Breezy trades will gradually weaken to moderate speeds by the latter half of the week. Periodic showers will filter in on the trade wind flow, mainly focusing over windward and mauka areas through midweek. By the weekend, the background flow may become light enough to support land and sea breeze development, and showers may increase in some leeward areas.
An area of showers extended from Kauai County and Oahu east into the open waters this morning, and light showers have been frequent visitors to those islands. Maui County and the Big Island have been mostly dry. This pattern should continue into the daylight hours, especially over Kauai County, as satellite shows additional clouds capable of producing showers headed that way. The trade wind inversion is expected to remain around 7000 feet today, resulting in fairly stable conditions and no heavy rain is forecast.
With high pressure at the surface off to our northeast, trade winds will continue today and for several more days. The pressure gradient will begin to weaken Wednesday night into Thursday, and remain weak through the weekend, leading to lower wind speeds. This in turn will allow for a hybrid pattern of weak trade winds combined with sea and land breezes. And sea breezes during the day usually lead to an increase in afternoon clouds and showers over leeward areas. The forecast was moved farther in this direction with this latest update. Otherwise, the long range forecast calls for a return to stronger trades early next week. There are no tropical systems within range of the islands, and none expected over the next seven days (at least). Finally, models remain consistent in showing a front approaching the state from the northwest this weekend, but the moist band associated with it is not expected to reach us.
Moderate to breezy trade winds are expected to continue through Monday before gradually weakening heading into midweek. Showers embedded within the tradewind flow are primarily impacting windward and mountain areas, with limited spillover into leeward areas. Brief MVFR conditions are expected within showers while VFR prevails elsewhere.
No AIRMETs for mountain obscuration are in effect this morning, but it is possible that with clouds and showers moving in, it could be issued for any of the islands.
AIRMET Tango is in effect for mechanical turbulence downwind of the mountains due to breezy trade winds, and this is expected to continue through at least Monday.
Surface high pressure will remain anchored far northeast of the islands through early this week. A Small Craft Advisory (SCA), remains in effect for the typical windy waters around Maui and the Big Island until 6 PM tonight. By midweek, a ridge north of the islands associated with the high will be weakened and depressed southward resulting in even weaker trades. As the ridge shifts further south, it will eventually end up near the Hawaiian Islands by Friday or Saturday, which will bring light and variable winds across the area towards the end of the week.
Small long-period south swell continue to fill in this morning. Energy from this swell is expected to peak later today into tomorrow and bump up surf to slightly higher than the June averages, but still below advisory criteria. This swell is expected to fade through midweek. A smaller pulse of south- southwest swell is due late Thursday and Friday, and a more significant south- southwest swell is on track to arrive next weekend, likely bringing advisory level surf by late Sunday along south facing shores.
The combination of a large south-southwest swell coinciding with the peak monthly tides will lead to significant wave runup across areas of the shore that typically remain dry during the afternoon high tide cycle from June 14th through June 16th. Coastal flooding is also expected across low-lying coastal roadways, docks, boat ramps and other coastal infrastructure.
Small background energy from the west-northwest is possible over the next several days from a former Typhoon in the West Pacific last week.
Rough surf along east-facing shores will remain around seasonal averages slowly declining through midweek as trades ease. Surf will drop well below seasonal levels along east facing shores by the end of the week.
Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
