Hawaii Island Weather Update for May 5th, 2019
Drier conditions are slowly taking over. Moderate to Heavy showers were reported all over West Hawaii overnight and has since dissipated.
Synopsis
The cold front that quickly moved down the island chain Saturday is slowly moving over the Big Island early this morning. This boundary combined with a secondary band of showers quickly advancing down the island chain will keep the rain chances up across the eastern half of the state today. Some showers may be heavy at times with gusty winds due to a combination of the front and an upper low approaching from the north. Drier and cooler air along with gusty northwest winds will fill in today from west to east, with trade winds unlikely to make a return until later this week.
Discussion
Early morning observations, satellite data and radar trends showed the front that quickly moved through the islands Saturday now over the Big Island slowly shifting eastward. A secondary band of showers associated with a post-frontal trough is quickly moving through from west to east approaching Maui County. These surface features combined with an anomalously deep upper low dropping south into the area will keep the rain chances up across the eastern half of the state today. Some showers will be heavy at times and capable of producing gusty winds up to 45 mph. Guidance continues to depict the upper low stalling just north of the islands today, then drifting east-southeastward through tonight. Although a storm or two can't be ruled out over the northern Maui County and Big Island windward waters, the better dynamics and forcing for ascent will remain positioned just north of these waters today.
Much drier and unseasonably cooler air with gusty northwest winds will fill in from west to east today through tonight as the front continues eastward. Temperatures will only manage to hit the mid- to-upper 70s through the afternoon hours today, then dip into the low-to-mid 60s tonight into Monday morning for the overnight lows. Dew points 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 from late tonight 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
The Flood Advisory that was issued for Hawaii Island has since expired as moderate to heavy showers that came over island slowly dissipate and bringing in drier conditions behind it.
HIGH WIND WARNING REMAINS IN EFFECT UNTIL 6 PM HST THIS EVENING - WINDS: West 50 to 80 mph with localized gusts to 100 mph. - TIMING: Through this afternoon, and possibly holding through tonight. - 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 at Hale Pohaku Visitor Information Center due to high winds ranging from 86-98 mph. The National Weather Service has issued a High Wind Warning for Big Island summits continuing through 6:00 p.m. this evening. Summit conditions also include fog, high humidity, and below freezing temperatures.