Issued: Apr 23, 2014 7:30 PM HST
Based on data through 7:00 pm Apr 23 2014 HST
A brisk trade wind flow prevails over the Hawaiian islands this evening, with varying amounts of low clouds tracking toward the islands, and stacking up along windward coasts and slopes. The strong trades are briefly pushing these scattered to broken low clouds over leeward areas of the smaller islands, while the leeward coast and slopes of the Big Island and adjacent near shore waters, from Keahole Point to South Point, are under broken to overcast low clouds. Low clouds and showers near the islands are moving toward the west-southwest at 25 to 30 mph.
On Kauai, the leeward, or western, half of the island is under nearly clear skies as of bulletin time, with clear skies over Niihau and adjacent waters. The windward side of the island, and the north shore, are under scattered to broken cumulus /cu/ and stratocumulus /sc/. Most of Oahu is currently under scattered to broken showery cu, except for the southwest corner of the island, where few cu are seen. Few to scattered low clouds prevail over the islands of Maui county, and adjacent waters, while a cloudier evening is underway over the windward side of the Big Island, where broken to overcast cu and sc are over the slopes, while the adjacent windward waters currently only contain scattered cu.
Randomly distributed patches of low clouds prevail upstream of the islands for several hundred miles, and lack significant organization. A 500 to 700 mile long, 75 to 100 mile wide, east to west oriented band of broken cu lies over waters to the north and northeast of Kauai, but appears to be moving on a trajectory that would keep it north of the islands. The portion of the tropical central north Pacific west and northwest of the main Hawaiian islands is under few to scattered cu, with dry conditions prevailing from 10°N to 30°N between 160°W and the date line. Low clouds are in greater concentration to the east and northeast of the islands, with scattered to locally broken low clouds seen from 10°N to 30°N E of 160°W.
Patches of scattered to broken high-level cirrus clouds are noted about 200 to 1200 miles northeast of the islands, and water vapor imagery shows these clouds are associated with a northeast to southwest oriented trough aloft, and a dissipating embedded low aloft, that is about 300 miles northeast of the islands. This broad trough has an axis that passes north of Kauai, along a line from 30°N 154°W to 24°N 165°W to 19°N 180°, with a westerly flow aloft prevailing over the islands.