Issued: Apr 17, 2014 2:00 AM HST
Based on data through 2:00 am Apr 17 2014 HST
Low ceilings, some with accompanying showers, have been at least intermittent over windward and mauka sections on the individual isles this early morning. This has especially been the case over Oahu, east Maui, and the Big Island as of bulletin time. Leeward areas are predominantly clear to partly cloudy. Low cloud movement is from the east-northeast near 25 mph across the aloha state.
A small cluster of broken showery low clouds exists over and immediately east of the Big Island and is heading west-southwest on the prevailing trade flow. Skies are otherwise clear to scattered over the adjacent coastal waters.
Since last evening, there have been subtle changes in the atmosphere above 25 thousand feet, according to the most recent water vapor images. The axis of a trough is roughly along a line from 23°N 153°W to just over Maui county to 15°N 166°W. The southern portion of the system has been drifting west and appears to be consolidating there, while the northern segment has been nearly stationary and weakening. Upper winds east of the trough axis are from the south and southwest, and high clouds, debris from convection that has been occurring far south and southwest of Hawaii, have been riding these winds toward the north and northeast. Some cirrus elements are occasionally getting within 20 miles east of the Big Island.
A front far west of the state has crossed the date line near 30°N as of bulletin time. The feature is still only peripherally affecting Midway atoll, with mainly high cloud ceilings and winds from the southwest near 10 mph as of this writing.
Showers and thunderstorms have increased in number and intensity over the past seven hours along the intertropical convergence zone far south of Hawaii. Most of the convection has been firing from 03°N to 08°N east of 165°W. More activity is occurring south of 03°N west of 174°W.