Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
214 AM EST Sat Jan 11 2020

Valid 00Z Sun Jan 12 2020 - 00Z Sun Jan 19 2020

...Heavy Rainfall Pattern for Hawaii...

Guidance and blended precipitable water imagery support periods of
heavy rainfall over the state this weekend into next week. An
upper trough/low shifts westward over the region underneath a
blocking upper ridge settled to the north of the islands. System
amplitude and slow progression will hold an axis of high
precipitable water values over the islands for multiple days to
offer potential for a prolonged period with a risk of locally
heavy rain. Flash flood watches and/or flood advisories have been
issued statewide and cooled temperatures aloft have prompted
winter weather advisories for Mauna Loa and Mauna Kea.

Meanwhile east-central Pacific high pressure will support brisk
trades during the next few days, with a gradual trend from
easterly to southeasterly in response to surface troughing/low
pressure to the west and northwest of the state. Wind and small
craft advisories along with high surf and offshore gale warnings
have also already been issued for portions of the islands and
maritime interests. Please refer to updated information from WFO
Honolulu for hazards. Weakening of the east-central Pacific high
and a front coming into the picture off to the northwest with
renewed mid-upper level trough development as per most guidance
should allow for trades to slacken into later next week. Frontal
approach may act to also refocus the slow moving channel of lead
moisture into the state into late week.

Schichtel