Photo Credit: Brendan Stephen

West Kaua’i

Today: Mostly sunny. Isolated showers in the afternoon. Highs 78 to 85 near the shore to around 71 above 3000 feet. East winds up to 10 mph shifting to the southeast around 10 mph in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy. Isolated showers in the evening. Lows 64 to 69 near the shore to around 56 above 3000 feet. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 79 to 85 near the shore to around 71 above 3000 feet. East winds around 10 mph in the morning becoming light. Chance of rain 20 percent.

South Kaua’i

Today: Mostly sunny with isolated showers. Highs 77 to 84. East winds around 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 67. Light winds becoming east around 10 mph after midnight. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 77 to 84. East winds around 10 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Mostly sunny with scattered showers. Highs 72 to 79 in the valleys to around 64 above 4000 feet. East winds up to 10 mph. Chance of rain 40 percent.

Tonight: Partly cloudy. Scattered showers in the evening, then isolated showers after midnight. Lows 57 to 66 in the valleys to around 54 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

Sunday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 72 to 78 in the valleys to around 63 above 4000 feet. East winds around 10 mph. Chance of rain 40 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 74 to 81. Southeast winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 59 to 67. Southeast winds around 10 mph. Chance of rain 20 percent.

Sunday: Mostly sunny. Isolated showers in the morning. Highs 74 to 81. East winds up to 10 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 71 to 82. East winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows 60 to 71. East winds around 10 mph. Chance of rain 20 percent.

Sunday: Partly sunny with scattered showers in the morning, then mostly sunny in the afternoon. Highs 71 to 82. East winds around 10 mph. Chance of rain 30 percent.

Detailed Forecast

Synopsis

Gentle to locally breezes east trades to southeast winds will persist this weekend. Upper ridging over the islands will increase stability and, along with this resident dry air mass, will limit shower activity. East trades will better focus isolated showers over windward exposures and mauka slopes with the exception of select interior areas. Rain chances will increase from the west late next week.

Discussion

Upper ridging is building in from the west and this will result in stable weekend weather conditions across the Hawaiian Islands. Mid to upper level ridging nudging in from the west, along with a near one inch precipitable water air mass over the state, will significantly suppress shower activity across the region the next several days. Pre-dawn radar is very quiet with the only nocturnal light shower activity occurring far south of Kauai, possibly forming within the island plumes today and advecting west northwest within prevailing east southeast flow. Statewide breezes will likely remain weak enough to allow the development of warmth-of- the-day sea breezes to kick in. These localized breezes will move across more leeward, trade wind-protected areas or slopes. Diurnal heating will generate thicker cloud cover and trigger subsequent showers over far interior areas. Brief showers will produce low accumulations with near quarter inch amounts being confined to the higher elevations through Sunday night.
Surface high pressure located approximately 1,700 miles northeast of the islands has created a tight enough downstream pressure gradient to generally maintain gentle east trades the next several days. Increasing stability from surface ridging to the northeast and upper ridging moving in from the west, within a relatively dry boundary layer, will restrict short term shower behavior. With the island chain remaining on the southwestern periphery of the surface high through early next week, gentle winds will generally remain out of the east or southeast. Western island breezes will become more benign and variable, typically displaying more of a southerly component. Easterlies across the eastern end of the state will be slightly stronger. Weak or near calm interior winds will allow enhanced localized sea breezes to become more active once temperatures warm into the 80s. Sea breezes will promote thicker leeward clouds and increase light shower coverage over more interior communities. A better established east trade flow across the eastern half of the state will produce typical trade wind weather well into next week. Mid to upper level ridging will remain the dominate player in determining drier days heading into the second half of February. Next week's shower behavior will generally be infrequent, at best, and isolated in nature. Periodic thin bands of low to mid layer moisture advecting from the east through the middle of the month will introduce brief episodes of greater shower activity over such spots as windward Big Island and Maui County.
The extended forecast may become more active during the later half of next week. An upper low a couple of thousand miles northwest of the islands (N of 40N) will likely drag a weak cold front or shear line in the proximity of the island chain by Friday. The far distance of this low from the state and the strength of the backing high will draw into question whether this boundary makes it here on Valentine's Day or not. Ensemble guidance is still lacking any real consensus with the majority of the members from each suite depicting a a swath of the highest QPF remaining north of the island chain; thin line of rain traveling into west state Friday. Upper dynamics seem to be lacking as there doesn't seem to be much in the way of mid to upper level cooling associated with lowering heights north of the state. There should be enough higher southern latitude mid layer moisture drawn up in the southerly flow ahead of this boundary to increase Kauai and Oahu's rain probabilities (just showers) Friday. The Valentine's Day forecast still leans toward low-end moderate (30-40%) rain chances with local east southeast breezes becoming more variable going into next weekend.

Aviation

Light to moderate ESE low-level flow will persist through the weekend, with clouds and a few brief showers favoring windward and mauka slopes. The best chance for clouds and showers over interior and leeward areas will be through the afternoon periods where sea breezes form. VFR conditions will prevail, with no AIRMETs anticipated.

Marine

A weak surface ridge will remain north of the Hawaiian Islands through Wednesday. Light to moderate east-southeast winds will prevail in a fairly stable weather pattern. The Small Craft Advisory was cancelled this morning as winds and seas will remain below advisory thresholds.
A long period northwest swell currently moving through the region will continue to decline today. The HSA was cancelled this morning for north and west facing shores as the northwest swell forecast will remain just below surf advisory thresholds. Yet another long period northwest swell begins to build into the region later this morning. This next swell will peak by Saturday afternoon and evening just below High Surf Advisory (HSA) levels, and then slowly decline through Monday.
A larger northwest swell will build into the islands from Tuesday into Wednesday, with surf heights easily exceeding advisory and possibly reaching High Surf Warning levels along exposed north and west facing shores.
Surf heights along east facing shores will continue to decline. Mainly background swell energy will keep surf heights small along south facing shores.

HFO Watches/Warnings/Advisories

None.

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