Breezy trades will gradually ease today becoming moderate to locally breezy Tuesday. Clouds and showers will be limited to windward and mauka areas with some spilling over to leeward areas. Breezy to locally windy trades will redevelop Wednesday through Thursday as a new strong surface high settles north of the state. A slight uptick in windward showers can be expected during the second half of the week as a band of moisture moves from north to south across the state. Moderate to locally breezy trades will return over the weekend.
Latest satellite imagery shows a pocket of low level clouds and showers just east of Oahu moving northwest towards Kauai early this morning and becoming more diffused. Radar shows scattered light showers focusing mainly along windward areas with some showers spilling over to leeward areas of the smaller islands. Overnight rainfall totals range from 0.20 to 0.40 for the wetter windward areas. The pressure gradient generated from a ridge of high pressure to the north and Tropical Storm Pena passing far southwest of the state will gradually relax today as the ridge weakens and Pena continues to track far southwest of the state. Thus expect trades to ease to more moderate to breezy levels tonight and Tuesday. Showers will trend down during the day with a slight increase tonight due to diurnal trends.
A strong surface high will sink just north of the state Wednesday into Thursday, strengthening trades back to breezy to locally windy levels. A dry and stable airmass will continue to support low inversion heights that could help accelerate gusty downslope winds near advisory levels. Will continue to monitor all available guidance and observations to determine if a Wind Advisory will be needed. A band of moisture embedded within the trade wind flow will track south over the state as early as Wednesday night through Thursday bringing an uptick in showers to exposed windward areas. The high will gradually weaken toward the end of the week into the weekend allowing trades to ease back to more typical moderate to locally breezy speeds while pockets of moisture focuses showers along windward and mauka areas.
Moderate to locally breezy trade winds will continue through the day today with a drier airmass in place. Isolated showers along windward areas may produce brief periods of MVFR ceilings and visibilities.
AIRMET Tango remains in effect for moderate turbulence below 8000 feet within the lee of higher terrain. This AIRMET will likely continue through the next several days as locally breezy trade winds persist.
Fresh to strong trade winds will gradually decrease through Tuesday as the subtropical ridge north of the state shows a slight weakening trend. Tropical Storm Pena continues to drift westward, passing several hundred miles south of the Hawaiian Islands. Trade winds will strengthen once again on Wednesday as the ridge builds in north of the island chain. A surface trough will move into the region from the north on Thursday, spreading unsettled clouds and showers across the coastal waters.
The Small Craft Advisory through this afternoon includes most Hawaiian coastal waters and this advisory was partially extended through Tuesday afternoon for the windier waters and channels near Maui and the Big Island.
A medium period swell out of the north-northwest (325 to 350 degree) will hold today as another small to moderate swell fills in later tonight, keeping elevated surf along north and west facing shores through Tuesday. A much larger northwest to north- northwest swell was generated by a gale force low developing east of Kamchatka. This large north-northwest swell may bring warning level surf heights to exposed north and west facing shores building in through the day on Wednesday, peaking Wednesday night, decreasing to advisory levels on Thursday, and then falling below advisory levels by Friday.
A small south swell will keep tiny surf in the forecast along south facing shores today before declining through the remainder of the week.
Rough surf along east-facing shores will hold at or above seasonal average today. Expect slight decreasing trends as trade winds ease up on Tuesday and Wednesday.
Small Craft Advisory until 6 PM HST this evening 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 PM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
