Last Updated on Thursday, 12 December 2013 11:50
Issued: Dec 12, 2013 7:30 PM HST
Since this afternoon high, cirrus, clouds, CI have increased over the main Hawaiian islands partly obscuring the view of lower level clouds on nighttime infrared imagery.
On our last visible imagery, through about 530 pm, there were broken low clouds over Niihau, part of a 20 mile wide line of showery low clouds centered from 30 miles north northwest through 90 miles south southeast of Niihau. Overcast low clouds covered the north half of Kauai with scattered low clouds over the south half. Showery broken low clouds covered most areas of Oahu and Maui county with isolated low clouds over the summit of Haleakala. On the Big Island there were broken to overcast low clouds over the lower slopes, scattered clouds along the coast from Hilo to Apua Point and from Keahole Point to Upolu Point and isolated low clouds over the interior above about 5500 feet of elevation. Ci covers the area immediately upstream to the east northeast of the main Hawaiian islands but beyond the CI stable broken low clouds, mainly stratocumulus, are moving toward the islands from the east northeast. Overcast CI covers the area from the Big Island to the Kauai channel with thin broken CI over Kauai county.
A 100 mile wide frontal cloud band containing showery broken to overcast low clouds is north of a line from 28°N 140°W to 27°N 150°W, about 550 miles northeast of Hilo, to 30°N 153°W. The band has been nearly stationary.
A much more active cloud band is northwest of a line from 30°N 155°W to 28°N 160°W to 350 miles northwest of Kauai to 20°N 170°W to 16°N 180°W. The part of the cloud band north of 20°N is 450 miles wide and contains broken to overcast layered clouds, mostly CI. These clouds obscure most lower level features but the tops of embedded cumulonimbus clouds, CB, can be seen, mainly in a 120 mile wide band centered from 27°N 163°W to 21°N 169°W. The CB tops extend over 45000 ft. The CB between 27°N and 21°N have become much more active over the past few hours while CB north of 27°N have weakened. The part of the cloud band south of 21°N is 120 miles wide, containing showery broken to overcast low clouds and scattered towering cumulus clouds.
Water vapor imagery, which show features mainly above 24000 ft, shows a high-amplitude pattern with a trough aloft extending from 30°N 170°W to 20°N 172°W to 10°N 180°W and a ridge aloft from 30°N15OW over the Big Island to 10°N 161°W. A jet stream runs from 14°N 170°W to 20°N 163°W over Kauai to 23°N 154°W to 10°N 142°W.