Tropical Storm Norbert churned west toward the Central North Pacific Ocean on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Norbert was located at latitude 17.9°N and longitude 130.5°W which put the center about 1610 miles (2595 km) east of Hilo, Hawaii. Norbert 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.
Tropical Storm Norbert weakened on Saturday. A large upper level low that was northeast of Hawaii produced southwesterly winds that blew toward the top of Norbert’s circulation. Those winds caused moderate vertical wind shear. In addition, Norbert moved into a mass of drier air that was east of Hawaii. The moderate vertical wind shear and drier air caused Tropical Storm Norbert to weaken on Saturday.
The moderate vertical wind shear and drier air also caused many of the thunderstorms in Tropical Storm Norbert to weaken. Thunderstorms were still occurring in bands in the northern side of Norbert’s circulation. Bands in the southern half of Tropical Storm Norbert consisted primarily of showers and lower clouds. Since there were fewer thunderstorms near the center of Norbert’s circulation, those storms generated less upper level divergence. The removal of less mass caused the surface pressure to increase on Saturday.
The asymmetrical distribution of thunderstorms in Tropical Storm Norbert also affected the distribution of wind speeds. Winds to tropical storm force extended out 105 miles (165 km) in the northern half of Norbert’s circulation. Winds to tropical storm force only extended out 35 miles (55 km) in the southern side of Tropical Storm Norbert.
Tropical Storm Norbert will move through an environment that will be mostly unfavorable for intensification during the next 24 hours. Norbert will move over water where the Sea Surface Temperatures are near 26°C. The upper level low that is northeast of Hawaii will continue to produce moderate vertical wind shear. Norbert will also continue to move through the mass of drier air that is east of Hawaii. Tropical Storm Norbert is unlikely to intensify on Sunday because of the moderate vertical wind shear and the drier air.
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 toward Hawaii on Sunday.
