Lingering instability over the islands continues to produce showers and isolated thunderstorms over the smaller islands. Light southerly winds today will result in some afternoon sea breezes that could produce additional showers and thunderstorms over interior portions of the islands. Trade winds are expected to slowly make a return tonight, and strengthen into the first part of the new week.
The main change with the morning forecast package was to add thunderstorms over the smaller islands and surrounding waters for today and tonight. Lingering instability from the stationary front and trough to the north of the main Hawaiian islands will be eroded by upper level high pressure to the southeast of the islands moving over the islands tonight. Light winds over the islands today will lead to afternoon sea breezes that will likely help contribute to afternoon convection over the smaller islands.
The threat for widespread flooding remains low, but with saturated grounds over the islands, particularly on Kauai and Oahu, additional showers could prompt additional flood advisories at times.
As the surface boundary is eroded, high pressure far north of the islands will sink southward bringing trade winds back to the region as early as late tonight. Trade winds will then strengthen to moderate to locally breezy levels by Monday or Tuesday. The trades will carry in residual moisture from the surface boundary to the windward and mauka areas. The GFS and ECMWF are in good agreement with an mid-level high pressure ridge remaining over the islands through the end of the week.
An unstable atmosphere remains in place over the islands with light southerly flow. Clouds and showers continue to move over the smaller islands, bringing occasional MVFR conditions, and isolated IFR conditions. Thunderstorms will also continue to be a possibility that could produce gusty conditions and briefly heavy rain. The Big Island is expected to have primarily VFR conditions, but the occasional shower moving overhead could bring brief MVFR conditions.
Wind may be light enough to day for afternoon sea breezes that could help to initiate some afternoon convection over the islands. Trades are expected to return late today.
AIRMET Sierra for mountain obscuration is in effect for Lanai, Kahoolawe and Maui. This may need to be expanded to additional areas at times.
A lingering unstable airmass will lead to another round of scattered showers and isolated thunderstorms today over the western coastal waters with light and variable flow. Gentle to locally moderate southeasterly winds will prevail across the eastern waters with less shower activity. By late this weekend, easterly trade winds will gradually strengthen with the potential for SCA conditions over the windier waters and channels around Maui County and the Big Island. Expect trades to become even stronger early to mid next week as surface high pressure builds to the north.
Two overlapping small to moderate, medium period, northerly swells (350 deg) and (010 deg) will dominate through the remainder of this weekend and bring elevated surf to north facing beaches. However, surf should stay just shy of High Surf Advisory criteria and combined seas will remain below Small Craft Advisory criteria. Late Sunday through mid next week, north swell energy fades which should allow surf to drop to below seasonal averages.
Surf along east facing shores will remain small through tonight given the lack of trade winds upstream of the islands, but areas exposed to the north swell will see an uptick. As trade winds gradually strengthen late Sunday through early next week, east facing shores could become rough and choppy. Surf along south facing shores will remain flat to tiny through the weekend into early next week.
None.
