Photo Credit: Travis Guthrie

West Side

Today: Breezy. Sunny with isolated showers. Highs 82 to 88. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 68 to 74. East winds 15 to 25 mph. Chance of rain 30 percent.

Tuesday: Breezy. Sunny with isolated showers. Highs 81 to 87. East winds 10 to 20 mph. Chance of rain 20 percent.

South Side

Today: Sunny and breezy. Highs around 88. Northeast winds 10 to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 69. Northeast winds 10 to 20 mph.

Tuesday: Sunny and breezy. Highs around 87. Northeast winds 10 to 20 mph.

North Shore

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 79 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Central Maui

Today: Sunny and breezy. Isolated showers in the morning. Highs 84 to 90. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear with isolated showers. Lows 66 to 71. Northeast winds 10 to 15 mph. Chance of rain 20 percent.

Tuesday: Sunny and breezy. Isolated showers in the morning. Highs 83 to 89. Northeast winds 15 to 20 mph. Chance of rain 20 percent.

Upcountry

Today: Sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 61 at the visitor center to around 58 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tonight: Partly cloudy with scattered showers. Lows around 46 at the visitor center to around 42 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

Tuesday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 61 at the visitor center to around 58 at the summit. East winds 10 to 15 mph. Chance of rain 50 percent.

East Maui

Today: Breezy. Partly sunny with scattered showers. Highs 80 to 86 near the shore to around 69 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 65 to 72 near the shore to around 53 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Tuesday: Partly sunny with scattered showers. Highs 79 to 85 near the shore to around 68 near 5000 feet. East winds 10 to 15 mph. Chance of rain 50 percent.

Lanai City

Today: Breezy. Mostly sunny with isolated showers. Highs 73 to 81. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Breezy. Isolated showers after midnight. Lows around 68. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Sunny and breezy. Isolated showers in the afternoon. Highs 73 to 81. East winds 10 to 20 mph. Chance of rain 20 percent.

Kaunakakai

Today: Sunny and breezy. Highs 74 to 85. Northeast winds 10 to 20 mph.

Tonight: Breezy. Mostly clear with isolated showers. Lows 64 to 74. Northeast winds 10 to 20 mph. Chance of rain 20 percent.

Tuesday: Sunny and breezy. Highs 74 to 85. East winds 15 to 20 mph.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will focus brief showers mainly over windward and mauka areas into early Wednesday. The greatest coverage of trade showers will be during the overnight and early morning hours. Increasing moisture is expected to enhance trade showers over windward facing sections from late Wednesday through the end of the new work week. Locally strong trade winds may transport brief trade showers over to the leeward sections of some of the smaller islands starting Thursday.

Discussion

A 1036 mb surface high pressure system is located near 44N 157W, or about 1600 miles north of Honolulu. The pressure gradient south of this feature is producing moderate trade winds across the region early this morning. Loops of satellite imagery and radar reflectivity data show scattered low clouds and spotty showers moving into the windward sides of some of the islands.
The forecast guidance shows the surface high pressure system will build as it moves rapidly toward the south-southeast during the next few days. This will tighten the pressure gradient across the state from later today and tonight into mid-week. This will cause the trade winds to become locally breezy during the next day or two. In addition, expect a general drying trend with a windward and mauka shower pattern. In this regime, the greatest coverage of trade showers will likely be during the overnight and early morning hours into early Wednesday. Also, expect clouds and isolated showers to develop over some of the upslope sections of the Leeward Big Island each afternoon, followed by gradually clearing during the evening hours.
Starting late Wednesday, increasing moisture may result in greater windward and mauka shower coverage. In addition, locally strong trade winds starting Thursday may transport brief trade showers over to the leeward sections of some of the smaller islands, especially at night. The forecast models continua to show some differences in moisture availability heading into next weekend. However, based on recent trends, it appears that the surface and upper-level features that are expected to organize to the northwest of the region might allow increased moisture, and some enhancement of trade showers next weekend.

Aviation

Moderate trade winds and a typical pattern of rainfall will persist today, though some increase in winds are expected into Tuesday. Brief MVFR conditions will be confined to windward slopes of all islands, as well as over the Kona slopes of the Big Island during the afternoon and evening hours. Otherwise, VFR will prevail. No SIGMETs are in place, and none are expected through the afternoon. Conditions will be border line for AIRMET Tango due to some turbulence over and downwind of terrain today, and an AIRMET may be needed tonight or Tuesday.

Marine

Expect moderate to fresh trade winds to continue today across all Hawaiian waters. A high pressure system will build in from the north tomorrow, producing moderate to strong trade winds from Tuesday onward. Wind speeds will approach Small Craft Advisory (SCA) thresholds tonight, and we will monitor closely for the passably of a SCA issuance. Otherwise wind speeds will reach SCA thresholds for the typical windier waters around Maui and the Big Island starting on Tuesday. The coverage of SCA conditions may expand by Thursday to cover additional coastal water zones.
We will continue to see small surf along north facing shores during the next few days. Another small pulse from the north- northwest is possible later today into Tuesday followed by a slightly larger swell from the northwest late Thursday into Friday.
A series of small long-period south swells will continue to keep fun size surf along south facing shores through the week. Surf should trend down this weekend with mainly background energy by early next week. Surf heights along west facing shores will remain small through the week with a bit of south and northwest swell wrap keeping west side surf heights above flat levels.
Surf along east facing shores will remain near seasonal averages for the next several days. East facing surf heights should see an increase of size and chop along eastern exposures from Wednesday to Friday as trade wind speeds increase.

HFO Watches/Warnings/Advisories

None.

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Data Courtesy of NOAA.gov