Issued: Dec 09, 2013 2:30 AM HST
Based on data through 2:00 am Dec 09 2013 HST
A nearly stationary upper trough remains near the Big Island with a trough axis stretched from a relatively weak upper low near 29°N 148°W across the Big Island to 13°N 157°W. Widely separated, isolated thunderstorms can be observed along the trough. A second weak upper level trough depicted in earlier satellite data between Kauai and Oahu is no longer recognizable. An impulse of energy from an upper jet far NW of the islands is feeding occasional thunderstorms over the Kauai N offshore waters where cloud tops are reaching 40 thousand feet.
The influence of the upper trough near the Big Island keeping a rather unstable airmass across the islands. Further to the NW of the island chain, a front stretched SW from 30°N 162°W through 25°N 170°W. A fairly narrow, 50 to 60 mile wide associated cloud band ahead of the front is moving ESE at 15 to 20 miles an hour. The band consists of bkn to ovc low clouds with a few thunderstorms along it. A low pressure system associated with the front was centered near 38°N 161°W and is quickly departing N. Layered clouds associated with the aforementioned low cover much of the area between 25°N to 30°N and 156°W to 180. A large cluster of thunderstorms can be observed centered around 28.9°N 158.4°W, or about 480 miles N of Oahu. Mid and upper clouds also cover much of the are between 10°N to 25°N and 144°W to 155°W, including the E half of the Big Island.
At 2 am HST, Kauai remains cloudy to mostly cloudy with bkn to ovc low clouds and passing bands of showers from the S. On the Big Island, mainly sct low clouds prevail, except for the windward coastline and most of the SE portions of Mauna Loa where bkn to ovc high clouds continue to stream S to N. On Maui county, sct low clouds prevail over the county with narrow bands of upper clouds passing from NW to SE. On Oahu, mainly sct low clouds prevail except over the Waianae range and portions of the leeward coastline where locally bkn low clouds with a few showers linger.
S of the islands, a cluster of active thunderstorms can be observed centered around 10.9°N 153.7°W, or about 580 miles SE of the Big Island. Cloud tops in this cluster were reaching 42 thousand feet.