Hawaii faces heavy weather as a cold front from the northwest brings rain and isolated thunderstorms. The front is expected to weaken near western waters and merge with a previous system. Niihau, Kauai, and Oahu could see more showers and thunderstorms mid to late this week, while high pressure may bring drier conditions heading into the holiday week.
Recently, Kauai and Niihau received several inches of rain, while Oahu’s mountains saw lighter but still significant rainfall. The National Weather Service said today will be similar to Monday, with occasional showers adding up to a tenth of an inch in northern areas. The front is expected to stall near Kauai in the afternoon and may linger into the evening.
The NWS says the front may stall at Kauai due to weak upper-level support. Western islands could see scattered showers or an isolated thunderstorm from southern moisture and midweek jet activity. With mid to high-level clouds covering most islands, surface cloud formation is unlikely. Forecasters noted that rain will come from upper-level forcing in a moisture-rich air mass, which could cause minor flooding midweek in low-lying areas of Oahu and Kauai.
Showers should taper off by Friday as winds shift easterly, with trade winds returning this weekend. An upper-level ridge will reinforce the pattern, bringing typical trade wind weather before Christmas. Early next week, a strong North Pacific high may bring gusty easterly winds from Monday through Wednesday.
A surface trough northwest of Kauai has led the NWS to issue an AIRMET Sierra for morning mountain obscurations across Oahu, Molokai, and Lanai, improving by afternoon. AIRMET Tango alerts for moderate turbulence between FL240 and FL340 are in effect over Kauai and Oahu due to subtropical jet activity.
Marine forecasts indicate winds weakening later this week, with trade winds possibly returning by Sunday. A subsiding north swell has eased the elevated surf that prompted the High Surf Advisory. Both the High Surf and Small Craft Advisories expired at 6 a.m. East shores should remain calm except for northwest swells, while South shores may be choppy from southerly winds.
