Issued: Sep 30, 2014 2:30 AM HST
Based on data through 2:00 am Sep 30 2014 HST
Water vapor images showed an area of low pressure in the middle atmosphere over the main Hawaiian islands. Thunderstorms forming under this feature were organized into three main groups, a line of very strong cells within 75 miles of the line from 26°N 158°W to 22°N 155°W, a single strong cell within 75 miles of the point 17°N 162°W, and a cluster of relatively small cells within 90 miles of the point 21°N 162°W. Small possible thunderstorms also were present offshore to the south-southwest of Oahu. Layered high to middle debris clouds from this and earlier convection partly to mostly obscured lower features within 150 miles of the line from 27°N 153°W to 23°N 150°W.
To the northwest, towering cumuli and possible thunderstorms associated with a front were located within 75 miles of the curve from 28°N 165°W to 26°N 169°W to 26°N 177°W. Fragments of cloud layers at various heights shearing off of the main frontal cloud band partly to mostly obscured lower features within 90 miles of the line from 30°N 161°W to 22°N 166°W.
To the southeast through southwest, moderate thunderstorm activity continued in the ITCZ from 12°N to 04°N. Layered middle to high debris clouds from this and earlier convection mostly obscured lower features from 14°N to the equator. Thinner high cloud layers following a jet stream out of the ITCZ also mostly to partly obscured lower features within 60 miles of the curve from 16°N 140°W to 19°N 149°W to 16°N 160°W to 16°N 164°W to 12°N 170°W.
Otherwise, cloud cover across Hawaiian waters consisted mainly of moderately packed marine stratocumuli and stratus layers east of about 155°W. Individual small cumuli also were present throughout. These clouds generally moved toward the west at around 15 miles an hour, and rose to heights of 8000 to 10000 feet, though taller cumuli approached 15000 feet.
Across the main Hawaiian islands, cloud cover consisted mostly of marine stratocumuli and stratus fragments moving ashore over Maui county, and layered middle to high debris clouds flowing over Kauai county from thunderstorms offshore to the west. Towering cumuli also developed over southeast Maui. Layered debris clouds from afternoon cumulus buildups on Monday largely had dissipated or moved offshore.
Radar data from near the islands showed a large area of heavy rain well to the northeast of the state, scattered heavy showers over southeast Maui, scattered heavy showers offshore to the west of the Big Island, and scattered heavy showers offshore to the south through west of Oahu. Elsewhere, radar data showed isolated showers at most.