Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Potential Tropical Cyclone Fourteen-E Prompts Hurricane Watch for Baja California

The National Hurricane Center is forecasting that a weather system currently designated as Potential Tropical Cyclone Fourteen-E will become a tropical storm and affect Baja California.  The government of Mexico has issued a Hurricane Watch and a Tropical Storm Warning for the portion of the coast from Todos Santo to Los Barriles including Cabo San Lucas.

At 5:00 p.m. EDT on Tuesday the center of Potential Tropical Cyclone Fourteen-E was located at latitude 17.2°N and longitude 107.2°W which put it about 430 miles (695 km) south-southeast of the southern tip of Baja California.  It was moving toward the northwest at 9 m.p.h. (15 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 1006 mb.

The circulation of Potential Tropical Cyclone Fourteen-E is in the early stages of organization.  There is a large counterclockwise circulation over the Eastern North Pacific Ocean west of Mexico.  Numerous showers and thunderstorms are forming within the circulation, but there is no well defined center of circulation.  There are fewer showers and thunderstorms in the eastern portion of the circulation.  An upper level ridge centered over Mexico is generating brisk easterly winds which are blowing over the top of the circulation.  Those winds are causing moderate vertical wind shear and the system has not yet begun to generate much upper level divergence.

Potential Tropical Cyclone Fourteen-E will move through an environment that will be somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  So, there is plenty of energy in the upper ocean to support intensification.  The strength of the upper level winds is forecast to diminish and the wind shear is likely to decrease.  If the wind shear decreases, then the environment will become more favorable for intensification.  Intensification is likely to be slow while the circulation becomes more organized and develops a distinct low level center.  Potential Tropical Cyclone Fourteen-E could become a tropical storm on Wednesday.  It has a chance to intensify to a hurricane on Thursday.

Potential Tropical Cyclone Fourteen-E is moving around the western end of a subtropical ridge.  The ridge is steering the system toward the northwest and a general northwesterly motion is expected to continue for another day or two.  On its anticipated track the center of Potential Tropical Cyclone Fourteen-E could approach the southern part of Baja California by late on Thursday.  It could be a strong tropical storm or a hurricane at that time.  Locally heavy rain falling on the steep terrain of Baja California always creates a risk for flash floods.

Kenneth Rapidly Intensifies Into a Hurricane

One time Tropical Storm Kenneth rapidly intensified into a hurricane on Sunday.  At 5:00 p.m. EDT on Sunday the center of Hurricane Kenneth was located at latitude 16.2°N and longitude 128.4°W which put it about 1290 miles (2075 km) west-southwest of the southern tip of Baja California.  Kenneth was moving toward the west at 14 m.p.h. (22 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 980 mb.

The structure of Hurricane Kenneth improved significantly during the past few hours.  A small circular eye emerged at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds are occurring in this ring of thunderstorms.  Additional bands of showers and thunderstorms intensified south and east of the center.  Thunderstorms near the core of Kenneth were generating strong upper level divergence which was pumping mass away from the hurricane.

Hurricane Kenneth will continue to move through an environment favorable for intensification on Monday.  Kenneth will move over water where the Sea Surface Temperature (SST) is near 28.5°C.  Hurricane Kenneth is moving through a region where the winds in the upper levels are weak and there is not much vertical wind shear.  Hurricane Kenneth could continue to intensify for another 12 to 24 hours.  The speed of the upper level winds could increase in a day or so, and more vertical wind shear would inhibit intensification.  Eventually Hurricane Kenneth will move over cooler SSTs and start to weaken.

Kenneth if moving south of a subtropical ridge which is steering the hurricane toward the west.  The ridge is forecast to continue to steer Kenneth westward for another 12 to 24 hours.  Hurricane Kenneth will turn toward the north when it reaches the western end of the ridge.  On its anticipated track Hurricane Kenneth would pose no direct threat to land.

Tropical Storm Kenneth Develops Southwest of Baja California

Tropical Storm Kenneth developed southwest of Baja California on Friday.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Kenneth was located at latitude 15.0°N and longitude 119.1°W which put it about 810 miles (1305 km) southwest of the southern tip of Baja California.  Kenneth was moving toward the west at 15 m.p.h. (24 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 distinct center of circulation developed in a tropical wave southwest of Baja California on Friday.  Thunderstorms began to form near the center and the National Hurricane Center designated the system as Tropical Storm Kenneth, which was the 11th named tropical storm to form over the Eastern North Pacific during 2017.

A cluster of thunderstorms formed near the core of Tropical Storm Kenneth on Friday.  Even after thunderstorms formed near the core, the circulation of Tropical Storm Kenneth was asymmetrical.  Bands of showers and thunderstorms developed in the western half of the circulation.  The bands in the eastern half of the circulation consisted primarily of showers and low clouds.  Thunderstorms near the core of Kenneth were generating upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Kenneth will move through an environment that will be favorable for intensification during the next several days.  Kenneth will move over water where the Sea Surface Temperature is near 28.5°C.  An upper level ridge to the north of Tropical Storm Kenneth is producing easterly winds which are blowing toward the top of the circulation.  Those winds are producing moderate vertical wind shear which is probably the cause of the asymmetrical circulation of the tropical storm.  Even though there is moderate vertical wind shear, Tropical Storm Kenneth is likely to intensify and it could become a hurricane in a couple of days.

Tropical Storm Kenneth is begin steered toward the west by a subtropical ridge to the north of the tropical storm.  The subtropical ridge will continue to steer Tropical Storm Kenneth toward the west-northwest for another day or two.  When Tropical Storm Kenneth reaches the western end of the subtropical ridge, it will turn more toward the north.

Tropical Storm Jova Develops South of Baja California

A center of circulation developed within the remnants of former Hurricane Franklin on Friday and the National Hurricane Center designated the low pressure system as Tropical Storm Jova.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Jova was located at latitude 19.3°N and longitude 109.8°W which put it 250 miles (400 km) south of the southern tip of Baja California.  Jova was moving toward the west-northwest at 14 m.p.h. (22 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 1003 mb.

The surface center of former Hurricane Franklin was disrupted as it passed over the mountains in Mexico.  However, the middle and upper portions of the circulation crossed the mountains relatively intact.  When the upper parts of the former hurricane emerged over the Eastern North Pacific Ocean, it took nearly a day for the vertical transfer of kinetic energy to spin up a new surface circulation.  Eventually a new surface circulation developed and the National Hurricane Center (NHC) classified the system as Tropical Storm Jova.  Established protocol is that when NHC ceases issuing an advisories on a tropical cyclone, the system is given a new name if it redevelops in a different basin.

The circulation of Tropical Storm Jova is broad, but winds to tropical storm force are occurring primarily in the northeastern quadrant of the circulation.  Most of the thunderstorms are occurring in a band that wraps around the western and southern sides of the center of circulation.  There are fewer thunderstorms in the eastern and northern sides of Tropical Storm Jova,  There is a broad counterclockwise circulation and a distinct center, but the horizontal structure is not well organized.

Tropical Storm Jova will be moving through an environment favorable for intensification during the next 24 hours.  Jova will move over water where the Sea Surface Temperature is near 30°C.  An upper lever ridge over northern Mexico is producing easterly winds which are blowing toward the top of the tropical storm.  Those winds are generating vertical wind shear.  The shear is moderate and it will inhibit intensification.  Tropical Storm is likely to intensify during the next 24 hours, but the broad circulation and vertical wind shear will limit the intensification.  In a day or two Tropical Storm Jova will move over cooler Sea Surface Temperatures and it will start to weaken.

A ridge in the middle levels is steering Tropical Storm Jova toward the west-northwest.  The ridge is expected to steer Tropical Storm Jova toward the west during the next several days.  On its anticipated track Tropical Storm Jova will move farther west of Mexico.

Tropical Depression Eleven-E Forms West of Mexico

Tropical Depression Eleven-E formed west of Mexico on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Depression Eleven-E was located at latitude 17.7°N and longitude 109.2°W which put it about 335 miles (535 km) west-southwest of Manzanillo, Mexico.  The depression was moving toward the west-northwest at 15 m.p.h. (24 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 1009 mb.

The circulation of Tropical Depression Eleven-E is not particularly well organized.  The depression does have a distinct center of circulation which can be seen on visible satellite images.  Most of the showers and thunderstorms are occurring in the western half of the circulation.  The rainbands east of the center of circulation are thin and consist mainly of lighter showers.  The thunderstorms west of the center of circulation are generating only a little upper level divergence which is carrying mass to the west of the depression.

Tropical Depression Eleven-E is in an environment that is only marginally favorable for intensification.  The depression is moving over water where the Sea Surface Temperature is near 28.5°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, an upper level ridge centered over northern Mexico is producing strong northeasterly winds which are blowing across the top of the depression.  Those winds are causing significant vertical wind shear.  The shear is probably the reason for the asymmetrical pattern with all of the thunderstorms in the western half of the circulation.  The shear is forecast to continue and if it does, there will be little or no intensification.  If the shear is less, then some intensification could occur.

Tropical Depression Eleven-E is being steered to the west-northwest by the ridge to its north.  A general west-northwesterly motion is forecast to continue for the next several days.  If the vertical wind shear increases and the depression weakens to a low level system, then winds closer to the surface would steer it more toward the west.  On its anticipated track the depression is expected to move away from Mexico.

Tropical Storms Hilary and Irwin Interact As They Weaken

Tropical Storms Hilary and Irwin started to interact on Thursday as both storms began to weaken.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Hilary was located at latitude 18.3°N and longitude 117.3°W which put it about 575 miles (925 km) west-southwest of the southern tip of Baja California.  Hilary was moving toward the west-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were gust to 85 m.p.h. (140 m.p.h.).  The minimum surface pressure was 992 mb.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Irwin was located at latitude 14.9°N and longitude 124.6°W which put it about 1105 miles (1780 km) west-southwest of the southern tip of Baja California.  Irwin was moving toward the west at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 1000 mb.

Hilary weakened below hurricane intensity on Thursday.  It appeared that the circulation drew in drier more stable air around the northwestern side of the circulation.  The drier air reduced the formation of showers and thunderstorms and the core of the circulation weakened.  At the same time upper level divergence from Tropical Storm Hilary increased the vertical wind shear over Tropical Storm Irwin.  Irwin was over water where the Sea Surface Temperature is near 28.5°C and it was able to extract enough energy from the ocean to maintain most of its intensity.

Tropical Storms Hilary and Irwin will move over water where the Sea Surface Temperature is near 28°C on Friday.  However, the combination of drier, more stable air and vertical wind shear is likely to keep both of the storms from strengthening.  Hilary and Irwin will move over cooler water during the weekend and both tropical storms are likely to weaken when that occurs.

Tropical Storm Hilary is being steering toward the west-northwest by a subtropical high pressure system to the north of the tropical storm.  Hilary is forecast to continue moving toward the west-northwest.  Tropical Storm Hilary is larger than Irwin.  Winds to tropical storm force extend out about 110 miles (180 km) in Tropical Storm Hilary.  Winds to tropical storm force extend out about 70 miles (110 km) in Tropical Storm Irwin.

The centers of the two tropical storms are only about 540 miles (870 km) apart.  When Tropical Storm Hilary passes north of Irwin, Tropical Storm Irwin is forecast to start to revolve around the larger Tropical Storm Hilary.  Irwin is expected to turn toward the north after Tropical Storm Hilary passes by.  Some models are forecasting the that the centers of the two tropical storms will approach each other and the larger Tropical Storm Hilary will eventually absorb Tropical Storm Irwin.

Hurricanes Hilary and Irwin Churn Over Eastern Pacific

Hurricanes Hilary and Irwin continued to churn over the Eastern North Pacific Ocean on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Hilary was located at latitude 16.0°N and longitude 109.8°W which put it about 475 miles (765 km) south of the southern tip of Baja California.  Hilary was moving toward the west-northwest at 12 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 973 mb.

At 11:00 p.m. EDT on Tuesday the center of Hurricane Irwin was located at latitude 16.1°N and longitude 120.9°W which put it about 855 miles (1375 km) west-southwest of the southern tip of Baja California.  Irwin was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 980 mb.

Hilary is the larger and stronger of the two hurricanes.  Hurricane Hilary has a small circular eye surrounded by a ring of strong thunderstorms.  A rainband spirals around the western and southern sides of the core of the circulation.  Thunderstorms in the core are generating strong upper level divergence which is pumping out mass in all directions.  Winds to tropical storm force extend out about 90 miles (145 km) from the center.

Hurricane Irwin has a smaller circulation.  Irwin has a small eye.  Most of the thunderstorms are occurring in the northwestern quadrant of the circulation.  Winds to tropical storm force extend out only about 70 miles (110 km) from the center of circulation.

Hurricane Hilary is moving through a more favorable environment.  Hilary is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear near Hilary.  Hurricane Irwin is moving over water where the Sea Surface Temperature is near 28°C.  An upper level low northwest of Irwin appears to be producing westerly winds which are undercutting the upper level divergence generated by thunderstorms near the core of the hurricane.  Some drier air also seems to wrapping around the eastern side of the circulation.

Hurricane Hilary is moving faster than Hurricane Irwin and Hilary is getting closer to Irwin.  The two hurricanes are expected to interact later this week.  Since Hilary is bigger and stronger than Irwin, Hilary is forecast to become the dominant circulation.  Hurricane Hilary is expected to continue to move in west-northwesterly direction.  When Hilary gets closer to Hurricane Irwin, Irwin is forecast to begin to revolve around Hilary in an interaction called the Fujiwhara effect.  On their anticipated tracks Hurricanes Hilary and Irwin are expected to remain south of the southern tip of Baja California.

Tropical Storm Irwin Forms, Greg Gets Larger, Hilary Strengthens

Tropical Depression Ten-E intensified into Tropical Storm Irwin, the circulation of Tropical Storm Greg increased in size and Tropical Storm Hilary strengthened on Sunday.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Irwin was located at latitude 14.9°N and longitude 116.6°W which put it about 705 miles (1135 km) southwest of the southern tip of Baja California.  Irwin was moving toward the west at 8 m.p.h. (13 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 1003 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Storm Greg was located at latitude 14.4°N and longitude 130.1°W which put it about 1445 miles (2325 km) west-southwest of the southern tip of Baja California.  Greg 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 1001 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Storm Hilary was located at latitude 14.9°N and longitude 102.9°W which put it about 410 miles (660 km) south-southeast of Manzanillo, Mexico.  Hilary was moving toward the west-northwest at 9 m.p.h. (15 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 was 999 mb.

A primary rainband wrapped around the western and southern sides of the center of circulation of Tropical Depression Ten-E and the National Hurricane Center upgraded the system to Tropical Storm Irwin.  Several other bands of showers and thunderstorms were developing over the southern half of the circulation.  There were fewer showers and thunderstorms in the northern half of the circulation.  Thunderstorms near the center of circulation were generating some upper level divergence.

Tropical Storm Irwin will move through an environment that will be somewhat favorable for intensification.  Irwin will move over water where the Sea Surface Temperature (SST) is near 28°C.  An upper level ridge northwest of Irwin are generating northeastern winds which are blowing toward the top of the circulation.  Those winds are generating moderate vertical wind shear and the shear may be the cause of the asymmetric distribution of showers and thunderstorms.  Tropical Storm Irwin could intensify during the next 24 to 48 hours.

The circulation of Tropical Storm Greg grew in size on Sunday.  However, Tropical Storm Greg will move into a less favorable environment during the next several days.  Tropical Storm Greg is over water where the SST is near 28°C, but it will move over cooler water in a day or two.  Greg could intensify in the short term, but it will weaken by midweek.

Tropical Storm Hilary is moving through a very favorable environment.  Hilary is moving over water where the SST is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Storm Hilary could be beginning a period of rapid intensification.  Hilary is forecast to become a hurricane on Monday and it could be a major hurricane later this week.

A subtropical ridge is steering all three tropical storms in a general west-northwesterly direction.  Tropical Storms Greg, Hilary and Irwin are likely to continue to move a little to the north of due west during the next three days.  On its anticipated track Tropical Storm Hilary is expected to remain west of the west coast of Mexico.

Tropical Storm Hilary Develops South of Acapulco

More thunderstorms formed near the center of Tropical Depression Nine-E and the National Hurricane Center upgraded the system to Tropical Storm Hilary.  At 11:00 p.m EDT on Saturday the center of Tropical Storm Hilary was located at latitude 11.5°N and longitude 100.2°W which put it about 375 miles (600 km) south of Acapulco, Mexico.  Hilary was moving toward the west-northwest at 14 m.p.h. (22 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.

The circulation of Tropical Depression Nine-E was not well organized during the past several days as the depression moved over the Eastern North Pacific Ocean.  Thunderstorms began to form close to the center of circulation late on Saturday.  The formation of a core of thunderstorms was evidence of a more organized circulation and the depression was upgraded to Tropical Storm Hilary.  Some bands of showers and thunderstorms also began to develop outside the core of the tropical storm.  The circulation is still somewhat asymmetrical.  More showers and thunderstorms were forming in the northern half of the circulation.  The thunderstorms near the center were starting to generate upper level divergence which is pumping out mass.

Tropical Storm Hilary will be moving through an environment that is favorable for intensification.  Hilary will move over water where the Sea Surface Temperature is near 30°C.  The tropical storm will move through an area where the upper level winds are weak and there will not be a lot of vertical wind shear.  Tropical Storm Hilary should strengthen and it could intensify rapidly if the core of the circulation develops an eye.  Tropical Storm Hilary is likely to become a hurricane and it strengthen into a major hurricane early next week.

Tropical Storm Hilary is moving south of a subtropical ridge which is steering the tropical storm toward the west-northwest.  A general west-northwesterly motion is expected to continue for several more days.  On its anticipated track Tropical Storm Hilary will pass west of the west coast of Mexico.

Tropical Storms Fernanda and Greg Continue West Across the Pacific

Tropical Storms Fernanda and Greg continued to move west across the Pacific Ocean on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Fernanda was located at latitude 18.4°N and longitude 141.4°W which put it about 900 miles (1445 km) east of Hilo, Hawaii.  Fernanda was moving toward the west at 12 m.p.h. (19 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.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Greg was located at latitude 14.3°N and longitude 117.4°W which put it about 770 miles (1240 km) southwest of the southern tip of Baja California.  Greg was moving toward the west at 10 m.p.h. (16 km/h).  The maximum 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 1003 mb.

Tropical Storm Fernanda is moving through an environment that is unfavorable for intensification.  Fernanda is moving over water where the Sea Surface Temperature (SST) is near 26°C.  An upper level trough northeast of Hawaii is producing southwesterly winds which are causing strong vertical wind shear over Fernanda.  Tropical Storm Fernanda has a strong low level circulation but the vertical wind shear will blow the tops off any new thunderstorms that form.  The shear is likely to cause Fernanda to continue to weaken and the low level circulation is likely to gradually spin down.

Tropical Storm Greg did not intensify much on Thursday but recent satellite images seem to indicate that Greg may be getting more organized.  A primary band of showers and thunderstorms has wrapped about two thirds of the way around the eastern and northern sides of the center of circulation.  Upper level outflow from Tropical Storm Fernanda, which is farther west and an upper level low northwest of Greg were generating strong southerly winds which were blowing toward the top of the tropical storm.  Those winds were causing strong vertical wind shear over Tropical Storm Greg.  The upper low appears to be moving farther away from Greg.  Tropical Storm Greg is moving over water where the SST is near 28°C.  If the vertical shear diminishes and the circulation organizes, then there is sufficient energy in the upper ocean to allow Greg to intensify into a hurricane.

A subtropical ridge north of Greg is steering the tropical storm toward the west.  A general westerly motion is expected to continue during the next several days.  Tropical Storm Greg could take a path similar to the track of Tropical Storm Fernanda.