textproduct: Honolulu

SYNOPSIS

Winds will lighten up as a cold front approaches from the northwest. Daytime sea breezes and nighttime land breezes expected Tuesday and Wednesday with the front arriving Wednesday night and dissipating around Maui County Thursday night. Cool north winds briefly follow, then swing around to the south as the next system approaches over the weekend.

DISCUSSION

A 1027 mb surface high is centered far northeast of the state driving moderate trade winds across the area. Mostly sunny skies prevail this afternoon with a few leeward cloud build ups in some of the more sheltered locations from the trade winds where localized sea breezes have set up. Expect a few windward showers overnight and Tuesday morning as winds taper off due to an approaching front from the northwest. Afternoon sea breezes will set up over all islands on Tuesday as the ridge backs off and Hawaii becomes more under the influence of the front. Land breezes will clear skies Tuesday night followed by a repeat for Wednesday.

The front will be a thin band of clouds and showers will weaken as it reaches Kauai Wednesday night, Oahu Thursday and then dissipate over Maui County Thursday night. Moderate to breezy cool northerly winds will blow in as the front passes through Maui County. The band will diminish and lift northward as high pressure builds in over the state.

Winds will lighten again as the next front approaches from the west Friday and Saturday. The latest long range model guidance shows large inconsistencies on when or if this frontal cloud band will bring another round of showers to the state beginning late Saturday night into early next week.

AVIATION

VFR conditions will prevail across most sites tonight into Tuesday, with some isolated showers at times in windward areas. Light winds will likely allow sea breezes to form late morning Tuesday, which would persist through sunset (05z).

AIRMET Tango is in effect from Maui to Big Island for upper level turb but this will decrease tonight.

MARINE

A weak surface ridge will remain north of the main Hawaii Islands this evening, producing gentle to moderate easterly winds. Winds will decrease and veer southeasterly on Tuesday, then southwesterly on Wednesday as a cold front approaches the region from the northwest. This front is expected to move across the western Hawaiian islands late Wednesday into Thursday, bringing moderate to fresh north to northwesterly winds in its wake. Then winds will become light and variable on Friday as the front dissipates over the central Hawaiian islands.

The current medium-period north-northwest (340-350 degree) swell will continue to slowly fade this evening, maintaining below average levels for this time of year. The first of two long to medium period overlapping northwest (310-320 degree) swell pulses started trickling in earlier this afternoon, and will gradually build surf along north and west facing shores into Tuesday. The following bigger pulse will arrive late Tuesday into Wednesday, further boosting surf heights and possibly reaching marginal High Surf Advisory (HSA) levels by Wednesday. Near-average surf heights will generally hold into Thursday and decline heading into the weekend.

Choppy east shore surf will remain small and decline for the next few days as trades ease. Expect minimal background surf for south facing shores, with only a minor south-southwest pulse expected Wednesday into Thursday, keeping south shore surf heights just above flat levels.

FIRE WEATHER

Conditions remain below critical fire thresholds through the week as winds remain light and RH elevated. Temperature inversion heights over Maui and the Big Island will range from 5,500 to 6,500 feet through Tuesday.

HFO WATCHES/WARNINGS/ADVISORIES

None.