los Barriles to San Evaristo.  A Tropical Storm Watch has been issued for the portion of the coast from San Evaristo to Loreto.

Part of the middle and upper level structure associate with Tropical Storm Earl moved westward across Mexico and interacted with a surface trough of low pressure near the west coast of Mexico.  The middle and upper rotation was transported to the surface and a small low pressure system formed southwest of Manzanillo, Mexico.  The system was originally designated Tropical Depression 11-E early on Sunday.  A weather station at Manzanillo reported a wind from the southeast at 46 m.p.h. (74 km/h) at 11:00 a.m. EDT on Sunday and the National Hurricane Center upgraded the system to Tropical Storm Javier.

Javier is a small tropical storm and the circulation is still organizing.  The tropical storm force winds are occurring within 100 miles (160 km) of the center of Tropical Storm Javier.  Most of the thunderstorms are in the western western half of the tropical storm and many are located close to the center of circulation.  The thunderstorms near the center of Javier are generating upper level divergence but it is primarily moving away to the west of the tropical storm.

Tropical Storm Javier is in an environment that is somewhat favorable for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level ridge centered near Texas is producing easterly winds that are blowing over the top of Javier.  The easterly winds are causing some vertical wind shear and they are inhibiting upper level divergence to the east of Javier.  Tropical Storm Jaiver may also be drawing in some drier air from Mexico, since it is close to the coast.  The wind shear and drier air will inhibit the rate of intensification, but Tropical Storm Javier should be able to extract enough energy from the warm SSTs to intensify.

Tropical Storm Javier is moving around the western end of the upper level ridge centered near Texas.  Clockwise flow around that ridge is steering Javier toward the west-northwest.  As Javier nears the western end of the ridge, it will turn more toward the north.  On its anticipated track Tropical Storm Javier could approach the southern tip of Baja California by late Monday.

Tropical Storm Javier could do some wind damage, but the primary risks will be locally heavy rainfall and flash flooding.  Tropical Storm Javier could increase the flow of moist air over the southwestern U.S. later this week and it could enhance the normal August thunderstorm activity in that region.

Weaker Tropical Storm Darby Makes Landfall on Big Island of Hawaii

A weakened Tropical Storm Darby made landfall on the southern end of the Big Island of Hawaii on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Darby was located at latitude 19.3°N and longitude 155.8°W which put it about 195 miles (310 km) southeast of Honolulu, Hawaii.  Darby was moving toward the west 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 1006 mb.

Tropical Storm Warnings are in effect for Oahu, Hawaii County, Maui County including Maui, Molokai, Lanai and Kahoolawe, and Kauai County including Kauai and Niihau.

Air Force Reserve Hurricane Hunters investigated Tropical Storm Darby on Saturday and documented its weaker, less well organized structure.  Darby does not have a well formed inner core and the center of low pressure is broad and diffuse.  Most of the rain and thunderstorms are occurring south of the center of circulation.  The remnant of the primary spiral band consists of a short arc of thunderstorms southeast of the center of circulation.  There are few showers in the northern part of the circulation.

Tropical Storm Darby is moving toward water where the Sea Surface Temperature is near 28°C.  However, the center is moving over the Big Island of Hawaii, which will further disrupt the circulation.  Drier, more stable air is north of Darby and that will limit the potential for further convection.  If Darby retains sufficient organization after it moves back over water, it could continue as a tropical storm for another day or so.  However, if passage over land completely destroys the inner core, then Darby could dissipate during the next several days.

Tropical Storm Darby is nearing the western end of a subtropical ridge that has been steering toward the west.  When Darby reaches the end of the ridge, it is expected to turn more toward the northwest, which is why tropical storm warnings are in effect for a number of the Hawaiian Islands.   Locally heavy rain and the potential for flash flooding are the primary threats from Tropical Storm Darby.

Tropical Storm Darby Closes In on Hawaii

Tropical Storm Darby moved closer to Hawaii on Friday and the Tropical Storm Watches were upgraded to Tropical Storm Warnings.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Darby was located at latitude 18.7°N and longitude 152.1°W which put it about 205 miles (335 km) east-southeast of Hilo, Hawaii.  Darby was moving toward the west at 12 m.p.h. (19 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 1000 mb.

Tropical Storm Warnings are in effect for Hawaii County and Maui County including Maui, Molokai, Lanai and Kahoolawe,  A Tropical Storm Watch has been issued for Maui.

An Air Force Reserve Hurricane Hunter reconnaissance aircraft investigated Tropical Storm Darby on Friday and provided data from inside the tropical storm.  Darby has an asymmetrical structure.  A primary rainband wraps around the western side of the tropical storm and most of the thunderstorms are west of the center of circulation.  An upper level ridge west of Hawaii is generating northeasterly winds which are blowing over the top of Tropical Storm Darby.  The vertical wind shear caused by the upper level ridge is contributing to the asymmetrical structure of the circulation.  The thunderstorms in the primary rainband are generating some upper level divergence.  Most of the stronger winds are occurring in the northern half of the circulation.

Darby is moving through an environment that is marginal for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 27.5°C.  However, the vertical wind shear is inhibiting the upper level divergence to the northeast.  The effects of warm SSTs and moderate upper level divergence appear to be offsetting each other and the intensity of Tropical Storm Darby did not change much on Friday.  As Darby moves farther west, the SSTs will start to decrease and the vertical wind shear will increase.  The more hostile environment is expected to cause Darby to weaken during the next few days.

A subtropical ridge north of Darby is steering the tropical storm toward the west.  Darby is moving near the western end of the ridge and it is expected to turn more toward the northwest during the weekend.  On its expected track Tropical Storm Darby is forecast to move near the Big Island of Hawaii on Saturday.  If Darby makes the expected turn toward the northwest, it could affect much of Hawaii.

Tropical Storm Darby will bring strong winds and higher than normal surf to Hawaii.  However, the greatest risk will be caused by winds flowing up slopes, which will produce locally heavy rain and the chance for flash floods.

Tropical Storm Darby Moves Closer to Hawaii and Watches Issued

Tropical Storm Darby moved closed to Hawaii on Thursday and Tropical Storm Watches were issued for some of the islands.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Darby was located at latitude 18.9°N and longitude 147.5°W which put it about 500 miles (800 km) east of Hilo, Hawaii.  Darby was moving toward the west at 13 m.p.h. (20 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 Watch has been issued for Hawaii County and Maui County including the islands of Maui, Molokai, Lanai, and Kahoolawe.

Tropical Storm Darby is maintaining its structure.  A primary rainband wraps around the north and west sides of the center of circulation.  Strong thunderstorms continue to develop close to the center of circulation.  Those thunderstorms are producing upper level divergence.  Darby is a small tropical storm.  Winds to tropical storm force extend out about 100 miles (160 km) on the north side of the circulation, but they only extend out about 50 miles (80 km) to south of the center.

Tropical Storm Darby is moving through an environment that is marginal for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 27°C.  So, there is enough energy in the upper ocean to support a tropical cyclones.  However, an upper level ridge centered west of Hawaii is generating northeasterly winds which are blowing over the western half of the circulation.  The moderate vertical wind shear is inhibiting intensification.  Darby maintained its intensity on Thursday as the positive and negative environmental factors effectively balanced each other out.  Darby could continue to maintain its intensity for several more days until it moves over cooler SSTs and into a region of stronger vertical wind shear.

A subtropical ridge north of Darby is steering the tropical storm toward the west.  That general motion is forecast to continue for another 36 hours.  On its anticipated track Tropical Storm Darby could approach the Big Island of Hawaii in about 36 hours.  It could bring tropical storm force winds to that island.  In addition Darby could cause heavy rain and flash flooding in locations where the wind blows up the slopes on the islands.

Tropical Storm Frank and Tropical Depression 08E Form

The National Hurricane Center designated two new systems over the Eastern North Pacific Ocean as tropical cyclones on Thursday afternoon.  Tropical Storm Frank was the sixth tropical storm to form over the Eastern North Pacific during the month of July.  The record for tropical storms forming in July is seven.  If Tropical Depression 08E intensifies into a tropical storm then 2016 will tie the record for the most tropical storms to form over the Eastern Pacific during July.

At 5:00 p.m. EDT on Thursday the center of Tropical Storm Frank was located at latitude 14.9°N and longitude 104.0°W which put it about 675 miles (1085 km) southeast of the southern tip of Baja California.  Frank was moving toward the northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1005 mb.

At 5:00 p.m. EDT on Thursday the center of Tropical Depression 08E was located at latitude 10.8°N and longitude 114.0°W which put it about 880 miles (1415 km) south-southwest of the southern tip of Baja California.  The depression was moving toward the west-northwest at 12 m.p.h. (19 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. (70 km/h).  The minimum surface pressure was 1006 mb.

Tropical Storm Frank is the larger and better organized system.  A primary rainband wraps about three-quarters of way around the western side of the center of circulation.  Additional rainbands are spiraling around the outer portion of Frank.  Thunderstorms near the center of circulation are generating upper level outflow which is pumping out mass in all directions.

The circulation of Tropical Depression 08E is smaller and less well organized.  A primary rainband wraps about half way around the western side of the center of circulation.  Other partial rainbands are evident, but most of the thunderstorms are occurring in the western half of the circulation.  If looks like some of the upper level outflow from Tropical Storm Frank could be causing vertical wind shear over Tropical Depression 08E.

The environment around Tropical Storm Frank is favorable for intensification.  Frank is moving over water where the Sea Surface Temperature is near 29°C.  In addition, Tropical Storm Frank appears to be located beneath an upper level anticyclone, which is enhancing the upper level divergence.  Frank is likely to intensify during the next several days and it could intensify rapidly once an inner core forms around an eye.

The environment around Tropical Depression 08E is not as favorable.  It is over water the Sea Surface Temperature is near 28°C.  Upper level outflow from the anticyclone over Tropical Storm Frank is generating easterly winds and moderate vertical wind shear over the depression.  If Tropical Depression 08E and Tropical Storm Frank move farther apart, then the shear could decrease and the depression could strengthen.

A subtropical ridge is steering both Tropical Storm Frank and Tropical Depression 08E toward the west-northwest.  However, a weaker area in the ridge is forecast to develop northwest of Frank and that could allow the tropical storm to move on a more northwesterly track.  On its anticipated track Tropical Storm Frank could move near the southern tip of Baja California on Sunday.

Tropical Storm Estelle Forms As Hurricane Darby Nears Peak Intensity

Tropical Storm Estelle developed late Friday over the Eastern North Pacific as Hurricane Darby neared its peak intensity farther west.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Estelle was located at latitude 15.2°N and longitude 108.3°W which put it about 370 miles (600 km) southwest of Manzanillo, Mexico.  Estelle was moving toward the west-northwest at 12 m.p.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.  Estelle is the fifth tropical storm to form over the Eastern North Pacific during the month of July.

Meanwhile, about 950 miles west of Estelle, Hurricane Darby neared its peak intensity.  At 11:00 p.m. EDT on Friday the center of Hurricane Darby was located at latitude 17.3°N and longitude 122.1°W which put it about 880 miles (1415 km) west-southwest of the southern tip of Baja California.  Darby was moving toward the west-northwest at 9 m.p.h.  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 972 mb.

The large circulation around Tropical Storm Estelle is still organizing.  A primary rainband is wrapping around the western side of the center.  Several spiral bands of thunderstorms are forming farther away from the core of the tropical storm.  Storms near the center are beginning to produce upper level divergence, but it is not currently well developed.

The environment around Estelle is favorable for gradual intensification.  Estelle is moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Estelle is generating easterly winds which are blowing over the top of the tropical storm.  There is enough vertical wind shear to slow the rate of intensification, but the shear is probably not strong enough to keep Estelle from intensifying.  Storms like Estelle with large initial circulations can intensify slowly as a tighter core develops within the larger circulation.

Hurricane Darby is a well formed mature hurricane.  It has a well developed eye surrounded by a narrow ring of strong thunderstorms.  Several spiral bands are rotating around the core of Darby.  The thunderstorms near the center of circulation are generating upper level divergence which is pumping out mass in all directions.

Hurricane Darby is probably close to its peak intensity.  It is moving over water where the Sea Surface Temperature is near 27°C and Darby will be moving over cooler water during the next few days.  There is not much vertical wind shear, and Darby may have a chance to intensify during the next 12 to 24 hours.  However, Darby will reach cooler water in about a day and then the hurricane will being to weaken.

A subtropical ridge located north of Hurricane Darby and Tropical Storm Estelle is expected to steer both cyclones toward the west during the next few days.

Tropical Storm Darby Intensifies as Hurricane Celia Weakens

Tropical Storm Darby intensified on Tuesday as it moved in the trail of weakening Hurricane Celia.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Darby was located at latitude 15.4°N and longitude 110.4°W which put it about 520 miles (835 km) south of the southern tip of Baja California.  Darby was moving toward the west at 10 m.p.h. (16 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 1000 mb.

Farther west Hurricane Celia continued to weaken slowly on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Celia was located at latitude 18.0°N and longitude 110.4°W which put it about 1360 miles (2190 km) west of the southern tip of Baja California.  Celia was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 986 mb.

More thunderstorms developed near the center of Tropical Storm Darby on Tuesday.  However, most of the stronger thunderstorms were southwest of the center of circulation.  An upper level ridge near the west coast of Mexico was producing northeasterly winds which are blowing over the top of the tropical storm.  The vertical wind shear caused the asymmetric distribution of convection.  Despite the vertical wind shear the circulation in the lower levels was well developed.

Tropical Storm Darby is over water where the Sea Surface Temperature is near 30°C and Darby is expected to intensify into a hurricane.

Hurricane Celia is moving over water where the Sea Surface Temperature is near 25°C.  Since the hurricane is extracting less energy from the ocean, the thunderstorms are not as tall and Celia is slowly weakening.  The hurricane is in an area where the vertical wind shear is minimal and so the weakening trend is likely to occur at a slower rate than normal.

A subtropical ridge north of the Celia and Darby is steering the two tropical storms toward the west and that general motion is expected to continue for the next few days.

Hurricane Celia Develops West of Mexico

The next in a series of tropical systems over the Eastern North Pacific Ocean developed into Hurricane Celia on Sunday.  At 11:00 p.m. EDT on Sunday the center of Hurricane Celia was located at latitude 15.0°N and longitude 123.5°W which put it about 1040 miles (1675 km) west-southwest of the southern tip of Baja California.  Celia was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 988 mb.

The circulation of Hurricane Celia is well developed.  A primary spiral band loops around the center of circulation and a small eye is apparent intermittently on satellite imagery.  The strongest winds are occurring within 20 miles (30 km) of the center of circulation.  Although there are numerous thunderstorms in the core of Hurricane Celia, they are not as tall as one might expect.  It could be that slightly cooler water was mixed to the surface by Hurricane Blas and the cooler water is causing the thunderstorms to reach their Equilibrium Level at a lower height.  In spite of the shorter thunderstorms, the circulation is generating upper level divergence in all directions.

The environment is favorable for intensification.  Hurricane Celia is moving over water where the Sea Surface Temperature (SST) is near 28°C.  The winds in the upper levels are weak and there is not much vertical wind shear.  Celia could intensify while is remains over warmer SSTs.  The hurricane will start to move over cooler SSTs in about another 24 hours, which will contribute to a less favorable environment.

A subtropical high pressure system north of Celia is steering the hurricane toward the west and that general motion is expected to continue during the next few days.  On its anticipated track Hurricane Celia will continue to move farther away from Mexico.

Blas Strengthens to Cat. 4 Hurricane

Hurricane Blas strengthened rapidly Tuesday to a Category 4 hurricane on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Thursday the center of Hurricane Blas was located at latitude 14.4°N and longitude 121.7°W which put it about 970 miles (1560 km) west-southwest of the southern tip of Baja California.  Blas was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 947 mb.

The Hurricane Intensity Index (HII) for Blas was 28.2.  The Hurricane Size Index (HSI) was 12.2 and the Hurricane Wind Intensity Size Index (HWISI) was 40.4.

The circulation of Hurricane Blas is fairly symmetrical and well organized, although many of the stronger thunderstorms are occurring in the southeastern quadrant.  Blas has a clear eye which is surrounded by a ring of strong thunderstorms.  Those storms generated upper level divergence which pumped out a lot of mass in all directions and allowed the pressure to decrease rapidly on Tuesday.

Hurricane Blas is in an environment that is favorable for strong hurricanes.  It is moving over water where the Sea Surface Temperature is near 29°C.  The winds in the upper levels are light and there is not much vertical wind shear.  Hurricane Blas could get stronger on Wednesday.  However, eyewall replacement cycles sometimes occur in strong hurricanes.  When an eyewall replacement cycle occurs, it can bring an end to a period of intensification.

A ridge of high pressure located north of Blas is steering the hurricane toward the west and that motion is expected to continue for several more days.  Hurricane Blas continues to move farther away from Mexico.