Issued: Nov 26, 2014 2:30 AM HST
Based on data through 2:00 am Nov 26 2014 HST
The relatively tight pressure gradient south of a nearly west to east oriented surface ridge located more than 400 miles north of Honolulu has been producing gusty trade winds across most of the main Hawaiian islands early this morning. The low-level trade wind flow was carrying broken to locally overcast low clouds across most of the windward coastal waters. Additional broken low clouds were evident across the leeward Kauai waters and the waters immediately southeast of the Big Island. Radar reflectivity data showed scattered showers embedded within the low clouds near the windward Big Island.
The individual low cloud elements across the windward coastal waters were generally moving toward the south southwest at 10 to 20 mph. The highest tops of the low clouds in the vicinity of the main Hawaiian islands were estimated to be about 7 thousand feet.
As of 200 am HST Wednesday, broken to overcast low clouds covered the northeastern two-thirds of Kauai, with scattered low clouds were elsewhere on that island. Broken low clouds were along the Koolau mountains and windward shorelines of Oahu, as well as the northeastern tip of Molokai. Skies appeared to be mostly clear on Lanai. On Maui, scattered to broken low clouds were above parts of the north and northeast facing shorelines, the lower windward slopes of mount Haleakala and the western mountains. Broken to overcast low clouds were along most of the windward coastal sections of the Big Island.
According to loops of water vapor imagery, the flow high above the main Hawaiian islands was nearly zonal from the west to west northwest at 20 to 25 mph early this morning. However, the axis of a mid-tropospheric trough extended from near 30°N 151°W across Kauai to 18°N 162°W. This feature has been propagating eastward at about 30 mph during the past 6 hours.
To the east of the main Hawaiian island chain, the southeastern edge of an approximately 130 mile wide band of broken to overcast low clouds and showers associated with a surface front extended from near 28°N 140°W to 24°N 143°W through a point about 390 miles east of Hilo to 15°N 157°W. This southeastern edge has been moving slowly eastward at about 10 mph north of 24°N, while it remained nearly stationary elsewhere. Far northwest of the main Hawaiian islands, broken to overcast layered clouds and showers associated with another front were northwest of a line from 30°N 165°W to 28°N 175°W through a point about 55 miles southeast of Midway atoll to 25°N 180°E.
In the deep tropics far south of the Hawaiian islands, the intertropical convergence zone, or ITCZ, extended from near 08°N 140°W to 06°N 160°W to 06°N 170°W to 04.5°N 180°E. Scattered thunderstorms were within 220 miles of the ITCZ west of 160°W. Isolated thunderstorms were within 130 miles of the ITCZ east of 160°W. The highest tops of the cumulonimbus clouds along the ITCZ were estimated to be about 54 thousand feet.