Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 AM EST Thu Jan 19 2023

Valid 00Z Fri Jan 20 2023 - 00Z Fri Jan 27 2023

The models and ensembles are still fairly agreeable with the
forecast into Tuesday-Wednesday, followed by increasing spread for
an upper trough that develops over and north of the islands with
some potential influence on the precise surface pattern and winds.
 From late this week into the weekend expect the best
moisture/rainfall potential to be over the northwestern islands,
with an initial front nearby on Thursday weakening and a better
defined front reaching its closest proximity around late
Saturday-early Sunday.  During the Thursday-Saturday period,
expect light winds with land/sea breeze influence on showers
(though with some southeasterly focus for the Big Island) early to
transition to stronger southerly flow ahead of the second front. 
Consensus still shows the front weakening/retreating westward
after early Sunday as upper ridging builds overhead and easterly
trades become established.  The next front that approaches should
make greater eastward progress, crossing the islands around
midweek and turning low level winds more northeasterly or
northerly.  Thus far the models are not showing very anomalous
moisture with this last front but there may still be some locally
enhanced rainfall.  Then the terrain focus for showers would shift
with the change in wind direction.  By next Thursday the models
and ensemble members diverge considerably for the amplitude of
upper troughing that reaches the area.  The 00Z ECMWF is a notable
extreme, and change from its prior run, in bringing a fairly deep
upper low down to 30N latitude by late next Thursday (leading into
an even more anomalous southwest drift thereafter).  The resulting
surface reflection in the 00Z ECMWF promotes northerly winds
versus the preferred remaining guidance that shows mostly
northeasterly winds.

Rausch