1-3 foot
1-3 foot
1-3 foot
1-4 foot

Trades will trend down into the light to moderate range by the end of the weekend as high pressure shifts eastward over the northeast Pacific and Hurricane Mariam tracks northward far northeast of the marine area. The overnight ASCAT pass, however, did reflect fresh trades holding in place over the marine area, mainly the channels and typically windier locations. Fresh to strong trades are forecast to return Tuesday through midweek. Forecast confidence begins to lower beyond Wednesday due to varying solutions from cycle to cycle for Hurricane Norman as it approaches the region.

Surf along east facing shores will remain up through the weekend due to a combination of fading short-period trade wind energy and 10-12 second energy filling in from Hurricane Miriam. This swell will become reinforced early next week as Hurricane Norman approaches the region. Provided Norman will continue westward at a higher latitude, the Big Island shouldn’t have as much of an impact on the smaller islands with regard to shadowing. As a result, surf could exceed advisory levels for all east facing shores and potentially near warning levels through the midweek time frame along east facing shores.

Surf along south facing shores should come up through the day today as a new south-southwest swell fills in from recent southern hemisphere activity. Spectral density plots from the offshore buoys a couple of hundred nautical miles south of the islands are depicting a small jump in energy within the 14-15 sec band. This should hold through the weekend below advisory levels, then fade into early next week.

Hawaii Wave Height Model

Tide Predictions

High tide at Kahului was 1.73 foot at 2:00 PM early this afternoon, dropping to a low of 1.19 foot at 2:00 PM early this afternoon, then rising to a high of 1.64 foot at 2:00 PM early this afternoon.

The sunrise was at 06:08 am this morning and will set at 06:42 pm this evening. The Moon is currently 21 days old, and is in a Last Quarter phase. The next Waning Crescent will occur at 6:02 PM on Sunday, September 9th.

Hawaii Wind Report

Maui Weather

°/°
Wind: n/a at 0 mph
Sunrise:
Sunset:
current observations as of 7am October 20th, 2018

Weather Outlook for Saturday, 1st September 2018

Summary

A weakening trade wind pattern will prevail through the holiday weekend, with clouds and passing showers mostly favoring windward and mountain areas. Increasing moisture combined with strengthening trade winds may cause more widespread showers over the state beginning Monday night and Tuesday. Hurricane Norman is forecast to move into the Central Pacific basin late Monday night, but it is much too early to determine if Norman will have any direct impact on Hawaii during the middle and later part of next week.

Detailed Discussion

Moderate trade winds prevail across the state on this early Saturday morning. Satellite and radar loops show areas of clouds and widely scattered showers over some windward areas, mainly in the western half of the state. Rain gauges show that the most rain during the past six hours has occurred over windward Kauai and Oahu, with up to a quarter inch measured at a few spots. Little or no rainfall has occurred across Maui County and the Big Island during that time. There is relatively little cloudiness upstream of the islands, as a dry airmass remains in place over the region. The 12Z soundings showed typical trade wind inversions based around 8000 feet, with below normal PW values between 1.2 and 1.3 inches. MIMIC-TPW satellite imagery shows a rather dry airmass surrounding most of the state, with slightly greater moisture around Kauai where showers have been more prevalent during the night. Surface analysis shows high pressure centered far north-northeast of the state, with weakening Hurricane Miriam centered about 900 miles east of the Big Island and moving northward. Aloft, water vapor imagery depicts a well- defined mid/upper level trough located several hundred miles northeast of the state. Northerly flow aloft around the western side of this trough is helping to provide the rather dry airmass currently over the islands, while southerly flow to the east of the trough is steering Miriam northward well to our east.

There is no significant change in the forecast philosophy through the holiday weekend. Trade winds will gradually decrease, as weakening Miriam tracks well to the east and northeast of the state and disrupts the large-scale pressure pattern. A dry airmass is forecast to remain in place over the eastern half of the state through Sunday, with somewhat greater moisture over western sections. This will keep rain chances highest over windward Oahu and Kauai, with below normal rain chances even over windward areas of Maui County and the Big Island. Higher PWs will begin to spread westward across the Big Island and eventually Maui County Sunday night and Monday, while the drier airmass shifts over Oahu and Kauai. This will cause the highest rain chances to shift to windward parts of the Big Island and Maui County.

Trade winds should begin to increase again on Tuesday as the remnants of Miriam dissipate to our north. Both the GFS and ECMWF show an area of enhanced moisture embedded in the trade wind flow moving through the entire state on Tuesday, which should cause a wetter trade shower pattern, with some showers possibly spilling over leeward on the smaller islands. Forecast uncertainty increases thereafter, with Hurricane Norman forecast to approach the region from the east by midweek. The latest GFS and EC runs continue to show Norman passing northeast of the state late next week, with the last couple of GFS runs bringing the system considerably closer to the islands than does the EC. It is much too early to determine if Norman will have any direct impact on Hawaii during the middle and later part of next week. For now, we show increasing trade winds through Wednesday, then trades decreasing from east to west across the state thereafter as Norman passes to the northeast of the islands. It is possible that we may shift into a land and seabreeze pattern by next weekend.

Central Valley (Kahului, Spreckelsville):

Mostly clear. Lows 67 to 73. Northeast winds up to 15 mph in the evening becoming light.

Leeward West (Lahaina, Ka`anapali):

Mostly clear. Lows 66 to 74. Northeast winds 10 to 15 mph shifting to the east after midnight.

Windward West (Wailuku, Waiehu):

Partly cloudy. Isolated showers in the evening. Lows 58 to 71. Northeast winds up to 15 mph. Chance of rain 20 percent.

Windard Haleakala (Hana, Haiku, Makawao):

Partly cloudy in the evening then becoming mostly cloudy. Isolated showers. Lows around 70 at the shore to around 53 at 5000 feet. Southeast winds up to 10 mph. Chance of rain 20 percent.

Leeward Haleakala (Kihei, Wailea, Makena):

Mostly clear. Lows around 70 at the shore to around 56 upcountry. Light winds.

Haleakala Summit

Mostly clear. Lows around 46 at the visitor center to around 42 at the summit. Light winds.