textproduct: Honolulu

SYNOPSIS

Trade winds will ease slightly today as Tropical Depression Moke continues moving westward, south of the islands. Showers on the northern periphery of Moke will bring wet conditions and a risk of flash flooding on the Big Island, while less rainfall is expected to impact windward sections from Maui to Kauai over the next couple of days. Trade winds will drop to moderate strength on Tuesday as Moke moves westward away from the area, with more typical trade wind weather returning for the remainder of the week.

DISCUSSION

Radar and satellite imagery shows scattered showers moving across the state. While mostly impacting windward and mauka spots some showers are making over into leeward locations. Moke is south- southwest of the Big Island with deep moisture sheared to the north of the system that is mostly skirting south of Big Island. This has kept rainfall on the lighter side with no flash flooding threats overnight. However, a flood threat will continue through this afternoon. As Moke continues to move westward, low- to mid- level flow on the Big Island will veer out of the east to the east- southeast, which could optimize orographic lift and increase rainfall on southeast slopes. Afternoon showers could produce localized flooding across the Kona Districts. As such the Flood Watch will be continued through this afternoon for the Big Island. Trades are slowly decreasing as Moke continue to move away from the state allowing the pressure gradient to relax.

On Tuesday and through the rest of the week, a trade wind pattern will return. Trades should be at moderate strength with typical windward and mauka showers occurring.

AVIATION

Tropical Storm Moke was centered nearly 400 hundred miles south of the Big Island and continued on its westward track. Rain bands from the tropical storm will impact windward Big Island through the overnight into early Monday, which will bring MVFR and periods of IFR conditions to the area. By Monday night into Tuesday, MVFR ceilings will gradually improve to VFR by Tuesday morning across the Big Island.

Trade winds are expected to be moderate to locally strong statewide. Outside of windward Big Island, showers embedded within the trade wind flow will primarily impact windward and mountain areas, bringing periods of MVFR conditions. Otherwise, VFR will prevail.

AIRMET Tango is in effect for low level turbulence downwind of terrain due to the strengthened trade winds. AIRMET Sierra is in effect for mountain obscurations over windward portion of the islands. An AIRMET for IFR conditions over portions of windward Big Island is also a possibility early this morning.

MARINE

Locally strong trades persist as Tropical Depression Moke passes south of the island chain and broad high pressure remains north of the state. Convection associated with this system will remain over the southern portion of the offshore waters as it tracks west. The Small Craft Advisory has been extended for the typical windy waters of Maui County and the Big Island.

Elevated winds and short period fresh swell generated by TD Moke have peaked over the eastern half of the state. Surf along E and ESE facing shores continue trending down as Moke advances westward. Conditions remain choppy, however, as trades persist.

Surf along S shores remains below summer norms but still slightly elevated due a lingering small, long period SSW swell. A 3-4 foot, medium to long period S swell will arrive Monday into Tuesday in maintenance of near-normal summertime surf. A similarly sized long period S swell is then poised to arrive midweek boosting surf toward the advisory threshold.

A small, medium to long period WNW swell originating from Tropical Storm Lala will fade during the next 24 to 36 hours.

FIRE WEATHER

Winds are slowly declining and will fall into the moderate category on Tuesday. Humidity remains higher than normal due to moisture on the northern periphery of Tropical Depression Moke brushing the state. Heavy rain is possible this afternoon on the southeast slopes of the Big Island and in the Kona Districts, while lower rainfall totals are expected over other windward areas of the state. A more typical summertime trade wind pattern will return by Tuesday.

HFO WATCHES/WARNINGS/ADVISORIES

Flood Watch through this afternoon for Big Island-

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