Trades will continue through the next week, bringing mainly windward and mauka showers. An upper level low will form just to our northeast Tuesday and then slowly move away to the NNE. The main impact of this low will be a slight increase in shower coverage and strength from Tuesday through around Thursday. Trade winds will increase in speed from Tuesday through next weekend.
This afternoon, radar and satellite show clouds and showers focused on windward and mauka areas. The strongest showers were over the Kau District on the Big Island. Other more consistent showers were over windward Maui.
The upper level pattern north of the islands will carry a series of troughs west to east across the Pacific Ocean through the next week, but for the most part these will be too far north to bring a significant change to the weather at the surface here in Hawaii. The lone exception will be a small and relatively weak closed low that is expected to form just to the northeast of the state late Tuesday. This low will then slowly track ENE away from the state through next weekend. Overall, the region will remain under the influence of ridging aloft to our WNW (centered around 25 deg N).
This upper low will not be strong enough to prevent trades from continuing at the surface, but it will bring a little more instability aloft, and therefore we may see some stronger showers Tuesday through Friday. Showers will remain mainly windward and mauka, and more numerous at night for most areas. Afternoon Kona showers, along with showers over the peaks of the Big Island, will remain in the forecast as well. Finally, from the middle of next week into next weekend, trades will become a stronger.
Moderate to locally breezy trades through mid-week. Low cigs and SHRA possible over windward and mauka locations. MVFR conds possible but VFR should prevail.
No AIRMETs in effect.
Easterly trade winds have eased slightly compared to the past couple of days as a weak surface trough moves through the region from east to west. Guidance indicates trades will strengthen somewhat tonight and Monday, with borderline Small Craft Advisory-level winds possible in the typically windier waters surrounding Maui County and the Big Island. Winds look to strengthen more significantly by mid-week as strong high pressure rebuilds far north of the state, with increased confidence for advisory-level winds, potentially including additional coastal waters.
Surf along north-facing shores will begin to gradually ease tonight into the first half of the week as the offshore buoy 51001 (to the northwest) shows decreasing medium-period swell energy over the past several hours. An upward trend is expected during the second half of the week as swell generated by a broad low near the Aleutians reaches Hawaii. Looking farther ahead, a storm- force low developing east of Japan on Monday looks to direct a longer-period northwest swell toward the islands for Friday and Saturday, with surf heights potentially approaching advisory levels along exposed north and west facing shores.
Surf along south-facing shores will remain somewhat inconsistent as a southwest swell peaks this evening/tonight. This will be followed by a gradual downward trend on Monday. Another small south-southwest pulse may arrive next weekend from activity within our swell window east of New Zealand.
Surf along east facing shores will remain relatively small and choppy, though a brief strengthening of the trade winds tomorrow could lead to a small bump in surf.
None.
