Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Tropical Depression 16E Could Bring Heavy Rain to Southwest U.S.

A center of circulation organized within a cluster of thunderstorms west of Baja California on Sunday and the system was designated Tropical Depression Sixteen-E.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression Sixteen-E (TD16E) was located at latitude 25.0°N and longitude 113.7°W which put it about 90 miles (145 km) west of Cabo San Lazaro, Mexico.  TD16E was moving toward the north-northwest at 14 m.p.h. (22 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 1003 mb.

Tropical Depression 16E has only a few hours before it will move over the central part of Baja California.  Although it is over water where the Sea Surface Temperature is near 27°C little, if any, intensification is expected.  When TD16E crosses Baja California, the terrain and increased vertical wind shear are likely to blow the upper portion of the circulation northward faster than the lower portion of the circulation.  The high clouds could reach parts of the southwestern U.S. within 24 hours.  Moving over mountains will disrupt the lower part of the circulation, but the rotation in the middle levels could persist for several days as it moves northward.

An upper level ridge centered over Texas and an upper level low west of Baja California are combining to steer TD16E northward and that general motion should continue for the next several days.  On its anticipated track TD16E could reach the coast of Baja California near Punta Abreojos in about 12 hours.  It could then move across Baja and the Gulf of California and make a second landfall on the coast west of Hermosillo on Monday morning.  TD16E or its remnants could be approaching southern Arizona later on Monday.  Convection and a flow of moisture associated with TD16E could produce locally heavy rainfall when it is forced to rise of mountains.  It could cause flooding in parts of Baja California, northwestern Mexico and the southwestern U.S.

Linda Rapidly Intensifies Into a Major Hurricane

Hurricane Linda rapidly intensified on Tuesday and it now has a wind speed that qualifies it as a Category 3 Hurricane on the Saffir-Simpson Scale.  This makes Linda the fifth major hurricane in the Eastern North Pacific in 2015.  At 11:00 a.m. EDT on Tuesday the center of Hurricane Linda was located at latitude 21.3°N and longitude 113.9°W which put it about 280 miles (450 km) west-southwest of the southern tip of Baja California.  Linda was moving toward the north-northwest at 14 m.p.h. (22 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 956 mb.

Upper level winds over Linda decreased and the reduction in vertical wind shear allowed it to intensify rapidly during the past 12 hours.  A visible eye and symmetrical eyewall are evidence of a well organized inner core.  Thunderstorms near the center of circulation are generating upper level divergence in all directions which is pumping out mass and causing the pressure to decrease.  Linda could intensify for a few more hours, but it will start to move over much cooler Sea Surface Temperatures (SSTs) later today.  It will be unable to extract enough energy from the cooler water to maintain its intensity and Linda will start to weaken.  As Linda moves farther north, it will also start to encounter stronger upper level winds around the southern portion of an upper level trough near the west coast of the U.S.  Increased vertical wind shear in addition to cooler SSTs will speed up the rate at which Linda weakens.  Since Linda has a large circulation, it could take longer for it to spin down.

An upper level ridge over Mexico is steering Linda toward the north-northwest and that general motion is expected to continue as long as it maintains tall thunderstorms.  When Linda weakens to a tropical storm over cooler water, the circulation will not extend as high in the atmosphere.  After that time Linda will be steered more toward the west by winds lower in the atmosphere.  On its anticipated track Linda will move parallel to the coast of Baja California for several days before turning away from the coast later this week.

Tropical Storm Linda Forms South of Baja California

A spiral band continued to wrap more tightly around the center of circulation inside a large low pressure system west of Mexico on Sunday and the National Hurricane Center designated the system as Tropical Storm Linda.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Linda was located at latitude 14.1°N and longitude 109.0°W which put it about 610 miles (980 km) south of the southern tip of Baja California.  Linda was moving toward the northwest at 12 m.p.h. (19 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 1000 mb.

The circulation in Tropical Storm Linda is well organized.  There is one main spiral rainband and multiple outer rainbands.  Outside of the core of the circulation there are fewer thunderstorms east of the center, which could mean that some drier air is being pulled into that part of the storm.  Thunderstorms in the core are generating upper level divergence.  Linda is over water where the Sea Surface Temperatures (SSTs) are above 29°C.  An upper level trough near the west coast of the U.S. and an upper level ridge over northern Mexico are combining to create an outflow channel to the northeast, which is enhancing the flow of mass away from the tropical storm.  There is little vertical wind shear over the top of Linda and the environment is favorable for further intensification.  A period of rapid intensification is possible and Linda is likely to become a hurricane.  Eventually, when it moves farther north, Linda will move into an area of cooler SSTs and more vertical wind shear, which will cause it to weaken.

Linda appears to be moving a little more toward the west-northwest this afternoon.  The upper level ridge over northern Mexico is expected to steer it in a generally northwesterly direction during the next few days.  On its anticipated track, Linda would move west of Baja California during the middle of next week.

Tropical Storm Kevin Forms Southwest of Baja California

Vertical wind shear decreased enough on Thursday to allow more thunderstorms to develop near the center of Tropical Depression 14E and the National Hurricane Center upgraded it to Tropical Storm Kevin.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Kevin was located at latitude 17.9°N and longitude 115.6°W which put it about 505 miles (815 km) southwest of the southern tip of Baja California.  Kevin was moving toward the north at 6 m.p.h. (9 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1000 mb.

Tropical Storm Kevin is a small tropical cyclone.  Winds to tropical storm force only extend out about 70 miles (115 km) from the center of circulation.  There is one short spiral band wrapping around the northwest side of the center and another short band wrapping around the southwest side of the center.  There are not many thunderstorms in the eastern half of the circulation.  Kevin is over water where the Sea Surface Temperature (SST) is near 29°C.  However, a large, high amplitude upper level trough along the west coast of the U.S. is generating moderate southwesterly winds over the top of Kevin.  The vertical wind shear inhibited the development of Kevin, but the shear seems to have lessened today and the circulation in the tropical storm has consolidated around the center.  Thunderstorms near the center of Kevin are generating upper level divergence over a small area.

As Kevin moves farther north it will move over cooler SSTs.   When it gets north of latitude 22°N, Kevin will move over SSTs cooler than 26°C.  If the vertical wind shear remains moderate, Kevin could intensify further during the next 24 to 48 hours.  After about two days, the tropical storm will move over cooler SSTs and into an area with more vertical wind shear.  At that point Kevin is likely to start to spin down.

A ridge over Mexico is steering Kevin toward the north and that general motion is expected to continue for another day or two.  When Kevin moves over cooler SSTs, the thunderstorms will not be as tall and it will be steered by the winds lower in the atmosphere.  Those winds could push Kevin more toward the west during the weekend.

Trio of Cat. 4 Hurricanes Churn Across the Pacific

A trio of powerful Category 4 hurricanes on the Saffir-Simpson Scale churned across the Central and Eastern North Pacific on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Ignacio was located at latitude 17.0°N and longitude 147.6°W which put it about 525 miles (845 km) east-southeast of Hilo, Hawaii.  Ignacio was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 951 mb.

At 11:00 p.m. EDT on Saturday the center of Hurricane Jimena was located at latitude 13.3°N and longitude 127.5°W which put it about 1330 miles (2140 km) west-southwest of the southern tip of Baja California.  Jimena was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 945 mb.

At 11:00 p.m. EDT on Saturday the center of Hurricane Kilo was located at latitude 18.4°N and longitude 176.2°W which put it about 680 miles (1095 km) south of Midway Island.  Kilo was moving toward the west-northwest at 9 m.p.h.  The maximum sustained wind speed was 135 m.p.h. (215 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 948 mb.

Ignacio is the only one of the three powerful hurricane to pose an imminent threat to land.  On its anticipated track Ignacio could be northeast of the Big Island of Hawaii in about 48 hours.  Tropical Storm Watches have been issued for Hawaii County and Maui County including the islands of Maui, Molokai, Lanai and Kahoolawe.  An upper level trough passing north of Hawaii will cause westerly winds and increasing vertical wind shear over Ignacio as it moves closer to Hawaii.  Ignacio should weaken but it could still be a hurricane when it makes its closest approach to Hawaii.  Given the size of the circulation around Ignacio, Tropical Storm Watches were issued for some of the islands.

Jimena may be the most well organized of the three hurricanes.  It has concentric eyewalls and a very symmetrical structure.  Eyewall replacement cycles will cause fluctuations in the intensity of Jimena.  However, it is in a very favorable environment and it could reach Category 5 intensity at some point.  Fortunately, Jimena is about 1500 miles (2420 km) east of Ignacio and it is a long way from any land area.

After days when strong vertical wind shear kept Kilo a weak disorganized tropical depression, it intensified very rapidly during the past 48 hours.  Kilo is over warm Sea Surface Temperatures  and it could intensify a little more.  Kilo is not currently a threat to any land.

Hurricanes Ignacio and Jimena Heading West

Hurricanes Ignacio and Jimena are heading steadily westward over the Pacific Ocean.  At 5:00 p.m. EDT on Friday the center of Hurricane Ignacio was located at latitude 14.6°N and longitude 144.5°W which put it about 785 miles (1260 km) east-southeast of Hilo, Hawaii.  Ignacio was moving toward the northwest at 8 m.p.h. (13 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 982 mb.  At 5:00 p.m. EDT on Friday the center of Hurricane Jimena was located at latitude 12.3°N and longitude 123.1°W which put it about 1135 miles (1825 km) southwest of the southern tip of Baja California.  Jimena was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 972 mb.

Hurricane Ignacio has remained in a relatively steady state during much of today.  It is moving over water where the Sea Surface Temperature is near 29°C, but an upper level trough near Hawaii is causing some vertical wind shear.  Recent satellite images indicate that an eye may be forming and the core of Ignacio’s circulation is becoming better organized.  Ignacio could strengthen during the next day or so before it moves farther west and the vertical wind shear increases.  A subtropical ridge is steering Ignacio toward the west-northwest and that general motion is expected to continue during the weekend.  Ignacio could be approaching the Big Island of Hawaii in about three days.

Hurricane Jimena intensified rapidly on Friday and it is on the verge of becoming a major hurricane.  It has a very well formed eye with a ring of strong thunderstorms around it.  The upper level winds near Jimena are light and upper level divergence is pumping out mass in all directions.  Jimena is over water where the Sea Surface Temperatures are between 29°C and 30°C and further intensification is likely.  Eye replacement cycles could cause periodic fluctuations in the intensity of Jimena.  Jimena is about 1400 miles (2260 km) east of Ignacio and it could eventually move over some cooler water stirred to the surface by the other hurricane.  The subtropical ridge is also steering JImena toward the west and that motion is expected to continue for the next few days.

Ignacio Becomes a Hurricane

The core of Tropical Storm Ignacio organized rapidly on Wednesday and it was upgraded to hurricane status by the National Hurricane Center.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Ignacio was located at latitude 12.2°N and longitude 137.5°W which put it about 1275 miles (2055 km) east-southeast of Hilo, Hawaii.  Ignacio was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 992 mb.

A primary rainband wrapped completely around the center of Ignacio and a large eye cleared in the middle of the circulation.   Strong thunderstorms surround the eye in a well formed eyewall.  Other bands of thunderstorms are spiraling around the core of Ignacio.  The upper level winds lessened and the strong convection in the core of Ignacio produced upper level divergence.  The divergence pumped out mass and the surface pressure decreased.  Ignacio is over warm Sea Surface Temperatures.  The environment is favorable for intensification and a period of rapid intensification is possible.  Ignacio could become a major hurricane as it moves across the Central Pacific.

A subtropical ridge is steering Ignacio toward the west.  The ridge is expected to steer the hurricane in a generally west-northwesterly direction during the next few days.  On its anticipated track Ignacio could approach the Big Island of Hawaii in about five days.

Tropical Storm Ignacio Forms Well East of Hawaii

The circulation within a cluster of thunderstorms well to the east of Hawaii became more well organized and the system was classified as Tropical Storm Ignacio.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Ignacio was located at latitude 12.3°N and longitude 133.4°W which put it about 1525 miles (2455 km) east-southeast of Hilo, Hawaii.  Ignacio was  moving toward the west at 6 m.p.h. (9 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 1003 mb.

The circulation of Tropical Storm Ignacio is still organizing.  Some thunderstorms are located within the core of the tropical storm and more storms are forming in bands around the circulation.  Ignacio is moving over water where the Sea Surface Temperature is near 29°C.  Southeasterly winds in the upper levels are causing some vertical wind shear.  However, some upper level divergence appears to be occurring on the northern side of the circulation.  The environment appears to favor intensification and a period of rapid intensification could occur if an eye starts to form in the core of the tropical storm.

A subtropical ridge is steering Ignacio toward the west and that general motion is expected to continue during the next few days.  On its anticipated track Ignacio would be southeast of Hawaii this weekend.

Kilo and Loke Weaken to Tropical Depressions

Both Tropical Storms Kilo and Loke weakened on Saturday and were downgraded to tropical depression status.  At 5:00 p.m. EDT on Saturday the center of Tropical Depression Kilo was located at latitude 14.2°N and longitude 159.4°W which put it about 500 miles (805 km) south-southwest of Honolulu, Hawaii.  Kilo 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 m.p.h.).  The minimum surface pressure was 1005 mb.

At 5:00 p.m. EDT on Saturday the center of Tropical Depression Loke was located at latitude 18.1°N and longitude 178.6°W which put it about 700 miles (1130 km) south of Midway Island.  Loke was moving toward the northwest at 8 m.p.h.  The maximum sustained wind speed was 35 m.p.h. (55 km/) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1003 mb.

Kilo appeared to be affected by vertical wind shear for much of Saturday.  A reconnaissance aircraft had a difficult time trying to find a surface circulation center and the spiral bands were not well developed.  Upper level easterly winds appeared to be pushing the tops of thunderstorms west of the low level circulation and inhibiting the formation of a warm core in the upper levels.  Recent satellite imagery suggests that more thunderstorms could be forming closer to the center of Kilo.  The vertical wind shear is forecast to decrease and Kilo could strengthen during the next few days.  A subtropical ridge is steering Kilo westward, but the ridge is expected to weaken and the steering currents could become weaker on Sunday.  Eventually, an upper level trough approaching from the northwest is forecast to pull Kilo toward the northeast early next week.

Loke appears to be very well organized for a tropical depression.  A primary rainband wraps around the western and southern side of the center of circulation and there appears to be about three quarters of an eyewall trying to form around the center.  The thunderstorms in the band are generating upper level divergence.  Loke is over warm Sea Surface Temperatures.  However, an upper level trough northwest of Loke is generating some southwesterly winds that are creating some vertical wind shear and are inhibiting upper level divergence south of the center of circulation.  That same upper level trough is expected to steer Loke toward the north-northeast during the next few days.  On it anticipated track Loke could be near Midway Island in about 60 hours.

Tropical Storms Kilo and Loke Form Over the Central Pacific

Two tropical storms formed over the Central Pacific Ocean on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Kilo was located at latitude 13.0°N and longitude 153.3°W which put it about 480 miles (770 km) south-southeast of Hilo, Hawaii.  Kilo was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.

At 5:00 p.m. EDT on Friday the center of Tropical Storm Loke was located at latitude 16.4°N and longitude 177.2°W which put it about 815 miles (1310 km) south of Midway Island.  Loke was moving toward the north at 6 m.p.h. (9 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 55 m.p.h. (90 km/h).  The minimum surface pressure was 1000 mb.

Tropical Storm Kilo is not very well organized at the present time.  Strong easterly winds in the upper levels are blowing the tops off of the thunderstorms and the vertical wind shear is keeping Kilo from intensifying.  If the shear decreases as some numerical models forecast, then Kilo could intensify.  On the other hand, if the shear stays strong, then Kilo could weaken to a tropical depression.  If Kilo intensifies as some models suggest, then it could be pushed toward the western Hawaiian Islands.  However, if Kilo stays weaker, then winds lower in the atmosphere could steer more toward the west and keep it south of Hawaii.

Tropical Storm Loke is better organized, although most of the stronger thunderstorms are north of the center.  An upper level trough northwest of Loke could be creating some southwesterly winds around the tropical storm.  Although the vertical wind shear may be slowing the rate of intensification, Loke does appear to be getting stronger.  The upper level trough is expected to steer Loke toward the north and it could approach Midway Island in four or five days.  Loke could be a hurricane at that time.