Issued: Apr 27, 2015 2:30 AM HST
A 180 to 240 mile wide band of overcast layered clouds lies west of a line from 40°N 137°W to 35°N 140°W to 26°N 149°W. This feature continues southwestward as a 180 mile wide band of broken to overcast low clouds west of a line from 26°N 149°W to 20°N 157°W to 16°N 164°W. The band of low clouds, marking a weakening frontal boundary, lies across the main Hawaiian islands from the Kauai channel to the Big Island. The cloud band is moving toward the east at 10 to 15 mph north of 30°N, but gradually becomes stationary just southwest of the Hawaiian islands.
Satellite loop shows that broad anticyclonic circulations govern low level flow on both sides of the frontal boundary. These circulations, actually subtropical highs, are centered near 35°N 130°W and 38°N 172°W. The frontal boundary divides two flow regimes across the islands, with southeasterlies across waters just east of the Big Island contrasting with strong northeasterlies across waters just northwest of Kauai.
All of the main Hawaiian islands except Kauai are covered by broken to overcast low clouds, with Oahu, Molokai, Lanai, Maui and the Big Island directly affected by the frontal cloud band. Northerly flow keeps a pall of broken stable low clouds across the northern half of Kauai.