Hawaii Island Weather Outlook for March 22nd, 2021
Unstable weather conditions continue to settle over the Island of Hawaii, bringing with it moderate to heavy showers over many parts of Hawaii Island. Conditions are likely expected to continue through Tuesday (March 23rd).
Published by: HIRSC - Weather Team
The trade winds will weaken and veer southeast tonight due to an approaching cold front. Nighttime land breezes and daytime sea breezes will replace the trades after midnight for many areas. A pre-frontal convergence band will set up across the smaller islands Tuesday night and bring widespread showers that will continue through Thursday over these areas. Trade winds will push the boundary westward to Kauai on Friday with drier weather by the weekend.
A 1035 MB surface high is centered around 1500 miles northeast of Hawaii driving moderate trade winds this afternoon. A cold front is located about 500 miles northwest of Kauai moving toward the islands at about 25 mph. Winds are expected to weaken and veer southeasterly tonight before becoming light and variable on Tuesday. Nighttime land breezes will set in for some areas around the state after midnight with sea breezes expected for all islands Tuesday. The southeast flow is also moving clouds and showers over the Big Island this afternoon. An upper-level trough east of the Big Island will slowly weaken tonight. Some instability will remain in the vicinity of the Big Island into Tuesday. Given the moisture around the Big Island at this time, a slight chance of thunderstorms is forecast for Tuesday afternoon. The smaller islands will likely get afternoon cloud build-ups and a few interior showers as it is more stable. As the front moves closer, a pre-frontal convergent band will set up over the smaller islands beginning Tuesday night. The rain coverage could cover anywhere from Kauai to Maui, but looks like the central to the western portion of the state will be the main focus. The upper-level support for this front is expected to stay too far north for any significant rainfall/flash flooding, but with the southerly flow and the band moving very slowly, light to moderate rain could linger over the same islands until Thursday. Remnant moisture will hang around Kauai until Friday as the trade winds build in from the east and push the boundary back to the west. Expect drier trade wind weather for the weekend.