The National Weather Service in Honolulu is forecasting a significant change in weather for the Hawaiian Islands as a strong winter low pressure system approaches. According to their latest update by the National Weather Service, residents can expect the transition from cool and pleasant conditions to more severe weather starting today, as winds shift out of the south-southeast. The main threats from tomorrow through Friday include heavy rainfall that could lead to flash flooding, damaging winds, and the potential for strong to severe thunderstorms.
For today, while the morning may start dry and cool with dewpoints in the 50s, the atmosphere will soon become more volatile. "The low-level flow will quickly respond and increase, while veering out of the south to southeast through the day, drawing warm and moist air northward," the report by the National Weather Service describes. Increases in dewpoints are expected, reaching the mid to upper 60s by the end of the day, ramping up the chances of isolated to scattered showers, particularly on south through east facing slopes.
In terms of aviation, a shift is anticipated with moderate easterly winds veering southeast as the low pressure nears. This will manifest mainly as MVFR conditions and a few showers over the windward and mauka locations. However, as the front closes in, the forecast suggests a deterioration to MVFR/IFR conditions, along with high gusty winds, and thunderstorms becoming more probable.
The marine outlook is equally concerning, with the NWS warning of gale-force winds, thunderstorms, and periods of heavy rain. Mariners are advised to prepare for a deteriorating environment. "A Gale Watch remains in effect for the waters around Kauai from tonight through Thursday," the National Weather Service notes. On top of that, a new north-northwest swell is expected to peak this morning; however, a larger one is forecasted for tomorrow into Friday, potentially reaching advisory levels for north facing shores.
While critical fire weather conditions are not projected through the forecast period, the islands are on alert for other hazards. A High Wind Watch and Winter Storm Watch have been issued, encompassing all Hawaiian Islands and specifically noting the Big Island Summits with a warning starting from noon today. Behind the front, the weather is predicted to improve markedly over the weekend, bringing some respite after these turbulent conditions pass.
