It's Impact Day on the Big Island of Hawaii from Lala While Gusty Squalls Move into the Caribbean

LALA AND HAWAII

Tropical Storm or Hurricane Lala will make its final approach to the southern tip of the Big Island of Hawaii today. Maximum impacts are likely this afternoon Hawaii time, which is this evening Eastern time.

The biggest threat is from rainfall. Tall mountains enhance tropical rainfall and the track of Lala is going to put the dense moisture feed rotating around the storm square into the huge mountains on Hawaii Island that reach almost 14,000 feet. 2 feet or more of rain is predicted on the mountain slopes, which all has to run downhill, of course. Flash flooding and mudslides are the threat.

It's going to be a close call how much of the Big Island gets the worst of the storm. Lala's center seems to be leaning south so the south slopes seem especially threatened.

This east side or windward side of the Big Island is accustomed to rainfall and occasionally extreme rainfall. In 2018, Hurricane Lane, which was about 150 miles away, caused an incredible 58 inches of rain to fall against those same slopes. That was the second heaviest rain ever measured in the United States from one storm, just behind Hurricane Harvey that flooded metro Houston in 2017.

Wind is going to be an issue at the coast and lower elevations, but mostly in terms of power outages and downed trees. High on the mountains in and through the passes, however, 100+ mph wind gusts are possible. So the higher the elevation, the bigger the wind threat.

The Hawaiian Islands are not prone to surge flooding from storms arriving from the east. But the waves will be massive and will push water over low-lying coastal sections. High tide at Hilo on the northeast side of the Big Island occurs at about 5 PM this afternoon. Some coastal flooding is likely around that time.

If Lala makes it to hurricane strength as forecast, and it crosses the southern tip of Hawaii Island, it will be the first hurricane in the modern record to make landfall on the biggest island in the State of Hawaii. That record goes back to 1949. Although it turns out that there was a hurricane that tracked over the northern part of Hawaii Island and into Maui in 1871. We learned about that relatively recently when Hawaiian-language newspapers of the era were translated.

Tropical storm conditions are likely to spread over Maui and Molokai tonight and into tomorrow, reaching Oahu and Kauai including the Honolulu metropolitan area later on Sunday.

The eastern slopes of the mountains on all of the Hawaiian Islands will be subject to very heavy rainfall. Amounts in the 8- to 12-inch range on Maui and 4 to 6 inches on Oahu and Kauai are forecast.

Everybody in Hawaii should pay close attention to local officials and be sure they're in a safe place to ride out the storm.

ELSEWHERE IN THE PACIFIC

Former Tropical Storm Hernan just to the east of Lala is dying out. It's now a tropical depression and is forecast to dissipate over the ocean.

There are two other areas that the National Hurricane Center is watching. Although development chances in both of those areas are currently in the low range.

IN THE ATLANTIC

We've been watching two disturbances that originally had high odds of organizing into at least a tropical depression, but the odds have come down dramatically. Saharan dust and dry air have taken their toll.

The westernmost disturbance will move into the Caribbean today with gusty winds and some tropical downpours. Any rain is good news in the Caribbean these days, so on balance this should be beneficial.

The easternmost disturbance, which is officially tagged Invest 94L, only has a slight chance of becoming a tropical depression. And those chances are decreasing. The system looks likely to turn north just before reaching the Caribbean. If it doesn't develop soon it will run into a buzz saw of hostile upper winds and no development will be possible. In any case, it doesn't appear to be a significant threat to land.

More systems are moving off of Africa, but there's no evidence of tropical development with any of them yet.