Photo Credit: Sebastien Gabriel

West Kaua’i

Today: Mostly sunny. Highs 86 to 93 near the shore to around 78 above 3000 feet. Northeast winds up to 15 mph shifting to the south in the afternoon.

Tonight: Partly cloudy. Lows around 71 near the shore to around 61 above 3000 feet. Northeast winds up to 10 mph.

Saturday: Mostly sunny. Highs 86 to 92 near the shore to around 77 above 3000 feet. Northeast winds up to 10 mph shifting to the south in the afternoon.

South Kaua’i

Today: Mostly sunny. Breezy. Isolated showers in the morning. Highs 85 to 92. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 70 to 75. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny. Isolated showers in the morning. Highs 85 to 91. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Kaua’i Mountains

Today: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 85 in the valleys to around 69 above 4000 feet. East winds up to 15 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 68 in the valleys to around 59 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

Saturday: Partly sunny with scattered showers in the morning, then mostly sunny with isolated showers in the afternoon. Highs 75 to 84 in the valleys to around 68 above 4000 feet. East winds up to 15 mph. Chance of rain 50 percent.

North Kaua’i

Today: Mostly sunny with isolated showers. Highs 78 to 89. East winds up to 15 mph shifting to the northeast in the afternoon. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 66 to 74. East winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 77 to 89. East winds up to 15 mph. Chance of rain 20 percent.

East Kaua’i

Today: Mostly sunny with isolated showers. Highs 76 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 78. Northeast winds up to 10 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 75 to 88. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Detailed Forecast

Synopsis

Moderate trade winds will continue to blow across the islands through next week Monday as high pressure ridge north of the main Hawaiian Islands weakens. Terrain sheltered leeward areas will see upslope sea breezes during the day and downslope land breezes at night. Brief passing showers will drift over windward and mountain areas over the next several days, especially from the overnight through early morning hours.

Discussion

Water vapor satellite imagery this morning shows dry and stable subsidence (downward vertical motions) over the Hawaii region. Infra-red imagery continues to show a large band of stable stratocumulus clouds drifting into the windward slopes of each island on the trade winds. Passing light showers are developing along windward slopes of each island as shown on local radar imagery. Upper air balloon soundings from 2 AM HST this morning show temperature inversion heights remain in the 5,000 to 7,000 foot range from Lihue to Hilo respectively. Model cross sections show these low stable inversion height trends continue through the weekend, which will cap low level cloud heights and keep shower activity to a minimum. The best chances for measurable rain will occur along windward mountain slopes, mainly in the typical overnight to early morning time periods. Rainfall amounts for most locations will likely be less than 0.25 inches in any 12 hour time period. This typical summer dry trade wind pattern will continue through Monday.
High pressure far to the north of the state will build back in starting on Monday night. Long range models show a slight increase in trade wind speeds into the moderate to locally breezy range. These moderate to locally breezy trade winds will continue through Wednesday. Shower trends may increase for eastern portions of Maui and the Big Island from Monday night into Tuesday morning as a weak wind speed convergence band moves into the eastern half of the state. Oahu and Kauai will see little change in rainfall.
In the long range forecast for next week, there is currently a low chance for another tropical cyclone to form over the next 7 days in either the Eastern or Central Pacific basins according to the National Hurricane Center in Miami, Florida. Global weather models suggest that if this cyclone develops, then it should pass south of the main Hawaiian Islands around the middle of next week. This is not the same setup that we had for Dora, as the high pressure system far north of the Hawaiian Islands is much further north, resulting in a completely different weather pattern with much lower wind speeds. Stay tuned.

Aviation

Moderate trade winds will continue through twenty-four hours and beyond. Scattered light showers are possible statewide, but are expected to favor east facing slopes and coasts. Brief MVFR conditions are to be expected this morning, especially along the windward coast of the Big Island from Hilo northward. VFR conditions will otherwise prevail statewide.
Light sea breezes will return to leeward Big Island this afternoon. Weak cumulus build-ups will redevelop over the island's south and west facing slopes later today, but a strong trade wind inversion around 08 kft will limit vertical growth. Any leeward showers will be light in intensity and limited in coverage.

Marine

A surface ridge far north of the state has weakened slightly since Thursday. However, a recent scatterometer pass over the area shows winds of at least 25 knots in the Alenuihaha Channel. As a result, a Small Craft Advisory has been issued for those waters today. Expect the ridge to continue weakening as it shifts slowly toward the south from later today and tonight into this weekend. Therefore, the latest forecast indicates the trade winds will ease into the moderate to fresh category this weekend. A new surface high is forecast to build far northeast of the islands next Tuesday, which may bring a period of locally strong trade winds.
Surf along south facing shores remains slightly elevated early this morning due to a medium-period south-southwest swell. Expect a gradual downward trend in the south-southwest swell from tonight into this weekend. The current moderate, choppy surf along east facing shores will steadily lower from tonight through this weekend as the trades weaken locally, and upstream of the state.
A distant fetch of northwest winds associated with a gale low near the Aleutian Islands may send a small north-northwest swell toward the islands early next week. If this swell arrives, it may cause surf to trend up slightly beyond the typical summertime flat conditions along exposed north facing shores starting next Monday.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel.

Data Courtesy of NOAA.gov