Blog: A taste of what you may find on Maui

Rain and Flash Flood Watches in Kihei – what to expect

I woke up to an unusual sound… the sound of rain! In fact, in Kihei it is so unusual that I actually got up to check. A few years ago I had woken up to a similar sound which turned out to be the crackling of a small brush fire nearby (the Maui Fire Department put that out very quickly). But tonight it really is rain. It reminded me of our ‘show-and-tell’ rain gutter on the front of our house. Every time it rains we say, ‘we should really get someone out to extend rain gutters around the other three sides of the house’. Then the rain stops and we forget about it until a few months later when it rains again.

A few nights ago forecasters actually predicted that we’d be getting island-wide rain in the next few days. As usual I ignored the forecast. We live in Kihei. Oahu’s rain forecasts never apply to us. The forecaster went on to say scientists were predicting a ‘wetter than usual rainy season’ for the Hawaiian Islands, and that the ongoing drought conditions on several of the islands would probably be lifted this winter. Except for Maui. He actually said ‘but not on Maui or the Big Island’ (seriously).

Now I’m sure you’re thinking, yikes – our Maui trip will be rained out! Nope, I can almost promise you it won’t, at least not if you’re staying in Kihei, the desert side of the island. Kihei averages about 11 inches of rain a year, though in 2012 it was only 5 inches (compare that to Vancouver BC’s 44 inch rainfall average). Here’s an interesting graph by NOAA plotting Kihei’s rainfall average this year. According to NOAA’s records we’ve had 6 days of rain in Kihei in 2013 (with rainfall averages between 0.1 and 0.5 inches), totaling 2.21 inches of rainfall for 2013 to date.

Accumulated rainfall for KIHEI #2 (HI75)
interesting NOAA graph showing Kihei’s accumulated rainfall for 2013

Yesterday the County of Maui issued an island-wide Flash Flood Watch. Should we be concerned? Depending on where you are… Here is an example of one of these warnings (and since I’m not sure if this link will remain active once the warning has passed, I’ll copy the text here).

The National Weather Service in Honolulu has CONTINUED a FLASH FLOOD WATCH for LANAI, MOLOKAI and MAUI , in effect through late tonight.
A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is very dangerous. Remember that it does not have to be raining heavily where you are for flash flooding to occur. Please monitor the latest forecasts and be prepared to take immediate action if flash flood warnings are issued.

EFFECTS: An upper level trough and surface shear line will approach the state tonight, enhancing an already moist and unstable airmass. The greatest potential for flash flooding will be focused across windward sections but brief heavy showers are possible across the entire watch area.

PRECAUTIONARY MEASURES: AVOID CAMPING OR HIKING NEAR STREAMS AND LOW LYING FLOOD PRONE AREAS. RAINFALL AND RUNOFF WILL ALSO CAUSE HAZARDOUS DRIVING CONDITIONS DUE TO PONDING, REDUCED VISIBILITY AND POOR BRAKING ACTION. DO NOT CROSS FAST FLOWING OR RISING WATER IN YOUR VEHICLE OR ON FOOT. TURN AROUND…DON’T DROWN.

INFORMATION: Maui County Civil Defense will continue to monitor the situation. Please listen to your local radio and TV stations or NOAA Weather Radio broadcasts for any updates. NOAA Weather Radio broadcasts can be reached by calling 1-866-944-5025. NOAA Weather internet service can be found at www.prh.noaa.gov/hnl.

Should you be concerned? Well, as it says in the warning – watch out for water on the roads (your rental car likely doesn’t have great tires for driving in wet conditions). One thing to remember is that rain creates run-off which will make the ocean murky. Don’t go into the ocean when the water is murky (typically for a day or two after the rain)! Why not? Two reasons: 1. who knows what the run-off has washed into the water (debris, dead animals). And 2. sharks come closer to shore when the water is murky to check out the run-off. When the water is murky, they see even less clearly and that is sadly when you’ll hear about shark attacks.