Breezy trades continue through the period with a brief uptick in windward and mauka showers anticipated Friday night.
Subtropical jet established around the southern periphery of an upper low north of Kauai is spreading high clouds across area skies, particularly over the Big Island. High cloud coverage increases over the remainder of the state during the next few days as the aforementioned low and attendant upper jet drift westward. Otherwise these features remain inconsequential through the near term.
At the surface, a typical breezy trade wind pattern prevails beneath an inversion anchored at approx 7kft. Pockets of showers are evident on local visible imagery, and these will be directed windward and mauka during the next 24 hours by easterly trades. Upstream, the remnants of a cold front embedded in the trades continues advancing toward the islands. This band generally presents as showery low clouds up to 9kft in depth except where deep convection is triggered along its convergent lead edge. During the next 24 hours, convergence will weaken owing to a lack of upper level support and the deepest moisture will likely be compromised by the hostile (dry, stable) local environment. As such, suspect the local thunderstorm threat will be quite low. Instead, expect a healthy coverage of trade wind showers Friday night with a few pockets of deeper convection potentially bringing a brief period or two of heavier rainfall. Typical breezy trade wind pattern returns thereafter.
Locally breezy trades will continue for the next several days. Limited clouds and showers will favor windward and mauka areas, with an uptick in activity expected Friday night. Expect mainly VFR across the state, with periods of MVFR possible in passing showers.
AIRMET Tango remains in effect for moderate low level turbulence over and downwind of island terrain. This AIRMET will likely be needed for the next several days as breezy trades persist.
AIRMET Sierra for tempo mountain obscuration remains in effect over windward Oahu, with conditions slowly improving this evening and overnight.
High pressure to the north-northeast of the area will remain in place for the next several days, keeping moderate to locally strong trade winds across the islands. The daytime ASCAT pass did not show winds at Small Craft Advisory (SCA) thresholds for the Maui Windward waters, so the SCA has been scaled back to our typical windy areas around Maui County and the Big Island. Trades should gradually ease Sunday into early next week as the high weakens to our north.
Surf along south facing shores should see an increase this weekend as a small to moderate, long-period, south southwest swell gradually fills in late Friday into Saturday and peaks late Saturday into Sunday. Surf heights should rise back up to near or above the September average over the weekend then gradually decline next week.
Surf along north facing shores saw a small increase today due to a short-period north swell. This small bump is expected to peak on Friday out of the north to north-northeast direction, followed by a short period north northwest swell this weekend. Moderate to locally strong trades near and upstream of the area will lead to choppy conditions along east facing shores over the next several days. A slight increase of windswell is expected over the weekend due to a fetch of strong winds as seen on ASCAT today near 30N140W.
Small Craft Advisory until 6 PM HST Friday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
