Hilo

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 85 near the shore to 63 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 61 to 72 near the shore to 53 to 58 at 4000 feet. North winds up to 10 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 78 to 86 near the shore to 64 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Kona

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 84 to 89 near the shore to around 70 near 5000 feet. Southwest winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows around 74 near the shore to 51 to 57 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 84 to 89 near the shore to around 69 near 5000 feet. Light winds. Chance of rain 20 percent.

Waimea

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 63 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 64 to 85. East winds up to 15 mph. Chance of rain 20 percent.

Kohala

Today: Mostly sunny in the morning then becoming partly sunny. Isolated showers. Highs 63 to 84. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 62 to 72 near the shore to 55 to 62 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Saturday: Mostly sunny with isolated showers. Highs 64 to 85. East winds up to 15 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Highs around 85 near the shore to around 68 near 5000 feet. East winds up to 15 mph.

Tonight: Partly cloudy. Lows around 74 near the shore to around 54 near 5000 feet. East winds up to 15 mph.

Saturday: Mostly sunny. Highs around 85 near the shore to around 67 near 5000 feet. East winds up to 15 mph.

Puna

Today: Partly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs 77 to 85 near the shore to 63 to 71 at 4000 feet. Northeast winds up to 10 mph. Chance of rain 50 percent.

Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows 61 to 72 near the shore to 53 to 58 at 4000 feet. North winds up to 10 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 78 to 86 near the shore to 64 to 71 at 4000 feet. Northeast winds up to 15 mph. Chance of rain 50 percent.

Waikoloa

Today: Mostly sunny. Highs 83 to 91 near the shore to 66 to 73 above 4000 feet. Northwest winds up to 15 mph shifting to the northeast in the afternoon.

Tonight: Mostly clear. Lows around 74 near the shore to 51 to 56 above 4000 feet. East winds up to 10 mph.

Saturday: Sunny. Highs 83 to 91 near the shore to 67 to 73 above 4000 feet. North winds up to 10 mph.

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.

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Data Courtesy of NOAA.gov