Tropical Storm Conditions Possible This Weekend
Alerts (as of 1:00 a.m.)
A Tropical Storm Warning is posted for Hawaii County.
A Flash Flood Watch has been issued by the National Weather Service. It goes into effect late Friday night and will be posted through Sunday afternoon. Tropical Storm Darby is expected to continue approaching the Hawaiian Islands. The forecast is still highly dependent on the track and intensity of the system, however, there is a possibility for intense rainfall and flash flooding this weekend. East to southeast facing slopes are at greatest risk.
When rainfall episodes of this intensity occur, flooding could occur even outside of normal flood zones. Keep in mind, flooding on roadways can make driving very dangerous and roads impassable. Two feet of water is enough to sweep your car away. Debris can clog waterways. Never try to cross fast-flowing water on foot.
A High Surf Warning is also posted for the east facing shores of the Big Island from 6 a.m. Friday to 6 a.m. Sunday. Surf is forecast to build to 12 to 20 foot faces Friday with higher sets at the best exposures. Waves this big can cause coastal flooding and lead to dangerous ocean conditions. Powerful currents are also a concern and large breaking waves can impact harbor entrances and channels.
**Click directly on the images below to make them larger. Charts include: Big Island high/low forecasted temperatures, projected winds, chance of cloud cover, projected localized weather conditions, vog/SO2 forecast and expected wave heights.**
Tropical Storm Darby is approaching the Hawaiian Islands from the east over the next couple of days. The system could bring stormy weather this weekend. As Darby gets closer the peripheral moisture will affect windward areas first. More intense rain and wind is expected to follow as the system progresses.
There is still a lot of uncertainty with the forecast. Just slight changes to track and intensity can mean big differences in the forecast philosophy. We will continue to keep an eye on this and bring you firmer forecasts. For now, the Big Island will see the effects first. We will have to see how it interacts with the land, channeling between our islands, gap winds, etc… Keep in mind effects can be felt far from the center of the system. For example, tropical storm force winds extend more than 100 miles from the center and the cloud field is even bigger than that.
Before Darby passes, typical trade wind weather is forecast with clouds and showers for our usual windward and mauka spots, mainly overnight and into the morning. After Darby passes, winds are forecast to turn southeast with hot, humid conditions expected.
Partly cloudy skies with increasing showers for windward areas. High temperatures from 84° to 89°. Winds will be northeasterly from 10 to 25 mph and increasing.
UV index at 12 (“extreme” exposure level)
Winds will be northeasterly possibly from 35 to 55 mph with higher gusts. Mostly cloudy with tropical storm conditions possible, heavy rain at times and possibly damaging winds. Low temperatures from 73° to 78°.
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