textproduct: Honolulu

SYNOPSIS

Typical summertime trade wind weather is expected throughout the week with some scattered showers focused near windward and mauka areas and mostly dry conditions over leeward areas. Trade winds will strengthen and become breezy to locally strong Friday into the weekend.

DISCUSSION

A weak trough to our west is making the trade winds slightly south of due east this afternoon over the western end of the state as seen on the daytime ASCAT pass. Otherwise we are seeing fairly typical summertime trade wind weather this afternoon with some light showers across parts of the state. Trade winds will continue to remain moderate to locally breezy and mainly out of the east direction rather than our typical east- northeast direction through Thursday.

As the trough to the west weakens and dissipates, a ridge of high pressure will strengthen to our north and we should see the return of breezy to locally strong east-northeast trade winds Friday into the weekend. Leeward areas will remain mostly dry with a few light showers possible during the morning and overnight periods. Kona slopes of the Big Island will continue to see afternoon clouds and showers each afternoon due to the sea breezes with showers and clouds gradually clearing during the night as land breezes develop.

In the upper levels of the atmosphere, we do have a strong jet overhead which will continue to bring a stream of high cirrus clouds at times throughout the week. Currently the high cirrus clouds remains over the eastern end of the state around Big Island. The high cirrus clouds could produce some unique colors in the sky during the sunrises and sunsets.

AVIATION

Moderate to locally breezy trades will continue across the island chain through this evening, then strengthen slightly tomorrow. Clouds and showers will tend to favor windward and mauka areas as pockets of moisture roll in on the trades, particularly during the overnight to early morning hours. Outside of any brief showers, VFR conditions will generally prevail through tomorrow.

No AIRMETs are currently in effect this afternoon. Overnight, AIRMET Sierra for mountain obscuration may be needed for windward areas if shower coverage expands and persists.

MARINE

High pressure remains anchored northeast of the islands through the week re-centering to north and strengthening this weekend. As a result, fresh to locally strong trades will become strong on a more widespread basis during the weekend into early next week. The Small Craft Advisory for the typical windier waters of Maui County and the Big Island has been extended through Thursday.

Fading SSW swell declines through Wednesday leaving tiny background energy in its wake. A small, moderate period S swell then brings a small bump by late this weekend. Pulses of small, short period energy of the N quadrant will keep north shores from going flat. Trades maintain short period chop and low amplitude fresh swell along E shores through the forecast period.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.