Hawaiian Islands Satellite Interpretation Message
Fri, 24 Sep 2010 07:30:00 -0500
Based on data through 1200 UTC September 24 2010.
The presence of a weak surface ridge about 325 miles north of Lihue continued to maintain relatively light trade winds across the Hawaiian island chain early this evening. This ridge was shifting slowly southward toward the islands, so wind speeds have continued to diminish overnight tonight. This has resulted in the development of local land breezes across some parts of the state.
The relatively weak low-level trade wind flow was transporting small patches of low clouds and a few showers across portions of the windward coastal waters. Plumes of scattered to locally broken low clouds and isolated showers also extended west southwest of some of the islands. The largest of these plumes was just west of the Big Island. The general motion of the low clouds across the windward Hawaiian coastal waters was westward at about 15 mph. The highest tops of the low clouds over the ocean surrounding the Hawaiian islands were estimated to be 8 to 9 thousand feet.
As of 200 am HST Friday, scattered to locally broken low clouds were along the windward shores of Kauai. Scattered low clouds were affecting the windward shoreline of Oahu, and the eastern tip of Molokai. Skies appeared to be mostly clear across Lanai. On Maui, scattered to locally broken low clouds were along the windward coast, the lower windward slopes of mount Haleakala and the western mountains. Scattered low clouds were above parts of the windward shoreline of the Big Island.
According to loops of water vapor imagery and satellite derived upper level winds, an upper tropospheric high was centered near 15.5°N 157.5°W, or about 400 miles south of Honolulu. As result of the clockwise circulation around this feature aloft, the upper level winds were 30 to 45 mph from the northwest across the aloha state. Significant subsidence aloft was also evident in the water vapor imagery across the island chain. These factors were contributing to the relatively stable atmospheric conditions that have been occurring across the state.
A disorganized area of showers and isolated thunderstorms associated with a north to south oriented surface trough centered about 570 miles south of Honolulu. The trough, which has been moving westward at about 10 mph, extended from near 17°N 159.5°W to 10°N 160.5°W. The showers and isolated moderate thunderstorms were within 80 miles on either side of the trough. The highest tops of the cumulonimbus clouds associated with this feature were estimated to be about 44 thousand feet.
Elsewhere in the deep tropics far south of the Hawaiian islands, there were two other surface troughs evident. One of these troughs extended from near 08.5°N 140°W to 11.5°N 156.5°W. Scattered moderate thunderstorms were within 200 miles south of this trough. The second trough extended from near 15°N 169°W to 08.5°N 175°W. Isolated moderate thunderstorms were within 420 miles east, and within 270 miles west of this trough. The highest tops of the thunderstorms associated with these troughs were estimated to be about 47 thousand feet.
HOUSTON
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