Photo Credit: Jason Weingardt

West Kaua’i

Today: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to around 76 above 3000 feet. Southeast winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Lows 66 to 71 near the shore to around 57 above 3000 feet. Light winds.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 86 near the shore to around 76 above 3000 feet. Light winds. Chance of rain 50 percent.

South Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85. East winds around 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Lows 66 to 72. Northeast winds around 10 mph.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs around 85. East winds up to 10 mph. Chance of rain 50 percent.

Kaua’i Mountains

Today: Mostly sunny in the morning then becoming partly sunny. Scattered showers. Highs 74 to 80 in the valleys to around 69 above 4000 feet. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Lows around 61 in the valleys to around 53 above 4000 feet. Light winds.

Tuesday: Mostly sunny with isolated showers in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 74 to 80 in the valleys to around 69 above 4000 feet. Light winds becoming northeast up to 10 mph in the afternoon. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 85. East winds up to 15 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Lows 61 to 69. Southeast winds up to 10 mph in the evening becoming light.

Tuesday: Mostly sunny in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 85. Southeast winds up to 10 mph shifting to the northeast in the afternoon. Chance of rain 50 percent.

East Kaua’i

Today: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 86. East winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 59 to 72. Light winds. Chance of rain 20 percent.

Tuesday: Mostly sunny with isolated showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 76 to 86. East winds up to 10 mph. Chance of rain 50 percent.

Detailed Forecast

Synopsis

A cold front stalling out north of the Hawaiian Islands will continue to break down the high pressure ridge to the north of the state. Lighter trade winds will allow expanded afternoon sea breezes across the island chain with a few leeward and interior showers possible in the afternoon to early evening hours. This lighter land and sea breeze wind pattern will continue through Wednesday. Trade winds will build back into the northwestern islands on Thursday and Friday as a cold front approaches the islands from the north and the ridge strengthens. Lighter winds with afternoon sea breezes will continue into the weekend for Maui and the Big Island.

Discussion

The regional satellite imagery this morning continues to show a weakening cold front stalling out just north of the state, and another cold front is approaching the islands farther to the northwest of the region. Cold air advection behind these fronts will continue to break down the high pressure ridge north of the islands resulting in lighter trade winds through Wednesday. These lighter large scale winds will allow local scale afternoon sea breezes to expand in coverage, producing just a few leeward and interior showers favoring the afternoon to early evening hours. A high pressure ridge in the upper levels around 500 mb (or 18,000 feet above the surface) will tend to limit shower potential. These hybrid light trade winds and sea breezes will continue through Wednesday for the northwestern half of the state, and continue into next weekend for Maui and the Big Island.
Longer range model guidance for the Thursday through Friday time period shows a weakening cold front moving into the islands from the north with a high pressure ridge building in behind the front. Increasing shower trends are possible during this period if the front moves into the island chain as the current model runs predict. Model guidance this time of year tends to be more aggressive with moving these cold fronts into the islands and the possibility remains that this front will stall out before it moves through most of the state. That said, Kauai has the highest chances for increasing shower trends with elevated chances for bands spreading to Oahu during the same time period. The frontal cloud band will likely break apart before reaching Maui or the Big Island. Chances for enhanced rain over Molokai and Lanai are running just behind Oahu at this point in time.
Lighter south to southeasterly winds are expected to develop by next weekend as extended range model solutions show a cold core low dropping into the region from the north. Island by island weather impacts will have to wait until the forecast time period grows shorter as a 100 mile difference in the cold core low location may significantly alter weather impacts for the western half of the state. Stay tuned, as this long range weather pattern evolves over time.

Aviation

Light to locally moderate trades will continue today, allowing for the development of local land and sea breezes. Isolated to scattered showers will continue across windward sections early this morning, then diurnal heating will allow local sea breezes to initiate isolated showers across a few leeward and interior areas this afternoon.
No AIRMETs are currently in effect nor expected through the next 24 hours.

Marine

A front passing by well to the north of the islands will keep the trades in the light to moderate range through mid week, strongest over the eastern end of the state. The tail end of a weakening front could push southward into the western islands Thursday and Friday, with a new high building in behind the front. This may strengthen the trades back to moderate and fresh levels over the western end of the state, with lighter trades prevailing over the eastern isles. The trades appear to ease and become disrupted again next weekend as a new front approaches from the northwest.
The latest nearshore and offshore buoy observations indicate that the current northwest swell will hold relatively steady today, remaining just below advisory levels along north facing shores. A new much larger long-period northwest swell will begin to fill in later today, then rapidly build to advisory levels along most north and west facing shores of the smaller islands tonight and to warning levels on Tuesday. The swell will peak at extra large levels Tuesday night and Wednesday, before gradually declining through the remainder of the work week and into the upcoming weekend. For the Big Island much of this swell will be blocked by the smaller islands, however, surf will likely rise to advisory levels along west facing shores late tonight through Wednesday night and possibly Thursday. Surf along north facing shores of the Big Island will likely reach advisory levels as well late Tuesday through Thursday and possibly Friday.
This swell will also build seas to Small Craft Advisory levels across much of the marine area Tuesday through Wednesday night, and possibly longer for portions of the coastal waters.
Along south facing shores, a series of south-southwest swells will keep surf well above the October average through much of the work week. East shore surf will remain very small during the next 7 days in areas not exposed to any wrap from the northwest or the south.

HFO Watches/Warnings/Advisories

None.

Data Courtesy of NOAA.gov