Kona Low eases drought conditions on Big Island, but only in the short term

The Kona Low that drenched parts of Hawai’i toward the end of November helped ease drought conditions, including on the Big Island; however, it was only short-term relief.

According to a Dec. 8 drought information statement from the National Weather Service forecast office in Honolulu, areas of extreme drought were eliminated thanks to the rainfall brought by the storm but most of the island continues to suffer from moderate drought, with severe drought still affecting areas in the interior and along a portion of the northwest coastline.

“More improvements may occur as vegetation regrowth continues in areas with sufficient rainfall,” said the statement. “If follow-up rainfall does not occur, full drought recovery is not likely from just the Kona Low.”

Areas seeing the worst drought impacts are along the leeward slopes of Maunakea and lower slopes of Kaʻū.

The 3-month outlook shows drought will persist on the Big Island as the ongoing El Niño will likely cause below normal precipitation across the state well into 2024. Peak dryness is expected from mid-December through February.

Previous strong El Niño events have resulted in less than 50% of average rainfall during the October through April wet season.

The Kona Low developed late Nov. 28 several hundred miles northwest of Kaua‘i and brought bands of light to moderate rain to the Garden Isle and O‘ahu through Nov. 29, with the most intense rainfall staying east of the Big Island.

The storm shifted west Nov. 30, increasing rainfall over the southeastern half of the island and eastern and southern flanks of Haleakalā on Maui. Heavy rainfall that morning resulted in the closure of Wood Valley Road near Pāhala and Pōhaku Drive in Orchidland Estates near Keaʻau.

Combined rain gauge and radar rainfall estimates showed 11 to 22 inches of rain drenched the eastern portions of the Big Island and Maui from Nov. 30 to Dec. 1.

And it looks like Puna got a good portion of that rainfall.

An automated rain gauge in Pāhoa recorded 12.02 inches of rainfall. Several manual rain gauges in the Community Collaborative Rain, Hail and Snow (CoCoRaHS) network in the Pāhoa area reported amounts from 18.22 inches up to 21.88 inches.

The Pāhoa Beacon automated gauge saw peak rainfall rates of more than 4 inches per hour during the morning of Nov. 30.

A CoCoRaHS rain gauge in the Wainaku area of Hilo also recorded 20.02 inches of rain. Automated gauges in Mountain View, Laupāhoehoe and Kealakomo as well as the Honoli‘i Stream and Pāpaʻikou Well gauges saw between 8.31 inches and 10.21 inches.

Dry weather persisted into the early part of November with a surface ridge of high pressure near the islands keeping winds light through Nov. 3. Trade winds returned the next day. Remnants of a cold front boosted rainfall Nov. 6 and 7 along the windward slopes of Kaua‘i and O‘ahu.

Fresh to strong trade winds produced daily rainfall along windward slopes of the state Nov. 10-17, but resulted in generally dry conditions over leeward areas.

The weather pattern changed Nov. 18, signaling a much wetter period throughout the state for the rest of the month. Prior to the Kona Low, the strongest cold front so far for the 2023-24 wet season reached the state, but did not impact the Big Island, weakening as it passed over O‘ahu on Nov. 20 before dissipating over Maui County later that day.

Even with the Kona Low, most of the rain gauges on the east side of the Big Island saw near to below average rainfall totals for November, which should be one of the wettest months of the year.

Interior and western sections of the island had near to above average rainfall totals. The slopes of the Kohala Mountains seeing below average amounts of rain for the month.

The Pāhoa Beacon rain gauge had the highest monthly total of 20.68 inches, or 129% of average. This site also had the highest daily total among automated gauges, with 12.51 inches logged Nov. 30 during the Kona Low.

The highest overall daily total was 14.32 inches, also Nov. 30, from a manually read CoCoRaHS observer network gauge a few miles southeast of Pāhoa.

There were no November records broken, but the Waikiʻi and Pōhakuloa West rain gauges recorded their highest November totals since 2002 and 2004, respectively.

Rainfall totals for the year through the end of November were near to below average at most Big Island rain gauges. The U.S. Geological Survey gauge at Honoliʻi Stream had the highest year-to-date total of 170.56 inches, or 80% of average.

To see a map of November rainfall totals around the island, click here. You can also find a map of year-to-date rainfall totals here.

The Kona Low also brought freezing temperatures and the first snowfall of the season to the summit of Maunakea.