WEATHER UPDATE: A final round of moderate to heavy rain will move across the islands on Sunday and Monday before more favorable conditions settle in for the rest of the week
Background
As of 6:00 AM HST on Sunday, April 12:
An upper-level trough approaching the islands from the northwest has restarted the flow of deep tropical moisture over the islands this morning and will likely lead to several bands of moderate to heavy rain showers and a few thunderstorms over the next couple of days. The heaviest rain will likely set up over Oʻahu and Molokaʻi today and will slowly retrograde back toward Kauaʻi on Monday. Later in the week, light trades will develop, but conditions will remain warm and very humid until stronger trades set up midway through the following week.
The National Weather Service has extended the Flash Flood Watch until Monday afternoon, as the ground remains saturated from recent heavy rainfall.
Key points
As of 6:00 AM HST on Sunday, April 12:
On Sunday, the heaviest rainfall will likely impact Oʻahu, Molokaʻi, and Lanaʻi.
On Monday, the heaviest rainfall will shift back toward Kauaʻi.
Maui and Hawaiʻi will largely avoid the worst impacts, but flash flooding is still possible with afternoon showers.
Conditions will slowly improve on Tuesday, with light trades setting back up.
Warm and humid conditions will continue through early next week.
Forecast synopsis
As of 3:49 AM HST on Sunday, April 12:
From the National Weather Service office in Honolulu:
Showers and isolated thunderstorms will spread over the western half of the state becoming heavy over central portions of the state through tonight. The heaviest rain bands are anticipated over Oahu and Molokai, and possibly spread westward over Kauai. Because of the latest rainfall over the last few days, flash flooding is possible. Light and variable winds are expected to prevail through the first half of the week, with light trades returning to the state thereafter.
Weather risk outlook
As of 7:00 AM HST on Sunday, April 12:
NOTE: An updated risk outlook will be posted later this morning.
| County | SUN AM | SUN PM | MON | TUE | WED |
|---|---|---|---|---|---|
| Overall risk: | 2 | 2 | 2 | · | · |
| Kauaʻi | 2 | 2 | 2 | · | · |
| Oʻahu | 2 | 2 | 2 | · | · |
| Maui | 1 | 2 | 1 | · | · |
| Hawaiʻi | 1 | 1 | 1 | · | · |
Key: · - little to none; 1 - minor; 2 - moderate; 3 - major; 4 - extreme
Projected rainfall totals:
As of 6:00 AM HST on Friday, April 10:
Below are projections for the remainder of the rainfall expected between now and midnight on Tuesday from the National Weather Service’s National Digital Forecast Database (NDFD), the ECMWF model, and the GFS model. The NDFD values can be viewed using the NWS’s IDSS Forecast Points tool.
| City | NWS | ECMWF | GFS |
|---|---|---|---|
| Lihue | 2.3 | 2.1 | 1.0 |
| Honolulu | 5.8 | 1.1 | 2.1 |
| Wahiawa | 6.1 | 2.1 | 2.5 |
| Kaneohe | 6.0 | 1.4 | 2.3 |
| Kahului | 0.8 | 0.2 | 0.8 |
| Hana | 1.0 | 0.6 | 0.7 |
| Molokai | 2.8 | 0.8 | 1.1 |
| Lanai | 0.5 | 0.8 | 0.7 |
| Hilo | 0.0 | 0.1 | 0.0 |
| Kona | 0.1 | 0.2 | 0.2 |
More information
For more information on the impacts of this system as it develops, please check out these links:
National Weather Service
- NWS Honolulu homepage
- NWS Honolulu Area Forecast Discussion
- NWS Honolulu on Facebook
- NWS Honolulu on X
Hawaii Emergency Management Agency
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