SATELLITE DISCUSSIONBased on data through 1800 UTC May 25 2016.
A sharp mid to upper level trough is dropping over the main Hawaiian islands from the northwest. The axis of this feature runs from 30°N 159°W across Kauai to 17°N 161°W and is traveling toward to east-southeast at 15 mph. The upper trough is triggering small clusters of thunderstorms along a weak surface trough 125 to 300 miles north and northwest of Kauai, with an area of rather strong thunderstorms rising as high as 40000 ft about 250 miles north- northwest of Kauai.
Over the islands, an easterly low level trade wind flow veers out of the east-southeast across the western half of the island chain. A field of broken cumulus clouds with tops around 12000 ft and precipitable water values of around 1.4 inches is producing broken to overcast low clouds along windward slopes of the Big Island, Maui, and Molokai, with the exception of the Hamakua coast. This band of moisture lifts north of Maui and Molokai, where it is being enhanced by the advancing upper level trough. A few thunderstorm cells are forming within the northern extend of this field about 110 miles north of Molokai. Another area of moisture pooled west of Maui and the Big Island is producing extensive cloud cover over leeward Big Island this morning, with cloud tops remaining below 20000 ft.
The veering trade wind flow continues to keep a lesser amount of low level moisture near Oahu and Kauai this morning. Scattered to broken low clouds are banked on windward terrain, while leeward skies are mostly clear at this time.
Elsewhere, a portion of the ITCZ is producing thunderstorms from 12°N to 08°N west of 171°W. A narrow band of broken high clouds is streaming from this area and passing south of the Big Island. To the northwest, a weak trough just west of the date line is generating broken low clouds over Midway and kure atolls. Broken high clouds are also passing over this area.