The warnings were prompted by an unusually strong low pressure system and cold front moving through the islands. The strong pressure gradient around the low produced the high winds near the surface, while a strong upper level trough maintained the strong winds at the higher elevations.
|North Pacific surface analysis for 8:00 a.m. HST January 2.|
Last night at 6:00 p.m. HST winds at Mauna Kea on the Big Island were west sustained at 79 mph gusting to 139 mph with the temperature at 28°F. The highest wind gust recorded early this morning was 155 mph near the summit of Mauna Kea at the Canada-France-Hawaii Telescope weather station
|Timer trace of the wind speed and direction near the summit of Mauna Kea.|
|CoCoRaHS observations for Hawaii the morning of January 3.|
Colder air in the wake of this system spread across the island chain today. Island residents were able to observe cold air cumulus today, a common occurrence here in the continental U.S. in the spring and fall but very rare in the tropical Pacific. These clouds develop as much colder air at middle and upper levels creates in a vertical temperature profile that favors the vertical formation of cumulus. As the surface warms cold weather cumulus quickly form and often fill in to result in overcast conditions.
|Overcast skies from cold weather cumulus on the north shore of Oahu at 10:30 a.m. HST January 3.|
A dry trade wind pattern is forecast to redevelop across the islands early next week.