textproduct: Honolulu

SYNOPSIS

A breezy to windy trade wind pattern will persist through at least Wednesday, then gradually wane through the rest of the week. Moisture embedded in the trades will allow showers to favor windward and mauka areas. An overall wetter pattern is possible this weekend as additional moisture is drawn over the island chain.

DISCUSSION

A stationary 1037 mb surface high is centered north northeast of Hawaii this morning. A stationary front is located 600 miles northwest of Kauai. 12Z soundings showed a subsidence driven inversion with by strong dry advection in the mid-levels supported by high dewpoint depressions. Winds continue to blow strong across the state at advisory levels (sustained speeds of 30-39 mph and/or gusts 50-57 mph) across portions of islands, especially over higher terrain, passes, and areas immediately south through west of mountains. A Wind Advisory goes through 6pm HST today for these portions of the state. By Thursday, winds will begin to decrease, but remain locally strong throughout the rest of the work week.

As far as precipitation is concerned, little change is expected over the next few days, with occasional showers and clouds embedded within the trades favoring windward and mauka areas over the next several days. Things begin to get a bit more interesting near the end of the week, as an overall pattern shift could ultimately lead to several days of wet and unstable trade this weekend into early next week.

Latest guidance remains in good agreement that southeast flow in the lower levels could expand moisture over the islands late this week, then stall it over the state for at least Saturday and Sunday. While it is still very early, this will be closely monitored for potential flooding that could develop in this scenario. As the previous discussion pointed out, however, forecast confidence will largely depend on the expected strength of trades, which will in turn modulate forward motion of showers. The latest guidance continues to indicate that the islands could reside somewhere along the gradient between stronger trades to the east and light southeast flow to the west (though where exactly this sets up could make a large difference in rainfall potential for the islands). Still too early for specifics as there remains a lot of room for error, but something to continue monitoring throughout the rest of the week.

AVIATION

Breezy to strong easterly trade winds are expected through the next few days as strong high pressure resides to the north and low pressure resides far to the west northwest. Winds will be gusty at as well. Mid level ridging will keep conditions stable, which could enhance the wind gusts, as well as keep showers from getting too heavy. Showers should effect mainly windward and mountain areas, and will likely be more widespread during the overnight hours. Conditions should stay mostly VFR with pockets of MVFR at night with any passing showers.

AIRMET Tango is in effect for tempo moderate turbulence below 7000 feet over leeward sides of the islands as a result of the gusty winds. This AIRMET will likely continue through tonight.

MARINE

Strong high pressure will remain far northeast of the state during the next couple of days, as a slow moving front approaches from the west. The front will stall out and weaken into a trough just a few hundred miles west of the islands this weekend, with a new high building in to the distant north. A Gale Warning remains in effect for the Pailolo and Alenuihaha Channels as well as Maalaea Bay through 6 PM this evening, with a Small Craft Advisory (SCA) in effect for all other waters. The SCA will likely need to be extended through at least Thursday for all waters once the Gale Warning is taken down. The trade winds and seas are then expected to gradually lower Friday through the weekend.

Surf will hold relatively steady along east facing shores during the next couple of days, and as a result the High Surf Advisory (HSA) has been extended through 6 PM Thursday. As the trade winds ease late in the week and over the weekend, surf along east facing shores will gradually lower below HSA thresholds.

Surf along north and west facing shores will remain well below seasonal levels through the weekend, and surf along south facing shores will remain very small.

Forerunners from a large, long-period north to north-northeast swell are forecast to arrive Sunday night, then rapidly build to advisory and potentially warning levels along north facing shores late Monday through Tuesday.

HFO WATCHES/WARNINGS/ADVISORIES

High Surf Advisory until 6 PM HST Thursday for east facing shores of Kauai, Oahu, Molokai, Maui, and the Big Island.

Wind Advisory until 6 PM HST this evening for Waianae Mountains- Lanai Mauka-Kahoolawe-Maui Windward West-Kohala-Big Island Interior-Koolau Leeward-Molokai Windward-Molokai Southeast- Molokai North-Molokai West-Lanai Windward-Lanai Leeward-Lanai South-Maui Central Valley North-Maui Central Valley South- Windward Haleakala-South Haleakala-Big Island South-Big Island Southeast-Big Island North.

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- Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.

Gale Warning until 6 PM HST this evening for Maalaea Bay-Pailolo Channel-Alenuihaha Channel.