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Hawaii Weather Outlook Update for May 5th, 2019

Waterspout was spotted offshore Kona International Airport at 6:15 pm this evening. Event only lasted for 5 mins and dissipated. Photo taken from O'oma Beach.

(Photo Caption: Benjamin Agdeppa - HIRSC Admin)


The cold front that has been moving down the island chain today has begun to move over the Big Island this evening and weaken. Instability associated this boundary and a potent upper low dropping south toward the islands, however, will keep the chances for moderate to heavy showers and gusty winds up overnight, mainly along and ahead of the front over the Big Island. Elsewhere, a post- frontal trough, currently north of Kauai, will drive another line of moderate showers quickly through the islands from west to east overnight. Drier and cooler air will fill in behind this trough late tonight through Monday, with trade winds unlikely to make a return until Thursday.


Evening observations, satellite data and radar trends showed the front that has quickly moved through the islands today beginning to move over the Big Island and weaken. The anomalously deep upper low responsible for these out of season conditions today is lurking off to the north drifting southward toward the state. The line of showers along the front that has moved ashore from Kailua-Kona to the Hamakua coast this evening will continue eastward slowly through the evening hours and diminish. A special weather statement was issued for this line moving ashore due to the potential for wind gusts up to 45 mph. Elsewhere, gusty northwest winds have filled in behind the front over the smaller islands with scattered showers moving through, mostly favoring northern slopes. Additionally, a post-frontal trough, currently located north of Kauai, is forecast to quickly advance down the island chain overnight into Sunday morning, which will keep the rain chances up over the state.

Upper heights will steadily lower across the region as the aforementioned upper low drops south to an area just north of the islands overnight. Although a storm or two can't be ruled out over the windward waters, the better dynamics and forcing for ascent will remain positioned just north of these waters of Maui County and the Big Island.

Much drier and unseasonably cooler air will fill in behind this post- frontal trough Sunday and Sunday night. Temperatures will only manage to hit the mid-to-upper 70s through the afternoon hours, then dip into the low-to-mid 60s Sunday night into Monday morning for the overnight lows. Dewpoints are forecast to drop into the 50s through this time due to the drier air.

As the upper level low fills and lifts off to the northeast through the first half of the week, it will leave a weak trough of low pressure over and around the state. Light and variable winds will be the result each day through Wednesday, which will give way to a land and sea breeze regime. A return of light to moderate trades will become a possibility through the second half of the week.

Weather Advisories

HIGH WIND WARNING REMAINS IN EFFECT UNTIL 6 PM HST SUNDAY - WINDS: West 50 to 80 mph with localized gusts to 95 mph. - TIMING: Through Sunday afternoon, and possibly holding through Sunday night. - IMPACTS: Travel to the summits will be difficult or dangerous. PRECAUTIONARY/PREPAREDNESS ACTIONS A High Wind Warning means that winds at the summits are expected to be at least 56 mph, with gusts over 66 mph. Take necessary precautions to protect property. Travel to summit areas should be delayed until winds subside.

Mauna Kea Access Road remains closed to the public at Hale Pohaku Visitor Information Center due to high winds in excess of 90 mph and gusting to over 100 mph, at times exceeding 113 mph. The National Weather Service has issued a High Wind Warning for Big Island summits continuing through 6:00 p.m. Sunday. Summit conditions also include fog, high humidity, and below freezing temperatures.

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