Issued: Feb 15, 2012 2:30 PM HST
Based on data through 2:00 pm Feb 15 2012 HST
Water vapor imagery shows a broad upper level trough over northwest sections of the area. A shortwave embedded within the larger trough is located near 30°N 170°W, or about 450 miles east northeast of Midway atoll. This trough is moving to the east at 70 mph. A cold front and band of layered clouds is associated with this trough. The back edge of the frontal cloud band extends from 30°N 162°W to 22°N 178°W. This band is up to 300 miles wide near 30°N, and decreases to less than 100 miles wide west of 170°W. Individual cloud elements are moving to the east northeast at 50 mph, while the overall cloud band is nearly stationary. An area of cirrus and cirrocumulus clouds is located east of the main frontal band. These high clouds are located generally north of 20°N west of 143°W.
South of the upper trough, water vapor imagery also shows an upper level ridge across the central Pacific, extending southwest to northeast across the main Hawaiian islands. South of the ridge, an upper level low is located near 08°N 154°W, or about 800 miles south of Hilo. Scattered to broken cirrocumulus clouds are located east of the low, generally from 07°N to 12°N east of 151°W. These clouds are moving to the east northeast at 60 mph.
Elsewhere across the central Pacific, areas of clouds are embedded in the low-level flow. The low clouds are greatest in coverage north of 23°N and east of 150°W, where they are composed primarily of stable stratocumulus and closed cell cumulus elements. South and west of this area, clouds transition to more showery open cell cumulus elements. Based on low-cloud motions, a surface ridge extends across northern sections of the area, roughly from 30°N 147°W to 25°N 160°W. South of 20°N, and south a line from 25°N 140°W to 20°N 160°W, cloud motions are to the west at up to 30 mph. North of this area, east to southeasterly winds south of the ridge turn southwesterly north of the ridge.
Across the main Hawaiian islands, cirrus clouds mentioned above cover most of the smaller islands, but are thin enough for low cloud features to be apparent. Broken low clouds cover the interior and leeward sections of Kauai. On Oahu, broken low clouds cover the slopes of the Koolau range, with broken to overcast low clouds across the Waianae range. Broken to overcast low clouds cover eastern Molokai east of kamalo, and interior sections of the rest of Molokai. Broken to overcast low clouds cover the interior and leeward sections of Lanai, and interior sections of the west Maui mountains. Broken to overcast low clouds cover the lower slopes of Haleakala below 6000 ft, and are thickest across windward slopes from nahiku to Hana to kaupo. These clouds extend offshore across the Alenuihaha channel.
On the Big Island, broken low clouds cover the slopes of the Kohala range, and lower slopes of Hamakua district below 9000 ft. Broken to overcast low clouds cover south Hilo and Puna districts, and portions of north Hilo district below 6000 ft. These clouds extend 20 miles offshore to the northeast and east. Broken to overcast clouds cover a portion of Kau district below 6000 ft from wood valley westward. These clouds also extend 40 miles offshore to the southeast. Broken to overcast clouds cover north and south Kona district below 10000 ft, and also south Kohala district south of Waikaloa.
