We saw it on Maui a few weeks ago -- flood waters ravaging upcountry roads.
Now, thanks for new radar technology, meteorologists can detect downpours and flash floods better and faster.
"Being able to pinpoint in the storm all the way down to the basin level on where the rain is, is a big plus for Hawaii," said National Weather Service Warning Coordination Meterologist Michael Cantin.
The National Oceanic and Atmospheric Administration just upgraded the four Hawaii radars to dual polarization technology, or "dual pol," as it's commonly called. It allows radars to scan vertically and horizontally. A two-dimensional scan gives forecasters a better look inside a storm.
"Now, because of dual pol, we can get the shape of what we're seeing and it gives us a really good idea if it is heavy rain, whether it's hail or large hail," said Cantin.
In fact, scientists can determine the size of the hail and rain drops before they land on the ground. These upgrades mean faster lead times when it comes to alerting you about the potential for bad weather.
"We're gonna have to see it as it evolves," said Cantin. "Right now we average 40-to-50 minutes lead time for flash floods, so we do really well for the state. So, this could add a few extra minutes."
With the new upgrade, radars can pick up vog -- something the old radars couldn't.
Though the upgraded radars can improve the forecast for most severe weather, like a tornado and hail which hit Windward Oahu last year, meteorologists say water spouts are still difficult to detect because they're usually small and isolated.