West Side

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 81 to 87. East winds up to 20 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Breezy. Lows 72 to 79. East winds up to 20 mph shifting to the northeast 10 to 20 mph after midnight.

Saturday: Breezy. Mostly sunny with isolated showers in the morning, then partly sunny in the afternoon. Highs 80 to 87. Northeast winds 10 to 25 mph. Chance of rain 20 percent.

South Side

Today: Mostly sunny with isolated showers. Highs around 89. North winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Lows 73 to 82. North winds up to 15 mph.

Saturday: Mostly sunny in the morning then becoming partly sunny. Breezy. Highs around 88. Northeast winds up to 20 mph increasing to 10 to 20 mph in the afternoon.

North Shore

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 68 to 73 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 72 to 77 near the shore to around 59 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly cloudy with scattered showers. Highs around 82 near the shore to around 70 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Central Maui

Today: Breezy. Mostly sunny with isolated showers. Highs 82 to 89. East winds up to 25 mph increasing to 10 to 25 mph in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Lows 72 to 77. East winds 10 to 20 mph.

Saturday: Partly sunny. Breezy. Highs 82 to 88. East winds 10 to 25 mph.

Upcountry

Today: Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs 65 to 83. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows around 56 at the visitor center to around 50 at the summit. East winds up to 20 mph increasing to 10 to 20 mph after midnight. Chance of rain 50 percent.

Saturday: Mostly cloudy. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 71 at the visitor center to around 73 at the summit. East winds up to 20 mph. Chance of rain 40 percent.

East Maui

Today: Partly sunny. Breezy. Numerous showers in the morning, then scattered showers in the afternoon. Highs around 82 near the shore to 68 to 73 near 5000 feet. East winds 10 to 20 mph. Chance of rain 70 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 72 to 77 near the shore to around 59 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Saturday: Breezy. Mostly cloudy with scattered showers. Highs around 82 near the shore to around 70 near 5000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Isolated showers in the afternoon. Highs 79 to 85. Northeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Lows around 72. Northeast winds up to 15 mph.

Saturday: Partly sunny. Breezy. Highs 78 to 85. Northeast winds 10 to 20 mph.

Kaunakakai

Today: Breezy. Mostly sunny with isolated showers. Highs 78 to 90. East winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Lows 64 to 79. East winds 10 to 20 mph.

Saturday: Partly sunny. Breezy. Highs 78 to 90. East winds 10 to 20 mph.

Detailed Forecast

Synopsis

A surface trough, along with moisture associated with the remnants of Norbert will continue to move westward across the state today, bringing more enhanced showers and a slight chance of thunderstorms to mainly the western end of the state. Some thunderstorm activity will also be possible this afternoon over the Kona slopes on Big Island. Drier air will move back in this weekend behind the departing trough. Moisture from the remnants of Tropical Depression 15-E may bring another round of enhanced trade showers by the middle of next week.

Discussion

Latest IR satellite loop shows convection with frequent lightning roughly 60 miles southwest of Maui. This activity is due in part to deeper moisture associated with a north to south oriented surface trough draped over the western end of the state and weak instability aloft stemming from a digging upper level trough. These features could help to bring at least some enhanced showers to the islands today, especially over windward and mauka locations. Kauai, located closest to the departing surface trough, may see the best chance of receiving heavy showers. Atmospheric instability generated by diurnal heating could lead to more showers and a slight chance of thunderstorms this afternoon over the Kona slopes on Big Island. That being said, overall instability and precipitable water values are forecast to be less than yesterday, so confidence of occurrence is slightly deflated. High resolution models, such as the WRF ARW and WRF FV3, also indicate very little in the way of widespread heavy precipitation today. Thus, it seemed warranted to cancel the Flood Watch for all islands. If any flooding does occur, but it would likely be an isolated event.
Saturday through Monday, moderate trades will help filter drier air back into the lower levels for more isolated to scattered coverage of showers during the nights or early morning hours along windward areas.
Tuesday through Thursday, there is yet another potential push (by way of moderate trades) of deeper moisture from the remnants of Tropical Depression 15-E. The GFS indicates precipitable water values could peak out between 2″ and 2.25″ across the southeast half of the state, while the ECMWF shows between 2″ and 2.5″. These values are far above seasonal normals. A short wave passing just south of the islands may provide additional lift and instability for more widespread and heavier showers.

Aviation

A trough in the vicinity of the Hawaiian Islands, in tandem with a resident moist air mass, will likely produce return periods of MVFR decks and accompanying showers. Brief periods of moderate intensity rain may lower visibilities down into MVFR, as well. Breezy trades will persist through the day with the typical light and variable breezes within wind sheltered areas.
AIRMET SIERRA will remain in effect this morning for island-wide windward exposure mountain obscuration near or above 2,500 ft.
As of 3 AM HST, no other AIRMETs are in effect.

Marine

Moisture from the remnants of Norbert and a trough aloft will bring a few thunderstorms through this morning. Trade winds will strengthen slightly through this weekend and maintain through at least the first half of next week. A Small Craft Advisory is posted for the typical windy waters around Maui County and Big Island through Friday night, and will continue into next week for these waters.
A south swell will fill in today and surf will reach near advisory levels by Saturday. Surf along east-facing shores will maintain over the next several days as the east swell from Norbert declines, but it replaced by chop from the building trade winds. Flat to tiny surf along north facing shores is expected through the forecast period.

Fire weather

Fire weather risk will remain low today due to moderate to breezy winds and increased relative humidity and moisture from the remnants of Norbert. Showers will decrease by this weekend. Inversion heights will be elevated or very weak today.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Data Courtesy of NOAA.gov