Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
336 AM EST Fri Dec 09 2022

Valid 00Z Sat Dec 10 2022 - 00Z Sat Dec 17 2022

Latest model and ensemble solutions still reasonably agree upon
the pattern evolution through at least mid next week which
features surface high pressure settling to the north of the state
supporting moderate to brisk mean island trades into next week in
a pattern with modest moisture for windward terrain/mountain
focusing showers under upper ridging. A closed low meanwhile set
southeast of the state may only nudge the ridge, with pooled
moisture generally holding offshore the Big Island. There is a
growing signal for a digging upper trough and frontal passage over
the islands later next week which should act to disrupt/veer
trades enough to allow a deeper return of moisture into the
region. This looks to fuel at least widespread showers, with some
heavy rainfall potential, across the islands, although there is
still plenty of uncertainty regarding upper low/frontal placement
and QPF amounts. The ECMWF right now shows significantly more QPF
over the islands than the GFS. The ensemble means show no more
than a weak surface low or trough further confirming the lingering
uncertainty. It seems likely a feature will be there, but exact
impacts to Hawaii at this point remain up in the air.
 
Santorelli