(BIVN) – The Flood Watch for Maui and Hawaiʻi Counties has been extended, as pockets of heavy rain and isolated thunderstorms continue to be possible along the eastern end of the state.
“A trough continues to lay over the eastern half of the state within a very moist and fairly unstable environment,” the National Weather Service stated on Thursday morning. “Energy moving up from the southwest may initiate return periods of moderate to locally heavy rainfall. This rain has a high probability of focusing on Maui and Hawaii Counties. Locally moderate to heavy showers, with possible isolated thunderstorms, may produce short-lived intense rain rates through the day.”
On Wednesday, lightning in the late afternoon forced the cancellation of some outdoor activities and closed Hawaiʻi County pools in Hilo.
The Flood Watch is expected to be in place through Thursday afternoon.
From the National Weather Service discussion posted just before 4 a.m. Thursday morning:
While it is hard to determine which areas will receive the most rain, little change in the synoptic pattern within this moisy fairly unstable environment ensures that those that receive another inch or more on top of already soaked grounds will experience the greater probability of flooding. The highest low to mid layer moisture will travel east of the state Friday as the broad upper low southwest of the island chain begins to wobble west in response to the passage of a North Central Pacific upper trough this weekend. A cooler and drier air mass behind this trough will descend upon the state early next week. The associated surface front is forecast to reach the islands and back trades around to north northeast late Sunday or early Monday. In the meantime, lingering lower to middle layer moisture over the islands will ensure cloudier skies and periodic trade shower activity, especially over windward locales and upslope mauka, this weekend. The passage of this trough will usher in a much drier air mass where dew points are forecast to fall into the lower 60s by Monday afternoon. A backing near 1030 mb surface high north of the region will tighten the downstream pressure gradient over the islands enough to significantly strengthen early to mid week trade winds. Breezy to locally strong trades at higher elevation will persist, as will much drier conditions, through at least next Thursday.
