Last Updated on Monday, 29 September 2014 23:50
Issued: Sep 30, 2014 8:30 AM HST
An area of low pressure in the middle and upper levels of the atmosphere continues to produce unstable conditions over and around the main Hawaiian islands. Based on water vapor data, the low was centered about 220 miles northeast of Hilo and was moving slowly northeastward. Two areas of thunderstorms are associated with the low. The larger area extended 50 miles on either side of a line from 27°N 159°W to 22°N 156°W and has been weakening over the past several hours. The closest thunderstorm to the island chain was 90 miles northeast of Oahu. A smaller area of isolated thunderstorms extended about 50 miles north of a line from 21°N 160°W to 21°N 164°W with its closest cell about 30 miles southwest of Hanapepe. This area was also weakening over time.
To the northwest of the main Hawaiian islands, a cold front cloud band was progressing slowly to the southeast. The band was 500 to 600 miles wide with its leading edge along a line from 30°N 160°W to 25°N 167°W, which is just northwest of French Frigate Shoals in the Papahanaumokuakea marine national monument. Thunderstorms within the band were within 150 miles of the leading edge. Outside of the thunderstorms, the rest of the frontal band consisted of broken to overcast layered clouds.
Over the state, initial visible sector images revealed scattered to broken low clouds over Kauai, and broken to overcast low clouds over the lower windward elevations of the Big Island. South Maui near wailea and Ulupalakua also had broken low clouds overhead. The rest of the state appeared to have just few to scattered low clouds. An east-west oriented 100 mile-wide band of broken high clouds associated with the above mentioned upper level low was sending occasional fragments of thin cirrus over the southern portion of the Big Island.
Far to the south, thunderstorm activity in the intertropical convergence zone, ITCZ, was mainly south of 10°N with the exception of a northward bulge up to 12°N 147°W.