textproduct: Honolulu

SYNOPSIS

Breezy trades with the occasional light quick west passing shower through the day. Shower activity will primarily focus along windward exposures and upslope mauka with more organized cells passing over ridge tops and briefly wetting leeward communities. A plume of moisture moving south of the islands will clip the islands later today into early Sunday. This will increase rain chances, especially across Big Island, through Monday. Brewing western East Pacific disturbances within the tropics will need to be monitored for more organized development the next several days.

DISCUSSION

Generally light to breezy trades as the state falls in between a 1027 mb high located off the U.S. West Coast and lower equatorial pressure. Thick multi-layered cloud cover streaming up along the eastern side of a weakening west upper trough will spread west- to-east across the islands today. Despite these clouds, the afternoon will still warm up in the middle 80s to around 90 F across many lower lying spots. Trades will be welcome as wind- sheltered coastal areas feel the muggiest under low 70 F dew points. Recent area soundings depict a deep and moist enough boundary layer that will be able to support continued widely- scattered easterly showers caught up within moderate trade flow.

A moist easterly air mass in association with a tropical wave or disturbance passing south of the islands near 10N will increase cloud cover and initiate more late day through Sunday rainfall. The highest probability of precipitation is forecast to impact the Big Island and its surrounding eastern and southern waters tonight through tomorrow. Locally heavy rainfall is also possible. If enough early day sun heats up Mauna Kea and Mauna Loa's (primarily western) slopes, in tandem with the higher moisture flux from the south, there is a mentionable chance for an isolated thunderstorm or two Sunday afternoon. Once this slug of southern moisture advects west southwest of the area Tuesday, a drier air mass will briefly pass through the middle of the week. Thus, clearer skies are forecast Tuesday through Thursday with limited shower activity. Trades will not undergo much change so they will be a relief from what will be a few days of muggy, very warm weather in lower lying, more wind-protected communities.

There are increasing probabilities that an easterly wave near 10N135W may develop a low center and strengthen into something more past 48 hours. Please refer to the latest NHC forecasts concerning this potential early to mid next week evolution. The late week forecast will be dependent upon the state of the tropics. The majority of the NWP guidance, from deterministic to ensemble suites to AI, are latching on to a more active pattern this time next week. Many of the solutions are leaning toward the development of a tropical cyclone from an active western east Pacific region. While still too early to definitively discuss any details of a potential tropical cyclone, this active area will warrant close monitoring the next few days.

AVIATION

Moderate to breezy trades through the period. Low cigs and SHRA likely over windward and mauka locations. MVFR conds possible otherwise VFR prevails.

AIRMET Sierra is in effect for mtn obsc for Kauai and Oahu. Conds should improve in the mid morning hours.

AIRMET Tango is in effect for mod turb downwind of island terrain. This AIRMET will likely be need for next several days.

MARINE

Fresh to locally strong trades will continue over the next several days as an established area of high pressure remains anchored to the northeast of the state. A Small Craft Advisory has been extended through Sunday morning for the locally strong trades across the typical windy channels and waters around Maui County and the Big Island. This advisory many need to be extended even further out in time as fresh to locally strong trades continue through most of next week.

A series of small, medium- to long-period, south swells will maintain surf near seasonable norms this weekend into early next week along south facing shores. A moderate, long- period south swell will peak by mid next week and help elevate surf to near High Surf Advisory thresholds.

Along east-facing shores, expect choppy trade wind swell through the weekend as fresh to locally breezy trades persist. Surf along north-facing shores will remain flat to tiny through the period, though a small, medium- period north swell could bring a slight bump on Sunday.

Due to a combination of peak monthly high tides and water levels running higher than predicted, minor coastal flooding is possible around the daily peak tide during the afternoon hours late this weekend into early next week along vulnerable shoreline areas.

HFO WATCHES/WARNINGS/ADVISORIES

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