Maui Flood ADVISORY to 9 p.m.; Moloka‘i Flood WARNING Extended to 11:15 p.m.
Update: 10:54 p.m. Jan. 18, 2021
The Flood Advisory for the island of Maui is canceled. Weather radar shows that the heavy rain has diminished; therefore, the Flood Advisory is no longer in effect.
A Flash Flood Watch remains in effect through Tuesday afternoon for Oʻahu, Maui, Molokaʻi, Kahoʻolawe and Lānaʻi.
The National Weather Service says “abundant moisture from a stalled front near the Big Island will continue to bring the threat of flash flooding through Tuesday. The greatest areas of risk will be over windward and mountain areas. This moisture will gradually shift westward on Tuesday and will bring increasing chances of heavy rain to Oʻahu. Significant flooding may occur due to the overflow of streams and drainages. Roads in several areas may be closed, along with property damage in urban or low-lying spots due to runoff. Landslides may also occur in areas with steep terrain.”
The National Weather Service in Honolulu has replaced a Flood Warning for the island of Maui with a Flood Advisory until 9 p.m. on Monday, Jan. 18, 2021. The NWS extended a Flood Warning for Molokaʻi until 11:15 p.m., replacing an Advisory that was issued earlier in the day.
At 8:10 p.m., radar indicated moderate to heavy rain over east Molokaʻi, in areas that have already received a significant amount of rainfall earlier today. Although stream levels have fallen slightly over the past couple hours, rainfall intensity is now increasing over these same areas which received the earlier heavy rains. Rainfall rates of around 1 inch per hour are now occurring, and this will likely lead to additional high water levels on area streams along with flash flooding of low lying and poor drainage areas.
At 5:54 p.m., radar indicated locally heavy showers over the west Maui mountains and along the north slope of Haleakalā from near Makawao and Pukalani to near Hāna. Rain was falling at a rate of up to 1 inch per hour. Other moderate to heavy rain may overspread portions of the island later this evening.
At 5:12 p.m., stream gauges on Molokaʻi continued to report high stream levels. Law enforcement reported Kamehameha V highway was closed at Pukoʻo and Kamalo. Although the rain has subsided somewhat, light to moderate rain continues to fall over areas saturated by earlier intense rainfall.
At 2:59 p.m., radar indicated heavy rain anchored over and near the West Maui Mountains. Rain was falling at a rate of 1 to 2 inches per hour, in areas which have already seen significant rainfall today. Flash flooding is occurring or expected to begin shortly.
At 1:43 p.m., radar indicated heavy rain over portions of central and east Maui, mainly near Wailuku, Kahului, Haʻikū, and Keʻanae. In localized areas, rain was falling at a rate of 1 to 2 inches per hour. This heavy rain is falling on already saturated areas, leading to increased runoff.
At 11:50 a.m., radar indicated heavy rain over portions of northern Molokaʻi from south of Kalaupapa to south of Hālawa Valley. Rain was falling at a rate of 1 to 2 inches per hour. Additional heavy rain was developing over far western Molokaʻi near Kepuhi. Conditions appear favorable for additional rain, at times heavy, to develop over Molokaʻi over the next few hours.
A Flash Flood Watch is also in effect for Maui until 6 p.m. on Tuesday, Jan. 19, 2021.
The public is advised to stay away from streams, drainage ditches and low-lying areas prone to flooding.
Rainfall and runoff will also cause hazardous driving conditions due to ponding, reduced visibility and poor braking action.
On Maui, radar at 10:50 a.m. indicated pockets of heavy rain over central and northeast Maui, from near Wailea to Wailuku, and from Kahului to Keʻanae.
The NWS forecast says rain was falling at a rate of 0.5 to 1 inches per hour, but is increasing in intensity. This is in addition to some of the locally heavy rainfall that fell over Maui last night.
Locations in the advisory include but are not limited to: Kahului, Kīhei, Lahaina, Kula, Pukalani, Makawao, Keōkea, Hāliʻimaile, Pāʻia, Puʻunēnē, Haʻikū-Paʻuwela, Wailea, Paʻuwela, Māʻalaea, ʻUlupalakua, Huelo, Mākena, Waikapū, Wailuku and Waiehu.