textproduct: Honolulu

SYNOPSIS

Light to occasionally breezy trades with a slight uptick in windward and upslope mauka clouds and showers later today into evening. Recent trade behavior will remain steady through mid week with a slight strengthening of winds expected later this week. Rain coverage may increase Tuesday into Wednesday with increased moisture moving in from the east. Tropical Cyclone Fausto will remain far east and away from our offshore waters next weekend but may still influence our trade flow pattern going into early next week.

DISCUSSION

A quiet and fairly dry start to Monday as upper ridging engulfing the central Pacific provides the greater subsidence and stability required in maintaining drier weather conditions. Higher moisture advancing toward us from the east will likely boost statewide shower frequency and coverage the next couple of days. This morning's slightly below normal precipitable water values of 1.1" to 1.2" will be on the rise back to near normal levels of around 1.4" by tomorrow in response to greater mid layer moisture advection. Higher low to mid layer humidity will be the impetus to increased shower frequency from later today through Wednesday. A subtle lift in modeled boundary layer thickening, or lifted inversion heights, from this morning's 6.5 kft to 7 kft heights to Tuesday's near 10 kft depth signals higher probabilities of more areawide early week rainfall. Drier air following this moist air mass will be noticed in lessened late week shower activity. After several days of light to moderate trades, a more favorable orientation of the pressure gradient back from a large surface high far north of the area will keep the central Pacific gradient tight enough to support more fresh late week trades.

Tropical Storm Fausto, currently located several hundred miles west southwest of southwestern Mexico, is steadily strengthening. Fausto is expected to achieve hurricane strength this evening with a northwest becoming more westerly track through Wednesday. Deterministic model guidance has Fausto reaching 140W in about a week with it weakening along its northwesterly track as the cyclone encounters western ridging and cooler waters. If TC Fausto stays on a northwesterly track, localized trade flow will be interrupted with much weaker trades expected early to mid next week.

AVIATION

Moderate trades will continue through the forecast period. VFR conditions will prevail except isolated MVFR conditions over windward and mauka areas in clouds and showers.

No AIRMETs are in effect and none are anticipated through the forecast period.

MARINE

The trade winds will hold at mostly moderate speeds today through Tuesday, then restrengthen back to fresh and locally strong speeds Wednesday through Friday as high pressure strengthens north of the island chain.

The current long period south swell will continue to build today, then peak near the advisory level tonight into early Wednesday. A High Surf Advisory will likely be required as the swell peaks. This swell with then slowly fade during the middle of the week, but will be followed by a new long period south swell arriving on Thursday, which will keep surf elevated above the summertime average through the weekend.

Surf along east-facing shores will remain slightly below seasonal levels today through Wednesday as the trades ease upstream of the islands. East shore surf should then build back close to seasonal levels late this week and through the weekend as stronger trades return over and upstream on the islands. Additionally, swell generated by former Tropical Cyclone Elida may give a slight boost to east shore surf during the middle of the week.

Surf along north-facing shores will remain at flat to tiny levels through the weekend.

HFO WATCHES/WARNINGS/ADVISORIES

None.