Hawaiian Islands Satellite Interpretation Message
Fri, 24 Sep 2010 00:30:00 -0500
Based on data through 0500 UTC September 24 2010.
The presence of a weak surface ridge about 390 miles north of Lihue continued to maintain relatively light trade winds across the Hawaiian island chain early this evening. This ridge continued to shift slowly southward toward the islands, so wind speeds continued to diminish. This was resulting in the development of local land breezes across some parts of the state at dusk this evening.
The relatively weak low-level trade wind flow was transporting scattered 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 general motion of the low clouds across the windward Hawaiian coastal waters was toward the west at about 15 mph. The highest tops of the low clouds over the ocean surrounding the Hawaiian islands were estimated to be about 5 thousand feet.
As of 700 pm HST Thursday, scattered to broken low clouds were over parts of Kauai, especially across the center of the island. Broken low clouds were along the Koolau and Waianae mountain ranges, as well as the windward shores of Oahu. Scattered to locally broken low clouds were over parts of Molokai. Small patches of low clouds were across portions of Lanai. On Maui, broken low clouds were above the lower slopes of mount Haleakala, the western mountains and the south central valley. Broken to overcast low clouds were across most of the Kona, Kau and south Kohala districts on the Big Island. Scattered low clouds were affecting parts of the lower elevations of the windward Big Island.
According to loops of water vapor imagery and satellite derived upper level winds, an upper tropospheric ridge was just west of Kauai this evening. As result, the upper level winds were 35 to 50 mph from the northwest across the state. Significant subsidence aloft was also evident in the water vapor imagery across parts of the island chain, especially near the Big Island. 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 was centered about 475 miles south of Honolulu. The trough, which has been moving slowly westward, extended from near 17°N 158°W to 11°N 159.5°W. The showers and isolated moderate thunderstorms were within 120 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.
Another weak trough extended from near 15.5°N 168°W to 08.5°N 170.5°W. This trough was also moving slowly westward. Disorganized showers and isolated moderate thunderstorms were within 300 miles east, and within 80 miles west of this trough. The highest tops of the thunderstorms in the vicinity of this weak trough were estimated to be about 45 thousand feet.
Elsewhere in the deep tropics far south of the Hawaiian islands, the intertropical convergence zone, or ITCZ, extended from near 09°N 140°W to 11°N 156°W, and from 10°N 173°W to 09.5°N 180°W. Scattered moderate thunderstorms were within 140 miles south of the ITCZ. The highest tops of the cumulonimbus clouds associated with the ITCZ were estimated to be about 49 thousand feet.
HOUSTON
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