West Side

Today: Breezy. Mostly sunny with isolated showers. Highs 77 to 90. East winds up to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 71 to 77. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 77 to 90. East winds up to 15 mph shifting to the northeast in the afternoon.

South Side

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 78 to 91. North winds up to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows around 74. North winds up to 15 mph.

Tuesday: Sunny. Highs 78 to 91. North winds up to 15 mph shifting to the northeast in the afternoon.

North Shore

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to around 69 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 74 near the shore to around 60 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 82 near the shore to around 70 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 82 to 89. East winds up to 20 mph shifting to the northeast 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Breezy. Isolated showers in the evening. Lows 71 to 76. East winds 10 to 20 mph decreasing to up to 15 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 81 to 89. Northeast winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Upcountry

Today: Mostly sunny with isolated showers. Highs 58 to 74. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Isolated showers in the evening, then scattered showers after midnight. Lows 50 to 60. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Sunny. Highs around 69 at the visitor center to around 71 at the summit. East winds up to 15 mph.

East Maui

Today: Partly sunny in the morning then becoming mostly sunny. Breezy. Scattered showers. Highs around 82 near the shore to around 69 near 5000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 40 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 74 near the shore to around 60 near 5000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny with isolated showers. Highs around 82 near the shore to around 70 near 5000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 20 percent.

Lanai City

Today: Mostly sunny. Breezy. Highs 72 to 83. Northeast winds up to 20 mph.

Tonight: Mostly clear. Lows 67 to 72. Northeast winds 10 to 15 mph decreasing to up to 10 mph after midnight.

Tuesday: Sunny. Highs around 81. Northeast winds up to 15 mph.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 69 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 62 to 78. East winds 10 to 15 mph.

Tuesday: Sunny and breezy. Highs 77 to 90. East winds 10 to 20 mph.

Detailed Forecast

Synopsis

A high pressure system far to the northeast of the state will keep trade wind weather in the forecast through much of this week. We are closely monitoring an area for potential tropical cyclone development roughly 1100 miles east-southeast of the Hawaiian Islands. Based on the latest Tropical Weather Outlook from the National Hurricane Center, further development is expected by the middle of this week. The long range Hawaii forecast could change dramatically if this system moves towards the islands.

Discussion

A high pressure system far to the northeast of the state will keep trade wind weather conditions blowing through much of this week. A weak easterly wave (low level trough) moving through the islands continues to produce some unsettled clouds drifting in on the trade winds. This low level trough will continue to enhance showers, as it drifts from east to west across the state, favoring the windward mountain areas tonight before passing west of the island chain. Drier weather trends with brief passing showers are forecast from Wednesday through Friday.
We are closely monitoring a large area of disorganized convection for potential tropical cyclone development roughly 1100 miles east-southeast of the Hawaiian Islands. Based on the latest Tropical Weather Outlook from the National Hurricane Center issued at 2 AM HST, environmental conditions are conducive for further development of this system into a tropical cyclone by the middle of this week. The long range Hawaii forecast for this upcoming weekend could change dramatically if this system develops and then moves towards the islands. Stay tuned for the latest updates on this developing tropical cyclone from the National Hurricane Center online at www.hurricanes.gov and your favorite local media outlets.

Aviation

Fresh trades expected for the next several days. Low cigs and SHRA expected over windward and mauka locations. IFR/MVFR conds possible in heavier SHRA, otherwise VFR should prevail.
AIRMET Sierra is in effect for mtn obsc for windward areas of all islands due to a steady stream of showers carrying in with the trades.
AIRMET Tango is in effect for mod turb lee of terrain due to wind speeds.

Marine

High pressure to the far northeast will remain nearly stationary through midweek as moderate to locally strong trade winds persist through Wednesday. The Small Craft Advisory (SCA) has been extended through Tuesday afternoon for the windier waters and channels around Maui County and the Big Island. Borderline conditions will likely continue through at least Wednesday, which may prompt further extensions of the SCA. Later in the week, the focus will shift to the deep tropics southeast of the state. Latest guidance from the National Hurricane Center has a high chance in 7 days for a tropical cyclone to form southeast of the islands. Depending on the track, it will have differing effects on local winds, seas and weather as early as Thursday. Northeasterly winds appear likely to strengthen as the cyclone approaches during the latter half of the week, but impacts will be highly track-dependent and there is significant forecast uncertainty at this time.
Surf along south facing shores will remain near the August average today as overlapping south swells impact the islands. Surf builds slowly through the week. A moderate, long period south swell is expected to arrive late Tuesday, fill in Wednesday, and remain elevated through Friday. Surf may approach advisory levels at the peak of the swell.
Surf along east facing shores will continue to remain moderate and rough due to moderate to locally strong trade winds. Later in the week, the track of a developing tropical cyclone will dictate the potential for a swell from the southeast to east. Aside from wrapping trade wind energy, surf along north-facing shores will remain flat to tiny through the week.
Due to a combination of peak monthly high tides and water levels running higher than predicted in a few locations, a Coastal Flood Statement is in effect for minor coastal flooding around the afternoon high tide through at least Tuesday. Tides will be decreasing on Wednesday, but coastal flooding may continue to be possible around high tide for locations where water levels are running highest.

Fire weather

Fire weather conditions this week will remain just below critical thresholds this week due to the lack of stronger wind speeds. Minimum humidity levels will briefly reach criteria each day over the driest leeward areas and the lower sustained wind speeds will be the limiting factor. Temperature inversion heights near Maui and the Big Island will range from 5,500 to 6,500 feet elevation today.

HFO Watches/Warnings/Advisories

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

Data Courtesy of NOAA.gov