National Weather Service United States Department of Commerce

A strong low pressure system aloft combined with a low pressure trough at the surface to produce conditions favorable for heavy rainfall and flash flooding over portions of the main Hawaiian Islands. The worst flooding impacts occurred on the islands of Maui and Molokai. Localized flooding impacts also affected north Kauai. Oahu and the Big Island were spared from significant flooding issues.

Heavy rainfall initially affected the windward slopes of Haleakala on January 26. Rainfall spread to all of the slopes on Haleakala on January 27 and persisted through most of the day. Flooding impacts occurred in Makawao and Pulehu in the Upcountry region. Runoff from Upcountry caused flooding in Kihei, which closed South Kihei Road at Kulanihakoi Gulch. Piilani Highway on the southeastern flank of Haleakala was closed near Nuu. In Maui`s central valley, the Maalaea area was inundated by runoff from the nearby fields.

On January 28, rainfall shifted west to the island of Molokai. Flooding closed Kamehameha V Highway (Highway 450) in Kaunakakai, Kawela, and Kamalo. Flood waters also go into several homes in the Kawela area. By the evening of January 28, heavy rainfall eased on Molokai, but resumed over portions of Maui. Shortly after midnight on January 29, flooding once again closed South Kihei Road at Kulanihakoi Gulch. Makawao Avenue in Upcountry Maui was also closed at Maliko Gulch. Heavy rainfall also affected the windward slopes of the Kohala Mountains, and the lower slopes of the Hamakua and North Hilo Districts on the Big Island. While intense at times, this rainfall didn`t persist long enough to cause significant flooding issues.

Rainfall shifted back west on January 29 and mainly affected the slopes of the Koolau Range on Oahu. Fortunately, the rainfall moved quickly and didn`t anchor over specific areas, which helped reduced rainfall totals and flooding impacts.

The island of Kauai finally got its turn at heavy rainfall on January 30. The first episode of rain mainly affected the windward slopes before sunrise. The rainfall was enough to cause Hanalei River to overflow and close Kuhio Highway for a few hours. An intense band of rainfall, lurking offshore to the south all day, finally moved onshore during the late afternoon. Fortunately, it moved fast enough across the island to mitigate flooding in most areas. It was, however, enough to overflow Hanalei River again and close Kuhio Highway for a second time in a day.

The following are notable rainfall totals for the 5-day period ending at 12 AM HST, January 31. All amounts are in inches. These totals are considered preliminary for information purposes only.

Location                             5-day total
Maui County
West Wailuaiki (USGS)                   30.78
Puu Alii                                28.41
Molokai 1                               18.93
Puu Kukui                               15.76
Pukalani                                12.64
Kula Branch Station                      7.26
Kaunakakai Mauka                         7.17
Waikapu Country Club                     6.17

Kilohana (USGS)                         17.82
Mohihi Crossing (USGS)                  13.18
Mount Waialeale (USGS)                   8.74

Moanalua RG (USGS)                      16.05
Nuuanu Upper                             8.41
Makua Range                              8.19

Big Island
Kawainui Stream (USGS)                   5.26
Laupahoehoe                              2.46
Pahoa                                    2.09