Tag Archives: Tropical Storm Lowell

Tropical Storm Norbert Develops Southwest of Baja California

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Tropical Storm Norbert developed over the Eastern North Pacific Ocean southwest of Baja California on Wednesday night.  At 5:00 a.m. EDT on Thursday the center of Tropical Storm Norbert was located at latitude 16.4°N and longitude 117.9°W which put the center about 685 miles (1105 km) southwest of the southern tip of Baja California.  Norbert was moving toward the west at 13 m.p.h. (21 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.

A low pressure system over the Eastern North Pacific Ocean southwest of Baja California strengthened on Wednesday night and the U.S. National Hurricane Center designated the system as Tropical Storm Norbert.

The distribution of thunderstorms in Tropical Storm Norbert was asymmetrical.  Thunderstorms were occurring in bands in the eastern side of Norbert’s circulation.  Bands in the western side of Tropical Storm Norbert consisted primarily of showers and lower clouds.

An upper level low that was west of Baja California was producing westerly winds that were blowing toward the top of Tropical Storm Norbert.  Those winds were causing moderate vertical wind shear.  The moderate vertical wind shear was causing the asymmetrical distribution of thunderstorms.

The strongest winds were blowing in the northeastern part of Tropical Storm Norbert.  Winds to tropical storm force extended out 60 miles (95 km) in the northeastern quadrant of Norbert’s circulation.  The winds in the other parts of Tropical Storm Norbert were blowing at less than tropical storm force.

Tropical Storm Norbert will move through an environment that will be somewhat favorable for intensification during the next 24 hours.  Norbert will move over water where the Sea Surface Temperatures are near 29°C.  However, the upper level low west of Baja California will continue to cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification.  Tropical Storm Norbert is likely to intensify slowly because of the moderate vertical wind shear.

Tropical Storm Norbert will move around the southern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Norbert toward the west during the next 24 hours,  On its anticipated track, Tropical Storm Norbert will move farther away from Baja California.

Elsewhere, Tropical Storm Lowell continued to spin far to the northwest of Hawaii.

At 5:00 a.m. EDT on Thursday the center of Tropical Storm Lowell was located at latitude 29.2°N and longitude 166.2°W which put the center about 655 miles (1050 km) northwest of Lihue, Hawaii.  Lowell was moving toward the west at 13 m.p.h. (21 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 993 mb.

Lowell Weakens to a Tropical Storm

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Former Hurricane Lowell weakened to a tropical storm as it moved away from Kauai on Tuesday evening.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Lowell was located at latitude 26.2°N and longitude 161.1°W which put the center about 310 miles (500 km) north-northwest of Lihue, Hawaii.  Lowell was moving toward the north at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 978 mb.

Former Hurricane Lowell weakened to a tropical storm on Tuesday evening.  A large upper level trough that was south of the Aleutian Islands was producing strong southerly winds that were blowing toward the top of Lowell’s circulation.  Those winds were causing strong vertical wind shear.

The strong vertical wind shear was affecting the structure of Tropical Storm Lowell.  Thunderstorms were still occurring in bands in the northern half of Lowell’s circulation.  Bands in the southern half of Tropical Storm Lowell consisted primarily of showers and lower clouds.  Storms near the center of Lowell generated upper level divergence that pumped mass away to the north of the tropical storm.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Tuesday.

The strong vertical wind shear also caused the distribution of wind speeds in Tropical Storm Lowell to become more asymmetrical.  Winds to tropical storm force extended out 250 miles (400 km) in the northern side of Lowell’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) in the southern side of Tropical Storm Lowell.

Tropical Storm Lowell will move through an environment that will be unfavorable for intensification during the next 24 hours.  Lowell will move over water where the Sea Surface Temperatures are near 26°C.  However, the upper level trough that is south of the Aleutian Islands will continue to cause strong vertical wind shear.  Tropical Storm Lowell will continue to weaken on Wednesday because of the strong vertical wind shear.

Tropical Storm Lowell will move south the southern side of a high pressure system that is over the North Pacific Ocean.  The high pressure system will steer Lowell toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Lowell will move farther away from Hawaii.

Karina and Lowell Churn Westward

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Hurricane Karina and Tropical Storm Lowell were churning westward over the North Pacific Ocean on Monday evening.

At 11:00 p.m. EDT on Monday the center of Hurricane Karina was located at latitude 17.8°N and longitude 126.6°W which put the center about 1135 miles (1830 km) west-southwest of the southern tip of Baja California.  Karina was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 950 mb.

Hurricane Karina maintained its intensity on Monday as it churned west over the Eastern North Pacific Ocean.  A circular eye with a diameter of 12 miles (19 km) was at the center of Karina’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Karina’s circulation.  Storms near the core of Karina generated upper level divergence that pumped large amounts of mass away from the hurricane. The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure was nearly constant on Monday.

The distribution of wind speeds in Hurricane Karina was fairly symmetrical.  Winds to hurricane force extended out 30 miles (50 km) from the center of Karina’s circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Hurricane Karina.

Hurricane Karina will move through an environment favorable for a strong hurricane during the next 24 hours.  Karina will move over water where the Sea Surface Temperatures are near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Karina is likely to maintain its intensity on Tuesday.

Hurricane Karina will move around the southern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Karina toward the west-northwest during the next 24 hours.  On its anticipated track, Hurricane Karina will continue to move farther away from Baja California.

Elsewhere, Tropical Storm Lowell intensified gradually on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Lowell was located at latitude 13.0°N and longitude 147.4°W which put the center about 690 miles (1110 km) southeast Hilo, Hawaii.  Lowell was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 993 mb.

Karina Rapidly Intensifies to a Major Hurricane

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Hurricane Karina rapidly intensified to a major hurricane on Sunday evening as it moved over the Eastern North Pacific Ocean southwest of Baja California.  At 8:00 p.m. EDT on Sunday the center of Hurricane Karina was located at latitude 17.2°N and longitude 123.4°W which put the center about 960 miles (1545 km) west-southwest of the southern tip of Baja California.  Karina was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 955 mb.

Hurricane Karina rapidly intensified to a major hurricane on Sunday evening.  The inner end of a rainband wrapped around the center of Karina’s circulation.  A circular eye with a diameter of 25 miles (40 km) formed at the center of Hurricane Karina.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Karina’s circulation.  Storms near the core of Karina generated strong upper level divergence that pumped large amounts of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The inner core of Hurricane Karina was very small.  Winds to hurricane force extended out 15 miles (25 km) from the center of Karina’s circulation.  Winds to tropical storm force extended out 205 miles (335 km) from the center of Hurricane Karina.

Hurricane Karina will move through an environment mostly favorable for intensification during the next 24 hours.  Karina will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, there is a mass of drier air just to the west and north of Hurricane Karina.  The drier air will inhibit intensification of Karina, but the drier air probably will not be enough to prevent intensification.  Hurricane Karina is likely to intensify during the next 24 hours.  Karina could continue to intensify rapidly during the next few hours, if the drier air does not get pulled into its circulation.

Hurricane Karina will move around the southern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Karina toward the west-northwest during the next 24 hours.  On its anticipated track, Hurricane Karina will move farther away from Baja California.

Elsewhere, Tropical Storm Lowell moved over the Central Pacific Ocean.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Lowell was located at latitude 13.3°N and longitude 141.8°W which put the center about 985 miles (1585 km) east-southeast Hilo, Hawaii.  Lowell was moving toward the west at 13 m.p.h. (21 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.

Karina Strengthens to a Hurricane

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Former Tropical Storm Karina strengthened to a hurricane as it moved over the Eastern North Pacific Ocean southwest of Baja California on Saturday night.  At 5:00 a.m. EDT on Sunday the center of Hurricane Karina was located at latitude 17.3°N and longitude 121.1°W which put the center about 820 miles (1325 km) west-southwest of the southern tip of Baja California.  Karina was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 980 mb.

Former Tropical Storm Karina strengthened to a hurricane on Saturday night.  The inner end of a rainband wrapped around the western and southern sides of the center of Karina’s circulation.  An eye appeared to be forming at the center of Hurricane Karina.

The distribution of thunderstorms in Hurricane Karina was asymmetrical.  Thunderstorms were mostly occurring in bands in the southern half of Karina’s circulation.  Bands in the northern half of Hurricane Karina consisted primarily of showers and lower clouds.  Storms near the center of Karina generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the northeastern part of Hurricane Karina.  Winds to hurricane force extended out 25 miles (40 km) in the northeastern quadrant of Karina’s circulation.  Winds to tropical storm force extended out 230 miles (370 km) from the center of Hurricane Karina.

Hurricane Karina will move through an environment mostly favorable for intensification during the next 24 hours.  Karina will move over water where the Sea Surface Temperatures are near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, there is a mass of drier air just to the west and north of Hurricane Karina.  The drier air will inhibit intensification of Karina, but the drier air probably will not be enough to prevent intensification.  Hurricane Karina is likely to intensify during the next 24 hours.  Karina could intensify rapidly at times, if the drier air does not get pulled into its circulation.  Karina strengthen to a major hurricane by Monday morning.

Hurricane Karina will move around the southern part of a high pressure system that is over the Eastern North Pacific Ocean.  The high pressure system will steer Karina toward the west-northwest during the next 24 hours.  On its anticipated track, Hurricane Karina will move farther away from Baja California.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Lowell was moving west toward the Central Pacific.  At 5:00 a.m. EDT on Sunday the center of Tropical Storm Lowell was located at latitude 13.2°N and longitude 139.1°W which put the center about 1150 miles (1850 km) east-southeast Hilo, Hawaii.  Lowell was moving toward the west at 10 m.p.h. (16 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.

Tropical Storms Karina and Lowell Form over Eastern North Pacific

Tropical Storms Karina and Lowell formed over the Eastern North Pacific Ocean on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Karina was located at latitude 11.1°N and longitude 111.9°W which put the center about 825 miles (1330 km) south of the southern tip of Baja California.  Karina was moving toward the west-northwest at 13 m.p.h. (21 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 1001 mb.

Two low pressure systems over the Eastern North Pacific Ocean strengthened on Thursday afternoon and the U.S. National Hurricane Center designated the systems as Tropical Storm Karina and Tropical Storm Lowell.

Thunderstorms were developing in bands in the southern and eastern parts of Tropical Storm Karina.  Bands in the northwestern part of Karina’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Karina generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The strongest winds were occurring in the northern part of Tropical Storm Karina.  Winds to tropical storm force extended out 205 miles (335 km) in the northern side of Karina’s circulation.  The winds in the southern side of Tropical Storm Karina were blowing at less than tropical storm force.

Tropical Storm Karina will move through an environment favorable for intensification during the next 24 hours.  Karina will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Karina will intensify during the next 24 hours.  Karina could strengthen to a hurricane by Saturday morning.

Tropical Storm Karina will move around the southwestern part of a high pressure system that is centered over the Southwest U.S.  The high pressure system will steer Karina toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Karina will move far to the southwest of Baja California.

At 5:00 p.m. EDT on Thursday the center of Tropical Storm Lowell was located at latitude 11.3°N and longitude 133.8°W which put the center about 1765 miles (2840 km) west-southwest of the southern tip of Baja California.  Lowell was moving toward the east-northeast 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 1006 mb.

Tropical Storm Lowell is forecast to move west toward the Central North Pacific Ocean and to strengthen to a hurricane during the weekend.

Tropical Storms Karina and Lowell and the Fujiwhara Effect

I am sometimes asked what happens when two tropical cyclones get close to each other.  The answer depends on the relative size and intensity of the two systems and how close they come to each other.  The Fujiwhara Effect is the name given to the tracks taken by the two vorticies.  If the two tropical cyclones are of nearly equal size and intensity, then they tend to move cyclonically around a center of rotation that is roughly half way between them.  If one cyclone is much bigger and stronger, then the center of rotation is shifted toward the bigger and stronger cyclone.

Tropical Storm Lowell has a large circulation and a maximum sustained wind speed of around 50 m.p.h.  Tropical Storm Karina is located about 700 miles to the west-southwest of Lowell.  Karina has a much smaller circulation and it also has a maximum sustained wind speed of 50 m.p.h.  Some of the models are forecasting that the two tropical storms will rotate around a point closer to Lowell than to Karina (i.e. the Fujiwara Effect).  This would result in Lowell moving general west-northwest and pass to the north of Karina.  The larger circulation of Lowell could also pull Karina back toward the east-northeast as Karina passes south of Lowell.  It is also possible that the circulation of Lowell could be so big that it captures Karina and Karina eventually gets absorbed by Lowell.