Hawaii Island Weather Update for October 25th, 2020

The Flood Advisory issued for the Kona Coast Sunday evening (October 25th) has been canceled, however, unstable weather conditions are expected to linger over Hawaii Island through the new work week.

GFS Rainfall Accumulation Forecast for the next 5 days

Published by: HIRSC - Weather Team

info@hiradioscannercommunity.com


State of Hawai'i Weather Outlook as of Sunday evening (October 25th) from the National Weather Service (NWS).


Synopsis

A surface ridge over the islands will produce locally breezy southeast winds around the Big Island and gentle and variable winds around the smaller islands through tomorrow. Land breezes will bring partial clearing tonight, while sea breezes will produce spotty showers over interior sections tomorrow. A strong low aloft is forecast to form northwest of the area tonight. The atmosphere over the islands will become very moist and unstable. A period of wet weather may start as early as tomorrow night and continue throughout the week.

Discussion

A surface ridge to our northeast is driving southeast flow near the Big Island and Maui. The Big Island and Maui partly block the southeast flow so winds are gentle and variable over the rest of the islands. Southeast flow will continue to push clouds and isolated showers over the Big Island and Maui through tomorrow. Land breezes will clear leeward areas of Maui and the Big Island and the islands from Molokai to Niihau overnight. Clouds and spotty showers will form over interior areas during the afternoon again tomorrow. Models show an upper low forming northwest of the main Hawaiian Islands tonight, then dropping south. This will make the atmosphere increasingly unstable. The atmosphere is already rather moist with PW around 1.5 inches. The atmosphere will become even moister as the upper low pulls tropical air over the islands. The moisture and instability will likely produce a period of wet weather, but we have low confidence in the details. Models have been inconsistent with each other and have been much different from run to run. At this time, the best chance for heavy rain appears to be over Kauai and Oahu, but there could be heavy rain state-wide. Because of the model differences, confidence is low concerning the duration of the heavy rain, which could continue over some areas throughout the week.

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