Trade winds will taper off through Friday as a front approaches the islands from the northwest. The front will move north to south across the islands chain Saturday night through Monday bringing rainfall focusing on windward slopes. Strong trade winds will follow the front that will continue into next week.
Satellite imagery indicates the ridge axis anchored north- northeast of the state with little upper level troughing. Radar shows light showers across windward and mauka locations. With the ridge being the dominant feature expect stable, moderate trades to veer east-southeast today and gradually decline. Any showers that do form will be mainly focused over windward and mauka spots. With lighter winds expect a sea/ land pattern to develop with isolated showers possible across leeward and interior locations Friday into Saturday.
From Sunday through midweek, a cold front is expected to arrive and move down the island chain. While the models do have some timing variations have chosen to go middle of the road for this package. GFS is a bit faster compared to the ECMWF which has the front reaching the Big Island by Monday as opposed to the faster GFS reaching it by Sunday afternoon into the evening. Strong trade winds overrunning the front will bring mostly windward showers, but many of the showers will blow over to the leeward sides of the smaller islands. With little to no upper-level support, rainfall is expected to be light with isolated pockets of some heavier rain. Showers are expected to be moving causing any training possibility to be limited at best. This should limit the flood potential. Breezy trade winds will continue behind the front into next week as ~1040 mb high sets up far north of the state. Conditions will remain stable, with scattered low clouds and windward and mauka showers.
Moderate trades will gradually ease and veer east- southeast today. A few windward and mauka showers can be expected today before we slide into a sea/land breeze regime through Saturday. Low cigs and SHRA could create some MVFR conds, however VFR prevails.
No AIRMETs in effect.
A high pressure ridge north of the Hawaiian Islands will weaken today in response to a weak cold front approaching the islands from the northwest. Expect decreasing wind speeds trends into Saturday as this cold front moves into the Hawaii Region. Fresh to locally strong northeast winds expected behind the front as it sweeps from north to south through the islands from Saturday evening through Monday. Fresh to locally strong trade winds will likely continue through Tuesday, with slightly stronger trade winds expected from Wednesday onward.
The highest swell energy with the current north-northwest (340-350 degree) swell continues to pass just northeast of the Hawaiian Islands. Swell heights have underperformed as compared to recent forecast model guidance and north swell bias trends. Therefore the High Surf Advisory (HSA) for north and west facing shores was cancelled this morning, as surf heights will remain just below HSA thresholds. This swell has peaked and will gradually fade heading into Friday. In the longer range forecast, a deep low pressure system is expected to develop to our north and northeast from Friday into Saturday. This low will likely generate a large north- northeast (010-020 degree) swell late this weekend, easily exceeding HSA thresholds. Due to the swell angle, heavy surges will be possible along north facing harbors such as Kahului and Hilo on Sunday.
South facing shores will remain small throughout this week. A small long-period south-southwest (190-200 degree) swell will boost south shore surf heights from Friday into the weekend, along with a larger out of season south swell possible by early next week. Surf for east facing shores will remain on the small side until later this weekend when trade winds strengthen across the region.
Peak monthly tides combined with water levels that are running higher than predicted will lead to minor flooding along the shoreline and in low-lying coastal areas. The greatest chance for coastal flooding will occur during the daily peak high tide during the early morning hours, and along north facing shores exposed to the large north-northwest swell.
None.
