Issued: Apr 17, 2014 7:00 PM HST
High clouds streaking from the south and southwest have been moving over the isles and adjacent waters from Molokai to the Big Island this early evening. Most of the cloudiness is debris from convection that has been occurring in the deep tropics.
Below the cirrus clouds, low ceilings are concentrated over windward and mauka sections on the individual isles. Some of the broken cloudiness has been making its way over leeward areas of the smaller islands and west Maui as well. Broken to overcast low clouds have also been evident over the west-facing slopes of Haleakala in east Maui, and coastal and upslope parts of Kona and south Kohala on the Big Island. Low cloud movement is from the east to east-northeast at 15 to 20 mph across most of the aloha state, though speeds are 20 to 25 mph east clockwise through south of the Big Island as of bulletin time.
In the adjacent coastal waters, low clouds, a mix of stable and showery elements, are predominantly scattered, with small patches of broken low clouds randomly distributed over the area. On the other hand, a north-northeast to south-southwest oriented band of broken showery low clouds is approaching the Big Island from the east.
In the upper air above 25 thousand feet, the axis of a north- northeast-to-south-southwest oriented trough is roughly along a line from 23°N 156°W to just west of Oahu to 13°N 167°W, and has been drifting west. The winds on the east side of the feature are from the south and southwest, and it's these winds that have been carrying the high clouds toward the north and northeast over the islands.
The leading edge of broken to overcast low clouds with a front is about 720 miles northwest of Kauai at the moment, and has been pushing east near 20 mph along 30°N. Low clouds to the west of the leading edge are overcast at the Midway atoll observation site, and winds are from the northeast near 10 mph.
Along the intertropical convergence zone far south of Hawaii, showers and thunderstorms have been firing from 03°N to 06°N east of 142°W, and south of 04°N west of 170°W.