SynopsisA ridge will maintain gentle winds over the islands through Saturday afternoon, with mainly fair weather over most areas. Southeast winds will carry some showers over the Big Island. A front will reach Kauai Saturday evening, bringing widespread showers and gusty north winds as it advances to the Big Island by Sunday morning. Cool, dry weather will spread over the islands behind the front. A new ridge northwest of the islands will bring a return of gentle trade winds by Monday night.
DiscussionQuite a bit of low clouds continue to affect Oahu Molokai and Lanai this evening, bringing some showers to those islands. Big island has cleared quite a bit as the daytime convection collapses, while Kauai has mostly fair weather since it is on the northwest fringe of the area of low clouds. Expect these clouds to linger in the island vicinity through rest of the evening into early Saturday morning, keeping Oahu Molokai and Lanai somewhat cloudy. Mainly fair weather will prevail over the Big Island, while Kauai may eventually see some of these low clouds. Interestingly, latest wind profile from Kauai radar indicated light northerly wind flow at the lowest level, hinting a weak surface high just west of the island. Winds will become light enough to allow land breezes to develop. But then the aforementioned low clouds in the island vicinity may hint the process a little.
Winds will remain light across the area through early part of Saturday as the front northwest advances closer to the islands. Sea breezes will develop under the light winds, as well clouds and light showers over leeward and interior areas under daytime heating.
The pending cold front is still expected to reach Kauai Saturday evening, bringing more clouds and showers with strong gusty north winds behind it. Winds may become strong enough to reach advisory level for areas across the islands susceptible to the northerly wind flow. The front will move down the island chain, reaching the Big Island by Sunday, while weakening. Cool dry air will spread over the state behind the front. Nighttime low temperatures will drop into the lower 60s and the 50s early next week. It will feel even cooler with the low dew point expected. A surface ridge will build eastward behind the front, bringing northeast trade winds to the area late Sunday into Monday.
The ridge of high pressure is expected to sag south to near the state through early part of next week, keeping winds light. Forecast models indicate airmass will remain somewhat dry and stable. There is disagreement between the long range models on what the next front from the north will do. Latest GFS has this feature a little stronger, and will advance through the northern islands by the middle of next week bringing some showers while ECMWF has this feature staying north of the area, with little impact on the island weather.
AviationVfr will prevail over most of the island chain tonight and into Saturday morning. However, showery conditions over the southeast Big Island will bring tempo MVFR there. Isolated MVFR is possible elsewhere around the isles as daytime clouds collapse and cloudiness to the south of the state moves north.
No airmets are currently in effect.
MarineStrong north winds behind the front as well as the arrival of a large north-northwest swell will bring small craft advisory level wind and sea conditions to most coastal waters late Saturday into Sunday. A small craft advisory is posted for most of the coastal waters beginning Saturday afternoon. The northerly direction of the winds will lead to strong winds in areas where the winds are usually light, such as the Kona coast.
The pending large north-northwest swell will bring near advisory levels surf for north and west facing shores beginning late Saturday. This swell will peak Sunday into Monday, then slowly subside. Another large northwest swell is expected by the middle of next week, bringing possibly warning levels surf for north and west facing shores of most islands.
HFO Watches/Warnings/Advisories.small craft advisory beginning 200 pm HST Saturday for coastal waters of all islands except Big Island windward, southeast and leeward waters.