West Side

Today: Mostly cloudy. Highs around 79. Light winds.

Tonight: Cloudy. Lows 66 to 73. Light winds.

Monday: Cloudy. Highs around 79. East winds up to 15 mph.

South Side

Today: Partly sunny in the morning then becoming cloudy. Highs around 83. Light winds becoming west up to 10 mph in the afternoon.

Tonight: Cloudy. Lows 66 to 75. West winds up to 10 mph in the evening becoming light.

Monday: Cloudy. Highs around 84. Light winds becoming east up to 15 mph in the afternoon.

North Shore

Today: Mostly cloudy. Isolated showers in the afternoon. Highs around 79 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy with isolated showers. Lows around 69 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Cloudy with isolated showers. Highs around 79 near the shore to around 63 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Central Maui

Today: Mostly cloudy. Highs 80 to 85. Northeast winds up to 10 mph.

Tonight: Cloudy. Lows 65 to 70. Southeast winds up to 10 mph in the evening becoming light.

Monday: Cloudy. Highs 80 to 85. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon.

Upcountry

Today: Mostly cloudy. Isolated showers in the afternoon. Highs around 60 at the visitor center to around 68 at the summit. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy. Lows 43 to 53. East winds up to 15 mph.

Monday: Cloudy. Highs around 59 at the visitor center to around 67 at the summit. East winds up to 15 mph.

East Maui

Today: Mostly cloudy. Isolated showers in the afternoon. Highs around 79 near the shore to around 64 near 5000 feet. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Cloudy with isolated showers. Lows around 69 near the shore to around 51 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 20 percent.

Monday: Cloudy with isolated showers. Highs around 79 near the shore to around 63 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Lanai City

Today: Mostly cloudy. Isolated showers in the afternoon. Highs 70 to 77. Light winds. Chance of rain 20 percent.

Tonight: Cloudy. Lows around 65. Light winds.

Monday: Cloudy. Highs 70 to 78. Northeast winds around 10 mph.

Kaunakakai

Today: Mostly cloudy. Highs 67 to 83. Light winds.

Tonight: Cloudy. Lows 57 to 71. Light winds becoming east up to 10 mph after midnight.

Monday: Mostly cloudy. Highs 68 to 84. East winds up to 10 mph increasing to 10 to 15 mph in the afternoon.

Detailed Forecast

Synopsis

Mainly isolated to scattered showers will continue for the next several days over most islands. Leeward showers will form in areas sheltered from southeast surface winds. Increasing instability aloft, along with a band of moisture, are expected to keep showers in the forecast through the middle of the week. Trades are expected to return late Wednesday into Thursday, with drier air moving in Friday and lasting into next weekend.

Discussion

The cold front that has been slowly moving toward the islands from the west will reach its closest point today, stall, then start to recede back to the west tonight. The band of moisture associated with the decaying front will be picked up by the leading edge of northeast winds building southward toward the state as a surface high strengthens Wednesday into Thursday. The band, which extends well northeast of the area, will pivot clockwise and pass over the island from the northeast Thursday night and Friday. After this, much drier air low-level air is forecast to flow out of the northeast and into the area for next weekend.
Southeast surface winds will continue through roughly Wednesday, replaced by east to northeast trades Wednesday night into Thursday. Today through Wednesday, we will see continued land and sea breezes along with the typical afternoon and evening maximum in convection in leeward areas sheltered from the southeast winds. Otherwise, we will see a few windward and mauka showers, with what is typically considered “windward” shifted a little south from its usual meaning owing to the southeast winds. Once the surface winds change to northeast, windward showers will be in their usual locations, and land and sea breezes will diminish.
The latest guidance indicates some changes in the flow aloft. We start today with weak southwest flow aloft. This weakens further through Tuesday, after which a very small upper level low forms overhead. This will bring slightly cooler temperatures aloft, and lead to an increase in instability. We will likely see an increase in showers Tuesday and Wednesday. By Thursday into Friday, a significant upper level low drops southward well to our west, inducing a ridge to develop just to our west. This will bring northwest flow aloft over the islands. The proximity of the ridge means warmer temperatures aloft, and this decreases the instability and therefore the number and strength of showers.

Aviation

Relatively light southeast winds continue today. This means a continuation of sea breezes in the leeward areas that are sheltered from the southeast prevailing winds. Showers will continue, with MVFR possible in the stronger showers. VFR is expected elsewhere.
No AIRMETs in effect.

Marine

A front will stall west of the state today and keep a surface ridge near Kauai. This should allow gentle to moderate southeast to south winds to persist across most waters and locally fresh east to southeast winds around Big Island. The ridge will retreat northward late today and Monday, allowing east to southeast winds to develop across the island chain. Easterly trade winds will strengthen Tuesday and Wednesday as broad high pressure builds to the north, and a Small Craft Advisory (SCA) will likely be needed for the typical windy waters around Maui county and the Big Island. SCA conditions may expand to additional waters Thursday as high pressure builds north of the region.
A small, medium period, west northwest (290-310 degree) swell will hold through this afternoon and bring small, below average, surf to north facing beaches. A larger, medium period, northwest (330-340 degrees) swell will arrive this evening and build through Monday, producing surf near the High Surf Advisory level along north and west facing shores. A slightly larger pulse of overlapping long period north- northwest swell will build Monday night and will likely push surf above the advisory level by Tuesday. Resulting seas may reach the 10 foot SCA across exposed waters during the peak of the swell. This swell will gradually decline through the remainder of the week.
Small surf will prevail along east facing shores today due to a lack of trade winds. A slight increase in choppy east shore surf is expected late Monday though mid-week as trade winds rebuild. Surf along south facing shores will remain tiny to small through the forecast period

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov