Strong, broad area of high pressure north of the Hawaiian Islands will begin to meander northeastward, easing the local pressure gradient resulting in trades decreasing to a more moderate to breezy pattern, persisting through the rest of the week. Some models showing unsettled weather returning to the islands by early next week, but prevailing trades with periods of windward and mauka showers is looking like the more likely outcome through early next week.
Strong, broad area of high pressure remains just north of the Hawaiian Islands while a trough of low pressure extending well west has created a local pressure gradient strong enough to continue moderate to locally breezy trades. Latest model guidance portrays the area of high pressure to slowly meander eastward toward CONUS while the trough of low pressure remains idle west of the islands. While this will lessen the local pressure gradient, trades will prevail through at least the end of the week.
Latest observations from mid-level water vapor imagery depict much of the state remains under mostly cloudy conditions. Precipitation as a whole as simmered down for most islands, as indicated by the most recent one-hour rainfall summary, with the only exception being windward Big Island. Of course, this checks out with a more typical trade wind pattern focusing shower activity to windward and mauka areas and may very well trend through the next several days.
Model guidance continues to show discrepancies with the next period of unsettled weather for the Hawaiian Islands. A low is being illustrated just west of the state and eventually gets absorbed by an even larger system to the northwest early next week. Both the GFS and the ECMWF depict deeper moisture being drawn northward associated with the aforementioned system -- except retaining it west of the islands. Models begin to disagree shortly thereafter as the GFS shows the low developing northwest of the islands by the end of the forecast period, which may bring in heavier rain to the western islands. Conversely, the ECMWF shows a much weaker low developing even further north and keeping the moisture band west of the islands. Further detail will be required to see which situation becomes fruitful. For now, to account for the uncertainty, and for the sake of forecast continuity, have opted to continue advertising prevailing trades through the forecast period.
Breezy trades expected to gradually decrease over the next couple of days. Windward and mauka SHRA with possible MVFR conds. Otherwise VFR should prevail.
AIRMET Sierra remains in effect for mtn obsc for Oahu and the Big Island. Conds should improve mid morning.
AIRMET Tango remains in effect for mod turb below 070 for leeward sides of the islands. This will gradually improve as wind speeds continue to ease.
Nearshore buoys continue to show a slow decline in the seas along east facing shores, so the High Surf Advisory has been cancelled with the morning package. Rough elevated surf will continue for east facing shores. The Small Craft Advisory has been extended through Friday night for a combination of winds and seas.
Strong high pressure far north of the state will continue to produce rough marine conditions across the state through next week as another strong high builds far north of the state Friday into the weekend. ASCAT passes overnight continued to show SCA level winds across most of the coastal waters, and there remain pockets of seas at 10 feet. Winds are expected to increase again over the weekend, so expect the SCA to remain in place through the weekend.
As mentioned above, surf along east facing shores has dropped just below HSA levels, but will remain rough and elevated for the foreseeable future. Trades are expected to restrengthen over the weekend into early next week, which will produce another round of advisory level surf and possibly warning level surf along east facing shores of Oahu and Kauai.
Small to medium northwest swells will continue through the weekend with smaller surf expected during the first half of next week. Currently we have a small northwest swell that filled in yesterday that will be followed by slightly larger northwest swells today and Friday. Small along south facing shores will continue to remain small with some background windswell for select exposures.
Thunderstorms remain a possibility in the offshore waters to the southwest and west of the Hawaiian coastal waters, due to an upper level trough in the area. While this upper level feature is expected to weaken over the next couple of days, a new developing mid to upper level trough moving in from the northwest will maintain the possibility for thunderstorms through the weekend.
Winter Weather Advisory until 6 AM HST early this morning for Big Island Summits.
Small Craft Advisory until 6 AM HST Saturday for all Hawaiian waters-
