Breezy trade winds will persist for the next several days. Trades winds will increase in strength tonight into Saturday due to a tropical disturbance passing well to the south of the area and a strong high building in from the northwest. Enhanced trade wind showers are also anticipated for windward areas tonight into the weekend as tropical moisture surges in from the south. Isolated thunderstorms will also be possible for Big Island tonight and Friday. A drier airmass and more stable conditions will return Sunday into next week with limited showers focusing mainly along windward and mauka areas.
Latest surface analysis shows a ridge of high pressure north of the state is driving breezy trades across the island chain today and a pair of troughs southeast of the Big Island. The Wind Advisory for the Kohala District of Big Island has been cancelled as winds have eased below advisory levels.
Radar imagery show numerous light to moderate showers moving east to west across the state. Rainfall totals for the past 12 hours show most windward areas received between 0.3 to over 1.0 inch, including some central areas of Oahu. Satellite imagery shows a broad area of thinning low level clouds just upstream of the state indicating shower coverage should trend down during the day today.
Starting tonight, another area of enhanced low level clouds associated with a trough southeast of Big Island will draw deep tropical moisture and precipitable water values near 2.50 inches from the south later this afternoon. This will increase the chance of showers for windward Big Island before spreading to Maui County tonight into Friday. Isolated chance of thunderstorms capable of producing heavy downpours also cannot be ruled out for Big Island tonight through Friday as this area of moisture erodes the inversion heights, allowing for some terrain induced convection to occur. These showers are expected to be brief and move quickly within the breezy trade wind flow so not anticipating issuing a Flood Watch at this time. ASCAT imagery overnight showed a large fetch of strong northeast winds ahead of this trough that will reach the eastern half of state tonight, strengthening winds to advisory levels due to terrain enhancements near peaks and points, as well as along and downslope of ridges. Thus a Wind Advisory for select areas of Maui County and the Big Island may need to be issued later this afternoon if this area remains intact.
NHC continues to monitor the high likelihood of a developing tropical cyclone withing the next day or so well southeast of the state. This area will follow close behind the first trough, Friday into Saturday as a ridge of high pressure builds in from the northwest, tightening the pressure gradient across the state. This could translate to trade winds strengthening across the state, maintaining or expanding advisory level winds for select areas across the island chain.
After the system passes west of the state Saturday into Sunday, a much drier airmass and lower inversion heights will filter in from the east into next week. Winds will ease to more typical breezy levels. The drier airmass and lower inversion heights will also limit shower coverage to mainly windward and mauka areas.
Breezy trades expected for next few days. Low cigs and SHRA will continue over windward and mauka locations with some spillover into leeward areas at times. MVFR conds in SHRA, otherwise VFR prevails.
AIRMET Sierra is in effect for mtn obsc for windward portions of all island except Lanai. Conds should improve in the mid morning hours.
AIRMET Tango remains in effect for mod turb lee of terrain and should remain in effect for next few days.
Fresh to strong trade winds with periods of near gales will remain in place throughout the week as a broad area of high pressure remains in place north of the state. Small Craft Advisory (SCA) is in effect for all Hawaiian Waters and the SCA conditions will likely persist across the state through the weekend due to a combination of winds and seas. Additionally this weekend, a tropical cyclone could pass far south of the state. According to National Hurricane Center, there is a high chance of formation during the next 48 hours. Latest satellite imagery is starting to show better organization during the past 6 hours.
Surf along north and west-facing shores will quickly build this morning as a new long-period north-northwest swell arrives. Buoy readings at buoy 51001 has ranged from 7 to 9 ft and 16 to 19 seconds over the past several hours. Long-period energy is starting to arrive at the Waimea buoy this morning and we should see surf quickly rising throughout the morning hours across north and west facing shores. High Surf Advisory is in effect for most north and west facing shores of the smaller islands through tonight. This swell is expected to peak during the day today then fade over the next few days. Surf will likely be at borderline High Surf Advisory thresholds on Friday as the north-northwest swell declines. A wide fetch of gales seen on the ASCAT pass overnight near 40N180W, should send reinforcing medium period energy out of the north-northwest late Saturday into Sunday. Surf could approach advisory thresholds during its peak early Sunday morning. Another large northwest to north-northwest swell is possible towards the middle of next week.
A compact fetch of gales passing east of New Zealand last week Friday should produce some waves slightly above average around Friday into Saturday along south facing shores. Surf along east- facing shores will stay elevated and choppy through much of the week due to the strong trades. Select northeast exposures should see long-period energy from the large north-northwest swell today into tonight.
High Surf Advisory until 6 AM HST Friday for Kauai North-Kauai Southwest-Maui Central Valley North-Maui Windward West-Molokai North-Molokai West-Molokai Windward-Niihau-Oahu North Shore- Waianae Coast-Windward Haleakala.
Small Craft Advisory until 6 AM HST Saturday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.
