Tropical Storm Pena moved south of Hawaii on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Storm Pena was located at latitude 11.4°N and longitude 157.6°W which put the center about 540 miles (870 km) south-southwest of South Point, Hawaii.  Pena was moving toward the west at 8 m.p.h. (15 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 1002 mb.

Tropical Storm Pena weakened on Sunday as it moved south of Hawaii.

Thunderstorms were still occurring near the center of Tropical Storm Pena.  Thunderstorms were also present in bands in the northern and eastern periphery of Pena’s circulation.  Bands in the western and southern parts of Tropical Storm Pena consisted primarily of showers and lower clouds.  Storms near the center of Pena generated less upper level divergence that pumped less mass away from 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 Sunday.

The strongest winds were occurring in the northeastern part of Tropical Storm Pena.  Winds to tropical storm force extended out 45 miles (75 km) in the northeastern quadrant of Pena’s circulation.  The winds in the other parts of Tropical Storm Pena were blowing at less than tropical storm force.

Tropical Storm Pena will move through an environment that will be somewhat favorable for intensification during the next 24 hours.  Pena will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the eastern part of an upper level trough that is southwest of Hawaii.  The upper level trough will produce southwesterly winds that will blow toward the top of Pena’s circulation.  Those upper level winds will cause moderate vertical wind shear.  The moderate vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification.  Tropical Storm Pena could intensify a little during the next 24 hours, if the upper level winds do not get any stronger.

Tropical Storm Pena will move around the southern side of a high pressure system that is over the Central North Pacific Ocean.  The high pressure system will steer Pena toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Pena will remain far to the south of Hawaii.

Tropical Storm Pena strengthened as it moved south of Hawaii on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Storm Pena was located at latitude 11.4°N and longitude 154.5°W which put the center about 530 miles (855 km) south of South Point, Hawaii.  Pena was moving toward the west 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 993 mb.

Tropical Storm Pena strengthened on Saturday.  Thunderstorms were occurring near the center of Pena’s circulation.  Thunderstorms were also occurring in bands in the eastern side of Tropical Storm Pena.  Bands in the western side of Pena’s circulation consisted primarily of showers and lower clouds.

Storms near the center of Pena generated upper level divergence that pumped mass away to the northeast of the tropical storm.  The removal of mass caused the surface pressure to decrease.

The circulation around Tropical Storm Pena was small.  The strongest winds were occurring in the northern side of Pena’s circulation.  Winds to tropical storm force extended out 35 miles (55 km) in the northern half of Tropical Storm Pena.  The winds in the southern half of Pena’s circulation were blowing at less than tropical storm force.

Tropical Storm Pena will move through an environment that will be somewhat favorable for intensification during the next 24 hours.  Pena will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level trough that is southwest of Hawaii.  The upper level trough will produce southwesterly winds that will blow toward the top of Pena’s circulation.  Those upper level winds will cause moderate vertical wind shear.  Tropical Storm Pena could intensify slowly during the next 24 hours, if the upper level winds do not get any stronger.

Tropical Storm Pena will move around the southern side of a high pressure system that is over the Central North Pacific Ocean.  The high pressure system will steer Pena toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Pena will remain far to the south of Hawaii.

Tropical Storm Pena formed southeast of Hawaii on Friday afternoon.  At 4:00 p.m. EST on Friday the center of Tropical Storm Pena was located at latitude 11.3°N and longitude 150.1°W which put the center about 650 miles (1045 km) southeast of South Point, Hawaii.  Pena was moving toward the west at 12 m.p.h. (19 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 1002 mb.

A low pressure system over the Central North Pacific Ocean southeast of Hawaii strengthened on Friday afternoon and the U.S. National Hurricane Center designated the system as Tropical Storm Pena.

The inner end of a rainband wrapped around the eastern side of the center of Tropical Storm Pena.  Other bands of showers and thunderstorms were revolving around the center of Pena’s circulation.  Storms near the center of Pena 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 northeastern part of Tropical Storm Pena.  Winds to tropical storm force extended out 45 miles (75 km) in the northeastern quadrant of Tropical Storm Pena.  The winds in the other parts of Tropical Storm Pena were blowing at less than tropical storm force.

Tropical Storm Pena will move through an environment favorable for intensification during the next 24 hours.  Pena 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 Pena is very likely to intensify during the next 24 hours.  Pena could move into a region where there is more vertical wind shear on Sunday.

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