textproduct: Honolulu

UPDATE

Latest trends show that moderate turbulence has subsided across and along leeward sites of the islands, therefore have canceled AIRMET Tango.

SYNOPSIS

Relatively benign conditions with breezy east to southeast winds will persist through the weekend amidst an approaching front stalling just west of the islands. This pattern will favor showers along southeast and east-facing slopes with sea breezes, and sea breeze showers, potentially developing within sheltered leeward and interior areas. Strengthening southerly flow is anticipated to pull deep tropical moisture northward over the islands next week, bringing an increasing chance for a wetter and more unsettled pattern.

AVIATION

Trade winds will continue for Thursday, pulling slightly more southeasterly during the day before returning more easterly Thursday night. Intermittent windward and mountain shower activity will continue, and with it periodic MVFR conditions for those impacted sites under showers, but otherwise expect VFR to prevail.

MARINE

High pressure situated far to the northeast of the Hawaiian Islands will produce fresh to strong east-southeasterly trade winds today. Winds ease slightly Thursday night into Friday as a front passes north of the islands, and winds may even shift southerly just west of Kauai for a time before fresh to strong east-southeast winds return Friday night. The Small Craft Advisory (SCA) has been extended through Friday evening for most of the waters around the Big Island and Maui, where winds are typically enhanced by terrain interaction. This general wind pattern is likely to hold through the weekend. Then, a large low pressure system approaching from the west this weekend will stalls out northwest of the islands beginning early next week. Winds veer more southerly in response to the low's cold front making a close approach, or even entering the northwest offshore waters, by mid- week. Strong southerly winds will be possible depending on how close the cold front gets to the islands.

Surf along north- and west-facing shores will remain small as a series of small long- to medium-period west to northwest swells reach the Hawaiian Islands over the next week or so. The current northwest swell reaches a nadir today as very little wave energy is being detected from that direction by buoy observations this morning. The forerunners of a small west-northwest swell are anticipated to arrive this afternoon/evening, and peak Friday night, followed by another small northwest swell that maintains the small surf through the weekend. A compact storm-force low currently just off the coast of Japan will likely produce another small west-northwest swell early next week.

Choppy east shore surf will remain near seasonal averages as east-southeasterly trade winds vary minimally over the next few days, with a chance for a slight increase over the weekend. Surf along east facing shores then declines early next week as winds veer southerly. Surf along south facing shores will remain small through the weekend, but may increase and become choppier with the shift to a more southerly wind direction early next week. A small long-period south swell is also possible around Tuesday of next week.

PREV DISCUSSION

Weather conditions remain relatively benign with breezy east to southeast winds through the weekend. Overall low-level flow is anticipated to remain east-southeast during this time, leading to showers favoring southeast- and east-facing slopes. Sea and land breezes over sheltered leeward and interior areas are possible, and could result in shower development during the afternoon, followed by clearing at night. Overall rainfall amounts through the weekend are expected to remain light with little impact. Model guidance continues to portray a front stalling just west of the islands this weekend as it encounters the deep ridge just northeast of the islands.

Things become a bit more interesting by early next week as model guidance continues to support an area of low pressure moving toward the state, resulting in low-level flow veering more southerly and strengthening. This flow is expected to pull tropical moisture northward over the Hawaiian Islands by midweek next week, persisting through the outlook period. Current model total precipitable water (PWATs) normalized anomalies show nearly three standard deviations above normal, equating to 40 to 46 mm PWATs (1.6 to 1.8 inches, respectively). This moist southerly flow, in conjunction with instability associated with nearby upper-level disturbances, could support a wetter and more unsettled pattern through much of next week.

Latest model guidance has shown an improved agreement regarding the overall pattern evolution next week, leading to increased confidence. However, uncertainty remains regarding the exact location of the deepest moisture and the strength of the southerly winds, especially given the long range time frame.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 PM HST Friday for Maui County Windward Waters-Pailolo Channel-Alenuihaha Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.