textproduct: Honolulu

SYNOPSIS

Light winds are expected today as a front draws closer and our surface pressure gradient weakens. This front is still forecast to reach Niihau and Kauai Wed night, then stall near Maui Thursday night. Brief moderate rain may accompany this first front. Another front will approach this weekend, and heavy rain is possible. Details will become clearer later in the week.

DISCUSSION

Little has changed since the previous forecast as the models have shown good run-to-run consistency concerning the timing and placement of the Wed/Thu front. It should move through Niihau and Kauai Wed night, continue on to near Maui Thu night, then retreat northwest as it dissipates Friday. A second front will move over the western end of the state Sunday into Sunday night, with much more uncertainty in how far southeast it will be able to progress. At this time, we have increased the chance of rain Sunday through Monday, but have not added in a chance of thunder. We may end up doing that at some point, but it's too early now to specify exact locations.

In between these fronts, winds will be fairly light, allowing for additional days of sea- and land-breezes. This will favor clouds in leeward and mauka areas. Immediately behind these fronts, surface winds will likely come out of the north at light to moderate speeds.

AVIATION

Most sites will see VFR today into tonight, with relatively light winds. Isolated showers will be driven largely by sea-breezes today and land-breezes tonight. Southerly winds are possible at HNL from late morning into the afternoon.

No airmets are in effect, and none are expected today. Turbulence aloft is expected to increase Wed several hundred miles to our NW and N.

MARINE

A ridge of high pressure north of Hawaii will erode from the west as a front approaches the state from the northwest. Gentle to moderate easterly winds will weaken to light to gentle speeds and veer south to southeast today then southwest by Wednesday as the front approaches. The front will move west to east across the state late Wednesday into Thursday, with moderate northerly winds briefly filling in behind the front before it dissipates over Maui County Thursday night. Light southerly winds will redevelop Friday into Saturday as another front approaches the state from the northwest.

The first of two long to medium period overlapping northwest (310-320 degree) swells will continue to fill in this morning, building surf heights along north and west facing shores to near average. Forerunners of the second, slightly bigger swell will arrive tonight and peak Wednesday. Surf heights along north and west facing shores could reach marginal High Surf Advisory (HSA) levels Wednesday and hold into Thursday before slowly subsiding into the weekend. A moderate, long period northwest swell (320 degree) may gradually fill in over the weekend keeping surf from going flat.

Small, choppy east shore surf will become minimal over the next few days as trades near and upstream become disrupted by approaching fronts. Expect minimal background surf for south facing shores, with only a minor south- southwest pulse expected Wednesday afternoon into Thursday, keeping south shore surf heights just above flat levels.

FIRE WEATHER

Conditions should 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 6,500 to 7,500 feet through today.

HFO WATCHES/WARNINGS/ADVISORIES

None.