A potential chance of heavy rain caused by Tropical Storm Moke prompted the U.S. National Weather Service to issue a Flood Watch for portions of the Big Island of Hawaii on Saturday. At 5:00 p.m. EDT on Saturday the center of Tropical Storm Moke was located at latitude 14.9°N and longitude 151.1°W which put the center about 425 miles (680 km) southeast of Hilo, Hawaii. Moke was moving toward the west-northwest 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 996 mb.
Flood Watches are in effect for the windward and southeastern parts of the Big Island of Hawaii.
Tropical Storm Moke strengthened a little on Saturday. Even though Moke was a little stronger, the distribution of thunderstorms was still asymmetrical. Thunderstorms were occurring in bands in the northern side of Moke’s circulation. Bands in the southern side of Tropical Storm Moke consisted primarily of showers and lower clouds.
An upper level trough that was just east of Hawaii was continuing to produce southwesterly winds that were blowing toward the top of Tropical Storm Moke. Those winds were causing moderate vertical wind shear. The vertical wind shear was causing the asymmetrical distribution of thunderstorms.
The distribution of wind speeds in Tropical Storm Moke was also asymmetrical. Winds to tropical storm force extended out 115 miles (185 km) in the northern side of Moke’s circulation. Winds to tropical storm force only extended out 45 miles (75 km) in the southern half of Tropical Storm Moke.
Tropical Storm Moke will move through an environment that will become unfavorable for intensification during the next 24 hours. Moke will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough just east of Hawaii will continue to cause moderate vertical wind shear. In addition, Tropical Storm Moke will move into a mass of drier air that is south of Hawaii. The vertical wind shear and the drier air are likely to cause Tropical Storm Moke to start to weaken on Sunday.
Tropical Storm Moke will move around the southern side of a high pressure system that is north of Hawaii. The high pressure system will steer Moke toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Storm Moke will start to pass south of Hawaii on Sunday.
Bands in the northern part of Tropical Storm Moke could bring gusty winds to the Big Island of Hawaii. The strongest winds will occur at higher elevations. Those same bands could also drop heavy rain over parts of the Big Island. Heavy rain would likely cause flash floods because the ground is still saturated from rain caused by Hurricane Lala.
Flood Watches are in effect for the windward and southeastern parts of the Big Island of Hawaii.
Elsewhere over the Central North Pacific Ocean, Hurricane Lala was weakening gradually as it moved far to the northwest of Hawaii. At 5:00 p.m. EDT on Saturday the center of Hurricane Lala was located at latitude 31.0°N and longitude 172.7°W which put the center about 380 miles (614 km) east-northeast of Kure Atoll. Lala was moving toward the northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 981 mb.
