Extroardinary Rain and Wind in Hawaii: Did El Nino Help?

Although in the tropics, Hawaii rarely gets hit by hurricanes.  

But yesterday, the unusual happened:  hurricane Lala approached, producing stunning precipitation and winds.

The visible satellite imagery yesterday afternoon and evening shows a well-defined eye (indicated by red arrows), with the storm passing westward just south of the Big Island

This morning, we only have an infrared image (since there is no solar radiation!)  This image (indicating cloud temperature) shows the low center to the south of Oahu (red arrow) and a blow-up of convection (thunderstorms) to the northeast of the low center (blue arrow).

Precipitation totals so far have been stunning.  

During this event, some parts of the northeast slopes of Hawaii received over 32 inches.  In contrast, the "Kona" side only got an inch or two.   

All the result of strong, moist northeast winds forced by the storm.  Moist air that was forced to rise by huge volcanoes on the island.

Impressive precipitation contrast on Maui as well, with some locations receiving over 30 inches.

Then there were winds, driven by the huge pressure gradients (change of pressure over distance) associated with the hurricane.

Consider the maximum gusts yesterday over Hawai.   Some locations on the NW side of the island gusted to over 80 mph! Strong winds near the ridge crest as well

Similar gusts were found over the NE side of Maui downstream of the West Maui Mountains.  

I should note that the strong downslope winds on the West Maui Mountains resulted in the destruction of Lahaina from wildfire a few years ago.

Hurricanes are relatively rare in Hawaii, because the water temperatures are generally too cool (you read that right).  During the past 50 years, only one hurricane (Iniki, 1992) has made landfall on a Hawaiian island.

Hurricanes need warm water, generally at least 26.5 C (around 80F), and generally Hawaiian waters are cooler than that.

However, this year there is a strong El Nino, with much warmer water than normal in the tropical Pacific  (see sea surface anomaly map (differences from normal) below)

A close-in view of the sea surface temperatures shows the details.  Need to be in the greeds, yellows, or orange colors.   Just made it!  

Finally, I should note that hundreds of thousands are without power on the islands right now, with the Big Island substantially in the dark.

Not a good time for a Hawaii vacation!