Breezy trade winds driven by high pressure to the north will weaken to moderate levels by Wednesday becoming land and sea breezes this weekend. Lingering windward clouds and showers tonight trending drier Wednesday. A possible front near the west end of the state early next week.
Visible satellite shows clouds and showers associated with an old frontal band anchored along windward Maui and Big Island this afternoon, and to Molokai, Oahu and Kauai to a lesser degree. Expecting this low cloud cover to linger tonight with conditions becoming sunnier through the day Wednesday. Occasional high clouds will continue to track over the islands from a system west of the state that is not expected to impact the islands at least within the next 5 days. Breezy trade winds driven by high pressure to the north will weaken by Wednesday as the ridge builds in. While the short term trend will be drier and more stable, any clouds and showers running in the trade winds will focus windward and mauka through Friday.
The system will organize to a cold front and begin approaching the state late in the week. Winds will veer southeasterly across the state this weekend as it nears Kauai. Localized sea breezes will bring leeward clouds and showers during the afternoons and clearing at night. Long range model solutions slow and stall the front near or over Kauai around Monday or Tuesday. Model differences emerge at this point, and less forecast confidence persists on impacts and timing of the front.
Breezy trade winds today will become a bit lighter tomorrow. Enhanced clouds and showers associated with an old front can be seen on satellite imagery today moving swiftly across windward and mountain areas. Showers could linger through some of tonight as well, as there still remains a little moisture upstream of the trade wind flow. Showers and clouds should then substantially decrease tomorrow as drier air moves in, bringing VFR conditions to most locations.
AIRMET Sierra is in place for tempo mountain obscurations over all the islands except Oahu. This AIRMET should drop off later tonight as drier air moves in.
AIRMET Tango remains in effect for tempo moderate turbulence downwind of terrain on all islands below 8000 feet will likely continue through tonight.
Fresh to near gale easterly trade winds peaked today and will slowly decline tonight through Thursday. A robust 1037 mb surface high centered about 1500 nm north of Hawaii is driving the gusty trades, while a large area of low pressure centered roughly 1500 nm northwest of Kauai is causing the winds to be out of the east locally. The high will drift eastward and weaken tonight through Thursday, leading to a gradual decline in winds. A Small Craft Advisory (SCA) remains in place for a combination of winds and elevated seas for nearly all coastal waters and is scaled back to the typically windy waters around Big Island and Maui for Wednesday and Wednesday night. The SCA may need to be extended for another day or two as trades slowly ease. The low will move to the east Friday into the weekend, pushing a surface ridge near the islands and causing winds to further decline and eventually shift out of the southeast and south.
The current small north swell will continue to gradually decline into Wednesday. A moderate, medium period north-northeast (010-030 degrees) swell will arrive Wednesday and peak Christmas Day into Friday. Surf along north facing shores could approach the High Surf Advisory level during the peak, with the largest swells favoring the eastern end of the island chain, and a Marine Weather Statement will likely be needed for harbor surges at Kahului and Hilo. During this time, a small pulse of west swell is expected as well. The north swell will decline over the weekend as a small northwest swell arrives. A large north-northwest swell may arrive early next week.
Gusty trade winds will maintain elevated and rough east shore surf near the High Surf Advisory level through tonight, especially on Kauai and Oahu, where seas of 8 to 10 feet at 9 seconds have been measured on the nearshore PacIOOS buoy. Short period trade wind swell, which also contributed to the need for the SCA through tonight, will decline sharply Wednesday, but wrapping northerly swell will affect exposed eastern shores late Wednesday through Friday. Surf along south facing shores will remain very small through the week.
Small Craft Advisory until 6 AM HST Wednesday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters- Kauai Channel-Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters.
Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
